Flame-retardant and water-resistant treatment of fabrics

Abstract: In a method for the flame-retardant treatment of fabrics by impregnation with a condensate of a tetrakis (hydroxyorgano) phosphonium salt and, e.g., urea, the addition of one or more protonated and neutralized amines to the impregnation solution increases the efficiency of fixation of the phosphonium salt within the fibres, improves its uniform distribution within the system and leads to improved flame-retardant and water-resistant properties.

Description: This invention relates to an improved method of treating fabrics to impart flame-retardant and water-resistant properties thereto. A known process for the flame-retardant treatment of fabrics including cellulosic (e.g. cotton) fibres consists of impregnation of the fabric with an aqueous solution of a poly(hydroxyorgano) phosphonium compound, for example, a tetrakis (hydroxyorgano) phosphonium salt. Alternatively, the poly (hydroxyorgano) phosphonium compound may comprise a condensate with a nitrogen - containing compound such as urea. Following impregnation, the fabric is dried and then cured with ammonia to produce a cured, water-insoluble polymer which is mechanically fixed within the fibres of the fabric. After curing, the polymer is oxidised to convert trivalent phosphorus to pentavalent phosphorus and the fabric is washed and dried. Fabrics treated according to the aforesaid process and garments made from such treated fabrics are sold under the Registered Trade Mark PROBAN of Albright & Wilson Limited. It is also known from FR-A-2210692 to impregnate fabrics with a condensate of a tetrakis (hydroxyalkyl) phosphonium salt and an aliphatic amine. We have now found that the addition of one or more protonated and neutralized amines to the impregnation solution increases the efficiency of fixation of the phosphonium compound within the fibres, improves uniform distribution of the phosphonium compound in the system, and leads to improved flame-retardant and increased water-resistant properties. Accordingly, the present invention provides a method of treating fabrics to impart flame-retardant and water-resistant properties thereto, said method comprising impregnating the fabric with an aqueous solution including a precondensate of a tetrakis (hydroxyalkyl) phosphonium with urea, drying the impregnated fabric, curing the dried fabric with gaseous ammonia and oxidising the cured fabric with hydrogen peroxide, in which there is added to the impregnating solution one or more primary, secondary or tertiary aliphatic amines having from 12 to 20 carbon atoms, said amines having been protonated and neutralized prior to said addition. The concentration of protonated and neutralized amine in the impregnating solution is suitably in the range 0.05% to 3% by weight, preferably in the range 0.1% to 1% by weight, especially about 0.3% by weight. In a preferred embodiment of the present invention, the protonated and neutralized amine consists essentially of n -odadecylamine. In an alternative embodiment of the present invention, the protonated and neutralized amine comprises a mixture of primary aliphatic amines having from 16 to 18 carbon atoms. Suitably, the tetrakis (hydroxyalkyl) phosphonium (hereinafter THP) compound, is a [THP] + salt, eg, THP chloride. The amines are protonated and neutralized according to the present invention by means of a weak organic acid, for example acetic acid. The protonated and neutralized amine may therefore consist essentially of octadecylamine acetate. Suitably, the amines may be obtained in an already-protonated and neutralized state. Alternatively, the amines can simply be mixed with sufficient acetic acid to achieve protonation and neutralization and the so-treated amines added to the impregnation solution. The present invention will be illustrated, merely by way of example, as follows: The following fabrics were treated in accordance with the present invention: Sample Code A A satin fabric comprising 60% cotton fibres and 40% polyester fibres and having a weight of 280g/m 2 Sample Code B A twill fabric comprising 60% cotton fibres and 40% polyester fibres and having a weight of 245g/m 2 Sample Code C A twill fabric comprising 60% cotton fibres and 40% polyester fibres and having a weight of 315g/m 2 . Sample Code D A plain-weave, pigment-printed fabric