WO2016136172A1 - Method for producing porous polytetrafluoroethylene sheet - Google Patents

Method for producing porous polytetrafluoroethylene sheet Download PDF

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Publication number
WO2016136172A1
WO2016136172A1 PCT/JP2016/000725 JP2016000725W WO2016136172A1 WO 2016136172 A1 WO2016136172 A1 WO 2016136172A1 JP 2016000725 W JP2016000725 W JP 2016000725W WO 2016136172 A1 WO2016136172 A1 WO 2016136172A1
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Prior art keywords
sheet
orifice
extrusion
width
flat die
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PCT/JP2016/000725
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French (fr)
Japanese (ja)
Inventor
山本　勝年
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株式会社サンケイ技研
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Publication of WO2016136172A1 publication Critical patent/WO2016136172A1/en

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    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01D—SEPARATION
    • B01D39/00—Filtering material for liquid or gaseous fluids
    • B01D39/14—Other self-supporting filtering material ; Other filtering material
    • B01D39/16—Other self-supporting filtering material ; Other filtering material of organic material, e.g. synthetic fibres
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/03—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor characterised by the shape of the extruded material at extrusion
    • B29C48/07—Flat, e.g. panels
    • B29C48/08—Flat, e.g. panels flexible, e.g. films
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C48/00—Extrusion moulding, i.e. expressing the moulding material through a die or nozzle which imparts the desired form; Apparatus therefor
    • B29C48/25—Component parts, details or accessories; Auxiliary operations
    • B29C48/30—Extrusion nozzles or dies
    • B29C48/32—Extrusion nozzles or dies with annular openings, e.g. for forming tubular articles
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C55/00—Shaping by stretching, e.g. drawing through a die; Apparatus therefor
    • B29C55/02—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets
    • B29C55/04—Shaping by stretching, e.g. drawing through a die; Apparatus therefor of plates or sheets uniaxial, e.g. oblique
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29C—SHAPING OR JOINING OF PLASTICS; SHAPING OF MATERIAL IN A PLASTIC STATE, NOT OTHERWISE PROVIDED FOR; AFTER-TREATMENT OF THE SHAPED PRODUCTS, e.g. REPAIRING
    • B29C69/00—Combinations of shaping techniques not provided for in a single one of main groups B29C39/00 - B29C67/00, e.g. associations of moulding and joining techniques; Apparatus therefore
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
    • C08J9/00—Working-up of macromolecular substances to porous or cellular articles or materials; After-treatment thereof

Definitions

  • the present invention relates to a method for producing a wide and long and thick polytetrafluoroethylene (hereinafter simply referred to as “PTFE”) porous sheet.
  • PTFE polytetrafluoroethylene
  • the PTFE porous sheet is produced by mixing a PTFE emulsion-polymerized powder, so-called PTFE powder, with a molding aid such as naphtha, rolling through a paste extrusion, and calendering, and then removing the molding aid by heating.
  • the PTFE porous sheet prepared by this manufacturing method is used for filters such as chemical liquid filters and vent filters.
  • the long sheet is stretched in the width direction with a tenter device (the width direction is a direction perpendicular to the extrusion direction). It has been proposed to manufacture by heat-fixing at a temperature equal to or higher than the melting point of PTFE.
  • a PTFE composite synthetic resin sheet prepared by laminating a wide PTFE porous sheet prepared by this manufacturing method and a synthetic resin sheet such as polyester is used for the outer garment such as a windbreaker or a jacket. It is used in the manufacture of rain gear such as shoes, gloves, hats, raincoats and umbrellas.
  • a PTFE composite non-woven fabric prepared by laminating a wide PTFE porous sheet and a non-woven fabric is used for an air filter
  • a PTFE composite glass fiber sheet prepared by laminating a wide PTFE porous sheet and a glass fiber sheet is provided. Used for bug filters.
  • PTFE fine powder was crushed as it was and processed into pulp-like fibers, and a large amount of surfactant was used to disperse the PTFE pulp-like fibers in water, and paper was made.
  • Thick and wide and long PTFE porous sheets could be made by drying and sintering the material, but required a complex and long process.
  • POLYFLON registered trademark of Daikin Industries, Ltd.
  • the manufacturing method of the wide PTFE porous sheet shown by the said literature is a manufacturing method which performs extending
  • a sheet extruded with a paste before stretching is rolled to a thickness of about 200 ⁇ m to create a rolled sheet, and then the sheet is stretched in the extrusion direction using the sheet as a starting material. Without stretching in the direction, a PTFE porous sheet having a width exceeding 100 to 200 times in area magnification could not be obtained.
  • the production method of stretching the long sheet of PTFE in the width direction is limited to the production method of stretching the long sheet of PTFE in the extrusion direction and then stretching in the width direction, and a wide PTFE having a thickness of 200 ⁇ m or less. It was only a porous sheet.
  • a porous sheet can be produced by setting the stretching condition in the width direction of a long sheet to a temperature of 50 ° C. and a stretching speed ratio of 500% / second, and a temperature of 225 ° C. and a stretching speed. At a rate of 5% / second, it is considered that a porous sheet is not formed by breaking, and stretching in the width direction is difficult unless it is under extremely limited stretching conditions.
  • Example 9 in Patent Document 2 shows a method of alternately laminating stretched films that have not been heat-treated after being stretched and heat-treating them at a melting point or higher to obtain a PTFE porous sheet having a thickness of 0.5 mm or more.
  • HYPER-SHEET registered trademark of WL Gore & Associates
  • the said document shows that extending
  • the method of stretching in a state containing the molding aid is a method of performing stretching again after the widthwise stretching after the molding aid removing step, that is, the molding aid drying / extraction step.
  • PTFE does not become porous, and thus undergoes such a troublesome process.
  • Patent Document 4 describes a method for extruding a laminated preform, in which a second crystalline polymer sheet layer is coated with a first crystalline polymer sheet layer.
  • a method of extruding a laminated preform using a molding die is shown, and it is disclosed that the extrusion temperature of the laminated preform is preferably 19 ° C. to 200 ° C. Yes.
  • Patent Document 5 shows a method of using a known paste extrusion device as an extrusion method when forming a laminate, and the shape of the cylinder part of the paste extrusion device used for extrusion when forming a laminate,
  • the cross-section in the direction perpendicular to the axis is a rectangle of 50 mm ⁇ 100 mm, and a shape composed of a nozzle 50 mm ⁇ 5 mm in which one of the cylinder portions is narrowed at the outlet is shown, and the extrusion temperature when forming the laminate is 19 ° C. It is disclosed that it is preferably carried out at ⁇ 200 ° C., and it is disclosed that the extrusion shape when forming the laminate is preferably a rod shape and more preferably a sheet shape.
  • Patent Documents 4 and 5 do not disclose that the sheet is stretched in the width direction after the auxiliary agent is removed from the extruded sheet. However, it is shown that the extruded sheet is rolled to 0.2 mm or less, and the same stretching as in Patent Document 1 is performed after the auxiliary agent is removed.
  • an extrusion apparatus provided with a molding die comprising a preformed body charging part, a throttle part connected to the preformed part charging part, and a fan part having a central angle of 80 ° or more connected to the throttle part Describes the process of extruding the preform into a sheet.
  • the drawing ratio between the cross-sectional area of the preformed body input portion in the extrusion apparatus used in the extrusion process and the minimum cross-sectional area of the drawn portion is the cross-sectional area A1 of the preformed body input portion in the extruder and the minimum cross-sectional area A2 of the drawn portion. And the ratio (A1 / A2).
  • the preform can be extruded with low shear, and a sheet made of a crystalline polymer having flexibility can be obtained.
  • the drawing ratio in the extrusion apparatus used in the extrusion process is preferably 16 or less, and if it exceeds 16, the preform is extruded at high shear, the flexibility of the extrudate cannot be obtained, and stretching at a high magnification is possible. Since it is not possible, a crystalline polymer having a minute pore size may not be produced.
  • the drawing ratio is 8 to 14
  • the preform can be extruded with low shear, and the flexibility of the extrudate can be obtained, so that it can be stretched at a high magnification and has a fine pore size. Crystalline polymers can be made.
  • the preform By setting the center angle of the fan part to 80 ° or more and 160 ° or less, the preform can be extruded with low shear, and a sheet made of a crystalline polymer having flexibility can be obtained. If the center angle is less than 80 °, the distance to the extrusion port is increased to ensure the necessary sample width, and the extrudate is sheared, so the flexibility of the extrudate cannot be obtained and stretching at a high magnification. Therefore, it may not be possible to produce a crystalline polymer having a minute pore size. When the center angle exceeds 160 °, uniform extrusion in the width direction may be difficult.
  • the center angle is 90 ° or more and 140 ° or less, the distance from the uppermost part of the fan part to the outlet width of the fan part becomes appropriate, so the preform can be extruded with low shear, and the extrudate Therefore, it is possible to stretch at a high magnification, and it is possible to produce a crystalline polymer having a minute pore size.
  • the exit width of the fan part in the extrusion device used in the extrusion process is the extrusion width of the preform in the extrusion device.
  • the outlet width of the fan section By setting the outlet width of the fan section to 150 mm to 500 mm, the preform can be extruded with low shear, and a sheet made of a crystalline polymer having flexibility can be obtained. If the exit width of the fan part is less than 150 mm, stable stretching may not be possible. If the outlet width of the fan part exceeds 500 mm, the distance from the uppermost part of the fan part to the outlet width of the fan part becomes longer, so that the preform is extruded at high shear, and the flexibility of the extrudate is obtained.
  • the outlet width of the fan part is 200 mm to 400 mm
  • the distance from the uppermost part of the fan part to the outlet width of the fan part is appropriate, so that the preform can be extruded with low shear. Since the flexibility of the product can be obtained, it is possible to stretch at a high magnification, and it is possible to produce a crystalline polymer having a minute pore size.
  • a method of extruding the preform at a temperature of 19 ° C. to 200 ° C. with an extruder is preferable.
  • the thickness of the sheet made of the crystalline polymer obtained by the extrusion process is preferably 50 ⁇ m to 250 ⁇ m. If it is less than 50 ⁇ m, it may break during film formation. If it exceeds 250 ⁇ m, too much load is applied to the rolling mill. Sometimes. It is described that a thickness of 80 ⁇ m to 200 ⁇ m is advantageous in terms of suitability for multi-stage rolling.
  • Patent Document 6 discloses a molding including a preformed body charging portion, a throttle portion connected to the preformed body charging portion, and a fan portion connected to the throttle portion and having a central angle of 80 ° or more.
  • a mold is disclosed, the drawing ratio of the cross-sectional area of the preformed body input portion in the molding die to the minimum cross-sectional area of the drawn portion is 16 or less, the exit width of the fan portion is 150 mm to 500 mm, It is disclosed that the temperature for extruding the preform is 19 ° C. to 200 ° C., and the thickness of the sheet made of the crystalline polymer obtained by the extrusion process is 50 ⁇ m to 250 ⁇ m.
  • extrusion can be performed while applying high shear to all of the feeding direction, thickness direction, and width direction of the preform without excessive press pressure. Since a sheet made of a crystalline polymer can be obtained, a crystalline polymer microporous film having an average thickness of 50 ⁇ m or less can be produced only by extrusion and rolling with a calender roll, which had been impossible in the past.
  • the outlet width of the fan portion refers to the outlet opening length or width of the fan portion, and refers to a width in which the width direction of the downstream outlet in the fan portion is a constant value.
  • the center angle of the fan part is 30 ° or more and 75 ° or less and the outlet width is 200 mm or more and 600 mm or less, it is possible to apply a higher shearing force in the width direction to the preform in addition to the shearing effect of the drawing ratio. become.
  • the thickness of the sheet-like molded body obtained by extrusion can be defined by the average thickness at the lower part of the outlet of the extrusion apparatus. By appropriately setting the thickness of the sheet-like molded body, the extrusion process and the rolling process can be performed more smoothly. Can be done.
  • the average thickness of the downstream outlet in the fan is preferably 0.5 mm or more and 3.0 mm or less, and the preform can be extruded with high shear and smoothness.
  • the extrusion speed of the preform in the extruder is preferably 0.5 m / min to 10.0 m / min, and the preform can be extruded with high shear and smoothness.
  • the extrusion temperature in the extrusion step is preferably 30 ° C. or more and 60 ° C. or less from the viewpoint of shape stability, and the preform can be extruded with high shear and smoothness.
  • a sheet made of a crystalline polymer obtained by an extrusion process is a sheet made of a tough crystalline polymer with high shear applied to all directions of the feeding direction, the width direction, and the thickness direction, and the toughness is defined. It can be expressed by the strength at the tensile magnification. A tensile strength of 6 MPa or more is preferable in order to obtain a tensile ratio of 1,000% in the width direction of the sheet made of the crystalline polymer obtained by the extrusion process.
  • a preformed body charging part for charging a preformed body a throttle part connected to the downstream side of the preformed body charging part, connected to a downstream side of the throttle part, and
  • a molding die having a fan part having a central angle of 30 ° or more and less than 80 ° and an exit width of 200 mm or more, and a maximum cross-sectional area in the direction orthogonal to the extrusion direction in the preformed body charging part
  • the drawing ratio of the extrusion direction and the minimum cross-sectional area in the orthogonal direction in the drawing part is 50 or more
  • the outlet width of the fan part is 200 mm or more
  • the average thickness of the fan part outlet is 0.5 mm or more and 3.0 mm or less
  • Extrusion speed of 0.5 m / min to 10.0 m / min
  • extrusion temperature in extrusion process of 30 ° C.
  • a crystalline polymer microporous film having an average thickness of 50 ⁇ m or less can be produced only by extrusion and rolling by a calender roll.
  • JP 2007-260547 A Japanese Patent Laid-Open No. 51-30277 JP 2009-24040 A JP 2012-192308 A JP 2012-139624 A JP 2012-172805 A JP 2012-206113 A
  • Patent Document 6 is intended to produce a crystalline polymer sheet having a thickness of 50 ⁇ m to 250 ⁇ m using a molding die having a drawing ratio of 16 or less by an extrusion process. It is an invention that is not considered to produce a wide and long PTFE porous sheet having a thickness of 0.5 mm or more.
  • the extrusion-molded sheet described in Patent Document 7 has a drawing ratio of 50 or more, and a molding die having an average thickness of the fan part outlet of 0.5 mm or more and 3.0 mm or less is used.
  • a drawing ratio 50 or more, it cannot actually be stretched in the width direction before stretching in the extrusion direction.
  • Patent Document 7 The invention described in Patent Document 7 is intended to produce a sheet having a thickness of 50 ⁇ m through an extrusion process and a rolling process, and has a thickness of 0.5 mm or more, a wide and long PTFE. Producing a porous sheet is an invention that has not been considered.
  • the present inventor has a problem that the first direction in which a PTFE paste extrudate is stretched is limited to the extruding direction in the prior art, and an extruded sheet having a width of 0.5 mm or more and 3.0 mm or less shown in Patent Document 7 is wide. The problem of being unable to stretch in the direction was studied.
  • polymerized particles of PTFE fine powder have an elliptical spherical shape like rice grains of 0.2 ⁇ m to 0.4 ⁇ m, as shown in FIG.
  • the polymer particles are molded while being pressurized from the surroundings. Therefore, the molded product formed by the extrusion direction is such that the major axis direction of the elliptical spherical shape of the polymer particles is aligned. And found to align in the rolling direction.
  • the polymer particles are strongly aligned in the extrusion direction of the molded product, and when the molded product is pulled in the width direction after removal of the auxiliary agent, as shown in FIG. Thus, it was found that the film could not be stretched in the width direction and could only be stretched in the extrusion direction or the rolling direction.
  • the polymer particles having the aligned direction are not simply aligned, but the physical bond strength of the polymer particles is increased.
  • the part is deformed into fibrils of ultrafine fibers straddling between the polymer particles, and a part thereof is changed into a node that connects the fibrils.
  • a porous article composed of fibrils and nodes can be obtained.
  • POLYFLON paper is manufactured by a method of making PTFE fiberized short fibers, and a sheet with a thickness of 0.5 mm and a porosity of 78% and a sheet with a thickness of 1 mm and a porosity of 76% are commercially available. It is inferior in strength and drape because it is only entangled.
  • HYPER-SHEET is a porous sheet obtained by laminating and sintering stretched PTFE films so that their stretch directions are alternated. Since this porous sheet has a specific gravity of 0.6 g / cc and a specific gravity of PTFE of 2.1 g / cc to 2.2 g / cc, the porosity is 71% to 73%.
  • the thickness of the sheet is 0.5 mm to 10 mm. However, since this sheet is manufactured by alternately stacking thin films of 10 ⁇ m to 20 ⁇ m, the width and length of the manufactured sheet can be up to 1.5 m ⁇ 3 m according to the product catalog of the manufacturer. It is limited and inferior to drape.
  • the present inventor has changed the width of the polymer particles aligned in the extrusion direction in paste extrusion molding in the width direction, thereby aligning the paste extrusion molded sheet in the width direction without stretching the extrusion direction.
