Claims:WE CLAIM:
1. A coating composition comprising:
(i) 5 wt% to 40 wt% of a stabilized slaked lime with respect to the total amount of the coating composition;
(ii) 10 wt% to 50 wt% of a binder with respect to the total amount of the coating composition;
(iii) 40 wt% to 50 wt% of an extender with respect to the total amount of the coating composition;
(iv) 1 wt% to 5 wt% of at least one additive with respect to the total amount of the coating composition; and
(v) qs water.
2. The coating composition as claimed in claim 1, wherein said stabilized slaked lime comprises:
(a) 30 wt% to 50 wt% of solid lime;
(b) at least one poly-carboxylate in the range of 4 to 9 % with respect to the total weight of solid lime;
(c) at least one carbohydrate in the range of 0.1 to 3.0 % with respect to the total weight of solid lime; and
(d) at least one oil derivative in the range of 0.1 to 10 % with respect to the total weight of solid lime.
3. The coating composition as claimed in claim 2, wherein said poly-carboxylate is sodium salt of poly-carboxylic acid;
wherein said poly-carboxylic acid is at least one selected from acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, mesaconic acid, fumaric acid, citraconic acid, vinyl acetic acid, acryloxy propionic acid.
4. The coating composition as claimed in claim 2, wherein said carbohydrate is at least one selected from raw starch, modified starch, oxidized starch, esterified starch, etherified starch, cationated starch, crosslinked starch, a-starch, hydroxypropyl starch and gelatinized starch;
wherein, raw starch is selected from nard starch, potato starch, Japanese potato starch, tapioca starch, cone starch, wheat starch and rice starch; and modified starch is selected from dextrin, baked dextrin, enzyme-modified dextrin, cyclodextrin and dialdehyde starch.
5. The coating composition as claimed in claim 2, wherein said oil derivative is at least one selected from salts of fatty acid, plant and mineral oils, low molecular weight silanes and siloxanes.
6. The coating composition as claimed in claim 5, wherein said oil derivative is potassium oleate.
7. The coating composition as claimed in claim 1, wherein said binder is at least one selected from alkyds, acrylics, vinyl-acrylics, vinylacetate/ethylene (VAE), polyurethanes, polyesters, melamine resins, epoxy, high molecular weight silanes or siloxanes or oils;
8. The coating composition as claimed in claim 7, wherein said binder is styrenated butyl acrylate.
9. The coating composition as claimed in claim 2, wherein said extender is at least one selected from calcium carbonate, talc, clays, dolomite, silica and silicates.
10. The coating composition as claimed in claim 1, wherein said additive is at least one selected from thickener, plasticizer, coaleasing agent and wetting agent.
11. The coating composition as claimed in claim 10, wherein said thickener is hydroxyethyl Cellulose, said plasticizer is triethylene Glycol, said coaleasing agent is isobutyrate of molar mass 216 g/mol and said wetting agent is Soya Lecithin.
12. The coating composition as claimed in claim 1 being characterized by having
• a wet shelf-life of at least 2 years;
• VOC of less than 10 gm/lit;
• SD value of less than 0.01 m;
• an anti-bacterial performance with more than 99% kill; and
• flame retardant property.
13. A process for preparing the stabilized slaked lime as claimed in claim 2, said process comprising the following steps:
i. roasting limestone at a temperature in the range of 900 °C to 1200 °C for a time period in the range of 6 to 72 hours to obtain a roasted lime;
ii. slaking said roasted lime with water in a predetermined ratio for at least 2 days followed by filtering to obtain a matured slaked lime;
iii. adding a mixture of predetermined amounts of at least one poly-carboxylate, at least one carbohydrate and at least one oil derivative to said matured slaked lime at a temperature in the range of 20 °C to 40 °C to obtain a mass; and
iv. stabilizing said mass for a time period in the range of 24 to 48 hours followed by filtering to obtain said stabilized slaked lime.
14. The process as claimed in claim 13, wherein said predetermined ratio of said roasted lime to water is in the range of 1:3 to 1:6.
15. The process as claimed in claim 13, wherein said predetermined amounts of said poly-carboxylate is in the range of 4 to 9 % with respect to the total weight of solid lime; said carbohydrate is in the range of 0.1 to 3.0 % of the total weight with respect to the solid lime; and said oil derivative is in the range of 0.1 to 10% with respect to the total weight of the solid lime.
