JP2006305762A - Manufacturing method of filler-containing polytetrafluoroethylene sheet and extrusion molding die - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of filler-containing polytetrafluoroethylene (PTFE) sheet capable of making the sheet thin even in a case that the ratio of the filler in the sheet is high. <P>SOLUTION: A mixture, which contains the filler, PTFE and a processing aid, is molded into a sheetlike molded object by extrusion molding using a die 1 while this sheetlike molded object is rolled and the processing aid is subsequently removed to manufacture the filler-containing PTFE sheet. The die 1 has a cylinder part 3, a ram 2, a first taper part 4, an orifice part 5, a second tapered part 6 and a land part 7. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a polytetrafluoroethylene (hereinafter referred to as “PTFE”) sheet containing a filler, an extrusion die that can be used for the production method, and the like.

  Conventionally, filler-containing PTFE sheets have been used for polarizable electrode sheets for electric double layer capacitors, dry sheets for organic EL displays, and the like. As a method for producing a PTFE sheet, a method of extruding a mixture of PTFE powder and a processing aid using a die has been proposed (see Patent Document 1). However, when a filler-containing PTFE sheet is produced by this method, the proportion of the filler is large. For example, when the proportion of the total amount of PTFE and the filler is 60% by volume or more, a part of the die outlet Therefore, it was difficult to obtain a sheet having a predetermined width only by obtaining a non-uniform extrudate.

  Also proposed is a method in which activated carbon and conductive carbon are used as fillers, a mixture of fluoropolymer resin and processing aid is extruded as a rod-shaped preform, and the extruded product is rolled to form a sheet. (See Patent Document 2). However, the sheet obtained by this method has insufficient strength in the width direction, and cracks and tears occur when the rolling magnification is increased. Therefore, thinning by rolling is not enough to meet demand.

  A method for forming a PTFE sheet that defines the drawing ratio of the cross-sectional area of a die used for extrusion molding has been proposed (see Patent Document 3). However, even in this method, if there are many fillers, cracking and tearing occur. It was generated and extrusion into a sheet was difficult. Even if the sheet can be extruded, it becomes a sheet with insufficient strength in the width direction, and the sheet is cracked and cracked by the rolling operation, making it difficult to reduce the thickness.

As described above, in the method for producing the filler-containing PTFE sheet, various devices have been devised, but a practical method for thinning has not been developed yet.
Japanese Patent Publication No.42-14178 JP 2001-85280 A JP 2000-235938 A

  The present invention has been made in view of such circumstances, and in the method for producing a filler-containing PTFE sheet, the object of the invention is to provide a production method capable of thinning the sheet even when the proportion of the filler is large. And Another object of the present invention is to provide an extrusion die used in this production method.

  In order to achieve the above object, the production method of the present invention includes an extrusion process in which a mixture containing a filler, PTFE and a processing aid is extruded into a sheet shape using a die, and a sheet obtained by the extrusion process. A method for producing a filler-containing PTFE sheet comprising a rolling step of rolling a shaped product and a removing step of removing the processing aid from a rolled sheet obtained by the rolling step, wherein the die in the extrusion step A cylinder portion, a ram movable within the cylinder portion, a first taper portion continuing from the cylinder portion to the outlet side, an orifice portion continuing further to the outlet side than the first taper portion, and the orifice portion Furthermore, it has a 2nd taper part which continues to an exit side, and a land part which continues further to an exit side from the said 2nd taper part, The taper angle of the said 2nd taper part is 50 degrees or less And the length of the land portion is in the range of 20 to 300 mm, and the ratio (W / T) between the outlet width W and the outlet thickness T of the land portion is 20 ≦ (W / T) <300. A die satisfying the relationship is used.

  The extrusion die according to the present invention includes a cylinder part, a ram that can move in the cylinder part, a first taper part that continues from the cylinder part to the outlet side, and an outlet side further than the first taper part. A second taper portion that continues further to the exit side than the orifice portion, and a land portion that continues further to the exit side than the second taper portion, and the taper angle of the second taper portion is It is 50 ° or less, the length of the land portion is in the range of 20 to 300 mm, and the ratio (W / T) between the outlet width W and the outlet thickness T of the land portion is 20 ≦ (W / T ) Extrusion die satisfying the relationship <300.

