CA2078121C - Braided product and method of making same - Google Patents

Abstract

An expandable braided product having greatly reduced tendency to splay at its ends when cut is provided by coating the braided product (10) with a thin layer of elastomeric material which provides the desired anti-splaying property, while retaining the expandable characteristic whereby the product expands laterally when compressed longitudinally and when released returns to its original size and shape.

Description

Wosl/l4o34 pcr/us9l/ol3o3 2 ~ 2 ~

1 BRAIDED PRODUCT ~ND METHOD OF MAKING SAME

Field of the Invention This invention relates to monofilamellt braided product and to methods for making same. It relate~ more particularly to braided product made up of monofilaments, typically of a resilient engineered plastic material and typically (but not necessarily) in the form of a tubular ::
sleeve. . .

Back~round of the Invention One known form of braided product is the ExpandoTM
selfwfitting protective oversleeve made by Bentley-Harris Manufacturing Co. of ~ionville, Pennsylvania. This tubular sleeve is expandable in that, when the ends are pushed toward each other it expands in diameter, and when they are released 15 it returns to its original shape and size. This enables it to be pulled or pushed over objects of different diameters, including diameters greater than the unstressed or "rest"
diameter o~ the sleeve, and also enables it to accommodate expansion, bending and twistiny of hoses or wires which may 20 run through it. This expandable ~raided product also e~hibits a l'spring-back" or "memory" characteristic, whereby it tends to return to its rest diameter when released from longitud;n~1 forces. Such expandable braided sleeving has been widely used, for example ko protect, and/or dxess, 25 wiring haxnesses and hose assemblies.

WO91/14034 pcr/us9l/o13o3 ~37~% l l One difflculty with the typical braided product of ~ :
the expandable type is that when the braid is cut in an ordinary manner, as by scissors, the ends of the braid will tend to unravel or splay~ the braiding coming apart for a substantial distance back from the cut ends. This is particularly troublesome when an end of a braided sleeve must be forced over a large-diameter object, causing the monofilaments to splay and therefore no longer provide the ~ .
desired type of tight fit on the smaller-diameter contents of ~:
the tubular covering; in addition such splaying is cosmetically very undesirable.
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There axe currently three principal ways in which this problem has been addressed, as follows:
(l) Coat the braided Droduct with a continuous coating. This eliminates the splaying, but also restricts the expandability of the braid and therefore its ability to slide overl or wrap around, an object with full conformity to variable cross-section of the object. Such a construction also prevent~ one from "breaking out" a branching wire from the interior of braided tubing, as is sometimes desirable.
(2) Heat-set the braided product. ~ieating the completed product will put a slight set into the hraid, bu~ ~:
with even slight mechanical expansion the ends will unbraid and splay out again. .

(3) Cut the braid with a hot kni~e or wire. With :.
most plastic braidings, the sleeve can be cut through with a -.
hot knife or wire, thereby fusing the monofilaments to each other to prevent the braid from fraying or unraveling.
However, ~uch end treatment will fix the diameter at that set -~
by the fusing of the end of the tubular braid, and thereby " ' .

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l prevent the braid from expanding readily to receive a large object. Further, this method requires use of special hot melt devices to provide such cutting of the braid, and therefore is not useful for field installations of the sleeve where no such special tools are a~ailable.

Accordingly, it is an object of the present invention to provide a new braided product and method of making it, which minimize such fraying while retaining the.
natural expansion and contraction characteristics of the expan~able type of braided product.

It is also an ohject o~ the invention to provide such method and apparatu~ in which the treatment providing .:
the above described advantageous characteristics is readily and inexpensively performed, and in which the user can cut the resultant braided product to the desired length without having to use any special cutting or bonding tools.

Summary of the Invention These and other objects of the invention are achieved by the provision of a monofilament braided product in which the braided product is at least partly coated with an adherent, pre~erably elastomeric, material extending form at least some over-weave mono~ilaments to their assoc.iated underweave monofilaments at their respective cross-overs, permitting the mono~ilaments to pivot with respect to each ~5 other as required to retain the desired expandable characteristics, while preventing splaying. The coating is .

WO9]/lqO34 P~T/US91/01303 2~7~121 l preferably of an elastomeric material, ancl preferably does not completely cover the openings between the monofilaments.

