CA1192850A

CA1192850A - Flexible hose having moisture barrier

Info

Publication number: CA1192850A
Application number: CA000424314A
Authority: CA
Inventors: Daniel Polasky
Original assignee: Eaton Corp
Current assignee: Eaton Corp
Priority date: 1982-04-01
Filing date: 1983-03-23
Publication date: 1985-09-03
Also published as: AU1310983A; AU551389B2; DE3311877A1; JPS58203280A; GB8307943D0; GB2117482A; GB2117482B

Abstract

ABSTRACT OF THE DISCLOSURE

Disclosed is flexible tubing and reinforced hose having a composite core tube that is provided with a composite wall comprising an inner annular layer of thermoplastic polyethylene and an outer annular layer of thermoplastic rubber material that is preferably melt fused to the inner layer. The polyethylene layer provides a barrier against penetration of moisture into fluid being conveyed through the tubing or hose 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 to be secured tightly to the polyethylene inner layer by being bonded to the rubber outer layer which, if absent, would have otherwise been extremely difficult if not impossible to achieve using conventional manufacturing techniques.

Description

2~

FLEXIE~LE ~OSE
HAVING MOISTURE BARRIER

INTRODUCTION

Thi~ inventi¢n relates generally to a flexible reinforced hose for use in the conve~ance of fluids and more particularl~ to a flexible reinforced hose having a composite core tub~ that is adapted to provide a barrier to the penetration of moisture into the ~luid.

BA~KGROUND OF THE INVENTION

Flexible reinforced hose has been used for many years to convey a variety of fluids from on~ point to another. In some instances the fluid belng conveyed throu~h the hose is of a typ~ that would be adversely affected in the event that it wa~ exposed to moisture such as water vapor duri~ s presence in the hose.
Unfortunately, excep~ing for certain costly and difficult to proeess fluorinated polymers, the type of materials commonly used to make hoses such as natural and syn~hetic rubber, nylon, polyester and polyu~e~hane 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 contaminating the fluid being conveyed through the hose~

Some hose construs~tions have become more sophisticated by the use o core tubes having multiple l~yers rather than a single layer as was common practice in the past. An examp.l.e of a multiple layered core tube in a hose construction can be found in United Sta~es Patent 2,564,602 in which l:he core tube has an inner layer made from a relatively so~t rubber and an outer layer made from a harder poJ.ymeric material such as nylon, polyamide chloride or polyethy~ene for protecting the inner rubber layer from damage by metal braid reinorcement 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 featur~s a polyurethane layer melt fused to either or both the inner and outer surface of the polyvinyl chloride layer to improve the streng~h of the polyvinyl chloride layer~ An example of a composite tube having multiple layers is found in United States Paten~

3,561,493 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 toyether are made.

Although polyolefin polymers such as polyethylene are considerably lower in cost than fluorocarbonated polymers and are known to provide a good barri~r against moisture penetration~ their use as a core tube in hose constructions ha~ heretofor been limited due to their greater inherent stiffness compared 3b to more conventional hose materials and ~o their ~Z~5~t tendency to kink in tube form. Additionally, it has not been satisfactorily demons~r.ated that polyolefin polymers in tube form can be suitably bonded to en~ompassing reinforcement material which bonding wvuld reduc~ their tendency to kink. Polymer compositions commonly used in hose constructions such as plasticized nylon, neoprene and NBR cont:ain additives to improve ~lexibility, processi~ and other properties which over a period of time are abl~ to migrate into and contaminate the ~luid being conveyed th~ough 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 ~he prior-art hose, whether having a composite core ~ube or no~, have heretofor add~essed the problem 3~ preventing moisture from penetrating through the core tube and co~tamina~ing the fluid without encountering the problem of flexibility and bonding associated with polyolefin materials or the high cost of fluoroc~rbonated polymers or tapes such as metal-plastic laminate tapes which are often difficult to apply in addition to characteristically lessening ~he flexibility of th~ hose as well as having seams which, if not sealed, provide an entrance-way for moisture through the 25 . core tube and into the fluid bein~ conveyed through the hose.