  • the inventors have found a wide and long, thick and thick PTFE porous sheet having a good draping property.
  • a preform is prepared from PTFE powder to which a molding aid is added, and the preform is put into a paste extrusion mold, By continuously extruding the preform in the molding die by a ram for extruding the preform, a long extrusion sheet is formed in the extrusion direction, and the molding aid is removed from the extrusion sheet.
  • a molding aid removal sheet fix both ends of the molding aid removal sheet in the tenter device in the width direction, and place the molding aid removal sheet in the width direction only in the environment above the room temperature transition temperature of PTFE.
  • a width direction stretched sheet is prepared by stretching 1.2 times to 25 times the width, and the width direction stretched sheet is heat-set at a temperature near the melting point of PTFE.
  • An FE porous sheet, and the molding die includes a continuous cylinder, an orifice and a flat die, the cylinder has a hollow cylindrical shape, and the orifice connected to the cylinder has a hollow rectangular shape.
  • the ratio of the cross-sectional area of the orifice hollow part to the cross-sectional area of the cylinder hollow part is a reduction ratio of 10: 1 to 30: 1, and the rectangular cross-section of the orifice hollow part has a short long side.
  • the flat die that is a rectangle that is 1 to 3 times the length of the side and that is connected to the orifice that is the outlet of the orifice has two flat surfaces that spread in a fan shape with the orifice side of the orifice as the base, It is surrounded by side surfaces that connect both side ends of the two planes, forms a hollow fan shape with a narrow flat die opening formed at the tip of the fan-shaped arc side, and extends from the fan-shaped base of the two planes to a circle.
  • the distance between the two flat surfaces is narrowed toward the side tip, and the opening area of the flat die opening is 125% to 300% of the opening area of the orifice of the orifice.
  • the internal length between both side surfaces in the die opening is 100 mm to 500 mm, and the internal length between the two planes is 1 mm to 5 mm.
  • the method for producing a porous PTFE sheet according to the present invention comprises preparing a preform from PTFE powder to which a molding aid has been added, putting the preform into a paste extrusion mold, and forming the mold.
  • a long extrusion sheet is formed in the extrusion direction, and the extrusion sheet is rolled by a rolling roll, A rolled sheet having a thickness of 0.5 mm or more and a thickness of 35% or more of the original thickness is prepared, and a forming aid is removed from the rolled sheet to form a forming aid-removed rolled sheet, and the forming is performed on the tenter device.
  • a cylinder, an orifice, and a flat die and the cylinder has a hollow cylindrical shape.
  • the orifice connected to the cylinder has a hollow rectangular shape, and the orifice hollow with respect to the cross-sectional area of the hollow portion of the cylinder.
  • the ratio of the cross-sectional area of the portion is a drawing ratio of 10: 1 to 30: 1
  • the rectangular cross section of the orifice hollow portion is a rectangle whose long side is 1 to 3 times the length of the short side
  • the flat die connected to the orifice that is the outlet of the orifice has two planes that expand in a fan shape with the orifice side of the orifice as a base, and both sides of the two planes. Are formed in a hollow fan shape in which a narrow flat die opening is formed at the fan-shaped arc side tip, and the two flat fan-shaped bases toward the arc-side tip.
  • the flat die opening is configured such that the opening area of the flat die opening is 125% to 300% of the opening area of the orifice of the orifice, and between the two side surfaces of the flat die opening.
  • the inner length is 100 mm to 500 mm, and the inner length between the two planes is 1 mm to 5 mm.
  • a long PTFE porous sheet having a width of 5 m exceeding 2.5 m and a thickness of 0.5 mm or more can be easily produced.
  • 2 is an electron micrograph of PTFE polymer particles. It is a photograph which shows the state which pulled and cracked the extruded product whose cross-sectional area ratio of a cylinder and an orifice is 100 to 1 (RR100). It is a photograph which shows the orientation state of the superposition
  • FIG. 4 is a conceptual diagram of aligned orientation in which PTFE polymer particles in a flat die are macroscopically related to the photograph of FIG. 3.
  • the PTFE fine powder according to an embodiment of the present invention is preferably a homopolymer product having a number average molecular weight of 4 million or more.
  • the inner surface of the cylinder in the molding die according to the embodiment of the present invention is not particularly limited as long as it is hollow, and may be circular in cross section or rectangular in cross section.
  • the cross section of the orifice hollow part is rectangular, whether the longer side of the rectangular side of the cross section of the orifice hollow part is in a direction perpendicular to the flat die or in a parallel direction. Either of these may be used.
  • the drawing ratio of the cross-sectional area of the orifice hollow part to the cross-sectional area of the cylinder hollow part is 10: 1 to 30: 1.
  • the opening area of the flat die opening is the product of the internal length between both side surfaces of the flat die opening and the internal length between the two planes.
  • the means for producing the extrusion sheet according to the embodiment of the present invention is in the structure of a paste extrusion mold including a cylinder, an orifice, and a flat die arranged in series, Correlation of orifice and flat die.
  • the role of the three parts of the mold is where the cylinder inserts the preform, and as shown in FIG. 8, the direction in which the polymer particles in the cylinder are arranged is completely random, and from the entrance direction of the preform.
  • the ram undergoes an extruding action, and then the PTFE polymer particles undergo an action of aligning in the extruding direction at the orifice.
  • the process proceeds to a flat die that spreads in a fan shape, where the opening area of the flat die opening is made larger than the opening area of the orifice of the orifice at the point of proceeding to this flat die, and the orifice drawing ratio is 30 or less.
  • the alignment of the polymer particles aligned in the extrusion direction is broken at the orifice of the orifice and changed in the width direction, it can be stretched in the width direction.
  • the schematic diagram shown in the upper right represents the part (S1) in the left diagram
  • the schematic diagram represented in the middle right represents the part (S2) in the left diagram and represented in the lower right.
  • the schematic diagram represents a portion (S3) in the left diagram. The state changing in this way is shown in FIGS.
  • the area of the flat die opening is 125% to 300% of the opening area of the orifice of the orifice. Conversely, if the opening area of the flat die opening is smaller than the opening area of the orifice of the orifice, the polymer particles are further aligned in the extrusion direction inside the flat die, and the alignment direction of the polymer particles remains in the extrusion direction. It becomes impossible to stretch in the width direction.
  • the gap between the flat die openings that is, the inner length between two planes in the flat die openings is less than 1 mm
  • the polymer particles are aligned in the extrusion direction due to the resistance between the walls in the flat die openings. Therefore, stretching in the width direction cannot be performed.
  • the thickness of the PTFE porous sheet according to the embodiment of the present invention is determined by setting an internal length between two planes in the flat die opening, and is a minimum of 1 mm to a maximum of 5 mm.
  • the minimum thickness rolled by the rolling roll according to the embodiment of the present invention is limited to a sheet rolled up to 35% of the thickness of the extruded sheet extruded by the paste extrusion mold.
  • the extruded sheet can be rolled to about 0.5 mm.
  • the auxiliary agent-containing sheet extruded by the present invention is rolled to 35% of the original thickness with a rolling roll, the auxiliary agent removal sheet after removal of the auxiliary agent can be stretched in the width direction. Become. If it is rolled to a thickness of less than 35% of the original thickness, it cannot be stretched in the width direction.
  • the tenter device used for stretching in the width direction is preferably a pin tenter that employs pins that insert and hold both ends of the sheet in that the thickness of the sheet can be freely changed.
  • the upper limit of the width of the sheet is a problem of the tenter device, but a tenter device having a width exceeding 5 m is used.
  • the PTFE porous sheet a biaxially stretched sheet having a width of 2500 mm that is stretched about 200 mm to about 10 times is manufactured. Therefore, a PTFE porous chamber having a width of 10 m and a width of 5 m is formed from a molded extruded sheet having a width of 500 mm. It is possible to create a quality sheet.
  • the room temperature transition temperature of PTFE described as the stretching temperature at the time of stretching in the width direction is the transition temperature at which the absorption peak temperature measured with a differential scanning calorimeter is between 19 ° C. and 21 ° C. of room temperature. means.
  • the actual stretching temperature should be controlled and is 50 ° C. or higher, preferably 100 ° C. or higher. Thus, a long sheet having a large thickness and a wide width is obtained by stretching the extruded sheet in the width direction.
  • the extruded sheet or rolled sheet according to the embodiment of the present invention is stretched in the width direction and then stretched 1.2 times or more in the sheet extruding direction without being heat-set.
  • the biaxially stretched sheet can be heat-set to obtain a PTFE porous sheet.
  • the draw ratio in the extrusion direction is a maximum of 25 times.
  • the heat setting treatment is usually performed at a melting point of PTFE or higher, but is not limited thereto, and may be heat-treated at a temperature lower than the melting point and 50 ° C. higher than the stretching temperature.
  • the PTFE porous sheet having the draping property in the case of a PTFE porous sheet having a thickness of 1 mm and a porosity of 70% to 75%, the length of the sheet from the horizontal state until the drooping starts is determined. 4 cm or less is achieved. As the thickness exceeds 1% and the porosity exceeds 75%, the sheet is more likely to sag, and the length of the sheet until it starts to sag from the horizontal state becomes shorter than 4 cm, thus improving the drape.
  • the drapeability is improved because the length of the sheet until it starts to sag from the horizontal state becomes shorter than 4 cm.
  • the porosity 95%
  • the length of the sheet until it starts to hang down from the horizontal state within a certain range of thickness of 1 mm or more is 4 cm or less.
  • the thickness is 0.5 mm
  • the length of the sheet until it starts to hang down from the horizontal state in a certain range where the porosity is less than 75% is 4 cm or less.
  • a thick, wide, and long PTFE porous sheet can be provided by the method for producing a porous PTFE sheet according to an embodiment of the present invention.
  • Mold The PTFE porous sheet in this example is achieved by a mold having the following shape in its production.
  • the paste extrusion mold 10 includes a cylinder 11, an orifice 12, and a fan-shaped flat die 13 filled with a preform.
  • the cylinder 11 has a cross-sectional inner surface shape of a square with a side a of 70 mm in length.
  • the orifice 12 connected to the lower portion of the cylinder 11 has a throttle angle of 70 degrees, and the throttle opening has a width d of 15 mm in the direction in which the flat die 13 extends in a fan shape.
  • the width c in the direction is 20 mm, the aperture ratio is 16.33, and the length L is 20 mm.
  • a flat die 13 extending in a fan shape with an angle of 80 degrees is connected to the tip of the orifice of the orifice.
  • the flat die 13 has a hollow sector shape surrounded by a pair of flat plates extending in a fan shape and side plates connecting both side ends of the pair of flat plates.
  • the distance between the pair of flat plates gradually decreases from the hollow fan-shaped base to the flat die opening at the tip of the fan-shaped arc side, and the flat die opening width B is 250 mm.
  • the gap T at the tip of the flat die opening, which gradually narrows as it expands in a fan shape, is 2.2 mm
  • the opening area of the flat die opening has a fan-shaped shape that increases by 183% from the opening area of the orifice orifice.
  • paste extrusion mold is not limited to the above-mentioned size, and may be appropriately changed according to the size of the porous sheet as the final object.
  • Sheet Molding PTFE fine powder weighs 1 kg of F106 (Daikin Industries, Ltd.) into a wide-mouthed polyethylene bottle, and then adds 23 parts by weight of molding aid ISOPAR (registered trademark of Exxon Mobile Corporation) for 1 day and night. Aged by incubation at 25 ° C.
  • the pre-formed body was prepared by compressing a 1 kg portion of the above-mentioned heat-aging powder with a hollow prismatic compression-shaped body having a square cross section of 69 mm and a length of 175 mm.
  • the preform is inserted into the above paste extrusion mold 10 to produce a continuous extrusion sheet at a ram speed of about 15 mm / min, and the molding aid contained in the extrusion sheet is removed by heating in a drying furnace.
  • a molding aid removing sheet was prepared.
  • the obtained sheet for forming auxiliary agent removal is a sheet having a width of 210 mm shrunk by the tension at the time of winding, and a thickness 2.8 mm increased by expanding from the gap 2.2 mm at the tip of the flat die opening of the paste extrusion mold. Met.
  • the preform is prepared in accordance with the shape and size of the paste extrusion mold. However, if the shape and size of the paste extrusion mold changes, the preform is molded accordingly. Body shape and size also change.
  • one end of the molding aid removing sheet in the width direction is provided at the left end of the stretch test instrument (a tenter device such as a pin tenter is used in manufacturing).
  • the fixed side clip was fixed by nut tightening, and the other end in the width direction of the molding aid removing sheet was fixed to the movable side clip located to the right of the fixed side clip by nut tightening.
  • the distance between the fixed side clip and the movable side clip is 5 cm.
  • the handwheel handle at the right end of the extension test instrument is turned to slide the movable side clip to the right, and the interval between the fixed side clip and the movable side clip is expanded to 30 cm, as shown in FIG.
  • a 5 cm long forming auxiliary agent removing sheet was prepared by stretching the width direction stretched sheet 6 times to a 30 cm length.
  • This stretching test instrument was manually performed and stretched 6 times while heating using a hot air generator Plajet (trademark of ISHIZAKI ELECTRIC MFG. CO., Ltd.).
  • the temperature of PTFE at the time of stretching was measured with a laser thermometer AD-5611A (A & D Company, Limited). The temperature range was 100 ° C to 150 ° C.
  • the widthwise stretched sheet was sandwiched between clips, and heat setting was performed for 30 minutes in a heating furnace at 370 ° C. to prepare a thick porous sheet according to Example 1.
  • the extruded sheet was dried and then uniformly stretched in the width direction of the sheet to obtain a thick PTFE porous sheet having a porosity of 78%.
  • This PTFE porous sheet is a continuous wide and thick sheet without being subjected to the rolling action of a rolling roll.
  • the sheet can be uniformly stretched in the width direction.
  • the PTFE paste flows in the extrusion direction by an orifice having a drawing ratio of 16.33 in this paste extrusion mold, but the paste is fan-shaped in the flat die ahead of it. This is because the flow of the paste changes from the extrusion direction to the width direction in the process of spreading to the width direction, so that the particle orientation of PTFE changes in the width direction orthogonal to the extrusion direction.
  • Example 1 After processing the extruded sheet before drying and removing the molding aid formed in the same manner as in Example 1 into a continuous rolled sheet having a thickness of 1.5 mm (68% of the original thickness) with a rolling roll in the same direction as the extrusion direction. The molding aid was removed as in Example 1.
  • Example 1 As a sample for a comparative test as in Example 1, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction from the rolled sheet of this auxiliary forming agent, and stretched in the width direction as in Example 1. Then, a stretched sheet in the width direction was prepared, and heat setting was performed to obtain a thick porous sheet having a porosity of 79%.
  • Example 1 After processing the extrusion-molded sheet before drying and removing the molding aid formed in the same manner as in Example 1 into a continuous rolled sheet having a thickness of 1.2 mm (55% of the original thickness) with a rolling roll in the same direction as the extrusion direction. The molding aid was removed as in Example 1.
  • Example 1 As a sample for a comparative test as in Example 1, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction from the rolled sheet of this auxiliary forming agent, and stretched in the width direction as in Example 1. Then, a width direction stretched sheet was prepared, and heat setting was performed to obtain a thick porous sheet having a porosity of 75%.
  • This example is a paste extrusion mold using a die that is slightly smaller than the paste extrusion mold used in Example 1, that is, the cylinder is a square with an inner surface shape of a cross section of a side a of 50 mm in length.
  • the orifice continuously provided at the lower portion of the cylinder has a throttle angle of 60 degrees, the throttle opening has a width d of 10 mm in a fan-shaped direction, and a width c of 20 mm in the direction of the first throttle.
  • the aperture ratio is 12.50, the length L is 20 mm, and a flat die extending in a fan shape with an angle of 70 degrees is connected to the tip of the orifice aperture. .
  • the flat die has a hollow sector shape surrounded by a pair of flat plates extending in a fan shape and side plates connecting both side ends of the pair of flat plates.
  • the distance between the pair of flat plates gradually decreases from the hollow fan-shaped base to the flat die opening at the tip of the fan-shaped arc side, and the flat die opening width B is 150 mm.
  • the gap T at the tip of the flat die opening that gradually narrows as it expands in a fan shape is 2 mm
  • the opening area of the flat die opening has a shape that expands in a fan shape that is 150% larger than the opening area of the orifice aperture.
  • Example 1 Using the paste extrusion molds of different sizes, an extrusion sheet was prepared in the same procedure as in Example 1, and the extrusion sheet was thickened with a rolling roll in the same direction as the extrusion direction before drying and removing the molding aid. After processing into a 1 mm (50% of the original thickness) continuous rolled sheet, the molding aid was removed as in Example 1.
  • Example 1 As a sample for a comparative test as in Example 1, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction from the rolled sheet of this auxiliary forming agent, and stretched in the width direction as in Example 1. Thus, a width direction stretched sheet was prepared, and heat setting was further performed to obtain a thick PTFE porous sheet having a porosity of 73%.