  According to the production method of the present invention, even when the proportion of the filler in the total amount of PTFE and the filler is large, the sheet can be extruded into a sheet shape. The strength in the width direction is also sufficiently high. Therefore, even when this sheet-like molded product is rolled, the sheet is less likely to be cracked or torn. As a result, according to the present invention, it is possible to manufacture a filler-containing PTFE sheet that is thinner than the conventional manufacturing method.

  Moreover, according to the extrusion die of the present invention, for example, a filler-containing PTFE sheet-like molded product that can be thinned by rolling can be obtained.

  In the present invention, the taper angle of the second taper portion in the die means that the second taper portion that continues further to the outlet side than the orifice portion that is the narrowest width portion in the cross section in the width direction of the die is virtually assumed on the inlet side. For example, the angle indicated by α in FIG. 4 corresponds to the angle at which the extended straight lines intersect. FIG. 4 is a part of a cross-section in the width direction of the die of the present invention, 4 is a first taper portion, 5 is an orifice portion, and 6 is a second taper portion.

  This die has a land portion having a constant cross-sectional shape of the flow path continuing further to the outlet side than the second tapered portion.

  Further, in this die, the land portion has a length in the range of 20 to 300 mm, and a ratio (W / T) between the outlet width W and the outlet thickness T is 20 ≦ (W / T). <300 relationship is satisfied. The ratio (W / T) between the outlet width W of the land portion and the outlet thickness T more preferably satisfies the relationship of 30 <(W / T) <250, and the relationship of 50 <(W / T) <250. It is further preferable to satisfy

  In the production method of the present invention, a mixture containing a filler, PTFE, and a processing aid is extruded into a sheet using a die, the sheet-like molding is rolled, and then the processing aid is removed.

  In the production method of the present invention, it is preferable to roll the sheet-like molded product so as to have a thickness of 0.1 mm or less.

  The extrusion die of the present invention is a die used to extrude a mixture containing a filler, PTFE and a processing aid. However, the die of the present invention can also be used for extrusion molding other than this mixture.

  Next, an example of the manufacturing method of the filler containing PTFE sheet of this invention is demonstrated in detail.

  In the production method of the present invention, first, a mixture containing PTFE, a filler and a processing aid is prepared.

  Examples of PTFE used as a raw material in the present invention include an aqueous dispersion in which polymer particles obtained by emulsion polymerization of tetrafluoroethylene are stabilized, and a powder (fine powder) obtained by coagulating the dispersion. It is done. The content of PTFE is, for example, in the range of 5 to 95% by mass, preferably in the range of 5 to 60% by mass, and more preferably in the range of 10 to 30% with respect to the total mass of PTFE and filler. It is the range of mass%.

  Examples of the filler include carbon fine powder, desiccant, photocatalyst particles, antibacterial particles, moisture adsorbent particles, metal powder, polymer powder, ceramic powder, glass powder, oxide powder, or short fibers thereof. Is mentioned. Examples of the fine carbon powder include fine powders such as activated carbon, carbon black, graphite, acetylene black, graphite whisker, and carbon nanotube.

  The filler may be used alone or in combination of two or more, and can be appropriately determined according to the role of the rolled sheet to be produced. For example, in producing a polarizable electrode sheet for an electric double layer capacitor, a combination of activated carbon for improving the energy density in the sheet and carbon black as a conductive material is preferable. For example, a dry sheet of an organic EL display In preparing the above, it is preferable to use zeolite, calcium oxide, or strontium oxide as the desiccant.

  The content of the filler is, for example, in the range of 5-95% by mass, preferably in the range of 40-95% by mass, and more preferably in the range of 70-95% with respect to the total mass of PTFE and the filler. The range is 90% by mass.

