GB2298612A - Wound dressing laminating arrangement - Google Patents

Description

1K)-) DRESSING LaMlILTIOM The present invention relates to wound dressing lamination.

It will be understood that a wide range of wound dressings are constructed of either an amorphous mass of absorbent fibre or non-woven layers of material including absorbent fibres. It is also a requirement to ensure that these absorbent layers do not contaminate or become adhered to the wound site. In order to avoid contamination and adhesion it is common practice to laminate a permeable but non-stick film to the absorbent layer.

The lamination technique to adhere the film to the absorbent layer generally involves heating and compression. A roller is heated and in association with a relatively cool smooth roller compresses juxtaposed film and absorbent layers.

Typically, the heated roller has a stippled surface of regular points in order to provide consistent bonding. It will be understood that the objective is to provide maximum bonding whilst achieving adequate flexibility. More recently, the rollers have been replaced by belts which extend the zone of compression and heating during lamination.

In order to provide consistent bonding in the past as indicated above the stippled surface of the heated roller has been made regular such that there are a known number of raised stipple points within a unit area and so the manufacturer can specify a certain bond strength. Unfortunately, such an approach also causes problems about a cut edge of an eventual wound dressing in that if the edge is located between regular stipple points there is no bonding and the dressing is subject to fraying about this unadhered edge.

An additional problem is that conventional laminating technology results with viscose-type fibres in a marked increase in stiffness due to laminating temperatures used.

Furthermore, by the nature of the laminating process the loft of the layer may be compressed.

It is an object of the present invention to provide a wound dressing laminating arrangement that substantially relieves the above-mentioned problems.

In accordance with the present invention there is provided a wound dressing lamination arrangement comprising a first heated roller and a second roller arranged to compress in use a feed of an absorbent web juxtaposed with a film, the heated roller having an irregularly textured resilient surface layer whilst the smooth roller has a relatively soft compliant surface layer in order to limit compression of the feed of absorbent web and film, the textured layer being substantially random to impart in use an irregular bond pattern between the feed of absorbent web and film during lamination.

Preferably, the textured surface layer of the heated roller has an irregular three-dimensional texture.

Preferably, the heated roller has a temperature in the range 60iC to 1700C dependent upon film type to be used.

Preferably, the textured surface has a leather or sueded type configuration.

An embodiment of the present invention will now be described by way of example only with reference to the accompanying drawing in which: Figure 1 is a schematic illustration of lamination rollers; and, Figure 2 is a schematic plan illustration of a heated roller textured surface.

Traditionally, lamination of a film to a web has been achieved by heating the entire film in order that it adheres to the web. Heating has been achieved using infra-red illumination. Unfortunately for wound dressings bonding through laminating a film across the entire surface of an absorbent web would create too stiff a dressing for practical use. Thus, selective lamination at regularly spaced spots upon the film absorbent layer interface has been used to retain flexibility whilst having good adhesion between film and web. Such regularly spacing of adhesion points creates problems about the edge of a cut dressing through fraying.

In Figure 1, a schematic illustration of a lamination arrangement in accordance with the present invention, a first heated roller 1 is located above a second non-heated roller 2 in a form of mangle. Thus, a juxtaposed assembly of a film 3 and an absorbent web 4 is fed in the direction of arrow A towards the rollers 1,2. Typically, the films and web 4 will be fed at about 300 metres per hour, but this is dependent upon roller temperature etc.

The heated roller 1 has a textured surface 5. This surface 5 as shown in Fig. 2 has an irregular pattern comprising ridges, stipples and other surface features in order to impinge and lightly compress the film 3 into contact with the absorbent web 2. The roller 1 is heated to a temperature in the range 600C to 170-C dependent upon the film 3 type. The film 3 types usually used with wound dressings are polyurethane or polyester coating in order to provide a non-adherent yet porous surface through slits or holes in the film.

The smooth roller 2 has a soft and compliant surface 6 which may be a rubber material. This roller 2 is generally not heated.

In use the arrangement forces the juxtaposed film 3 and web 4 between the rollers 1,2. However, there is only limited mask impression which is compounded through the irregular texture surface of the roller 1 to create a laminated adhesion point between the film 3 and the web 4. It will be appreciated that where the absorbent web 4 is a non-woven needled material any loft created within the material is not substantially crushed by the surface laminated adhesion process. Thus, so-called graded density felts which include non-absorbent fibres but have an expanded structure with voids to accommodate wound exudate may be used more readily in wound dressings-.

It is preferred that the textured surface layer 5 has a three-dimensional random nature. Thus, there will be marginal variation in the localised compression between the film 3 and absorbent web 4 with the possible result of variation in bond strength. Such variation further improves flexibility whilst protecting the expanded structure of the dressing.

An additional advantage with the laminating arrangement in accordance with the present invention is that as illustrated in Fig. 2 little or no consideration must be given to where a wound dressing is actually cut from a roll of laminated material, that is to say the problems of edge fraying are substantially eliminated.

In Figure 2 the area marked 7 if correlated to a sheet of wound dressing material would have lamination at the positions of the random raised ridges and/or stippled surface. As the lamination areas extend across the cut boundary there would be adhesion between the film and absorbent web throughout the periphery of a cut dressing as fraying about the edge would be inhibited.

Typically the roller 1 is heated by tubes near the surface of the roller 1 through which hot water or oil is passed. However, other forms of heating are possible.

It is the irregular stippled nature of the roller 1 which provides adequate bonding whilst retaining flexibility in the wound dressing material created.

It will be appreciated that as an alternative to rollers suitable laminating belt arrangements could be used. Thus, one belt would be textured whilst the other was compliant.

Claims (6)

Claims:

1. A wound dressing lamination arrangement comprising a first heated roller and a second roller arranged to compress in use a feed of an absorbent web juxtaposed with a film, the heated roller having an irregularly textured resilient surface layer whilst the smooth roller has a relatively soft compliant surface layer in order to limit compression of the feed of absorbent web and film, the textured layer being substantially random to impart in use an irregular bond pattern between the feed of absorbent web and film during lamination.

2. An arrangement as claimed in Claim 1 wherein the textured surface layer has three-dimensional irregularity.

3. An arrangement as claimed in Claim 1 or 2 wherein the second roller has a smooth rubber surface to ensure that said surface is soft and compliant.

4. An arrangement as claimed in Claim 1, 2 or 3 wherein the textured surface of the first roller comprises a plurality of ridges and stipples randomly arranged.

5. An arrangement as claimed in any preceding Claim wherein the heated roller is maintained in use at a temperature in the range 60-C to 1700C.

6. A wound dressing laminating arrangement substantially as hereinbefore described with reference to the accompanying drawings.