SU~lARY OF THE INVENTION

Accordingly, it is an object of this invention to provide a flexible reinforced hose that is able to prevent moisture from contaminating or otherwise affecting fluid being conveyed through the hose by means of a moisture barrier tha~ is easily and economically incorporated as a part of the hose core tube during the manllfacturing process.

It is another object of this invention to provide a flexibl~ reinforced hose that is provided with a moisture barrier as an inner layer o~ the hvse core tube as a means o~ preventing moisture from contaminating or otherwise affecting fluid being conveyed through the hose, that is economical to apply, and that, in conjunction with another outer layer of the core tube, does not adversely affect the flexibility of the hose~

It is a fur~.her object of this invention to provide a flexible reinforced hose which will not significantly contamina~e the fluid being conveyed.
.

I~ is yet another object of thi~ invention to provide a flexible reinforced hose that is able to incorporate a layer of polyethylene as part of the core tube of the hose as a barrier against penetration of moisture into fluid being conveyed by the hose while maintaining a high level of flexibility in the hose in addition to enabling the core tube to be bonded to the hose reinforcement material.

~ 5 --BRIEF DESCRIPTION OF THE DRAWINGS

FIGURE 1 is a partially broken away .side elevation of an embodiment of the hose of the invention;
and FIGURE 2 is a parl-.ially broken away side elevation of anothex embod:iment of the hose of the invention.

DETAILED DESCRIPTION OF PREFERR~D EMBODIMENTS

FIGURE 1 shows an embodiment of the invention in the form of hose 11~ 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 abou.t core tube 1 and an outer annular shaped protection jacket 5 is disposPd about reinforcement layer 4.

Rei~forcement material 4 may be any reinforcement material that ls able to provide the strength and other properties desired for hose 11.
Reinforcement material 4 may be in the form of metal wire or it may be in the form of synthetic fibers made rom aliphatic or aromatic nylon, polyethylene terephathalate ester or the like or combinations thereof. Althouyh shown in the form of a braid in FIGU~E 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 is considered to be within the scope of the invention.

Inner layer 2 of core tube 1 is made from a ~hermoplastic polyethylene and outer layer 2 of co~e tube 1 is made from a thermoplastic rubber. Pre~erably the polyethylene material forming layer 2 is a linear polyethylene in which paral:Lelism 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 o the particular polyethylene to make inner laye~ 2 can be used to advantage ~or tailoring the hose for a particular application. Generally polyethylene is characterised as having low, intermediate and high density. Typically low density polyethylene has a d~nsity of from about .9lS 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 ym/cc. Generally the stiffne~s of a polyethylene increases as the de~sity increases due to what is believed to be closer packing of the carbon chains as th~ density increases. Thus one may sele~t a low density polyethylene where it is desired to impart greater flexibility to the hose or an intermediate 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 m~y tend to fold or buckle in the event the hose is too flexibleO An example of a linear low density polyethyl~ne found to be o~ advantage ~or making layer 2 is sold by Union Carbide Corporation under ~he trade numbers GRSN 7-441. Polyethylene, particularly linear polyethylerle, when used ~o make inner layer 2 has been found to provide an excel~ent barrier again~t moisture penetration through core tube 1 into the fluid heing conveyed by the hose oE the invention as well as haviny the density range selectivity ability previously de sc r i bed ~

Outer layer 3 o~ core tube 1 is made f rom 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 difficult to bond to, it has been suprisingly found that when ou~er 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 mel~ fuse together to form a strong bond that is of advantage in the performance of ~he hose~

The flexibility of core tube l is not only 2S 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. Thermoplas~ic rubber i5 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 throuyh core tube 1 of the hose made in accordance with the invention typically have an inner hose diameter of about 3/16 inch to about l.5 inches. A
particular construction ound to combine attractive flexibility in combination with providiny a highly effeckive barrier to the penetration of moisture into the fluid being conveyed by the hose is where (for an inner hose diameter of approximately one inoh) 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.

