GB2418924A

GB2418924A - Weathered-effect composition

Info

Publication number: GB2418924A
Application number: GB0517958A
Authority: GB
Inventors: Christopher William Joh Cottam; John Francis Toft
Original assignee: LIQUID PRODUCTS Ltd
Current assignee: LIQUID PRODUCTS Ltd
Priority date: 2004-09-02
Filing date: 2005-09-02
Publication date: 2006-04-12
Anticipated expiration: 2025-09-02
Also published as: GB0419489D0; GB2418924B; GB0517958D0

Abstract

A composition for application to a structural substrate surface for imparting thereto a weathered appearance comprises a water-soluble resin binder, a weathering-effect pigment, a surface penetrating agent and a diluent. The water-soluble resin binder may be a silane modified styrene-butadiene latex, the pigment may be carbon black and the surface penetrating agent may be a non-ionic surfactant.

Description

24 1 8924 P105032GB-1 Weathered-Effect Composition This invention relates

to composition for providing an weathered appearance to a structural building substrate.

It is frequently the case that, in construction of an extension to a property, or in carrying out a repair involving replacement structural parts, the external surface of the new structure does not blend aesthetically with the original because the original has been exposed to the elements and has attained a "weathered" appearance.

It is an object of the present invention to provide a composition which can be applied to new structural surfaces to invest them with a weathered appearance.

In one aspect, the invention provides a composition for application to a structural substrate surface for imparting thereto a weathered appearance, the composition comprising a water-soluble resin binder, a weatheringeffect pigment, a surface penetrating agent and a diluent.

By "structural substrate surface" in this specification is meant the surface of a wall, whether constructed of concrete, bricks or masonry, including rendered surfaces. The term also includes roofing tiles and slates. Such materials are inherently porous.

In compositions according to the invention, the resin acts as a binder for the pigment during storage and on application to a surface, and to cause the pigment to adhere to the surface after application. In contrast to a conventional paint formulation, however, the pigment does not form an opaque film on the surface but, rather, forms a transparent or at least a translucent coating or film, the pigment particles being individually spaced apart with areas of cured resin film therebetween. The resin may comprise a water-soluble acrylic resin, preferably a styrene-butadiene latex which, to promote substrate adhesion and prevent flaking or peeling with age, is preferably silane-modified. The ratio of silane to styrene-butadiene may be in the range 1:2 to 1:10 by weight, preferably from 1:2 to 1:5, for

example 1:3.

The purpose of the pigment is to mimic the effect of naturally-occuring airborne colorants in darkening the substrate without substantially altering the hue thereof. It has been found that carbon black, preferably microfined, is a suitable pigment, optionally in combination with a minor amount of one or more other pigments or extenders. The pigment volume concentration should be such as to provide the desired effect in darkening the substrate without altering the texture or hue thereof, to simulate the appearance of ageing and to allow the ageing process to continue naturally. The pigment should preferably be finely ground and dispersed in the resin binder so as to provide a uniform darkening effect and also to assist in penetration of the substrate beneath the external surface thereof.

The penetration agent preferably comprises a wetting agent, for example a surfactant which may be anionic, cationic or neutral, for conditioning or preparing the substrate surface to allow penetration of the resin binder carrying dispersed pigment. Penetration may take place by capillary action through the pores of the substrate, or as a result of osmotic pressure, for example. The surfactant is preferable non-ionic, for optimum compatibility with other ingredients.

The diluent is preferably water but may alternatively or additionally comprise a water-soluble polar organic compound which is substantially inert to the resin and which has a boiling point such that it will tend to evaporate on storage but, having been applied to the substrate, will then enhance the penetration ability and be subject to evaporation as a result of the extended surface area of the substrate and from being exposed to ambient atmospheric condition. Alcohols and ketones are examples of organic diluents or co-diluents which, provided having a suitable boiling point, may be contemplated for use in the present invention. Ethers may also be used, for example akylene glycol ethers such as dipropylene glycol ether.

Preferably, compositions according to the invention also include one or more preservatives, for example an antibacterial agent to prevent or inhibit the growth of mould or bacteria.

However, it is desirable for fungal growth not to be retarded, whereby further weathering or ageing will occur at essentially the same rate as on surrounding or adjacent surfaces.

Compositions according to the invention may also include an anti-settling agent and a thickening agent, as known in the surface coatings art. For example, polyacrylamides may be used for thickening purposes and bentonite clay as an anti-settling agent.

Compositions according to the invention may have the following general formulation, all percentages being by weight: Silane-modified styenebutadiene resin 4 -lO To Carbon black 0.5-2% _.

Thickemng agent (if present) _ 0.5-2% Anti-settling agent(ifpresent) 1 0. 1-5% Surfactant I 0.5-2% Water balance Compositions according to the invention may be applied by brush, sponge or by a spray-gun and can be diluted with water before application to provide a lighter effect or applied in further coats to provide a darker effect. An anti-blocking agent such as urea may be added between 1 and 5% by weight, preferably 23%, to formulations for application by spray-gun, to prevent blocking of the spray nozzle.

One formulation, by way of example only, is as follows: Silane-modified (1:3) styrene-butadiene resin 6% Microfined carbon black 1% Nonionic surfactant I 1 %_ Water 92% Dispersion of the pigment in the binder can take place in a ball mill optionally without or with only a proportion of the water to provide a millbase, water being added subsequently to the final formulation requirements.

Claims

Claims 1. A composition for application to a structural substrate surface

for imparting thereto a weathered appearance, the composition comprising a water-soluble resin binder, a weathering-effect pigment, a surface penetrating agent and a diluent.
2. A composition according to claim 1, in which the resin comprises a water-soluble acrylic resin.
3. A composition according to claim 2, in which the resin comprises a styrene-butadiene latex.
4. A composition according to claim 3, in which the resin is silanemodified.
5. A composition according to claim 4, in which the ratio of silane to styrene-butadiene is in the range 1:2 to 1:10 by weight.
6. A composition according to any preceding claim, in which the pigment comprises carbon black.
7. A composition according to any preceding claim, in which the penetration agent comprises a non-ionic surfactant.
8. A composition according to any preceding claim, in which the diluent is water optionally including a water-soluble polar organic compound.
9. A method of imparting a weathered appearance to a structural substrate surface, the method comprising applying to the surface a composition according to any preceding claim and allowing the composition to dry or cure.