AU2005225465B2 - Saccharide/cement coating compositions - Google Patents

Description

WO 2005/092990 PCT/AU2005/000448 Saccharide/Cement Coating Compositions Technical Field This invention relates to surface coating compositions that include 5 saccharide compounds as a component of the binder composition of the coating. The invention also relates to methods of preparing coating compositions containing saccharide compounds as components of the binding of the coating. 10 Background of the Invention Paints or coating compositions have been known for thousands of years, from at least the times of the ancient Egyptians. Paints consist of three basic ingredients; a binder, pigments or colourants and, additives or diluents. The additives include extender or filler particles that influence the mechanical 15 properties of the final dried coating as well as the opacity and surface gloss of the final coating. The additives also include pigment dispersants, thickeners and other rheology modifiers that provide suitable application and final coating properties. For architectural or house paints, the types of binders have changed significantly over the years. Paints of a century or more ago included 20 kalsomine or casein based binders as well as drying oil or bodied oil based binders. Developments from these oil based binders were oil modified resins, the best known being the alkyd class of binders. These alkyd binders require organic solvents, such as mineral spirits, to reduce the viscosity of the paints formed with such binders for application of the paint by brush or other means. 25 Over the last fifty years or so, as a result of environmental concerns associated with the evaporation of organic solvents, aqueous based coating compositions have been developed. These have been extensively adapted and now the vast majority of paint compositions are produced using water based latex polymers as binders. These polymeric latex binders form a water insoluble, durable film 30 by evaporation of water and the coalescence of the polymer particles. Typically the particles consist of (meth)acrylic copolymers or vinyl acetate copolymers. The early casein based coatings, mentioned above, suffered from WO 2005/092990 PCT/AU2005/000448 -2 the problem that they did not exhibit good exterior weather resistance and were largely limited to indoor, interior applications. Hydraulic cement based coating compositions have been developed over the last decades, and more recently products such as "THE PAINT" from 5 Ability Building Chemicals have provided architects and tradespeople with durable water based coatings based on Portland cement. These products are sold as a dry mix which is combined with water shortly before application. After their addition to and mixing with the water, the viscosity is suitable for brush or roller application. Coating compositions based on this technology are 10 disclosed in WO 01/81481 Al. Sugar is a renewable raw material that is widely used in food products as an additive or sweetener. Sugar is produced on large scale fron1 sugar cane as well as sugar beet. At the present time, there is a world over supply of sugar from countries with suitable tropical growing regions such as Brazil, U.S.A. 15 and Australia. Accordingly, the world price for refined sugar is at low levels of less than A$200 per tonne, and alternative, non-food, uses for sugar are eagerly sought. Ethanol production is one possibility which has been developed in some countries. However, this fuel use is constrained by the cost of petroleum derived fuels which, once taxes and excise duties are removed, are quite low. 20 Use of ethanol in petroleum based fuels usually requires government subsidies. There does not appear to be any suggestion in the technical literature that useful paint binders may be formed from the combination of a saccharide and a hydraulic cement. Indeed, in a paper "The Influence of Organic and Mineral Additives on Hydration of Cement", G. Vaickelionis, R. 25 Vaickelioniene, ISSN 1392-1320 Materials Science (Medziagotyra). Vol. 9, No. 3. 2003, it is stated that sugars in concentration as low as 0.03 to 0.15 wt % in cement will retard the setting and hardening times and reduce the strength of the cement. This is confirmed by the authors' conclusion in that paper that "sugars retard the hydration of Portland cement". 30 In the patent literature, there are some suggestions that useful compositions can be obtained by combining saccharides and cementitious type materials. However, most of these are confined to the effect of the saccharide WO 2005/092990 PCT/AU2005/000448 -3 as a retarder and the levels used are typically extremely low. These teachings are consistent with the technical literature. U.S. Patent No. 4,325,745 discloses paint repellent compositions that comprise a mixture of hydrocarbon oil, sodium chloride, sugar, aluminium 5 silicate, sand and acetic acid. These compositions are formulated to repel paint when applied to a substrate. The compositions of this citation have utility in spray booths where it is desired to stop paint adhering to parts of the booth. These compositions are far removed from the compositions of the present invention. 10 Japanese patent application JP 54-11 9529A (Nippon Hodo KK) (Derwent Abstract Accession No. 78303B/43) discloses fine aggregates of hydraulic slag where the slag is coated with one or more of a choice of ingredients, one of which may be sugar. The hydraulic slag, for example, blast furnace slag, is not normally regarded as a hydraulic cement and is rather a 15 pozzolan which is regarded as not a hydraulic cement. Japanese patent application JP 10-0 17864 A (Fujisawa Pharmacent Co Ltd) discloses compositions having 100-300kgs of cement, 0.5-10% of a retarder which can include as an example of a retarder sugar. The composition also includes a cement hardening accelerator at a level of 0.5-5% w/w of 20 hydraulic cement. The compositions are intended for use as soil improvement ingredients. I believe this citation is clearly distinguishable. The function of the sugar is simply as a retarder and also the levels that are used are reasonably low. The compositions of this citation also involve mixing the cement, retarder and its hardening accelerator with a large quantity of clay. 25 Japanese patent application JP 08-169742 A (Mutsuo Koji) discloses a hydraulic composition that does not cause efflorescence. It is also designed to provide salinity tolerance. The composition is a mixture of hydraulic cement and an additional component which can be selected from milk casein, alburnen, soya bean milk, starch solution and a starch sugar, nitrocellulose, soluble 30 viscose, agar solution. While no level of sugar is specified, it appears to be an incidental non-essential ingredient.