Dated this 08th day of January 2021

MOHAN RAJKUMAR DEWAN
IN/PA-25
OF R. K. DEWAN & CO.
APPLICANT’S PATENT ATTORNEY

TO,
THE CONTROLLER OF PATENTS,
THE PATENT OFFICE
AT MUMBAI
, Description:FIELD
The present disclosure relates to a coating composition and a process for its preparation.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used to indicate otherwise.
Hydraulicity refers to a property of a binder to harden in contact with water. Hydraulicity is produced by burning a limestone containing silica, alumina and iron oxides which above certain temperatures combine, totally or partially, with the Calcium Oxide.
SD value refers to steam diffusion or air layer equivalence. It is a measure of how much of a barrier a paint coating is to water vapour and how easily the vapour can pass through this barrier, it is measured in meters. The lower SD Value indicates that more moisture is able to pass through the barrier and the higher SD Value indicates that lower moisture is transfered through the barrier.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
Water-based paint composition requires lime of a specific quality when used in the composition. Unless this specific quality is achieved, the coating containing lime exhibits undesired consistency, improper finish with grits and low shelf-life. To overcome these issues, the hydraulicity of lime needs to be reduced to less than 0.01. To achieve this property of hydraulicity, lime needs to be matured. Maturing the lime refers to a step of allowing the slaked lime slurry to condense to a smooth form and subsequent removal of hydraulic components by filtration. Further, this lime slurry needs to be efficiently transported through existing systems like other slurries. Such matured lime slurries exhibit high tendency of lump formation accompanied by hard settling. Due to this the handling and transportation of lime slurries become a challenge. This limits the use of lime in the paint and coating industry.
Therefore, there is felt a need for preparing a stabilized slaked lime that can be used in the coating composition and thus mitigating the aforestated drawbacks.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
It is an object of the present disclosure to ameliorate one or more problems of the prior art or to at least provide a useful alternative.
Another object of the present disclosure is to provide a coating composition.
Still another object of the present disclosure is to provide a stabilized coating composition that exhibits high breathability along with anti-bacterial and flame retardant property.
Yet another object of the present disclosure is to provide a process for preparation of the coating composition.
Still another object of the present disclosure is to provide a process for preparation of the coating composition by using a stabilized slaked lime.
Another object of the present disclosure is to provide a stabilized slaked lime.
Yet another object of the present disclosure is to provide a process for preparation of the stabilized slaked lime.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a water based coating composition comprising 5 wt% to 40 wt% of stabilized slaked lime with respect to the total amount of the coating composition, 10 wt% to 50 wt% of a binder with respect to the total amount of the coating composition, 40 wt% to 50 wt% of an extender with respect to the total amount of the coating composition, 1 wt% to 5 wt% of at least one additive with respect to the total amount of the coating composition and qs water.
The present disclosure further relates to a process for preparing the stabilized slaked lime. The process comprises the step of roasting limestone at a temperature in the range of 900 °C to 1200 °C for a time period in the range of 6 to 72 hours to obtain a roasted lime. The roasted lime is slaked in water in a predetermined ratio for at least 2 days followed by filtering to obtain a matured slaked lime. A mixture of predetermined amounts of at least one poly-carboxylate, at least one carbohydrate and at least one oil derivative are added to the matured slaked lime at a temperature in the range of 20 °C to 40 °C to obtain a mass. The mass is stabilized for a time period in the range of 24 to 48 hours followed by filtering to obtain the stabilized slaked lime.
DETAILED DESCRIPTION
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components, and methods, to provide a complete understanding of embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used, in the present disclosure, is only for the purpose of explaining a particular embodiment and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well, unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having,” are open ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
Water-based paint composition requires lime of a specific quality when used in the coating composition. Unless this specific quality is achieved, the coating containing lime exhibits undesired consistency, improper finish with grits and low shelf-life. To overcome these issues, the hydraulicity of lime needs to be reduced to less than 0.01. To achieve this property of hydraulicity, lime needs to be matured. Maturing the lime refers to a step of allowing the slaked lime slurry to condense to a smooth form and subsequent removal of hydraulic components by filtration. Further, this lime slurry needs to be efficiently transported through existing systems like other slurries. Such matured lime slurries exhibit high tendency of lump formation accompanied by hard settling. Due to this the handling and transportation of lime slurries become a challenge. This limits the use of lime in the paint and coating industry.
