WO1999062696A1 - Procede de production de pieces moulees en polytetrafluoroethylene modifie au moyen d'un moulage par raccordement - Google Patents

Procede de production de pieces moulees en polytetrafluoroethylene modifie au moyen d'un moulage par raccordement Download PDF

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Publication number
WO1999062696A1
WO1999062696A1 PCT/JP1999/002914 JP9902914W WO9962696A1 WO 1999062696 A1 WO1999062696 A1 WO 1999062696A1 JP 9902914 W JP9902914 W JP 9902914W WO 9962696 A1 WO9962696 A1 WO 9962696A1
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WO
WIPO (PCT)
Prior art keywords
joining
radius
preformed
preformed part
modified polytetrafluoroethylene
Prior art date
Application number
PCT/JP1999/002914
Other languages
English (en)
Japanese (ja)
Inventor
Osamu Shirasaki
Shingo Tanigawa
Original Assignee
Daikin Industries, Ltd.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Daikin Industries, Ltd. filed Critical Daikin Industries, Ltd.
Publication of WO1999062696A1 publication Critical patent/WO1999062696A1/fr

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Classifications

    • 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
    • B29C65/00—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor
    • B29C65/66—Joining or sealing of preformed parts, e.g. welding of plastics materials; Apparatus therefor by liberation of internal stresses, e.g. shrinking of one of the parts to be joined
    • 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
    • B29C66/00—General aspects of processes or apparatus for joining preformed parts
    • B29C66/70—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material
    • B29C66/71—General aspects of processes or apparatus for joining preformed parts characterised by the composition, physical properties or the structure of the material of the parts to be joined; Joining with non-plastics material characterised by the composition of the plastics material of the parts to be joined
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
    • B29K—INDEXING SCHEME ASSOCIATED WITH SUBCLASSES B29B, B29C OR B29D, RELATING TO MOULDING MATERIALS OR TO MATERIALS FOR MOULDS, REINFORCEMENTS, FILLERS OR PREFORMED PARTS, e.g. INSERTS
    • B29K2027/00—Use of polyvinylhalogenides or derivatives thereof as moulding material
    • B29K2027/12—Use of polyvinylhalogenides or derivatives thereof as moulding material containing fluorine
    • B29K2027/18—PTFE, i.e. polytetrafluorethene, e.g. ePTFE, i.e. expanded polytetrafluorethene

