US3476629A - Process for metallizing fabrics - Google Patents

Description

Nov. 4, 1969 G. J. PARISH PROCESS FOR METALLIZING FABRICS Filed Feb. 8. 1966 R m w m GEOFFREY J. PARISH United States Patent US. Cl. 156-251 13 Claims ABSTRACT OF THE DISCLOSURE A process for making porous metallised fabric consists of a porous basic fabric having adhered to a surface thereof a thin metal sheet ruptured at some of the interstices of the basic fabric and also broken up into small substantially discreet fragments. Breaking up of metal sheet is accomplished by embossing the fabric-metal laminate.

This invention concerns metallised fabrics.

In U.S. Patent No. 3,034,940assigned to the assignee of the present application, there is described and claimed a porous metallised fabric of the kind (hereinafter termed of the kind referred to) consisting of a porous basic fabric having adhering to at least one surface thereof a thin sheet of metal which conforms to the surface contours of the basic fabric and is ruptured at a sufficient number of the interstices of the basic fabric to give the required degree of porosity, the ruptured parts of the metal sheet extending inwardly of the respective interstices to conform to the wall contours of the latter.

In Patent No. 3,034,940 there is described and claimed a method for producing a porous metallised fabric of the kind referred to wherein the metal sheet is laid on the surface of the fabric and pressed into place by the direct application thereto of a resiliently deformable material, and wherein the pressure applied is sufficient to cause the sheet to conform to the Surface contours of the fabric and to rupture at a sufficient number of the interstices of the fabric to give the required degree of porosity, and the ruptured parts of the sheet to extend inwardly of the respective interstices to conform to the wall contours of the latter.

Whilst metallised fabrics of the kind referred to and prepared in the manner described in the above-identified patent aforesaid have been claimed to have better handle and draping properties than metallised fabrics in which the foil is not perforated they are inevitably stiffer than the base fabrics with which they are formed.

The present invention is based on an appreciation that increased flexibility will result if the foil can be further broken up. By this is meant not simply an increase in the depth or extent of perforation but a cutting or tearing of the foil into small, more-or-less discrete fragments.

Thus, according to the present invention a porous metallised fabric of the kind referred to is characterised in that the metal sheet in addition to being ruptured at a number of the interstices of the basic fabric is broken up into small substantially discrete fragments.

The invention will be further apparent from the following description with reference to the single figure of the accompanying drawing, which shows, in diagram- 3,475,629 Patented Nov. 4, 1969 "ice matic form, by way of example only, one type of apparatus for producing metallised fabric embodying the invention.

Referring now to the drawing it will be seen that use is made of a calender or mangle comprising a hard bowl or roller 15 working against a bowl or roller 16 provided with a covering 17 of soft vulcanised rubber, eg 34 BS. degrees hardness. A continuous sheet of thin aluminium foil 7, is coated on one face with a thin layer of adhesive :1 by being drawn through the roller coater mechanism 18 with doctor knife attachment 19 and is then feed into the calender or mangle together with the fabric F to be coated which is also in continuous length. The uncoated face of the aluminium foil 1 is in contact with the rubber coated bowl or roller of the calender or mangle, the coated face of the foil being in contact with one face of the fabric 10, the other face of the fabric being in contact with the hard bowl or roller of the callender or mangle.

The presure in the nip of the calender or mangle is so arranged that the aluminium foil is forced into pressurised contact with the basic fabric F to such an extent that the foil 1 assumes the surface contours of the basic fabric F and becomes ruptured at a substantial number of the interstices thereof, the ruptured parts of the metal sheet extending inwardly of the respective interstices to conform to the wall contours of the latter.

The composite sheet product leaving the calender or mangle is, of course, a metallised fabric of the kind referred to, and as described in Patent No. 3,034,940.

The next stage is to break up the aluminum foil into a multiplicity of small, more-or-less discrete fragments, and it is desirable that during any process for achieving this, the adhesive bond between the foil and base fabric should not be unduly disturbed. A suitable procedure is to emboss the laminate, using a small all-over pattern, and then to press the material flat again. The embossing action produces local deformations which break the foil and a mechanical action alone is effective; the additional use of heat is probably undesirable since it could lead to a permanent emboss with some fabrics, which itself could increase the laminate stiffness. Pressing flat is designed to prevent this effect, but it is probably impossible completely to remove the embossed pattern.

Thus, the composite sheet is passed through the nip of a calender or mangle comprising a bowl or roller 20 having a rubber covering 21, and a bowl or roller 22 covered with a wire gauze 23, for the purpose of embossing the foil Finally, the composite sheet is pressed flat by passage through the nip of a further calender or mangle comprised by a bowl or roller 24 having a rubber covering 25 and a bowl or roller 26 of smooth stainless steel.

