DE19813387C2 - Process for producing a tubular hollow body from polytetrafluoroethylene or from a PTFE recyclate - Google Patents

Description

The invention relates to a method for manufacturing of a tubular hollow body made of polytetrafluoroethylene (PTFE) or from a recycled PTFE.

In order to be able to transport aggressive fluids, it is in known areas of technology, tubular Hollow bodies (e.g. pipes, containers) made of PTFE or a To produce recycled PTFE. For this, both the Ram and paste extrusion is also used.

With ram extrusion, however, only hollow bodies can be used comparatively large wall thickness using virgin PTFE or PTFE recyclate. The The wall thickness is in the range <about 3.0 mm.  

In contrast, the hollow body is smaller in wall thickness per, especially thin-walled pipes, are made using the Paste extrusion manufactured. However, a PTFE paste is relatively expensive and they are also comparatively complex Equipment necessary. The economy of pastes extrusion is therefore inherently limited.

In the scope of DE-OS 20 15 747 a method for con Continuous production of longitudinally welded tubular parts ger structures of any length from a plastic film known in which the plastic film has a support element by means of a mold inlet and an unmagneti adjustable guide tube to the slot tube with overlap band edges is formed. The band edges will heated above the melting temperature of the film material and the still plastic band edges immediately after the Heat welded by applying pressure.

Also in the proposal of DE-OS 23 18 045 one Plastic sheet formed into a tube. Here, al However, the web edges designed so hook-shaped that they interlock and thereby lock Act.

EP 0 218 102 A2 describes a device for producing this make a butt seam on a tube from one more layered packaging material by welding the butt joint outlined edges with an underlaid shroud. The two edges of the packaging material web are in the effective area of a high frequency alternating electromagnetic field in led to a certain distance from each other, in Be an induction coil, a separating sword made of elec insulating material protrudes between the edges.

The invention is based on the prior art Task to create a process with which economical way also tubular hollow body with ge ring wall thickness made of PTFE or a PTFE recyclate are adjustable.

The solution to this problem is in the form of several variants seen in the features of claims 1 to 7.

As for the variant according to claim 1, so first by pressing and sintering on the transferred part of its length made of PTFE or a PTFE re cyclat existing compact cylindrical blank witnesses the end in a disc-shaped configuration a weldable plastic, especially a modifi decorated PTFE. The length of this blank ent speaks about the circumferential length of the hollow body to be produced pers.

From this blank are then successively film-like layers of limited length peeled off. The The thickness of each layer corresponds to the wall thickness of the hollow body pers. Their length is the same as the length of the hollow body measure up. Due to the training of the blank, at this layer the longitudinal edge areas from the weldable ren plastic formed.

Each layer then becomes a slotted tube shaped, in such a way that the longitudinal edges  overlap the weldable plastic or lie bluntly in front of each other. These longitudinal edge areas who which is then heated, welded together and then connected ßend cooled under pressure, so that the desired thin-walled tubular hollow body with the desired Wall thickness and length is available.

Within the scope of the variant embodied in claim 2 initially also a compact cylindrical one Blank made by pressing and sintering on the majority of its length is made of PTFE or one Recycled PTFE and disc-shaped configuration at the end ration consists of a weldable plastic.

The length of the blank corresponds approximately to the circumferential length of the hollow body to be generated.

The blank is then turned into a film Layer peeled off, the thickness of the desired wall thickness corresponds to the hollow body. The layer has no be limited length. Rather, it is continuously from that Blank removed and then continuously in such a way a slotted pipe string deformed that the Slit-defining longitudinal edge areas from the sweat ed plastic end of the blank.

After the pipe string has been formed, the longitudinal edge lies either overlap one another or meet them butt against each other. In this position they become him heats, then welded together and ultimately cooled under pressure.

Of the so formed closed in the slot Pipe string can now be hollow bodies of a certain length to be shared.  

A method variant is described in claim 3, according to which tubular hollow body also larger through knife can be generated with a small wall thickness. There at least two blanks are produced, of these Blanks continuously removed film-like layers peels and then these layers in a parallel position Obviously two longitudinal edge areas blunt or overlap pend merged. The joint area or the overlap area is then continuously heated, then welded together and ultimately under pressure cooled down. There is now a double layer in the way described permanently to a pipe string shaped and then the joint area or the over lapping area heated, welded together and un ter pressure is cooled.