  The mixing method of the filler and PTFE is not particularly limited, and examples thereof include a method of mixing the PTFE fine powder and the filler in a dry state, a method of directly mixing the PTFE dispersion and the filler, and the like. In the case of increasing the proportion of the filler, it is preferable to use a dispersion in which PTFE is dispersed in the form of primary particles rather than PTFE fine powder from the viewpoint of dispersibility. As for a method of mixing such a filler and PTFE dispersion, for example, a method generally called co-coagulation disclosed in JP-A-8-253600 can be used. In this method, the PTFE dispersion is added while stirring the aqueous dispersion of the filler, and if necessary, a water-insoluble organic liquid is added as a coagulation accelerator. Examples of the water-insoluble organic liquid include hydrofluorocarbons such as methylene chloride and trichloroethylene, aliphatic hydrocarbons such as hexane and heptane, and aromatic hydrocarbons such as toluene and xylene. Stirring is continued for about several minutes, and after co-coagulation is completed, the coagulated product is filtered to obtain a water-containing mixture, which is heated at a temperature of about 80 to 150 ° C. with a hot air circulating dryer at 12 to 48 ° C. The powder is dried for a period of time to remove moisture and pulverized with a Henschel mixer or the like to obtain a mixed powder of filler and PTFE.

  A processing aid (liquid lubricant) for extrusion molding is added to the mixture. The processing aid may be added after or simultaneously with the mixing of the PTFE and the filler.

  The processing aid is not particularly limited as long as it is used for extrusion molding of PTFE. For example, kerosene, kerosene, liquid paraffin, solvent naphtha, petroleum ether, white oil, ethylene glycol, glycerin, water, alcohol Among them, kerosene, kerosene, and liquid paraffin are preferable.

  The amount of the processing aid to be added is appropriately determined, but is usually in the range of 20 to 80% by mass, preferably 40 to 60% by mass with respect to the total mass of PTFE, filler and processing aid. % Range.

The mixing time of PTFE, a filler, and a processing aid is, for example, in the range of 1 to 60 minutes, preferably in the range of 2 to 30 minutes, and more preferably in the range of 5 to 20 minutes. The mixing method is not particularly limited, and examples thereof include a method of rotating PTFE, a filler and a processing aid in a bottle, a method of mixing using a V-type blender, a tumbler and the like.

  The mixing temperature of PTFE, filler, and processing aid is preferably lower than the transition temperature of PTFE that can suppress PTFE fiberization even when shearing force is applied during mixing, and more preferably 15 ° C or less. More preferably, it is the range of -10-15 degreeC, More preferably, it is the range of 0-10 degreeC.

  Moreover, it is preferable to perform aging after mixing PTFE, a filler, and a processing aid. This is because the processing aid uniformly penetrates into PTFE and the filler by aging, and the workability is improved. The aging time is, for example, in the range of 1 to 100 hours, preferably in the range of 2 to 24 hours, and more preferably in the range of 6 to 12 hours. The aging temperature is, for example, in the range of 5 to 35 ° C., preferably in the range of 5 to 25 ° C., and more preferably in the range of 5 to 15 ° C.

  Next, prior to extruding the mixture containing PTFE, a filler and a processing aid, it is preferable to preform the mixture by, for example, filling the mixture into a cylindrical mold and compressing the mixture. By this preforming, voids in the mixture are reduced, and defects such as blistering of the sheet-like molded product that are generated when air does not escape sufficiently in extrusion molding performed by the die can be prevented.

  Since the preliminary molding is performed for the purpose of adjusting the shape for good extrusion molding, the pressure at that time does not need to be so high, and is, for example, in the range of 1 to 3 MPa, preferably 1 to 2 MPa. Range. The preforming temperature may be a temperature at which the processing aid does not volatilize much, and is, for example, in the range of 0 to 35 ° C., and preferably in the range of 10 to 25 ° C.

  In the production method of the present invention, a mixture containing PTFE, a filler and a processing aid or a preformed product of this mixture is extruded into a sheet shape by the die.