WO 2005/092990 PCT/AU2005/000448 -4 Japanese patent application JP 03-159944 (Fujita Corp) discloses hydraulic cementitious compounds where: they wish to retard the rate of setting to enable extended workability of the corrapositions. Commercial granular sugar is incorporated as a retarding agent. The use of sugar as a retarding agent 5 is consistent with the prior art. Japanese patent application JP 11-061126 A (Chicibu Onoda Cement Corp) relates to a cement grouting material which has increased workability. The composition includes a hydration inhibitor selected from a number of ingredients such as fluorides, phosphate salts, borate salts, oxycarboxylate 10 salts, dicarboxylic acids, ketocarboxylic a-cids, sugar alcohols and saccharides. The level of the hydration inhibitor is reasonably low, being in the range 0.05 1Owt%. The function of the sugar is that of a hydration inhibitor and its function is essentially as a set time retarder. United Kingdom patent GB 113,7285 A (Borch) discloses the very small 15 addition of cane sugar. Borch disclose that typically the addition of one quarter of one percent to Portland cement will adversely affect the strength of concrete formed from that cement. The citation states that the sugar prevents the Portland cement from setting normally and destroys its hydraulic effect. Again the purpose of the addition of the sugar tc> these hydraulic compositions 20 appears to be to simply retard the rate of cure to allow extended working times for the compositions. United Kingdom patent GB 357, 119A (Reard) is a relatively old British patent from 1930. The compositions of this citation include cement, lime, sugar, and soap. At page 2 lines 2D to 24, the inventor describes an 25 entirely new unexpected cooperative effect between the various ingredients. A typical composition is hydraulic cement, preferably white Portland (50 parts), hydrated lime (50 parts), sodium chloride (7 parts), calcium stearate (3 parts), and ordinary cane sugar (2 parts). The sugar is an optional ingredient and, as explained on page 2 lines 97 to 104, wher1 the sugar is used it affects the 30 rheology and enables the paint to spread out more evenly. It also has what is described as a remarkable cooperative effect when used with the salt and the WO 2005/092990 PCT/AU2005/000448 -5 stearate. The invention of this citation requires the essential presence of salt and stearates together with the sugar when sugar is used. United Kingdom patent GB 1,068,886 A (Martin-Marietta Corporation) teaches that it is known in this art field that simple sugars such as 5 glucose (dextrose), maltose, sucrose, fructose, etc., may be used to improve the strength of concrete when used at very low levels. However, as they are powerful retarders of cement hydration, the use has been limited. This citation is concerned with hydraulic cement additives which, unlike the simple sugars, do not severely retard or inhibit the hydration or hardening of the cement 10 compositions. The invention of this citation requires the use of saccharide polymers having a size from 3 glucose to 25 glucose units. The percentage of this saccharide polymer is quite low and is preferably used as a percentage by weight of cement of 0.01 to 0.50 percent. United Kingdom patent GB 1,508 761 A (Kao Soap Company 15 Limited) requires the use of modified oligosaccharides. The average molecular weight of the oligosaccharide is from 300 to 3500, and the modification to the oligosaccharide is that the terminal aldehyde group is converted to a carboxyl group. In the compositions of this citation, the level of this additive is extremely low, and is limited in claim 1 to 0.01 to 0.3 percent based on the 20 weight of the hydraulic cement. U.S. patent 4,095,987 (Walker) relates to an additive used to control the setting time for mortars used in cementing oil wells. The compositions are clearly not coatings. The weight percent of the additive is from 0.5 to 5 percent, and more preferably 0.5 to 2 percent by weight. The saccharides of 25 this invention has 82 percent by weight with chain length above a hexasaccharide structure. U.S. patent 4,210,456 (Miller) relates to cement rendering mortar compositions where an additive is used. The additive functions as a retarder and it enables air entrapment to take place. The air entrapment affects the 30 rheology of the render composition. The additive has from 3 to 25 glucose units. The additive is used at a very low level, with the maximum level being approximately 1 percent by weight.