  • the forming aid removing sheet before being processed into a rolled sheet had a width of 146 mm and a thickness of 2.4 mm.
  • Example 4 each extruded sheet was rolled to the above thickness by a calender roll. Thereafter, the molding aid was removed in the same manner as in Example 1, and the molding aid-removed rolling sheet from which the molding aid had been removed by drying was stretched in the width direction, and then stretched in the extrusion direction. A long and wide PTFE porous sheet was obtained.
  • the extrusion molded sheet before drying removal of the molding aid formed in the same manner as in Example 1 was processed into a continuous rolled sheet having a thickness of 0.5 mm with a rolling roll in the same direction as the extrusion direction, and then molded in the same manner as in Example 1.
  • the auxiliary was removed.
  • Example 1 As a sample for a comparative test as in Example 1, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction from the rolled sheet of this auxiliary forming agent, and stretched in the width direction as in Example 1. However, necking occurred due to the part that did not stretch and the part that was locally stretched, and uniform stretching was not possible.
  • Example 4 Continuously having a thickness of 0.13 mm (6.5% of the original thickness) with a rolling roll in the same direction as the extrusion direction of the extruded sheet before drying removal of the molding aid molded with the same paste extrusion mold as in Example 4. After processing into the rolled sheet, the molding aid was removed in the same manner as in Example 1. In the same manner as in Example 1, the forming aid was removed from the forming aid-removed rolled sheet.
  • the above forming auxiliary agent removing sheet is cut by a length of 50 mm in the extrusion direction, and both ends thereof are held and stretched in the width direction.
  • the stretching action was applied only to the local area, necking occurred, and uniform stretching could not be achieved.
  • the draping property of the PTFE porous sheet having a thickness of about 1 mm and a porosity of about 75% and the POLYFLON paper having a thickness of about 1 mm and a porosity of about 76%, as prepared in Example 3, was obtained.
  • the PTFE porous sheet of Example 3 is shown on the near side of the photograph of FIG. 12, and the POLYFLON paper is reflected on the back of the photograph of FIG.
  • the drapeability of the PTFE porous sheet prepared in Example 3 is higher than that of POLYFLON paper.
  • the PTFE porous sheet prepared in Example 3 started to sag 3 cm, whereas the POLYFLON paper started to sag 10 cm.
  • the PTFE porous sheet of Example 3 is shown in the front side of the photograph in FIG. 13, and HYPER-SHEET is in the back of the photograph.
  • the drapeability of the PTFE porous sheet prepared in Example 3 is higher than that of HYPER-SHEEET.
  • the PTFE porous sheet prepared in Example 3 started to sag 3 cm, whereas HYPER-SHEET started to sag 15 cm.
  • the PTFE porous sheet produced by the production method of the present invention can be used as an inner material that comes into contact with the skin when it is fixed with a cast bandage, for example, in the case of a fracture. Moreover, it can be used for the point where the shape changes in a complicated manner, such as a pipe for flowing a liquid of phosphoric acid used in a semiconductor manufacturing process, a joint or a heat insulating heat insulating material around a valve. Furthermore, it can be used as a packaging material for articles. In addition, it can be used in a wide range such as cushioning materials, electronic device sealing materials, liquid crystal substrate installation members, and insulating materials.

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Abstract

The purpose of the present invention is to provide a method for producing a porous PTFE sheet having a large thickness and a large width by drawing a long paste extruded sheet only in the width direction. The method for producing a porous PTFE sheet according to the present invention comprises: producing an extrusion-molded sheet with a paste extrusion molding mold (10); drawing a molding aid-removed sheet, which is produced by removing a molding aid from the extrusion-molded sheet, in the width direction at a draw ratio of 1.2 to 25 times with a tenter device to produce a width-direction-drawn sheet; and then subjecting the width-direction-drawn sheet to a thermal fixing treatment, thereby producing the porous PTFE sheet. In the method, the paste extrusion molding mold (10) is composed of a cylinder (11), an orifice (12) and a fan-shaped flat die (13). In the paste extrusion molding mold (10), the drawing ratio of the cross-sectional area of a hollow part of the orifice to the cross-sectional area of a hollow part of the cylinder is 10:1 to 30:1, the opening area (B×T) of an opening of the flat die is 125 to 300% of the opening area (c×d) of a nozzle of the orifice, the internal length between both side surfaces of the opening of the flat die is 100 to 500 mm, and the internal length between two flat surfaces is 1 to 5 mm.

Description

ポリテトラフルオロエチレン多孔質シートの製造方法Method for producing polytetrafluoroethylene porous sheet
　本発明は、広幅及び長尺で、かつ、肉厚のポリテトラフルオロエチレン（以下、単に「ＰＴＦＥ」という。）多孔質シートを製造する方法に関する。 The present invention relates to a method for producing a wide and long and thick polytetrafluoroethylene (hereinafter simply referred to as “PTFE”) porous sheet.
　ＰＴＦＥ多孔質シートの製法としては、ＰＴＦＥを乳化重合した粉末、いわゆるＰＴＦＥのパウダーにナフサ等の成形助剤を混和し、ペースト押出成形を経て、カレンダーロールで圧延した後に、成形助剤を加熱除去したＰＴＦＥの長尺シートを作成し、当該長尺シートを押出方向にのみ延伸した後、ＰＴＦＥの融点以上の温度で熱固定処理して製造するＰＴＦＥ多孔質シートが提案されている。 The PTFE porous sheet is produced by mixing a PTFE emulsion-polymerized powder, so-called PTFE powder, with a molding aid such as naphtha, rolling through a paste extrusion, and calendering, and then removing the molding aid by heating. There has been proposed a PTFE porous sheet produced by producing a long sheet of PTFE, stretching the long sheet only in the extrusion direction, and then heat-setting at a temperature equal to or higher than the melting point of PTFE.
　この製法により作成されたＰＴＦＥ多孔質シートは、薬液フィルターやベントフィルターなどのフィルターに使用されている。 The PTFE porous sheet prepared by this manufacturing method is used for filters such as chemical liquid filters and vent filters.
　一方、広幅のＰＴＦＥ多孔質シートの製法としては、ＰＴＦＥの長尺シートを押出方向に延伸した後、当該長尺シートをテンター装置で幅方向（幅方向とは、押出方向に直交する方向である）に延伸し、ＰＴＦＥの融点以上の温度で熱固定処理して製造することが提案されている。 On the other hand, as a method for producing a wide PTFE porous sheet, after a long sheet of PTFE is stretched in the extrusion direction, the long sheet is stretched in the width direction with a tenter device (the width direction is a direction perpendicular to the extrusion direction). It has been proposed to manufacture by heat-fixing at a temperature equal to or higher than the melting point of PTFE.
　この製法により作成された広幅のＰＴＦＥ多孔質シートとポリエステルなどの合成樹脂製シートとを貼り合わせて作成したＰＴＦＥ複合合成樹脂製シートが、その防水性を利用して、ウインドブレーカーやヤッケなどの外衣、靴、手袋、帽子、レインコートや傘などの雨具の製造に使用されている。 A PTFE composite synthetic resin sheet prepared by laminating a wide PTFE porous sheet prepared by this manufacturing method and a synthetic resin sheet such as polyester is used for the outer garment such as a windbreaker or a jacket. It is used in the manufacture of rain gear such as shoes, gloves, hats, raincoats and umbrellas.
　また、広幅のＰＴＦＥ多孔質シートと不織布とを貼り合わせて作成したＰＴＦＥ複合不織布がエアーフィルターに使用され、広幅のＰＴＦＥ多孔質シートとガラス繊維シートとを貼り合わせて作成したＰＴＦＥ複合ガラス繊維シートがバグフィルターに使用されている。 Also, a PTFE composite non-woven fabric prepared by laminating a wide PTFE porous sheet and a non-woven fabric is used for an air filter, and a PTFE composite glass fiber sheet prepared by laminating a wide PTFE porous sheet and a glass fiber sheet is provided. Used for bug filters.
　従来の押出成形における肉厚・広幅のＰＴＦＥ多孔質シートを製造するには、熱固定処理前の厚みが５μｍ～１００μｍのシートを複数枚積層し、ＰＴＦＥの融点以上で加熱処理して積層体に加工する必要があった。 In order to produce a porous PTFE sheet having a thickness and width in conventional extrusion molding, a plurality of sheets having a thickness of 5 μm to 100 μm before heat setting are laminated, and heat-treated at a melting point of PTFE or higher to form a laminate. It was necessary to process.
　また、押出成形によらない製法としては、ＰＴＦＥファインパウダーをそのまま擂り潰してパルプ状繊維に加工し、多量の界面活性剤を使用してＰＴＦＥのパルプ状繊維を水中に分散させ、これを抄紙したものを乾燥及び焼結させることによって肉厚及び広幅で長尺のＰＴＦＥ多孔質シートを作成することができたが、複雑で長いプロセスを必要とした。この肉厚及び広幅で長尺のＰＴＦＥ多孔質シートとしては、厚み０．５ｍｍ又は１ｍｍ、幅６０ｃｍのＰＯＬＹＦＬＯＮ（Ｄａｉｋｉｎ　Ｉｎｄｕｔｒｉｅｓ，　Ｌｔｄ．の登録商標）ペーパーが市販されている。 In addition, as a manufacturing method not based on extrusion molding, PTFE fine powder was crushed as it was and processed into pulp-like fibers, and a large amount of surfactant was used to disperse the PTFE pulp-like fibers in water, and paper was made. Thick and wide and long PTFE porous sheets could be made by drying and sintering the material, but required a complex and long process. As this thick, wide and long PTFE porous sheet, POLYFLON (registered trademark of Daikin Industries, Ltd.) paper having a thickness of 0.5 mm or 1 mm and a width of 60 cm is commercially available.
　下記特許文献１について
　当該文献に示される広幅のＰＴＦＥ多孔質シートの製法は、まず押出方向の延伸を行い、続いて幅方向の延伸を行い、その後、熱固定処理する製法である。この製法により広幅のＰＴＦＥ多孔質シートを得るために、延伸前にペースト押出されたシートを２００μｍ前後の厚みに圧延して圧延シートを作成し、このシートを出発材料として押出方向に延伸した後に幅方向に延伸しなければ、面積倍率で１００～２００倍を超える広幅のＰＴＦＥ多孔質シートは得られなかった。このようにＰＴＦＥの長尺シートを幅方向に延伸する製法としては、ＰＴＦＥの長尺シートを押出方向に延伸した後に幅方向に延伸する製法に限られており、厚みが２００μｍ以下の広幅のＰＴＦＥ多孔質シートのみであった。 About the following patent document 1 The manufacturing method of the wide PTFE porous sheet shown by the said literature is a manufacturing method which performs extending | stretching of an extrusion direction first, followed by extending | stretching of a width direction, and heat-processing after that. In order to obtain a wide PTFE porous sheet by this manufacturing method, a sheet extruded with a paste before stretching is rolled to a thickness of about 200 μm to create a rolled sheet, and then the sheet is stretched in the extrusion direction using the sheet as a starting material. Without stretching in the direction, a PTFE porous sheet having a width exceeding 100 to 200 times in area magnification could not be obtained. As described above, the production method of stretching the long sheet of PTFE in the width direction is limited to the production method of stretching the long sheet of PTFE in the extrusion direction and then stretching in the width direction, and a wide PTFE having a thickness of 200 μm or less. It was only a porous sheet.
　上記の製法は、下記特許文献２に記載の、ＰＴＦＥペースト押出成形体から製造されるＰＴＦＥ多孔質構造体やＰＴＦＥ多孔質シートに関する製法をよりどころとしている。例えば、特許文献２の実施例によれば、長尺シートの幅方向の伸張条件を、温度５０℃、延伸速度比率５００％／秒とすれば多孔質シートが作成でき、温度２２５℃、延伸速度比率５％／秒では破断して多孔質シートが作成されないとされており、幅方向のみの延伸は極めて限定された伸張条件の下でなければ困難であった。さらに、特許文献２における「例９」に、延伸した後の熱処理されていない延伸フィルムを交互に積層し、融点以上で熱処理して厚み０．５ｍｍ以上のＰＴＦＥ多孔質シートを得る方法が示されている。このような方法で厚みを０．５ｍｍ以上にしたＨＹＰＥＲ－ＳＨＥＥＴ（Ｗ．Ｌ．Ｇｏｒｅ　＆　Ａｓｓｏｃｉａｔｅｓの登録商標）が市販されている。 The above manufacturing method is based on the manufacturing method related to the PTFE porous structure and PTFE porous sheet manufactured from the PTFE paste extrusion-molded body described in Patent Document 2 below. For example, according to the example of Patent Document 2, a porous sheet can be produced by setting the stretching condition in the width direction of a long sheet to a temperature of 50 ° C. and a stretching speed ratio of 500% / second, and a temperature of 225 ° C. and a stretching speed. At a rate of 5% / second, it is considered that a porous sheet is not formed by breaking, and stretching in the width direction is difficult unless it is under extremely limited stretching conditions. Further, “Example 9” in Patent Document 2 shows a method of alternately laminating stretched films that have not been heat-treated after being stretched and heat-treating them at a melting point or higher to obtain a PTFE porous sheet having a thickness of 0.5 mm or more. ing. HYPER-SHEET (registered trademark of WL Gore & Associates) having a thickness of 0.5 mm or more by such a method is commercially available.
　下記特許文献３について
　当該文献には、長尺シートの幅方向の延伸が成形助剤存在下で行うことができることが示されている。この成形助剤を含んだ状態で延伸を行う方法は、幅方向延伸後に成形助剤の除去工程、すなわち成形助剤乾燥・抽出工程後、再び延伸を行う方法である。成形助剤存在下ではＰＴＦＥは多孔質にはならないために、このような面倒な工程を経ることになる。 About the following patent document 3 The said document shows that extending | stretching of the width direction of a elongate sheet | seat can be performed in the presence of a shaping | molding adjuvant. The method of stretching in a state containing the molding aid is a method of performing stretching again after the widthwise stretching after the molding aid removing step, that is, the molding aid drying / extraction step. In the presence of a molding aid, PTFE does not become porous, and thus undergoes such a troublesome process.
　下記特許文献４及び特許文献５について
　特許文献４には、積層予備成形体を押出す方法として、第２の結晶性ポリマーシート層が第１の結晶性ポリマーシート層で被覆されてなる積層予備成形体を押出方向に押出す方法において、成形金型を用いて積層予備成形体を押出す方法が示され、積層予備成形体の押出す温度としては１９℃～２００℃が好ましいことが開示されている。 Regarding Patent Document 4 and Patent Document 5 described below, Patent Document 4 describes a method for extruding a laminated preform, in which a second crystalline polymer sheet layer is coated with a first crystalline polymer sheet layer. In the method of extruding the body in the extrusion direction, a method of extruding a laminated preform using a molding die is shown, and it is disclosed that the extrusion temperature of the laminated preform is preferably 19 ° C. to 200 ° C. Yes.
　特許文献５には、積層体を形成する際の押出し方法としては、公知のペースト押出装置を用いる方法が示され、積層体を形成する際の押出しに用いるペースト押出装置のシリンダー部の形状として、軸直角方向断面が５０ｍｍ×１００ｍｍの矩形であり、出口部でシリンダー部の一方が絞られたノズル５０ｍｍ×５ｍｍで構成される形状が示され、積層体を形成する際の押出し温度としては１９℃～２００℃で行うことが好ましく、積層体を形成する際の押出し形状としては棒状が好ましく、シート状がより好ましいことが開示されている。 Patent Document 5 shows a method of using a known paste extrusion device as an extrusion method when forming a laminate, and the shape of the cylinder part of the paste extrusion device used for extrusion when forming a laminate, The cross-section in the direction perpendicular to the axis is a rectangle of 50 mm × 100 mm, and a shape composed of a nozzle 50 mm × 5 mm in which one of the cylinder portions is narrowed at the outlet is shown, and the extrusion temperature when forming the laminate is 19 ° C. It is disclosed that it is preferably carried out at ˜200 ° C., and it is disclosed that the extrusion shape when forming the laminate is preferably a rod shape and more preferably a sheet shape.
　このように、特許文献４及び５においては押出成形シートの助剤除去後に当該シートを幅方向に延伸することは開示されていない。しかし、押出シートを０．２ｍｍ以下に圧延し、助剤除去後に特許文献１と同様な延伸を行うことが示されている。 Thus, Patent Documents 4 and 5 do not disclose that the sheet is stretched in the width direction after the auxiliary agent is removed from the extruded sheet. However, it is shown that the extruded sheet is rolled to 0.2 mm or less, and the same stretching as in Patent Document 1 is performed after the auxiliary agent is removed.
　下記特許文献６について
　当該文献には、次のような成形金型に関する記載がある。すなわち、予備成形体投入部と、該予備成形体投入部に接続された絞り部と、該絞り部に接続された中心角度が８０°以上の扇部とからなる成形金型を備えた押出装置により、予備成形体をシート状に押出す工程が記載されている。 About the following patent document 6 The said document has the description regarding the following molding dies. That is, an extrusion apparatus provided with a molding die comprising a preformed body charging part, a throttle part connected to the preformed part charging part, and a fan part having a central angle of 80 ° or more connected to the throttle part Describes the process of extruding the preform into a sheet.
