GB1603123A

GB1603123A - Fire retardant formulation

Info

Publication number: GB1603123A
Application number: GB2091478A
Authority: GB
Original assignee: Thacker D A
Current assignee: Thacker D A
Priority date: 1978-05-31
Filing date: 1978-05-31
Publication date: 1981-11-18

Description

(54) FIRE RETARDANT FORMULATION (71) I, DEREK AUBREY THACKER, a British Subject, of Blue Seas, 47 Southdean Drive, Middleton-on-Sea, Rognor Regis, West Sussex, PO22 7TB, do hereby declare the invention for which I pray that a patent may be granted to me, and the method by which it is to be performed, to be particularly described in and by the following statement: The present invention relates to fire retardant formulations and particularly those suitable for the treatment of synthetic rather than natural materials.

Today a considerable proportion of furnishings, carpets, structural components, packaging materials and clothes contain a proportion of man-made or synthetic substances.

The reaction of such substances to heat is compound and progressive. The synthetic substance will flame and melt whilst generating more heat and propagating flame spread at an even greater rate. Under certain circumstances the molten synthetic substance will drop from suspended material and, still burning, set fire to materials below. With clothing, the molten material can adhere to skin and greatly aggravate the injury already caused. Due to the chemical composition of the synthetic material there is also the danger of the production of toxic fumes on pyrolysis.

Many various formulations have been tried for treating synthetic materials to reduce flame spread and the amount of char/melt with widely varying results, including the production of considerable amounts of toxic fumes when burnt, over and above those which would have been produced by the material alone before treatment.

As the treatment of a synthetic material can only affect the surface of the material as opposed to natural materials which can absorb the retardant, careful thought must be given to the possibility of dermatitis being caused by treated clothing. It must also be possible for operatives to be in regular contact with the retardant without any ill effect and, under conditions of pyrolysis, the retardant must not contribute to the toxic fumes present.

The present formulation is intended to provide "balanced" protection against flame spread and melt whilst meeting the health and hygiene requirements above.

In accordance with the present invention there is provided a flame-proofing and fire retardant composition comprising an aqueous solution of: (a) ammonium hydrogen sulphate, (b) ammonium dihydrogen phosphate, and (c) diammonium hydrogen phosphate The present invention also provides an anhydrous mixture which on dissolution in water yields a composition of the present invention.

Preferably the present compositions also include CHEMFLEX 3 and NATRIO PLUS, sodium hypochlorite and sodium chloride.

CHEMFLEX 3 is the trade name of a commercially-available product compounded by Norkem Supplies of Kings Lynn, Norfolk, and NATRIO PLUS is the trade name for a mixture of sodium hexafluorosilicate, sodium metasilicate, Sorensens phosphate and sodium stearate commercially produced by Arnot Blenders of Cheam, London.

Preferably, the ratio by weight of component (a) to component (b) is between 1 : 1.75 and 1: 2.25, desirably about 1: 2, whilst the ratio by weight of component (b) to component (c) is between 8:1 and 12: 1, desirably about 10: 1. When a hypochlorite salt is used, up to 0.01% is satisfactory with a weight ratio thereof to chloride salt, when present, of between 1: 8 and 1: 20.

Advantageously, a water-repellant additive e.g. sodium stearate, is present in an amount of up to 0.5% by weight, based on the weight of the composition. For synthetic material, it is preferred to include a binder, such as an alkali metal silicate, desirably a mixture of sodium hexafluorosilicate and sodium metasilicate in an amount of up to 1% by weight.

Disodium hydrogen phosphate may also be present.

Desirably an additional ammonium salt, e.g. ammonium sulphamate or ammonium metaborate, is present in a total amount of up to 4% by weight.

It is preferred to manufacture the present composition as a concentrate ready for dilution by the user, and in this case the following formulation has been found to possess a very good "balance" of properties for use on synthetic material: TABLE 1 Gramsl wt % wt % Substance Gallon solids total (a) ammonium hydrogen 1000.() 30.

phosphate 1000 (b) ammonium dihydrogen ) 7 phosphate 2018.44 60.57 (c) diammonium hydrogen phosphate 181.84) 3200.28 5.46 96.04 (d) CHEMFLEX 3 96.00 96.00 2.88 2.88 (e) NATRIO PLUS 20.00 20.00 0.60 0.60 (f) sodium hypochlorite) 16.00 16.00 0.48 0.48 (g) sodium chloride ) CHECK TOTALS 3332.28 3332.28 100 100 An aqueous mixture of 1% by weight sodium hypochlorite and 16.5% by weight sodium chloride is commercially available and this is the mixture referred to in Table 1 above.