Here, the extrusion die of the present invention will be described. 1-3 show an example of the extrusion die of the present invention. 1 is a plan view of the die, FIG. 2 is a cross-sectional view taken along the line II of FIG. 1, and FIG. 3 is a cross-sectional view taken along the line II-II of FIG. As shown in the figure, the die 1 includes a cylindrical cylinder portion 3, a ram 2 that can move within the cylinder portion 3, a first tapered portion 4 that extends from the cylinder portion 3 to the outlet side, and the first portion. The first tapered portion 4 further on the outlet side, the second tapered portion 6 further on the outlet side of the orifice portion 5, and the land portion 7 further on the outlet side of the second tapered portion 6. It consists of and. As described above, the taper angle of the second taper portion 6 in this die is set to 50 ° or less. In order to perform extrusion using this die, the mixture containing PTFE, the filler and the processing aid or a preformed product of this mixture is supplied to the cylinder part 3, and then the ram 2 is pressed and the inside of the cylinder part 3 is pressed. Is lowered. As the ram 2 descends, the mixture or the preform of the mixture sequentially passes through the first taper portion 4, the orifice portion 5, the second taper portion 6 and the land portion 7, and the sheet is discharged from the land portion 7 outlet. Come out in shape.

  In the die shown in FIGS. 1 to 3, the length of the first taper portion 4 is the dimension indicated by J in FIG. 2, and the length of the second taper portion 6 is the dimension indicated by K in FIG. The exit width in the portion 7 corresponds to the dimension indicated by W in FIG. 2, and the exit thickness in the land portion 7 corresponds to the dimension indicated by T in FIG. The taper angle of the second taper portion 6 is the angle indicated by α in FIG. 4 as described above.

  The diameter of the cylindrical cylinder portion 3 is set according to various conditions, but from a practical viewpoint, it is usually in the range of 10 to 250 mm, preferably in the range of 70 to 200 mm, more preferably 90. It is in the range of ~ 150 mm. Moreover, the length (dimension of the direction orthogonal to a radial direction) is the range of 100-2000 mm, for example, Preferably, it is the range of 300-1500 mm, More preferably, it is the range of 500-1000 mm.

  As shown in FIG. 2, the first taper portion 4 is tapered so that the diameter on the orifice portion 5 side is small. The taper angle of the first taper portion 4 is not particularly limited, but is, for example, in the range of 15 ° to 120 °, preferably in the range of 15 ° to 90 °, and more preferably in the range of 25 ° to 60 °. It is in the range of °. In the present invention, the taper angle of the first taper portion in the die is an angle at which a straight line virtually extending the first taper portion located on the inlet side from the orifice portion which is the narrowest width portion on the outlet side intersects. For example, the angle indicated by β in FIG. FIG. 5 is a part of a cross-section in the width direction of the die according to the present invention, where 4 indicates a first taper portion, 5 indicates an orifice portion, and 6 indicates a second taper portion. The length of the first tapered portion 4 (the dimension indicated by J in FIG. 2) is, for example, in the range of 30 to 600 mm, preferably in the range of 35 to 550 mm, and more preferably in the range of 40 to 500 mm. It is.

  As shown in FIG. 1, the orifice portion 5 has a rectangular cross section, and the width thereof is, for example, in the range of 2 to 80 mm, preferably in the range of 3 to 70 mm, and more preferably in the range of 4 to 60 mm. For example, the thickness is in the range of 5 to 120 mm, preferably in the range of 10 to 100 mm, and more preferably in the range of 30 to 80 mm. The length of the orifice portion 5 (the dimension indicated by C in FIG. 2) is usually in the range of 5 to 50 mm, but is not limited thereto.

  As shown in FIG. 2, the second taper portion 6 is tapered so that the width on the land portion 7 side is increased. The length of the second taper portion 6 (the dimension indicated by K in FIG. 2) is, for example, in the range of 30 to 1000 mm, preferably in the range of 50 to 800 mm, and more preferably in the range of 50 to 600 mm. .

  As shown in FIGS. 1 and 3, the land portion 7 has a rectangular cross section, and the size of the land portion 7 is preferably in the range of 30 to 500 mm, for example, the exit width (the size indicated by W in FIG. 2). Is in the range of 50 to 400 mm, more preferably in the range of 50 to 350 mm, and the outlet thickness (the dimension indicated by T in FIG. 3) is, for example, in the range of 0.5 to 5 mm, preferably 0.8. It is in the range of ˜4 mm, more preferably in the range of 1 to 3 mm. The length of the land portion 7 (the dimension indicated by H in FIG. 2) is in the range of 20 to 300 mm as described above. The length of the land portion 7 is preferably in the range of 50 to 250 mm. PTFE particles bind when subjected to shear strain. Since this binding behavior requires time to stabilize, it is preferable to maintain the state after deformation. The die used in the manufacturing method of the present invention is provided with the land portion 7 having a constant cross-sectional shape of the flow path, so that the state can be maintained after the PTFE particles are deformed, and the sheet shape. It can prevent that a molded object becomes a wavy unstable shape.