comprising 100% cotton fibres and having a weight of 200g/m 2 The fabrics were impregnated with an aqueous solution containing the following percentages by weight of a precondensate of tetrakis (hydroxymethyl) phosphonium chloride and urea, together with protonated and neutralized amines in accordance with the present invention, the ratio of the phosphonium chloride to urea in the condensate being 2:1 molar: A: 42.25% by weight B: 42.25% by weight C: 39% by weight D: 32.5% by weight The impregnated fabrics were squeezed to a wet pick-up in the following ranges based upon the original weight of the fabric: A: 80% B: 80% C: 80% D: 90% The fabrics were then dried at 120 o C and kept overnight at ambient temperature to achieve a moisture content in the range 4 to 8 %, preferably 5 to 8%. The dried fabrics were cured with gaseous ammonia to cure the precondensate within the fibres of the fabrics, followed by oxidation with hydrogen peroxide, washing and drying. TABLE I (below) shows the results of testing for flame-retardant properties according to DIN 66083 s-b: TABLE II (below) shows the results of testing for flame-retardant properties according to NFG 07-184 and BS 6249. Sample Code NFP 07-184 (damaged area) cm 2 ---------------BS 6249-------------- (char length) mm Afterflame (sec) Afterglow (sec) A warp 25 50 0 0 weft 26 50 0 0 B warp 35 82 0 0 weft 31 62 0 0 C warp 36 40 0 0 weft 33 50 0 0 D warp 29 64 0 0 weft 24 53 0 0 The results of determination of phosphorus and nitrogen content of the fabrics after 40 washing cycles at 93 o C is shown in TABLE III (below). additive solid (%) after NH3 cure as finished after washing P% N% P% N% P% N% A: 0 (control) 3.66 3.92 2.87 2.64 2.50 2.40 0.3 3.61 3.96 3.46 2.23 3.33 3.01 B: 0 (control) 3.69 4.08 3.15 2.97 2.82 2.60 0.3 3.68 4.29 3.63 3.37 3.24 2.89 C: 0 (control) 3.33 3.40 3.09 2.75 2.89 2.51 0.3 3.42 3.98 3.33 3.14 3.12 2.87 D: 0 (control) 3.21 3.89 2.94 2.94 2.74 2.51 0.3 3.41 4.40 3.31 3.28 3.00 2.84 The water-resistance of fabrics treated according to the present invention was determined and the results are shown in TABLE IV below: Sample Water-resistance (cm water) Untreated fabric (control I) 4 Treatment without protonated amine (control II) 5 Treatment with protonated amine 16 The fabric used in the foregoing tests was Sample Code C (see above). In another example, the following fabrics were treated in accordance with the present invention: Sample Code C (As hereinbefore described). Sample Code E A twill fabric comprising 60% cotton fibres and 40% polyester fibres and having a weight of 240 g/m 2 . The fabrics were impregnated with an aqueous solution containing the following percentages by weight of a precondensate of tetrakis (hydroxymethyl) phosphonium chloride and urea, together with protonated and neutralized amines in accordance with the present invention, the ratio of the phosphonium chloride to urea in the condensate being 2:1 molar: C: 40.95% by weight E: 37.05% by weight The impregnated fabrics were squeezed to a wet pick-up in the following ranges based upon the original weight of the fabric: C: 77% E: 99% The fabrics were then dried at 120 o C to achieve a fabric moisture content of between 14-18%. The dried fabrics were cured with gaseous ammonia in the following manners: C1: In one step C2: In two stages, one after the other E1: In one step E2: In two stages, one after the other This was followed by oxidation with hydrogen peroxide, washing and drying. Table V (below) shows the results of testing for flame-retardant properties according to DIN 66083 s-b: Sample Code Direction of test Ignition time (sec) Afterflame (sec) Afterglow (sec) Char length (mm) C1 warp 3 1 0 7 15 0 0 110 3 1 0 9 15 0 0 70 weft 3 0 0 5 15 0 0 70 3 0 0 5 15 0 0 75 C2 warp 3 0 0 5 15 0 0 65 3 1 0 5 15 0 0 60 weft 3 1 0 7 15 0 0 60 3 1 0 5 15 0 0 55 E1 warp 3 1 0 11 15 0 0 65 3 2 0 11 15 0 0 70 weft 3 1 0 11 15 0 0 65 3 0 0 8 15 0 0 75 E2 warp 3 1 0 8 15 0 0 65 3 0 0 7 15 0 0 72 weft 3 0 0 5 15 0 0 70 3 1 0 8 15 0 0 85 Table VI (below) shows the results of testing for flame-retardant properties according to NFG 07-184. Sample Code Direction of test Damaged Area (cm 2 ) C1 warp 21 weft 23 C2 warp 21 weft 22 E1 warp 27 weft 25 E2 warp 24 weft 22 The results of determinations of the phosphorus and nitrogen content of the fabrics before and after 40 washing cycles at 