WO2005026246A1

WO2005026246A1 - Fire retardant coating

Info

Publication number: WO2005026246A1
Application number: PCT/GB2004/003926
Authority: WO
Inventors: Keith Barkway Davies; Claire Barry
Original assignee: Isca Uk Limited
Priority date: 2003-09-16
Filing date: 2004-09-14
Publication date: 2005-03-24

Abstract

A fire retardant coating which includes an aqueous solution and/or dispersion of: a base metal synergist; a film former; and a plastisol grade polyvinyl chloride.

Description

Fire Retardant Coating

The present invention is concerned with a fire retardant coating suitable for use on fabrics. In particular, liquid surface coating compositions for making textiles fire retarding.

Textiles that are mainly used in the manufacture of upholstery, curtains and other soft furnishings typically require treatment in order to make them flame retarding. Typically, foamed liquids are applied via rolls with blades to control the thickness of the foamed material applied. The foaming is done by mechanically agitating the liquid and then pumping it onto a roll (Knife over air) or surface to be then transferred to the textile. From pre-rolled textile, the thin wet coating on the back of the textile is then passed through a high velocity hot air drying oven to completely remove the volatile content and when dry, finally the textile is rolled up. The types of coating used are generally water-based polymer in dispersion or solution containing active fire retarding chemicals. The subject of fire retarding chemicals is well known (see for example "The Chemistry and use of Fire retardants" by John W. Lyons published by John Wiley) .

Different groups of chemicals behave in different ways and have different effects on the environment. The United Nations Environment Programme, International Labour Organisation, World Health Organisation have published "International Programme on Chemical Safety, Environmental Health Criteria 192", Flame Retardants "A General Introduction", which describes in detail the various ways in which the chemistry of fire retarding is carried out. The basic physical action of flame retarding chemicals is by cooling, formation of a protective layer, by dilution and by chemical action. Chemical action is reaction in the gas phase, condensed phase and reaction in the solid phase. The approach in this technology is reaction in the gas phase .

Antimony oxides are not used as a flame retardants, but are used as a synergist with halogen compounds. Antimony oxides and appropriate halogen donating compounds (which may be available in several forms but are preferred in particulate form) are dispersed into a water phase in which a synthetic emulsion polymer derived from vinyl or acrylic chemistry, which may contain chlorine as part of the polymer or copolymer backbone base, is incorporated. Other additives including wetting agents, de-foaming agents, after glow depressants, thickeners, foaming agents, foam stabilisers and plasticisers (flexing) agents are also used.

Typical fire retarding compounds for textile backcoating may include the following:

Item % Description

Water 26. 4% Carrier phase

Antimony Trioxide 13, 2% Base metal synergist Di Aryl Bromine 25.0% Halogen donor

Acrylic or Vinyl ester emulsion in water 24.5% Film former Sodium salt of an acrylic resin 0.6% Wetting agent Bland of paraffin hydrocarbons 0 1% Bubble breaker

Di Alkyl Aryl Phosphate 4 5% Flexibliser

Inverse acrylic polymer 1, 0% Thickener

Sodium Alkyl Sulphate 2 0% Foaming agent Sodium Sulphosuccinamate 2 5% Foam stabiliser Ammonia 0.1% pH adjuster

All items are high speed dispersed using an impeller disk type of mixer (Cowles type) until a very fine dispersion is made of a Hegman grind reading gauge of 5.5 - 6.6:

Solid content 57%, pH 7.5 - 8.5 and Viscosity 1,500 to 4,000 centipoises Brookfield RVT spindle number six at 100 revolutions per minute at 20 degrees Celsius.

The composition is then typically foamed using methods known in the art and subsequently applied to the material to be coated.

However, there are a number of problems associated with typical fire retarding compositions. The basic problem with such compositions is their moderate resistance to water; this is due to the high surfactant content which is used for foaming combined with the water based polymers produced which contain hydrophilic groups. Therefore a coating is produced that has an affinity for water and can swell and even delaminate. Environmentally, bromine is continually being monitored by both authorities and commercial customers, and reduction or elimination in the use of fire retardant compositions is desirable.

