GB2438466A

GB2438466A - Surfacings for bricks and tiles

Info

Publication number: GB2438466A
Application number: GB0610270A
Authority: GB
Inventors: John William Carson
Original assignee: Individual
Current assignee: Individual
Priority date: 2006-05-24
Filing date: 2006-05-24
Publication date: 2007-11-28
Also published as: GB0610270D0

Abstract

A sacrificial aggregate for use in the surface decoration of clay mineral bricks, tiles and similar items, comprised of three essential ingredients intimately mixed together; a porous solid carrier oxide or oxide providing species; a water soluble or suspendable fluxing oxide or oxide providing species; and a water soluble or suspendable pigmenting oxide or oxide providing species. This sacrificial aggregate can be made by absorbing the fluxing and pigmenting species onto the carrier species, followed by draining, optional dying and size modification. This sacrificial aggregate is used as an indenting surface additive on unfired clay mineral bricks, tiles and similar items. The resulting modified bricks are then processed by conventional calcination. The resulting fired bricks have improved textural and pigmentary properties by virtue of amygdales in their surfaces. When used in conventional building systems such bricks display an improved aesthetic effect.

Description

IMPROVED SURFACINGS FOR BRICKS AND TILES

The present invention relates to a process for improving the surface of bricks and tiles and other similar fired clay mineral ceramics.

This process for improving the surface of fired clay mineral ceramics, such as bricks and tiles, is based on the use of a range of novel sacrificial aggregates. The use of these sacrificial aggregates on the surface of clay mineral bricks which are to be fired considerably improves the surface texture and colour of the fired ceramic articles.

The manufacture of bricks, tiles and similar articles from clay mineral mixtures, that is brick earths, via a calcination process to produce fired ceramic structural items is well known. It is known globally as the brick making industry. In this context the term brick making is intended to cover all such fired ceramic structural items including bricks, tiles, blocks, payers and all other similar items.

Whereas many brick earths can be used by the brick making industry to produce structurally satisfactory bricks the aesthetic qualities of many such items so produced is unsatisfactory.

By unsatisfactory aesthetics, in this context is meant, dull coloured, uninterestingly textured, articles that have little artistic merit when constructed as walls or roofs or pavements.

However, it is recognised that the products of the brick industry are commodities and have therefore to be manufactured at a low price.

The present invention provides a novel process by which the aesthetics of bricks can be economically improved. 2.

This novel process is a surface treatment wherein a sacrificial aggregate is indented into shaped brick earth items prior to catcination.

The sacrificial aggregates are specifically formulated to provide chemicals which react during calcination to produce the desired improvements to the surface of the fired brick. In the process the sacrificial aggregate ceases to exist as a separate physico-chemical entity and is absorbed into the brick earth structure. The resulting aesthetic effect is to produce localised centres of texture and colour on the surface of the fired ceramic item. These localised centres of texture and colour are visibly differentiated from the background hue and texture of the brick and thereby add visual effect.

It is an important feature of the present invention that the use of the novel sacrificial aggregate only alters the surface of treated bricks. Both the body of the fired bricks and the manufacturing process by which they are produced remains essentially unchanged.

Many previous attempts have been made to modify the brick making process so as to produce bricks with greater aesthetic appeal. Among these are processes for glazing bricks, pigments for changing the body colour of bricks, and shaping techniques to improve the surface texture of bricks. However, all such processes significantly increase the manufacturing costs of such items.

Also, it may be noted that the above individual methods for improving the aesthetics of fired ceramic structural items only effect changes to either colour or texture.

It is an important feature of the present invention that the use of the novel sacrificial aggregates effects both colour and texture of the surface of bricks. It is partly because of this dual effect that the surface treatment defined herein is economic in use. 3.

The invention described herein provides for the decoration of brick surfaces, in terms of both colouring and texturing, via the use of a novel sacrificial aggregate which is indented into the surfaces of unfired clay mineral bricks and subsequently fired into their surfaces by conventional kilning techniques. The result is a decorated brick with localised areas of colour and texture on the surfaces of the otherwise unchanged fired brick.

The basis of the present invention is the recognition that it is possible to carry out chemical reactions on the surface of clay mineral bricks during their firing, that is calcination, and that the reaction products of these chemical reactions can provide aesthetic surface decoration.

The chemical reactions referred to are, by nature, thermo chemical reactions, that is high temperature or ceramic reactions. Typically these involve reactions between oxidic materials such as take place between the oxides of alkali metals and alkali earths together with other metal oxides and transition metal oxides. Additionally, these reactions may take place between oxides and oxide producing species, that is chemicals that yield oxides during calcination.

