GB2117482A

GB2117482A - Flexible hose having moisture barrier

Info

Publication number: GB2117482A
Application number: GB08307943A
Authority: GB
Inventors: Daniel Polasky
Original assignee: Eaton Corp
Current assignee: Eaton Corp
Priority date: 1982-04-01
Filing date: 1983-03-23
Publication date: 1983-10-12
Also published as: JPS58203280A; CA1192850A; GB8307943D0; DE3311877A1; GB2117482B; AU1310983A; AU551389B2

Abstract

Flexible hose (11) has a composite core tube (1) comprising an inner annular layer (2) of thermoplastic polyethylene and an outer annular layer (3) of thermoplastic rubber material that is melt fused to the inner layer (2). The polyethylene layer provides a barrier against penetration of moisture into fluid being conveyed and the rubber layer permits reduction of the wall thickness of the polyethylene layer so as to improve flexibility and reduce tendency to kink when bent as well as enabling the hose reinforcement (4, 7, 8) to be secured tightly to the polyethylene inner layer by being bonded to the rubber outer layer. <IMAGE>

Description

SPECIFICATION Flexible hose having moisture barrier This invention relates generally to flexible hose for use in the conveyance of fluids and concerns flexible hose having a barrier to the penetration of moisture into the fluid being conveyed.

Flexible hose has been used for many years to convey a variety of fluids from one point to another.

In some instances the fluid being conveyed through the hose is of a type that would be adversely affected in the event that it was exposed to moisture such as water vapor during its presence in the hose. Unfor tunately, excepting for certain costly and difficult to process fluorinated polymers, the type of materials commonly used to make hoses such as natural and synthetic rubber, nylon, polyester and polyurethane materials have characteristically possessed poor resistance to penetration by moisture. Additional components, such as costly metal tapes or metal plastic laminates, have been required to be disposed about the core tube to prevent moisture from penetrating through the core tube and contaminat ing the fluid being conveyed through the hose.

Some hose constructions have become more sophisticated by the use of core tubes having multiple layers rather than a single layer as was common practice in the past. An example of a multiple layered core tube in a hose construction can be found in United States Patent 2,564,602 in which the core tube has an inner layer made from a relatively soft rubber and an outer layer made from a harder polymeric material such as nylon, polyamide chloride or polyethylene for protecting the inner rubber layer from damage by metal braid reinforce ment disposed about the core tube.An example of a coextruded tube of polyurethane and polyvinyl chloride can be found in United States Patent 3,411,981 which features a polyurethane layer melt fused to either or both the inner and outer surface of the polyvinyl chloride layer to improve the strength of the polyvinyl chloride layer. An example of a composite tube having multiple layers is found in United States Patent 2,561,493 in which two or more adjacent layers of different materials are bonded together by an intermediate layer made up of a mixture of the materials from which the layers desired to be bonded together are made.

Although polyolefin polymers such as polyethylene are considerably lower in cost than fluorocarbonated polymers and are known to pro vide a good barrier against moisture penetration, their use as a core tube in hose constructions has heretofor been limited due to their greater inherent stiffness compared to more conventional hose mate rials and to their tendency to kink in tube form.

Additionally, it has not been satisfactorily demons trated that polyolefin polymers in tube form can be W suitably bonded to encompassing reinforcement material which bonding would reduce their tendency to kink. Polymer compositions commonly used in hose constructions such as plasticized nylon, neop rene and NBR contain additives to improve flexibil ity, processing and other properties which over a period of time are able to migrate into and contaminate the fluid being conveyed through the hose.

Polyolefins such as polyethylene do not require such additives and are frequently used in food and drug applications where contamination is of concern.

None of the prior-art hose, whether having a composite core tube or not, have heretofor addressed the problem of preventing moisture from penetrating through the core tube and contaminating the fluid without encountering the problem of flexibility and bonding associated with polyolefin materials or the high cost of fluorocarbonated polymers or tapes such as metal-plastic laminate tapes which are often difficult to apply in addition to characteristically lessening the flexibility of the hose as well as having seams which, if not sealed, provide an entrance-way for moisture through the core tube and into the fluid being conveyed through the hose.

The present invention provides a flexible hose for use in the conveyance of fluids having a barrier for preventing moisture from contaminating the fluid, said hose having a composite wall comprising a first layer made from a thermoplastic polyethylene material and a further layer surrounding said first layer, said further layer being made from a thermoplastic rubber material with said polyethylene layer providing the barrier against penetration of the moisture through the composite wall into the fluid.

The present invention also provides a flexible reinforced hose for use in the conveyance of fluids having a barrier for preventing moisture from contaminating the fluid, said hose having a flexible composite core tube having at least one layer of reinforcement material disposed thereabout, said core tube having a composite wall comprising a first layer made from a thermoplastic polyethylene material and a further layer surrounding said first layer, said further layer being made from a thermoplastic rubber material, with said polyethylene layer providing the barrier against penetration of the moisture through the composite core tube wall into the fluid.