High costs of Antimony and Bromine chemicals results in compounds which are high in cost and in turn processing costs can be high making low film weights particularly desirable .

Furthermore, the environmental issues relating to the use of bromine containing chemicals is resulting in the desire to substantially reduce their use in industry.

It is therefore an aim of the present invention to alleviate at least some of the disadvantages identified above.

It is a further aim of the present invention to provide a composition for use as a flame retardant.

Therefore according to a first aspect of the present invention there is provided a fire retardant coating which includes an aqueous solution and/or dispersion of: a base metal synergist; a film former; and a plastisol polyvinyl chloride.

Synergism is the phenomenon in which the combined action of two substances produces a greater effect than would be expected from the individual effects of each substance. Certain compounds of metals used as a synergistic co- additive, in combination with halogen compounds, facilitate the reduction in total flame retardant levels to achieve a desired level of flame retardancy.

Polyvinyl Chloride (PVC) is produced by various methods:

1 Mass or bulk polymerisation.

2 Solution polymerisation.

3 Emulsion polymerisation.

4 Suspension polymerisation.

The most important commercially is suspension, followed by emulsion and mass polymeristaion. Solution is important for a few speciality types. Mass or bulk polymerisation, or more accurately bulk, is produced in vast quantities; for example, one UK producer produces 45,000 ton per annum.

Emulsion polymerisation is dispersed in water and results in a stable or latex of very small polymer particles. Typical polymers will have particle sizes of 0.05 - 0.25 microns, and be stable emulsions in water. This latex can also be spray dried and produce dry polymer powder which has a particle size of about 30 - 50 microns which can then be blended with plasticizer. This form of PVC is known as plastisol or paste grades and although the same process of polymerisation is used, one form is in a stable liquid water based emulsion the other in powder form with much larger particle size.

Latterly suspension grades bare a superficial resemblance to emulsion in that the monomer is polymerised while dispersed droplets throughout an aqueous phase. The resultant polymer has much larger particle sizes then the emulsion polymerised grade.

The PVC of the present invention, is concerned with the emulsion polymerisation process which produces two different types of physical forms of 'PVC which may be defined as: a) Emulsion grade which is commonly called a latex grade, fine particle stable white milky liquid with about 50% of water being present. b) Emulsion grade which is commonly known as a paste grade, this is a white powder much coarser particle size and normally used with plasticizer and not water. Products made for this type of PVC are known as plasticized PVC. Un- Plasticized is known as uPVC as in window manufacture. The present invention is particularly concerned with emulsion grade PVC manufactured by the method identified in paragraph b) above.

Flame retarding coatings manufactured according to the present invention have a number of advantages over prior art flame retarding coatings, these include:.

Ease of manufacture Very good fire retarding even at relatively low additions

Good surface smoothness

Very good water soak resistance

Very good flexibility

Very good foaming ease Excellent drying speed

Furthermore, they can be manufactured substantially free of bromine containing compounds.

Poly Vinyl Chloride is a low cost polymer that is produced in very large quantities. Particularly preferred PVC according to the present invention is PVC grades used in plastisol manufacture. Such PVC polymers and their technologies are well described in "Plastisols and Organosols" 1972 by H. A. Sarvetnick. The use of P.V.C. in the manufacture of plastisols is done^* exclusively with plasticisers and not water. Plasticisers are described in literature "The Technology of Plasticizers" by J. K. Sears and J. R. Darby published by Willey Interscience 1982.

It is preferred that the aqueous content of the coating is about 5% to 80% by weight of the coating. A particularly preferred amount is 20% to 65%, such as 40% to 50% by weight of the coating. The aqueous content (water) may be separately added to the coating during manufacture, however, it is also envisaged that the components of the coating may include sufficient water such that the desired percentage is achieved substantially without addition of water as a separate component .

The fire retardant coating preferably has a pH which is substantially neutral or alkaline. It is particularly preferred that the coating has a pH above 8.0, such as above 8.5.

