GB2084622A - Flameproofing compositions - Google Patents

Abstract

A flameproofing composition comprising a halogenated alkyl or aryl phosphate and an emulsifying agent for emulsifying the phosphate in an aqueous diluent and optionally a carrier and diluent. The preferred phosphate is tris (1, 3-dichloropropyl) phosphate. This composition is useful for flameproofing leather.

Description

SPECIFICATION Flameproofing compositions The invention relates to flameproofing composi tionsforfiameproofing such material as natural and synthetic leather, particularly natural leather, with halogenated alkyl or aryl phosphates.

Recent attention has been brought to bear on the problem of increasing the safety factor in flamep roofing of upholstered articles such as domestic furniture or aircraft seatings, particularly where the upholstery covers combustible polyurethane and is likely to be contacted with smouldering or burning material such as lighted cigarettes.

Recently devised tests for measuring the effectiveness of flameproofing of upholstery materials are described in the British Standard Association's Draft for Development DD 58 of 1978, and include the "smouldering cigarette" test, in which a lit cigarette is placed in contact with the material and allowed to burn until it extinguishes naturally. To pass the test, the upholstered material must not show progressive smouldering after the cigarette has ceased to burn.

Vegetable tanned leather is seldom used for upholstery for, although it has good fireproofing properties, the leather is hard and tends to be heavierthan chrome tanned leather. Chrome tanned leather is particularly useful in upholstery because of its soft handle and light weight but it has unsatisfactory fireproofing properties. Attempts have been made to impregnate chrome leather with borax-type materials but the handle and appearance ofthe resultant leather is affected in such a way as to renderthe leather stiff, raspy and hard and therefore unsuitable for furniture. Soft handle and light weight are particularly important features for leather used in aircraft seat upholstery.

Other leather articles for which improved flameproofing would be desirable include leather protective clothing, for example that worn by motor cyclists, and industrial leather gloves.

According to the invention there is provided a flameproofing composition comprising a halogenated alkyl or aryl phosphate and an emulsifying agent capable of emulsifying the phosphate in an aqueous diluent. Optionally a carrier and optionally a diluent selected from water and water-miscible organic solvents may be present.

Preferably the flameproofing composition comprises 5 to 95% halogenated alkyl or aryl phosphate, 95 to 5% emulsifying agent plus optionally a carrier and 0 - 30% diluent. Alternatively preferred the composition comprises 20 to 50% phosphate, 7 to 30% emulsifying agent and optionally up to 55% diluent.

Further according to the invention there is provided a process for improving the flame retardency of leather comprising applying a flame-retardant effective amount of a halogenated alkyl or aryl phosphate to leather. Preferably at least 5%, more preferably at least 10% (by dry weight of the leather) is applied. The phosphate can be applied to the leather by treating the leather in a bath containing the flameproofing composition according to the invention described above, diluted with further diluent, e.g. water, where necessary.

Alternatively the halogenated phosphate can be applied to leather by immersing in or spraying with a solution of a halogenated alkyl or aryl phosphate in a solvent selected from lower alkyl alcohols, lower alkyl esters and lower alkyl ketones preferably so that at least 5% (by dry weight of leather treated) remains in the leather.

Preferably the halogenated phosphate used in a composition or process according to the invention is a tris (dihalogenated lower alkyl) phosphate where the lower alkyl groups are the same or different and are C1-4 alkyl. More preferably the phosphate is tris(1,3-dichloropropyl) phosphate.

Preferred emulsifying agents are anionic in nature and include aliphatic sulphonates, for example Sandozin NEA (a trade mark), a modified alkyl polyglycol (for example sulphonated lauryl alcohol 2Et0), car boxylated surfactants, for example Sandopan 2N (a trade mark), alkaryl sulphonic acids, for example dodecyl benzene sulphonic acid or fatty acid soaps, for example oleic acid soaps. More preferably mixtures of anionic emulsifying agents are used.

Because the phosphate is extremely difficult to emulsify alone, it may be necessary to use a carrier to facilitate the emulsification process. Such a carrier is an organic liquid which is a solvent for the phosphate and is substantially immiscible with water.

Depending upon its volatility, the carrier may be removed by drying after treatment, or may remain in the leather, whereit may contribute to its flame retardant properties. Preferred carriers are chlorinated hydrocarbons, more preferably polychlorinated paraffins e.g. Cerechlor 50 LV (a trade mark).

One preferred flameproofing composition comprises approximately equal weights of phosphate and carrier, more preferably 30 - 35% phosphate, 30 35% carrier, 10 - 20% emulsifying agent and 10 to 30% diluent.

Alternatively the phosphate may be emulsified by adding to the phosphate an alkaryl sulphonic acid, neutralising with base and then adding water containing a thickening agent such as polyvinyl alcohol.

The emulsion may also be formed by using, instead of the sulphonate, a soap of a fatty acid. A preferred range for the composition would then be 30-35% phosphonate, 5 to 15% emulsifying agent, 0.5 to 2% thickener and up to 55% water.

The diluent is preferably water, but may also be a water-miscible or at least partly water-soluble organic solvent for example a lower alcohol, glycol, ester or ketone. The solvent should preferably be at least as volatile as water, so that flammable residues will not be left in the leather. Mixtures of water and organic solvents may also be used as diluent.

When a composition according to the invention is used in the treatment of leather, it is preferably mixed with water so as to give an emulsion of the phosphate (plus carrier if present) in water. The amount of water with which it is mixed is not critical and will depend upon the nature of the leather to be treated, and the equipment used. Typically, however, the composition may be diluted with from 1 to 10, preferably 2 to 5 times its own weight of water.