　押出工程で用いる押出装置における予備成形体投入部の断面積と、絞り部における最小断面積との絞り比は、押出装置における予備成形体投入部の断面積Ａ１と、絞り部における最小断面積Ａ２との比（Ａ１／Ａ２）により表される。押出工程で用いる押出装置の絞り比を低くすることにより、予備成形体を低せん断で押出すことができ、柔軟性を有する結晶性ポリマーからなるシートを得ることができる。押出工程で用いる押出装置における絞り比としては１６以下が好ましく、１６を超えると、予備成形体を高せん断で押出すことになり、押出物の柔軟性が得られず、高倍率での延伸ができないため、微小な孔径を有する結晶性ポリマーを作製することができないことがある。一方、絞り比が８～１４であると、予備成形体を低せん断で押出すことができ、押出物の柔軟性が得られることから、高倍率での延伸が可能となり、微小な孔径を有する結晶性ポリマーを作製することができる。 The drawing ratio between the cross-sectional area of the preformed body input portion in the extrusion apparatus used in the extrusion process and the minimum cross-sectional area of the drawn portion is the cross-sectional area A1 of the preformed body input portion in the extruder and the minimum cross-sectional area A2 of the drawn portion. And the ratio (A1 / A2). By reducing the drawing ratio of the extrusion apparatus used in the extrusion process, the preform can be extruded with low shear, and a sheet made of a crystalline polymer having flexibility can be obtained. The drawing ratio in the extrusion apparatus used in the extrusion process is preferably 16 or less, and if it exceeds 16, the preform is extruded at high shear, the flexibility of the extrudate cannot be obtained, and stretching at a high magnification is possible. Since it is not possible, a crystalline polymer having a minute pore size may not be produced. On the other hand, if the drawing ratio is 8 to 14, the preform can be extruded with low shear, and the flexibility of the extrudate can be obtained, so that it can be stretched at a high magnification and has a fine pore size. Crystalline polymers can be made.
　扇部の中心角度を８０°以上１６０°以下とすることにより、予備成形体を低せん断で押出すことができ、柔軟性を有する結晶性ポリマーからなるシートを得ることができる。前記中心角度が８０°未満であると、必要なサンプル幅を確保するため押出口までの距離が長くなり押出物にせん断がかかるため、押出物の柔軟性が得られず、高倍率での延伸ができないので、微小な孔径を有する結晶性ポリマーを作製することができないことがある。中心角度が１６０°を超えると、幅方向の均一な押出が困難なことがある。一方、中心角度が９０°以上１４０°以下であると、扇部における最上部から扇部の出口幅までの距離が適切となるため、予備成形体を低せん断で押出すことができ、押出物の柔軟性が得られることから、高倍率での延伸が可能となり、微小な孔径を有する結晶性ポリマーを作製することができる。 By setting the center angle of the fan part to 80 ° or more and 160 ° or less, the preform can be extruded with low shear, and a sheet made of a crystalline polymer having flexibility can be obtained. If the center angle is less than 80 °, the distance to the extrusion port is increased to ensure the necessary sample width, and the extrudate is sheared, so the flexibility of the extrudate cannot be obtained and stretching at a high magnification. Therefore, it may not be possible to produce a crystalline polymer having a minute pore size. When the center angle exceeds 160 °, uniform extrusion in the width direction may be difficult. On the other hand, if the center angle is 90 ° or more and 140 ° or less, the distance from the uppermost part of the fan part to the outlet width of the fan part becomes appropriate, so the preform can be extruded with low shear, and the extrudate Therefore, it is possible to stretch at a high magnification, and it is possible to produce a crystalline polymer having a minute pore size.
　押出工程で用いる押出装置における扇部の出口幅は、押出装置における予備成形体の押出幅となる。前記扇部の出口幅を１５０ｍｍ～５００ｍｍとすることにより、予備成形体を低せん断で押出すことができ、柔軟性を有する結晶性ポリマーからなるシートを得ることができる。扇部の出口幅が１５０ｍｍ未満であると、安定した延伸ができないことがある。扇部の出口幅が５００ｍｍを超えると、扇部における最上部から扇部の出口幅までの距離が長くなるため、予備成形体を高せん断で押出すことになり、押出物の柔軟性が得られず、高倍率での延伸ができないので、微小な孔径を有する結晶性ポリマーを作製することができないことがある。一方、前記扇部の出口幅が２００ｍｍ～４００ｍｍであると、扇部における最上部から扇部の出口幅までの距離が適切となるため、予備成形体を低せん断で押出すことができ、押出物の柔軟性が得られることから、高倍率での延伸が可能となり、微小な孔径を有する結晶性ポリマーを作製することができる。 The exit width of the fan part in the extrusion device used in the extrusion process is the extrusion width of the preform in the extrusion device. By setting the outlet width of the fan section to 150 mm to 500 mm, the preform can be extruded with low shear, and a sheet made of a crystalline polymer having flexibility can be obtained. If the exit width of the fan part is less than 150 mm, stable stretching may not be possible. If the outlet width of the fan part exceeds 500 mm, the distance from the uppermost part of the fan part to the outlet width of the fan part becomes longer, so that the preform is extruded at high shear, and the flexibility of the extrudate is obtained. In other words, since it cannot be stretched at a high magnification, it may not be possible to produce a crystalline polymer having a minute pore size. On the other hand, when the outlet width of the fan part is 200 mm to 400 mm, the distance from the uppermost part of the fan part to the outlet width of the fan part is appropriate, so that the preform can be extruded with low shear. Since the flexibility of the product can be obtained, it is possible to stretch at a high magnification, and it is possible to produce a crystalline polymer having a minute pore size.
　押出工程における押出方法としては、押出装置により、１９℃～２００℃の温度にて予備成形体を押出す方法が好ましい。 As the extrusion method in the extrusion step, a method of extruding the preform at a temperature of 19 ° C. to 200 ° C. with an extruder is preferable.
　押出す際の形状としては棒状が好ましく、シート状がより好ましい。押出工程により得られた結晶性ポリマーからなるシートの厚みとしては５０μｍ～２５０μｍが好ましく、５０μｍ未満であると、製膜中に破断することがあり、２５０μｍを超えると、圧延機に対する負荷がかかりすぎることがある。なお、厚みが８０μｍ～２００μｍであると、多段圧延適性の点で有利であることが記載されている。 As the shape at the time of extrusion, a rod shape is preferable, and a sheet shape is more preferable. The thickness of the sheet made of the crystalline polymer obtained by the extrusion process is preferably 50 μm to 250 μm. If it is less than 50 μm, it may break during film formation. If it exceeds 250 μm, too much load is applied to the rolling mill. Sometimes. It is described that a thickness of 80 μm to 200 μm is advantageous in terms of suitability for multi-stage rolling.
　このように特許文献６には、予備成形体投入部と、該予備成形体投入部に接続された絞り部と、該絞り部と接続され、中心角度が８０°以上の扇部とを有する成形金型が開示されており、成形金型における予備成形体投入部の断面積と、絞り部における最小断面積との絞り比が１６以下、扇部の出口幅が１５０ｍｍ～５００ｍｍ、押出装置による前記予備成形体を押出す温度が１９℃～２００℃、押出工程により得られた結晶性ポリマーからなるシートの厚みが５０μｍ～２５０μｍとすることが開示されている。 As described above, Patent Document 6 discloses a molding including a preformed body charging portion, a throttle portion connected to the preformed body charging portion, and a fan portion connected to the throttle portion and having a central angle of 80 ° or more. A mold is disclosed, the drawing ratio of the cross-sectional area of the preformed body input portion in the molding die to the minimum cross-sectional area of the drawn portion is 16 or less, the exit width of the fan portion is 150 mm to 500 mm, It is disclosed that the temperature for extruding the preform is 19 ° C. to 200 ° C., and the thickness of the sheet made of the crystalline polymer obtained by the extrusion process is 50 μm to 250 μm.
　下記特許文献７について
　当該文献には、次のような成形金型に関する記載がある。すなわち、予備成形体を投入する予備成形体投入部と、該予備成形体投入部における下流側に接続された絞り部と、該絞り部における下流側に接続された中心角度が３０°以上８０°未満、出口幅が２００ｍｍ以上である扇部とからなり、予備成形体投入部における押出方向と直交方向の最大断面積と、絞り部における押出方向と直交方向の最小断面積との絞り比が５０以上である成形金型を備えた押出装置を用いて、予備成形体をシート状に押出す工程が記載されている。 About the following patent document 7 The said document has the description regarding the following molding dies. That is, a preformed body charging part for charging the preformed body, a throttle part connected to the downstream side of the preformed body charging part, and a central angle connected to the downstream side of the throttle part of 30 ° or more and 80 ° Less than 200 mm and the exit width is 200 mm or more, and the drawing ratio of the maximum cross-sectional area in the direction orthogonal to the extrusion direction and the minimum cross-sectional area in the direction orthogonal to the extrusion direction in the drawing part is 50. The process of extruding a preform into a sheet using the extrusion apparatus provided with the molding die as described above is described.
　前記絞り比が５０以上８００未満であると、プレス圧が過剰になることなく予備成形体の送り方向、厚み方向、幅方向の全てに対し高せん断を印加しながら押出すことができ、強靭な結晶性ポリマーからなるシートを得ることができるため、従来ではできないとされていた押出しとカレンダーロールによる圧延のみで、平均厚みが５０μｍ以下の結晶性ポリマー微孔性膜の製造が可能となる。 When the drawing ratio is 50 or more and less than 800, extrusion can be performed while applying high shear to all of the feeding direction, thickness direction, and width direction of the preform without excessive press pressure. Since a sheet made of a crystalline polymer can be obtained, a crystalline polymer microporous film having an average thickness of 50 μm or less can be produced only by extrusion and rolling with a calender roll, which had been impossible in the past.
　扇部の中心角度が、過剰に広いとシートに裂けを生じやすく、過剰に狭いとせん断を与えるために必要な横方向の変形を与えるための長大な金型が必要となり押出し圧が上昇し、実質的に利用不可能な押出圧となるおそれがある。 If the center angle of the fan part is excessively wide, the sheet is liable to tear, and if it is excessively narrow, a long mold is required to give the lateral deformation necessary to give shear, and the extrusion pressure rises. There is a risk that the extrusion pressure may be substantially unusable.
　前記扇部の出口幅は、該扇部の出口開口長さ乃至幅をいい、扇部における下流出口の幅方向が一定の値となる幅をいう。扇部の出口幅が不足すると十分なせん断を与えることができず、過剰に広いとシートに裂けを生じるか又は押出し圧が過剰となって適正な押出しが行えないおそれが生じる。 The outlet width of the fan portion refers to the outlet opening length or width of the fan portion, and refers to a width in which the width direction of the downstream outlet in the fan portion is a constant value. When the outlet width of the fan part is insufficient, sufficient shearing cannot be applied, and when it is excessively wide, there is a possibility that the sheet is torn or the extrusion pressure is excessive and proper extrusion cannot be performed.
　前記扇部の中心角度３０°以上７５°以下及び出口幅２００ｍｍ以上６００ｍｍ以下であると、予備成形体に対し、絞り比のせん断効果に加えて更に幅方向に高いせん断力を印加することが可能になる。 When the center angle of the fan part is 30 ° or more and 75 ° or less and the outlet width is 200 mm or more and 600 mm or less, it is possible to apply a higher shearing force in the width direction to the preform in addition to the shearing effect of the drawing ratio. become.
　押出装置の前記出口下部の平均厚みにより、押出しによって得られるシート状成型体の厚みを規定することができ、このシート状成型体の厚みを適宜設定することにより、押出工程及び圧延工程をよりスムーズに行うことが可能である。扇部における下流出口の平均厚みとしては０．５ｍｍ以上３．０ｍｍ以下が好ましく、前記予備成形体を高せん断かつ円滑に押出すことができる。 The thickness of the sheet-like molded body obtained by extrusion can be defined by the average thickness at the lower part of the outlet of the extrusion apparatus. By appropriately setting the thickness of the sheet-like molded body, the extrusion process and the rolling process can be performed more smoothly. Can be done. The average thickness of the downstream outlet in the fan is preferably 0.5 mm or more and 3.0 mm or less, and the preform can be extruded with high shear and smoothness.
　押出装置における予備成形体の押出速度としては０．５ｍ／分～１０．０ｍ／分が好ましく、前記予備成形体を高せん断かつ円滑に押出すことができる。 The extrusion speed of the preform in the extruder is preferably 0.5 m / min to 10.0 m / min, and the preform can be extruded with high shear and smoothness.
　押出工程における押出温度としては、形状安定性の点で、３０℃以上６０℃以下が好ましく、前記予備成形体を高せん断かつ円滑に押出すことができる。 The extrusion temperature in the extrusion step is preferably 30 ° C. or more and 60 ° C. or less from the viewpoint of shape stability, and the preform can be extruded with high shear and smoothness.
　押出工程により得られた結晶性ポリマーからなるシートは、送り方向、幅方向、及び厚み方向の全方向に対して高せん断が印加され、強靭な結晶性ポリマーからなるシートとなり、その強靭さは規定引張り倍率における強度によって表現することができる。押出工程により得られた結晶性ポリマーからなるシートの幅方向の引張り倍率１，０００％にするには６ＭＰａ以上の引張り強度が好ましい。 A sheet made of a crystalline polymer obtained by an extrusion process is a sheet made of a tough crystalline polymer with high shear applied to all directions of the feeding direction, the width direction, and the thickness direction, and the toughness is defined. It can be expressed by the strength at the tensile magnification. A tensile strength of 6 MPa or more is preferable in order to obtain a tensile ratio of 1,000% in the width direction of the sheet made of the crystalline polymer obtained by the extrusion process.
　このように特許文献７には、予備成形体を投入する予備成形体投入部と、該予備成形体投入部における下流側に接続された絞り部と、該絞り部における下流側に接続され、かつ中心角度が３０°以上８０°未満、出口幅が２００ｍｍ以上である扇部とを有してなる成形金型が開示されており、予備成形体投入部における押出方向と直交方向の最大断面積と、絞り部における押出方向と直交方向の最小断面積との絞り比が５０以上、扇部の出口幅は２００ｍｍ以上、扇部出口の平均厚みは０．５ｍｍ以上３．０ｍｍ以下、予備成形体の押出速度が０．５ｍ／分～１０．０ｍ／分、押出工程における押出温度が３０℃以上６０℃以下、押出工程により得られた結晶性ポリマーからなるシートの幅方向の１，０００％引張り強度が６ＭＰａ以上とすることにより、押出しとカレンダーロールによる圧延のみで平均厚みが５０μｍ以下の結晶性ポリマー微孔性膜の製造が可能であることが開示されている。 Thus, in Patent Document 7, a preformed body charging part for charging a preformed body, a throttle part connected to the downstream side of the preformed body charging part, connected to a downstream side of the throttle part, and There is disclosed a molding die having a fan part having a central angle of 30 ° or more and less than 80 ° and an exit width of 200 mm or more, and a maximum cross-sectional area in the direction orthogonal to the extrusion direction in the preformed body charging part The drawing ratio of the extrusion direction and the minimum cross-sectional area in the orthogonal direction in the drawing part is 50 or more, the outlet width of the fan part is 200 mm or more, the average thickness of the fan part outlet is 0.5 mm or more and 3.0 mm or less, Extrusion speed of 0.5 m / min to 10.0 m / min, extrusion temperature in extrusion process of 30 ° C. or more and 60 ° C. or less, 1,000% tensile strength in width direction of sheet made of crystalline polymer obtained by extrusion process Is 6 MPa or more Thus, it is disclosed that a crystalline polymer microporous film having an average thickness of 50 μm or less can be produced only by extrusion and rolling by a calender roll.
特開２００７－２６０５４７号公報JP 2007-260547 A 特開昭５１－３０２７７号公報Japanese Patent Laid-Open No. 51-30277 特開２００９－２４０４０号公報JP 2009-24040 A 特開２０１２－１９２３０８号公報JP 2012-192308 A 特開２０１２－１３９６２４号公報JP 2012-139624 A 特開２０１２－１７２０８５号公報JP 2012-172805 A 特開２０１２－２０６１１３号公報JP 2012-206113 A
　上記のように従来の広幅のＰＴＦＥ多孔質シートの製造方法は、そのほとんどが、まず押出成形シートを押出方向に延伸し、次に押出成形シートを幅方向に延伸するという製造方法に限定されていた。 As described above, most of the conventional methods for producing a wide PTFE porous sheet are limited to a production method in which an extruded sheet is first stretched in the extrusion direction and then the extruded sheet is stretched in the width direction. It was.