For commercial reasons the present formulation is prepared from industrial grade starting materials and due to impurities time and care must be allowed for the removal of scum and sediments. The following scheme has been devised to ensure the production of the present formualtion as a stable solution: TABLE 2 COMPONENT DAY ADDED ACTION 1 (a) mix with preferably de-ionised water, raise to between 70 and 80"F. Agitate.

2 (b) mix, agitate, check for scum and/or sediment, 3 (c) mix, agitate, leave to stand, 4 - check for scum and/or sediment, 5 (d) mix, agitate, 6 (e) mix, agitate, check for scum and/or sediment, 7 (f) and (g) mix, agitate, reduce to ambient temperature, 7-11 - stand, 12-13 - final scum/sediment check, 14 - package for delivery.

To the completed retardant, one or more additives can be added before final packaging and delivery, depending on the particular field of application for the final formulation.

Suitable additives which have been found to be compatible with the present composition are described in detail below.

As mentioned previously, the formulation particularly described above has been found to have a very good "balance" of properties, and to be effective on items containing from 100% to about 25%, preferably 100% to 35% by weight of synthetic products, the remainder being natural products. If the amount of any one of the components is varied by more than 5%, it has been found that this "balance" is distrurbed in some way so that the final formulation is of more limited usefulness. A similar effect has been noted if the amount of more than one component is varied so that the total variation is greater than 5%.

The pH of the final solution also appears to be significant and whilst the above-described formulation has a pH of 2.5 variations of pH outside a range of 2.0 to 2.9 appear to be undesirable. If necessary the pH can be adjusted before packaging and delivery by using an appropriate acidic or alkaline solution.

The present formulation can be applied to the item to be protected by simple spray application or complete immersion. Conventional free air drying or careful forced air drying can be used to complete the treatment of the item.

A wide range of items can be treated with the present formulation, e.g. carpets, polystyrene mouldings or tiles, clothing made of synthetic fibres, expanded urethane foam as is often used in furniture, and expanded polystyrene, and in general any items containing up to about 20% by weight of natural products.

The "synthetic" products which appear to be significantly affected by the present formulation are those consisting of essentially non-absorbent, polymeric fibres, such as polyamides e.g. nylon, polyacrylonitriles, polyesters, etc.

For specific applications the following additives may be used in the present formulation.

Only small amounts need be employed, the actual amount depending, of course, on the particular material to be treated.

(i) Ammonium uranium fluoride, UO2(NH4)2F5. Where its use is allowed, this acts as a tracer so that the extent of treatment can be determined.

(ii) Ammonium zirconyl carbonate, (NH4)3ZrOH(CO3)3. Although toxic, this has good water proofing properties and so can be used externally e.g. on tents and outside woodwork.

(iii) Sodium hexaflurosilicate, Na2SiF6. This is a fixative designed to assist the retardant to adhere to a non-absorbent surface.

The following test results have been obtained using the present formulation: By Dupont International, Geneva: Time to catch Total flaming char length fire (secs) time (secs) (cm) NOMEX 920 (Registered Trade Mark) Fire Brigade Cloth Untreated 4 12 2 Treated - - 1 Polyester/Wool Overalls Untreated 3 28 3 Treated 3 14 10 By Donaghadee Carpets, N. Ireland: The material tested was Acrylan pile carpet on foam rubber back - test carried out in accordance with British Standard 4790:1972.

Untreated Burning time 1.90 min.

Smoking time 1.10 Radius of burnt pile 40 mm Radius of burnt foam 11 mm Treated Burning time 0.75 min.

Smoking time 1.05 Radius of burnt pile 40 mm Radius of burnt foam NIL - no damage.

In dermatitic tests, the solution of the present invention was found to be completely non-irritant to the skins of rabbits in accordance with the FDA Handbook test for primary skin irritation.

