GB2112425A - Flame retardant fabrics - Google Patents

Abstract

A warp knitted fabric is knitted from a first yarn and a second yarn, both yarns having flame retardant characteristics, the first yarn being knitted to produce a plurality of parallel pillars or chains extending in the warp direction of the fabric to form a scaffold and the second yarn being inserted into the fabric at a relatively low or zero tension, said second yarn extending generally in the weft direction of the fabric and interconnecting said pillars or chains at intervals spaced in the warp direction. As shown front and back loops F, B of a double chain are formed of the first yarn on two needle bars while two second yarns X, Y interconnect the chains. <IMAGE>

Description

SPECIFICATION Flame retardant fabrics The invention relates to a flame retardant fabric and more particularly concerns knitted fabrics which are knitted from a textile yarn having flame retardant properties.

Many fabrics which are available at present exhibit poor flame retardancy. In particular, fabrics used, for example, as bed linen, are produced from cotton which not only has poor flame retardancy characteristics but also has poor washability.

Flame retardant textile yarns are available but hitherto fabrics produced from such yarns exhibit both poor handle and also poor dimensional stability particularly during washing.

We have found that it is possible to produce a fabric having acceptable handle from yarns which have flame retardant properties.

It is an object of the present invention to provide a flame retardant fabric which has good handle. It is a further object of the invention to provide such a fabric which also exhibits good dimensional stability and good washability.

According to the present invention, we provide a knitted fabric which is knitted from a first yarn and a second yarn, both yarns having flame retardant characteristics, the first yarn being knitted to produce a plurality of parallel pillars or chains extending in the warp direction of the fabric to form a scaffold and the second yarn being connected into the fabric at a relatively low or zero tension, said second yarn extending generally in the weft direction of the fabric and interconnecting said pillars or chains at intervals spaced in the warp direction.

Preferably, the first yarn is knitted so as to produce double pillars or chains.

Preferably, two second yarns are knitted in to the fabric and to achieve this a machine incorporating two yarn feeder bars may be employed.

The resulting fabric comprises a structure incorporating pillars or chains with interconnecting weft yarns at spaced intervals. Because of the fact that the weft yarns are laid in at a relatively low tension, the resulting product adopts an open configuration with diamond-shaped openings between adjacent pillars or chains, the edges of the diamonds being defined by the pillars or chains and the corners of the diamonds being defined by the position at which adjacent pillars or chains are interconnected by the second yarn or yarns.

The fabrics of the present invention can be knitted from a variety of flame retardant yarns which may be filamentary yarns or yarns which are spun from flame retardant staple fibres. Generally, it is preferred that the second yarn should have greater bulk than the first yarn although if desired, the same yarn or a yarn having less bulk can be used.

The additional bulk of the second yarn can be achieved by using a coarser yarn or by using more ends of a similar yarn.

Particularly preferred yars for use in the invention are flame retardant polyester yarns which may be in filament form, including texturised filaments, or spun from staple fibres.

The flame retardant fabrics produced in accordance with the invention are particularly suitable for use in contract applications where an open fabric is acceptable. An example of such an application is for blankets for hospital use where superior dimensional stability and washability characteristics are very important in addition to the required flame retardancy.

Reference is now made to the accompanying drawings, in which: Figure 1 shows schematically a fabric according to the present invention; Figure 2 illustrates the formation of a pillar or chain forming the warp of a fabric according to the invention; Figure 3 shows the stitch formation of a plurality of pillars or chains as shown in Figure 2 together with the interconnecting weft yarns.

A fabric according to the invention is shown schematically in Figure 1. It comprises a plurality of warp knitted pillars or chains 10, 11, 12 and 13 extending in the warp direction, the pillars or chains being interconnected at intervals spaced in the warp direction. Such interconnections are illustrated schematically in dashed lines, interconnections 14 being between warp pillars or chains 10 and 11, interconnections 15 being between warp pillars or chains 11 and 12, and interconnections 1 6 being between warp pillars or chains 12 and 13. The structure of the fabric defines a plurality of diamondshaped openings 17.