　また、上記特許文献６に記載の発明は、押出工程により絞り比が１６以下である成形金型を使用して、厚みが５０μｍ～２５０μｍの結晶性ポリマーのシートを製造することを目的とするものであり、０．５ｍｍ以上の厚みがあり、広幅で長尺のＰＴＦＥ多孔質シートを製造することは考慮されていない発明である。 Further, the invention described in Patent Document 6 is intended to produce a crystalline polymer sheet having a thickness of 50 μm to 250 μm using a molding die having a drawing ratio of 16 or less by an extrusion process. It is an invention that is not considered to produce a wide and long PTFE porous sheet having a thickness of 0.5 mm or more.
　さらに、特許文献７に記載の押出成形シートは、絞り比が５０以上であり、扇部出口の平均厚みが０．５ｍｍ以上３．０ｍｍ以下の成形金型を使用して０．５ｍｍ以上３．０ｍｍ以下の押出成形シートを得ることができるものであるが、この０．５ｍｍ以上３．０ｍｍ以下の押出成形シートの状態で押出方向の延伸を行う前に幅方向の延伸ができる記載はなく、絞り比が５０以上であるため、実際には押出方向に延伸する前に幅方向に延伸することができない。また、特許文献７に記載の発明は、押出工程及び圧延工程を経て厚みが５０μｍのシートを製造することを目的とするものであり、０．５ｍｍ以上の厚みがあり、広幅で長尺のＰＴＦＥ多孔質シートを製造することは考慮されていない発明である。 Furthermore, the extrusion-molded sheet described in Patent Document 7 has a drawing ratio of 50 or more, and a molding die having an average thickness of the fan part outlet of 0.5 mm or more and 3.0 mm or less is used. Although it is possible to obtain an extruded sheet of 0 mm or less, there is no description that can be stretched in the width direction before stretching in the extrusion direction in the state of the extruded sheet of 0.5 mm to 3.0 mm, Since the drawing ratio is 50 or more, it cannot actually be stretched in the width direction before stretching in the extrusion direction. The invention described in Patent Document 7 is intended to produce a sheet having a thickness of 50 μm through an extrusion process and a rolling process, and has a thickness of 0.5 mm or more, a wide and long PTFE. Producing a porous sheet is an invention that has not been considered.
　そこで、本発明者は、従来においてＰＴＦＥペースト押出成形品を延伸する最初の方向が押出方向に限られる問題、及び、特許文献７に示される０．５ｍｍ以上３．０ｍｍ以下の押出成形シートが幅方向に延伸できない問題を研究した。 Therefore, the present inventor has a problem that the first direction in which a PTFE paste extrudate is stretched is limited to the extruding direction in the prior art, and an extruded sheet having a width of 0.5 mm or more and 3.0 mm or less shown in Patent Document 7 is wide. The problem of being unable to stretch in the direction was studied.
　その研究の結果、ＰＴＦＥファインパウダーの重合粒子が、図１に示すように、０．２μｍ～０．４μｍの米粒のような楕円球形状をしており、この形状に起因して、ペースト押出による押出成形や圧延ロールによる圧延時においては、重合粒子がその周囲から加圧されながら成形されるため、それによって成形される成形物は、重合粒子の楕円球形状の長径方向が揃うように押出方向や圧延方向に整列してしまうことを発見した。 As a result of the research, polymerized particles of PTFE fine powder have an elliptical spherical shape like rice grains of 0.2 μm to 0.4 μm, as shown in FIG. At the time of extrusion molding or rolling with a rolling roll, the polymer particles are molded while being pressurized from the surroundings. Therefore, the molded product formed by the extrusion direction is such that the major axis direction of the elliptical spherical shape of the polymer particles is aligned. And found to align in the rolling direction.
　上記のことが原因で、成形物の押出方向に重合粒子の配列配向が強く、前記成形物を助剤除去後に幅方向に引っ張ると、図２に示すように、幅方向に繊維状に細かく裂けてしまって幅方向に延伸することができず、押出方向又は圧延方向にしか延伸できないことが判明した。 Due to the above, the polymer particles are strongly aligned in the extrusion direction of the molded product, and when the molded product is pulled in the width direction after removal of the auxiliary agent, as shown in FIG. Thus, it was found that the film could not be stretched in the width direction and could only be stretched in the extrusion direction or the rolling direction.
　なお、配列方向が揃っている重合粒子は単に整列しているのではなく、重合粒子の物理的な結合強度が上がっており、配列方向の延伸作用を受けると、この結合強度により重合粒子の一部は重合粒子間に跨がる極細小繊維のフィブリルに変形し、一部はフィブリルを結節するノードに変化する。その結果、フィブリルとノードとからなる多孔性物品が得られることが知られている。 Note that the polymer particles having the aligned direction are not simply aligned, but the physical bond strength of the polymer particles is increased. The part is deformed into fibrils of ultrafine fibers straddling between the polymer particles, and a part thereof is changed into a node that connects the fibrils. As a result, it is known that a porous article composed of fibrils and nodes can be obtained.
　また、この工程においてシリンダー中空部の断面積とオリフィス中空部の断面積との比が５０：１の絞り比を超えると、オリフィス内での重合粒子が過度に整列することにより粒子間の押出方向の繋がりが大きくなり、オリフィスの断面積よりフラットダイ面積が大きい場合であっても、重合粒子個々の挙動が行われにくくなるので、作成された押出成形シートは、重合粒子が押出方向に整列した状態となるため、結局、押出方向にのみ延伸できるシートしか得られないこととなり、特許文献７に記載の押出成形シートも絞り比が５０以上であるため、幅方向には延伸することができないことが判明した。 Further, in this process, when the ratio of the cross-sectional area of the hollow part of the cylinder and the cross-sectional area of the hollow part of the orifice exceeds the drawing ratio of 50: 1, the polymer particles in the orifice are excessively aligned so that the direction of extrusion between the particles Even when the flat die area is larger than the cross-sectional area of the orifice, the individual behavior of the polymer particles becomes difficult to be performed, so that the produced extruded sheet has the polymer particles aligned in the extrusion direction. As a result, only a sheet that can be stretched only in the extrusion direction can be obtained, and the extrusion sheet described in Patent Document 7 has a drawing ratio of 50 or more, so that it cannot be stretched in the width direction. There was found.
　また、上記の市販されているＰＯＬＹＦＬＯＮペーパー及びＨＹＰＥＲ－ＳＨＥＥＴはドレープ性に欠けており、これらのペーパー及びシートが利用できる範囲は限られるという問題点があった。 Further, the above-mentioned commercially available POLYFLON paper and HYPER-SHEEET lack drapeability, and there is a problem that the range in which these papers and sheets can be used is limited.
　ＰＯＬＹＦＬＯＮペーパーは、ＰＴＦＥの繊維化された短繊維を抄紙する方法で造られ、厚み０．５ｍｍ空孔率７８％のシート及び厚み１ｍｍ空孔率７６％のシートが市販されているが、短繊維の絡みだけなので強度とドレープ性に劣る。 POLYFLON paper is manufactured by a method of making PTFE fiberized short fibers, and a sheet with a thickness of 0.5 mm and a porosity of 78% and a sheet with a thickness of 1 mm and a porosity of 76% are commercially available. It is inferior in strength and drape because it is only entangled.
　また、ＨＹＰＥＲ－ＳＨＥＥＴは、延伸ＰＴＦＥフィルムを、その延伸方向が交互になるように重ねて焼結した多孔質シートである。この多孔質シートは、その比重が０．６ｇ／ｃｃ、ＰＴＦＥの比重が２．１ｇ／ｃｃ～２．２ｇ／ｃｃであることから、空孔率が７１％～７３％であり、この多孔質シートの厚みは０．５ｍｍから１０ｍｍである。しかし、このシートの製法は１０μｍ～２０μｍの薄いフィルムを交互に重ねて製造する方法であるため、製造されるシートの幅及び長さが、製造会社の商品カタログによると最大１．５ｍ×３ｍに制限され、ドレープ性にも劣るものである。 HYPER-SHEET is a porous sheet obtained by laminating and sintering stretched PTFE films so that their stretch directions are alternated. Since this porous sheet has a specific gravity of 0.6 g / cc and a specific gravity of PTFE of 2.1 g / cc to 2.2 g / cc, the porosity is 71% to 73%. The thickness of the sheet is 0.5 mm to 10 mm. However, since this sheet is manufactured by alternately stacking thin films of 10 μm to 20 μm, the width and length of the manufactured sheet can be up to 1.5 m × 3 m according to the product catalog of the manufacturer. It is limited and inferior to drape.
　本発明者は、鋭意研究した結果、ペースト押出成形における前記押出方向に整列している重合粒子を幅方向に変更させて整列させることにより、ペースト押出成形シートを押出方向に延伸することなく幅方向に延伸する方法を見出し、ドレープ性に富んだ広幅及び長尺で、肉厚のＰＴＦＥ多孔質シートを完成するに至ったのである。 As a result of diligent research, the present inventor has changed the width of the polymer particles aligned in the extrusion direction in paste extrusion molding in the width direction, thereby aligning the paste extrusion molded sheet in the width direction without stretching the extrusion direction. As a result, the inventors have found a wide and long, thick and thick PTFE porous sheet having a good draping property.
　本発明に係るＰＴＦＥ多孔質シートの製造方法は、成形助剤を添加したＰＴＦＥパウダーにより予備成形体を作成し、前記予備成形体をペースト押出成形金型内に投入し、当該成形金型内の予備成形体を押し出すラムによって、当該成形金型内の予備成形体を連続的に押し出すことにより押出方向に長尺の押出成形シートを作成し、前記押出成形シートから前記成形助剤を除去することにより成形助剤除去シートを作成し、テンター装置に前記成形助剤除去シートの幅方向両端を固定し、ＰＴＦＥの室温転移温度以上の環境下で当該成形助剤除去シートを幅方向にのみ元の幅の１．２倍～２５倍に延伸することにより幅方向延伸シートを作成し、前記幅方向延伸シートをＰＴＦＥの融点付近の温度で熱固定処理することにより製造されるＰＴＦＥ多孔質シートであり、前記成形金型は、連設されたシリンダー、オリフィス及びフラットダイを備え、前記シリンダーは中空筒状であり、当該シリンダーに連設されている前記オリフィスは中空矩形状であって、当該シリンダー中空部の断面積に対する当該オリフィス中空部の断面積の比が１０：１～３０：１の絞り比であり、前記オリフィス中空部の矩形状断面は長辺の長さが短辺の長さの１～３倍の矩形であり、前記オリフィスの出口である絞り口に連設されている前記フラットダイは、当該オリフィスの絞り口側を基部として扇状に広がる２つの平面と、当該２つの平面の両側端部を連結する側面とにより囲まれ、扇状の円弧側先端に細幅のフラットダイ開口部が形成された中空扇状をなし、当該２つの平面の扇状の基部から円弧側先端に向かって当該２つの平面の間隔が狭くなるように構成されており、前記フラットダイ開口部の開口面積は、前記オリフィスの絞り口の開口面積の１２５％～３００％であり、当該フラットダイ開口部における両側面間の内法長さは１００ｍｍ～５００ｍｍであり、前記２つの平面間の内法長さは１ｍｍ～５ｍｍであることを特徴とする。 In the method for producing a PTFE porous sheet according to the present invention, a preform is prepared from PTFE powder to which a molding aid is added, and the preform is put into a paste extrusion mold, By continuously extruding the preform in the molding die by a ram for extruding the preform, a long extrusion sheet is formed in the extrusion direction, and the molding aid is removed from the extrusion sheet. To form a molding aid removal sheet, fix both ends of the molding aid removal sheet in the tenter device in the width direction, and place the molding aid removal sheet in the width direction only in the environment above the room temperature transition temperature of PTFE. A width direction stretched sheet is prepared by stretching 1.2 times to 25 times the width, and the width direction stretched sheet is heat-set at a temperature near the melting point of PTFE. An FE porous sheet, and the molding die includes a continuous cylinder, an orifice and a flat die, the cylinder has a hollow cylindrical shape, and the orifice connected to the cylinder has a hollow rectangular shape. The ratio of the cross-sectional area of the orifice hollow part to the cross-sectional area of the cylinder hollow part is a reduction ratio of 10: 1 to 30: 1, and the rectangular cross-section of the orifice hollow part has a short long side. The flat die that is a rectangle that is 1 to 3 times the length of the side and that is connected to the orifice that is the outlet of the orifice has two flat surfaces that spread in a fan shape with the orifice side of the orifice as the base, It is surrounded by side surfaces that connect both side ends of the two planes, forms a hollow fan shape with a narrow flat die opening formed at the tip of the fan-shaped arc side, and extends from the fan-shaped base of the two planes to a circle. The distance between the two flat surfaces is narrowed toward the side tip, and the opening area of the flat die opening is 125% to 300% of the opening area of the orifice of the orifice. The internal length between both side surfaces in the die opening is 100 mm to 500 mm, and the internal length between the two planes is 1 mm to 5 mm.
　また、本発明に係るＰＴＦＥ多孔質シートの製造方法は、成形助剤を添加したＰＴＦＥパウダーにより予備成形体を作成し、前記予備成形体をペースト押出成形金型内に投入し、当該成形金型内の予備成形体を押し出すラムによって、当該成形金型内の予備成形体を連続的に押し出すことにより押出方向に長尺の押出成形シートを作成し、前記押出成形シートを圧延ロールにより圧延し、厚みが０．５ｍｍ以上で元の厚みの３５％以上の厚みの圧延シートを作成し、前記圧延シートから成形助剤を除去することにより成形助剤除去圧延シートを作成し、テンター装置に前記成形助剤除去圧延シートの幅方向両端を固定し、ＰＴＦＥの室温転移温度以上の環境下で当該成形助剤除去圧延シートを幅方向にのみ元の幅の１．２倍～２５倍に延伸することにより幅方向延伸圧延シートを作成し、前記幅方向延伸圧延シートをＰＴＦＥの融点付近の温度で熱固定処理することにより製造したされるＰＴＦＥ多孔質シートであり、前記成形金型は、連設されたシリンダー、オリフィス及びフラットダイを備え、前記シリンダーは中空筒状であり、当該シリンダーに連設されている前記オリフィスは中空矩形状であって、当該シリンダー中空部の断面積に対する当該オリフィス中空部の断面積の比が１０：１～３０：１の絞り比であり、前記オリフィス中空部の矩形状断面は長辺の長さが短辺の長さの１～３倍の矩形であり、前記オリフィスの出口である絞り口に連設されている前記フラットダイは、当該オリフィスの絞り口側を基部として扇状に広がる２つの平面と、当該２つの平面の両側端部を連結する側面とにより囲まれ、扇状の円弧側先端に細幅のフラットダイ開口部が形成された中空扇状をなし、当該２つの平面の扇状の基部から円弧側先端に向かって当該２つの平面の間隔が狭くなるように構成されており、前記フラットダイ開口部の開口面積は、前記オリフィスの絞り口の開口面積の１２５％～３００％であり、当該フラットダイ開口部における両側面間の内法長さは１００ｍｍ～５００ｍｍであり、前記２つの平面間の内法長さは１ｍｍ～５ｍｍであることを特徴とする。 Further, the method for producing a porous PTFE sheet according to the present invention comprises preparing a preform from PTFE powder to which a molding aid has been added, putting the preform into a paste extrusion mold, and forming the mold. By continuously extruding the preform in the molding die by a ram for extruding the preform in the inside, a long extrusion sheet is formed in the extrusion direction, and the extrusion sheet is rolled by a rolling roll, A rolled sheet having a thickness of 0.5 mm or more and a thickness of 35% or more of the original thickness is prepared, and a forming aid is removed from the rolled sheet to form a forming aid-removed rolled sheet, and the forming is performed on the tenter device. Fixing both ends in the width direction of the auxiliary agent-removed rolled sheet, and extending the forming auxiliary agent-removed rolled sheet to 1.2 to 25 times the original width only in the width direction in an environment above the room temperature transition temperature of PTFE A PTFE porous sheet produced by preparing a width direction stretched rolled sheet and heat-setting the width direction stretched rolled sheet at a temperature in the vicinity of the melting point of PTFE. Provided with a cylinder, an orifice, and a flat die, and the cylinder has a hollow cylindrical shape. The orifice connected to the cylinder has a hollow rectangular shape, and the orifice hollow with respect to the cross-sectional area of the hollow portion of the cylinder. The ratio of the cross-sectional area of the portion is a drawing ratio of 10: 1 to 30: 1, and the rectangular cross section of the orifice hollow portion is a rectangle whose long side is 1 to 3 times the length of the short side, The flat die connected to the orifice that is the outlet of the orifice has two planes that expand in a fan shape with the orifice side of the orifice as a base, and both sides of the two planes. Are formed in a hollow fan shape in which a narrow flat die opening is formed at the fan-shaped arc side tip, and the two flat fan-shaped bases toward the arc-side tip. The flat die opening is configured such that the opening area of the flat die opening is 125% to 300% of the opening area of the orifice of the orifice, and between the two side surfaces of the flat die opening. The inner length is 100 mm to 500 mm, and the inner length between the two planes is 1 mm to 5 mm.