WHAT I CLAIM IS: 1. A flame-proofing and fire retardant composition comprising an aqueous solution of: (a) ammonium hydrogen sulphate, (b) ammonium dihydrogen phosphate, and (c) diammonium hydrogen phosphate 2. A composition as claimed in claim 1 wherein the ratio by weight of component (a) to component (b) is between 1 : 1.75 and 1 : 2.25.

3. A composition as claimed in claim 2 wherein the ratio by weight of component (a) to component (b) is about 1 : 2.

4. A composition as claimed in any one of the preceding claims wherein the ratio by weight of component (b) to component (c) is between 8 : 1 and 12 : 1.

5. A composition as claimed in claim 4 wherein the ratio by weight of component (b) to component (c) is about 10 : 1.

6. A composition as claimed in any one of the preceding claims having a pH of from 1.5 to 4.

7. A composition as claimed in claim 6 wherein the pH is from 2.0 to 2.9.

8. A composition as claimed in claim 7 wherein the pH is 2.5.

9. A composition as claimed in any one of the preceding claims including at least one binder.

10. A composition as claimed in claim 9 wherein the binder is an alkali metal silicate.

11. A composition as claimed in claim 10 wherein the binder is a mixture of sodium hexafluorosilicate and sodium metasilicate.

12. A composition as claimed in any one of claims 9 to 11 wherein the binder is present in an amount of up to 1% by weight, based on the weight of the composition.

13. A composition as claimed in any one of the preceding claims including a water-repellant additive.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. Time to catch Total flaming char length fire (secs) time (secs) (cm) NOMEX 920 (Registered Trade Mark) Fire Brigade Cloth Untreated 4 12 2 Treated - - 1 Polyester/Wool Overalls Untreated 3 28 3 Treated 3 14 10 By Donaghadee Carpets, N. Ireland: The material tested was Acrylan pile carpet on foam rubber back - test carried out in accordance with British Standard 4790:1972. Untreated Burning time 1.90 min. Smoking time 1.10 Radius of burnt pile 40 mm Radius of burnt foam 11 mm Treated Burning time 0.75 min. Smoking time 1.05 Radius of burnt pile 40 mm Radius of burnt foam NIL - no damage. In dermatitic tests, the solution of the present invention was found to be completely non-irritant to the skins of rabbits in accordance with the FDA Handbook test for primary skin irritation. WHAT I CLAIM IS:

1. A flame-proofing and fire retardant composition comprising an aqueous solution of: (a) ammonium hydrogen sulphate, (b) ammonium dihydrogen phosphate, and (c) diammonium hydrogen phosphate

2. A composition as claimed in claim 1 wherein the ratio by weight of component (a) to component (b) is between 1 : 1.75 and 1 : 2.25.

7. A composition as claimed in claim 6 wherein the pH is from 2.0 to 2.9.

8. A composition as claimed in claim 7 wherein the pH is 2.5.

14. A composition as claimed in claim 13 wherein the water-repellant additive is sodium

stearate.

15. A composition as claimed in claim 13 or claim 14 wherein the water-repellant additive is present in an amount of up to 0.5% by weight, based on the weight of the composition.

16. A composition as claimed in any one of the preceding claims including at least one additional ammonium salt.

17. A composition as claimed in claim 16 wherein the additional ammonium salt is ammonium sulphamate.

18. A composition as claimed in claim 16 wherein the additional ammonium salt is ammonium metaborate.

19. A composition as claimed in any one of claims 16 to 18 wherein the additional ammonium salt(s) is present in a total amount of up to 4% by weight, based on the weight of the composition.

20. A composition as claimed in any one of the preceding claims including a hypochlorite salt.

21. A composition as claimed in claim 20 wherein the hypochlorite salt is present in an amount of up to 0.01% by weight, based on the weight of the composition.

22. A composition as claimed in claim 20 or claim 21 wherein a chloride salt is additionally present.

23. A comPosition as claimed in claim 22 wherein the weight ratio of hypochlorite salt to chloride salt is between 1 : 8 and 1 : 20.

24. A composition as claimed in any one of the preceding claims including disodium hydrogen phosphate.

25. A composition as claimed in claim 1 substantially as hereinbefore described.

26. An anhydrous mixture which on dissolution in water yields a composition as claimed in any one of the preceding claims.

27. A synthetic material when treated with a composition as claimed in any one of claims 1 to 25.