17/10/05,atAustralian Oxides PCT speci,6 i L A 'U . -6 U.S. patent 5,221,343 (Graeur et al) relates to the use of a glucoside surfactant as an air entrapping admixture. Glucoside surfactants are quite distinct from saccharides. German patent DE 10052928 A (Keimfarben GmbH & Co KG (DE) 5 discloses compositions that combine monosaccharides and lime. No other hydraulic cements are used. United Kingdom patent 1,504,495 A (Kao Soap Company Limited) is similar to their other patent application (GB 1,508,761) discussed above. The modified oligosaccharides appear to be similar in both citations and have the 10 terminal carbonyl group converted to a carboxyl group. Again, the percentage of this additive is quite small. Japanese patent application JP 58-110482 (Shin Etsu Kasei KK) (Derwent Abstract Accession No. 83-731622/32) relates to a waterproofing agent for treating the surfaces of concrete. The compositions include a mixture 15 of hydraulic cement, a powder of siliceous materials, sodium carbonate and a retarder. The retarder is present at a percentage of 0.1 to 3 parts by weight. The retarder is selected from sugar, sodium, lignin sulfonate and carboxymethyl cellulose. Whilst the compositions of this citation are used as a coating, their use of sugar as a retarder is only in accordance with 20 acknowledged prior art. W096/39367 discloses coating and rendering compositions. In particular, Example 2 discloses a paste for the protection of rocks against crumbling. No pozzolanic material is present in this formulation and the formulation appears to perform satisfactorily for this very specific application. 25 It would be desirable to find alternative non-food applications for sugar and related renewable raw materials, and it would be desirable to have coating compositions that included such materials. Summary of the Invention 30 This invention provides in one form a coating composition which has a binder composition comprising a pozzolan and: Amended Sheet -~ A ' A T T -7 hydraulic cement 40 - 90% w/w saccharide 2 - 60% w/w casein 0 - 30% w/w alkalai silicate 0 - 10% w/w 5 Preferably, the hydraulic cement is ordinary Portland cement. Preferably, the binder further comprises hydrated lime. Preferably, the saccharide is present at least 5% w/w of the binder. Preferably, the saccharide is present at 10 - 60% w/w of the binder. 10 Preferably, the weight ratio of hydrated lime to ordinary Portland cement is in the weight ratio of 10:1 to 1:1. Preferably, the binder further comprises egg albumin. Preferably, the binder further comprises an alkalai silicate. Preferably, the saccharide is a sugar, more preferably a disaccharide 15 and most preferably sucrose. Preferably, the coating composition further comprises a pozzolan. The invention also provides a method of preparing a coating composition comprising the steps of preparing a dry mix of: hydraulic cement 40 - 90% w/w 20 saccharide 2 - 60% w/w casein 0 - 30% w/w alkalai silicate 0 - 10% w/w Detailed Description of the Invention 25 In this specification, a well known definition of sugar is adopted. This is from Hawley's Condensed Chemical Dictionary: "A carbohydrate product of photosynthesis comprised of one, two, or more saccharose groups. The monosaccharide sugars (often called simple sugars) are composed of chains of 2-7 carbon atoms. One of the carbons 30 carries aldehydic or ketonic oxygen, which may be combined in acetal or ketal forms. The remaining carbons usually have hydrogen atoms and hyroxyl groups. Chief among the monosaccharides are glucose (dextrose) and fructose Amended Sheet