The coating is preferably applied by passing the braid continuously through a liquid bath containing the coating material in flowable form, and then solidifyiny the coating in position on the braided product. The viscoc;ity of the liquid of the coating is such that it provides enough material in the proper places to fix the monofilaments against end splaying, while retaining the ability of the.
lO filaments to pivot with respect to each other, and the ~ :
consequent ability of the sleeve to expand and shrink in cr~ss-sectional size. If the coating does initially extend ::
across the openings between the monofilaments, it is preferably such as to break upon longitudinal compression of 15 the braided material, although with a suf~iciently compliant elastomeric material thi~ is not always necessary. . -In this manner there is provided a braided product ::
and method of making it which prevent splaying of the end of ::
the braid without materially adversely affecting the 20 expandable characteristics oP the braid. ;~:

Brief Description of Fiqures :' , .
These and other objects of the inv~ntion will be -:
understood from a consideration of the fol~owing detailed description taken in connection with the accompanyiny 25 drawings, in which: :
Figure 1 is a side view of a section of expandable tubular product which has been cut by an ordinary pair of ' ., . ~ ,, . '. ' ,. , . ','.'' ,'''"'''''''', ','.'''"' ~; ' '''.'; ' ~ ' WO91/14034 PCT/US91/0]303 2 ~

1 scissors, and mechanically expanded at the cut end, and which exhibits substantial splaying at its end;
Figure 2 is a side view of a section of expandable braided product made in accordance with the invention, cu~ at its end with an ordinary pair of scissors and then subjected ~to a similar expanding procedure.
Figure 3 is an enlarged fragmentary ~iew of the exterior of the braided product of Fig~ 2;
Figure 4 is a cross-sectional view taken on lines 10 4-4 of ~igure 3, showing the braided product of the invention a~ter the coating has been formed therein;
Figure 5 is a cross-sectional view taken along lines 5-5 of Fig. 3; and : :
Figure 6 is a cross-sectional view like Figure 5, 15 but illustrating the condition in which a ~reak exists in the coating near each cross-over of the braid.

Detailed Descri~tion o~ Specific Embodiments Referring now to the embodiment of the invent.ion shown in the drawings by way of example only, and without 20 thereby limiting the scope of the invention, Figure 1 shows a section of expanded, braided tubular sleeving 8, constructed in accordance with the prior art and exhibiting undesired splaying of the monofilaments at its end 9. Figure 2 shows a l~ngth of exp~ndable, braided, tubular sleeving 10 in 25 accordance with the present emhodiment of the invention. It is made up of monofilaments such as 11, 12, 13, 14 in a simple single-strand two-over, two--under braid pattern. Each mono~ilament in this example is o~ engineered plastic, for example nylon or poly~ster, and is substantially rectangular W~91/~034 PCT/U~91/0130~

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l in cross-section. The monofilaments are covered with an adherent elastomeric coating 16. In some cases, particularly after expansion and contraction of the braid by pulling and pushing of its ends, the coating may contain a break where one monofila~ent crosses another, as indicated by the break lines such as 20, 21 in Fig. 6.

In this preferred embodiment of the invention the coating does not decreas~ substantially the areas of the openings such as 30, 3l between the monofilaments, so that l0 space remains for the filamerlts to pivot at the cross overs, :.
one with respect to its adjacent neighbor, during expansion and contraction of the sleeve, according to the usual - -:
characteristic of such expandable braids. The elastomeric :-coating tends to fix the positions of the cross-overs, but 15 being elastomeric, it permits the necessary pivoting of the monofilaments with respect to each other. ~his fixing action -~ .
of the elastomeric material prevents the ends from splaying, as is important for the reasons pointed out above. The retention of the openings such as 30, 31 also permits a wire 20 or the like to be ex~racted and passed outwardly ~'rom the ~leeve if so desired.
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While there may be a variety of methods by which the coating may be applied, it is preferred to accomplish it by passing a continuous sleeve of the braided material ~ :
25 through a bath of the coating material and then drying it in an oven.

One presently-preferred example of the improved ~raided product and of a method for making it, is as follows:
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l A continuous, expandable braided tube of about 9.5x10-3 meters rest diameter is made in conventional manner fxom 48 monofilamPnts of 100 denier nylon, each monofilament about 30 mils wide and about 10 mils in thic~nessJ the S braided tubing is typically coiled on a spool in long lengths, e.g. 609.6 meters lengths. The tubing ~rom the spool is then run lengthwise downward into and through a bath o~ the coating material, continuing upwardly therefrom through a hot-air oven typically operating at about 150~C.

The liquid coating material may be resorcinol formaldehyde, with a viscosity of 15,000 centipoise~ or less so thak it will coat the monofilaments in the braid without closing the openings betw~en them. Preferably the tubing is subjected to stretching while passing through the bath, and 15 until drying of the coating is complete.