Definitions

  • the present invention relates to a method for joining and forming modified polytetrafluoroethylene (hereinafter, referred to as “modified PTFE”) molded articles. More specifically, the joining surface is obtained by firing preformed parts of modified PTFE.
  • modified PTFE modified polytetrafluoroethylene
  • the present invention relates to a method for molding modified PTFE, which comprises joining and integrating the modified PTFE.
  • Japanese Patent Publication No. 63-67808 discloses a bonded body of modified PTFE molded bodies.
  • the force bonding is performed by heat-compression bonding, that is, by heating while applying pressure from the outside, and the molded bodies are bonded to each other.
  • This method is suitable for joining thin molded articles such as sheets and films, but when joining thick molded articles, it is necessary to apply excessive pressure similarly to the method described in the aforementioned Hoechst catalog. Deficiency occurs due to shortage.
  • JP-A-55-57429 discloses that a core mold is inserted into a cylindrical mold, and a holding mold is arranged at upper and lower ends of the cylindrical mold, and PTFE is formed in a space formed by the mold.
  • a method is disclosed in which both ends of a sheet are joined by expansion pressure caused by heating. This method requires a preforming die and an expansion bonding die for each product dimension, which is industrially disadvantageous as a method for producing various types of products.
  • the mold since the expansion pressure is used, the mold must be sealed, which makes the operation extremely complicated as a whole.
  • a modified PTFE bow A method is known in which the heating and pressurizing are performed by filling a hopper. Since the compression distance is short at the bottom and the compression distance is long at the side wall, cracks occur near the boundary between the side wall and the bottom, and a good molded product cannot be obtained.
  • An object of the present invention is to solve the above-mentioned drawbacks of the prior art and to provide a joining and forming method of a modified PTFE molded product having a sufficiently strong joint at a joint even in a very large molded product. It is to be.
  • Another object of the present invention is to provide a method for joining and forming a modified PTFE molded article in which the occurrence of defective products is reduced, the dimensional accuracy of the molded article is improved, and the material opening due to cutting of parts is reduced. .
  • Still another object of the present invention is to provide a method for bonding and forming modified PTFE, in which the operation of bonding and forming is extremely simple, and the productivity thereof is greatly improved particularly in mass production.
  • Another object of the present invention is to provide a method for bonding and forming modified PTFE in which cracks and gaps do not occur even in a large stratum corneum.
  • a first modified polytetrafluoroethylene preformed part having a closed inner peripheral joint surface including a curved surface, and an outer peripheral joint conforming to the shape of the inner peripheral joint surface
  • a method of joining and forming a modified polytetrafluoroethylene molded article comprising a second modified polytetrafluoroethylene preformed part having a surface
  • the curved surface of the inner peripheral joining surface of the first modified polytetrafluoroethylene preformed part has a radius r]
  • the outer periphery of the second modified polytetrafluoroethylene preformed part The radius of the curved surface of the joint surface is r. Having a radius r . Is equal to the radius r , Re, or larger.
  • two modified polytetrafluoroethylene preformed parts having different heat shrinkage rates are arranged such that the surfaces to be joined are connected to or close to each other, and the parts are fired.
  • at modified polytetramethylene full O b joining molding of ethylene moldings that integrally bonding at the bonding surface of the component by the inner peripheral bonding surface of the first preformed part is a curved surface of radius r 3 a polygon having the corner portion
  • the outer peripheral bonding surface of the second preformed part is a polygon having a curved surface of radius r 4 in the corner portion
  • the thermal shrinkage of the first preformed part is a second
  • a method for joining and forming a modified polytetrafluoroethylene molded product which is larger than the heat shrinkage of a preformed component.
  • the modified PTFE means a copolymer obtained by copolymerizing a small amount of the following modifying monomer during the polymerization of tetrafluoroethylene (hereinafter referred to as “TFE”).
  • X CF 2 (where X represents hydrogen, fluorine or chlorine, and n represents an integer of 1 to 6) or C 3 F, (OCF
  • the group, Y is a hydrogen atom or a fluorine atom.
  • other fluorine-containing unsaturated monomers other than TFE and these are usually added in an amount of 0.01 to 1.0% by weight based on TFE.
  • the modified PTFE can be used as it is as a powder obtained by polymerization, or as a granulated product obtained by subjecting this powder to a granulation treatment.
  • modified PTFE powder these are collectively called It is called "modified PTFE powder”.
  • an appropriate amount of various fillers for example, glass fiber, graphite fiber, carbon fiber, bronze powder, and the like can be dispersed in the modified PTFE powder. Further, other usual additives may be added.
  • the first preformed part is made until its inner peripheral joining surface is equal to or larger than the outer peripheral joining surface of the second preformed part. Preheat and expand.
  • the second preformed part outer peripheral bonding surface of the curved surface has a radius r 2, than or the radius r 2 is equal to the radius ri
  • the first pre-molded part, to a radius r of the curved surface of the inner peripheral joining surface thereof becomes greater or equal than the radius r 2 of the second outer peripheral bonding surface of the preformed parts curved Preheat and expand.
  • the radius of both parts of the curved surface of the front preheating are equal, of course, the radius of the curved surface of the first preformed part is larger than the radius r 2 of the curved surface of the second preformed part.
  • the two parts are combined such that the inner peripheral joint surface of the first preformed part and the outer peripheral joint surface of the second preformed part are in contact with or close to each other.
  • the preheating temperature is preferably equal to or lower than the melting point of PTFE, but may be slightly higher than the melting point. If the preheating temperature is too high, working at high temperatures may be dangerous, and the temperature of the second preformed part may rise rapidly, causing expansion to cause cracks. It is preferable to lower the heating temperature.
  • the preheating time is a time during which the above-described relationship is achieved between the inner peripheral joint surface of the first preformed part and the outer peripheral joint surface of the second preformed part, for example, the above-described radius relationship is achieved. It may be determined as appropriate depending on the size and shape of the first preformed part.