　本発明のＰＴＦＥ多孔質シートの製造方法によれば、２．５ｍ幅を超える５ｍ幅で０．５ｍｍ以上の厚みのある長尺のＰＴＦＥ多孔質シートを容易に製造することができる。 According to the method for producing a PTFE porous sheet of the present invention, a long PTFE porous sheet having a width of 5 m exceeding 2.5 m and a thickness of 0.5 mm or more can be easily produced.
ＰＴＦＥ重合粒子の電子顕微鏡写真である。2 is an electron micrograph of PTFE polymer particles. シリンダーとオリフィスの断面積比が１００対１（ＲＲ１００）の押出品を幅方向に引張って裂き割った状態を示す写真である。It is a photograph which shows the state which pulled and cracked the extruded product whose cross-sectional area ratio of a cylinder and an orifice is 100 to 1 (RR100). フラットダイの残留成形体を助剤乾燥することで現れた重合粒子の配向状態を示す写真である。It is a photograph which shows the orientation state of the superposition | polymerization particle which appeared by drying the residual molded object of a flat die with auxiliary agent. ペースト押出成形金型におけるシリンダー、オリフィス及びフラットダイが連設した状態を示す概略模式図である。It is a schematic diagram which shows the state in which the cylinder in the paste extrusion molding die, the orifice, and the flat die were connected. ペースト押出成形金型の内部構造を示す写真である。It is a photograph which shows the internal structure of a paste extrusion mold. ＰＴＦＥペースト押出の成形状態を示す写真である。It is a photograph which shows the shaping | molding state of PTFE paste extrusion. ＰＴＦＥペースト押出の成形状態の立体写真である。It is a three-dimensional photograph of the molding state of PTFE paste extrusion. 図３の写真に関して、フラットダイにおけるＰＴＦＥ重合粒子を巨視化した整列配向の概念図である。FIG. 4 is a conceptual diagram of aligned orientation in which PTFE polymer particles in a flat die are macroscopically related to the photograph of FIG. 3. 延伸試験器具の写真である。It is a photograph of an extension test instrument. 延伸試験器具に押出成形シートを固定側クリップおよび可動側クリップにより固定した状態を示す写真である。It is a photograph which shows the state which fixed the extrusion sheet | seat to the extending | stretching test instrument with the fixed side clip and the movable side clip. 延伸試験器具により６倍延伸品を作成した状態を示す写真である。It is a photograph which shows the state which produced the 6 times extending | stretching product with the extending | stretching test instrument. 実施例３のＰＴＦＥ多孔質シートとＰＯＬＹＦＬＯＮペーパーとのドレープ性を比較した写真である。It is the photograph which compared the drape property of the PTFE porous sheet of Example 3, and POLYFLON paper. 実施例３のＰＴＦＥ多孔質シートとＨＹＰＥＲ－ＳＨＥＥＴとのドレープ性を比較した写真である。4 is a photograph comparing the drape properties of the PTFE porous sheet of Example 3 and HYPER-SHEEET.
　本発明の実施形態に係る前記ＰＴＦＥファインパウダーは、数平均分子量４００万以上のホモ系重合品が好ましい。 The PTFE fine powder according to an embodiment of the present invention is preferably a homopolymer product having a number average molecular weight of 4 million or more.
　本発明の実施形態に係る前記成形金型におけるシリンダーは、中空形状であれば、その内面形状は特に限定されず、断面円形であっても断面矩形であってもよい。前記のオリフィス中空部の断面が長方形の場合、フラットダイとの連設はオリフィス中空部の断面の長方形の辺の長い方が、フラットダイに直交する方向とするか、又は平行な方向とするかのいずれでもよい。また、シリンダー中空部の断面積に対するオリフィス中空部の断面積の絞り比は１０：１～３０：１とする。前記のフラットダイ開口部の開口面積は、当該フラットダイ開口部における両側面間の内法長さと前記２つの平面間の内法長さとの積となる。 The inner surface of the cylinder in the molding die according to the embodiment of the present invention is not particularly limited as long as it is hollow, and may be circular in cross section or rectangular in cross section. When the cross section of the orifice hollow part is rectangular, whether the longer side of the rectangular side of the cross section of the orifice hollow part is in a direction perpendicular to the flat die or in a parallel direction. Either of these may be used. In addition, the drawing ratio of the cross-sectional area of the orifice hollow part to the cross-sectional area of the cylinder hollow part is 10: 1 to 30: 1. The opening area of the flat die opening is the product of the internal length between both side surfaces of the flat die opening and the internal length between the two planes.
　本発明の実施形態に係る押出成形シートを作成する手段は、図４及び図５に示すように、連設されたシリンダー、オリフィス及びフラットダイを備えるペースト押出成形金型の構造にあり、シリンダー、オリフィス及びフラットダイの相関関係にある。 As shown in FIGS. 4 and 5, the means for producing the extrusion sheet according to the embodiment of the present invention is in the structure of a paste extrusion mold including a cylinder, an orifice, and a flat die arranged in series, Correlation of orifice and flat die.
　金型の三つの部分の役割は、シリンダーが予備成形体を挿入する場所であり、図８に示すように、シリンダー内の重合粒子が並ぶ方向はまったくランダムであり、予備成形体の入り口方向からラムによって押出作用を受け、ついでＰＴＦＥ重合粒子はオリフィスで押出方向に整列する作用を受ける。 The role of the three parts of the mold is where the cylinder inserts the preform, and as shown in FIG. 8, the direction in which the polymer particles in the cylinder are arranged is completely random, and from the entrance direction of the preform. The ram undergoes an extruding action, and then the PTFE polymer particles undergo an action of aligning in the extruding direction at the orifice.
　続いて扇状に広がるフラットダイに進み、このフラットダイに進むところでオリフィスの絞り口の開口面積よりフラットダイ開口部の開口面積を大きくすることによって、かつ、オリフィスの絞り比が３０以下であることによって、オリフィスの絞り口では押出方向に整列していた重合粒子の整列が崩れて幅方向に向きを変えて整列するので、幅方向に延伸することができる。図８において、右上に表した模式図は、左の図における（Ｓ１）の部分を表し、右中間に表した模式図は、左の図における（Ｓ２）の部分を表し、右下に表した模式図は、左の図における（Ｓ３）の部分を表す。このように変化する状態を図３、図６及び図７に示す。 Subsequently, the process proceeds to a flat die that spreads in a fan shape, where the opening area of the flat die opening is made larger than the opening area of the orifice of the orifice at the point of proceeding to this flat die, and the orifice drawing ratio is 30 or less. In addition, since the alignment of the polymer particles aligned in the extrusion direction is broken at the orifice of the orifice and changed in the width direction, it can be stretched in the width direction. In FIG. 8, the schematic diagram shown in the upper right represents the part (S1) in the left diagram, and the schematic diagram represented in the middle right represents the part (S2) in the left diagram and represented in the lower right. The schematic diagram represents a portion (S3) in the left diagram. The state changing in this way is shown in FIGS.
　前記フラットダイ開口部の面積は、前記オリフィスの絞り口の開口面積の１２５％～３００％とする。逆にオリフィスの絞り口の開口面積よりフラットダイ開口部の開口面積が小さいと、フラットダイの内部で重合粒子はさらに押出方向に整列し、重合粒子の整列方向が押出方向のままとなるので、幅方向に延伸することができなくなる。 The area of the flat die opening is 125% to 300% of the opening area of the orifice of the orifice. Conversely, if the opening area of the flat die opening is smaller than the opening area of the orifice of the orifice, the polymer particles are further aligned in the extrusion direction inside the flat die, and the alignment direction of the polymer particles remains in the extrusion direction. It becomes impossible to stretch in the width direction.
　また、フラットダイ開口部の隙間、すなわちフラットダイ開口部における２つの平面間の内法長さが１ｍｍ未満になると、フラットダイ開口部における壁間抵抗のために重合粒子が押出方向に整列させられてしまうので、幅方向の延伸を行うことができなくなる。 When the gap between the flat die openings, that is, the inner length between two planes in the flat die openings is less than 1 mm, the polymer particles are aligned in the extrusion direction due to the resistance between the walls in the flat die openings. Therefore, stretching in the width direction cannot be performed.
　本発明の実施形態に係る前記ＰＴＦＥ多孔質シートの厚みは、フラットダイ開口部における２つの平面間の内法長さの設定によって決まるが、最小限１ｍｍから最大限５ｍｍである。 The thickness of the PTFE porous sheet according to the embodiment of the present invention is determined by setting an internal length between two planes in the flat die opening, and is a minimum of 1 mm to a maximum of 5 mm.
　本発明の実施形態に係る前記の圧延ロールにより圧延される最小限の厚みは、ペースト押出成形金型によって押出された押出成形シートの厚みの３５％までに圧延されたシートに限られる。フラットダイ開口部における２つの平面間の内法長さが１．５ｍｍの場合における押出成形シートは圧延により約０．５ｍｍまで圧延することができる。また、本発明で押出成形された助剤含有シートを圧延ロールで元の厚みの３５％までに圧延した場合には、助剤除去後の助剤除去シートは幅方向に延伸することが可能となる。元の厚みの３５％未満の厚みまで圧延すると幅方向に延伸できなくなる。 The minimum thickness rolled by the rolling roll according to the embodiment of the present invention is limited to a sheet rolled up to 35% of the thickness of the extruded sheet extruded by the paste extrusion mold. When the inner length between two planes at the flat die opening is 1.5 mm, the extruded sheet can be rolled to about 0.5 mm. In addition, when the auxiliary agent-containing sheet extruded by the present invention is rolled to 35% of the original thickness with a rolling roll, the auxiliary agent removal sheet after removal of the auxiliary agent can be stretched in the width direction. Become. If it is rolled to a thickness of less than 35% of the original thickness, it cannot be stretched in the width direction.
　本発明の実施形態に係る幅方向の延伸に使用する前記テンター装置としては、シートの厚みが自由に変えられる点で、シートの両端を差し込んで把持するピンを採用している形式のピンテンターが好ましい。なお、シートの幅長さの上限はテンター装置の問題であるが、幅５ｍを超えるテンター装置が使用されている。また、ＰＴＦＥ多孔質シートとしては、幅約２００ｍｍから１０倍前後に延伸された幅２５００ｍｍの二軸延伸シートが製造されているので、幅５００ｍｍの成形押出シートから１０倍の幅５ｍのＰＴＦＥ多孔室質シートを作成することが可能である。 The tenter device used for stretching in the width direction according to the embodiment of the present invention is preferably a pin tenter that employs pins that insert and hold both ends of the sheet in that the thickness of the sheet can be freely changed. . The upper limit of the width of the sheet is a problem of the tenter device, but a tenter device having a width exceeding 5 m is used. In addition, as the PTFE porous sheet, a biaxially stretched sheet having a width of 2500 mm that is stretched about 200 mm to about 10 times is manufactured. Therefore, a PTFE porous chamber having a width of 10 m and a width of 5 m is formed from a molded extruded sheet having a width of 500 mm. It is possible to create a quality sheet.
　前記の幅方向に延伸する際の延伸温度として記載したＰＴＦＥの室温転移温度とは、示差走査熱量計で測定される吸収ピークの温度が室温の１９℃～２１℃に存在する転移温度のことを意味する。実際の延伸温度はコントロールされるべきであり、５０℃以上、好ましくは１００℃以上である。このようにして押出成形シートを幅方向に延伸を行うことにより肉厚・幅広の長尺シートが得られる。 The room temperature transition temperature of PTFE described as the stretching temperature at the time of stretching in the width direction is the transition temperature at which the absorption peak temperature measured with a differential scanning calorimeter is between 19 ° C. and 21 ° C. of room temperature. means. The actual stretching temperature should be controlled and is 50 ° C. or higher, preferably 100 ° C. or higher. Thus, a long sheet having a large thickness and a wide width is obtained by stretching the extruded sheet in the width direction.
　本発明の実施形態に係る前記の押出成形シート又は圧延シートは、これを幅方向に延伸を行った後、熱固定処理をしていない状態でシートの押出方向に１．２倍以上に延伸して２軸延伸シートとした後に熱固定処理してＰＴＦＥ多孔質シートを得ることができる。押出方向の延伸倍率は最大２５倍である。 The extruded sheet or rolled sheet according to the embodiment of the present invention is stretched in the width direction and then stretched 1.2 times or more in the sheet extruding direction without being heat-set. The biaxially stretched sheet can be heat-set to obtain a PTFE porous sheet. The draw ratio in the extrusion direction is a maximum of 25 times.
　前記の熱固定処理は、通常ＰＴＦＥの融点以上で行うが、それに限定されず融点より低く、延伸温度より５０℃以上高い温度で熱処理してもよい。 The heat setting treatment is usually performed at a melting point of PTFE or higher, but is not limited thereto, and may be heat-treated at a temperature lower than the melting point and 50 ° C. higher than the stretching temperature.
　前記のドレープ性を有するＰＴＦＥ多孔質シートの例としては、厚みが１ｍｍで空孔率が７０％～７５％のＰＴＦＥ多孔質シートの場合は、水平状態から垂下し始めるまでのシートの長さが４ｃｍ以下を達成している。厚みが１ｍｍで空孔率が７５％を越えれば越えるほど垂れ下がりやすくなり、水平状態から垂下し始めるまでのシートの長さは４ｃｍより短くなっていくのでドレープ性が向上する。また、空孔率が７０％～７５％の範囲で厚みが１ｍｍより薄くなればなるほど垂れ下がりやすくなり、水平状態から垂下し始めるまでのシートの長さは４ｃｍより短くなっていくのでドレープ性が向上する。さらに、空孔率が９５％の場合には、厚みが１ｍｍ以上の一定の範囲において水平状態から垂下し始めるまでのシートの長さは４ｃｍ以下となる。さらにまた、厚みが０．５ｍｍの場合には、空孔率が７５％未満の一定の範囲において水平状態から垂下し始めるまでのシートの長さは４ｃｍ以下となる。 As an example of the PTFE porous sheet having the draping property, in the case of a PTFE porous sheet having a thickness of 1 mm and a porosity of 70% to 75%, the length of the sheet from the horizontal state until the drooping starts is determined. 4 cm or less is achieved. As the thickness exceeds 1% and the porosity exceeds 75%, the sheet is more likely to sag, and the length of the sheet until it starts to sag from the horizontal state becomes shorter than 4 cm, thus improving the drape. In addition, it becomes easier to sag as the thickness becomes thinner than 1 mm in the porosity range of 70% to 75%, and the drapeability is improved because the length of the sheet until it starts to sag from the horizontal state becomes shorter than 4 cm. To do. Further, when the porosity is 95%, the length of the sheet until it starts to hang down from the horizontal state within a certain range of thickness of 1 mm or more is 4 cm or less. Furthermore, when the thickness is 0.5 mm, the length of the sheet until it starts to hang down from the horizontal state in a certain range where the porosity is less than 75% is 4 cm or less.
　本発明の実施形態に係るＰＴＦＥ多孔質シートの製造方法により、肉厚・広幅・長尺のＰＴＦＥ多孔質シートが提供できる。 A thick, wide, and long PTFE porous sheet can be provided by the method for producing a porous PTFE sheet according to an embodiment of the present invention.
　次に本発明の好適な実施例を添付の図面に基づいて詳細に説明する。 Next, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
　１．金型
　本実施例におけるＰＴＦＥ多孔質シートは、その作成において次のような形状の金型によって達成される。 1. Mold The PTFE porous sheet in this example is achieved by a mold having the following shape in its production.
　図４及び図５に示すように、ペースト押出成形金型１０は、予備成形体が充填されるシリンダー１１とオリフィス１２と扇状のフラットダイ１３とから構成される。 As shown in FIGS. 4 and 5, the paste extrusion mold 10 includes a cylinder 11, an orifice 12, and a fan-shaped flat die 13 filled with a preform.
　シリンダー１１は、その断面の内面形状が１辺ａの長さ７０ｍｍの正方形をなすものである。 The cylinder 11 has a cross-sectional inner surface shape of a square with a side a of 70 mm in length.
　当該シリンダー１１の下部に連設されるオリフィス１２は、絞り角７０度であって、その絞り口が、フラットダイ１３の扇状に広がる方向の幅ｄが１５ｍｍであり、フラットダイ１３の先絞りになる方向の幅ｃが２０ｍｍであって、その絞り比が１６．３３であり、長さＬが２０ｍｍの大きさをなすものである。 The orifice 12 connected to the lower portion of the cylinder 11 has a throttle angle of 70 degrees, and the throttle opening has a width d of 15 mm in the direction in which the flat die 13 extends in a fan shape. The width c in the direction is 20 mm, the aperture ratio is 16.33, and the length L is 20 mm.