The base metal synergist may be oxides of zinc, tin and antimony, zinc borate, zinc hydroxyl stannate, zinc stannate, antimony pentoxide or antimony trioxide (which is particularly preferred) .

The base metal synergist is typically present in an amount

1% to 40% by dry weight of the coating. Preferably, 5% to 30%, such as about 10% to 12% by dry weight of the coating.

The film former may be of the type commonly known to a person skilled in the art, such as synthetic polymer dispersion in water which, when a wet layer is applied to a substrate and the water evaporates a film of polymer is deposited on the substrate which may be^v flexible or hard depending on the composition of the polymer. The film former may include a halogen containing film former, such as an acrylic or a vinyl type (which are preferably soft to handle and have low glass transition temperatures, such as less than ten degrees Celsius) . Further examples of suitable film formers include acrylonitrile based film formers.

The film former is typically present in an amount in the range 5% to 40% by dry weight of the coating. A preferred range is 8% to 30% by dry weight of the coating; further preferably 10% to 14% by dry weight of the coating.

The PVC may include plastisol grade or suspension grade. It is envisaged that if a coarse grade PVC is used, it may be milled to the desired grade prior to, or subsequent to blending the coating. However, the plastisol grade PVC may be passed through a sand or bead mill in water, prior to use. This is particularly advantageous as the resultant coating is an almost transparent coating which may be desirable for many applications. Prior art coatings which have good transparency typically use high amounts of bromine containing compounds, which are becoming undesirable due to both environmental issues and cost.

The PVC is typically present in an amount in the range 5 to 60% by dry weight of the coating. A preferred range is 5 to 50%, such as 8 to 40% by dry weight of the coating, more preferably 15 to 30%. Preferred PVC grades are homo or copolymers of Poly Vinyl Chloride and/or Poly Vinyl Acetate. The PVC s used are paste making emulsion polymers and have fine to very fine particle size of less then 1% retained on a 63 micron sieve as test method DIN 53195, ISO 1624. The K values may rage from 60 - 90 as test methods DIN 53276, ISO 1628-2. Typical chlorine contents are in the order of 50% to 60% of repeated mol unit. Advantageously, the PVC acts as a halogen donor.

Preferably, plastisol grades of PVC are low cost and very water resistant (no hydrophilic groups) and therefore give major improvements to typical textile fire retarding compounds. The high Chlorine content of these polymers donates halogen to the synergistic action with Antimony and is more cost effective than Bromine and imparts inherent water resistance due to the hydrophobic nature of the polymer .

It is very desirable that no stiffening takes place when the fabric when coated and dried. Normal methods of giving the film of textile fire retarding coating the flexibility required are to add plasticisers by rapid stirring or pre emulsification. It is therefore envisaged that a plasticiser may be added to the fire retardant coating. The plasticiser may be based on phosphoric acid esters known as phosphates (these phosphates are oily liquids and impart better handle to the fabric when the coating is applied and dried) .

Also the phosphates significantly improve the after glow problem which occurs when the flame is suppressed and the fabric continues to glow. These plasticisers react very rapidly with P.V.C. dispersions in water, the plasticiser preferentially wets the PVC and displaces the water from the PVC surface and results in a coagulate. The P.V.C. plasticiser reaction results in a type of flocculation effect. If P.V.C. is used then plasticisers of a large number of generic chemical groups will coagulate the dispersion, producing an undesirable or unusable coating.

A way to overcome this flocculation effect and still give the coating flexibility is to use soft polymers as the flexibility agents. Alternatively, a plasticiser that does not react and cause flocculation could be used, this may include a chlorinated paraffin (which is particularly preferred) . Chlorinated paraffins are substantially cheaper than soft polymers. The amount required to give the desired flexibility in the flame retardant coating is substantially reduced when compared to using soft polymers. In addition, as the chlorinated paraffin contains substantial amounts of chlorine it is beneficial in suppressing flames.

Preferably, the flame retardant coating includes an after glow suppressant. The after glow suppressant may be a borate or a phosphate, although borates are preferred. Borates are preferred as certain phosphates may have adverse effects when blended with PVC (for example, they may coagulate) . A particularly preferred borate is zinc borate .

