Flame retardant and fabric softening treatment of textile materials

Abstract: A one-pack composition conferring flame-retardant and fabric-softening properties on fabrics comprises a THP⁺ salt, an organic nitrogen compound (eg urea) and a hydroxyl-reactive organic compound having 12 or more carbon atoms. Preferred examples of such compounds include C₁₂ amine, C₁₈ amine and tallow amine (viz a C₁₆ / C₁₈ / C₂₀ amine mixture).

Description: This invention relates to a composition adapted to confer flame-retardant and fabric-softening properties on a textile material, to a method for making said composition and to a fabric treated with said composition. 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 (THP + ) 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. Our United Kingdom Specification No. GB-A-2271787 discloses the addition of one or more protonated and neutralized amines (for example amine acetates) to the impregnation solution. This addition has been found to increase the efficiency of fixation of the phosphonium compound within the fibres, and to improve uniform distribution of the phosphonium compound in the system, which in turn has been found to lead to improved flame-retardant and increased water-repellant properties. Our United Kingdom Specification No. GB-A-2040299 discloses the addition of an inorganic base or a C 1 -C 4 tertiary amine base to the THP - compound, before condensation with urea. However, the aforementioned GB-A-2040299 does not address the question of the softness (drape) of the textile material when treated with the product of this disclosure. FR-A-2304712 and GB-A-1453296 also provide for the treatment of fabrics and textiles to render them flame-retardant. We have now found that the addition, to an aqueous mixture of a THP + salt and an organic nitrogen compound, of one or more aliphatic amines which include 12 or more carbon atoms, before reacting all the ingredients to bring about condensation of the THP + salt and the organic nitrogen compound, leads to the formation of a composition which, when used to treat textile materials according to the aforesaid PROBAN process, confers on the textile materials not only flame-retardant properties but also enhanced fabric-softening properties. Accordingly, the present invention provides a composition adapted to confer flame-retardant and fabric-softening properties on a textile material, characterised in that said composition comprises a stable, 60% aqueous solution of the product obtained by the reaction of (a) a tetrakis (hydroxyorgano) phosphonium (THP + ) salt; (b) an organic nitrogen compound selected from the group consisting of urea and thiourea; and (c) an aliphatic, amine having 12 or more carbon atoms and selected from the group n -dodecylamine (C 12 H 25 NH 2 ), n -octadecylamine (C 18 H 37 NH 2 ) and tallow amine [comprising n -hexadecylamine (C 16 H 33 H 2 ), n -octadecylamine (C 18 H 37 NH 2 ), and n -eicosylamine (C 20 H 41 NH 2 )] and wherein the molar ratio of the THP + salt (a) to the sum of the molar ratios of the organic nitrogen compound (b) and the amine (c), i.e. a:(b+c), is in the range 4:1 to 1.5:1. The present invention also provides a textile material comprising the composition described in the immediately-preceding paragraph. The present invention further provides a method for making the aforesaid composition, in which the method is characterised by the following stages: (i) placing the THP + salt (a) in a vessel and adjusting its pH to about 6.0 by the addition of an inorganic base; (ii) dissolving in the THP + salt/base solution the organic nitrogen compound (b) ; (iii) adding the amine (c) to the mixture [(a) + (b)]; (iv) maintaining the mixture [(a) + (b) + (c)] at reflux temperature for 3 to 4 hours until all the amine has disappeared, to bring about the formation of a condensation product between (a) and (b); (v) cooling the product; and (vi) adding sufficient water to the product to make a stable 60% aqueous solution of said product. The THP + salt (a) is preferably tetrakis (hydroxymethyl) phosphonium chloride (THPC) or tetrakis (hydroxymethyl) phosphonium sulphate (THPS). The molar ratio a:b:c is preferably in the range (4 to 1.5): (0.95 to 0.75): (0.25 