Now hollow bodies of the desired length can also be made of them be divided.

In the variant of the inventions described in claim 4 The inventive method is first by pressing and Sintering produces a compact cylindrical blank, wel over its entire length made of PTFE or a PTFE re cyclate exists. The length of this blank corresponds about the circumferential length of a hollow body.

The blank is then successively made of sheets Peeled layers of limited length, the thickness of each because equal to the wall thickness and its length equal to that The length of the desired hollow body is dimensioned.

Subsequently, each peeled layer becomes one Slotted tube with overlapping longitudinal edge areas vice versa forms.  

In the slot between the longitudinal edge areas now a strip of perfluoro alkoxy polymer (PFA) brought in. Then the overlap area becomes heats, the longitudinal edge areas welded together and ultimately the overlap area under pressure cools so that a tubular hollow body is created is.

According to the process variant in claim 5, the abge peel film-like layer to a slit tube shaped that the longitudinal edge areas face each other opposite. In the slot between the longitudinal channels A band of PFA is then inserted into the areas brought, the joint area then heated, then the Slot closed by welding and ultimately the Cooled joint area under pressure, so that a tubular ger hollow body is formed.

While in the last two Vari antenna made exclusively of PTFE or a PTFE re cyclate existing blank is peeled so that successively film-like layers of limited length for a single hollow body is in the frame the embodiment according to claim 6 provided that of a blank made of PTFE or PTFE recyclate continuously peeled off a film-like layer of the desired thickness, then continuously converted to a slotted pipe string is formed, with the longitudinal edge areas overlapping can or face each other, and that at closing between those overlapping each other Long edge areas a strip or between the front a longitudinal band of PFA be incorporated. Then the overlap rich or the joint area heated, then the slot of the pipe string closed by welding and to Finally, the overlap or joint area below  Pressure cooled. Ultimately, the ge in the slot closed tubing hollow body of the desired length abge Splits.

With the method variant characterized in claim 7 it is also possible to make tubular hollow bodies larger Diameter with a small wall thickness continuously to be able to. For this, at least two film-like ones Layers of corresponding blanks peeled off closing longitudinal edge areas of these layers blunt or merged in parallel overlapping and then between the long edge areas erase tapes or strips Perfluoro alkoxy polymer inserted. The butt or overlap The heating area is then continuously heated, then the longitudinal edge areas are welded together and ultimately also continuously under pressure cools. The wider double layer thus formed is then as described continuously to a pipe string shaped, with the free longitudinal edge areas over may rag or lie in front of each other. In the Slits between the longitudinal edge areas are then Continuous tapes or strips of Perfluor-Al inserted koxypolymer, then the butt or overlap areas welded together and finally un ter pressure cooled. Ultimately, this tube stranded the tubular hollow body of the desired length divided.

The tubular ones produced according to the various variants Hollow bodies can be advantageous, especially in the case of heat build-up shear for wastewater treatment and for seawater ent salting plants are used.

The invention is based on in the drawings gene illustrated embodiments explained in more detail.

Show it:  

Figure 1 is a perspective view of a tubular hollow body made of PTFE.

Fig. 2 also in perspective a cylindri's blank as the base material for the hollow body of FIG. 1;

FIG. 3 shows in perspective a manufacturing stage in the production of the hollow body of FIG. 1;

Fig. 4 in perspective a peeled from the blank of Figure 1 film-like layer be certain length.

FIG. 5 shows in end view a deformed into a slit tube foil-like layer according to Fig. 4;

. Fig. 6 is a deformed into a slit tube sheets like layer as shown in FIG 4 according to a further embodiment;

FIGS. 7 and 7a in perspective a schematic representation corresponding to that according to FIG. 3 for the continuous production of a pipe string in two variants;

FIG. 8 is a perspective view of a hollow body divided from the tubular string according to FIG. 7;

. Fig. 9 is a compartment of the tubing string of Fig 7a hollow body in perspective;

Fig. 10 in perspective, a further execution of a blank as a base material for a hollow tubular body 1 form according to Fig.