Specifically, the present invention is based on the recognition that normally nert chemical species can be activated and reacted, on the surface of bricks during calcination, by the addition of fluxing oxides. Such normally inert oxides will be referred to as carriers.

Typical of a carrier substance, is an oxide of an alkaline earth element, but may also be an oxide of aluminium, silicon, iron or titanium.

In this context a fluxing oxide is usually an alkali metal oxide, but may also be an oxide of phosphorous, boron or lead. Such reactive oxides will be referred to as fluxing oxides. 4.

It has also been recognised that oxides associated with ceramic colours may advantageously be involved in these brick surface thermo-chemical reactions.

These various thermo-chemical reactions may be facilitated on the surface of a brick during calcination by the incorporation in the brick surface of a range of novel sacrificial aggregates as defined herein.

I may broadly define my invention as a sacrificial aggregate based on a carrier oxide or carrier oxide providing species together with a fluxing oxide or fluxing oxide providing species in conjunction with a colouring oxide or colouring oxide providing species.

The novel sacrificial aggregate defined in the present invention is a composition of matter produced when three essential material ingredients are intimately mixed and provided together in the form of a solid aggregate.

The three essential ingredients will now be defined: The first essential ingredient is an oxide or oxide providing species of a normally stable nature.

Examples of such oxides are; those of alkali earth elements such as magnesium, calcium, barium and also aluminium, silicon and titanium. These may be provided as oxides or species that produce oxides during calcination such as hydroxides, suiphates, chlorides, nitrates, carbonates or organic satts. These alkali earth and other normally stable oxides may be used singly or in combinations.

The role of such substances as alkali earth or oxides of aluminium, silicon and titanium is that they act as carriers. In this context a carrier oxide functions by carrying the fluxing and pigmenting oxides into chemical reaction with, on and in the brick surface. 5.

The second essential ingredient is an oxide or oxide providing species of a fluxing type. Fluxing, in this context means, the reduction of the normal melting point of a stable material. Examples of such oxides are; those of alkali metals such as lithium, sodium, potassium and also boron, phosphorous and lead. These alkali metal and other fluxing oxides may be used singly or in combinations.

The third essential ingredient is an oxide or oxide providing species of a pigmentary type.

Pigmentary, in this context means, capable of providing colours in the fired ceramic composition. Examples of such oxides are; those of transition metals such as titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper and cadmium. These transition metal and other pigmentary oxides may be used singly or in combinations.

In addition to these essential materials the novel sacrificial aggregate may contain other materials that serve the purpose of modifying the stability of stable oxides, the fluxing of fluxing oxides and the pigmentation of the pigmentary oxides.

The novel sacrificial aggregate is the result of intimately blending and or mixing the three essential materials together. The sacrificial aggregate may therefore be defined as a combination of a carrier oxide or carrier oxide provider, plus a fluxing oxide or fluxing oxide provider, plus a pigmentary oxide or pigmenting oxide provider.

The preferred method by which the novel sacrificial aggregate may be manufactured will now be described: The mixing and or blending of the three essential material ingredients for the preparation of the novel sacrificial aggregate may be conveniently achieved by absorbing the fluxing and pigmenting components onto the carrier component. 6.

Advantageously the carrier component may be an absorbent solid, that is a solid into which water and solubilised salts can be absorbed. The fluxing and pigmentary components, in the form of aqueous solutions, may conveniently be absorbed onto the carrier component, simply by stirring the absorbent solid into the mixed salt solution. Once absorption has taken place excess solution may be drained and the moist form of the novel sacrificial aggregate may be dried by any conventional means such as tray drying in a warm air oven. After drying the aggregate may be further comminuted or agglomerated if required, using conventional techniques for achieving such size modification.

The above method for manufacturing the novel sacrificial aggregate is my preferred method, but, it is only an example. Other conventional ways of contacting, absorbing and entrapping soluble or suspended salts onto and into an absorbent solid may also be used.

It is a feature of the present invention that the novel sacrificial aggregate contains both the fluxing and pigmenting components evenly mixed and distributed throughout the absorbent carrier component.

The method by which the novel sacrificial aggregate is applied to unfired bricks will now be described: The novel sacrificial aggregate is used by being applied to the outer surface or surfaces of unfired clay mineral bricks and similar items. This application may be achieved during conventional brick shaping. Conventionally, bricks are shaped by either moulding or extruding processes. The terms moulding and extruding are well understood in the brick industry. The novel sacrificial aggregate may be added to either moulds or extruders in such ways as are convenient to provide and produce the effect of indenting or incorporating the said aggregates in the surface layers of the shaped brick. 7.