  The temperature in the extrusion molding is, for example, in the range of 30 to 90 ° C., preferably 30 to 70 ° C. in order to improve the extrudability of the mixture and to promote the fiberization of the PTFE. It is a range, More preferably, it is the range of 30-50 degreeC.

  The extrusion speed of the ram 2 in the extrusion molding is, for example, in the range of 10 to 200 mm / min. By adjusting the speed, the extrusion is too fast and the strength expression of the PTFE becomes insufficient, or the extrusion is too slow and the processing aid oozes out, so that the properties of the sheet-like molded product in the first half and the second half of the extrusion. Can be prevented from changing. The extrusion speed of the ram 2 is preferably in the range of 10 to 100 mm / min, more preferably in the range of 20 to 80 mm / min.

  In the die 1, an RR (Reduction Ratio) that is a ratio of a cross-sectional area of the cylinder portion 3 and a cross-sectional area of the orifice portion 5 is, for example, in the range of 10 to 80. By setting the RR, the RR is too small, the strength in the extrusion direction of the extrudate decreases, and winding after extrusion becomes difficult, or the RR is too large and the extrusion pressure becomes high, It can prevent that load becomes large and extrusion becomes difficult. The RR is preferably in the range of 10-60, more preferably in the range of 15-50.

  In the mixture, it is preferable that the taper angle of the second taper portion 6 in the die is reduced as the proportion of PTFE decreases (as the amount of filler increases). For example, when the amount of the filler is 50 to 70% by mass, the taper angle is preferably in the range of 30 to 50 °. For example, when the amount of the filler is 70 to 90% by mass, the taper angle is tapered. The angle is preferably 30 ° or less. The lower limit value of the taper angle is not particularly limited, but is, for example, 10 ° from the standpoint of die length, ease of handling of the apparatus, and the like. Therefore, the taper angle of the second taper portion 6 is, for example, in the range of 10 to 50 ° when the amount of the filler is 50 to 70% by mass, for example, the amount of the filler is 70. In the case of -90 mass%, it is the range of 10-30 degrees, for example.

  In the die 1, as described above, the ratio (W / T) between the outlet width W of the land portion 7 and the outlet thickness T satisfies the relationship of 20 ≦ (W / T) <300. By satisfying this relationship, (W / T) is too small and thinning becomes difficult when rolling later, or (W / T) is too large and the sheet-like molded product is wavy and unstable. It becomes a state and it can prevent that extrusion becomes difficult.

  By the above operation, a sheet-like molded product having a smooth shape and strength in the width direction can be obtained. In the sheet-like molded product, the thickness is, for example, in the range of 0.7 to 6 mm, preferably in the range of 1 to 6 mm, and more preferably in the range of 1.2 to 6 mm.

  As described above, the production method of the present invention further includes a rolling step, and rolls the sheet-like molded product extruded into a sheet shape. The rolling step can be performed by, for example, roll rolling, intermittent press, double belt press, roll press or the like. Among these, the roll press is preferable because a uniform rolled sheet can be obtained in the extrusion direction.

  In the rolling process, since a high compression ratio is applied to the sheet-like molded product, the binding and fiberization of PTFE particles are promoted, and the strength in the extrusion direction (MD) is further improved. It is preferable to adjust to the thickness. Specifically, the number of rolling is preferably 10 times or less, and more preferably 1 to 8 times.

  The temperature of the said rolling process is the range of 30-200 degreeC, for example, Preferably, it is the range of 40-100 degreeC, More preferably, it is the range of 50-80 degreeC.

  In the filler-containing PTFE rolled sheet subjected to the rolling step, as described above, the thickness is preferably 0.1 mm or less, for example, in the range of 0.02 to 0.3 mm, preferably It is the range of 0.02-0.1 mm, More preferably, it is the range of 0.02-0.08 mm. From the filler-containing PTFE rolled sheet containing the processing aid thus obtained, the processing aid is removed by a method such as heating or extraction.