In one experiment the composite sheet was embossed under the following conditions: load at nip 400 pounds per linear inch; speed 15 yds./min.; bottom roller 9 inch diameter, covered with 20 mesh, 28 s.w.g. brass gauze; top roller 6-inch diameter, covered with rubber of about 40 B.S. hardness, inch thick. Samples were embossed with either the foil or the fabric surface in contact with the gauze-covered roller, and some samples were given repeated passages through the nip. After embossing the samples were pressed flat by one passage through a similar nip but with a bottom roller of smooth stainless steel; in this case the foil surface was always in contact with the rubber-covered roller. These tests were made with a composite sheet consisting of a base fabric of cotton, plain 3 weave, 64 x 60, 36s yarns, weighing 2.7 ounces per sq. yd. and aluminium foil 0.00025 inch thick. Measurements of bending length have been made, and the results are shown in the following table.

In commercial exploitation of this invention it is envisaged that embossing could be carried out by the method used experimentally; but with an engraved roller in place of the gauze-covered roller, or by the use of a conventional embossing machine with mating rollers. The pattern of the embossing is not critical, but it is important that the emboss should be deep enough to rupture the foil, but the pattern should not be so large that the foil breaks are widely separated. Satisfactory results have been obtained with a gauze of mesh, and it would seem likely that a size between this and about 30 mesh would be usable.

The flattening operation need not necessarily be in a nip employing a soft thin rubber cover; a conventional mangle or calender could be used, providing the load were not so high that this operation itself stiffened the material.

It will be appreciated that it is not intended to limit the invention to the above example, many variations, such as might readily occur to one skilled in the art being possible without departing from the scope thereof.

The embossing process need not be carried out as a separate operation after laminating, but may be carried out simultaneously with foil perforation and lamination by using an engraved roller in contact with the fabric in place of the plain roller previously described.

Furthermore, the process need not be carried out continuously, but may be performed for the production of relatively small sheets, using suitable platen presses or the like.

I claim:

1. A method of producing a porous metallised fabric comprising the steps of applying a thin sheet of metal to a basic fabric composed of strands defining an inherent multiplicity of interstices between them, pressing the metal sheet into adherent relation with the fabric with a pressure sufiicient to cause the sheet to conform to the surface contours of the fabric and to rupture in some regions overlying the interstices and cause the ruptured parts of the metal to extend into their respective interstices in form-fitting relation to the walls thereof, and embossing the fabric and metal with a pressure which presses the fabric and metal together and is of sufiicient magnitude to break the metal into discrete fragments, by passing the fabric and metal between two surfaces, at least one of which presents a profiled surface having a small over-all pattern.

2. A method according to claim 1 wherein said pressing step takes place prior to said embossing step.

3. A method according to claim 1 wherein said pressing step takes place simultaneously with said embossing step.

4. A method according to claim 1 wherein after said embossing step the fabric and metal are pressed together to flatten the metal sheet fragments.

5. A method according to claim 1 wherein the metal sheet is pressed fiat after embossing by passing the metallised fabric through the nip of a mangle constituted by rollers having smooth surfaces.

6. A method according to claim 1 wherein said embossing step comprises passing a metal sheet and basic fabric in superimposed relationship through a nip comprised by two rollers, one of which has a covering of resiliently deformable material, and the other of which presents a profiled surface having a small all-over pattern, the metal sheet being in contact with the roller having a resiliently deformable covering.

7. A method according to claim 1 wherein the embossing step is carried out by passing the fabric and metal through a nip formed by two rollers, at least one of which presents a profiled surface having a small over-all pattern.

8 A method according to claim 7 wherein one of said rollers has a covering of resiliently deformable material.

9. A method according to claim 7 wherein said profiled surface is constituted by engraving on the surface of the roller.

10. A method according to claim 7 wherein said profiled surface is constituted by a covering of wire mesh over the surface of the roller.

11. A method according to claim 10 wherein said mesh has a mesh size lying in the range of from 10-30 mesh.

12. A method according to claim 7 wherein said fabric and metal are passed through said nip with the metal in contact with the profiled surface.

13. A method according to claim 7 wherein said fabric and metal are passed through said nip with the fabric in contact with the profiled surface.

References Cited UNITED STATES PATENTS 3,034,940 5/1962 Collins et al 161-111 X 3,099,596 7/1963 Prew l56380 2,970,345 2/1961 Wangner.

ROBERT F. BURNETT, Primary Examiner M. A. LITMAN, Assistant Examiner US. Cl. X.R.

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