Stock material or miscellaneous articles – Structurally defined web or sheet – Including aperture
Patent
1992-08-27
1997-08-12
Page, Thurman K.
Stock material or miscellaneous articles
Structurally defined web or sheet
Including aperture
428137, 428138, B32B 310
Patent
active
056563523
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a novel fabric.
BACKGROUND ART
Insulating fabrics are known which comprise an impermeable, thermally efficient sheet material such as neoprene rubber. Such fabrics are, however, not wearable next to the user's skin for extended periods of time, mainly due to the interference they can cause to the natural biological functions of the skin, in particular perfusion of the skin with oxygen and removal of natural excretions such as water vapour, salt, urea and carbon dioxide.
Previous efforts to improve the wearability of impermeable materials have included perforation of the material and lamination with a more skin-compatible material such as woven cotton.
British Patent No. 1267712, for example, describes. (FIG. 4) a breathable fabric in which a perforated elastomeric sheet is bonded between stretch-fabric sheets. The diameter of the perforations reduces slightly towards the outside of the finished garment to facilitate manufacture.
Such fabrics are reasonably wearable given normal external conditions and the biological functions of the wearer. However, if for example the wearer sweats or warms up during exercise or under stress, or the external temperature or humidity rises or falls, or the fabric becomes soaked with water, or in other abnormal situations, the breathable efficiency of the fabric declines rapidly, which can make the garment extremely uncomfortable or even dangerous to wear. Such poor adaptability has limited the use of breathable elastomeric fabrics, for example for insulating and/or protective garments, for medical or veterinary garments and/or dressings (where the patient's skin may be injured or prolonged close contact with the skin may be required), or for exercise and sports garments where rapid changes of perspiration and other skin functions take place. The present invention aims to provide a breathable fabric which goes at least some way towards overcoming the above disadvantages.
According to the present invention, there is provided a fabric comprising a sheet formed of a substantially impermeable material having perforations provided therethrough, each perforation having at least one relatively wide region and at least one relatively narrow region along its length to define an internal chamber open to a first ("inner") side of the sheet and sufficiently closed to the other ("outer") side of the sheet to permit air passing from the first to the other side of the sheet to accumulate in the chamber under increased pressure prior to passing out to the other side of the sheet.
The expressions "relatively wide" and "relatively narrow" mean that the respective regions are wide and narrow relative to each other. The expression "fabric" includes a fabric portion, and the expression "sheet" includes a sheet portion.
The substantially impermeable sheet may be a unitary sheet or a laminate, and is preferably elastomeric (e.g. formed from a rubber such as neoprene rubber). In the case of a laminate, different materials may if desired be used for different lamina so as to provide overall a sheet having the desired properties.
Closure of the chamber to the outer side of the sheet by a relatively narrow region of the perforation, in the resting condition of the sheet, may be complete or partial, and the materials and/or chamber configuration are suitably chosen so that on stretching and/or bending of the sheet or one or more particular lamina thereof the relatively narrow region opens wider than its resting condition to allow exchange of air between the two sides of the sheet. Stretching/bending so as to cause the relatively narrow region of the perforation to open typically results from the desired build-up of pressure in the chamber and/or by movement of the fabric in use.
The arrangement may also suitably be capable of creating a pumping effect in the chamber(s) by the periodic stretching and/or bending of the fabric in use, to assist the exchange of air between the inner and the outer sides of the sheet.
In general, it is preferred that even a
REFERENCES:
patent: 4636424 (1987-01-01), Amemiya et al.
patent: 4846164 (1989-07-01), Martz
Micro Thermal Systems Limited
Page Thurman K.
Shelborne Kathryne E.
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