The method by which the aesthetic effect, based on the incorporation of the novel sacrificial aggregate, is achieved will now be described: Shaped clay mineral bricks or other similar items, containing the novel sacrificial aggregates in the surface layers are conventionally calcined. Conventionally, bricks are calcined at a temperature and for a time sufficient to develop ceramic bonding of the brick earth from which the bricks are primarily composed. The temperature and time of calcination must be determined for each individual brick earth, and must take account of the calcination technique to be used. Bricks may be calcined in clamps, tunnel kilns or other types of kilns. The terms clamps and kilns, including tunnel kilns are well understood in the brick industry.

It is a feature of the present invention that the incorporation of the novel sacrificial aggregate in bricks can be achieved by conventional calcination without the need to change the method of calcination, the temperatures involved or the duration, that is the time involved in the calcination.

The application of conventional calcination processes to bricks containing the novel sacrificial aggregate in their surfaces, produces the aesthetic improvements which are a desired feature of bricks produced via the present invention.

The aesthetic brick surface improvement will now be described: The aesthetic surface modification achieved via the use of the novel sacrificial aggregate involves both hue and textural effects. Indeed, it is a feature of the present invention that this dual effect may be achieved via the use of one single addition of the sacrificial aggregate. 8.

This combined textural and pigmentary effect may be described as the modification of the brick surface, by the incorporation of amygdales. In this context an amygdale is a vesicle partially filled and or lined with a glass ceramic material. The terms amygdale and vesicle are well understood in the field of geology and in the manufacture of natural stone items such as building blocks. Glass ceramics, as are produced within the vesicles, are substances composed of ceramic crystals within glassy compositions.

These amygdales provide both the textural and pigmentary surface decoration to bricks treated as described, with the novel sacrificial aggregate, Both the colour and texture of the amygdales produced can be controlled and determined by the chemical constituents used in the preparation of the novel sacrificial aggregate.

I have carried out extensive research into the production of aesthetic amygdales in the surface of clay mineral bricks by calcination of embedded novel sacrfticial aggregates. This research has led to the establishment of a standardised approach to the formulation of such sacrificial aggregates. The following initial formulation is independent of the specific carrier oxides, fluxing oxides and pigmenting oxides used: Carrier oxides 30% to 99% by weight.

Fluxing oxides 0.5% to 30% by weight.

Pigmenting oxides 0.1% to 50% by weight.

Within the above ranges the following are preferred examples of specific sacrificial aggregates: 9.

Example 1: An economic deep red low gloss amygdaloidal sacrificial aggregate: Carrier oxide; Calcia 50% to 99% by weight. Provided by calcium carbonate aggregate.

Fluxing oxide: Sodium oxide 0.5% to 5% by weight. Provided by sodium silicate solution.

Pigmentary oxide; Iron oxide 1% to 40% by weight. Provided by ferrous sulphate solution.

Example 2: A bright deep purple blue medium gloss amygdaloidal sacrificial aggregate: (percentages by weight).

Carrier oxides; Calcia 30% to 50%, Magnesia 30% to 50%. Provided by dolomitic limestone aggregate.

Fluxing oxides; Potassium oxide 1% to 5%, Phosphorous oxide 1% to 5%. Provided by potassium phosphate solution.

Pigmentary oxide; Cobalt oxide 0.5% to 10%. Provided by cobalt sulphate solution.

Example 3: A pastel apple green high gloss amygdaloidal sacrificial aggregate: Carrier oxide; Titania 50% to 99% by weight. Provided by titania dioxide aggregate.

Fluxing oxide; Lead oxide 2.0% to 10% by weight. Provided by lead acetate solution.

Pigmentary oxide; Copper oxide 0.5% to 10% by weight. Provided by copper sulphate solution.

The above three formulations are only examples of a wide range of formulations which I have researched and developed for the production of aesthetic sacrificial aggregates.

I may describe my invention in the following three parts (A,B and C): A. A novel composition of matter.

A novel composition of matter which is a sacrificial aggregate for application to clay mineral bricks by embedding in surfaces, based on: 10.

A carrier oxide or oxide providing species.

A fluxing oxide or oxide providing species.

A pigmenting oxide or oxide providing species.

B. A novel manufacturing process.

A novel and economic process, that is a method of manufacturing the sacrificial aggregates, based on the impregnation of porous carrier oxides or oxide providing species with a water based solution of fluxing and pigmenting oxide salts. The fluxing and pigmenting oxide salts become dispersed throughout the carrier oxide or oxide providing species. The sacrificial aggregate may then be drained and dried.