  • the first and second preformed parts expand when heated and then contract when cooled.
  • the preformed part thermally expands and Z or shrinks at a temperature equal to or higher than the melting point, sufficient pressure is applied to the joint surface of the two parts, and the two parts are joined at the joint surface.
  • the bonding surface during the firing Pressure may become too high and any part, especially the first preformed part, may be destroyed.
  • the ratio (1 "2) to the radius ri of the radius r 2 is 1. 0 0 3 to 1. Preferably 0 1.
  • the radius of the corner is from 1 to 2 of the length of the short side of the rectangle; ⁇ ⁇ 4, especially about 1 ⁇ 2 is preferred.
  • the modified PTF ⁇ preformed part used in the joining molding method of the present invention is a part molded by a compression molding method or another suitable molding method, and its shape is appropriately determined according to the shape of the final molded product. Just choose.
  • the first preformed part is a cylinder with an inner radius r ⁇
  • the second preformed part is a disk with a radius r 2
  • the polygon first preformed part having a curved surface of radius ri to the corner portion, a tubular body having for example an inner peripheral joint face of the rectangle, the second preformed part corner curved radius r 2
  • It is a polygonal plate, for example, a square plate, provided in the portion.
  • the outer shape of the cylinder and the cylindrical body can be in a desired form such as a cylinder or a prism, regardless of the shape of the inner surface.
  • the conditions for producing the modified PTFE preformed part were selected from the same range as in the prior art, the temperature was lower than the melting point of the modified PTFE, and the pressure was such that the modified PTFE powder was sufficiently adhered at the specified temperature and integrated. The pressure is such that a preformed part can be obtained.
  • the upper limit of the heating temperature during calcination is not particularly limited, but if it is too high, the denatured PTF E itself will thermally decompose. Therefore, a temperature lower than the thermal decomposition temperature is usually selected.
  • the rate of temperature rise / fall can also be selected by a conventional method.
  • the heating time is not particularly limited. Heat should be applied so that the part expands and Z or contracts sufficiently to join the joint surfaces with sufficient strength.
  • the joining portion is sufficiently strong even for a large molded product. It is possible to reduce the occurrence of defective products, improve the dimensional accuracy of molded products, and reduce the material loss of parts due to cutting.
  • Inner peripheral bonding surface of the first preformed part used in this joining molding method is a polygon having a song surface of radius r 3 in the corner portion, the outer peripheral bonding surface of the second pre-molded parts having a radius r 4 A polygon having a curved surface at a corner portion, and wherein the heat shrinkage of the first preformed part is larger than that of the second preformed part.
  • radius r 3 is radius! ⁇ Equal to or greater than 4 . If the radius of the joining surface is in such a relationship, the second preformed part can be accommodated in the first preformed part without heating and expanding the first preformed part.
  • Modified PTFE preformed parts having different shrinkage ratios used in the second joining molding method of the present invention can be obtained by various methods.
  • Two or more modified PTFE preformed parts with different shrinkage rates can be obtained by preforming under the same pressure from the same modified PTFE powder. Generally, the higher the pressure, the lower the heat shrinkage of the preformed part.
  • modified PPTFE preformed parts having different heat shrinkage ratios can be obtained under the same preforming conditions.
  • preformed parts from the granulate have a lower heat shrinkage than preformed parts from powders obtained by polymerization.
  • the “heat shrinkage rate” (%) is represented by the shrinkage rate of the outer diameter of a 7 mm-thick disc-shaped molded article formed by a mold having an inner diameter of 65 mm after firing.
  • the shrinkage of this outer diameter is calculated by the following equation:
  • the modified PTFE preformed part has a heat shrinkage of preferably from 0.2 to 10%, more preferably from 0.5 to 2.0%.
  • the difference in heat shrinkage between the two modified PTFE preformed parts is preferably between 0.2 and 9.8%, more preferably between 0.4 and 1.0%.
  • Joining of preformed parts is performed by arranging the surfaces to be joined of the parts in contact with or close to each other, and firing the parts.
  • “disposing the surfaces to be joined close to each other” means that the preformed part expands and Z or shrinks at a temperature equal to or higher than the melting point due to such a difference in heat shrinkage between the preformed parts. This means that sufficient pressure is applied to the joint surface of both parts when the two parts are joined, and the joint surface is at a distance where both parts are joined.
  • the upper limit of the heating temperature during calcination is not particularly limited, but if it is too high, the denatured PTF E itself will thermally decompose. Therefore, a temperature lower than the thermal decomposition temperature is usually selected.
  • the rate of temperature rise / fall can also be selected by a conventional method.
  • the heating time is not particularly limited.
  • the heating may be performed so that the part expands and / or contracts sufficiently and the joining surfaces are joined with sufficient strength.
  • ADVANTAGE OF THE INVENTION According to the method of this invention, even if it is a thick molded product, a joining part is fully bonded sufficiently, generation
  • Modified PTFE (New Polyflon M—111) manufactured by Daikin Industries, Ltd. is compression molded at a pressure of 30 Okgf / cm 2 to form a cylindrical preformed part with an outer diameter of 110 mm, an inner diameter of 80 mm, and a height of 10 Omm. (3 pieces) were created.
  • the diameter is 0.625% larger than the inner diameter of the cylindrical part.
  • the diameter is 1.25% larger than the inner diameter of the cylindrical part
  • the diameter is 1.875% larger than the inner diameter of the cylindrical part.
  • the inside diameter of the cylindrical part is the diameter of the cylindrical part a), b) or c) At that point, the bottom part, which was kept at room temperature, was inserted into the lower part inside the cylindrical part.
  • the temperature was raised to 360 ° C at the speed of 50 ° CZ, and held at that temperature for 6 hours.
  • Modified PTFE (M-111 manufactured by Daikin Industries, Ltd. was compression-molded to form a rectangular part of 10 Omm X 20 Omm with curved corners having a radius of 5 Omm. (Thickness: 15 mm) The heat shrinkage of this part was 4.0%.
  • Modified PTFE (shrinkage rate adjusted by classifying M_1111 manufactured by Daikin Industries, Ltd.) is compression-molded, and the inner diameter of the inner part is 0.05 to 0.5 lmm larger than the outer dimension of the bottom part.
  • a hollow prismatic part (having a rectangular shape of 160 mm x 260 mm and a height of 10 Omm) was created. The heat shrinkage of this part was 5.7%.

