GB2338494A

GB2338494A - Under-cast padding

Info

Publication number: GB2338494A
Application number: GB9913316A
Authority: GB
Inventors: Colin Raymond Bradford; Michael Armitage; Christine Forsyth
Original assignee: Smith and Nephew PLC; Smith and Nephew Inc
Current assignee: Smith and Nephew PLC; Smith and Nephew Inc
Priority date: 1998-06-20
Filing date: 1999-06-09
Publication date: 1999-12-22
Also published as: GB9913316D0; GB9813247D0

Abstract

A spirally wound, nonwoven, tubular under-cast padding comprising an elastic component 5 sandwiched between overlapping windings 6. The windings may be joined by needling.

Description

1 2338494 UNDERCAST PADDING The present invention relates to a tubular

fabric product, which advantageously is a tubular medical padding, and a process for the manufacture thereof.

Treatment of bone deformities such as bone fractures usually involves immobilisation of a portion of the body, for example within a rigid cast made of Plaster of Pads, polymers or synthetic resins.

Such rigid casts, which often remain on the body for a month or two can cause discomfort and trauma to the patient. Trauma can be caused by the chaffing of those parts of the body, such as bony protuberances, which are placed under pressure by the cast. Such chaffing or pressure may lead to ulceration of the skin or tissue overlying a protuberance. To alleviate this problem R is usual to apply an underpadding to the body portion prior to forming the cast to act as a cushion between the cast and body. The underpadding commonly used for this purpose is a strip of fibrous wadding which can be wrapped around the body portion or over a tube of extensible knitted stockinette previously applied over a body extremity onto the body portion.

A disadvantage of employing fibrous bandages in this way is that they have to be wrapped around the limb in multiple layers to provide sufficient padding. This is considered time consuming and, if not expertly done, can lead to areas not having sufficient cushioning. Additionally, prior to applying the undercast padding, a lightweight knitted fabric or stockinette is usually put on the limb first. This adds time and cost to the treatment and the product can also be wasted due to roll ends having to be discarded.

2 Some unitary undercast products are also available. These tend, however, to comprise at least two discrete layers of material laminated together and have the disadvantage that they can delaminate.

The present invention avoids the problems associated with prior art products by providing a.novel unitary tubular product and a process for the manufacture thereof.

The tubular product of the invention comprises at least one spirally wound nonwoven component and a spirally wound elastic component, wherein consecutive windings of said at least one nonwoven component overlap one another and each winding of said elastic component is sandwiched between adjacent overlapping windings of the at least one nonwoven component.

A process for the manufacture of a tubular product is also disclosed, wherein an elastic component and at least one nonwoven component are spirally wrapped around a stationary mandrel such that consecutive windings of the at least one nonwoven component overlap each other and each winding of said elastic component is sandwiched between adjacent overlapping windings of said at least one nonwoven component.

(it should be mentioned that the term "spirally wound" is used in the generally known and understood sense meaning "helically As will be explained in more detail with reference to the 30drawings, the thickness of the final product and the evenness of the internal and external surfaces of said product are determined by the 3 number of overlapping windings h comprises. As will be readily appreciated, apart from at the very beginning or very end of the winding process, where the layers are building up upon one another, the product has a uniform thickness determined by the number of said overlapping layers. The number of overlapping windings is determined by the speed with which the product is drawn off the mandrel - a high speed results in little overlap and a correspondingly stepped surface upon which the individual windings are clearly visible, a 1 ower speed results in a higher degree of overlap. With a significant degree of overlap, the individual windings become less distinguishable from one another and the surface appears smoother to the eye. The number of windings employed is typically between three and ten. Between three and six overlapping windings are preferred.

Advantageously, the windings of the nonwoven component are interconnected. This may be achieved by needling or thermobonding them together. It is strongly preferred not to use adhesives for this purpose. The degree of interconnection of the fibres is regulated so as not to interfere with the elastic properties bestowed by the elastic component. Plainly, if a fibrous product is needled sufficiently, it takes on an overly high degree of rigidity. This is not desired. In the event that the fibres are thermobonded, then up to 20% weight of the nonwoven fibres will be the thermobonding fibres, to give the required inter-fibre connection, but not limit the ability to stretch.

The nonwoven raw material fed to the process advantageously has a weight range of 20-1 00g1M2. The nonwoven fibres can be any fibres commonly used in the present field, but are preferably manufactured from viscose, polyester, a mixture thereof or cotton.

4 The fibres of the nonwoven advantageously have a staple length of at least 30mm.

The elastic component of the present product may comprise elastorneric yams made, for example, polyurethane (e.g. LYCIRATM) within a decitex range of 500 -1500. In this case, the yam wiindings may be spaced from 1 to 20mm from each other. Advantageously, the said windings are spaced from 3 to 12mm from each other. Altematively, the elastic component may comprise a polymeric foam, which advantageously has a thickness of between 1 and 4mm and is preferably made of polyurethane. A further alternative to the above materials is elastic netting. Advantageously, the netting may be made of polyurethane. A typical a spacing between the strands of the net is 2mm. The advantage of using netting is that it is elastically conformable over a whole surface rather than only specific parts of that surface. Finally, retention bandages may also be used as the elastic component. Suitable bandages for this purpose are EASIFIXTm and TENSOFIXTm, manufactured by Smith and Nephew Plc.

