Title of Invention

A FLYASH BASED COATING COMPOSITION AND A METHOD OF PREPARATION THEREOF

Abstract

This invention relates to a flyash based coating composition comprising flyash, polymeric waste, a vehicle and a binder, the said coating being prepared comprising adding flyash to the vehicle with stirring followed by addition of borax and calcium stearate with stirring to obtain a dispersion, dissolving polymeric waste (thermocol) and adding a binder (ISMAC-12k) with stirring followed by adding the dispersion thereto to obtain the flyash based coating.

Full Text

FIELD OF THE INVENTION This invention relates to a flyash based coating composition and a method of preparation thereof. This invention further relates to a flyash based coating to be used as an exterior coating, under coating far cars, anti-corrosive and fire-proof coating. BACKGROUND OF THE INVENTION Flyash is a part of coal combustion residue at thermal power plants. When powdered coal is burnt using fluidised bed combustor the carbon matters are nearly completely burnt out and residue which is mainly alumino siliceous in nature is left behind as the bottom ash. A part of the residue which is of very fine size is carried over by the flue gas and spewed in the atmosphere. These residues are called flyash. Flyash has two phases, the vitreous (60-85%) and crystal 1ine (15-40%) phase and is classified into two groups according to its Cao/Al 0 /SiO 2 3 2 content, the alumina-si 1iceous group (SiO , Al 0 ; Cao 2 2 3 2 2 3 Flyash has some degree of Pozsolanic property) ie. in presence of water? flyash sets into a hard cement itious material. This property is uti1ised for the development of flyash based coating. OBJECTS OF THE INVENTION It is an object of this invention to propose a flyash based coating which is essentially inert to acids and alkalis, and a 2 method for the preparation thereof. It is a further object of this invention to propose a flyash based coating which has good water-repellant and anti-corrosive properties. Another object of this invention is to propose a flyash based coating which is not flammable and has low thermal conductivity. Other objects and advantages of this invention will be more apparent from the ensuing description. Thus according to this invention is provided a flyash based coating composition comprising flyash, polymeric waste, a vehicle and a binder, such as herein described, in a proportion of 3 to 4 g of flyash, 10 to 15 ml of vehicle, 2 to 2.5 g of polymeric waste and 1 to 1.5 ml of binder. According to this invention is further provided a process for the preparation of flyash based coating composition comprising adding flyash to the vehicle with stirring followed by addition of borax and calcium stearate with stirring to obtain a dispersion; dissolving polymeric waste such as thermocol polystrene in a vehicle such as MIBK and adding the binder with stirring followed by adding the dispersion thereto to obtain the flyash based coating. In accordance with this invention, flyash which essentially consists of silica and alumina works as an inert filler. The cenospheres and plerospheres present in flyash impart low thermal conductivity and high tensile strength and the mullite present - 3. method for the preparation thereof. It is a further object of this invention to propose a flyash based coating which has good water-repe1lant and anti-corrosive properties. Another object of this invention is to propose a flyash based coating which is not flammable and has low thermal conductivity. Other objects and advantages of this invention will be more apparent from the ensuing description. Thus according to this invention is provided a flyash based coating composition comprising flyash, polymeric waste, a vehicle and a binder-According to this invention is further provided a process for the preparation of flyash based coating composition comprising adding flyash to the vehicle with stirring followed by addition of borax and calcium stearate with stirring to obtain a dispersions dissolving polymeric waste in the vehicle and adding the binder with stirring followed by adding the dispersion thereto to obtain the flyash based coating. In accordance with this invention, flyash which essentially consists of silica and alumina works as an inert filler- The cennspheres and pleraspheres present in flyash impart low thermal conductivity and high tensile strength and the mullite present 3 possibly adds to the inertness of the material. The flyash used has very fine size grains. Whole flyash is sieved using sieve of mesh size -300, only that fraction which passes throuhg the sieve is collected and used. The average size range of flyash used is 20-50 urn. Since a fraction of the flyash material is of very fine size, this forms a good emulsion with vehicles. The polymeric waste used is collected locally. It is readily available and can act as a good binder. It is essentially thermocol (polystyrene). The vehicle used is a polar compound which can solubilise the polymeric waste , such as for example , methyl isobutyl ketone (MIBK). The binder used is ISMAC-12K. The flyash used is mainly hydrophi1ic in nature and is therefore incompatible with lyophilie solvents/polymer matrix with hydrocarbon background. Therefore, to make it compatible with the polymeric matrix, BINDER-ISMAC-12K is used. The binder-code named ISMAC-12K is synthesised by adding an amine such as triethanolamine to an organic sulfonic acid such as lauryl sulfonic acid and mixing the same, followed by adding an organic acid such as acetic acid to maintain the pH and thereafter adding lime to optimise the pH. Fire-proofing chemicals may be added to improve the fire-proofing capacity of the composition. In accordance with this invention, the process of preparing the flyash based coating composition comprises adding about 3 to 4g 4 of flyash slowly to MIRK, over a period of time and adding finely dispersed borax and calcium stearate with stirring to form a dispersion. About 2 to 2"5g of polymeric waste is dissolved in MIBK and the mixture is thoroughly agitated) fallowed by adding about 1 to 1.5ml ISMAC-12K thereto with constant stirring for hamagenisation of the mixture. This mixture is then slowly added to the dispersion with stirring. The total solvent used for dissolving flyash and the polymeric waste is about 10 to 15ml and the total time of stirring is 0.5 to 1 hr and the time of addition is 0.2 to 0.5 hr. The invention will now be explained in greater detail with the help of the following non-limiting example. EXAMPLE Preparation of flyash based coating A. 1kg. of flyash was added slowly to 2L of MIBK maintaining a constant rate of stirring. The homogenised dispersion was made over a period of one (lh) hour. Finely dispersed borax (100g) calcium stearate stirred for further half an hour. A consistent dispersion is formed at this stage. B. 1kg. of polymeric waste Cthermocol) was dissolved in 4L of MIBK and thoroughly agitaged for 1/2 hr.. To this, 100g of ISM- Ac-12 was added slowly wh i le maintaining a thorough and constant stirring. The whole mixture was homogenised using a thorough 5 stirring for 1/2 hr.. C. A and E were mixed together by slowly combining A & B together while maintaining a thorough stirring. Care should be taken at this stage to check excessive foam formation. The whole combination of A & B took 2 hrs. for a complete stirring. Preparation of binder (ISMAC-12K) One mole of lauryl sulfonic acid (266g) was weighed and taken in a polyethylene beaker (3D. Triethanolamine (1 mole, 117g) was added slowly maintaining a constant stirring with a mechanical/ electric stirrer at a speed of 60 rpm. After the mixing was over, the pH of the finished material was checked. A little (15ml) of acetic acid was added to bring the pH to 7.0, 10gms of fine lime CaO (anhydrous) (sieved through mesh of -400) was slowly added and the whole mixture was obtained. The final pH should be 8.0-8.5. The coating thus obtained is then subjected to various tests to ascertain its properties. It is found to be water repellant and the wetted material is found to harden with time to form a tough film. The coated panels were found to have a good anti-corrosive property and are resistant to flame and strong acids. The coating is not soluble in common organic solvents. Test for water repellancy Water repellancy test was performed by dipping a plate coated 6 with the flyash based coating 1L water for 3 hrs.. The material was taken out and shaken. No appreciable wetting was observed-Test for hardening with 1ime The wetted material hardens with time to form a very tough film while the initial coat could be scratched with a sharp iron nail) it becomes extremely difficult to scratch after one year- Tests for anti-rusting properties Coated panels were kept immersed in water' for 5 days. The following observations were made : Rusting some spots No rusting No rusting No rusting Table 1. Composition A (Flyash:Thermocol 1:2) 2. Composition B (Flyash=Thermocol 1 :3) 3. Composition C (Flyash:Thermocol 1:4) 4. Composition D (Flyash :Thermocol 1:5) Drying time The drying time required for the coating formulations were about 0.25-0.5 h. This is because the volatile component had a boiling range of 115-120 C. The average drying time, hardening time, etc. as compared with a standard paint "X" is given below : Table 1: Drying time and hardening time Paint X Entry 1. Drying Time 0.5 h Hardening Time 24 hr Drying Time Hardening Time 7 ?Drying time is considered on the time at which the painted surface is not smeared on touching the surface Entry 1: Flyash coating containing 1:2:8 of flyash:Polymeric: MIBK Entry 2 : Flyash coating containing 2:2:8 of flyash:Polymeric: MIBK Entry 3 : Flyash coating containing 3:2:8 of flyash:Polymeric: MIBK Entry 4 : Flyash coating containing 4 : 2 = 8 of flyash : Polymeric: MIBK Entry 5 : Flyash coating containing 5 : 2 : 8 of flyash : Polymeric : MIBK 8 SOLUBILITY TEST : To check the solubility of the coatings, chloroform/carbon tetrachloride/MIBK were applied on the coated surface. It was observed that once the coatings were hardened the solvent could not effectively remove the coatings easily. FLAME TEST: Flame test was performed on the coatings by placing the coated panels on to gas burners. The following observations were made Flyash based coatings EFFECT OF STRONG ACIDS ON FLYASH BASED COATING: For testing the effect of strong acids on the flyash based coating the following experiments were performed. 