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-8 (levulose). Among the disaccharides are sucrose (cane or beet sugar); lactose, found in milk; maltose, obtained by hydrolysis of starch; and cellobiose from partial hydrolysis of cellulose. High-polymer sugars occur as water-soluble gums such as arabic, tragacanth, etc." 5 The term "saccharide" used in this specification means a carbohydrate product having one, two or more saccharose groups. The term "hydraulic cement" used in this specification is also a standard definition, and from this same Dictionary is defined as: "Any mixture of fine-ground lime, alumina, and silica that will set to a 10 hard product by admixture of water which combines chemically with other ingredients to form a hydrate." In this specification, the term "casein" is also used in its art recognised meaning a colloidal aggregate composed of several proteins together with phosphorus and calcium in milk where it occurs as a heterogeneous complex 15 called calcium caseinate. The term "pozzolan" is used to describe an amorphous siliceous or siliceous and aluminous material which by itself possesses little or no cementitious value but will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide and alkalis at ordinary 20 temperatures to form compounds possessing cementitious properties. Examples are fly ash (also referred to as Pulverized Fuel Ash (PFA) and Ground Granulated Blast Furnace Slag (GGBFS). One of the remarkable features of the composition of the present invention is that relatively large properties of saccharide may be used as a 25 component of the binder. For example, in some compositions, the majority of the binder, that is over 50% of the binder composition, may be sucrose. The binder may be combined with other art recognised coating additives and auxiliary agents in art recognised quantities. For example, white opacifying pigments such as titanium dioxide may be used as well as colouring 30 pigments such as iron oxide type pigments. Extenders and fillers may be also used to change paint properties including gloss levels. A preferred extender is mica. Amended Sheet

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17/10/05,atAustralian Oxides PCT speci,9 is. eeIVU Z1t LAUUVA -9 In conventional paints, the binder is an organic material which, in the absence of pigments or extenders, forms a dry film after evaporation of a carrier solvent. In such conventional paints, it is easy to distinguish the binder from the other paint components. However, in the present invention, where the 5 binder comprises inorganic and organic components, it is more difficult. In the present invention, the binder is regarded as those components of the paint that react or hydrate with the hydraulic cement. Binder components include hydraulic cement and saccharides. Pozzolans (if present) are also regarded as components of the binder. In the example provided below, the first seven 10 listed components of the dry mix constitute the binder. The paints in the present invention are prepared by the following general method. The dry ingredients are combined, dry blended and then combined with water shortly before the time for application. The particle size of the various ingredients are the same as those generally used in the paint 15 industry. The coating composition of the present invention may be gloss or matt or of a surface appearance between these, and may be pigmented or non pigmented. The invention will be further described by reference to the following 20 examples where preferred embodiments are described. In the examples the parts are parts by weight unless otherwise indicated. Example 1 This example describes the preparation of a pigmented low gloss 25 paint. Casein powder (Alacid 734) 5.400 Egg White Powder (Egg Albumin) 3.000 Portland Off White Cement 4.741 30 Sodium Silicate 0.720 Sucrose (finely divided) 40.503 Hydrated Lime 23.291 Amended Sheet

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17/10/05,atAustralian Oxides PCT speci10 - 10 Ground Granulated Blast Furnace Slag 3.723 Dispersant (Cosmotron@ DPV-CA ) 0.351 Microscopic Air Entraining Admixture (Maxim-Air +) 0.002 Stearic Acid Powder (Palmac** 70/18) 0.800 5 Drycryl DP2904 - Acrylic Powder ex Rhom & Haas 4.672 Titanium Dioxide RCL 595 (Millenium Chemicals Pty Ltd) 2.070 Mica (325 Mesh) 2.430 Defoaming Additive (Rhoximat+ 6352DD) 0.297 10 Iron Oxide Colouring Pigment (Abilox ) 8.000 100.000 15 *Sodium salt of naphthalene sulphonic acid condensates (BASF) ** Acidchem International Sdn. BHd. + Rhodia Ability Building Chemicals 20 A dry blend of the above ingredients was prepared by suitable milling. Three parts by volume of this dry mixture was added to one part of potable water while stirring. The mixture was allowed to stand for 10 minutes and then restirred for two minutes. The paint so formed was then applied to a sound clean substrate to form a wet film build of 200 pim. Although not essential, it 25 was found to be beneficial to lightly spray the coating with water after the film coating has initially set and over the next 48 hours. The paint film formed was found to be hard and water resistant and exhibited a good balance of mechanical properties such as marr and chip resistance. It was also possible to apply the coating compositions as trowelling 30 finishes. In this case, water soluble thickeners were found to be useful rather than simply reducing the content of water.

