This invention relates to barrier fabrics.

Such fabrics have wide uses, for example in the manufacture of garments for wear by surgeons and other hospital operating theatre staff. The fabrics are water repellant and prevent contact between the wearer's skin and body fluids which may be infected such as blood, urine and pus. Such repellent fabrics are provided by hydro-entangling webs of textile and woodpulp fibres together and treating the resultant non-woven fabric with fluorocarbons, and waxes. This is well known in the art of creating repellant fabrics.

Garments made from barrier fabrics are manufactured using conventional sewing methods. The puncturing of the fabric by the sewing needle provides a route through which micro¬ organisms, in suspension, might travel. Also, short fibres are broken from the body of the fabric, by the action of the needle. Such lint is a potential carrier of organisms about the operating theatre. The lint may even enter the operative site and cause a reaction after the wound has been closed.

A further use for such fabrics is in applications where contaminated air has to be contained, or people have to be

protected from contaminated air. Such applications can be in the decontamination of buildings which contain dangerous dust or particles, such as asbestos and the like. In these applications, sewn seams have the grave disadvantage that the perforation of the two layers of fabric leaves gaps which can allow contaminated air and contaminating particles to pass therethrough. Further, in the creation of seams by sewing particles of the fabric create a fine lint which can itself constitute a contaminant in certain circumstances.

The present invention seeks to provide a barrier fabric and a method of fabricating a structure, such as a garment from such a barrier fabric, in which these disadvantages are obviated or minimised.

Accordingly, the present invention provides a barrier fabric provided with a heat sealable material.

The heat sealable material can be incorporated within the fabric or can be incorporated on one or both surfaces thereof.

The barrier fabric can be a woven, knitted or a non-woven textile material, made from natural, or man-made fibres, or a combination of natural and man-made fibres, which has been treated with water repellent, or protective coating, by any conventional technique.

The present invention further provides a. method of making a structure from a barrier fabric provided with a heat-sealable material comprising the steps of providing at least two components from the said barrier fabric, placing the components next to one another and applying heat and pressure to join the components together.

The steps of cutting out and placing the components next to one another and applying heat and pressure can be carried out separately, or can be carried out simultaneously.

The heat sealable material can be applied to the barrier fabric by any conventional technique, such as paste coating, dry dot (powder point) printing, scatter coating, or grids of thermoplastics, such as polyolefins, polyamides, polyesters, and poly(ethylene vinyl acetate).

The base material of the barrier fabric in this invention may be formed from natural or synthetic fibres, or a blend of the two. They may be a hydro-entangled fabric containing (or not containing) woodpulp fibre, or may comprise of other nonwoven construction eg spunbond. The factor common to the barrier fabrics described in this invention is that all must possess at least one surface capable of being heat fused to form a

seam. The heat sealability of the fabric being provided by means of some coating, or incorporated into the base fabric structure for example by using thermal bonding fibres.

The advantages of the barrier fabric, according to the present invention, and a garment made from such a fabric are that the handling and flexibility of the fabric are not adversely affected, and that the barrier quality of the garment is improved.

The heat-sealable coating can include other additives to impart special properties such as colour, liquid repellency and the like. Desirably these additives are not such as to adversely affect the fabric properties.

The invention will be described further, by way of example, with reference to the accompany drawings and with reference two examples.

In the drawings;

Fig. 1 is a schematic side view illustrating a first step in the manufacture of a preferred fabric of the invention;

Fig. 2 is an enlarged fragmentary view illustrating a part of the product of the step of Fig. 1;

Fig. 3 is a schematic side elevation illustrating a second step in the manufacture of the preferred fabric of the invention;

Fig. 4 is a plan view showing one platen of a press suitable for use in carrying out a preferred method of manufacturing a garment in accordance with the invention;

Fig. 5 is a schematic fragmentary cross-sectional view illustrating a press suitable for carrying out garment manufacture in accordance with the invention;

Fig. 6 is an enlarged cross-sectional view illustrating a seam in a garment of the invention;

Fig. 7 is a fragmentary schematic view illustrating, in plan, a seam in a garment of the invention; and

Fig. 8 is a view similar to Fig. 7 but illustrating a prior art seam for comparison purposes.

Referring now to Fig. 1, it will be seen that apparatus 10 for carrying out a first step in the manufacture of a fabric of the invention comprises, basically, a feed roll 11 whence a web of silicone paper 12 can be drawn. The web 12 passes

through a nip between rollers 13 and 14. Roller 13 is a printing roller which is supplied with a printing 'ink' in the form of a thermo-plastic fabric bonding agent such as one based on poly(ethylene vinyl acetate). The printing roller 13 is effective to deposit a web of the material on the silicone web 12 in the form of a lattice 15, best seen in Fig. 2 on an enlarged scale. After the rollers 13, 14 the web 12 carrying the printed lattice 15 is cooled and wound on to a roll 16.

In a variation of the invention the grid could be coated directly onto the base fabric.

