DE102009047258A1 - Method for manufacturing rotationally-symmetric composite for pipeline system utilized in chemical process industry, involves heating pre-product, such that connection is manufactured between lining and fiber product by using hot-melt - Google Patents

Abstract

The method involves enclosing a steel body with a rotation-symmetrically formed shell foil (1a) made from PTFE. Hot-melt material (2a) is applied on the shell foil. A layer of textile fiber product e.g. cloth or knitted fabric, is applied on compound made from PTFE-hollow body and the hot-melt material. A pre-product is heated in such a manner that the hot-melt makes a sinter welding at junction points and a connection is manufactured between a PTFE-lining and the fiber product by using the hot-melt.

Description

The present invention relates to methods for producing a rotationally symmetric composite material.

Piping systems and apparatus made of fiber-reinforced plastics based on thermoplastic resins are used in the chemical process industry (CPI) for the transport and handling of corrosive and aggressive liquids and gases.

In the case of very high demands on the chemical and thermal suitability, PTFE is used today as a lining material for both piping systems and apparatuses. The construction of such pipes is approximately in the German patent DE 102 03 123 and in the European patent application EP 1 857 259 A1 shown.

As lining material, paste-extruded PTFE is used in inner liners produced in this way. As a result, but then the nominal size is limited upwards by the production process of the liner. PTFE liner pipes of nominal size greater than DN 300 are commercially available only to a limited extent. Consequently, the design of large-sized pipes and apparatuses normally resorted to laminated PTFE peel-off film as a lining material.

The application of the lamination is generally carried out batchwise in heated presses with an intermediate film of perfluorinated plastic such as tetrafluoroethylene-perfluorovinyl ether (FEP), perfluoroalkoxy-tetrafluoroethylene copolymer (PFA), modified perfluoroalkoxy-tetrafluoroethylene copolymer (PFA-M) formerly also tetrafluoroethylene Perfluoromethyl vinyl ether copolymeryl (MFA) at temperatures above 350 ° C. Due to the high PTFE thermal expansion coefficient complex temperature-pressure programs must be adhered to. Also, this makes it difficult to ensure the flatness of the laminated panels.

In addition to the elaborate manufacturing process of the laminated plate material also the deformation of the plates to cylinders and in particular the necessary axial welding of the plate material are time consuming and error prone.

Thus, before lamination, the lamination must first be worked off in the area of the seam and then applied again after welding. This is the only way to minimize the risk of liner detachment from the reinforcement, such as at higher operating temperatures, which may be due to different thermal expansion coefficients of PTFE and the reinforcing material. Without lamination there is no adhesion between the PTFE lining and the reinforcement. In addition, hand-welded seams represent a potential weak point of the lining. The increased proportion of crystallite in the PTFE basic structure that inevitably forms during the rapid cooling of the weld seam can lead to excessive permeation of the process media through the lining structure.

Hence, the object of the invention to provide a method to provide for large diameters cylindrical, fiber-reinforced thermosetting plastic composites with firmly connected PTFE lining, which can be easily manufactured without complicated machines and have adapted to the loads property profile with adhesive shear strengths and adhesive tensile strengths, wherein the axial and circumferential welds should not differ from the base material. This should apply both to the mechanical properties such as strength and stiffness as well as to the material properties such as amorphous content and density.

• a) Ummantelung eines Stahlkörpers mit Schälfolie aus PTFE;
• b) Aufbringung eines Schmelzklebstoff-Materials auf die rotationssymmetrisch geformte Schälfolie aus PTFE;
• c) Applikation mindestens einer Schicht aus einem textilen Faserprodukt (3, 4) auf den so hergestellten lockeren Verbund aus PTFE-Hohlkörper und Schmelzklebstoff; und
• d) Erwärmung es so hergestellten Vorprodukts dergestalt, dass zum einen die Schälfolie an den Nahtstellen miteinander eine Sinterschweißung eingeht und zum anderen mit Hilfe des Schmelzklebstoff eine Verbindung zwischen der PTFE-Auskleidung und dem textilen Faserprodukt hergestellt wird.

To achieve this object, according to the invention, a method for producing a rotationally symmetric composite material, consisting of a lining of PTFE peelable film and a reinforcement of fiber-reinforced plastic specified, comprising the following steps

• a) sheathing a steel body with peeling film made of PTFE;
• b) application of a hotmelt adhesive material to the rotationally symmetrical peel sheet made of PTFE;
• c) application of at least one layer of a textile fiber product ( 3 . 4 ) on the thus prepared loose composite of PTFE hollow body and hot melt adhesive; and
• d) heating it produced precursor in such a way that on the one hand, the peelable film at the joints with each other enters a sintered weld and on the other hand with the aid of the hot melt adhesive, a connection between the PTFE lining and the textile fiber product.

It is therefore a combined sinter welding and laminating process of PTFE linings for pipes and cylindrical components of larger nominal width.

• 1) Kaschieren von PTFE-Tafelmaterial,
• 2) Verformung der kaschierten Tafeln zu zylindrischen Strukturen,
• 3) drittens Abarbeitung der Kaschierung im Nahtbereich
• 4) Axialschweißen sowie Umfangsschweißen und
• 5) Schweißen der Kaschierung im Nahtbereich.

It is thereby created a rotationally symmetric composite material of larger nominal size of a fiber-reinforced plastic reinforcement and a PTFE lining, without the conventional manufacturing process with the process steps

• 1) laminating PTFE sheet material,
• 2) deformation of the laminated panels into cylindrical structures,
• 3) third processing of the lamination in the seam area
• 4) Axialschweißen and circumferential welding and
• 5) Welding of the lamination in the seam area.

The idea of the invention is the combination of lamination and axial welding with optimum weld seam quality.

