GB2169278A - Fire-protective composition - Google Patents

Abstract

A composition for forming a fire-protective coating, layer or impregnation when applied to a substrate comprises a mixture of charcoal, silica sand, bentonite, zinc oxide, fireclay, calcium carbonate, refractory concrete, monobasic sodium phosphate, ammonium sulphate, borax, linseed oil and white (lead-free) gasoline. The composition may be liquid or semi-liquid and should be applied to the substrate and allowed to dry thoroughly.

Description

SPECIFICATION Protective composition for application to a substrate This invention is concerned with a protective composition for application to a substrate.

The compositions of the invention are capable of forming a protective coating, layer or impregnation when applied to a substrate and allowed to dry.

Compositions have been widely developed for separately imparting to various materials a combination of protective properties which would advantageously be provided in a single maximum protection coating product, otherwise known as MRMP. Such separate compositions are used on ships, sleepers and posts in contact with the ground, for example treatment with coal creosote or beech creosote, in order to render them bactericidal against the pests and organisms which generally adhere to or attack the wood and cause it to deteriorate, such as fresh-water crustaceans and wood boring pests.Various materials have also been treated with fire retarding agents, but we know of none with fire inhibiting characteristics, much less when applied to surfaces such as the hulls of vessels, which presents a real threat to be combated, in view of the climatic, physical, chemical and biological attack to which they are exposed. Such materials are exposed to a wide variety of risks and damage if they are not provided with suitable protection, even when a combination of partial protection measures is taken which does not always cover all or most of such dangers such as corrosion, deterioration of materials, inflammability and so forth.

This is why MRMP constitutes a means of satisfying a number of requirements, in particular productivity, economy and safety.

The main function of the protection composition of this invention is that of a fire inhibiting agent, although in general bactericidal, anti-corrosive, impermeability and thermo-refractory properties may also be imparted. While we are not to be limited by any particular theory, we believe this is obtained by two fundamental mechanisms: 1) by virtue of its constituents the applied coating of MRMP on a surface of a material forms a real refractory barrier which prevents the attainment of high temperatures compatible with those of flames, which fluctuate around 2000"C, whereas those reached by the product (MRMP coating) fluctuate around 60"C, so that temperature is obviously far below that prevailing in the flame.

2) ingress of oxygen into the MRMP coating is restricted as a result of the formation of crystals in the intermolecular spaces of the MRMP coating and the formation of a polymer film on contact with the heat, isolating it from the entry of the air required for adequate combustion.

According to this invention there is provided a protection composition comprising a mixture containing charcoal, silica sand, bentonite, zinc oxide, fireclay, calcium carbonate, refractory concrete, monobasic sodium phosphate, ammonium sulphate, borax, linseed oil and white (i.e. lead-free) gasoline. The weight ratio of components in a preferred composition of the invention can be determined on the basis of the following preferred composition: No. Constituent Parts by Preferred weight Quantity 1 Charcoal 400 to 600 500 grs.

2 Silica sand 400 to 600 500 grs.

3 Bentonite 200 to 300 250 grs.

4 Zinc oxide 400 to 600 500 grs 5 Borax 40 to 60 50 grs.

6 Fireclay 150 to 250 200 grs.

7 Calcium carbonate 120 to 180 150 grs.

8 Refractory concrete 200 to 270 235 grs.

9 Ammonium sulphate 120 to 180 150 grs.

10 Monobasic phosphate of sodium 150 to 250 200 grs.

11 Linseed oil 600 to 900 750 mls.

12 Lead-free gasoline 600 to 900 750 mls.

The charcoal, silica sand and zinc oxide are generally present in approximately equal amounts by weight and, based on the total weight of solid components in the mixture, the content of each of bentonite, fireclay, calcium carbonate, refractory concrete,monobasic sodium phosphate and ammonium sulphate is conveniently about 5 to 10%, that of borax about 1 to 2% and that of both the linseed oil and lead-free gasoline about 15 to 25%.

The compositions of the invention may, for example be made by the following preferred method.

Stage 1 The dry constituents are mixed from 1"C to 10 C, both the charcoal and the silica sand being ground down to the best size for the application concerned, according to whether the product is to be used as a "paint" or as a semi-liquid plaster-like material.

Stage 2 The linseed oil (750 mls) is added to the above dry mixture in such a way that all the constituents are integrated into the mixture and that the latter becomes as homogenous as possible.

Stage 3 The 750 mls of white gasoline are added to the product of the above mixing process and incorporated therein.

Final result, In the case of a paint a liquid of thick consistency is obtained, the colour being originally grey and the density being 40 Baume.

In the case of the semi-liquid plaster like material the colour undergoes no variation, although its consistency is thicker.

Application.

The paint suffices for 10-12 m2 of surface with a thickness of 15,u and the "plaster" for 3-4 m2 with a thickness of 1 cm.

The application of the product (MRMP) will increase the weight of the objects concerned, the percentage of weight increase being greater when the product is fresh than after it has dried. As an example, a piece of three-ply wood measuring 15 x 15 x 3 cm and with an initial weight of 65 grs increased in weight to 80 grs. (i.e. by 23%) when the MRMP coating was still damp, the weight being 75 grs. (15.3% above the initial weight) after it had dried.