FIGURE ~ show~ an embodiment of the invention in the form of hose 12. Hose 12 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. Coxe tube 1 has oppositely helically wound reinforcament layers 7 and 8 20 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 reinforc@ment layers 7 and 8 togPther and an adhesive layer 10 is disposed between and bonds reinforcement layer 8 to protective jacket 5.

Elose 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 o such layers of reinforcemell may be bonded together by a suitabLe adhegive when such iS desired. Hose 12 is al50 S illustrative of the fact that protective ja~ket 5 may be bonded to the outerm~st layer of reinforcement of the hose of the invention where such is desired.

It is to be noted that the composite core tube of the hose of the invention may itself be used as a tube devoid of any reinforcement layers where the particular application for which the tube 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 of the invention, in mos~ cases it is preferred to use an outer protective jacket such as jacket 5 to protect the rein~orcement f rom dama~e. Jacket 5 may be made from any suitable material or wrapping that impar~s the degree of protec~ion desired. Commonly protective jacket 5 i5 made from 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 poyethylene layer 3, layer 7 can be bonded to thermoplastic rubber layer 3 in a relatively simple manner by mean~ of a suitable adhesive such a~ formed by solvating an amount of the thermopLastic rubber in a suitabLe solvent to form a cement or by making an adhe~ive i.n situ by ~olvating the surface o~ 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 o layer 3 caused by the solvent. Although other solvents may also be suitable, it has been found that either ~richloro ethylene or methylene chloride is an ef~ective solvent when layer 3 is made from a styrene-butadiene-styrene block copolymer compound such as Kraton 2103 sold by Shell Chemical Company.

Providing a composite core tube in the hose of the invention having an inner layer in the form of a polyethylene material and an outer layer in the form of a thermoplastic rubber provide~ 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 ~ttractive flexibility to tha hose by means of the thermoplastic rubber layer in addition to the suprisin~
2S advantage that the polyethylene and thermoplastic rubber layers are abLe to be melt fused together to provida greater integrity to the core tube as well as enabling the rein~orcement 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

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY OR
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A flexible reinforced hose for use in the conveyance of fluids having a barrier for preventing moisture from contamina-ting 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 an inner layer made from an extruded thermoplastic polyethylene material that is melt fused to an outer layer of an extruded thermoplastic rubber material, with said inner polyethylene layer providing the barrier against penetration of the moisture through the composite core tube wall into the fluid.

2. The hose of Claim 1 including a protective jacket disposed about the reinforcement material.

3. The hose of Claim 1 wherein the reinforcement material is a fibrous reinforcement material.

4. The hose of Claim 1 wherein the core tube outer layer is bonded to the layer of reinforcement material adjacent thereto.

5. The hose of Claim 2 wherein the jacket is bonded to the layer of reinforcement material adjacent thereto.

6. A flexible tube for use in the conveyance of fluids having a barrier for preventing moisture from contaminating the fluid, said tube having a composite wall comprising an extruded inner layer made from a thermoplastic polyethylene material and an extruded outer layer made from a thermoplastic rubber material, the inner and outer layers being melt fused together, with said inner polyethylene layer providing the barrier against penetration of the moisture through the composite core tube wall into the fluid.

7, The product of Claims 1 or 6 wherein the thermoplastic rubber material is a styrene-butadiene-styrene block copolymer compound.

8. The product of Claims 1 or 6 wherein the polyethylene is a linear low density polyethylene having a density from about .915 to about .930 gms/cc.

9. The product of Claims 1 or 6 wherein the polyethylene is a linear intermediate density polyethylene having a density of from about .930 to about .945 gm/cc.

10. The product of Claims 1 or 6 wherein the polyethylene is a linear high density polyethylene having a density of from about .945 to about .965 gm/cc.