Fig. 11 in perspective a manufacturing stage, during the production of a hollow body according to FIG. 1;

FIG. 12 is a perspective view of a film-like layer peeled off from the blank according to FIG. 10 with a certain length; FIG.

FIG. 13 is an end view of a sheet-like layer formed into a slit tube with overlapping longitudinal edge areas, as shown in FIG. 12;

FIG. 14 shows the representation of FIG. 13 with a strip of perfluoro-alkoxypoly mer (PFA) inserted into the slot between the longitudinal edge regions;

Figure 15 is a front view of a slot to an edge portions with each other butt-lying longitudinal reshaped sheet-like layer tube of FIG. 12.;

FIG. 16 is the view of Figure 15 with a Zvi the frontal each other lying longitudinal edge portions of the layer's tape inserted from PFA.

FIG. 17 is a perspective view of a herstel development phase in the continuous production of a hollow body of Figure 1 according to another embodiment.

Fig. 18 in the front view of a pipe string according to Fig. 17, it has frontally lying longitudinal edge regions;

FIG. 19 is an end view of a pipe string according to FIG. 17 with a strip of PFA placed between the overlapping longitudinal edge regions;

FIG. 20 shows a representation of the pipe string of FIG. 18 corresponding to FIG. 19;

Fo peeled FIGS. 21 and 22 in a schematic representation the kontinuier Liche generating a string of pipe from two blanks according to Fig. 2 lien-like layers with longitudinal edges chen preparation of a weldable plastic and

Fig. 23 is also a schematic representation of the continuous production of a pipe string of two peeled films using bands or strips of PFA.

In Fig. 1, 1 is a tubular hollow body be certain length L made of polytetrafluoroethylene (PTFE) be. The hollow body 1 has a wall thickness WD ge desired size.

To produce the hollow body 1 is first by pressing and sintering on the predominant part L1 of its length L2 made of PTFE and end-side in disk-shaped configuration 2 made of a weldable plastic, in particular modified PTFE, existing compact blank 3 . The length L2 of the blank 3 corresponds approximately to the circumferential length of the hollow body 1 .

Is from the blank 3 is now shown in FIGS. 3 and 4 peeled off with the aid of a suitable tool 4, a film-like layer 5 having a length L3, which corresponds to the hollow body 1 of length L. This layer 5 is visually dimensioned its thickness D equal to the wall thickness WD. It can also be seen that the longitudinal edge regions 6 of the layer 5 consist of the weldable plastic of the disk-shaped end parts 2 according to FIG. 2, while the central region 7 is formed from PTFE.

The layer 5 according to FIG. 4 is now formed into a slotted tube 8 as shown in FIG. 5, the longitudinal edge regions 6 at the slit 10 overlapping one another. Ultimately, this overlap area ÜB is heated, then welded and finally cooled under pressure, so that a hollow body 1 according to FIG. 1 is formed.

In a manufacturing modification of Figure 6, the layer 5 of Figure 4 wherein the longitudinal edge regions 6, according to.. Into a slotted tube 8 a reshaped a frontal face each other at the slot 10 today. This joint area STB is then heated, then welded and finally cooled under pressure, so that a hollow body 1 is formed as shown in FIG. 1.

While a method was explained in the foregoing with reference to FIGS . 1 to 6, in which sheet-like layers 5 with a length L3, which corresponds to the length L of a hollow body 1 , are peeled off from a blank 3 ( FIG. 2) in succession Fig. 7 illustrates the continuous Liche generation of a pipe string 9 from a blank 3 according to FIG. 2.

Here too, a film-like layer 5 a is first peeled off from the blank 3 with the aid of a suitable tool 4 , the thickness D of which is dimensioned equal to the wall thickness WD of the hollow body 1 . This peeled layer 5 a is then continuously formed into the tubular string 9 , where the longitudinal edge regions 6 shown in FIG. 7 can overlap or consist of a weldable plastic or lie frontally in front in the tubular string 9 a according to FIG. 7 a.