The fabric structure illustrated in Figure 1 is achieved by knitting a plurality of pillars or chains as illustrated in Figure 2. These pillars or chains are knitted using a two needle bar machine, a front needle bar being used to form the front loops identified as 1 F, 2F and 3F in Figure 2 and a back needle bar used to form the back loops 1 B, 2B and 3B in Figure 2. The loops are formed in the order 1 F, 1 B, 2F, 2B, 3F, 3B and so on.

Two further sets of yarns are knitted into the fabric, these yarns being identified as X and Y in Figure 3. The pillars or chains are identified as F or B in Figure 3 depending upon whether they constitute front pillars or chains F or back pillars or chains B. It will be appreciated by a person skilled in the art that Figure 3 shows only the basic loop structure.

It will be seen from Figure 3 that eacy yarn X and Y is connected in to a chain or pillar for three courses without any interconnecting links and the next three courses are provided with interconnecting links X1 and1, this arrangement extending throughout the fabric. The interconnecting links extend from a front pillar or chain F across to the next but one back pillar or chain B and from a back pillar of chain B across to the next but one front pillar of chain F the yarns X and Y alternating throughout the fabric.

The X and Y yarns are laid in by means of a pair of yarn feeder bars which are threaded half set so that they do not feed yarn to the same needles at any particular course.

The yarns X and Y are fed with a very low yarn tension which provides a fabric having desirable characteristics including thermal properties due to the bulk of the fabric and a relatively soft handle to both sides of the fabric. Identical knitting movements are in opposition diagonally to give transverse stability.

EXAMPLE A The fabric described above was knitted using a TREVIRA FR multi-filament yarn incorporating false twist and having a low K factor. The pillars or chains were knitted from a single end of yarn whilst the interconnecting yarns comprised two ends of yarn.

The resulting fabric exhibited good dimensional stability and had a relatively soft handle.

Flammability A sample of the fabric described in Example A was subjected to the flammability test defined in British Standard BS No. 5867 part 2 type C and was satisfactory.

Fabric Stability.

EXAMPLE B A sample of the fabric described in Example A in the form of a blanket was washed using the following process: 300 Ibs. load of cotton white work 5 mins. 12" Dip Cold water Drain 5 min. 8" Dip to 600C -with Pennzyme non ionic detergent plus Perborate.

10 min. Raise temperature to 750C Drain and interspin (medium speed) Two rinses followed by inter spin Last rinse with softener 10 min. High Speed spin.

After 50 such washes the blanket dimensions had changed by a relatively small amount the dimensions before washing being 75.1/2" x 76" and after washing 80.1/2" x 73.1/2".

After 100 washes the handle of the blanket remained good.

EXAMPLE C The following washing test was carried out on a sample of the fabric described in Example A: Test Machine -- Wascator FOM 71 Fabric Load -2.0Kg using H.L.C.C. specified polyester makeweights Liquor levels - 1 0 cm for soaking and washing, 1 3 cm for rinsing Detergent -- Ariel (registered Trade Mark) Specimen size -- 50 x x 50 50 cms The fabric was allowed to soak in the machine for 5 minutes at approximately 200C in plain water.

The water was then removed by draining. The fabric was then washed at 600C for 5 minutes in the Ariel solution, after which time the temperature was raised to 750C and the washing continued for a further 11 minutes. At the end of this wash cycle the liquor was drained away and the fabrics hydro-extracted for 2 minutes. Rinsing was carried out in cold water for 3 minutes followed by a 2 minute hydro-extract.

Two rinses were given.

The specimen and makeweights were tumble dried in a domestic type machine using a heat setting which produced an exhaust temperature of 60-650C when the fabric was dry. After drying the tumbling was continued cold for a further 5 minutes.

Measurements of specimen dimension were made after air conditioning for a minimum of 4 hours.

The above wash and drying operation was carried out 3 times.

Average % Dimensional Change (3 measurements) Length Width Area 1 st wash -1.1/2 -4 -6.1/2 2nd wash -1.1/2 -4.1/2 -6 3rd wash -3.1/2 -3.3/4 -7.1/4 (-) denotes shrinkage (+) denotes extension The percentage dimensional change results, were calculated to the nearest reciprocal fraction, consistent with the unit and total size of the individual measurements made.