The present invention still further provides a flexible reinforced hose for use in the conveyance of fluids having a barrier for preventing moisture from contaminating the fluid, said hose comprising a flexible core tube having at least one layer of reinforcement material disposed thereabout, said core tube having a composite wall comprising a first layer made from an extruded thermoplastic polyethylene material that is melt fused to a further layer of an extruded thermoplastic rubber material extruded about said first layer, with said polyethylene layer providing the barrier against penetration of the moisture through the composite core tube wall into the fluid.

Specific embodiments of the present invention will now be described by way of example and not by way of limitation with reference to the accompanying drawings in which Figure 1 is a partially broken away side elevation of a hose of the invention; and Figure 2 is a partially broken away side elevation of another hose of the invention.

With reference to the accompanying drawings and first to Figure 1, hose 11 has a composite core tube 1 comprised of an inner annular shaped layer 2 surrounded by outer annular shaped layer 3. A layer of reinforcement material 4 is disposed about core tube 1 and an outer annular shaped protection jacket S 5is disposed about reinforcement layer 4.

Reinforcement material 4 may be any reinforce ment material that is able to provide the strength and other properties desired for hose 11. Reinforce ment material 4 may be in the form of metal wire or it may be in the form of synthetic fibers made from aliphatic or aromatic nylon, polyethylene terephtha late ester or the like or combinations thereof.

Although shown in the form of a braid in Figure 1, it is to be understood that any suitable manner of disposing one or more layers of reinforcement about core tube 1 such as the oppositely helically wound strands shown in Figure 2 may be used.

Inner layer 2 of core tube 1 is made from a thermoplastic polyethylene and outer layer 3 of core tube 1 is made from a thermoplastic rubber. Prefer ably the polyethylene material forming layer 2 is a linear polyethylene in which parallelism between adjacent carbon chains is highly controlled as is commonly known to those ordinarily skilled in the art.

Variations available in the selection of the density of the particular polyethylene to make inner layer 2 can be used to advantage for tailoring the hose for a particular application. Generally polyethylene is characterised as having low, intermediate and high density. Typically low density polyethylene has a density of from about .915 to about .930 gm/cc; intermediate density polyethylene has a density of from about .930 to about 945 gm/cc and high density polyethylene has a density of from about .945 to about .965 gm/cc. Generally the stiffness of a polyethylene increases as the density increases due to what is believed to be closer packing of the carbon chains as the density increases.Thus one may select a a low density polyethylene where it is desired to impart greater flexibility to the hose or an intermedi ate or high density polyethylene where it is desired to decrease the flexibility such as in the case of sewer hose when the hose is pushed through sewers and may tend to fold or buckle in the event the hose is too flexible. An example of a linear low density polyethylene found to be of advantage for making layer 2 is sold by Union Carbide Corporation under the trade numbers GRSN 7-441. Polyethylene, parti cularly linear polyethylene, when used to make inner layer 2 has been found to provide an excellent barrier against moisture penetration through core tube 1 into the fluid being conveyed by the hose of the invention as well as having the density range 5 seiectivity ability previously described.

Outer layer 3 of the core tube 1 is made from a thermoplastic rubber. An example of a thermoplastic rubber found to be of advantage for making the core tube of the hose of the invention is sold as trade number 2103 under the trademark "Kraton" by Shell Chemical Company. Kraton 2103 is believed to be a styrene-butadiene-styrene block copolymer.

Although polyethylene has been notoriously diffi cult to bond to, it has been surprisingly found that when outer layer 3 of a thermoplastic rubber such as Kraton 2103 is coextruded in heated form in conjunction with inner layer 2 of polyethylene, the two melt fuse together to form a strong bond that is of advantage in the performance of the hose.

The flexibility of core tube 1 is not only controllable by the selection of the density of inner polyethylene layer 2 but also by the relative thickness of layer 2 with respect to layer 3. Thermoplastic rubber is considerably more flexible than polyethylene and thus the greater the thickness of layer 3 relative to layer 2 the greater the flexibility and vice versa. The bore through core tube 1 of the hose 11 may typically have an inner hose diameter of about 3/16 inch to about 1.5 inches.A particular construction found to combine attractive flexibility in combination with providing a highly effective barrier to the penetration or moisture into the fluid being conveyed by the hose is where (for an inner hose diameter of approximately one inch) the inner polyethylene layer 2 has a thickness of about .065 inch and the outer layer thermoplastic rubber layer 3 has a thickness of about .007 inch.

Hose 12 of Figure 2 has a composite core tube 1 having an inner polyethylene layer 2 and an outer thermoplastic rubber layer 3 previously described with respect to hose 11 of Figure 1. Core tube 1 has oppositely helically wound reinforcement layers 7 and 8 disposed about core tube 1 as shown in Figure 2. An adhesive layer 6 is disposed between the outer surface of layer 3 and reinforcement layer 7 and bonds them together. An adhesive layer 9 is disposed between and bonds reinforcement layers 7 and 8 together and an adhesive layer 10 is disposed between and bonds reinforcement layer 8 to protective jacket 5.