Following this, the overlap area ÜB or the joint area STB is heated, then welded and finally cooled under pressure. From the tubular string 9 , 9 a closed in the slot 10 b, 10 c, tubular hollow bodies 1 of the desired length L are then divided as shown in FIGS. 8 and 9.

In the Fig. 10 in perspective a compact zy lindrischer a blank 3 is illustrated, which consists over its entire length L4 of PTFE. The length L4 of the blank 3 a corresponds approximately to the circumferential length of the Hohlkör pers 1 of FIG. 1.

Is from the blank 3 a shown in Fig. 10 then in accordance with the illustrations of FIGS. 11 and 12 with the aid of a suitable tool 4, a film-like layer 5 b abge shells whose thickness D equal to the wall thickness WD and the length L5 (Fig. 12) is equal to the length L of the hollow body 1 according to FIG. 1.

The film-like layer 5 b is then formed according to FIG. 13 into a slotted tube Bb, in which the longitudinal edge regions 6 a overlap at the slit 10 d. Between the overlapping longitudinal edge regions 6 a, a strip 11 made of perfluoro-Al koxypolymer (PFA) is then introduced according to FIG 1 according to FIG. 1 is present.

Alternatively, the film-like layer 5 b in FIG. 12 but also according to the illustration of FIG. 15 are converted into a slotted tube 8 c, in which the longitudinal edge portions 6a to each other frontally gegenüberlie gene. In the thus formed slot 10 e is then in accordance with Fig. 16 introduced a tape 12 made of PFA and then the joint area STB1 is also heated, then welded and finally cooled, so that a hollow body is formed by 1 corresponding to FIG. 1.

FIG. 17 illustrates the continuous production of a tubular pipe string 9 b from a blank 3 a according to FIG. 10.

Here, too, with the aid of a suitable tool 4, a film-like layer 5 c with a thickness D is continuously peeled off from the blank 3 a, which corresponds to the wall thickness WD of a hollow body 1 . The layer 5 c is then continuously formed into the slotted pipe string 9 b, in which the longitudinal edge regions 6 b overlap to form a slit 10 f.

However, it is also conceivable that, according to FIG. 18, the longitudinal edge regions 6 b of a tubing string 9 c lie in front of one another to form a slot 10 g.

After forming into a slotted pipe string 9 b, 9 c according to FIGS . 17 or 18, a strip 11 made of PFA between the overlapping longitudinal edge regions 6 b is also placed continuously according to FIG. 19 or it is placed between the frontally 20, a tape 12 made of PFA is inserted against opposite longitudinal edge areas 6 b according to FIG. 20. Then the slots 10 f, 10 g are closed by heating, welding and cooling under pressure of the overlap area ÜB1 or the butt area STB1.

Subsequently, the ge in the slot 10 f, 10 g closed tubing 9 b, 9 c to tubular hollow bodies 1 desired length L as shown in FIG. 1 can be divided.

Fig. 21 illustrates the production of pipe strands 9 c from two film-like layers 5 a. These layers 5 a are peeled in the manner described with reference to FIG. 7 by two blanks 3 which, over the major part of their length, are made of PTFE or a PTFE re-cyclate and have a disc-shaped configuration 2 at the end of a weldable plastic, in particular modified PTFE.

After peeling, the layers 5 a are continuously brought together in such a way that two adjacent longitudinal edge regions 6 c overlap one another. This overlap area ÜB2 is then continuously heated, then welded and finally cooled under pressure. A double layer 13 is created .

This double layer 13 is then continuously deformed to form a pipe string 9 e in which the free longitudinal edge regions 6 d overlap. The overlap area ÜB3 is then heated further in a continuous process, then welded and finally cooled under pressure. The slot 10 h of the tubing 9 e is closed.

From the tubular string 9 e formed in this way tubular hollow body 1 of the desired length can then be divided.

Fig. 22 shows in an analogous representation to FIG. 21, the production of a pipe string 9 f from two foil-like layers 5 a, which are peeled off from two blanks 3 according to FIG. 2.