　前記オリフィスの絞り口の先端には、角度８０度の扇状に広がるフラットダイ１３が連設されている。前記フラットダイ１３は、扇状に広がる１対の平板と、当該１対の平板の両側端部を連結する側板とにより囲まれた中空扇形形状をなす。詳細には、該中空扇形形状の基部から扇状の円弧側先端のフラットダイ開口部に向かって１対の平板の間隔が漸次狭くなるように構成されており、そのフラットダイ開口部幅Ｂが２５０ｍｍであり、また扇状に広がるに従って漸次狭くなるフラットダイ開口部先端の隙間Ｔが２．２ｍｍであり、フラットダイ開口部の開口面積はオリフィス絞り口の開口面積より１８３％増大する扇状に広がる形状を有する。 A flat die 13 extending in a fan shape with an angle of 80 degrees is connected to the tip of the orifice of the orifice. The flat die 13 has a hollow sector shape surrounded by a pair of flat plates extending in a fan shape and side plates connecting both side ends of the pair of flat plates. Specifically, the distance between the pair of flat plates gradually decreases from the hollow fan-shaped base to the flat die opening at the tip of the fan-shaped arc side, and the flat die opening width B is 250 mm. Further, the gap T at the tip of the flat die opening, which gradually narrows as it expands in a fan shape, is 2.2 mm, and the opening area of the flat die opening has a fan-shaped shape that increases by 183% from the opening area of the orifice orifice. Have.
　なお、ペースト押出成形金型は前記のサイズに限られるものではなく、最終目的物である多孔質シートのサイズに応じて適宜変更してもよい。 Note that the paste extrusion mold is not limited to the above-mentioned size, and may be appropriately changed according to the size of the porous sheet as the final object.
　２．シートの成形
　ＰＴＦＥファインパウダーはＦ１０６（Ｄａｉｋｉｎ　Ｉｎｄｕｓｔｒｉｅｓ，　Ｌｔｄ．製）１ｋｇを広口ポリエチレン瓶に計量し、そこに成形助剤ＩＳＯＰＡＲ（Ｅｘｘｏｎ　Ｍｏｂｉｌ　Ｃｏｒｐｏｒａｔｉｏｎの登録商標）Ｈ２３重量部を添加し、添加後１昼夜２５℃で保温熟成した。 2. Sheet Molding PTFE fine powder weighs 1 kg of F106 (Daikin Industries, Ltd.) into a wide-mouthed polyethylene bottle, and then adds 23 parts by weight of molding aid ISOPAR (registered trademark of Exxon Mobile Corporation) for 1 day and night. Aged by incubation at 25 ° C.
　予備成形体は、前記の保温熟成したパウダー１ｋｇ分を、断面が１辺６９ｍｍの正方形で長さ１７５ｍｍのサイズの中空角柱状の圧縮成形体にて作成した。 The pre-formed body was prepared by compressing a 1 kg portion of the above-mentioned heat-aging powder with a hollow prismatic compression-shaped body having a square cross section of 69 mm and a length of 175 mm.
　予備成形体を上記のペースト押出成形金型１０に挿入し、ラムの速度約１５ｍｍ／分で連続した押出成形シートを作成し、さらに、当該押出成形シートに含む成形助剤を乾燥炉で加熱除去して成形助剤除去シートを作成した。 The preform is inserted into the above paste extrusion mold 10 to produce a continuous extrusion sheet at a ram speed of about 15 mm / min, and the molding aid contained in the extrusion sheet is removed by heating in a drying furnace. Thus, a molding aid removing sheet was prepared.
　得られた成形助剤除去シートは、巻取時の張力により収縮した幅２１０ｍｍ、ペースト押出成形金型のフラットダイ開口部先端の隙間２．２ｍｍより膨張して増大した厚みが２．８ｍｍのシートであった。 The obtained sheet for forming auxiliary agent removal is a sheet having a width of 210 mm shrunk by the tension at the time of winding, and a thickness 2.8 mm increased by expanding from the gap 2.2 mm at the tip of the flat die opening of the paste extrusion mold. Met.
　なお、上記の予備成形体は、上記のペースト押出成形金型の形状及びサイズに対応して作成したものであるが、ペースト押出成形金型の形状及びサイズが変化すれば、それに応じて予備成形体の形状及びサイズも変化する。 The preform is prepared in accordance with the shape and size of the paste extrusion mold. However, if the shape and size of the paste extrusion mold changes, the preform is molded accordingly. Body shape and size also change.
　３．多孔質シートの加工
　比較試験のための試料として、上記の成形助剤除去シートを押出方向に長さ５０ｍｍだけ裁断し、以下の加工を行った。 3. Processing of porous sheet As a sample for a comparative test, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction, and the following processing was performed.
　図９に示す延伸試験器具を使用し、図１０に示すように、成形助剤除去シートの幅方向の一端を延伸試験器具（製造においてはピンテンター等のテンター装置を使用する）の左端に備えられた固定側クリップにナット締めにより固定し、前記固定側クリップの右方に位置する可動側クリップに成形助剤除去シートの幅方向の他端をナット締めにより固定した。固定側クリップと可動側クリップとの間隔は５ｃｍである。 9 is used, and as shown in FIG. 10, one end of the molding aid removing sheet in the width direction is provided at the left end of the stretch test instrument (a tenter device such as a pin tenter is used in manufacturing). The fixed side clip was fixed by nut tightening, and the other end in the width direction of the molding aid removing sheet was fixed to the movable side clip located to the right of the fixed side clip by nut tightening. The distance between the fixed side clip and the movable side clip is 5 cm.
　そして、図９に示すように、延伸試験器具右端の手回しハンドルを回して可動側クリップを右方にスライドさせ、固定側クリップと可動側クリップとの間隔を３０ｃｍに拡張して、図１０に示す５ｃｍ長さの成形助剤除去シートを、図１１に示すように、３０ｃｍ長さに６倍延伸した幅方向延伸シートを作成した。 Then, as shown in FIG. 9, the handwheel handle at the right end of the extension test instrument is turned to slide the movable side clip to the right, and the interval between the fixed side clip and the movable side clip is expanded to 30 cm, as shown in FIG. As shown in FIG. 11, a 5 cm long forming auxiliary agent removing sheet was prepared by stretching the width direction stretched sheet 6 times to a 30 cm length.
　この延伸試験器具は手動で行うものであり、熱風発生器Ｐｌａｊｅｔ（ＩＳＨＩＺＡＫＩ　ＥＬＥＣＲＴＲＩＣ　ＭＦＧ．　ＣＯ．，　Ｌｔｄ．の商標）を用いて加熱しながら６倍の延伸を行った。 This stretching test instrument was manually performed and stretched 6 times while heating using a hot air generator Plajet (trademark of ISHIZAKI ELECTRIC MFG. CO., Ltd.).
　手動での延伸速度としては、５ｃｍを３０ｃｍに延伸する時間を２分間とした。延伸速度比率は５００％÷１２０秒＝４．１７％／秒であった。 As the manual stretching speed, the time for stretching 5 cm to 30 cm was 2 minutes. The stretching speed ratio was 500% ÷ 120 seconds = 4.17% / second.
　延伸時のＰＴＦＥの温度はレーザー光温度計ＡＤ－５６１１Ａ（Ａ＆Ｄ　Ｃｏｍｐａｎｙ，Ｌｉｍｉｔｅｄ社製）で測定した。温度範囲は１００℃～１５０℃であった。 The temperature of PTFE at the time of stretching was measured with a laser thermometer AD-5611A (A & D Company, Limited). The temperature range was 100 ° C to 150 ° C.
　なお、次の熱処理工程前であれば、幅方向に延伸後、押出方向への延伸が可能であった。 In addition, before the next heat treatment step, it was possible to stretch in the extrusion direction after stretching in the width direction.
　次に上記幅方向延伸シートをクリップで挟み、３７０℃の加熱炉で３０分間熱固定処理を行い、実施例１に係る肉厚の多孔質シートを作成した。このように押出成形シートを乾燥した後にシートの幅方向に均一に延伸して、空孔率７８％の肉厚のＰＴＦＥ多孔質シートが得られた。このＰＴＦＥ多孔質シートは圧延ロールの圧延作用を受けることなく連続した幅広で肉厚のシートである。 Next, the widthwise stretched sheet was sandwiched between clips, and heat setting was performed for 30 minutes in a heating furnace at 370 ° C. to prepare a thick porous sheet according to Example 1. In this way, the extruded sheet was dried and then uniformly stretched in the width direction of the sheet to obtain a thick PTFE porous sheet having a porosity of 78%. This PTFE porous sheet is a continuous wide and thick sheet without being subjected to the rolling action of a rolling roll.
　シートを幅方向に均一に延伸できる理由は、このペースト押出成形金型内において、絞り比１６．３３のオリフィスによりＰＴＦＥのペーストの流動が押出方向になるが、その先のフラットダイにおいてペーストが扇状に広がる過程でペーストの流動が押出方向から幅方向に変化するため、ＰＴＦＥの粒子配向が押出方向と直交する幅方向に変化したことによる。 The reason why the sheet can be uniformly stretched in the width direction is that the PTFE paste flows in the extrusion direction by an orifice having a drawing ratio of 16.33 in this paste extrusion mold, but the paste is fan-shaped in the flat die ahead of it. This is because the flow of the paste changes from the extrusion direction to the width direction in the process of spreading to the width direction, so that the particle orientation of PTFE changes in the width direction orthogonal to the extrusion direction.
　実施例１と同様に成形した成形助剤乾燥除去前の押出成形シートを、押出方向と同じ方向に圧延ロールで厚み１．５ｍｍ（元の厚みの６８％）の連続した圧延シートに加工した後、実施例１と同様に成形助剤を除去した。 After processing the extruded sheet before drying and removing the molding aid formed in the same manner as in Example 1 into a continuous rolled sheet having a thickness of 1.5 mm (68% of the original thickness) with a rolling roll in the same direction as the extrusion direction. The molding aid was removed as in Example 1.
　この成形助剤除去圧延シートから実施例１と同様に比較試験のための試料として、上記の成形助剤除去シートを押出方向に長さ５０ｍｍだけ裁断し、実施例１と同様に幅方向に延伸して幅方向延伸シートを作成し、熱固定処理を行うことにより、空孔率７９％の肉厚の多孔質シートを得た。 As a sample for a comparative test as in Example 1, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction from the rolled sheet of this auxiliary forming agent, and stretched in the width direction as in Example 1. Then, a stretched sheet in the width direction was prepared, and heat setting was performed to obtain a thick porous sheet having a porosity of 79%.
　実施例１と同様に成形した成形助剤乾燥除去前の押出成形シートを、押出方向と同じ方向に圧延ロールで厚み１．２ｍｍ（元の厚みの５５％）の連続した圧延シートに加工した後、実施例１と同様に成形助剤を除去した。 After processing the extrusion-molded sheet before drying and removing the molding aid formed in the same manner as in Example 1 into a continuous rolled sheet having a thickness of 1.2 mm (55% of the original thickness) with a rolling roll in the same direction as the extrusion direction. The molding aid was removed as in Example 1.
　この成形助剤除去圧延シートから実施例１と同様に比較試験のための試料として、上記の成形助剤除去シートを押出方向に長さ５０ｍｍだけ裁断し、実施例１と同様に幅方向に延伸して幅方向延伸シートを作成し、熱固定処理を行って、空孔率７５％の肉厚の多孔質シートを得た。 As a sample for a comparative test as in Example 1, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction from the rolled sheet of this auxiliary forming agent, and stretched in the width direction as in Example 1. Then, a width direction stretched sheet was prepared, and heat setting was performed to obtain a thick porous sheet having a porosity of 75%.
　本実施例は、実施例１において使用したペースト押出成形金型より一回り小さいダイスを使用したペースト押出成形金型、すなわち、シリンダーは、その断面の内面形状が１辺ａの長さ５０ｍｍの正方形をなし、当該シリンダーの下部に連設されるオリフィスは、絞り角６０度であって、その絞り口が、扇形に広がる方向の幅ｄが１０ｍｍであり、先絞りになる方向の幅ｃが２０ｍｍであって、その絞り比が１２．５０であり、長さＬが２０ｍｍの大きさをなし、前記オリフィスの絞り口の先端には、角度７０度の扇状に広がるフラットダイが連設されている。 This example is a paste extrusion mold using a die that is slightly smaller than the paste extrusion mold used in Example 1, that is, the cylinder is a square with an inner surface shape of a cross section of a side a of 50 mm in length. The orifice continuously provided at the lower portion of the cylinder has a throttle angle of 60 degrees, the throttle opening has a width d of 10 mm in a fan-shaped direction, and a width c of 20 mm in the direction of the first throttle. The aperture ratio is 12.50, the length L is 20 mm, and a flat die extending in a fan shape with an angle of 70 degrees is connected to the tip of the orifice aperture. .
　前記フラットダイは、扇状に広がる１対の平板と、当該１対の平板の両側端部を連結する側板とにより囲まれた中空扇形形状をなす。詳細には、該中空扇形形状の基部から扇状の円弧側先端のフラットダイ開口部に向かって１対の平板の間隔が漸次狭くなるように構成されており、そのフラットダイ開口部幅Ｂが１５０ｍｍであり、また扇状に広がるに従い漸次狭くなるフラットダイ開口部先端の隙間Ｔが２ｍｍであり、フラットダイ開口部の開口面積はオリフィス絞り口の開口面積より１５０％増大する扇状に広がる形状を有する。 The flat die has a hollow sector shape surrounded by a pair of flat plates extending in a fan shape and side plates connecting both side ends of the pair of flat plates. Specifically, the distance between the pair of flat plates gradually decreases from the hollow fan-shaped base to the flat die opening at the tip of the fan-shaped arc side, and the flat die opening width B is 150 mm. Further, the gap T at the tip of the flat die opening that gradually narrows as it expands in a fan shape is 2 mm, and the opening area of the flat die opening has a shape that expands in a fan shape that is 150% larger than the opening area of the orifice aperture.
　このサイズの異なったペースト押出成形金型を用いて実施例１と同様の手順にて押出成形シートを作成し、成形助剤乾燥除去前に押出成形シートを押出方向と同じ方向に圧延ロールで厚み１ｍｍ（元の厚みの５０％）の連続した圧延シートに加工した後、実施例１と同様に成形助剤を除去した。 Using the paste extrusion molds of different sizes, an extrusion sheet was prepared in the same procedure as in Example 1, and the extrusion sheet was thickened with a rolling roll in the same direction as the extrusion direction before drying and removing the molding aid. After processing into a 1 mm (50% of the original thickness) continuous rolled sheet, the molding aid was removed as in Example 1.
　この成形助剤除去圧延シートから実施例１と同様に比較試験のための試料として、上記の成形助剤除去シートを押出方向に長さ５０ｍｍだけ裁断し、実施例１と同様に幅方向に延伸して幅方向延伸シートを作成し、さらに熱固定処理を行い、空孔率７３％の肉厚のＰＴＦＥ多孔質シートを得た。 As a sample for a comparative test as in Example 1, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction from the rolled sheet of this auxiliary forming agent, and stretched in the width direction as in Example 1. Thus, a width direction stretched sheet was prepared, and heat setting was further performed to obtain a thick PTFE porous sheet having a porosity of 73%.
　なお、圧延シートに加工する前の成形助剤除去シートは、幅１４６ｍｍ、厚み２．４ｍｍであった。 The forming aid removing sheet before being processed into a rolled sheet had a width of 146 mm and a thickness of 2.4 mm.
　実施例４においては、押出成形シートをカレンダーロールによって、それぞれ上記の厚みまで圧延した。その後、実施例１と同様に成形助剤を除去し、成形助剤が乾燥除去された成形助剤除去圧延シートをそれぞれ幅方向に延伸し、その後、押出方向に延伸したところ、厚みがあり、長尺で広幅のＰＴＦＥ多孔質シートが得られた。 In Example 4, each extruded sheet was rolled to the above thickness by a calender roll. Thereafter, the molding aid was removed in the same manner as in Example 1, and the molding aid-removed rolling sheet from which the molding aid had been removed by drying was stretched in the width direction, and then stretched in the extrusion direction. A long and wide PTFE porous sheet was obtained.
比較例１Comparative Example 1
　実施例１と同様に成形した成形助剤乾燥除去前の押出成形シートを、押出方向と同じ方向に圧延ロールで厚み０．５ｍｍの連続した圧延シートに加工した後、実施例１と同様に成形助剤を除去した。 The extrusion molded sheet before drying removal of the molding aid formed in the same manner as in Example 1 was processed into a continuous rolled sheet having a thickness of 0.5 mm with a rolling roll in the same direction as the extrusion direction, and then molded in the same manner as in Example 1. The auxiliary was removed.
　この成形助剤除去圧延シートから実施例１と同様に比較試験のための試料として、上記の成形助剤除去シートを押出方向に長さ５０ｍｍだけ裁断し、実施例１と同様に幅方向に延伸したが、延伸しない部分と局部的に延伸作用を受ける部分とによりネッキングが発生し、均一な延伸ができなかった。 As a sample for a comparative test as in Example 1, the above-mentioned forming auxiliary agent removal sheet was cut by a length of 50 mm in the extrusion direction from the rolled sheet of this auxiliary forming agent, and stretched in the width direction as in Example 1. However, necking occurred due to the part that did not stretch and the part that was locally stretched, and uniform stretching was not possible.
