Fire protection & mould retardant coating

Abstract

A water-based, intumescent coating for preventing mould or mildew comprises 19.00-23.00 pbw water, 8.75-10.60 pbw blowing agent, 8.75-10.60 pbw carbon donor, 0.45-0.55 pbw dispersant, 0.45-0.55 pbw de

Description

This invention relates to a water-based intumescent coating and coating system which is 5 suitable for eradicating and preventing the growth of mould. BACKGROUND TO THE INVENTION An intumescent coating is a fire-retardant coating which expands when exposed to high temperatures. These coatings are commonly used in buildings and structures to provide 10 passive fire protection by slowing down the spread of fire and protecting the underlying LO material from damage. CXI Intumescent coatings prevent the spreading of fires by forming a layer of foam through "1” chemical reactions when exposed to high temperatures. This is known as a ‘char’ which 1 provides insulation and reduces the surface temperature of the substrate of which it has been 15 applied to. Therefore, it slows down the rate of heat transfer and helps prevent the substrate from reaching its ignition point. The main components of an intumescent coating are acid donors, carbon donors and a blowing agent. An acid donor is a chemical that decomposes under high temperatures to release an acid. For 20 example, ammonium polyphosphate releases phosphoric acid. A carbon donor produces the char, which provides the insulating foam that protects the substrate. Carbon sources are typically polyols or sugars such as pentaerythritol or sorbitol. A blowing agent decomposes under high temperatures to produce a gas which helps expand char to create a thicker, foam-like layer. Typically blowing agents are nitrogen-rich compounds such as melamine and its derivatives. M. Jimenez et. al. (2006, Surf. Coat. Technol.) describes the mechanism of intumescent 5 coatings as follows: firstly, the acid donor decomposes under high temperatures to yield an acid, which catalyses the dehydration and crosslinking of the carbon donor to yield the carbon char. Finally, the blowing agent releases a gaseous product which promotes the swelling of the char to form a thick insulating layer of foam. Dry-film fungicidal biocides are a type of biocide that specifically protect the dry coated surface 10 from the growth and reproduction of microorganisms such as fungi, moulds and mildew. Commonly used fungicidal biocides in the coatings industry are 3-iodoprop-2-yn-1-yl butyl LO carbamate and isothiazolinones such as 2-octyl-2H-isothiazol-3-one. These biocides work CXI through the controlled release of the active ingredients into the surrounding environment over time. This minimises or prevents any structural damage to the substrate which is typically 1— 15 caused by moulds and mildews. 1— Known intumescent containing fire protection coatings typically fail to meet the criteria imposed by various Governmental bodies for the reason that the coating remains in place to prevent the passage of fire and smoke for a minimum period of 30 minutes. Typical of such requirements are those set by the European SPI test. Such coatings are applied in domestic 20 and commercial properties which are vulnerable to mould, a public health concern. Coatings in accordance with this invention have been found to significantly exceed this minimum time period to prevent the passage of fire and smoke and eradicate mould growth in domestic and commercial properties. STATEMENTS OF THE INVENTION In one aspect, the invention provides a water-based intumescent coating suitable for eradicating and / or preventing the growth of mould / mildew, whose composition comprises by weight: 19.00 to 23.00 parts water, between 8.75 to 10.60 parts blowing agent, between 8.75 5 and 10.60 parts carbon donor, between 0.45 and 0.55 parts dispersant, between 0.42 and 0.55 parts defoamer, between 0.18 and 0.22 parts in-can biocide, between 0.75 and 1.10 parts propanediol, between 23.00 and 27.00 parts acid donor, between 5.20 and 6.60 parts pigment, between 0.27 and 0.33 parts of a rheological additive, between 24.00 and 29.00 parts aqueous copolymer dispersion of vinyl acetate-vinyl neo decanoate and between 0.80 and 1.20 parts 10 of a dry-film preservative that contains fungicidal additives which target mould. A preferred blowing agent is melamine, LO A preferred carbon donor is a polyol such as monopentaerythritol, CXI A preferred acid donor is ammonium polyphosphate, 1— A preferred rheological additive is hydroxy ethyl cellulose, 1— 15 A preferred fungicidal additive of the dry film preservative is 2-octyl-2H-isothiazol-3-one. In another aspect, the invention provides a multi-layered coating system which comprises three different coating layers suitable for providing fire protection and an effective barrier to fungi or mould growth, wherein one of the layers comprises an intumescent water-based coating with a composition as described above. 