Flame Retardant Fabric Comprising Cotton Alternative

Abstract

The present disclosure relates to a flame retardant (FR) treated fabric, comprising yarns formed from a mixture of natural and/or synthetic fibres, the fabric further comprising FR treated lyocell fibres, wherein the FR treatment is a non-cellulose-reactive FR treatment and the FR treated lyocell fibres are rendered low-fibrillating e.g. whereby at least some of the hydroxyl groups are cross-linked with a reactant resin.

Claims

1. A flame retardant (FR) treated fabric, comprising yarns formed from a mixture of natural and/or synthetic fibres, the fabric further comprising FR treated lyocell fibres, wherein the FR treatment is a non-cellulose-reactive FR treatment and the FR treated lyocell fibres are rendered low-fibrillating.

2. The fabric of claim 1, wherein the fabric is a woven fabric comprising warp yarns and weft yarns.

3. The fabric of claim 1, wherein the natural fibres comprise cotton.

4. The fabric of claim 1, wherein the synthetic fibres comprise polyester, polyamide and/or aramid.

5. The fabric of claim 2, wherein the lyocell fibres are present in the warp yarns only.

6. The fabric according to claim 5, wherein the warp yarns comprise lyocell fibres, synthetic fibres and natural fibres.

7. The fabric of claim 5, wherein the weft yarns comprise a preponderance of natural fibres.

8. The fabric of claim 1, woven as a twill weave.

9. The fabric of claim 1, further comprising an anti-fibrillation finish.

10. The fabric of claim 1, further comprising a water and/or oil repellent finish.

11. The fabric of claim 1, further comprising antistatic fibres.

12. The fabric according to claim 2, comprising in the warp: 40-60 wt % lyocell, 15-35 wt % cotton; and 15-35 wt % recycled polyester; and in the weft: 70-99 wt % cotton, and 1-20 wt % recycled polyester.

13. The fabric of claim 1, wherein the fabric is durable to laundering at least 50x according to ISO 15797 and retains at least one or more of the following properties: a color retention score of greater than 2 or greater than 3 according to the greyscale comparison of ISO 105-A02; exceed the ignition to surface requirement of ISO11612 according to the test procedure of ISO15025 (2000) exceed the bottom edge ignition requirement of ISO11612 according to the test procedure of ISO15025 (2000); tear strength greater than 10N according to ISO13937-2 (2000); and tensile strength greater than 300N according to ISO13934-1 (2013).

14. The fabric of claim 1, wherein the fabric has abrasion resistance to more than 15 000 cycles, according to the Martindale Method and fulfilling ISO 12947-2 for an applied force of 12 KPa.

15. The fabric of claim 1, wherein the non-cellulose-reactive FR treatment comprises a THP salt.

16. A method of producing a flame retardant fabric comprising yarns including a mixture of natural and/or synthetic fibres and lyocell fibres having accessible hydroxyl groups, the method comprising first subjecting the fabric to a non-cellulose-reactive FR treatment and subsequently finishing the fabric by application of a resin to stabilise fibrillation of the lyocell.

17. The method of claim 16, comprising constructing the fabric by weaving the yarns with a warp yarn and a weft yarn.

18. The method of claim 17, wherein the lyocell fibres are present in the warp yarns only.

19. The method of claim 16, wherein the FR treatment is a THP based process.

20. The method of claim 16, wherein finishing the fabric by application of a resin, comprises cross-linking the resin.

21. The method of claim 16, wherein finishing further comprises a water and/or oil repellent treatment.

22. The method of claim 16, wherein, prior to subjecting the fabric to the FR treatment, the fabric is pre-treated by one or more process selected from the group consisting of: desizing, scouring, bleaching, mercerising, dying, including reactive and non-reactive dyes.

23. The method of claim 16, wherein the yarns are spun yarns comprising an intimate mix of staple fibres.

24. A garment manufactured of the fabric of claim 1.

Description

DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS

[0059] By way of a non-limiting example, the below process steps from source to product are described.