The present disclosure therefore, provides a stabilized slaked lime that can be used in coating compositions and thus the coating composition exhibits high breathability along with antibacterial performance and flame retardant property.
In a first aspect, the present disclosure provides a coating composition comprising 5 wt% to 40 wt% of stabilized slaked lime with respect to the total amount of the coating composition, 10 wt% to 50 wt% of a binder with respect to the total amount of the coating composition, 40 wt% to 50 wt% of an extender with respect to the total amount of the coating composition, 1 wt% to 5 wt% of at least one additive with respect to the total amount of the coating composition; and qs water.
In the coating composition of the present disclosure, the optimized amount of stabilized slaked lime is used so as to provide desired whiteness and opacity to the coating composition along with anti-microbial and flame retardant properties. The use of an optimized amount of stabilized slaked lime can be used as a pigment, as well as a binder in the coating composition. Thus, the slaked lime acting as the pigment provides desired whiteness and opacity to the coating composition. Further, the use of the optimized amount of stabilized slaked lime in the coating composition maintains the alkaline pH of the coating composition that results in anti-microbial property to the coating.
It is observed that when excess of slaked lime is used with other ingredients constant, the whiteness and opacity increases with the increase in the chalking tendency which are undesirable property of the coating. In case of decrease in the quantity of slaked lime, the coating will exhibit lower whiteness and opacity.
The stabilized slaked lime comprises 30 wt% to 50 wt% of solid lime, at least one poly-carboxylate in the range of 4 to 9 % of the weight of lime, at least one carbohydrate in the range of 0.1 to 3.0 % of the weight of lime and at least one oil derivative in the range of 0.1 to 10% of the weight of lime.
In an exemplary embodiment of the present disclosure, the stabilized slaked lime comprises 35 wt% of a solid lime, at least one poly-carboxylate in the range of 5 % with respect to the weight of the solid lime, at least one carbohydrate in the range of 0.5% with respect to the weight of the solid lime and at least one oil derivative in the range of 0.3% with respect to the weight of the solid lime.
In accordance with an embodiment of the present disclosure, the poly-carboxylate is sodium salt of poly-carboxylic acid. The poly-carboxylic acid is at least one selected from acrylic acid, methacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, mesaconic acid, fumaric acid, citraconic acid, vinyl acetic acid, acryloxy propionic acid.
In accordance with an embodiment of the present disclosure, the carbohydrate is at least one selected from raw starch, modified starch, oxidized starch, esterified starch, etherified starch, cationated starch, crosslinked starch, a-starch, hydroxypropyl starch and gelatinized starch. The raw starch is selected from nard starch, potato starch, Japanese potato starch, tapioca starch, corn starch, wheat starch and rice starch and the modified starch is selected from dextrin, baked dextrin, enzyme-modified dextrin, cyclodextrin and dialdehyde starch. In an exemplary embodiment of the present disclosure, the carbohydrate is dextrin starch.
The oil derivative is based on poly(alkoxy ester) and fatty esters. In accordance with an embodiment of the present disclosure, the oil derivative is at least one selected from salts of fatty acids including stearates and oleates, plant and mineral oils, silanes and siloxanes. In an embodiment of the present disclosure, the oil derivative is potassium oleate (salts of fatty acid).
The binder is at least one selected from alkyds, acrylics, vinyl-acrylics, vinyl acetate/ethylene (VAE), polyurethanes, polyesters, melamine resins, epoxy, silanes or siloxanes or oils. In an embodiment of the present disclosure, the binder is styrenated butyl acrylate (vinyl-acrylics).
The extender is at least one selected from calcium carbonate, talc, clays, dolomite, silica and silicates. In an exemplary embodiment of the present disclosure, the extender is a mixture of calcium carbonate and clays.