  Next, examples of the present invention will be described together with comparative examples.

To 450 g of pure water kept at a temperature of 15 ° C., zeolite powder as a filler (manufactured by Korea Cosmo Industrial Co. Ltd, trade name Colite P, average particle diameter of about 3 μm, true specific gravity of 1.5 g / cm ³ , 25 ° C., relative 500 g (with a mass of zeolite of 400 g and a capacity of 267 cm ³ ) (with a humidity of 60% and holding 20% by mass of water with respect to the total mass) was added, and the mixture was stirred at a low speed of about 10 rpm with a propeller stirring blade. Similarly, PTFE dispersion (made by Daikin Industries, trade name Polyflon PTFE D-3E, true specific gravity 2.15 g / cm ³ ) 500 g (60% by mass as a solid content, that is, 300 g in mass) kept at a temperature of 15 ° C. A volume of 139.5 cm ³ ) was gradually added. After the addition, stirring was continued for 5 minutes, and then the aggregate was filtered under reduced pressure using a Buchner funnel and filter paper. The filtrate was clear. Subsequently, this was dried at a temperature of 120 ° C. for 12 hours using a hot air circulation dryer to remove moisture. Since the obtained mixture was a mass of several centimeters, it was cooled with liquid nitrogen and pulverized by hand up to several millimeters. In addition, the ratio of the zeolite in the mixture of the obtained zeolite and PTFE is 66 volume% (57 mass% in mass).

  Next, the mixture was dried at 120 ° C. for 5 hours to remove moisture, and then 150 g of kerosene as a processing aid was added to 500 g of the mixture, and gently mixed with a spatula at 15 ° C. The mixture was aged at 20 ° C. for 48 hours in a sealed container, mixed again with a tumbler, charged into a cylindrical container, and pressurized at a temperature of 20 ° C. and a pressure of 1.5 MPa to obtain a preform.

  This preform was extruded into a sheet using a die having the shape shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 77 mm and a length of 500 mm, the first taper portion 4 has a length of 110 mm, a taper angle of 30 °, the orifice portion 5 has a width of 8 mm, and a thickness. 32 mm in length, 10 mm in length, the second taper portion 6 has a length of 67 mm, a taper angle of 35 °, and the land portion 7 has a length of 20 mm, an outlet width of 50 mm, an outlet thickness of 2.5 mm, and the aforementioned (W / T) Was 20. The RR in the die 1 is 18. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 30 mm / min. The thickness of the obtained sheet-like molded product was 5.5 mm, and the width was 44 mm.

  Next, this sheet-like molded product was gradually rolled by passing between two metal rolls heated to 60 ° C. eight times. The filler-containing PTFE rolled sheet containing the processing aid thus obtained was heated for 5 minutes with a hot air circulating drier kept at a temperature of 120 ° C. to remove kerosene. The thickness of the obtained filler-containing PTFE sheet was 0.1 mm.

  A preform formed in the same manner as in Example 1 was extruded into a sheet shape using a die having the shape shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 106 mm, a length of 800 mm, the first taper portion 4 has a length of 167 mm, a taper angle of 30 °, and the orifice portion 5 has a width of 7.8 mm. , Thickness 28.3 mm, length 10 mm, second taper portion 6 has a length of 327 mm, taper angle 20 °, land portion 7 has a length of 100 mm, outlet width 123 mm, outlet thickness 1.8 mm, W / T) was set to 68. The RR in the die 1 is 40. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 60 mm / min. The thickness of the obtained sheet-like molded product was 2.1 mm, and the width was 115 mm.

  Next, this sheet-like molded product was gradually rolled by passing between two metal rolls heated to 60 ° C. six times. The filler-containing PTFE rolled sheet containing the processing aid thus obtained was heated for 5 minutes with a hot air circulating drier kept at a temperature of 120 ° C. to remove kerosene. The thickness of the obtained filler-containing PTFE sheet was 0.1 mm.