20 Preferably, one of the additional coatings is a primer coating. Preferably, the other additional coating is a topcoat for an external surface. DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intumescent coating composition suitable for preventing the growth of mould and mildew. Specifically, the coating forms a part of a coating system, which in combination with additional layers of coatings prevents the growth of mould as well 5 as suffocating any existing forms of fungi, mould or mildew already present on the surface. The invention will now be described with reference to the following examples of coatings in accordance with the invention. Example 1 In this example, the composition of the coating was as follows: 20.50 parts water, 9.50 parts 10 melamine, 9.20 parts Monopentaerythritol, 25.00 parts ammonium polyphosphate, 0.75 parts propanediol, 0.42 parts defoamer, 0.19 parts in-can biocide, 0.50 parts dispersant, 5.20 parts LO pigment, 0.28 parts hydroxy ethyl cellulose, 26.00 parts vinyl acetate-vinyl neo decanoate copolymer dispersion and 1.00 parts dry-film preservative which contains 2-octyl-2H-isothiazol-3-one as the active ingredient. 1— C\J 15 In use, this coating was found to provide effective protection against the growth of mould for periods well in excess of 30 minutes. Example 2 In this second example, the composition of the coating is as follows: 21.00 parts water, 9.20 parts melamine, 9.00 parts monopentaerythritol, 24.50 parts ammonium polyphosphate, 0.80 20 propanediol, 0.47 parts defoamer, 0.19 parts in-can biocide, 0.45 parts dispersant, 5.56 parts pigment, 0.27 parts hydroxy ethyl cellulose, 25.30 parts vinyl-acetate-vinyl neo decanoate copolymer dispersion and 1.18 parts dry-film preservative which contains 2-octyl-2H-isothiazol-3-one as the active ingredient. Again, in use, this coating was found to provide effective protection against the growth of 25 mould for periods well in excess of 30 minutes. Example 3 In a third example, the composition of the coating comprised 21.5 parts water, 9 parts guanidine, 9.30 parts Tri pentaerythritol, 0.45 parts dispersant, 0.46 parts defoamer, 0.18 parts in-can biocide, 1.00 parts propanediol, 24.75 parts Tri ammonium phosphate, 5.69 parts 5 pigment, 0.31 parts carboxy methyl cellulose, 26.10 parts vinyl acetate-vinyl neo decanoate copolymer dispersion and 0.83 parts of a dry-film preservative that contains diodomethyl-p-tolyl sulfone as the active ingredient. Example 4 In a third example the composition of the coating comprised 19.56 parts water, 9.92 parts 10 dicyandiamide, 9.92 parts polyvinyl alcohol, 0.52 parts dispersant, 0.51 parts defoamer, 0.20 parts in-can biocide, 1.02 parts propanediol, 26.69 parts para-toluene sulphonic acid, 6.32 LO parts pigment, 0.28 parts ethyl hydroxy ethyl cellulose, 28.10 parts vinyl acetate-vinyl neo CM decanoate copolymer dispersion and 0.98 parts of a dry-film preservative that contains 3-lodo-1— 2-propynyl butyl carbamate as the active ingredient. ^^15 Alternative blowing agents which may be used in addition to those referred to identified in the Examples include melamine derivatives, melamine sales, guanidine, urea, dicyandiamide and azodicarbonamide. Alternative carbon donors which may be used include starch, Di pentaerythritol, Tri pentaerythritol, chlorinated paraffins and polyvinyl alcohol. 20 Alternative acid donors which may be used include para-toluene sulphonic acid, ammonium sulphate, sodium sulphate, potassium sulphate, monoammonium phosphate, diammonium phosphate and Tri ammonium phosphate. Alternative dry-film preservatives which may be used include dichlorooctylisothiazolinone, diodomethyl-p-tolyl sulfone or 3-lodo-2-propynyl butylcarbamate. Alternative rheology modifiers which may be used include hydroxy propyl methyl cellulose, methyl cellulose, carboxy methyl cellulose, methyl hydroxy ethyl cellulose and ethyl hydroxy ethyl cellulose. In all cases, the method of production comprised sequentially charging the specified quantities 5 of water, blowing agent, carbon donor, dispersant, defoamer, biocide, propanediol and acid donor, into a suitable vessel and mixing until all the contents are homogenous. Suitable means of mixing include, high-speed dispersers and emulsifiers. Once homogenous, the vessel was charged with the specified quantity of pigment and then mixed until the contents were homogenous. Periodically, the vessel was scraped down to 10 CXI prevent a build-up of paint around the periphery of the vessel. This step was repeated for the addition of each of the following ingredients: rheological additive, copolymer dispersion and dry-film preservative. After all components of the coating had been charged, the coating was mixed for around 15 minutes, after which, the vessel was scraped down again. CXI 15 The finished coating was then filtered as required. The coating produced was found to provide protection against fire for a period in excess of 2 hours, as well as eradicate pre-existing mould and prevent the further growth of new colonies of mould. In use, the exemplified intumescent water-based coatings are, applied between two additional 20 coatings to create a coating system that provides an effective barrier to fungi or mould growth. The additional coatings comprise a primer coating and a topcoat for an external surface. The foregoing coating system prevents the growth of mould across multiple layers and eliminates any fungal spores already present on the substrate, while also providing effective fire protection to the substrate. Suitable means of application may include a brush or roller. It will be appreciated that the foregoing is merely exemplary of coatings in accordance with the invention and that modifications can readily be made without departing from the true scope of the invention as set out in the appended claims. LO CXI i— i— CM