to 0.05). For example, the molar ratio a:b:c may be any of the following: 4 0.95 0.05 3.5 0.95 0.05 3 0.95 0.05 2.5 0.95 0.05 2.5 0.9 0.1 2.5 0.75 0.25 2.0 0.95 0.05 2 0.9 0.1 or 1.5 0.95 0.05 The textile material may comprise substantially 100% cellulosic fibres (e.g. cotton, linen, jute, hessian or regenerated cellulosic material). Alternatively, the textile material may comprise both cellulosic fibres and non-cellulosic fibres. The non-cellulosic fibres may be, for example, wool or silk fibres or they may comprise synthetic fibres such as polyester, polyamide, acrylic or aramid fibres. The textile material may comprise, for example, 60% cotton fibres and 40% polyester fibres. In the method of the present invention, the inorganic base used in stage (i) may be, for example, sodium hydroxide or potassium hydroxide. Stage (iv) of the method may be carried out at atmospheric pressure or at a pressure higher than atmospheric, e.g. around 1.25 bar. Although it is not intended that the present invention be construed with respect to any particular theory, it is believed that the adjustment of the pH of the THP + salt to about 6.0 may render the salt more reactive towards the organic nitrogen compound. It is also believed that the demonstrably softer handle (drape) of the treated textile material may in part result from a reduced degree of cross-linking of the THP + salt/compound (c) condensate on to the material and/or from the presence of compound (c) in the chain. It is further believed that the treatment of textile materials according to the present invention may lead to an improvement in tear-strength and in resistance to abrasion. The present invention will be illustrated by way of the following Examples: Example 1 To a two-litre resin pot fitted with a condenser was added 1400 grams of tetrakis (hydroxymethyl) phosphonium chloride (THPC). The pH was adjusted to about 6 by adding 75 grams of a 50% potassium hydroxide solution. 132 grams of urea was introduced to the resin pot, and was allowed to dissolve while stirring. 38 grams of n-octadecylamine (available as ARMEEN* HTD) was introduced to the pot, and the temperature was raised to reflux. The mixture was kept at the reflux temperature for 3-4 hours until all the amine had disappeared. Heating was stopped, and water was added to make a 60% solution. The molar ratio of THPC: urea: n -octadecylamine was 2.5:0.95:0.05. A 100% cotton fabric of weight 280 g/m2 was padded with the above liquor to a 40% PROBAN* add-on, and processed according to the known PROBAN* process. The finished fabric had a dry add-on of 18.5% condensation product. The fabric processed with the above liquor was found to contain 2.75% P and 2.38% N, and passed the German (a), French (b), and British (c) FR tests, both before and after a 40 wash cycle at 93°C. Notes to Example 1 :- * The words ARMEEN and PROBAN are Registered Trade Marks. (a) DIN 66083 s-b (b) NFG 07-184 (c) BS 6249 Examples 2 to 6 The process of Example 1 was repeated and the quantities and results are shown in TABLE 1 (below): Ex. No. (a) THPC (g) 50% KOH (g) (b) Urea (g) (c) Amine (g) Molar ratio (a:b:c) Dry add-on: (%) Processed fabric content of: P (%) N (%) 2 1190 60 108 48 2.5:0.75:0.25 17.6 2.6 2.25 3 1428 75 171 36 2:0.95:0.25 19 2.77 2.55 4 1190 60 108 48 2.5:0.9:0.1 17.6 2.6 2.25 5 1428 75 162 72 2:0.9:0.1 19 2.6 2.44 6 1190 101 108 18.5 2.5:0.9:0.1 - 2.96 2.52 All the fabrics in Examples 2 to 6 (above) passed the flame-retardancy tests listed in Example 1. Examples 7 to 10 The process of Example 1 was again repeated, but these Examples only related to the preparation of the flame-retardant composition and not to its use on textile materials. The quantities are shown in TABLE 2 (below): Ex. No. (a) THPC (g) 50% KOH (g) (b) Urea (g) (c) Amine (g) Molar Ratio (a:b:c) Notes 7 1190 60 95 20 3:0.95:0.05 8 1190 60 71 15 4:0.95:0.05 9 1190 60 81.4 17 3.5:0.95:0.05 10 1074 60 171 36 1.5:0.95:0.05 Formed a polymeric gel The fabrics treated with the products of Examples 1 to 6 (above) showed greatly improved fabric handle and drape when compared to fabrics treated with a formulation according to the aforesaid GB-A-2040299. Examples 11 to 15 Example 1 was repeated using a molar ratio of