In this embodiment, the two layers 5 a are brought together with the longitudinal edge regions 6 e so that they abut each other. The joint area STB2 is then continuously heated, then welded and finally cooled under pressure. There is a double layer 13 a. This double layer 13 a is now just if continuously formed into the pipe string 9 f, in which the free longitudinal edge regions 6 f are bluntly in front of each other. The joint area STB3 is then heated in a continuous process, then welded and finally cooled under pressure. The slot 10 i of the pipe strand 9 f is then closed.

The embodiment of the production of a pipe string 9 g, 9 h illustrated in FIG. 23 is based on two blanks 3 a, which according to FIG. 10 consist of PTFE or a PTFE recyclate over the entire length.

Also from these blanks 3 a a fo lien-like layer 5 is then in each case peeled c and g are subsequently ßend adjacent longitudinal edge portions 6, 6 of the two layers h 5 c so combined that they butt presets the other lying or overlapping. Then either a band 12 or a strip 11 of a perfluoro-alkoxy polymer is continuously incorporated between the lying longitudinal edge regions 6 g or the overlapping longitudinal edge regions 6 h. Now the joint area STB4 or the overlap area ÜB4 is heated, then welded and then cooled under pressure.

These broad double layers 13 b, 13 c formed in this way are now continuously deformed to form the tubular string 9 g, 9 h, the longitudinal edge regions 6 i, 6 k lying bluntly in front of one another or overlapping. Between the longitudinal edge regions 6 i, 6 k, either a band 12 or a strip 11 of perfluoro-alkoxy polymer is then incorporated and the joint region STB5 or overlap region UB5 is then heated, then welded and finally cooled under pressure.

Tubular hollow bodies 1 of the desired length can then be divided from the tubular strands 9 g, 9 h produced in this way.

Reference list

1

Hollow body

2nd

disk-shaped configuration

3rd

blank

3rd

a blank

4th

Tool

5

layer

5

a layer

5

b layer

5

c layer

6

Longitudinal edge areas

6

a Long edge areas

6

b Long edge areas

6

c Longitudinal edge areas

6

d Long edge areas

6

e Long edge areas

6

f Long edge areas

6

g Long edge areas

6

h Long edge areas

6

i Long edge areas

6

k Long edge areas

7

Middle range v.

5

8th

Slotted tube

8th

a slotted tube
Bb slotted tube

8th

c slotted tube

9

Pipe string

9

a tubing string

9

b pipe string

9

c pipe string

9

d tubing string

9

e pipe string

9

f pipe string

9

g pipe string

9

h pipe string

10th

slot

10th

a slot

10th

b slot

10th

c slot

10th

d slot

10th

e slot

10th

f slot

10th

g slot

10th

h slot

10th

i slot

10th

k slot

10th

l slot

11

Stripes

12th

tape

13

Double layer

13

a double layer

13

b double layer

13

c double layer
D thickness of

5

,

5

a,

5

b,

5

c
L length from

1

L1 partial length of

3rd

L2 length from

3rd

L3 length from

5

L4 length from

3rd

a
L5 length from

5

b
WD wall thickness from

1

ÜB overlap area v.

6

ÜB1 overlap area from

6

a
ÜB2 overlap area from

6

c
ÜB3 overlap area from

6

a
ÜB4 overlap area from

6

H
ÜB5 overlap area from

6

k
STB joint area v.

6

STB1 joint area from

6

a
STB2 joint area from

6

e
STB3 joint area from

6

f
STB4 joint area from

6

G
STB5 joint area from

6

i

Claims (7)