• – Virginale PTFE-Schälfolie wird auf einem Stahldorn appliziert.
• – Auf die Schälfolie wird eine Lage PFA- bzw. FEP-Folie als Schmelzklebstoff gelegt.
• – Die Kaschierung wird in Form eines textilen Faserproduktes aufgebracht.
• – Dieser Mehrschichtaufbau wird letztendlich mit Gewebeband etwa aus Glas- und/oder Kohlenstofffasern lückenlos umwickelt.
• – Erwärmung der Struktur auf Sintertemperatur ca. 360°C

For this purpose, the above-average thermal expansion coefficient of PTFE is used in comparison to steel:

• - Virginale PTFE peel sheet is applied to a steel mandrel.
• - A layer of PFA or FEP film as a hotmelt adhesive is placed on the peeling film.
• - The lamination is applied in the form of a textile fiber product.
• - This multi-layer construction is finally wrapped with fabric tape such as glass and / or carbon fibers gapless.
• - Heating the structure to sintering temperature about 360 ° C.

The fabric tape prevents the PTFE from expanding in the radial direction, thereby establishing pressure in the radial direction and to the other pressure within the liner. This results in a simultaneous welding of the lamination and the joining edges of the peelable film.

After the structure has cooled down, the fabric tape can then be easily unwound and then traditionally reinforced by a winding process with a fiber-reinforced plastic.

Thus, the present invention encompasses the construction and production process of polytetrafluoroethylene (PTFE) linings for pipes and cylinders, which are connected by lamination to a strength and stiffness-imparting partner.

The linings according to the invention are welded in a single process of sheet material into tubes and simultaneously provided with a lamination in the process step. They can then be provided with a fiber-reinforced plastic reinforcement (FRP).

The linings are used in particular for use in pipeline systems of larger nominal width and process engineering apparatus for the transport and handling of aggressive gaseous and liquid media.

The invention is illustrated by the following schematic sectional drawings 1 to 3 explained in more detail.

In 1 is a prepared at ambient temperature structure shown using the example of a cylindrical body. It depicts the cross-sectional area of the wall. In the schematic drawings, the inside of the structure is located at the bottom. The PTFE lining 1 is suitably applied to a metal mold not shown here. 1a denotes within the PTFE lining the peelable film and 1b a prepared prepared weld center.

Above the PTFE liner is the hot melt adhesive 2a loosely applied from FEP or PFA. This is also loosely the textile fiber product, shown here in the form of a fabric consisting of weft threads 3 and warp threads 4 , and the cover fabric 5 applied.

This structure is then heated to a temperature at which the hot melt adhesive 2a melts, the peeling film 1a in a gel-like state and an adhesive bond also due to the thermal stresses between the lining 1 and the textile fiber product 3 . 4 generated.

After cooling, the cover fabric 5 removed, and the structure corresponds to the figure 2 with the lining 1 , the sinter welded seam 1c and by the molten hot melt adhesive 2 bonded textile fiber product 3 . 4 ,

3 does that with a fiber reinforced plastic reinforcement 6 reinforced end product 2 represents.

LIST OF REFERENCE NUMBERS

1

PTFE lining

1a

foil

1b

Foil interface before welding

1c

Foil seam after sintering

2a

PFA or FEP hot melt adhesive before heating

2 B

PFA or FEP hotmelt adhesive after heating

3a

Weft of a fabric before warming

3b

Weft of a fabric after heating

4a

Warp thread of a fabric before heating

4b

Warp thread of a fabric after heating

5

Deckgewebe

6

Fiber reinforced plastic reinforcement

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10203123 A [0003]
• EP 1857259 A1 [0003]

Claims (10)

Method for producing a rotationally symmetric composite material, consisting of a lining made of PTFE peelable foil ( 1 ) and a reinforcement made of fiber-reinforced plastic ( 6 ), comprising the following steps: a) coating of a steel body with a peeling film made of PTFE, b) application of a hotmelt adhesive material to the rotationally symmetrical peel film made of PTFE, c) application of at least one layer of a textile fiber product ( 3 . 4 ) on the thus prepared loose composite of PTFE hollow body and hot melt adhesive; and d) heating the precursor thus produced in such a way that, on the one hand, the peeling film undergoes sinter welding together at the seams and, on the other hand, a connection is established between the PTFE lining and the textile fiber product with the aid of the hot melt adhesive. A method according to claim 1, characterized in that the hot melt adhesive is applied in the form of a rotationally symmetrical hollow body on the PTFE peelable film. Method according to one of the preceding claims, characterized in that after applying the at least one layer of a textile fiber product, a further layer of a textile fiber product is applied, which acts as an abutment in the heating of the precursor and thus ensures that the product is a rotationally symmetric Shape keeps. Method according to one of the preceding claims, characterized in that the product obtained after the heating of the precursor and optionally removal of the further layer of textile fiber product is reinforced with a plastic. Method according to one of the preceding claims, characterized in that the layers of textile fiber products are textile tubes or textile winding layers. Method according to one of the preceding claims, characterized in that it is the hot melt adhesive is a material containing a perfluorinated plastic such as PFA, PFA-M or FEP. Method according to one of the preceding claims, characterized in that the textile fiber products are woven, laid or knitted fabrics. Method according to one of the preceding claims, characterized in that the fibers of the textile fiber products consist of a substance whose melting point is significantly above the melting point of PTFE. Method according to one of the preceding claims, characterized in that the PTFE lining has a thickness of between 1 mm and 20 mm inclusive, and the hot-melt adhesive layer has a thickness of between 10 μm and 2000 μm inclusive. Method according to one of the preceding claims, characterized in that for the preparation of an antistatic PTFE and / or an antistatic set reinforcing plastic is used.

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