THPC: Urea: Amine of 3: 0.95: 0.05 under the pressures, temperatures, and times shown TABLE 3 (below) : Example Temperature oc Pressure Bar Time min 11 105-108 Atmospheric 180 12 110 0.5 150 13 130 1.25 20 14 130 1.25 20 15 130 1.25 20 A 100% cotton fabric of weight 280 g/m 2 was processed using the aforesaid product. The processed fabric was found to have a phosphorus and nitrogen content of 3 and 2.5% respectively, and passed the German, French, British, and the new European Pr EN 533 flame-retardancy tests after 40 washes at 93°. Examples 16 to 20 Example 11 was repeated using the fabrics shown in TABLE 4 (below): Example Fabric Composition % Construction Fabric Weight g/m 2 Cotton PET 16 100 0 Twill 280 17 100 0 Plain 155 18 100 0 Plain 185 (pigment printed) 19 75 25 Twill 255 20 65 35 Twill 280 The treated fabrics passed the German, French, British, and the new European Pr EN 533 flame-retardancy standards after the required durability washes. Table 5 (below) shows the P&N results before and after the durability wash. Example P&N% Content (as finished) P&N% Content (after wash) P% N% P% N% 16 3.05 2.46 2.84 2.26 17 4.55 3.65 - - 18 2.98 2.45 2.10 1.63 19 3.02 2.46 3.01 2.24 20 3.49 2.81 2.97 2.42

Claims: A composition adapted to confer flame-retardant and fabric-softening properties on a textile material, characterised in that said composition comprises a stable, 60% aqueous solution of the product obtained by the reaction of: (a) a tetrakis (hydroxyorgano) phosphonium (THP + ) salt; (b) an organic nitrogen compound selected from the group consisting of urea and thiourea; and (c) an aliphatic amine having 12 or more carbon atoms and selected from the group consisting of n -dodecylamine (C 12 H 25 NH 2 ), n -octadecylamine (C 18 H 37 NH 2 ) and tallow amine [comprising n -hexadecylamine (C 16 H 33 H 2 ), n -octadecylamine (C 18 H 37 NH 2 ), and n -eicosylamine (C 20 H 41 NH 2 )] wherein the molar ratio of the THP + salt (a) to the sum of the molar ratios of the organic nitrogen compound (b) and the amine (c), i.e. a:(b+c), is in the range 4:1 to 1.5:1. A composition according to Claim 1, characterised in that the THP + salt (a) is tetrakis (hydroxymethyl) phosphonium chloride (THPC) or tetrakis (hydroxymethly) phosphonium sulphate (THPS). A composition according to Claim 1 or 2, characterised in that the molar ratio a:b:c is in the range (4 to 1.5):(0.95 to 0.75):(0.25 to 0.05). A textile material comprising a composition according to any one of the preceding claims. A textile material according to Claim 4, characterised in that it comprises substantially 100% cellulosic fibres. A textile material according to Claim 5, characterised in that the fibres are of cotton, linen, jute, hessian or a regenerated cellulosic material. A textile material according to Claim 4, characterised in that it comprises cotton fibres and wool or silk fibres. A textile material according to Claim 4, characterised in that it comprises cotton fibres and polyester, polyamide, acrylic or aramid fibres. A textile material according to Claim 8, characterised in that it comprises 60% cotton fibres and 40% polyester fibres. A method for making a composition according to any one of Claims 1 to 3, characterised in that the method comprises the following stages: (i) placing the THP + salt (a) in a vessel and adjusting its pH to about 6.0 by the addition of an inorganic base; (ii) dissolving in the THP + salt/base solution the organic nitrogen compound (b); (iii) adding the amine (c) to the mixture [(a) + (b)]; (iv) maintaining the mixture [(a) + (b) + (c)] at reflux temperature for 3 to 4 hours until all the amine has disappeared, to bring about the formation of a condensation product between (a) and (b); (v) cooling the product; and (vi) adding sufficient water to the product to make a stable 60% aqueous solution of said product. A method according to Claim 10, characterised in that the inorganic base used in stage (i) is sodium hydroxide or potassium hydroxide.

Inventors: LEI XIAO PING, ZAKIKHANI MOHSEN, LEI, XIAO PING, ZAKIKHANI, MOHSEN
Applicants: RHODIA CONS SPEC LTD, RHODIA CONSUMER SPECIALTIES LIMITED
Application year: 1995
Main classification: D06M15
IPC codes: D06M13, D06M101, D06M15, D01F1