90 o C with a detergent containing 5% perborate is shown in Table VII (below). Sample Code After NH 3 Cure As finished After washing P% N% P% N% P% N% C1 3.53 3.92 3.47 3.23 3.28 3.10 C2 3.52 4.42 3.53 3.39 3.53 3.43 E1 4.01 4.68 3.66 3.44 3.65 3.59 E2 3.98 5.00 3.86 3.70 3.85 3.76 In yet another example the fabrics, coded C and E, were padded with the standard mixture and dried at 120 o C to a fabric moisture content of between 9-12%. The fabrics were cured with gaseous ammonia in a one step manner, followed by heat curing at 130 o C. The fabrics were then oxidised with hydrogen peroxide, followed by washing and drying. (Sample Codes were designated as C3 and E3 respectively). The fabric (coded C) was also treated under the above conditions in large quantities in the plant (sample coded CM). Table VIII shows the results of testing for flame-retardant properties according to DIN 66083. Sample Code Direction of test Ignition time (sec) Afterflame (sec) Afterglow (sec) Char length (mm) C3 warp 3 0 0 5 15 0 0 90 3 0 0 5 15 0 0 95 weft 3 0 0 5 15 0 0 75 3 0 0 5 15 0 0 90 CM warp 3 1 0 5 15 0 0 110 3 0 0 5 15 0 0 76 weft 3 1 0 5 15 0 1 50 3 1 0 5 15 0 1 55 E3 warp 3 0 0 5 15 0 0 70 3 0 0 5 15 0 0 75 weft 3 0 0 5 15 0 0 70 3 0 0 5 15 0 0 98 Table IX (below) shows the results of testing for flame-retardant properties according to NFG 07-184. Sample Code Direction of test Damaged Area (cm 2 ) C3 warp 28 weft 26 CM warp 27 weft 25 E3 warp 27 weft 26 The results of determination of phosphorus and nitrogen content of the fabrics after 40 washing cycles at 93 o C is shown in Table X (below). Sample Code After heat Cure As finished After washing P% N% P% N% P% N% C3 3.82 4.04 3.54 3.21 3.31 2.91 CM 3.53 3.57 3.24 2.88 3.07 2.69 E3 4.10 4.50 3.73 3.62 3.43 3.18 Fabrics treated according to the present invention may suitably consist essentially of cellulosic fibres, e.g. cotton fibres. Alternatively, the fabrics may comprise both cellulosic and non-cellulosic fibres, for example polyamide fibres, acrylic fibres, aramid fibres, polyester fibres or polybenzimidazole fibres. Suitably, the maximum content of non-cellulosic fibres in such a fabric is 70%, e.g. the fabric may comprise 60% cotton fibres and 40% polyester fibres. A suitable weight range for the fabrics treated according to the present invention is from 0.05 to 1.0 kg/m 2 .

Claims: A method of treating fabrics to impart flame-retardant and water-resistant properties thereto, said method comprising impregnating the fabric with an aqueous solution including a precondensate of a tetrakis (hydroxyalkyl) phosphonium compound with urea, drying the impregnated fabric, curing the dried fabric with gaseous ammonia and oxidising the dured fabric with hydrogen peroxide, characterised in that there is added to the impregnating solution one or more primary, secondary or tertiary aliphatic amines having from 12 to 20 carbon atoms, said amines having been protonated and neutralized prior to said addition. A method according to Claim 1, characterised in that the concentration of said protonated and neutralized amine in said solution is in the range 0.05% to 3% by weight, preferably 0.1% to 1% by weight and especially about 0.3% by weight. A method according to Claim 1 or 2, characterised in that said protonated and neutralized amine consists essentially of n -octadecylamine. A method according to Claim 1 or 2, characterised in that said protonated and neutralized amine comprises a mixture of primary aliphatic amines having from 16 to 18 carbon atoms. A method according to any one of Claims 1 to 4, characterised in that the tetrakis (hydroxyalkyl) phosphonium compound is a tetrakis (hydroxymethyl) phosphonium salt, for example tetrakis (hydroxymethyl) phosphonium chloride. A method according to any one of the preceding claims, characterised in that the amines are protonated and neutralized by means of a weak organic acid, for example acetic acid. A method according to Claim 6, characterised in that said protonated and neutralized amine consists essentially of octadecylamine acetate.

Inventors: LEI XIAO PING, SPEAKE DAVID WILLIAM, ZAKIKHANI MOHSEN, LEI, XIAO PING, SPEAKE, DAVID WILLIAM, ZAKIKHANI, MOHSEN
Applicants: ALBRIGHT & WILSON UK LTD, ALBRIGHT & WILSON UK LIMITED
Application year: 1993
Main classification: D06M13
IPC codes: D06M13, D06M11, D06M101, D03D15, D06M15