GB2268098A

GB2268098A - Fire retardant anti-graffiti facing for walls and similar surfaces

Info

Publication number: GB2268098A
Application number: GB9312848A
Authority: GB
Inventors: Patrick Richard Rawlins
Original assignee: Hubdean Ltd
Current assignee: Hubdean Ltd
Priority date: 1992-06-24
Filing date: 1993-06-22
Publication date: 1994-01-05
Anticipated expiration: 2013-06-22
Also published as: GB2268098B; GB9312848D0; GB9213422D0

Abstract

Coating a wall or similar surface with a fire retardant facing is effected by firstly the application thereto of a primer and sealing bonding agent such as a resin which may contain a proportion of aggregate such as china clay. A further coating composition, e.g. in paste form is applied and textured, followed by a finishing coating.

Description

Title: Fire retardant anti-graffiti facing for walls and similar surfaces The present invention relates to a fire retardant facing for walls and similar surfaces.

in the testing of a facing to ensure that it meets the relevant British Standards for resistance to fire the facing is applied to a non-combustible, standard substrate. However, in use such facings are not applied to non-combustible substrates. Normally, such facings are applied over one or more layers of paint with the result that the combination of layers does not meet the relevant British Standards.

The present invention seeks to provide an improved fire retardant facing.

Accordingly, the present invention provides a method of coating a substrate such as a wall or other surface with a fire retardant facing comprising: (a) applying a first layer of a priming and sealing bonding agent to the substrate in order to provide an adhesive coating thereon; (b) applying a second layer of a coating composition comprised of setting and filler materials and binding and hardening constituents to provide, on setting, a hard surface resistant to indentation; (c) texturing the surface of said second layer prior to hardening thereof; and (d) after hardening of said second layer, applying to the textured surface of said second layer a third layer of a finishing coating.

The present invention also provides a fire retardant facing for a substrate such as a wall or other surface comprising: a first layer forming a priming and sealing bonding agent; and a second layer of a coating composition comprised of setting and filler materials and binding and hardening constituents for providing a hard surface resistant to indentation.

Advantageously, the facing has a third layer of a finishing coating.

In a preferred form of the invention the priming and sealing bonding agent is a PVA resin. Advantageously, the second layer includes a PVA resin.

Preferably, the third layer comprises organic and inorganic pigments disbursed in a mixture of acrylic resin and aromatic hydrocarbons. This forms a hard finish and provides an antigraffiti effect. The aromatic hydrocarbons are conveniently 30% to 40% by weight of the finish coating.

An appropriate first layer of primer and sealing coating is applied to the substrate in any suitable manner such as brush, roller or spray application. In the case of flat or curved panels of chipboard, hardboard, asbestos, wood or metal the coating may consist of an oleo-resinous binder and an alkaliresisting mica based pigment together with suitable solvents.

The coating preferably contains a proportion of aggregate such as china clay, preferably not exceeding 10* by weight. Other resin based binding and sealing agents may be employed such as polyvinyl acetate or butadiene styrene. The coating seals the substrate (e.g. against dampness) and provides specific and mechanical bonding adhesive characteristics for the subsequent application of a second layer of a further coating composition i.e. after oxidation or drying of the first layer has taken place to an adhesive condition.

The second layer may be applied as a paste to the first layer in any suitable manner such as by brush, roller, spray or trowel application or by mechanical means or may be of a consistency such that it can be poured onto the surface to a required thickness, e.g. by skimming off to the desired depth.

In the case of a paste the composition is mixed to the appropriate consistency of a semi-viscous cake mix. The second layer is a passive barrier which is relatively thick, e.g. 4mm to 6mm, and protects the first layer and the substrate from heat and flames.

An example of a typical second layer composition consists of a hemi-hydrate gypsum plaster, a water soluble or dispersable binder such as gelatine, polyvinyl acetate or vinyl acetate/ethylene copolymer and a filler such as ground calcine, clay or alumina. Exfoliated mica is also included as a hardening and reinforcing agent. Water retention agents such as cellulose ethers are incorporated as well as rheology modifiers.

An example of the proportions of the constituents of the second layer are as follows: Hemi-hydrate gypsum plaster 23.0% by weight Ground calcite and other fillers 69.2% by weight Binders 3.0% by weight Exfoliated mica 4.5% by weight Additives (water retention agents, rheology modifiers, etc.) 0.3% by weight Colouring agents may be added to the composition if required.