17/10/05,atAustralian Oxides PCT speci,II . -, I /IIU4UU )/UUU4Q6 Received 24 October 2005 - 11 Example 2 This example describes the preparation of a clear gloss paint. A clear coating/sealer was prepared according to the method of Example 1 but with the 5 following dry mix ingredients. Casein powder (Alacid 734) 9.000 Egg White Powder (Egg Albumin) 3.000 Portland Off White Cement 6.316 Sodium Silicate 0.720 10 Sucrose (finely divided) 30.105 Hydrated Lime 38.935 Ground Granulated Blast Furnace Slag 3.723 Air Entraining Admixture (Maxim-Air 0.001 Stearic Acid Powder (Palmac** 70/18) 0.800 15 Drycryl DP2904 - Acrylic Powder (Rhom & Haas) 4.670 Mica (325 Mesh) 2.430 Defoamning Additive (Rhoximat 6352DD) 0.300 When prepared and tested as a paint, as in Example 1, this 20 composition gave a hard resistant sealer coat to a masonary substrate. The mechanism by which such large amounts of saccharide may be incorporated as part of the binder are not known or fully understood. However, it is speculated that the hydroxyl groups on the saccharides may participate in the hydration reactions and/or form a saccharate compound by interaction with 25 the metallic oxide. However, the present invention is not limited to such an explanation. Since modifications within the spirit and scope of the invention may be readily effected by persons skilled in the art, it is to be understood that the invention is not limited to the particular embodiment described, by way of 30 example, hereinabove. For example, the dry film build of the coatings of the present invention are typically in the range 100 to 300 Rim. However, the compositions of the present invention may be used as renders and trowel Amended Sheet

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17/10/05,atAustralian Oxides PCT speci,12 Received 24 October 2005 - 12 applied hard plasters where the total thickness of the applied layers may be up to 10 or 20 mm. Indeed, as the curing mechanism is essentially a hydration reaction which does not involve the evaporation of water, even greater thickness may be used. A test block 100mm x 100mm x 100mm was cast 5 using a composition according to the invention and cured to a hard block after 24 hours. The composition may be used as replacements for plasterboard, fibrocement sheet and other building materials. Amended Sheet

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Claims (13)

1. A coating composition which has a binder composition comprising a pozzolan and: 5 hydraulic cement 40 - 90% w/w saccharide 2 - 60% w/w casein 0 - 30% w/w alkalai silicate 0 - 10% w/w. 10

2. A coating composition as defined in claim 1 wherein the hydraulic cement is ordinary Portland cement.

3. A coating composition as defined in claim 1 or claim 2 wherein the binder further comprises hydrated lime. 15

4. A coating composition as defined in any one of claims 1 to 3 wherein the saccharide is present at least 5% w/w of the binder.

5. A coating composition as defined in any one of claims 1 to 4 wherein 20 the saccharide is present at 10 - 60% w/w.

6. A coating composition as defined in any one of claims 3 to 5 wherein the weight ratio of hydrated lime to ordinary Portland cement is in the weight ratio of 10:1 to 1:1. 25

7. A coating composition as defined in any one of claims 1 to 6 wherein the binder further comprises egg albumin.

8. A coating composition as defined in any one of claims 1 to 7 wherein 30 the binder further comprises an alkalai silicate. Amended Sheet TDTP A /A TT L41,.ua.us.m . .IUcs r- - Received 24 uctooer zuv, - 14

9. A coating composition as defined in any one of claims 1 to 8 wherein the saccharide is a sugar.

10. A coating composition as defined in claim 9 wherein the saccharide is 5 a disaccharide.

11. A coating composition as defined in claim 10 wherein the saccharide is sucrose. 10

12. A method of preparing a coating composition comprising the steps of preparing a dry mix of a pozzolan and: hydraulic cement 40 - 90% w/w saccharide 2 - 60% w/w casein 0 - 30% w/w 15 alkalai silicate 0 - 10% w/w.

13. A method as defined in claim 12 wherein the saccharide is sugar and the sugar is present as a percentage of the binder. 20 Amended Sheet Tn7 A /A T T