In the application process, the leather is preferably contacted with the emulsion obtained by diluting the composition, and the emulsion is then acidified, e.g.

with formic acid, until the anionic emulsifiers are converted to their protonated (free acid) forms. At this point they no longerfunction as emulsifiers, the emulsion breaks, and the separated phosphate and carrier are taken up by the leather. The application process according to the invention can be incorporated into an anionic dyeing process or a fat liquoring process. Such an anionic dyeing process or fat liquoring process comprises treating the leather at a pH of 7 and progressively reducing the pH to pH 3.5 to 4.0 for exhaustion of the dye or fat liquor onto leather. Although it is preferable to include a composition according to the invention in an anionic system it is envisaged that the composition can be used in cationic, amphoteric and non-ionic systems, albeit less effectively.

A particular substrate onto which the phosphate can be applied is chrome tanned natural leather.

The invention also provides leather, preferably chrome-tanned leather, containing at least 5%, preferably at least 10% by dry weight of the leather of a halogenated alkyl or aryl phosphate.

The starting material tris(1,3dichloropropyl)phosphate is known and can be made according to known methods.

The invention will now be illustrated with reference to the accompanying Examples in which all temperatures are in degrees Centigrade and all percentages are in percentages by weight unless indicated to the contrary.

Example 1 An emulsion of tris(1 3-dich loropropyl )phosphate is prepared with the following composition: 33% chlorinated paraffin (Cereclor 50LV, a trade mark) 34% tris(1 ,3-dich loropropyl )phosphate 12% Sandozin NEA (a trade mark) 3% Sandopan 2N conc. (a trade mark) 17% demineralised water 1% hexylene glycol 3 Parts of the above composition are diluted with 10 parts water and heated to 50-60"C. A sample of chrome tanned leather (10 parts dry weight at 20"C) is added to the bath. After 2 hours formic acid is added to reduce the pH of the liquor to 3.5. 45 Minutes are allowed for this adjustment and exhaustion appears visibly satisfactory.After setting out and drying in conventional manner, tests show that the treatment is effective in the smouldering cigarette test, the amount of tris(1,3dichloropropyl)phosphate itself used being 10% calculated on the dryweight of leathertreated.

The above treatment can form a part of a normal anion active dyeing or fatliquoring process comprising treating the leather at a pH of 7 and progressively reducing the pH to pH 3.5 - 4.0 for exhaustion of an anionic dye or fatliquor onto the leather.

Example 2 An emulsion of tris(1 ,3-dichloropropyl)phosphate is prepared by mixing 35 parts of tris(1,3dichloropropyl) phosphate and 7.5 to 9 parts dodecyl benzene sulphonic acid, neutralising this with aqueous sodium hydroxide solution and then, while stirring adding dropwise a solution of 52 to 53 parts deminieralised water and 1 part polyvinyl alcohol.

The emulsion so formed is applied to leather according to the procedure of Example 1.

Claims (20)

1. Aflameproofing composition comprising a halogenated alkyl or aryl phosphate and an emulsifying agent capable of emulsifying the phosphate in an aqueous diluent.

2. Aflameproofing composition as claimed in Claim 1 including an aqueous diluent.

3. A flameproofing composition as claimed in Claim 2 in which the diluent is water together with a polyvinyl alcohol.

4. Aflameproofing composition as claimed in Claim 1 or Claim 2 including a carrier.

5. Aflameproofing composition as claimed in Claim 4 in which the carrier is a chlorinated hydrocarbon.

6. Aflameproofing composition as claimed in Claim 5 in which the carrier is a polychlorinated paraffin.

7. Aflameproofing composition as claimed in any one of the preceding claims in which 5 to 95% halogenated alkyl or aryl phosphate, 95 to 5% emulsifying agent (optionally with a carrier) and 0 to 30% diluent is present.

8. Aflameproofing composition as claimed in any one of Claims 1 to 6 in which 20 to 50% phosphate, 10 to 30% emulsifying agent, optionally 20 to 50% carrier and up to 55% diluent is present.

9. A flameproofing composition as claimed in any one of the preceding claims in which the phosphate is tris(dihalogenated lower alkyl)phosphate.

10. Aflameproofing composition as claimed in Claim 9 in which the phosphate is tris(1,3dichloropropyl)phosphate.

11. A flameproofing composition as claimed in any one of the preceding claims in which the emulsifying agent is selected from an aliphatic sulphonate, a modified alkyl glycol, a carboxylated surfactant, an alkaryl sulphonate or a fatty acid soap.

12. A process for improving the flame retardancy of a leather substrate.comprising applying to the substrate a flameproof effective amount of a halogenated alkyl or aryl phosphate.

13. A process as claimed in Claim 12 comprising applying to the substrate a flameproof effective amount of a composition as claimed in any one of Claims 1 to 11.

14. A process as claimed in Claim 13 comprising applying at least 5%, by dry weight of substrate to be treated, of the phosphate.

15. A process as claimed in Claim 14 comprising applying at least 10% of the phosphate.

16. A process as claimed in any one of Claims 12 to 15 in which the leather substrate is natural leather.

17. Leatherwhen treated with a halogenated alkyl or aryl phosphate.

18. Chrome leather when treated with a composition as claimed in any one of Claims 1 to 11.

19. A process substantially as herein described with reference to Example 1 oF Example 2 fortreating a leather substrate.

20. A composition substantially as hereinbefore described with reference to Example 1 or Example 2.