  A preform formed in the same manner as in Example 1 was extruded into a sheet shape using a die having the shape shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 106 mm, a length of 800 mm, the first taper portion 4 has a length of 167 mm, a taper angle of 30 °, and the orifice portion 5 has a width of 7.8 mm. The second taper portion 6 has a length of 327 mm, the taper angle of 20 °, the land portion 7 has a length of 200 mm, an outlet width of 123 mm, an outlet thickness of 1.8 mm, W / T) was set to 68. The RR in the die 1 is 40. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 60 mm / min. The thickness of the obtained sheet-like molded product was 2.1 mm, and the width was 115 mm.

  Next, this sheet-like molded product was gradually rolled by passing between two metal rolls heated to 60 ° C. six times. The filler-containing PTFE rolled sheet containing the processing aid thus obtained was heated for 5 minutes with a hot air circulating drier kept at a temperature of 120 ° C. to remove kerosene. The thickness of the obtained filler-containing PTFE sheet was 0.1 mm.

  A preform formed in the same manner as in Example 1 was extruded into a sheet shape using a die having the shape shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 106 mm, a length of 800 mm, the first taper portion 4 has a length of 167 mm, a taper angle of 30 °, and the orifice portion 5 has a width of 7.8 mm. The second taper portion 6 has a length of 139 mm, the taper angle of 45 °, the land portion 7 has a length of 100 mm, an outlet width of 123 mm, an outlet thickness of 1.8 mm, W / T) was set to 68. The RR in the die 1 is 40. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 60 mm / min. The thickness of the obtained sheet-like molded product was 2.1 mm, and the width was 115 mm.

  Next, this sheet-like molded product was gradually rolled by passing between two metal rolls heated to 60 ° C. six times. The filler-containing PTFE rolled sheet containing the processing aid thus obtained was heated for 5 minutes with a hot air circulating drier kept at a temperature of 120 ° C. to remove kerosene. The thickness of the obtained filler-containing PTFE sheet was 0.1 mm.

  A preform formed in the same manner as in Example 1 was extruded into a sheet shape using a die having the shape shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 106 mm, a length of 800 mm, the first taper portion 4 has a length of 167 mm, a taper angle of 30 °, and the orifice portion 5 has a width of 8.5 mm. , Thickness 28.3 mm, length 10 mm, second taper portion 6 has a length of 432 mm, taper angle 30 °, land portion 7 has a length of 100 mm, outlet width 240 mm, outlet thickness 1.0 mm, W / T) was 240. The RR in the die 1 is 37. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 60 mm / min. The thickness of the obtained sheet-like molded product was 2.1 mm, and the width was 115 mm.

  Next, this sheet-like molded product was gradually rolled by passing between two metal rolls heated to 60 ° C. four times. The filler-containing PTFE rolled sheet containing the processing aid thus obtained was heated for 5 minutes with a hot air circulating drier kept at a temperature of 120 ° C. to remove kerosene. The thickness of the obtained filler-containing PTFE sheet was 0.1 mm.

(Comparative Example 1)
A preform formed in the same manner as in Example 1 was extruded into a sheet shape using the die shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 106 mm, a length of 800 mm, the first taper portion 4 has a length of 167 mm, a taper angle of 30 °, and the orifice portion 5 has a width of 7.8 mm. , Thickness 28.3 mm, length 10 mm, second taper portion 6 has a length of 99.8 mm, taper angle 60 °, land portion 7 has a length of 100 mm, outlet width 123 mm, outlet thickness 1.8 mm, The (W / T) was 68. The RR in the die 1 is 40. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 60 mm / min. The obtained sheet-like molded product did not expand to the die exit width, and had a non-uniform shape and could not be subjected to the next rolling step.

(Comparative Example 2)
A preform formed in the same manner as in Example 1 was extruded into a sheet shape using the die shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 77 mm, a length of 500 mm, the first taper portion 4 has a length of 112 mm, a taper angle of 30 °, and the orifice portion 5 has a width of 7.8 mm. , Thickness 28.3 mm, length 10 mm, second taper portion 6 has a length of 67 mm, taper angle 35 °, land portion 7 has a length of 20 mm, an outlet width of 50 mm, an outlet thickness of 5 mm. T) was set to 10. The RR in the die 1 is 21. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 30 mm / min. The thickness of the obtained sheet-like molded product was 5.5 mm, and the width was 44 mm.