[0060] The steps of an exemplary manufacturing process are described as follows. [0061] Initially the staple fibres are formed into yarns by spinning. [0062] These yarns are then woven to greige cloth according to the desired and optimal specification. [0063] The greige cloth is inspected. [0064] There is a pre-treatment comprising desizing, scouring and bleaching. [0065] In a further pre-treatment step the cotton and lyocell are mercerised. [0066] The fabric is then dyed in a continuous dye process including dyeing and fixing. [0067] The cloth is then checked for colour deficiencies before entering the finishing process line. [0068] One or two FR treatment steps can be performed involving impregnation of the fabric and ammonia curing. [0069] The fabric is mechanically softened in an aero-tumbler to become more flexible. [0070] The product is stretched onto a tenter frame and treated with resin to prevent fibrillation. [0071] The fabric is subsequently heat treated to cross link the applied resin. [0072] A further finish is applied to obtain oil and water repellence. [0073] The product is treated with heat/annealed [0074] The fabric is Sanforized to reduce shrinkage. [0075] Quality control then occurs. [0076] This is followed by packaging and shipping to a clothing manufacturer where it is shaped for a specific use such as a specific workplace uniform.

[0077] The staple fibres which are formed into the yarns include cotton, Lyocell and recycled polyester. Cotton is a natural fibre that provides comfort and better moisture management than synthetic fibres. Cotton is the traditionally used fibre for FR-treated fabrics.

[0078] Lyocell is a synthetic cellulosic fibre. Other alternative cellulose based cotton alternatives exist such as Livaeco?, Birla Modal?, Birla Excel?, Birla Viscose? and Birla Spunshades? provided by Birla Cellulose. Lyocell is an industrial and launderable fibre which loses strength in the wet state. Lyocell in fact has a strength similar to cotton in the wet state and is more sustainable than cotton. Compared to cotton, the water usage of Lyocell is 95% less than of cotton. Lyocell is more comfortable than cotton with better moisture management and is generally smoother to the skin. It is however a fibrillating fibre; for example as in the wet state water penetrates inside the fibrillar bundles causing exposure of fibrils at the fibre surface. The rate of fibrillation increases with increased pH and increased temperature.

[0079] (Recycled) polyester can be mechanically or chemically recycled. Polyester is used in the FR-treated fabric to increase durability as it a relatively stronger material, however it is also heavier than cellulose based fabrics. Polyester cannot be made flame retardant with Proban chemistry. Mechanical recycled polyester can be used to improve sustainability. Use of recycled polyester provides an energy consumption reduction by 45% in comparison to use of virgin polyester, and has a water consumption reduction of nearly 20% in comparison to virgin polyester. The greenhouse gas emissions are reduced over 30% in comparison to virgin Polyester.

[0080] For the exemplary EG 9600 fabric, yarns were spun using the following staple fibres: [0081] Cotton (middling) [0082] Count 3,8-4,4 Micronair [0083] Length 27 mm [0084] Tenacity 26-30 cN/tex [0085] Tencel Lyocell Standard [0086] Count 1.25 dtex [0087] Length 38 mm [0088] Tenacity 38 cN/tex [0089] Tenacity wet 31 cN/tex [0090] Repreve recycled Polyester [0091] Count 1.3 dtex [0092] Length 38 mm [0093] Tenacity 59 cN/tex [0094] Nega-Stat? P190 [0095] Count 39/6 dtex [0096] Length=filament

[0097] An exemplary formulation of the fabric yarns is: [0098] Warp Yarn: [0099] 50% Lyocell; [0100] 25% Cotton; and [0101] 25% Recycled polyester. [0102] Weft Yarn: [0103] 90% Cotton; and [0104] 10% Recycled polyester. [0105] AS twisted Yarn: [0106] 75% Cotton; [0107] 8% Recycled polyester. [0108] 17% Negastat filament

[0109] The EC9600 fabric is woven in a 2/1 twill weave with the above warp and weft yarns. An anti-static yarn is included at a spacing of every 1:20 in the weft direction. The overall weight percentages of the respective fibres in the final fabric are: [0110] 50% Cotton; [0111] 30% Lyocell; [0112] 19% Recycled polyester. [0113] 1% Negastat filament

[0114] After a single pass THP treatment, the fabric was measured to have the following flame retardant characteristic values:

[0115] Amount of THP is measured by P, N analysis with the following results:

TABLE-US-00001 EG 9600: P 2.1% N 1.7% Traditional cotton product: P 2.9% N 1.9%.