Hose 12 is illustrative of the fact that more than one reinforcement layer made from materials or combinations of materials previously described may be used depending upon the nature of the particular hose of the invention being constructed and that one or more of such layers of reinforcement may be bonded together by a suitable adhesive when such is desired. Hose 12 is also illustrative of the fact that protective jacket 5 may be bonded to the outermost layer of reinforcement of the hose where such is desired.

It is to be noted that the composite core tube of the hose 11 or 12 may itself be used as a hose of the invention devoid of any reinforcement layers where the particular application for which the hose is to be used does not require the strength provided by the reinforcement layers.

Although in some applications an outer protective jacket may not be required over the outermost reinforcement layer of the hose, in most cases it is preferred to use an outer protective jacket such as jacket 5 to protect the reinforcement from damage.

Jacket 5 may be made from any suitable material or wrapping that imparts the degree of protection desired. Commonly protective jacket 5 is made from a rubber, nylon or polyurethane material having the flexibility, strength and abrasion resistance desired for a particular application.

One of the advantages found in providing a thermoplastic rubber outer layer 3 about inner polyethylene layer 2 is that whereas it would have been extremely difficult to bond reinforcement layer 7 to polyethylene layer 3, layer 7 can be bonded to thermoplastic rubber layer 3 in a relatively simple manner by means of a suitable adhesive such as formed by solvating an amount of the thermoplastic rubber in a suitable solvent to form a cement or by making an adhesive in situ by solvating the surface of layer 3 by means of a suitably selected solvent so that the strands of reinforcement material become embedded in the outer surface of layer 3 due to the softening of the outer surface of layer 3 caused by the solvent.Although other solvents may also be suitable, it has been found that eithertrichloro ethylene or methylene chloride is an effective solvent when layer 3 is made from a styrene-butadienestyrene block copolymer compound such as Kraton 2103 sold by Shell Chemical Company.

Providing a composite core tube in the hose having an inner layer in the form of a polyethylene material and an outer layer in the form of a thermoplastic rubber provides a simple and economical way of providing a barrier against penetration of moisture into the fluid being conveyed through the hose by means of the polyethylene layer while imparting an attractive flexibility to the hose by means of the thermoplastic rubber layer in addition to the surprising advantage that the polyethylene and thermoplastic rubber layers are able to be melt fused as well as enabling the reinforcement material closest to the core tube to be bonded thereto in a much simpler manner than would have been the case had the outer layer been made from the polyethylene material.

Claims

1. A flexible hose for use in the conveyance of fluids having a barrier for preventing moisture from contaminating the fluid, said hose having a composite wall comprising a first layer made from a thermoplastic polyethylene material and a further layer surrounding said first said layer, said further layer being made from a thermoplastic rubber material with said polyethylene layer providing the barrier against penetration of the moisture through the composite wall into the fluid.

2. A flexible reinforced hose for use in the conveyance of fluids having a barrier for preventing moisture from contaminating the fluid, said hose having a flexible composite core tube having at least one layer of reinforcement material disposed thereabout, said core tube having a composite wall comprising a first layer made from a thermoplastic polyethylene material and a further layer surrounding said first layer, said further layer being made from a thermoplastic rubber material, with said polyethylene layer providing the barrier against penetration of the moisture through the composite core tube wall into the fluid.

3. A flexible reinforced hose for use in the conveyance of fluids having a barrier for preventing moisture from contaminating the fluid, said hose comprising a flexible core tube having at least one layer of reinforcement material disposed thereabout, said core tube having a composite wall comprising a first layer made from an extruded thermoplastic polyethylene material that is melt fused to a further layer of an extruded thermoplastic rubber material extruded about said first layer, with said polyethylene layer providing the barrier against penetration of the moisture through the composite core tube wall into the fluid.

4. The hose of claim 2 or 3 including a protective jacket disposed about the reinforcement material.

5. The hose of claim 1 or 2 wherein the first and said further layer are melt fused together.

6. The hose of claim 2 or 3 wherein the reinforcement material is a fibrous reinforcement material.

7. The hose of claim 2 or 3 wherein said further layer is bonded to the layer of reinforcement material adjacent thereto.

8. The hose of claim 4 wherein the jacket is bonded to the layer of reinforcement material adjacent thereto.

9. The hose of claim 1, 2 or 3 wherein the thermoplastic rubber material is a styrenebutadiene-styrene block copolymer compound.

10. The hose of claim 1,2 or 3 wherein the polyethylene is a linear low density polyethylene having a density from about .915 to about .930 gms/cc.

11. The hose of claim 1,2 or 3 wherein the polyethylene is a linear intermediate density polyethylene having a density of from about .930 to about .945 gm/cc.

12. The hose of claim 1, 2 or 3 wherein the polyethylene is a linear high density polyethylene having a density of from about .945 to about .965 gm/cc.

13. The hose of claim 3 including a protective jacket disposed about the reinforcement material.

14. A flexible hose for use in the conveyance of fluids substantially as hereinbefore described with reference to, and as shown in, Figure 1 or Figure 2 of the accompanying drawings.