The after glow suppressant is preferably in particulate form and the particle size of below 20 microns, typically 4 to 8 microns.

The after glow suppressant is typically present in an amount in the range 2% to 25% by dry weight of the coating. A preferred amount is from 3% to 15%, such as about 3.5% to 7.5% by dry weight of the coating.

Preferably, the fire retardant coating further includes a thickening agent. The thickening agent may be of the type commonly known by the person skilled in the art. Typical thickening agents include starches, xanthane gums, natural gums, inverse types including dispersions in plasticiser and or kerosene, cellulose ether derivatives, poly vinyl alcohol, polyurethane, poly acrylic acid derivatives and poly acrylate types water swellable types. However, a particularly preferred thickening agent is an inverse acrylic polymer.

The thickening agent is preferably present in an amount in the range 0.1% to 7% by dry weight of the coating. Further preferably in an amount 0.2% to 5% by dry weight, such as about 0.25% to 2% by dry weight of the coating.

It is envisaged that the coating may be applied to the substrate (such as fabric, textile or the like) to be treated, by a foam application system or by screen- printing. Both methods of application are known in the art of application of fire retardants.

If the coating is to be applied using a foaming system, it is desirable that the coating further includes a foaming agent and/or a foam stabiliser.

The foaming agent may be Sodium alkyl sulphates, Alcohol ethoxylates, Alkanolamides, Alkylaryl sulphonates, alkyl phenol ethoxylates, amine ethoxylates, amine oxides, also amphoterics i.e benzyl quats, block co-polymers; fatty acid ethoxylates, glycerol esters, higher alcohol ethoxylates, lower alcohol ethoxylates, sulphosuccinates, sulphosuccinate half ester, and/or phosphate esters. However, sodium alkyl sulphate is preferred.

Advantageously, the foam stabiliser substantially prevents the foam collapsing. Suitable foam stabilisers include sodium sulphosuccinamate, ammonium stearate, sulphoalkanolamides and/or alkanolamide ethoxylates. However sodium sulphosuccinamate is preferred.

The foaming agent is typically present in the coating in an amount 0.0% to 5% by dry weight of the coating. A preferred amount is in the range 0.5% to 4% by dry weight of the coating, such as about 0.6%.

The foam stabiliser is typically present in an amount of about 0.0% to 5.0% by dry weight of the coating; a preferred amount is in the range 0.5% to 4% by dry weight, for example about 0.2%.

The coating may further include a dispersing agent. Suitable dispersing agents include sodium salts of acrylic acid, sodium salts of fatty acids, alcohol ethoxylates, alkyl aryl sulphonates, polyglycol fatty acid esters and lower alcohol ethoxylates, however, a sodium salt of an acrylic resin is particularly preferred. The dispersing agent is typically present in an amount in the range 0% to 2.0% by dry weight of the coating.

Desirably, the coating may further include a defoamer; the defoamer advantageously assists in the removal of bubbles during the manufacture of the coating. Suitable defoamers include polymethylsiloxanes, polyphenylsiloxane, (fluids and polymers) , Fatty acid esters of high alcohols, hydrocarbon liquids of various molecular weight including paraffinic and naphthanic types. However, a preferred defoamer includes a blend of paraffin hydrocarbons. The defoamer is typically present in an amount in the range 0% to 1% by dry weight of the coating, preferably 0.05% to 0.5%, such as about 0.1%.

It is envisaged that the fire retardant coating may include a further halogenated compound, for example a bromine or chlorine compound.

It is preferred that the further halogenated compound is a brominated flame retardant such as hexabromocyclododecane, tetrabromobisphenol A, dibromostyrene, tetrabromophthalic anhydride, brominated diphenyl oxide, tribromophenol, or a derivative of any of the aforementioned brominated flame retardants. A particularly preferred flame retardant is the diaryl bromine, deca bromo di phenyl oxide known as deca or a commercial grade known as Great Lakes DE83R. Preferably, the halogen compound has a bromine content from 36% to 90%.