  Next, this sheet-like molded product was rolled by passing between two metal rolls heated to 60 ° C. However, tearing occurred in the sheet-like molded product during rolling, and a filler-containing PTFE sheet could not be obtained.

(Comparative Example 3)
A preform formed in the same manner as in Example 1 was extruded into a sheet shape using the die shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 106 mm, a length of 800 mm, the first taper portion 4 has a length of 167 mm, a taper angle of 30 °, and the orifice portion 5 has a width of 7.8 mm. , Thickness 28.3 mm, length 10 mm, second taper portion 6 has a length of 413 mm, taper angle 45 °, land portion 7 has a length of 100 mm, outlet width 350 mm, outlet thickness 1.0 mm, W / T) was 350. The RR in the die 1 is 40. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 60 mm / min. However, a uniform sheet-like molded product could not be obtained, and the next rolling process could not be performed.

(Comparative Example 4)
A preform formed in the same manner as in Example 1 was extruded into a sheet shape using the die shown in FIGS. In the die 1 used for the extrusion molding, the cylindrical cylinder portion 3 has a diameter of 106 mm, a length of 800 mm, the first taper portion 4 has a length of 167 mm, a taper angle of 30 °, and the orifice portion 5 has a width of 7.8 mm. 28.3 mm in thickness, 10 mm in length, the second taper portion 6 has a length of 327 mm, a taper angle of 45 °, no land portion 7, the exit width of the die 1 is 123 mm, and the exit thickness of the die 1 is 1.8 mm and the aforementioned (W / T) was 68. The RR in the die 1 is 40. In the extrusion molding, the extrusion temperature was 45 ° C., and the extrusion speed was 60 mm / min. The obtained sheet-like molded product had a corrugated non-uniform shape and could not be subjected to the next rolling step.

  According to the production method of the present invention, a filler-containing PTFE sheet having a sufficiently high strength in the width direction can be obtained. This sheet is used for a wide range of applications, such as a polarizable electrode sheet for electric double layer capacitors, and a dried sheet for organic EL displays.

FIG. 1 is a plan view showing a configuration of an example of an extrusion die according to the present invention. 2 is a cross-sectional view taken along the line II of FIG. 3 is a cross-sectional view taken along line II-II in FIG. FIG. 4 is a diagram showing a part of the cross section in the width direction of an example of the extrusion die of the present invention. FIG. 5 is a diagram showing a part of a cross section in the width direction of an example of an extrusion die according to the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Die 2 Ram 3 Cylinder part 4 1st taper part 5 Orifice part 6 2nd taper part 7 Land part

Claims (3)

An extrusion process for extruding a mixture containing a filler, polytetrafluoroethylene and a processing aid into a sheet using a die, a rolling process for rolling a sheet-shaped product obtained by the extrusion process, and the rolling process And a removal step of removing the processing aid from the rolled sheet obtained by the method of manufacturing a filler-containing polytetrafluoroethylene sheet as a die in the extrusion step and moving in the cylinder portion A possible ram, a first taper portion that continues from the cylinder portion to the outlet side, an orifice portion that continues further to the outlet side than the first taper portion, and a second taper portion that continues further to the outlet side than the orifice portion And a land portion continuing further to the outlet side than the second taper portion, and the taper angle of the second taper portion is 50 ° or less, The length of the end portion is in the range of 20 to 300 mm, and the ratio (W / T) between the outlet width W and the outlet thickness T of the land portion satisfies the relationship of 20 ≦ (W / T) <300. A method for producing a filler-containing polytetrafluoroethylene sheet comprising using a die. The method for producing a filler-containing polytetrafluoroethylene sheet according to claim 1, wherein the sheet-like molded product is rolled so as to have a thickness of 0.1 mm or less. A cylinder portion, a ram movable within the cylinder portion, a first taper portion extending from the cylinder portion to the outlet side, an orifice portion continuing further to the outlet side from the first taper portion, and further from the orifice portion A second taper portion continuing to the outlet side, and a land portion continuing further to the outlet side than the second taper portion, wherein the taper angle of the second taper portion is 50 ° or less, and the length of the land portion Is an extrusion die satisfying a relationship of 20 ≦ (W / T) <300 in which the ratio (W / T) between the outlet width W and the outlet thickness T of the land portion is 20 to 300 mm. .

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