DE3942353A1 - Strong, flexible laminar thermoplastic pipe - has innermost impervious lining bonded to mechanically strong layer, then braiding for reinforcement, and outermost thermoplastic sleeve - Google Patents

Abstract

A laminar wall thermoplastic pipe for use in safety systems has an inner pipe, bonding layer, braiding and an outer pipe. The inner pipe consists of two layers bonded together, one of which is cross-linked; this inner liner is bonded to the braiding and then the outermost pipe. Prefd. materials are polyamide for the innermost and outermost layers, and a thermoplastic resin for the adhesive used. To improve the mechanical strength of the end prod. it can contain two layers of braiding instead of one. The two layers making up the inner pipe are used because the one provides the mechanical strength and the other the imperviousness to the liq. or gas passing through. The two can be coextruded. Alternatively a cross-linking operation can be used. The braiding layer assists in transmitting stresses from one face to the other. ADVANTAGE - The structure of the pipe makes it impervious to liqs. carried (e.g. liqs. which are environmentally unfavourable). They are flexible yet resistant to buckling. They withstand high pressure and temp. and are wear-resistant.

Description

The invention relates to a multi-layer security hose made of thermoplastic materials low through rate of non-flammable fluids, e.g. B. of halogen hydrocarbons, which has a uniform inner tube, which consists of two cohesively connected layers, one of which is networked, this in another Adhesive layer adhesive and non-positive with a braid is connected and has an outer layer.

Safety parts are generally used in automotive construction relevant parts and components referred to, the special Requirements have to meet, in process-reliable procedures be produced and a tightened quality control and documentation are subject to. This includes refrigerants tubing in addition to the pulse strength and the creep test like the permeability when the temperature changes keitsrate of the fluids in which z. Z. from environmental protection establish z. B. the stricter US limit of 2 g of refrigerant loss per running meter of hose Nominal size 1/2 ′ ′ under certain test conditions in 24 Hours is committed, with a tendency to another Reduction.  

Special elastomer hoses have good flexibility and buckling stability for certain För applications change of fluids, e.g. B. of refrigerants based of halogenated hydrocarbons for air conditioners from Fahr testify to a relatively high permeability rate through the walls. This leads to environmental pollution, those with increasing external temperature stresses is increased. The properties are improved by the use of thermoplastics at low Flexibility and kink stability through a four-layer Structure of the hose: single-layer inner tube, adhesive layer, Braid and outer layer.

Based on this known prior art Invention based on the object of a multi-layer security safety hose with thermoplastic materials form that the permeability rate for fluids further re is reduced with sufficient flexibility and kink stability as well as a very good pressure, tempe temperature change and wear behavior, d. H. one there appropriate fatigue strength.

This task is solved with the characteristics the labeling part of claim 1.  

The inner tube is called a thermoplastic-integral Unity in the form of an inner layer and an outer layer Layer formed. One layer gives this Pipe good mechanical strength; the other layer is constructed so that a very low permeability fluidity rate arises. That will be achieved on the one hand in that the material bond of the layers in the plasticized state at the same time with the strand pressing is achieved by the method of co-extrusion; on the other hand, by a subsequent Networking process by a physical or chemical process is effected, which is thermo in itself plastic molecular structure e.g. T. is changed and that Material properties of cross-linked plastics. These Measures result in a differentiated optimization of the dimensions material properties for the intended individual case.

The mechanical strength of the hose becomes essential co-determined by the network. The is affected supporting function of the braid through the implementation of the Forces from the outer diameter of the inner tube over the ent speaking design of the adhesive layer by an Er increase in the adhesive properties of this layer and by the Adhesive layer on the inner tube. Further measures one Improvement of the connection from the inner tube to the braid can be achieved

• - by a uniform material bond between the outer Layer of the inner tube and the adhesive layer and or
• - By a hot melt adhesive as an adhesive layer, which the chemically dissolves the outer layer of the inner tube.

The temperatures that occur in the event of a fire are sufficient for the safety hose to function is impaired, the incombustible fluid escapes and can lead to environmental pollution; that works the addition of flame retardant fabrics on its exterior effectively counteracts.

In Fig. 1 is a longitudinal section through a portion of the safety tube. With ( 1 ) the entire inner tube is designated; its two layers are the inner layer ( 5 ) and the outer layer ( 6 ). ( 2 ) denotes the adhesive layer applied to the outer diameter of the outer layer ( 6 ) of the inner tube ( 1 ); ( 3 ) is the overlying braid and ( 4 ) is the outer layer of the safety hose ( 7 ).

In an embodiment of the safety hose ( 7 ), not shown, the braid ( 3 ) can in turn consist of two braid layers; this further increases the strength of the hose.

Reference numerals

1 inner tube
2 adhesive layer
3 braid
4 outer layer
5 inner layer
6 outer layer
7 safety hose

Claims (12)

1. Multi-layer safety hose made of thermoplastic plastics, consisting of an inner tube, an adhesive layer, a braid and an outer layer, characterized in that the uniform inner tube ( 1 ) from an inner layer ( 5 ) with a cohesively connected outer layer ( 6 ) is constructed, in which a layer is cross-linked, this is given in a further adhesive layer ( 2 ) in a non-positive and adhesive manner by a braid ( 3 ) and the hose ( 7 ) has an outer layer ( 4 ). 2. Multi-layer safety hose according to claim 1, characterized in that the inner layer ( 5 ) is cross-linked. 3. Multi-layer safety hose according to claim 1 or 2, characterized in that the outer layer ( 6 ) is cross-linked. 4. Multi-layer safety hose according to one or more of claims 1 to 3, characterized in that the thermoplastic material of the inner layer ( 5 ) or the outer layer ( 6 ) is crosslinked by radiation. 5. Multi-layer plastic hose according to one or more of claims 1 to 4, characterized in that the thermoplastic material of the inner layer ( 5 ) or the outer layer ( 6 ) is chemically cross-linked. 6. Multi-layer safety hose according to one or more of claims 1 to 5, characterized in that the inner layer ( 5 ) consists of polyamide. 7. Multi-layer safety hose according to one or more of claims 1 to 6, characterized in that the outer layer ( 6 ) consists of polyamide. 8. Multi-layer safety hose according to one or more of claims 1 to 7, characterized in that the adhesive layer ( 2 ) consists of a thermoplastic material. 9. Multi-layer safety hose according to one or more of claims 1 to 8, characterized in that the uniform inner tube ( 1 ) is integrally constructed with the adhesive layer ( 2 ). 10. Multi-layer safety hose according to one or more of claims 1 to 9, characterized in that the adhesive layer ( 2 ) consists of a hot melt adhesive acting on the outer layer ( 6 ) of the thermoplastic inner tube ( 1 ). 11. Multi-layer safety hose according to one or more of claims 1 to 10, characterized in that the braid ( 3 ) consists of two layers of braid. 12. Multi-layer safety hose according to one or more of claims 1 to 10, characterized in that the outer layer ( 4 ) contains flame-retardant substances.