[0116] Fabric is after FR-treatment still vulnerable to fibrillation. Finishing the fabric after FR-treatment with a suitable resin prevents fibrillation of lyocell in the product. The resin is applied in a foulard process and the application process includes water removal by pressing and heating, followed by thermal treatment for cross linking the resin. The term non-fibrillating as used herein will be understood to mean substantially non-fibrillating, and to be exchangeable with low-fibrillating. The application of a non-fibrillation resin provides a fabric having a reduced fibrillation compared to that in its virgin state.

[0117] A second finish is required to make the fabric water- and/or oil repellent finish through fluorocarbon resin (FC) to meet ISO 13034. The resin and the FC may be combined in one bath or, to improve the fibrillation and prevent loss of colour, the resin and FC finish may be applied after each other in a 2-step process. This 2-step process reduces the fibrillation after laundering. Further improvement is to cross-link the resin first before applying the FC finish.

[0118] Laundering according to the standard ISO 15797, 750C, j requirements is possible and results in reduced and homogeneous fibrillation. The fabric remains durable even up to 50 of the rigorous launders according ISO 15797, 750C, j.

[0119] The final product has the following advantages: [0120] 50% green materials, [0121] durable and sustainable, [0122] 28% lower water footprint than traditional FR-treated fabric, [0123] 10% lower CO2 footprint than traditional FR-treated fabric, [0124] Ultra-soft with breathability thanks to lyocell, [0125] Low water vapour resistance (breathability) and good short-time vapour absorbency, [0126] Better performance than traditional FR-treated fabric, [0127] Traditional FR-treated cotton fabrics feel stiff and sturdy, the EG9600 feels supple and soft to the skin, [0128] FR performance equal to traditional FR-treated cotton fabrics, [0129] Low pilling.

[0130] Three batches of the improved FR fabric were tested and the measured properties after the final finish are shown to be repeatable and in accordance with the technical specifications with details as follows:

TABLE-US-00002 Improved FR Fabric EG9600 Test 1 Test 2 Test 3 Weight g/m2 313 335 327 Pilling note 4 4 4 Tensile N 1514 ? 747 1336 ? 705 1241 ? 637 strength intial Tensile N 1183 ? 785 1088 ? 545 1030 ? 535 strength after 25x wash Tensile N 992 ? 799 strength after 50x wash Tear N 30.4 ? 25.2 32.8 ? 29.3 30.9 ? 27.5 strength intial Tear N 20.2 ? 21.3 25.8 ? 21.7 23.8 ? 21.3 strength after 25x wash Tear N 16.2 ? 17.4 strength after 50x wash Ignition to sec Pass Pass surface initial Ignition to sec Pass Pass surface after 50x wash Ignition to sec Pass Pass edge initial Ignition to sec Pass Pass edge after 50x wash

[0131] The technical specifications of the fabric of the invention are comparable and commensurate with the standard FR fabric and an alternative inherently flame retardant fabric known as Modal/Tencel? in terms of properties. The improved FR fabric of the invention further has improved comfort and reduced carbon footprint. Comparison of the technical specifications is as follows:

TABLE-US-00003 Standard Modac/ Improved Test Unit FR fabric Tencel? FR fabric Composition by 74/25/1% 54/45/1% 50/30/19/1% wt % Co/Pes/AS PPAN/CV/AS Co/CV/rPes/AS Construction Twill 2/1 S Twill 2/1 Z Twill 2/1 S Finish FR-treated Inherently FR FR-treated Weight g/m2 320 300 320 Pilling min. 4-5 4 4 Tensile strength N 1400 ? 650 950 ? 800 1300 ? 650 Tear strength N 23 ? 20 22 ? 22 30 ? 25 Ignition to sec Pass Pass Pass surface Ignition to edge sec Pass Pass Pass