It is particularly preferred that when the base metal synergist includes antimony and the further halogen compound contains bromine and/or Chlorine, the molar ratio of antimony to halogen is 1:1-5, preferably but not limited to 1:2-3.5.

The further halogenated compound is desirably present in an amount in the range 1% to 60% by dry weight of the coating. Preferably, the halogen compound is present in an amount in the range 5% to 40%, such as 10% to 30% by dry weight of the coating.

Therefore, according to a further aspect of the present invention, there is provided a fire retardant coating which includes an aqueous solution and/or dispersion of: a base metal synergist; a halogenated compound; a film former; and a plastisol grade polyvinyl chloride.

The base metal synergist, halogenated compound, film former and a polyvinyl chloride are substantially as described hereinbefore with reference to the first aspect of the present invention.

According to yet a further aspect of the present invention, there is provided a method of manufacturing a flame retardant coating, which method includes: a) providing a blend of a base metal synergist, a film former and a polyvinyl chloride; b) agitating the blend so as to form a dispersion. The flame retardant coating is substantially as described hereinbefore with reference to the first aspect of the present invention.

The agitation in step b) is typically by mechanical means, for example a high-speed mixer. However milling equipment may also be used. It is envisaged that many different mixing techniques known in the field of blending may be used according to this aspect of the present invention so as to achieve the desired blend.

It is particularly preferred that the plastisol grade PVC may be passed through a sand or bead mill in water. This is advantageous because the resultant blend has extremely good transparency properties.

Preferably, the blend in step a) is achieved by blending the components typically in the following order:

Water Film Former (part of addition)

Base metal synergist

Brominated flame retardant (when present) polyvinyl chloride

An after glow suppressant agent (when present)

However, it is envisaged that the blend ^vmay be achieved by blending the components in a different order.

It should be noted that if one or more of the components includes water in the desired amount, additional water does not need to be included.

According to a particularly preferred method according to the present invention, the components are added in the following order, when they are present in the flame retardant coating:

Water

Film Former (part of addition)

Dispersion agent Defoamer

Thickener

PH adjuster.

Base metal synergist

Brominated flame retardant Halogen donor Plastisol grade polyvinyl chloride

After glow suppressant

A film former

Thickener

Foaming agent Foam stabiliser

PH adjuster.

It is particularly preferred that the method is carried out under substantially neutral or alkaline conditions. Preferably the pH is above 8.0 (further preferably above 8.5). It is envisaged that a pH adjuster is added to the blend during the manufacture process to maintain the pH at the desired level.

The present invention will now be described by way of example only, with reference to the following examples.

Example 1

The following ingredients were combined and high speed dispersed until a very fine dispersion is achieved.

All items are high speed dispersed until a very fine dispersion is made a Hegman reading of 5.5 - 6. Solid content 57% . pH 7.5 - 8.5 Viscosity 1,500 to 4,000 centipoises cPs or mili pascal seconds m(Pa) sec Brookfield RVT spindle number 5 at 100 revolutions per minute at 20°C.

The application of the above composition is then done as follows. The composition is pumped through a mechanical foamer and set to continually foam until a foam density of 100 to 700 grams per litre is obtained. This resulting foam is pumped onto a roller approximately 1.4metres wide and then applied by a ^Doctor blade' to the back of the fabric as a very thin film. The foam allows the coating not to penetrate through to the face of the fabric and discolour any face pattern. The foam, when running through the Doctor blade, readily collapses and is completely a non-cell, bubble free coating. Normal film weights of such compounds are in the order of 20 to 45 percent dry addition on the weight of the fabric. As a general rule the more mass of a fabric the more coating should be applied. The resulting film is then exposed to a drying oven with high velocity air passing through when all the water is removed and the film, on exit from the oven, is essentially free from volatiles.

The resulting coated fabric is then tested to the UK contract upholstery fabric tests - BS7176/BS5852 (BS EN 1021) . Part 0 cigarette test, part 1 is a match test for fire retarding performance, Flame source 0/1/5/7. The treated fabric must also be tested to BS5651 for resistance to water soak proving that the coating will be still fire retarding after exposure to water.