1. Plates measuring 4.5cm x 2 cm were coated with flyash based coatings on one side. 2. Different size fraction (size ranges 30 - 300 µm) of flyash were used. 3. Alt the coatings prepared contained same concentration of flyash and polymeric waste. The amount of binder and solvent used also remained constant in all the preparations. 8 4. To each plate at located sites, one drop of concentrated acid was added and allowed to react over a period of 24 hours (under cover). 5. Sulphuric and nitric acids were used for testing purpose. 6. For each acid three different concentrations were used namely 1N, 8N, 16 N. 7. After 24 hours the plates were thoroughly washed with water. 8. The plates were dried at 100-120°C for 6 hours. 9. The difference between initial and final weights of the plate gave an estimate of loss of material. 10. Scanning electron microscopic studies of the plates (after acid treatment) were carried out. RESULTS Scanning electron microphotography reveals the following : 1. Flyash based coatings containing coarser particles were more easily attacked as compared with that of fine particles. 10 Table : Morphological Analysis of Acid Treated Flyash Based Coatings 11- -11 WE CLAIM 1. A flyash based coating composition comprising flyash, polymeric waste, a vehicle and a binder such as herein described, in a proportion of 3 to 4 g of flyash, 10 to 15 ml of vehicle, 2 to 2.5 g of polymeric waste and 1 to 1.5 ml of binder. 2. The composition as claimed in claim 1, wherein said polymeric waste is a compound, such as, for e.g. thermocol (polystyrene). 3. The composition as claimed in claim 1, wherein said vehicle is a solvent, such as, for e.g. methyl isobutyl ketone (MIBK). 4. The composition as claimed in claim 1, wherein said binder is a compound, such as ISMAC-12K. 5. The composition as claimed in claim 1, wherein the flyash used has an average size in the range of 20-25 µm. 6. A process for the preparation of a flyash based coating composition comprising adding flyash to the vehicle with stirring followed by addition of borax and calcium stearate with stirring to obtain a dispersion, dissolving polymeric waste such as thermocol (polystrene) in a vehicle such as MIBK and adding the binder with stirring followed by adding the dispersion thereto obtain the flyash based coating composition. 1. -12- 7. The process as claimed in claim 6, wherein 3 to 4g of said flyash is added. 8. The process as claimed in claim 6, wherein 2 to 2.5 g of said polymeric waste is added. 9. The process as claimed in claim 6, wherein the total quantity of vehicle used is 10 to 15 ml. 10.The process as claimed in claim 6, wherein 1 to 1.5 ml of binder is added. 11.The process as claimed in claim 6, wherein said polymeric waste is a compound, such as, for e.g. Thermocol (polystyrene). 12.The process as claimed in claim 6, wherein said vehicle is a solvent, such as, for e.g. Methyl isobutyl ketone (MIBK). 13.The process as claimed in claim 6, wherein said binder is a compound, such as ISMAC-12K. 14.The process as claimed in claim 6, wherein the flyash used has an average size in the range of 20-50 µm. 15.The process as claimed in claim 6, wherein the total time of stirring is 0.5 hr. to 1 hr. -13- 16.The process as claimed in claim 6, wherein the total time of addition is 0.2 hr. to 0.5 1 hr. 17. A flyash based coating composition substantially as herein described and illustrated. 18.A process for the preparation of a flyash based coating composition substantially as herein described and illustrated. ith Dated this 10th day of February 2003. This invention relates to a flyash based coating composition comprising flyash, polymeric waste, a vehicle and a binder, the said coating being prepared comprising adding flyash to the vehicle with stirring followed by addition of borax and calcium stearate with stirring to obtain a dispersion, dissolving polymeric waste (thermocol) and adding a binder (ISMAC-12k) with stirring followed by adding the dispersion thereto to obtain the flyash based coating.

Documents:

00630-cal-2001-abstract.pdf

00630-cal-2001-claims.pdf

00630-cal-2001-correspondence.pdf

00630-cal-2001-description(complete).pdf

00630-cal-2001-description(provisional).pdf

00630-cal-2001-form-1.pdf

00630-cal-2001-form-18.pdf

00630-cal-2001-form-2.pdf

00630-cal-2001-form-26.pdf

00630-cal-2001-form-3.pdf

00630-cal-2001-form-5.pdf

00630-cal-2001-latters patent.pdf

00630-cal-2001-reply f.e.r.pdf

630-cal-2001-granted-abstract.pdf

630-cal-2001-granted-claims.pdf

630-cal-2001-granted-description (complete).pdf

630-cal-2001-granted-form 2.pdf

630-cal-2001-granted-specification.pdf