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  • Engineering & Computer Science (AREA)
  • Mechanical Engineering (AREA)
  • Lining Or Joining Of Plastics Or The Like (AREA)

Abstract

L'invention se rapporte à un procédé de production de pièces moulées en polytétrafluoréthylène modifié qui consiste à utiliser, d'une part, une première partie prémoulée en polytétrafluoréthylène modifié comportant une surface interne de raccord fermé comprenant une partie incurvée et, d'autre part, une seconde partie prémoulée en polytétrafluoréthylène modifié comportant une surface externe de raccord; à dilater la première partie prémoulée en polytétrafluoréthylène modifié en la chauffant jusqu'à ce que l'aire de sa surface interne de raccord devienne supérieure ou égale à celle de la surface externe de raccord de la seconde partie prémoulée en polytétrafluoréthylène modifié ; à placer la seconde partie prémoulée en polytétrafluoréthylène modifié à l'intérieur de la première partie prémoulée de manière que des surfaces incurvées des deux parties soient disposées l'une face à l'autre; et à soumettre les parties prémoulées à un frittage, de manière à les assembler au niveau de leurs surfaces de raccord et à produire un article moulé monobloc. Ce procédé permet la production d'articles moulés en polytétrafluoréthylène modifié de très grande taille et comportant une partie de raccordement très satisfaisante car fortement soudée.
PCT/JP1999/002914 1998-06-04 1999-06-01 Procede de production de pieces moulees en polytetrafluoroethylene modifie au moyen d'un moulage par raccordement WO1999062696A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP10/156297 1998-06-04
JP15629798 1998-06-04

Publications (1)

Publication Number Publication Date
WO1999062696A1 true WO1999062696A1 (fr) 1999-12-09

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Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5410378A (en) * 1977-06-23 1979-01-25 Daikin Ind Ltd Joining of pipe to pipe or pipe to rod made of polythtrafluoroethylene
JPS6221524A (ja) * 1985-07-23 1987-01-29 Nichias Corp 熱交換器用合成樹脂チユ−ブ束の製造方法
JPH05500780A (ja) * 1989-07-12 1993-02-18 マザー・シール・カンパニー 焼結された複合ポリマ材料
JPH06134869A (ja) * 1992-10-28 1994-05-17 Olympus Optical Co Ltd フッ素樹脂の接合方法
JPH0752253A (ja) * 1993-08-19 1995-02-28 Kiyoshi Fujiwara フッ素樹脂ｐｆａ製配管の溶着管継ぎ手の加工方法
JPH09187865A (ja) * 1996-01-11 1997-07-22 Daikin Ind Ltd フッ素樹脂積層パイプ及びその製造方法

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5410378A (en) * 1977-06-23 1979-01-25 Daikin Ind Ltd Joining of pipe to pipe or pipe to rod made of polythtrafluoroethylene
JPS6221524A (ja) * 1985-07-23 1987-01-29 Nichias Corp 熱交換器用合成樹脂チユ−ブ束の製造方法
JPH05500780A (ja) * 1989-07-12 1993-02-18 マザー・シール・カンパニー 焼結された複合ポリマ材料
JPH06134869A (ja) * 1992-10-28 1994-05-17 Olympus Optical Co Ltd フッ素樹脂の接合方法
JPH0752253A (ja) * 1993-08-19 1995-02-28 Kiyoshi Fujiwara フッ素樹脂ｐｆａ製配管の溶着管継ぎ手の加工方法
JPH09187865A (ja) * 1996-01-11 1997-07-22 Daikin Ind Ltd フッ素樹脂積層パイプ及びその製造方法

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