The desired viscosity of the composition and depth of application will vary depending upon the degree of texturing which is subsequently effected on the surface of the second layer. Prior to application, the composition is preferably dyed with an appropriate water soluble colouring material related to at least the approximate shade of the colour of the finished facing.

After application of the second layer and any partial drying thereof as necessary, it is then subject to texturing such as by means of a hair or rubber stippler or roller to produce a relief surface especially in sharp relief. Preferably a design or pattern is applied by the texturing operation.

Various tools or mechanical means may be used for effecting the texturing in relief with appropriate artistic expertise as regards form and pattern.

As drying or evaporation continues, setting and hardening of the second layer takes place which, dependent on temperature and humidity, is normally completed within a period of four to twelve hours or thereabouts. The hard textured and preferably patterned surface of the second layer is then sprayed or roller applied with a third layer forming a finish coating comprising organic and inorganic pigments dispersed in a mixture of acrylic resin and aromatic hydrocarbons. The aromatic hydrocarbons are preferably 30% to 40% by weight of the third layer.

As well as providing the finished appearance of the facing, the finish coating also protects the second layer, provides durability and allows the second layer to continue to harden and by appropriate application can make the facing weather resistant for outside use.

The above-described facing has been tested and found to meet B.S. 476, parts 6 and 7 fire propagation and surface spread of flame tests when applied over a 20 coat paint system consisting of a combination of paint types freely applied by brush, and of an unthinned consistency, in accordance with the manufacturer's instructions. An advantage of the above described facing is that it can be renewed after five to seven years by simply adding a new facing over the old facing without downgrading the resulting surface with regard to BS476. With hitherto known facings renewing the facings simply by covering the old facings with new facings has resulted in a downgrading of the resulting surfaces with regard to BS476 and in order to maintain the fire rating of the surfaces it has been necessary to remove the old facings before applying the new facings.

The hard textured and patterned surface of the finished facing is such that it cannot readily be written on or otherwise marked with a writing instrument such as a felt tipped pen, whilst its hardness is resistant to indentation such as scratching or cutting and which even if effected is hardly apparent where the dyed colour of the second layer is substantially similar to that of the third layer.

Whereas the finished facing can be effectively defaced by the use of aerosol paint sprayers, the problem can be readily overcome by obliterating the marking rather than attempting to remove it by conventional means. Since most of the constituents in paint used in practically all aerosol graffiti are similar, such obliteration can be effectively carried out by aerosol spraying or rolling over the graffiti with the acrylic based finishes of a colour that matches the metallic or plain finish coating of the facing. This can be readily effected with little or no skill by a few spraying passes of the aerosol or roller over the graffiti. Owing to the fact that similar finishes are used, that of the graffiti or similar marking is partially dissolved by the solvent of the superimposed spray paint application due to its reversible nature and thus mixes with the latter, at the same time filling up or rendering inconspicuous any cuts or scratches.

As will be appreciated from the foregoing, not only is graffiti marking by pen or similar application made difficult and thus discouraged, but also paint spray marking can be readily and quickly overcome by obliteration in the manner described above so as to restore the facing to its original condition.

The textured or patterned surface of the facing reflects light in numerous directions and thus facilitates the concealment of any patches when obliteration or touching up is necessary.

A further property of the finished facing is that cuts or scratches tend to have a self closing or "healing" action after restorative spray application of appropriate acrylic based paint.

Whereas the facing can be applied to an existing wall or similar surface, its use can be facilitated by application in a matching manner to panels or cladding which can be subsequently erected or fitted on site. Thus a continuous mural design can be provided in an attractive and aesthetically appealing manner.

Claims

1. Method of coating a substrate such as a wall or other surface with a fire retardant facing comprising: (a) applying a first layer of a priming and sealing bonding agent to the substrate in order to provide an adhesive coating thereon; (b) applying a second layer of a coating composition comprised of setting and filler materials and binding and hardening constituents to provide, on setting, a hard surface resistant to indentation; (c) texturing the surface of said second layer prior to hardening thereof; and (d) after hardening of said second layer, applying to the textured surface of said second layer a third layer of a finishing coating.