Claims

1. A water-based intumescent coating suitable for eradicating and / or preventing thegrowth of mould / mildew, whose composition comprises by weight: 19.00 to 23.00 partswater, between 8.75 to 10.60 parts blowing agent, between 8.75 and 10.60 parts carbondonor, between 0.45 and 0.55 parts dispersant, between 0.42 and 0.55 parts defoamer,between 0.18 and 0.22 parts of an in-can biocide, between 0.75 and 1.10 partspropanediol, between 23.00 and 27.00 parts acid donor, between 5.20 and 6.60 partspigment, between 0.27 and 0.33 parts of a rheological additive, between 24.00 and1029.00 parts aqueous copolymer dispersion of vinyl acetate-vinyl neodecanoate andbetween 0.80 and 1.20 parts of a dry-film preservative that contains fungicidal additiveswhich target mould.CXI2.A coatingasclaimed in Claim 1, wherein the blowing agent is melamine.3.A coatingasclaimed in Claim 1 or claim 2, wherein the carbon donor is a polyol.154.A coatingasclaimed in claim 3 wherein the carbon donor is monopentaerythritol.CXI5.A coating composition as claimed in any one of the preceding claims wherein the aciddonor is ammonium polyphosphate.6.A coating composition as claimed in any one of the preceding claims wherein therheological additive is hydroxy ethyl cellulose.207.A coating composition as claimed in any one of the preceding claims wherein thefungicidal additive of the dry-film preservative is 2-octyl-2H-isothiazol-3-one.8.A multi-layered coating system which comprises three different coating layers suitablefor providing fire protection and an effective barrier to fungi or mould growth, whereinone of the layers comprises an intumescent water-based coating with a composition as25claimed in any of Claims 1 to 7.9.A multi-layered coating system as claimed in Claim 8, wherein one of the additionalcoatings is a primer coating.

10. A multi-layered coating system as claimed in any one of Claims 8 to 9, wherein the other additional coating is a topcoat for an external surface.LO CXI i— i—CM