1. A process for producing a tubular Hohlkör pers ( 1 ) made of polytetrafluoroethylene (PTFE) or from a recycled PTFE, in which first by pressing and sintering on the predominant part (L1) of its length (L2) made of PTFE or a PTFE Recyclate and end-side in disk-shaped configuration ( 2 ) from a weldable plastic, in particular modified PTFE, existing compact cylindrical blank ( 3 ) is produced, the length (L2) of which corresponds approximately to the circumferential length of the hollow body ( 1 ), whereupon the blank ( 3 ) a film-like layer ( 5 ) is peeled off, the thickness (D) equal to the wall thickness (WD) and with respect to its length (L3) equal to the length (L) of the hollow body ( 1 ) is dimensioned, that the Layer ( 5 ) is formed into a slotted tube ( 8 , 8 a) in such a way that the longitudinal edge regions ( 6 ) delimiting the slit ( 10 , 10 a) consist of the weldable plastic, and that ultimately the L longitudinal edge areas ( 6 ) are heated, butt-welded or overlapped, and then cooled under pressure. 2. Process for the production of a tubular Hohlkör pers ( 1 ) made of polytetrafluoroethylene (PTFE) or from a recycled PTFE, in which first by pressing and sintering on the major part (L1) of its length (L2) made of PTFE or a PTFE Recyclate and end-side in disk-shaped configuration ( 2 ) from a weldable plastic, in particular modified PTFE, existing compact cylindrical blank ( 3 ) is produced, the length (L2) of which corresponds approximately to the circumferential length of the hollow body ( 1 ), whereupon the blank ( 3 ) a film-like layer ( 5 a) is continuously peeled off, which is dimensioned with respect to its thickness (D) equal to the wall thickness (WD) of the hollow body ( 1 ), so that the peeled layer ( 5 a) then continuously to one ge slotted pipe string ( 9 , 9 a) is deformed that the slot ( 10 b, 10 c) delimiting longitudinal edge areas ( 6 ) consist of the weldable plastic, whereupon the Längska nten areas ( 6 ) continuously heated, then butt-welded or overlapping with each other and then cooled under pressure who, and that ultimately from the pipe string ( 9 , 9 a) closed in the slot ( 10 b, 10 c) hollow body ( 1 ) be of the right length (L). 3. A process for producing a tubular Hohlkör pers ( 1 ) made of polytetrafluoroethylene (PTFE) or from a recycled PTFE, in which initially by pressing and sintering at least two on the major part (L1) of its length (L1) made of PTFE or one PTFE re-cyclate and end-side in disc-shaped configuration ( 2 ) made of a weldable plastic, in particular modified PTFE, existing compact cylindrical blanks ( 3 ) are produced, the length (L2) of which is in each case a partial length of the circumferential length of the hollow body ( 1 ) correspond to what from the blanks ( 3 ) are continuously peeled off film-like layers ( 5 a), which are dimensioned in terms of their thickness (D) equal to the wall thickness (WD) of the hollow body ( 1 ), that then two longitudinal edge areas ( 6 e, 6 c ) of the layers ( 5 a) leads bluntly or overlapping, the joint area (STB2) or the overlap area (ÜB2) is heated continuously, then to a double layer ( 13 a, 13 ) are welded together and then cooled, whereupon the double layer ( 13 a, 13 ) is continuously deformed into a slotted pipe string ( 9 f, 9 e) in such a way that the longitudinal edges delimiting the slot ( 10 i, 10 h) ( 6 f, 6 d) be made of the weldable plastic, and that these longitudinal edge areas ( 6 f, 6 d) are now continuously heated, then butt-welded or overlapped and then cooled under pressure, and that ultimately from the slot ( 10 i, 10 h) closed tubing ( 9 f, 9 e) hollow body ( 1 ) certain length (L) abge divides. 4. A process for producing a tubular Hohlkör pers ( 1 ) made of polytetrafluoroethylene (PTFE) or from a recycled PTFE, in which first by pressing and sintering over its entire length (L4) made of PTFE or a recycled PTFE compact cylindrical Blank ( 3 a) is produced, the length (L4) of which corresponds approximately to the circumferential length of the hollow body ( 1 ), whereupon a blank ( 5 b) is peeled off from the blank ( 3 a), the thickness (D) of which is equal to that Wall thickness (WD) and its length (L5) equal to the length (L) of the hollow body ( 1 ) is dimensioned such that the peeled layer ( 5 b) is then formed into a slotted tube ( 8 b) with overlapping longitudinal edge regions ( 6 a) Then that in the slot ( 10 d) between the longitudinal edge areas ( 6 a) a strip ( 11 ) of perfluoro-alkoxypoly mer (PFA) is introduced, the overlap area (ÜB1) heated, the longitudinal edge areas ( 6 a) welded together and ultimately the overlap area (ÜB1) can be cooled under pressure. 