The resultant braided tuhin~ can be cut to length with ordil~ary scissors, and will then exhibit minimal tendency toward splaying. Nevertheles~, when longitudinally compressed it will increase its diameter and when stretched 20 it will regain its original cliameter, and it will also exhibit memory in that, when unstressed, it tends to return to the diameter and length it had before compression.

In general, the invention is applicable to a wide . ::
variety o~ sizes, shapes and materials of braids and of 2S monofilaments, including monofilaments of round cross- -:
section; it is also o~ wide applicability with re~pect to the number of monofilaments in the braid. While many important ~:

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1 applications of the invention involve a tubular braid, the invention is also useful in making flat, mat-like expandable braid products. Also, while the coating materials is preferably ela~itomeric, at least some of the advantages o~ :
the invention may be realized by using a non-elastomeric material for the coating which does not bond the filaments rigidly together, but instead fractures upon compression and/
or stretching of the braid, leaving low walls of coating material on each side of each monofilament at each cross-over 10 to provide a positioning channel, or at least a high-friction surface, which resists the type of displacement of the monofilaments which occurs during splaying. A similar effect exists in some cases when an elastomeric ~aterial is used which fractures during stretching 2nd/or compression. Other 15 coating procedures may also be used, so long as they do not result in such a thick, pervasive coating that the monofilaments cannot pivot, each with respect to its neighbor, as is required to exhibit the desired expandable characteristic.

While the invention has been described with particular reference to specific embodiments thereo~ in the interest of complete definiteness, it may be embodied in a variety of forms diverse from thos~ specifically shown and described, without departing from the spirit and scope of the :~
25 invention. ~ -:'. ~" .
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Claims (15)

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

1. A braided product which, when compressed along a first direction, expands along a second direction transverse to said first direction and when released tends to return to its original configuration, comprising:
a plurality of over-and-under mutually-crossing braided monofilaments forming with each other a plurality of monofilament cross-overs, with apertures extending through said braided product between said monofilaments; and a thin deposit of an elastomeric material extending over the exterior surfaces of said monofilaments at each of said cross-overs but leaving said apertures at least partially open, said elastomeric material differing from the material of said monofilaments and serving as a resilient adhesive for holding said monofilaments against mutual lateral motion while permitting them to pivot with respect to each other at said cross-overs.

2. The braided product of claim 1, wherein said elastomeric material is selected form the group consisting of resorcinol formaldehyde and acrylic latex.

3. The braided product of claim 1, wherein said product is a braided sleeve.

4. The braided product of claim 1, wherein said monofilaments are of engineered plastic.

5. The braided product of claim 1, wherein said monofilaments are selected from the group consisting of nylon and polyester.

6. The braided product of claim 1, wherein said product is a sleeve, said monofilaments are of a material selected from the group consisting of nylon and polyester, and said elastomeric material is selected from the group consisting of resorcinol formaldehyde and acrylic latex.

7. A method of treating a monofilament expandable braided product to reduce its tendency to splay at its ends while retaining its expandable properties, comprising:
applying a thin deposit of adherent solid material on an exterior surface of said monofilaments of said braid to hold them in their proper relative positions and thereby minimize the tendency toward splaying at the ends of said braid, said deposit leaving at least partially open apertures between cross-overs of said monofilaments to permit said monofilaments to pivot with respect to each other at their cross-overs so as to retain the expandable characteristics of said braided product.

8. The method of claim 7, wherein said material is elastomeric.

9. The method of claim 8, wherein said material is selected from the group consisting of resorcinol formaldehyde and acrylic latex.

10. The method of claim 7, wherein said deposit is from about 1 to about 20 mils in thickness.

11. The method of claim 7, wherein the applying of said deposit comprises passing said braid through a bath of said material in its flowable form, and thereafter allowing said material to solidify on said braid.

12. The method of claim 11, wherein said material of flowable form has a viscosity not substantially greater than 15,000 centipoises.

13. The method of claim 7, wherein said forming of said deposit comprises coating substantially all exposed surfaces of said monofilaments with said material in flowable form without filling the opening between said monofilaments.

14. The method of claim 7, comprising applying said deposit over said monofilaments and the openings between them, and thereafter compressing said braided product to break open said deposit in the regions where it covers said openings.

15. The braided product made by a method as claimed in any of claims 7, 8, 9, 10, 11, 12, 13 or 14.