C. A novel range of products.

A range of novel and aesthetic fired clay mineral brick surface effects achieved via the embedding of the sacrificial aggregate into the surface of the unfired brick, and based on the production during calcination of pigmented and textured amygdales.

The advantages of the present invention will now be defined: The sacrificial aggregates are simple and economic to prepare. Many can be successfully based on waste materials such as waste minerals, and chemical co products for example gypsum.

Dftferent sizes and size ranges of sacrificial aggregate can conveniently be made. These can range from dusts to gravel sized particulates. 11.

Relatively low concentrations of otherwise expensive pigmenting oxides or oxide providers need to be used to produce aesthetic amygdales.

The process by which the sacrificial aggregate is made is essentially low cost because it is a low energy approach which does not, in itself, require high temperature treatment.

The method by which the sacrificial aggregate is applied to clay mineral bricks is essentially low cost and within conventional manufacturing scope.

The brick calcination process is unchanged by the use of the sacrificial aggregate and therefore lies within conventional manufacturing scope.

The aesthetic effects produced by the formation of amygdales in the calcined surface of bricks is such that it significantly adds to the value of such bricks.

Taken together the above advantages constitute a significant improvement in the process by which clay mineral bricks are decorated.

The reader's attention is directed to all papers and documents which are filled concurrently with or previous to this specification in connection with this application and which are open to public inspection with this specification, and the contents of all such papers and documents are incorporated herein by reference. All of the features disclosed in this specification (including any accompanying claims, abstract and drawings) and/or all of the steps of any method or process so disclosed, may be combined in any combination, except combinations where at least some of the features and/or steps are mutually exclusive. 12.

Each feature disclosed in this specification (including any accompanying claims, abstract and drawings] may be replaced by alternative features serving the same, equivalent or similar purpose, unless expressly stated otherwise. Thus, unless expressly stated otherwise, each feature disclosed is one example only of a generic series of equivalent or similar features.

The invention is not restricted to the detail of the foregoing embodiment(s). The invention extends to any novel one, or any novel combination, of the features disclosed in this specification [including any accompanying claims, abstract and drawings], or to any one or more novel combination of the steps of any method or process so disclosed. 13.

Claims

CLAIMS

1. A sacrificial aggregate for incorporation into the surfaces of clay mineral bricks, tiles and similar items to be calcined, comprising in combinations: a] A carrier oxide or oxide providing species.

b) A fluxing oxide or oxide providing species.

c] A pigmenting oxide or oxide providing species.

2. A sacrificial aggregate for the surface decoration of clay mineral bricks, tiles and similar items, according to claim I, wherein the proportions by weight percentage of the components to each other are: a] Carrier oxides or oxide providers 30% to 99%.

b) Fluxing oxides or oxide providers 0.5% to 30%.

c] Pigmenting oxides or oxide providers 0.1% to 50%.

3. A sacrificial aggregate according to claims I and 2, wherein the carrier oxide or oxide provider is magnesia, calcia, baria, alumina, silica or titania, or a corresponding salt or a combination thereof.

4. A sacrificial aggregate according to claims I and 2, wherein the fluxing oxide or oxide provider is a chemical substance based on lithium, sodium, potassium, boron, phosphorous, or lead or a combination thereof.

5. A sacrificial aggregate according to claims I and 2, wherein the pigmenting oxide or oxide providers is a chemical substance based on titanium, vanadium, chromium, manganese, iron, cobalt, nickel, copper or cadmium or a combination thereof. 14.

6. A method or process by which a sacrificial aggregate according to claims I to 5 can be made by absorbing aqueous solutions or water bourn suspensions of fluxing oxides or oxide providers plus pigmenting oxides or oxide providers onto a porous form of solid carrier oxide or oxide provider, optionally followed by draining and or drying.

7. A method or process by which aesthetically improved bricks can be manufactured by the incorporation of a sacrificial aggregate, defined according to claims I to 6, into the surface of the shaped but unfired brick earth, and the subsequent conventional calcination of the shaped brick so treated.

8. A method or process by which aesthetically improved bricks can be manufactured via a process substantially as defined according to claims I to 7 wherein textured and coloured amygdales are formed in the brick surface.

9. A range of aesthetically improved bricks manufactured according to claims I to 8.

10. A system for improving the aesthetics of walls, roofs and pathways built from calcined clay mineral bricks, tiles and similar items manufactured substantially as described herein.