DE4132984C1 - Gas and liquid impermeable tubing - comprises core tube of polyethylene@ with polyvinylidene fluoride casing - Google Patents

Abstract

Synthetic plastic pipe comprises a core tube (2) and an outer polyvinylidenefluoride (PVDF) tube (3). Pref. the core tube is of polyethylene, opt. with an aluminium outer tube; the PVDF layer is 0.1-1mm thick; the PVDF layer is surrounded with a protective layer (4) of polyethylene; and the pipe is prepd. by coextrusion of the core (2) and outer (3) tube. USE/ADVANTAGE - For protective pipe for cables; for transporting gas or liq. e.g. drinking or waste water etc.. The tube prevents the escape of toxic components from the inside, or the contamination of the pipe contents from the outside, e.g. when the pipe passes through uncontaminated or contaminated earth. The pipe with the barrier layer of PVDF can be produced at low cost.

Description

The invention relates to a plastic tube and a Process for making the same.

There are a large number of applications for plastic pipes possible applications. So z. B. pipes for the Protection of cables used; Farther plastic pipes are used to guide gaseous Media or fluids, such as from drinking water or sewage.

If the plastic pipes for example for the Wei transmission of toxic media should be suitable, it is important that the toxi carried in the tube substances do not get outside the pipe, for example in the surrounding the plastic tube Ground.

On the other hand, it is also important that if art fabric pipes laid in a contaminated environment be such. B. poisoned soil that in media carried in the pipe are not the toxins of the Record the environment. This is especially true with drinking water pipes important.

There is price for the production of plastic pipes valuable plastics that are easy to process let and the more positive properties point, but no absolute diffusion barrier for represent harmful substances.  

Furthermore, the plastic "polyvinylidene fluoride" known, hereinafter abbreviated to PVDF, the has the advantage that it has a very good diffusion tightness against gases and liquids points. Pipes made of PVDF are therefore excellent Diffusion barrier, but are therefore disadvantageous lig because they are very expensive.

From DE-40 04 360 A1 it is known to have thin walls Manufacture pipes from PVDF, which be with internal pressure hits and then with a coat of glass fiber reinforced thermoplastics or unsaturated duro plastic are surrounded, the thin-walled PVDF pipe is welded to the reinforcement pipe. This is an expensive manufacture positioning process, and the pipes thus obtained are therefore can only be used for special purposes the PVDF pipe with the medium to be led immediately bar comes into contact.

In contrast, the invention relates to the known today, on a large scale by extrusion manufactured inexpensive plastic pipes.

The invention is based on the object to create such plastic pipe that both is inexpensive to manufacture, but at the same time absolute diffusion tightness is also guaranteed.

This object underlying the invention will  by teaching the distinctive part of the head claim solved.

In particular, the starting point is the idea an inexpensive to manufacture core tube with a Surrounding jacket made of PVDF, with the jacket made of PVDF the actual diffusion tightness of the Art constructed pipe guaranteed. The Jacket made of PVDF should also be kept very thin, so that the actual mechanical stability of such built tube obtained through the core tube becomes. With this arrangement you get a cost inexpensive to manufacture plastic pipe that due to its combination of a core tube inexpensive plastic and one arranged on it neten diffusion barrier jacket made of PVDF ideal for is many uses.

Further advantageous embodiments of the invention are explained in the subclaims.  

Claim 2 relates to the fact that the core tube made of polyethylene. Polyethylene pipes have a variety of advantages, such as: B. a low weight, easy installation, durability resistance to aggressive flow media and soils as well as good weldability after all currently known methods. When laying such Pipes in floors is also advantageous in that poly ethylene insensitive to frost and resistant against microorganisms as well as a high voltage has crack resistance. With all these advantages Polyethylene is an inexpensive material.

Claim 3 relates to a protective layer that is arranged over the PVDF jacket. This is supposed to Damage to the PVDF jacket can be prevented the z. B. when laying the art of the invention fabric tubes can occur. Furthermore, through the protective layer injuries to the already installed Tube prevented.

This protective layer advantageously consists in accordance with Claim 4 also made of polyethylene, the front parts have already been carried out above.

According to claim 6, the core tube can be an additional Get protection in the form of an aluminum jacket.

It has been shown that very small thicknesses of the PVDF jacket an absolute diffusion barrier for Represent gases and fluids. In practice it has a PVDF jacket with a thickness of 300 or 500 µ has proven itself. The smallest possible thickness of the PVDF jacket is therefore desirable to the lowest possible Consumption of this costly material too  possible and the weight of the plastic pipes like this to keep it as low as possible.

Claim 7 relates to the manufacture of a Plastic tube consisting of a core tube and a the jacket arranged on it consists of PVDF. Here it is particularly advantageous if the core tube and the PVDF jacket are co-extruded. Thereby you get a seamless PVDF jacket that is absolutely is diffusion-tight and in which there is a subsequent No need to weld seams.

This method is particularly advantageous if the Core tube made of polyethylene. Both polyethy len as well as PVDF have a different Shrinkage behavior, and when the PVDF Mantels tightly wraps around the polyethylene core pipe. As a result, the PVDF jacket has one good hold on the core tube, and a subsequent Moving or twisting is prevented.

An embodiment of the invention is shown in the drawing, wherein 1 denotes a plastic tube. This plastic tube 1 be consists of a core tube 2 , which is surrounded by a jacket 3 made of PVDF. A protective layer 4 is provided to protect this thin PVDF jacket 3 .

Claims (7)

1. Plastic tube, characterized in that a jacket ( 3 ) made of polyvinylidene fluoride (PVDF) is arranged on a core tube ( 2 ). 2. Plastic tube according to claim 1, characterized in that the core tube ( 2 ) consists of poly ethylene. 3. Plastic pipe according to claim 1 or 2, characterized in that a protective layer ( 4 ) is arranged around the PVDF-Man tel ( 3 ). 4. Plastic pipe according to claim 3, characterized in that the protective layer ( 4 ) consists of polyethylene. 5. Plastic pipe according to one of the preceding claims, characterized in that the jacket ( 3 ) made of PVDF is 100 µ to 1 mm thick. 6. Plastic tube according to one of the preceding claims, characterized in that the core tube ( 2 ) is additionally surrounded by an aluminum jacket. 7. A method for producing a plastic tube according to claim 1 or 2, characterized in that the core tube ( 2 ) and the jacket ( 3 ) are co-extruded from PVDF.