Example 2

All items are high speed dispersed until a very fine dispersion is made a Hegman reading of 5.5 - 6. Solid content 57% .pH 7.5 - 8.5 Viscosity 1,500 to 4,000 centipoises cPs or mili pascal seconds m(Pa) sec Brookfield 'RVT spindle number 5 at 100 revolutions per minute at 20°C.

The application of the above composition to a material is carried out substantially as described hereinbefore with reference to Example 1.

Claims

1. A fire retardant coating which includes an aqueous solution and/or dispersion of: a base metal synergist; a film former; and a plastisol grade polyvinyl chloride.

2. A coating according to Claim 1, wherein the aqueous content of the coating is about 5% to 80% by weight of the coating.

3. A coating according to claim 2, wherein the aqueous content of the coating is 20% to 65% by weight of the coating.

4. A coating according to claim 3, wherein the aqueous content of the coating is 40% to 50% by weight of the coating.

5. A coating according to any preceding claim, which has a pH which is substantially neutral or alkaline.

6. A coating according to claim 5, which has a pH above 8.0.

7. A coating according to claim 6, which has a pH above 8.5.

8. A coating according to any preceding claim, wherein the base metal synergist may be oxides of zinc, tin and antimony, zinc borate, zinc hydroxyl stannate, zinc stannate.

9. A coating according to claim 8, wherein the base metal synergist is antimony pentoxide or antimony trioxide.

10. A coating according to any preceding claim, wherein the base metal synergist is present in an amount 1% to 40% by dry weight of the coating.

11. A coating according to claim 10, wherein the base metal synergist is present in an amount 5% to 30% by dry weight of the coating.

12. A coating according to claim 11, wherein the base metal synergist is present in an amount 10% to 12% by dry weight of the coating.

13. A coating according to any preceding claim, wherein when to the base metal synergist includes antimony, the molar ratio of antimony to halogen is 1:1-5.

14. A coating according to claim 13, wherein the molar ratio of antimony to halogen is 1:2-3-5.

15. A coating according to any preceding claim, wherein the film former includes a halogen containing film former (such as an acrylic or vinyl type ) or an acrylonitrile based film former.

16. A coating according to any preceding claim, wherein the film former is present in an amount in the range 5% to 40% by dry weight of the coating.

17. A coating according to claim 16, wherein the film former is present in an amount in the range 8 to 30% dry by weight of the coating.

18. A coating according to claim 17, wherein the film former is present in an amount in the range 10 to 14% by dry weight of the coating.

19. A coating according to any preceding claim, wherein the PVC is present in an amount in the range 5 to 60% by dry weight of the coating.

20. A coating according to claim 19, wherein the PVC is present in the range 5 to 50% by dry weight of the coating .

21. A coating according to claim 20, wherein the PVC is present in the range 8 to 40% by dry weight of the coating.

22. A coating according to claim 21, wherein the PVC is present in the range 15 to 30% by dry weight of the coating.

23. A coating according to any preceding claim, wherein the PVC is homo or copolymers of poly vinyl chloride and/or poly vinyl acetate.

24. A coating according to any preceding claim, which includes a plasticiser.

25. A coating according to claim 24, wherein the plasticiser include a chlorinated paraffin.

26. A coating according to any preceding claim which includes an after glow suppressant.

27. A coating according to claim 26, wherein the after glow suppressant is a borate or phosphate.

28. A coating according to claim 26 or 27, wherein the after glow suppressant has a particle size of below 20 microns.

29. A coating according to claim 26 to 28, wherein the after glow suppressant is present in an amount in the range 2% to 25% by dry weight of the coating.

30. A coating according to claim 29, wherein the after glow suppressant is present in an amount in the range 3% to 15% by dry weight of the coating.

31. A coating according to any preceding claim, wherein the coating includes a thickening agent .

32. A coating according to claim 31, wherein the thickening agent includes, an inverse acrylic polymer starches, xanthane gums, natural gums, inverse types including dispersions in plasticizer and or kerosene, cellulose ether derivatives, poly vinyl alcohol, polyurethane, poly acrylic acid derivatives and/or poly acrylate type water soluable type agents.