The drying time will depend on the characteristics of the object to which the MRMP is to be applied, the average time being 72 hours; this can be reduced by adding to the finished product, a few moments before its application, 250 mls of thinner per litre of product, the two preparations being thoroughly incorporated in each other. This reduces the drying time by about 50%.

The product can be aplied in any convenient manner, for example, as a paint with a hair brush, or with a compressor gun (by spraying), or as a plaster.

The properties of the product will only fully develop after thorough drying after application.

The MRMP of the invention can be applied to practically any surface, its application frequently depending on the creative imagination of the user, it being borne in mind that the MRMP alters the physical appearance and in many cases the aesthetic character of the articles to which it is applied.

Some of the materials to which it can be applied are mentioned below: --Any type of wood or agglomerate.

--Foam rubber.

--Glass.

--Any type of plastic and containers of the same material.

--Polythyrenes, polyurethane false ceilings.

--Fibre glass.

--Clay, bricks, cement.

--Metals of any type (including those used for the interior lining of car bodies).

Incidental advantages which may from time to time accrue from the application of the composition may include: --Increase in the strength of certain materials, as in the case of wood, of which it increases the resist ance to rupturing by up to 30%.

--Reduction of corrodibility.

--Prevention of deterioration of certain materials exposed to aggression from certain organisms such as bacteria and acts as a bactericide.

The composition being made from readily available raw materials, is inexpensive to produce.

Some preferred embodiments of the invention will now be described for the purpose of illustration only in the following Examples.

Example 1: A coating of MRMP formulated according to the recipe given above of about 3 ,a in thickness is applied as a paint with a hair brush to one side of a piece of three-ply wood measuring 15 cms x 15 cms x 3 mm. It is left to dry for 72 hours at ambient temperature, after which it is exposed to a direct flame of 2000"C, no flame occurring on the MRMP coating even after 7 minutes.

Example 2: A coating of MRMP formulated according to the recipe given above of about 3 > is applied as a paint to the entire surface of a piece of three-ply wood measuring 20 cms x 20 cms x 3mm, after which it is left to dry for 72 hours and then placed in an electric furnace with a temperature of 3000"C for 5 hours, no flame occurring and the wood undergoing no carbonization.

Claims (10)

1. A protection composition comprising a mixture containing charcoal, silica sand, bentonite, zinc oxide, fireclay, calcium carbonate, refractory concrete, monobasic sodium phosphate, ammonium sulphate, borax, linseed oil and lead-free gasoline.

2. A composition as claimed in Claim 1, containing the charcoal, silica sand and zinc oxide in approximately equal quantities by weight and, respectively related to the total quantity of all solid components of the mixture, each about 5 to 10% by weight bentonite, fire-clay, calcium carbonate, refractory concrete, monobasic sodium phosphate and ammonium sulphate and about 1 to 2% by weight borax, the content of the mixture of linseed oil and lead-free gasoline being about 15 to 25% by weight of the total quantity of all solid components of the mixture.

3. A composition as claimed in Claim 1, characterised in that it contains the components in the following proportions 400 to 600 parts by weight charcoal, 400 to 600 parts by weight silica sand, 200 to 300 parts by weight bentonite, 400 to 600 parts by weight zinc oxide, 40 to 60 parts by weight borax, 150 to 250 parts by weight fireclay, 120 to 180 parts by weight calcium carbonate, 200 to 270 parts by weight refractory concrete, 150 to 250 parts by weight monobasic phosphate of sodium, 120 to 180 parts by weight ammonium sulphate and 600to 900 parts by volume of each linseed oil and lead-free gasoline.

4. A composition as claimed in any preceding Claim containing the components in about the following proportions: 500 parts by weight charcoal, 500 parts by weight silica sand, 250 parts by weight bentonite, 500 parts by weight zinc oxide, 50 parts by weight borax, 200 parts by weight fireclay, 150 parts by weight calcium carbonate, 235 parts by weight refractory concrete, 200 parts by weight monobasic phosphate of sodium, 150 parts by weight ammonium sulphate, and about 750 mls of each of linseed oil and lead-free gasoline for every 2735 grs total of the foregoing components.

5. A composition as claimed in any preceding Claim having a density of about 40 Baume or more.

6. A composition as claimed in any preceding Claim further containing thinner as a drying time reducer.

7. A composition as claimed in Claim 6 containing sufficient thinner to reduce the drying time by about 50%, preferably 250 mls thinner per litre of prepared mixture.

8. A composition according to any preceding Claim in which both the charcoal and the silica sand are ground down to a mesh size appropriate for the application desired, the composition having a liquid consistency appropriate for application desired, the composition having a liquid consistency appropriate for application as a paint or a semi-liquid plaster-like consistency.

9. A method of making a composition as claimed in any preceding Claim in which the dry components are mixed together in a dry state, preferably at a temperature of from 1 to 10"C, and then the liquid components are mixed therewith.

10. A process of imparting a protective coating layer or impregnation to a substrate which comprises applying thereto a composition as claimed in any of Claims 1 to 9 and drying it or allowing it to dry.