5. A process for the production of a tubular hollow body ( 1 ) made of polytetrafluoroethylene (PTFE) or a recycled PTFE, in which first a compact blank existing over its entire length (L4) made of PTFE or a recycled PTFE (by pressing and sintering ( 3 a) is produced, the length (L4) of which corresponds approximately to the circumferential length of the hollow body ( 1 ), whereupon a film-like layer ( 5 b) is peeled off from the blank ( 3 a), the thickness (D) of which is equal to the wall thickness (WD) and whose length (L5) is equal to the length (L) of the hollow body ( 1 ), so that the peeled layer ( 5 b) to form a slotted tube ( 8 c) with mutually frontal longitudinal edges ( 6 a) is formed in such a way that then in the slot ( 10 e) between the longitudinal edge areas ( 6 a), a tape ( 12 ) made of perfluoro-alkoxy polymer (PFA) is introduced, the joint area (STB1) is heated, the longitudinal edge areas ( 6 a) are welded together and, finally, the Shock rich (STB1) can be cooled under pressure. 6. A process for producing a tubular Hohlkör pers ( 1 ) made of polytetrafluoroethylene (PTFE) or from a recycled PTFE, in which initially by pressing and sintering a compact blank consisting of PTFE or a recycled PTFE over its entire length (L4) (3 a) is generated, the length (L4) corresponds approximately to the circumferential length of the hollow body (1), followed by a film-like layer (5 c) continuously peeled off from the blank (3 a), the thickness (D) equal to the wall thickness ( WD) of the hollow body ( 1 ) is dimensioned such that the layer ( 5 c) continues continuously to form a tubular string ( 9 b, 9 c) with overlapping longitudinal edge regions ( 6 b) or with frontally lying longitudinal edge regions ( 6 b) is formed that then a strip ( 11 ) of perfluoro-Al koxypolymer (PFA) between the overlapping longitudinal edge areas ( 6 b) or a band ( 12 ) of PFA between the longitudinal edge areas in front of each other ( 6 b) e it is then integrated that the overlap area (ÜB1) or the joint area (STB1) heats it, then the slot ( 10 f, 10 g) of the pipe string ( 9 b, 9 c) is closed by welding, and then the overlap area (ÜB1) or the joint region (STB1) to be cooled under pressure, and finally the (b 9, 9 c) in the slot (10 f, 10 g) closed tubing in the hollow body (1) of predetermined length (L) is divided up. 7. A process for producing a tubular Hohlkör pers ( 1 ) made of polytetrafluoroethylene (PTFE) or from a recycled PTFE, in which first by pressing and sintering at least two over its entire length (L4) made of PTFE or a recycled PTFE best compact blanks ( 3 a) are generated, the added lengths of which correspond approximately to the circumferential length of the hollow body ( 1 ), whereupon the blanks ( 3 a) continuously peel off a film-like layer ( 5 c), the thickness (D) of which is the same the wall thickness (WD) of the hollow body ( 1 ) is dimensioned such that subsequently two longitudinal edge areas ( 6 g, 6 h) of the layers ( 5 c) are butt-jointed or overlapped, with the longitudinal edge areas ( 6 g ) or between the overlapping longitudinal edge areas ( 6 h) a tape ( 12 ) or a strip ( 11 ) of perfluoro-alkoxy polymer (PFA) is incorporated, that the joint area (p TB4) or the overlap area (ÜB4) it heats, then the longitudinal edge areas ( 6 g, 6 h) are welded together and then cooled, and that the double layer ( 13 c) thus formed is then continuously formed into a slotted pipe string ( 9 g, 9 h) with overlapping longitudinal edge areas ( 6 k) or with frontal longitudinal edge areas ( 6 i) being reshaped so that a strip ( 11 ) of PFA between the overlapping longitudinal edge areas ( 6 k) or a band ( 12 ) PFA inserted between the longitudinal edge areas ( 6 i) lying in front of each other, that then the overlap area (ÜB5) or the joint area (STB5) heated, then the slot ( 10 k, 10 l) of the pipe string ( 9 h, 9 g) by welding closed, then the overlap area (ÜB5) or the joint area (STB5) are cooled under pressure and ultimately determine the pipe string closed in the slot ( 9 g, 9 h) in the hollow body ( 1 ) ter length (L) is divided.