　比較例１の場合は、シートの厚みが元の厚みの２３％まで圧延された結果、幅方向の不均一延伸が発生した。このようなことが起こるのは、実施例１と同様に作成し、幅方向に粒子を整列させた押出成形シートを過度に圧延した結果、幅方向に整列している粒子の配列方向が崩れたことによるものと思われる。 In the case of Comparative Example 1, as a result of rolling the sheet to 23% of the original thickness, non-uniform stretching in the width direction occurred. Such a phenomenon occurs in the same manner as in Example 1. As a result of excessively rolling an extruded sheet in which particles are aligned in the width direction, the arrangement direction of the particles aligned in the width direction is broken. It seems to be due to this.
比較例２Comparative Example 2
　実施例４と同様のペースト押出成形金型で成形した成形助剤乾燥除去前の押出成形シートを押出方向と同じ方向に圧延ロールで厚み０．１３ｍｍ（元の厚みの６．５％）の連続した圧延シートに加工した後、実施例１と同様に成形助剤を除去した。この成形助剤除去圧延シートから実施例１と同様に成形助剤を除去した。 Continuously having a thickness of 0.13 mm (6.5% of the original thickness) with a rolling roll in the same direction as the extrusion direction of the extruded sheet before drying removal of the molding aid molded with the same paste extrusion mold as in Example 4. After processing into the rolled sheet, the molding aid was removed in the same manner as in Example 1. In the same manner as in Example 1, the forming aid was removed from the forming aid-removed rolled sheet.
　この成形助剤除去圧延シートから実施例１と同様に比較試験のための試料として、上記の成形助剤除去シートを押出方向に長さ５０ｍｍだけ裁断し、その両端を保持して幅方向に延伸したが、局所のみに延伸作用が加わってネッキングが発生し、均一に延伸ができなかった。 As a sample for a comparative test in the same manner as in Example 1 from the rolled sheet for removing the forming auxiliary agent, the above forming auxiliary agent removing sheet is cut by a length of 50 mm in the extrusion direction, and both ends thereof are held and stretched in the width direction. However, the stretching action was applied only to the local area, necking occurred, and uniform stretching could not be achieved.
比較例３Comparative Example 3
　実施例１の金型のシリンダーの形状及びサイズ、フラットダイの形状及び開口部のサイズは同一で、オリフィスの絞り口を小さくして絞り比を４８．５５とした結果、面積増大率が５４５％となり、押出成形時に蛇行しながらシートが押し出されたため、正常な押出成形シートは得られず延伸機に設置することができなかった。 The shape and size of the cylinder of the mold of Example 1, the shape of the flat die, and the size of the opening are the same, and as a result of reducing the orifice opening to 48.55, the area increase rate is 545%. Thus, since the sheet was extruded while meandering during extrusion, a normal extruded sheet could not be obtained and could not be installed in a stretching machine.
　上記の実施例１～実施例４及び比較例１～比較例３により得られた各シートの性能結果を下記表１に表す。
The performance results of the sheets obtained in Examples 1 to 4 and Comparative Examples 1 to 3 are shown in Table 1 below.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　次にドレープ性についての実験を行った。 Next, an experiment on drape was performed.
　図１２に示すように、実施例３により作成した厚みが約１ｍｍで空孔率約７５％のＰＴＦＥ多孔質シートと、厚みが約１ｍｍで空孔率約７６％のＰＯＬＹＦＬＯＮペーパーとのドレープ性を比較した。図１２の写真の手前側に写っているのが実施例３のＰＴＦＥ多孔質シートであり、図１２の写真の奥に写っているのがＰＯＬＹＦＬＯＮペーパーである。当該写真から明らかなように、実施例３により作成したＰＴＦＥ多孔質シートのドレープ性がＰＯＬＹＦＬＯＮペーパーのドレープ性より高いことがわかる。実施例３により作成したＰＴＦＥ多孔質シートが垂下し始めるのが３ｃｍであるのに対し、ＰＯＬＹＦＬＯＮペーパーが垂下し始めるのが１０ｃｍであった。 As shown in FIG. 12, the draping property of the PTFE porous sheet having a thickness of about 1 mm and a porosity of about 75% and the POLYFLON paper having a thickness of about 1 mm and a porosity of about 76%, as prepared in Example 3, was obtained. Compared. The PTFE porous sheet of Example 3 is shown on the near side of the photograph of FIG. 12, and the POLYFLON paper is reflected on the back of the photograph of FIG. As is clear from the photograph, it can be seen that the drapeability of the PTFE porous sheet prepared in Example 3 is higher than that of POLYFLON paper. The PTFE porous sheet prepared in Example 3 started to sag 3 cm, whereas the POLYFLON paper started to sag 10 cm.
　また、図１３に示すように、実施例３により作成した厚みが約１ｍｍで空孔率約７５％のＰＴＦＥ多孔質シートと、厚みが約１ｍｍで空孔率７１％のＨＹＰＥＲ－ＳＨＥＥＴとのドレープ性を比較した。図１３の写真の手前側に写っているのが実施例３のＰＴＦＥ多孔質シートであり、写真の奥に写っているのがＨＹＰＥＲ－ＳＨＥＥＴである。当該写真から明らかなように、実施例３により作成したＰＴＦＥ多孔質シートのドレープ性がＨＹＰＥＲ－ＳＨＥＥＴのドレープ性より高いことがわかる。実施例３により作成したＰＴＦＥ多孔質シートが垂下し始めるのが３ｃｍであるのに対し、ＨＹＰＥＲ－ＳＨＥＥＴが垂下し始めるのが１５ｃｍであった。 Further, as shown in FIG. 13, a drape of a PTFE porous sheet having a thickness of about 1 mm and a porosity of about 75%, and a HYPER-SHEET having a thickness of about 1 mm and a porosity of 71%, as prepared in Example 3. Sex was compared. The PTFE porous sheet of Example 3 is shown in the front side of the photograph in FIG. 13, and HYPER-SHEET is in the back of the photograph. As is apparent from the photograph, it can be seen that the drapeability of the PTFE porous sheet prepared in Example 3 is higher than that of HYPER-SHEEET. The PTFE porous sheet prepared in Example 3 started to sag 3 cm, whereas HYPER-SHEET started to sag 15 cm.
　以上、本発明の実施形態を説明したが、この実施形態は、例として提示したものであり、発明の範囲を限定することは意図していない。この実施形態は、その他の様々な形態で実施されることが可能であり、発明の要旨を逸脱しない範囲で、種々の省略、置き換え、変更を行うことができる。この実施形態やその変形は、発明の範囲や要旨に含まれると同様に、特許請求の範囲に記載された発明とその均等の範囲に含まれるものである。 As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. This embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the spirit of the invention. This embodiment and its modifications are included in the scope of the present invention and the gist thereof, and are also included in the invention described in the claims and the equivalent scope thereof.
　本発明の製造方法により製造されたＰＴＦＥ多孔質シートは、例えば骨折などの際にギプス包帯で固定するときに皮膚と接触する側のインナー材として使用できる。また、半導体製造工程に使用されるリン酸類の液体を流す管や継ぎ目あるいはバルブ廻りの断熱保温材等のような形状が複雑に変化する要所に使用することができる。さらに、物品の包装材として使用することができる。その他、緩衝材、電子機器のシール材、液晶基板の設置部材、絶縁材など広範囲に使用できる。 The PTFE porous sheet produced by the production method of the present invention can be used as an inner material that comes into contact with the skin when it is fixed with a cast bandage, for example, in the case of a fracture. Moreover, it can be used for the point where the shape changes in a complicated manner, such as a pipe for flowing a liquid of phosphoric acid used in a semiconductor manufacturing process, a joint or a heat insulating heat insulating material around a valve. Furthermore, it can be used as a packaging material for articles. In addition, it can be used in a wide range such as cushioning materials, electronic device sealing materials, liquid crystal substrate installation members, and insulating materials.
１０…ペースト押出成形金型
１１…シリンダー
１２…オリフィス
１３…フラットダイ
ａ…シリンダーの断面の内面形状の１辺
ｃ…オリフィス絞り口における先絞りになる方向の幅
ｄ…オリフィス絞り口における扇形に広がる方向の幅
Ｌ…オリフィス絞り口の長さ
Ｂ…ダイス開口部の幅
Ｔ…ダイス開口部の隙間 DESCRIPTION OF SYMBOLS 10 ... Paste extrusion mold 11 ... Cylinder 12 ... Orifice 13 ... Flat die a ... One side c of internal shape of the cross section of a cylinder c ... Width in the direction which becomes a front drawing in an orifice restrictor Directional width L ... Orifice throttle opening length B ... Die opening width T ... Die opening gap

Claims (2)

  1. 　成形助剤を添加したポリテトラフルオロエチレンパウダーにより予備成形体を作成し、
    　前記予備成形体をペースト押出成形金型内に投入し、当該成形金型内の予備成形体を押し出すラムによって、当該成形金型内の予備成形体を連続的に押し出すことにより押出方向に長尺の押出成形シートを作成し、
    　前記押出成形シートから前記成形助剤を除去することにより成形助剤除去シートを作成し、
    　テンター装置に前記成形助剤除去シートの幅方向両端を固定し、ポリテトラフルオロエチレンの室温転移温度以上の環境下で当該成形助剤除去シートを幅方向にのみ元の幅の１．２倍～２５倍に延伸することにより幅方向延伸シートを作成し、
    　前記幅方向延伸シートをポリテトラフルオロエチレンの融点付近の温度で熱固定処理することにより製造されるポリテトラフルオロエチレン多孔質シートであり、
    　前記成形金型は、連設されたシリンダー、オリフィス及びフラットダイを備え、
    　前記シリンダーは中空筒状であり、当該シリンダーに連設されている前記オリフィスは中空矩形状であって、当該シリンダー中空部の断面積に対する当該オリフィス中空部の断面積の比が１０：１～３０：１の絞り比であり、
    　前記オリフィス中空部の矩形状断面は長辺の長さが短辺の長さの１～３倍の矩形であり、
    　前記オリフィスの出口である絞り口に連設されている前記フラットダイは、当該オリフィスの絞り口側を基部として扇状に広がる２つの平面と、当該２つの平面の両側端部を連結する側面とにより囲まれ、扇状の円弧側先端に細幅のフラットダイ開口部が形成された中空扇状をなし、当該２つの平面の扇状の基部から円弧側先端に向かって当該２つの平面の間隔が狭くなるように構成されており、
    　前記フラットダイ開口部の開口面積は、前記オリフィスの絞り口の開口面積の１２５％～３００％であり、当該フラットダイ開口部における両側面間の内法長さは１００ｍｍ～５００ｍｍであり、前記２つの平面間の内法長さは１ｍｍ～５ｍｍである
    　ことを特徴とするポリテトラフルオロエチレン多孔質シートの製造方法。     Create a preform with polytetrafluoroethylene powder to which a molding aid is added,
    The preform is put into a paste extrusion molding die, and the preform in the molding die is continuously extruded by a ram for extruding the preform in the molding die. Create an extruded sheet of
    Create a molding aid removal sheet by removing the molding aid from the extruded sheet,
    Both ends of the molding aid removal sheet in the width direction are fixed to a tenter device, and the molding aid removal sheet is 1.2 times the original width or more in the width direction only in an environment at or above the room temperature transition temperature of polytetrafluoroethylene. Create a width direction stretched sheet by stretching 25 times,
    A polytetrafluoroethylene porous sheet produced by heat-setting the width-oriented stretched sheet at a temperature near the melting point of polytetrafluoroethylene;
    The molding die includes a cylinder, an orifice, and a flat die that are continuously provided,
    The cylinder has a hollow cylindrical shape, the orifice connected to the cylinder has a hollow rectangular shape, and the ratio of the cross-sectional area of the orifice hollow portion to the cross-sectional area of the cylinder hollow portion is 10: 1 to 30. : 1 aperture ratio,
    The rectangular cross section of the orifice hollow part is a rectangle whose long side is 1 to 3 times the length of the short side,
    The flat die continuously connected to the orifice that is the outlet of the orifice has two planes that expand in a fan shape with the orifice side of the orifice as a base, and side surfaces that connect both side ends of the two planes. It is surrounded and has a hollow fan shape in which a narrow flat die opening is formed at the fan-shaped arc side tip, so that the distance between the two planes becomes narrower from the fan-shaped base of the two planes toward the arc-side tip. Is composed of
    The opening area of the flat die opening is 125% to 300% of the opening area of the orifice of the orifice, and the inner length between both side surfaces of the flat die opening is 100 mm to 500 mm. A method for producing a polytetrafluoroethylene porous sheet, wherein an internal length between two planes is 1 mm to 5 mm.
  2. 　成形助剤を添加したポリテトラフルオロエチレンパウダーにより予備成形体を作成し、
    　前記予備成形体をペースト押出成形金型内に投入し、当該成形金型内の予備成形体を押し出すラムによって、当該成形金型内の予備成形体を連続的に押し出すことにより押出方向に長尺の押出成形シートを作成し、
    　前記押出成形シートを圧延ロールにより圧延し、厚みが０．５ｍｍ以上で元の厚みの３５％以上の厚みの圧延シートを作成し、
    　前記圧延シートから成形助剤を除去することにより成形助剤除去圧延シートを作成し、
    　テンター装置に前記成形助剤除去圧延シートの幅方向両端を固定し、ポリテトラフルオロエチレンの室温転移温度以上の環境下で当該成形助剤除去圧延シートを幅方向にのみ元の幅の１．２倍～２５倍に延伸することにより幅方向延伸圧延シートを作成し、
    　前記幅方向延伸圧延シートをポリテトラフルオロエチレンの融点付近の温度で熱固定処理することにより製造されるポリテトラフルオロエチレン多孔質シートであり、
    　前記成形金型は、連設されたシリンダー、オリフィス及びフラットダイを備え、
    　前記シリンダーは中空筒状であり、当該シリンダーに連設されている前記オリフィスは中空矩形状であって、当該シリンダー中空部の断面積に対する当該オリフィス中空部の断面積の比が１０：１～３０：１の絞り比であり、
    　前記オリフィス中空部の矩形状断面は長辺の長さが短辺の長さの１～３倍の矩形であり、
    　前記オリフィスの出口である絞り口に連設されている前記フラットダイは、当該オリフィスの絞り口側を基部として扇状に広がる２つの平面と、当該２つの平面の両側端部を連結する側面とにより囲まれ、扇状の円弧側先端に細幅のフラットダイ開口部が形成された中空扇状をなし、当該２つの平面の扇状の基部から円弧側先端に向かって当該２つの平面の間隔が狭くなるように構成されており、
    　前記フラットダイ開口部の開口面積は、前記オリフィスの絞り口の開口面積の１２５％～３００％であり、当該フラットダイ開口部における両側面間の内法長さは１００ｍｍ～５００ｍｍであり、前記２つの平面間の内法長さは１ｍｍ～５ｍｍである
    　ことを特徴とするポリテトラフルオロエチレン多孔質シートの製造方法。     Create a preform with polytetrafluoroethylene powder to which a molding aid is added,
    The preform is put into a paste extrusion molding die, and the preform in the molding die is continuously extruded by a ram for extruding the preform in the molding die. Create an extruded sheet of
    The extruded sheet is rolled with a rolling roll to create a rolled sheet having a thickness of 0.5 mm or more and a thickness of 35% or more of the original thickness,
    Create a forming aid removal rolling sheet by removing the forming aid from the rolled sheet,
    Both ends in the width direction of the forming auxiliary agent-removed rolled sheet are fixed to a tenter device, and the forming auxiliary agent-removed rolled sheet is 1.2% of the original width only in the width direction in an environment at or above the room temperature transition temperature of polytetrafluoroethylene. Create a rolled sheet in the width direction by stretching to 25 to 25 times,
    A polytetrafluoroethylene porous sheet produced by heat-setting the width-oriented stretched sheet at a temperature near the melting point of polytetrafluoroethylene;
    The molding die includes a cylinder, an orifice, and a flat die that are continuously provided,
    The cylinder has a hollow cylindrical shape, the orifice connected to the cylinder has a hollow rectangular shape, and the ratio of the cross-sectional area of the orifice hollow portion to the cross-sectional area of the cylinder hollow portion is 10: 1 to 30. : 1 aperture ratio,
    The rectangular cross section of the orifice hollow part is a rectangle whose long side is 1 to 3 times the length of the short side,
    The flat die continuously connected to the orifice that is the outlet of the orifice has two planes that expand in a fan shape with the orifice side of the orifice as a base, and side surfaces that connect both side ends of the two planes. It is surrounded and has a hollow fan shape in which a narrow flat die opening is formed at the fan-shaped arc side tip, so that the distance between the two planes becomes narrower from the fan-shaped base of the two planes toward the arc-side tip. Is composed of
    The opening area of the flat die opening is 125% to 300% of the opening area of the orifice of the orifice, and the inner length between both side surfaces of the flat die opening is 100 mm to 500 mm. A method for producing a polytetrafluoroethylene porous sheet, wherein an internal length between two planes is 1 mm to 5 mm.
PCT/JP2016/000725 2015-02-24 2016-02-12 Method for producing porous polytetrafluoroethylene sheet WO2016136172A1 (en)

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