Fabric (woven – knitted – or nonwoven textile or cloth – etc.) – Scrim – Woven scrim
Reexamination Certificate
2002-03-26
2004-03-02
Ruddock, Ula C. (Department: 1771)
Fabric (woven, knitted, or nonwoven textile or cloth, etc.)
Scrim
Woven scrim
C442S020000, C442S021000, C442S025000, C442S049000, C442S301000, C428S920000, C428S921000
Reexamination Certificate
active
06699802
ABSTRACT:
This invention relates to fire resistant textile materials and garments made from these materials. The invention relates particularly but not exclusively to articles of clothing for use by fire fighters and for textiles for manufacture of such clothing.
European legislation requires employers to provide garments which protect their employees against hazards to which they may be exposed. Clothing for protection against heat and flame must pass minimum performance requirements for flame, radiant heat, heat resistance, tensile and tear strength, abrasion resistance and penetration by water and liquid chemicals. The assembled garments must achieve levels of resistance to heat transfer by both flame and radiant heat.
One of the most effective ways to reduce second and third degree burns is to make sure that the barrier of protective clothing between the heat source and the skin remains intact during exposure. This is referred to as the break open resistance or non-break open protection.
An object of the present invention is to optimise thermal protection offered by the fabric. We have discovered that this can be achieved through use of enhanced fabrics design and fiber utilisation.
Outer textile materials for fire fighting clothing have previously been manufactured from 100% meta-aramid or polyamide imide, blends of meta-aramid and para-aramid fibres or by use of core spun yarns or staple mixtures with polyparaphenylene terephthalamide copolymer or fibres comprising para-aramid cores with meta-aramid or polyamide imide covers. The combination of these fibres in the fabric enhances the non-break open protection of the product. However, meta-aramid and polyamide imide fibres shrink, consolidate and thicken when exposed to a high temperature heat source. The presence of para-aramid or polyphenylene terephthalamide copolymer in either the fibre blend or as a core can be used to prevent fibre shrinkage and consequent breaking open of the garment. However the inclusion of para-aramid fibre in the blend has been found to be insufficient in tightly woven fabrics to prevent breaking open. Consequently there is a need for improved textile materials for manufacture of fire fighting garments and the like.
Fire fighting garments have been made from a plurality of textile layer, including an outer layer of woven meta-aramid fibre, for example as manufactured under the trade mark Nomex. Break open protection may be afforded by blending with para-aramid fibres, eg as manufactured under the trade mark Kevlar and as disclosed in U.S. Pat. No. 3,063,966 and U.S. Pat. No. 3,506,990. However changing of such blends may lead to cracking and embrittlement with consequent deterioration of physical properties.
DE-A-29611356 disclose a protective glove, resistant to cutting wherein a two layer weave has an outer side of meta-aramid fibres and an a side of para-aramid fibres.
According to the present invention a fire resistant textile material comprises a woven face fabric composed of fibres selected from meta-aramid, polyamide imide and mixtures thereof, the fabric including a woven mesh of low thermal shrinkage fibres.
Use of low thermal shrinkage fibres in accordance with the present invention increase the residual tensile strength of the textile material following exposure to flame or a radiant beat source. Low thermal shrinkage fibres in accordance with this invention may be defined as a fibre which exhibits not more than 6% shrinkage when exposed to a temperature of 400° C. for a period of 5 seconds.
Low thermal shrinkage fibres in accordance with the present invention may be selected from the following materials:
polyparaphenylene terephthalamide (par-aramid eg Kevlar), polyparaphenylene terephthalamide copolymer, polyamide imide, copolyimide, phenolic fibres obtained by cross-linkage of phenolaldehyde resin and containing more than 70% carbon, polybenzimidazole , polyetheretherketone, high tenacity silicon carbide both with a core and with an organic precursor, ceramic fibres including alumina, alumina silicate and borosilico aluminate; and glass fibres including E glass, C glass, D glass and R glass. Mixtures of the aforementioned fibres may be employed.
Preferred low shrinkage fibres are selected from para-aramid, polyparaphenylene terphthalamide copolymers; polyamide imide; carbon fibres and mixtures thereof.
Fibres or yarns composed of 100% polyparaphenylene isophthalamide meta-aramid (eg Nomex) shrink upon exposure to high temperatures, for example in exces of 295 EC. This shrinkage can result in a whole garment exposed to a flame. The low thermal shrinkage fibres, for example para-aramid fibres or yarns do not shrink to the same extent on exposure to this temperature (The thermal shrinkage of Kevlar is about 3%, whilst the thermal shrinkage of Nomex is about 24%). If the two fibres or yarns are combined in a fabric, the shrinkage of the fabric may be controlled and/or restricted in such a way that the formation of holes, or break opening, is minimised. The direction of the distortion of the fabric when in the cross-sectional direction when exposed to a high temperature may be controlled so that the fabric becomes thicker. This control is achieved by use of a woven or warp knitted face fabric. This serves to increase the thermal protection afforded by the fabric and increases the number of seconds needed to raise the temperature on the inner side to a level which would create pain or a second degree burn on human skin or on the type of sensor used in Thermal Protection Procedure (TPP) testing.
Fire resistant fabrics in accordance with this invention confer a further advantage in comparison to fabrics composed of an intimate blend of meta-aramid and para-aramid fibres. Fabric formed from an intimate blend exhibits poor retention of the new appearance. The presence of low thermal shrinkage fibres on the surface of a garment for example Kevlar results in formation of fine fibrils due to abrasion in use. Colored fabrics, for example dark blue as used for fire fighters? tunics may develop light specks on the surface of the fabric. This gives an uneven appearance on a dark colored garment Fabric frosting is the term used to describe this effect.
The low shrinkage fibres are preferably disposed behind the face fabric. This minimises exposure of the strengthening fibres to the heat source.
Fabrics in accordance with the present invention also have the advantage that degradation of the low thermal shrinkage fibres, which are more susceptible to ultra-violet light degradation than other fibres, is reduced because they are not located on the outer surface of the fabric.
In preferred embodiments of the invention the low thermal shrinkage fibres form an interwoven backing scrim on the back of the face fabric. The low thermal shrinkage fibres preferably comprise para-aramid or polyparaphenylene terephthalamide copolymer, eg Kevlar yarns. The thickness of the yarn may be selected in accordance with the resultant mass and weave of the finished fabric. The resultant mass (g/m
2
) will vary dependent on the particular end use but will generally be within the range 150 to 300 g/m
2
. The woven fabric is preferably a combination of a face fabric into which is interwoven a backing scrim. The weave of the face fabric may vary dependent upon the mass and end use required. The interweaving of the backing scrim will be dependent on the weave of the face fabric and the thermal performance required.
Fabrics in accordance with this invention may be produced by interweaving yarns which have been spun and plied or core spun from staple fibres and/or multifilament fibres which may comprise 100% meta-aramid, 100% para-aramid, 100% polyamide imide or intimate blends of any combination of these fibres.
The interweaving of the selected yarns may be such that a closely woven fabric suitable for use as the outer face of a garment is combined with a loosely woven fabric which is suitable for use as the reverse side of the garment.
The selection of fibres and yarns which may be incorporated into fabrics in accordance with this
Hainsworth Thomas
Walker Derek
A W Hainsworth & Sons Ltd.
Ruddock Ula C.
LandOfFree
Fire resistant textile material does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Fire resistant textile material, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Fire resistant textile material will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3203626