Referring now to Fig. 2, there is shown, again schematically, apparatus 17 for carrying out a second step in the creation of a fabric in accordance with the invention. In the apparatus 17 a web 18 of barrier fabric whose nature will be apparent from the later examples is fed from a storage roll 19 to the nip between a pair of pressure rollers 20, 21. Also fed to the nip between rollers 20, 21 is the web 12 carrying the printed lattice 15. At the nip between rollers 20, 21 the web 18 and the lattice 15 are brought into contact and subjected to pressure and heat. The heat can be supplied by the rollers 20 and 21 or independently as indicated by the arrows 22.

After the nip between the rollers 20, 21 the web of silicone paper 12 is removed and can be either discarded or re-used in the apparatus 10. The lattice 15 is now securely adhered to one surface of the web 18. Cooling occurs over the region indicated at 23 and the web 18 thence passes to a take-up roll 25 for eventual use in the further methods of the invention, for example in the manufacture of a garment, a shroud for an item of equipment to be dismantled or a container for a contaminated article, in particular contaminated articles such as contain asbestos or other noxious or unpleasant airborne particles. Such items are manufactured by uniting one or more sheets of the fabric made by the aforesaid methods. For ease of description the manufsicture of a garment for the upper part of the human body is described, but it will be appreciated that comparable methods can be used for other garments and for gloves, containers, boxes, shrouds and like articles for other protective applications.

Referring now to Figs. 4 and 5, it will be seen that the described garment 26 is manufactured by sandwiching together and uniting two sheets of barrier fabric of the invention 27 and 28. These two sheets can be separate, or two parts of a folded sheet. In such a folded construction a fold can provide a seam if this is appropriate in the manufacturing process. Two sheets 27, 28 are placed together between two platens 29, 30 of a press. The remainder of the press is

conventional in construction and is not described in any detail. When the sheets of material 27, 28 have intrinsically included therrno-plastic uniting members such as thermo-plastic fibres the sides of the sheets which face each other is not critical. However, if the sheets are only coated on one surface with heat sealing material it is desirable if those surfaces (indicated in the drawing as 27A and 28A) are placed in facing relationship.

The platen 29 has a base 31 which supports an insulating layer 32. Mounted in the free face of the layer 32 is a sealing element in the form of a metal tubular electrically heated element 31 forming the shape of at least part of the garment 26. The element 33 can be supplied with electrical power via leads 34 and will, of course, be thermostatically controlled in order that it heats the fabric only to a desired temperature sufficient to create a bond. In a similar manner the time of pressing will be also controlled.

The platen 30 has a base 35, an insulating layer Z6 and a reaction pad 37 facing the element 5Z .

In Fig. 4 there is shown, in dotted lines, the outline of a pair of pieces of the fabric 38 which have been previously cut to shape and then put in position on the platen Z0. Normally, of course, the pieces of fabric 27, 28 would be positioned on

the lower platen 30 and then the heated platen would be brought down on them.

Fig. 5 illustrates a slight variation in that instead of pre- cut sheets 27, 28 being used, means a.re provided on the two platens for effecting cutting simultaneously with the heating.

Such means is shown in Fig. 5 by the items 39. Such means 39 can be either a sharp knife which would cut into the reaction part of 37, or could be a second heating element heated to a much higher temperature which would (a) form a secondary seal at the seam and (b) cut away the outer portions of the sheets 27, 28 by melting them completely.

An example of a base fabric for use in making a fabric of the present invention is a barrier fabric manufactured by the applicants and sold under their identification T30101/4B.

This fabric is an approximately 80g/m ² polyester cellulosic barrier fabric comprising a base non-woven face fabric (25% polyester, 25% viscose, 50% wood pulp) having a fluorochemical repellent finish and usable as an operating room material. An adhesive net was applied to this fabric and the net was a commercially available net sold by Protechnic, 66 Rue de Fabric BP43F68700 Cernay, France. This net is under the trade

mark TEXIRO . The net was a diamond lattice structure on a silicone carrier paper. The net was of poly(ethylene vinyl acetate) and was of a diamond lattice pattern type GNO at 35 g/m ² .

When converting the fabric of the example into a garment the method described in relation to Figs. 4 and 5 was carried out. The temperature of the heating element was selected to be 160°C, the pressure was 300 g/m ² and the dwell time was 9 seconds.

Articles, structures and clothing produced in this way were excellent barrier fabrics preventing passage of dust and particulate materials directly through the fabric and through their seams. The fabric also maintained excellent © and during the manufacture of the article or of the clothing no lint or other loose materials were generated to adhere to the final article or garment.

Clothing produced was excellent for use as an operating gown or as part of an operating suit. The fabric was water repellent and non-permeable.

The adhesive net used can vary widely in its character and various types was selected for different applications. For example, as well as poly(ethylene vinyl acetate) polyamide and

polyester can be used. There is a range of weights 13 - 40 g/m ² and various webs and patterns can be used. EVA net having bonding temperatures in the manufacture of articles from the fabric from 80 - 90°C, or the higher ranges preferred for operating room applications.