33. A coating according to claim 31 or 32, wherein the thickening agent is present in the range 0.1% to 7% by dry weight of the coating.

34. A coating according to claim 33, wherein the thickening agent is present in the range 0.2% to 5% by dry weight of the coating.

35. A coating according to any preceding claim, which includes a foaming agent and/or a foam stabiliser.

36. A coating according to claim 35, wherein the foaming agent includes Sodium alkyl sulphates, Alcohol ethoxylates, Alkanolamides, Alkylaryl sulphonates, alkyl phenol ethoxylates, amine ethoxylates, amine oxides, also amphoterics i.e benzyl quats, block co- polymers; fatty acid ethoxylates, glycerol esters, higher alcohol ethoxylates, lower alcohol ethoxylates, sulphosuccinates, sulphosuccinate half ester, and/or phosphate esters.

37. A coating according to claim 35 or 36, wherein the foam stabiliser includes sodium sulphosuccinamate, ammonium stearate, sulphoalkanolamides and/or alkanolamide ethoxylates.

38. A coating according to any of claims 35 to 37, wherein the foaming agent is present in an amount in the range 0.0% to 5% by dry weight of the coating.

39. A coating according to claim 38, wherein the foaming agent is present in an amount in the range 0.5 to 4% by dry weight of the coating.

40. A coating according to any of claims 35 to 39, wherein the foam stabiliser is present in an amount 0.0% to 5% by dry weight of the coating.

41. A coating according to claim 40, wherein foam stabiliser is present in an amount 0.5% to 4% by dry weight of the coating.

42. A coating according to any preceding claim, which includes a dispersing agent.

43. A coating according to claim 42, wherein the dispensing agent is a sodium salts of acrylic acid, sodium salts of fatty acids, alcohol ethoxylates, alkyl aryl sulphonates, polyglycol fatty acid esters and lower alcohol ethoxylates, or a sodium salt of an acrylic resin.

44. A coating according to claims 42 or 43, wherein the dispersing agent is present in the range 0% to 2.0% by dry weight of the coating.

45. A coating according to any preceding claim, which further includes a defoamer.

46. A coating according to claim 45, wherein the defoamer includes polymethylsiloxanes, polyphenylsiloxane, (fluids and polymers) , Fatty acid esters of high alcohols, hydrocarbon liquids of various molecular weight including paraffinic and naphthanic types, or a blend of paraffin hydrocarbons.

47. A coating according to claim 45 or 46, wherein the defoamer is present in an amount in the range 0.0% to 1% by dry weight of the coating.

48. A coating according to any preceding claim, which further includes a further halogena'ted compound.

49. A coating according to claim 48, wherein the further halogenated compound is hexabromocyclododecane, tetrabromobisphenol A, dibromostyrene, tetrabromophthalic anhydride, brominated diphenyl oxide, tribromophenol, or a derivative of any of the aforementioned brominated flame retardants, diaryl bromine, deca bromo or diphenyl oxide.

50. A coating according to claim 48 or 49, wherein the further halogenated compound is present in the range 1% to 60% by dry weight of the coating.

51. A coating according to claim 50, wherein the further halogenated compound is present in an amount in the range 5% to 40% by dry weight of the coating.

52. A method of manufacturing a flame retardant coating, which method includes: a) providing a blend of a base metal synergist, a film former and a plastisol grade polyvinyl chloride; b) agitating the blend so as to form a dispersion.

53. A method according to claim 52, wherein blend is achieved by mixing the following components in the order water, film former, base metal synergist, PVC.

54. A method according to claim 52 or 53, wherein the blending is carried out under substantially neutral or alkaline conditions.

55. A method according to claim 54, wherein a pH adjuster is added (one or more times) to the blend during mixing so as to maintain the pH at the desired level.

56. A method according to any of claims 54 to 55, wherein the plastisol grade PVC is milled prior to, or subsequent to, blending the coating.

57. A method according to any of claims 52 to 56, wherein the plastisol grade PVC is passed through a sand or bead mill in water, prior to use.