1. Preferably, the nonwoven component of the finished product makes up at least 50% of the total weight of the material. The product nonwoven ideally has a weight in the range 250 - 350 g1M2.

With reference, once again, to the inventive process, the nonwoven and the elastic components are wrapped together around a stationary mandrel. The elastic component can be fed in adjacent to the upper or the lower surface of the nonwoven. Said elastic component may also be located anywhere between the lateral portions of the (upper or lower) surface of the strip of nonwoven as it is fed in.

Depending upon the lateral position of the elastic component on the surface of the nonwoven, i.e. whether it is in the middle, nearer to one side or nearer the other side, the properties of the finished product can be altered in subtle ways. If, for example, the elastic component is nearer one side of the nonwoven as it is wound onto the mandrel, said elastic component will be located nearer the outside surface of the final product. Such a product has the advantage that it is highly conformable to an irregular surface, such as a limb. If, on the other hand, the elastic component is fed in nearer to the other side of the nonwoven component, the elastic component in the final product will be nearer the inside of the final product. Such a product has the characteristic that it is less conformable than the previously defined product, but provides better cushioning, because certain layers of the nonwoven are not compressed by the elastic.

A further advantage of the inventive process is that R is possible, in a single step, to manufacture a tubular product which has one nonwoven component on the inside surface, and a second, possibly quite distinct, nonwoven component on the outside surface. This is achieved by wrapping the two components side by side onto the stationary mandrel. The automatic result of this process is that one of the components forms the internal surface of the product, while the other forms the external surface of said product. The elastic component can be fed in such that it is sandwiched within the overlapping windings of either of the nonwoven components. The process has the advantage that the product can be tailored to meet different criteria: for example, a soft fleecy nonwoven can be used as the internal, skin-contacting layer, whereas a more durable 6 nonwoven can be employed as the outer layer which contacts the cast.

In a further embodiment of the inventive process, a plurality of different nonwoven materials may be wound side by side to give a tailor- made product with precisely determined characteristics, for example reducing softness combined with increasing stiffness across the wall thickness.

Reference is made to the figures of the application. It should, however, be noted that the figures are included by way of illustration only and are not intended to be limiting. In particular, while the elastic component (8) illustrated in figures 3A, 313 and 4 comprises a single elastic thread, R may, according to the invention comprise a plurality of such threads, a polymeric foam with elastic properties, elastic netting, stockinette or other elastic component. Furthermore, while in the examples of the figures the nonwoven is bonded by needling, other methods as defined herein may also be employed.

Fig.1A is a representation of a cross-section of tube-material according to the invention, wherein the elastic component has been added such that it is directly in the centre of the material thickness.

Fig. 1 B is a representation of a cross-section of tube-material according to the invention, wherein the elastic component has been added such that R is located towards one edge of the material thickness of the final product.

Fig.2 is a representation of the process of manufacture of the invention, showing nonwoven and a strand of elastic material being wrapped around a stationary mandrel (not shown) and needled.

7 Fig.3 is a further representation of the process of manufacture using a machine developed by the company Dilo GmbH.

Figs. 4A and 4B demonstrate the effect of the draw-off speed on the degree of winding overlap of the finished product.

Figs. 5A -5C illustrate the effect of the lateral position of introduction of the elastic component upon the position of said elastic component in the final product.

Figs. 6A and 6B illustrate the winding of two nonwoven components side by side onto a mandrel and the resulting final product.

There follows a more detailed discussion of the figures:

As shown in Fig.2, the invention causes both the nonwoven and the elastic component to be wrapped together in direction (10) directly on top of one another a strip of nonwoven (4), typically with a width of between 5 and 30 cm, and an elastic thread (5) are wrapped together onto a mandrel, such that consecutive strips overlap one another and sandwich the elastic thread (5) between succeeding windings (6) of nonwoven (the preceding windings are not shown in Fig.2). This arrangement is illustrated in Fig.1A, which shows the thread (5) arranged in the middle of the material thickness (t).

By altering the lateral position of introduction of the thread (5), it is possible to change its position within the final product. For example, by moving the position of introduction of the thread (5)

8 shown in Fig.2 to the right, it is possible to create the material shown in Fig. 1 B, in which the elastic thread (5) is near one external surface of the composite material. Were one, in contrast, to shift the position of introduction of the thread (5) shown in Fig.2 to the left, then a composite material would be created in which the elastic threads were nearer the other external surface of the material. With reference to Fig. 1A again, the position (x) of the elastic component within the thickness (t) of the wall of the tubular product is such that 0 < x < t. This process is also illustrated in Figs.5A - 5C: As can be seen in Fig.5A, when the thread is introduced on the left-hand side of the nonwoven strip, it is located near to the inner surface of the final product; when it is introduced close to the right hand side of the nonwoven strip, as shown in Fig.SC, the elastic component is located close to the outer surface of the final product. Locating the elastic component in the centre of the strip of nonwoven results in it also being in the centre of the thickness of the tubular product wall Fig.5C. As has been discussed, supra, this method of varying the position of the elastic component between the inner and outer surfaces of the product, allows subtle changes in the nature of the material to be made, to adapt R to varying orthopaedic requirements.