As an alternative to the coating with net of fusible polymer, the base fabric weighing approximately 80 g/m ² and containing 25% polyester, 25% viscose and 50% woodpulp was foam coating with approximately 17 - 19 g/m ² of a heat sealable polymeric binder in the form of a foam coating. After manufacture this fabric could be seamed by applying heat at a temperature of 120°C at low pressure for a few seconds.

As a further alternative a polyamide net can be used at 13 g/m ² as the adhesive mesh. This material can be applied and sealed at 110 - 125°C.

As a further variation a base fabric of 45 g/m ² non-woven base 100% polyester was foam coated with approximately 12 - 14 g/m ² of heat sealable acrylic binder. After manufacture this fabric could be heat seamed by applying heat at a temperature of 120 ^* C for a few seconds at low pressure.

The pressure can be less than 300 g/m ² for example, from 150 - 350 g/m ² and the dwell time can be in the range of 0.5 -20 seconds.

The preferred sterilisation method for OR gowns is gamma radiation. However, were steam sterilisation required, for example at 134°O, the fusing component would be required not to soften below 140°C. However if a low temperature bonding is satisfactory, it is possible to use a fusing temperature below 140°C provided that sterilisation techniques are taken into account and high temperature autoclaving is eliminated as a possible means of sterilisation.

In each of the examples the two sheets of fabric 27, 28 were united by a seam 40 which was formed of a continuous length 41 of fusible material, this is best seen in Figs. 6 and 7. Although, in practice, the length 41 may not be completely continuous, the gaps between the portions thereof are very small and in those gaps the sheets 27, 28 are closed drawn together such that airborne particulates have a great deal of difficulty in passing through the seam. In the case of a lattice of fusible material to ensure a continuous seam it is advantageous to make seam width greater than the lattice unit dimension.

In contradistinction, Fig. 8 shows prior art wherein a pair of sheets 42, 43 are united by a sewing thread 34 passing through holes 45 made by a sewing machine needle.

Because the stitches are of necessity spaced apart, there is always the possibility that the join between the fabric can (especially if the tension is incorrect) gape as indicated at 46. However, a major and ever present source of through aii— flow is via the holes 45 created by the sewing machine needles. However well sewn, it is a fact that the holes made by a sewing machine needle are invariably larger than the thread 44 and this leaves a gap through which contaminated air- can be driven as indicated by the arrows 47.

The garments manufactured in accordance with the present invention do not have this disadvantage and this makes a superior performance.

The invention is not limited to the precise details of the foregoing description and example and variations can be made thereto.

For example, the invention can be applied to barrier fabrics and methods of fabricating using barrier fabrics for all purposes other than de-contamination and operating and closing. The barrier fabric and the articles made therefrom

can be used in any situation where air filtration effect is needed to keep particulate contaminated air from entry to some other area. The invention provides a relatively cheap and simple way of providing a seamed structure which has all the advantages of cheap particle impervious barrier fabric together with cheap easily produced and particulate proof seams.

Of course, the barrier fabric itself can be any convenient fabric and is not limited to the two examples described. The barrier fabric can be woven, knitted or of non-woven construction or of any other convenient form. It can be water repellent or water absorbent depending upon the application.

The heat sealable material can be applied externally to the barrier fabric by any conventional techniques such as paste coating, dried or powder point, printing, scatter coating or by the methods described herein. The @ use can be thermo- plastic polyolefins, polyamides and/or polyesters. It is, of course, desirable that heat sealable material is chosen so as to satisfy some or all ^" of the following criteria:-

a) to seal below 180°C, or some other higher level depending on the nature of the fabric. In certain applications there can be a minimum fusing temperature

of 140 ^Λ C, particularly if steam autoclaving at 134°C is contemplated.

b) the material should be sufficient to provide a bond of sufficient strength for the end use and preferably equal to or greater than a bond capable of creation by sewing

c) the material should have a minimal effect on the handle of the fabric

d) the material should be non-tacky at room temperature so as to facilitate handling and storage. However, in applications where there is a special facility for storing, or where tackiness is desired for use during the final construction, tacky adhesive can be used and protected by a release coating if necessary.

e) desirably the sealable material is stable to gamma radiation if such radiation be required for sterilisation or other applications

f) the heat sealing material should be non-toxic

g) the heat sealing material should be aesthetically pleasing, non-abrasive and should not shed particles

h) the material should be as light as possible yet achieve a strong bond. Weights of the material can reach 50 g/m ² .

Instead of being applied simply to one or both surfaces of a sheet of barrier fabric the heat sealable material can be incorporated in the fabric either as a particulate material, or as a fibre during its construction.

In a continuous production method garments can be produced by a continuous roller press rather than the intermittent platen press illustrated in Figs. 4 and 5. In such a case the necessary elements and cutters will be arranged on the surface of a roll or rolls and a web or webs of fabric fed continuously therethrough. Heating other than electrical can be used to heat seal the fabric for example radiant or convective heat or ultrasonic high frequency heating can be used. A portable sealing tool can be provided so that after, for example, a contaminated item has been placed in a bag made from the barrier material in accordance with the invention a seal can be created in that bag to form a sealed enclosure in which the contaminated article can be stored for further treatment and/or disposal.

Many other variations are possible within the scope of the claims.