2. A method as claimed in claim 1 wherein the first layer is resin based.

3. A method as claimed in claim 2 wherein the first layer comprises polyvinyl acetate or butadiene styrene.

4. A method as claimed in claim 1 wherein the first layer has a mica content.

5. A method as claimed in claim 4 wherein the first layer includes an alkali-resisting mica based pigment.

6. A method as claimed in claim 5 wherein the first layer has an oleo-resinous binder.

7. A method as claimed in any preceding claim wherein the first layer contains an aggregate not exceeding 10% by weight.

8. A method as claimed in claim 7 wherein said aggregate is in the range 3% - 5% by weight.

9. A method as claimed in claim 7 or 8 wherein said aggregate is china clay.

10. A method as claimed in any preceding claim wherein the second layer contains a PVA resin as a binding agent.

11. A method as claimed in any of the preceding claims wherein the filler material of the second layer comprises one or more materials selected from the group comprising china clay, whiting and alumina.

12. A method as claimed in any preceding claim wherein the second layer includes mica as a hardening and strengthening agent.

13. A method as claimed in claim 12 wherein the mica is exfoliated mica.

14. A method as claimed in any preceding claim wherein the resin base of the second layer comprises gum arabic, polyvinyl acetate or butadiene styrene.

15. A method as claimed in any preceding claim wherein the second layer contains colouring matter or pigmentation approximating in colour to that of the third layer.

16. A method as claimed in any preceding claim wherein the setting material of the second layer comprises a plaster material.

17. A method as claimed in claim 16 wherein said plaster material comprises partially dehydrated gypsum.

18. A method as claimed in any preceding claim wherein the third layer comprises organic and inorganic pigments.

19. A method as claimed in claim 18 wherein the organic and inorganic pigments are dispersed in a mixture of acrylic resin and aromatic hydrocarbons.

20. A method as claimed in claim 19 wherein said aromatic hydrocarbons are in the range 30% to 40% by weight of the layer.

21. A method as claimed in any preceding claim wherein the second layer is in the range 4mm to 6mm thick.

22. A fire retardant facing comprising: a first layer ofa priming and sealing bonding agent; and a second layer of a coating composition comprised of setting and filler materials and binding and hardening constituents forming a hard surface resistant to indentation.

23. A facing as claimed in claim 22 having a third layer of a finishing coating.

24. A facing as claimed in claim 23 wherein the first layer is resin based.

25. A facing as claimed in claim 23 wherein the first layer comprises polyvinyl acetate or butadiene styrene.

26. A facing as claimed in claim 23 wherein the first layer has a mica content.

27. A facing as claimed in claim 26 wherein the first layer includes an alkali-resisting mica based pigment.

28. A facing as claimed in claim 27 wherein the first layer has an oleo-resinous binder.

29. A facing as claimed in any of claims 22 to 28 wherein the first layer contains an aggregate not exceeding 10% by weight.

30. A facing as claimed in claim 29 wherein said aggregate is in the range 3% - 5% by weight.

31. A facing as claimed in claim 29 or 30 wherein said aggregate is china clay.

32. A facing as claimed in any of claims 22 to 31 wherein the second layer contains a PVA resin as a binding agent.

33. A facing as claimed in any of claims 22 to 32 wherein the filler material of the second layer comprises one or more materials selected from the group comprising china clay, whiting and alumina.

34. A facing as claimed in any of claims 22 to 33 wherein the second layer includes mica as a hardening and strengthening agent.

35. A facing as claimed in claim 34 wherein the mica is exfoliated mica.

36. A facing as claimed in any of claims 22 to 35 wherein the resin base of the second layer comprises gum arabic, polyvinyl acetate or butadiene styrene.

37. A facing as claimed in any of claims 22 to 36 wherein the second layer contains colouring matter or pigmentation approximating in colour to that of the third layer.

38. A facing as claimed in any of claims 22 to 37 wherein the setting material of the second layer comprises a plaster material.

39. A facing as claimed in claim 38 wherein said plaster material comprises partially dehydrated gypsum.

40. A facing as claimed in any of claims 23 to 39 wherein the -third layer comprises organic and inorganic pigments.

41. A facing as claimed in claim 40 wherein the organic and inorganic pigments are dispersed in a mixture of acrylic resin and aromatic hydrocarbons.

42. A facing as claimed in claim 41 wherein said aromatic hydrocarbons are in the range 30% to 40% by weight of the layer.

43. A facing as claimed in any of claims 22 to 42 wherein the second layer is in the range 4mm to 6mm thick.

44. A method as claimed in claim 1 and substantially as hereinbefore described.

45. A facing as claimed in claim 22 and substantially as hereinbefore described.