EXAMPLE D This test was to prove the durability of the sample described in Example A to repeated washing.

The following wash procedure was carried out.

A 600 Ibs. Cherry Tree Washer Extractor was loaded to 500 Ibs. with the sample and fouled cotton sheets under the following conditions: 5 min. Sluice 1 2" Cold Drain Wash --Pt. 1. 5 min. 8" Dip Heat to 600C Enzyme Detergent + solid perborate.

Pt. 1111 min. 8" Dip Raise Temperature to 750C.

Drain and inter spin Rinse - 3 rinses and inter spins.

Final high speed spin for 10 minutes.

It was found that there was no shrinkage even after 100 continuous washes without drying between washes.

Drying was found to be particularly easy, the whole process including drying to an acceptable temperature taking only about 10 minutes whereas an equivalent cotton product would take over 50 minutes.

Aesthetically the sample showed no change after the washing process.

It can be seen from the above results that the fabrics of the present invention are advantageous in many respects over conventional fabrics. Not only do they have good handle characteristics but they also have satisfactory flame-retardancy and excellent stability.

In addition the fabrics afford a considerable saving in energy costs in washing as compared with the equivalent cotton fabrics. Due to the low absorption factor of the fabrics of the invention energy saving in laundry operations can reach approximately 20% of the present cost of laundering the cotton fabrics.

Claims (4)

1. A knitted fabric which is knitted from a first yarn and a second yarn, both yarns having flame retardent characteristics, the first yarn being knitted to produce a plurality of parallel pillars or chains extending in the warp direction of the fabric to form a scaffold and the second yarns being laid into the fabric at a relatively low or zero tension, said second yarn extending generally in the weft direction of the fabric and interconnecting said pillars or chains at intervals spaced in the warp direction.

2. A fabric according to Claim 1 in which the first yarn is knitted so as to produce double pillars or chains using a knitting machine having two needle bars.

3. A fabric according to any of Claims 1 to 3 in which the second yarn or yarns are knitted into each pillar for at least three courses.

3. A fabric according to Claim 2 in which two second yarns are laid into the fabric.

4. A fabric according to any of Claims 1 to 3 in which the second yarns are knitted into one pillar or chain for two or more courses and the next two or more courses comprise interconnecting yarns to an adjacent pillar or chain.

5. A fabric according to any of Claims 1 to 4 in which the second yarn has a greater bulk than the first yarn.

6. A fabric according to any of Claims 3 to 5 in which the two second yarns are laid in with a similar knitting action but in opposition to one another.

7. A fabric according to Claims 1 to 6 in which at least one of the yarns is a polyester yarn.

8. A fabric according to Claims 1 to 6 in which all the yarns are polyester yarns.

9. A fabric according to Claims 1 to 8 in which the yarns are in filament form.

10. A fabric according to Claims 1 to 9 in which the yarns are spun from staple fibres.

11. A fabric substantially as herein described with reference to and as shown in the accompanying drawings.

New claims or amendments to claims filed on 27 July 1982.

Superseded claims 1 to

4.

New or amended claims:-- original claims 5 to 11 and appendances correspondingly renumbered.

1. A knitted fabric which is knitted from a first yarn and a second yarn, both yarns having flame retardant characteristics, the first yarn being knitted to produce a plurality of parallel alternate front and back pillars extending in the warp direction of the fabric to form a scaffold, the second yarn being laid into the fabric at a relatively low or zero tension, and extending generally in the weft direction of the fabric and interconnecting pillars of said scaffold at intervals spaced in the warp and weft directions of the fabric, said second yarn interconnecting a front pillar to a back pillar across at least two intermediate pillars and a back pillar to a front pillar across at least two intermediate pillars, the portions of the second yarn passing across said intermediate pillars being at an acute angle to the warp direction of the fabric.

2. A fabric according to Claim 1 in which two second yarns are laid into the fabric.