In addition to altering the lateral position of the elastic component, to control the properties of the material, the level of overlap and the weight and thickness of the input nonwoven component can be used to control the wall thickness of the tube produced.

A machine suitable for manufacturing the presently claimed invention is entitled RontexTm and is manufactured by Dilo GmbH.

This machine is illustrated in Fig.3. As can be seen, an endless band of nonwoven (4) and an elastic thread (5) are spirally fed by 9 rotating rollers (7) onto a stationary mandrel (8) where they are needled by devices (9).

With reference to Figs.4A and 413, the effect of the speed of drawing-off is illustrated (for the purposes of this figure, the elastic component has been omitted): the drawing-off speed of the nonwoven (4) in Fig.4A is lower than in the case of Fig.413, giving the nonwoven product of Fig.4A a higher degree of overlap than that of Fig.413.

Figs.6A and 613 illustrate the winding of two different nonwovens side by side (again, the elastic component has been omitted). As can be see in Fig.6A, the left hand nonwoven (4) is, after winding, totally contained within the right-hand nonwoven (4), the former forming the inner surface of the tubular product, the latter forming the outer surface of said product. In Fig.613, the opposite effect has been achieved. This process allows a product to be created in which the inner surface has entirely different properties from the outer surface and permits considerable control over the final product characteristics.

The invention will be further illustrated by means of the following examples:

Example 1

A tubular product was manufactured using a pre-made fleece consisting of 100% polyester fibres of 5Omm staple length and 4.4 Cex with a nominal weight of 85g/m2. The fleece was sift to a width of 80mm. The elastic component used was a cone of elastomeric yam consisting of a single filament of unwrapped Lycra 0 of 1240 Cex. A roll of the above-mentioned fleece was fed to a Dilo Rontex machine as the nonwoven component. The cone of elastomeric yam was positioned such that its feed was underneath the nonwoven component and laterally positioned in the centre of it. Tension was applied to the LatexTm as R was fed in, so that it would be in a partially stretched state in the finished product. The Rontex machine was operated such that the tubular product consisted of six overlapping layers, which were then needled together. The tube had an internal diameter of 6cm and would be suitable for application to some lower arms.

Example 2

This example was the same as example 1, except that three overlapping layers were used instead of one.

Example 3

This example was as example 1, except that the input nonwoven consisted of 100% viscose fibres with a staple length of 38mrn and 3.3 Cex. Nominal weight was 105g/m2.

Example 4

This example was as example 2, except that the input nonwoven consisted of 100% viscose fibres with a staple length of 38mm and 3.3 Cex. Nominal weight was 105g/m2.

As well as solving the above-mentioned problems, the present product has the advantage that R can be provided in endless lengths. These can be cut into rolls of say 5m length, i.e. sufficient to 11 treat say ten lower arm or lower legs. Lengths can be cut precisely to size. In addition, different tube diameters can be provided such to suit a range of limb diameters from paediatric to adult.

Although the tubular product of the present invention has primarily been conceived for use as an undercast padding, it also has other applications, particularly in the medical field.

lz

Claims

1. A tubular fabric in which comprises at least one spirally wound nonwoven component and a spirally wound elastic component wherein consecutive windings of said at least one nonwoven component overlap one another and each winding of said elastic component is sandwiched between adjacent overlapping windings of the at least one nonwoven component.

2. A tubular fabric as claimed in claim 1 in which the windings of the nonwoven component are interconnected.

3. A tubular fabric as claimed in any preceding claim in which the nonwoven material has a weight range of 20-1 00g1M2.

4. A tubular fabric as cJaimed in any preceding claim in which the spirally wound elastic component when wound are spaced from 3 to 12mm from each other.

5. A tubular fabric as claimed in any preceding claim in which the nonwoven fibres comprise fibres which are selected from the group consisting of; viscose, polyester, cotton and mixtures thereof.

6. A tubular fabric as claimed in any preceding claim in which the nonwoven component of the finished product makes up at least 50% of the total weight of the material.

7. The use of a tubular fabric as defined in claim 1 as a bandage.

8. A tubular fabric as substantially herein before described with reference to any one of the embodiments illustrated in the accompanying drawings.

9. A method of manufacture of a tubular fabric having an elastic component and at least one nonwoven component comprising the step of spirally wrapping the elastic component and at least one nonwoven component around a stationary mandrel such that 13 consecutive windings of at least one nonwoven component overlap each other and each winding of said elastic component is sandwiched between adjacent overlapping vAndings of said at least one nonwoven component.