The additive is at least one selected from thickener, plasticizer, coaleasing agent and wetting agent. In an exemplary embodiment of the present disclosure, the thickener is hydroxyethyl cellulose, the plasticizer is triethylene glycol, the coaleasing agent is isobutyrate (having molar mass 216 g/mol) and the wetting agent is soya lecithin.
The coating composition of the present disclosure is characterized by having a wet shelf-life of at least 2 years, VOC of less than 10 gm/lit, SD value of less than 0.01 m, an anti-bacterial performance with more than 99% kill and flame retardant property having 0% smoke density.
In a second aspect, the present disclosure provides a process for preparing the stabilized slaked lime.
The process comprises the step of roasting limestone at a temperature in the range of 900 °C to 1200 °C for a time period in the range of 6 to 72 hours to obtain a roasted lime.
The roasted lime is slaked in water in a predetermined ratio for at least 2 days followed by filtering to obtain a matured slaked lime.
In accordance with the present disclosure, the roasted lime is slaked in water for a time period in the range of 2 days to 365 days. In an embodiment of the present disclosure, the roasted lime is slaked in water for a time period in the range of 2 days to 45 days. In an exemplary embodiment of the present disclosure, the roasted lime is slaked in water for 24 days.
In an embodiment of the present disclosure, the predetermined ratio of the roasted lime to water is in the range of 1:3 to 1:6. In an exemplary embodiment of the present disclosure, the predetermined ratio of the roasted lime to the water is 1:3.
A mixture of predetermined amounts of at least one poly-carboxylate, at least one carbohydrate and at least one oil derivative is added to the matured slaked lime at a temperature in the range of 20 °C to 40 °C to obtain a mass.
In an embodiment of the present disclosure, the predetermined amounts of the poly-carboxylate is in the range of 4 to 9 % with respect to the weight of the solidlime; the carbohydrate is in the range of 0.1 to 3.0 % with respect to the weight of the solid lime; and the oil derivative is in the range of 0.1 to 10% with respect to the weight of the solid lime.
The mass is stabilized for a time period in the range of 24 to 48 hours followed by filtering to obtain the stabilized slaked lime.
Stabilization of a slaked lime is carried out to attain a quality suitable for its use in paint and coatings. The stabilized slaked lime prepared by the process of the present disclosure is easy to handle and does not exhibits lump forming and hard settling tendencies. The stabilized slaked lime in the coating composition of the present disclosure offers a stable consistency, a finish without grits and desirable wet shelf-life to the coating composition.
The coating composition of the present disclosure exhibits high breathability along with anti-bacterial and flame retardant property due to the presence of matured slaked lime in the coating composition.
The coating composition of the present disclosure can be used as interior decorative coating.
The foregoing description of the embodiments has been provided for purposes of illustration and not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment, but, are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purpose only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS
Experiment 1: Preparation of the stabilized slaked lime
1000 g of limestone was roasted at 950°C for 8 hours to obtain a roasted lime. The roasted lime was slaked in water in a ratio of 1:3 at 30°C for 24 days to obtain a matured slaked lime. A mixture containing 50g of Sodium Polycarboxylate (poly-carboxylate), 5g of dextrin starch (carbohydrate) and 40g of potassium oleate (oil derivative) was added to the matured slaked lime at 30 °C to obtain a mass. The mass was stirred (stabilized) for 24 hours at 30 °C followed by filtering to obtain the stabilized slaked lime slurry.
Experiment 2: Preparation of the coating composition
Example 1: Preparation of the coating composition comprising 35 wt% of the stabilized slaked lime slurry
350 g of the stabilized slaked lime slurry prepared in experiment 1 was mixed with 100 g of styrenated butyl acrylate (binder), 365 g of mixture of talc, calcium carbonate and calcined clay (extender) and 2.5 g of hydroxyethyl Cellulose (thickner), 12 g of triethylene glycol (plastisizer) and about 50 gm of other paint additives (wetting agent- soya lecithin and coaleasing agent- isobutyrate of molar mass 216 g/mol) in 118 g of water to obtain a mixture. The mixture was stirred at 30°C for 6 hours to obtain the coating composition.
Example 2: Preparation of the coating composition comprising 10 wt% of the stabilized slaked lime slurry
100 g of the stabilized slaked lime slurry prepared in experiment 1 was mixed with 200 g of styrenated butyl acrylate (binder), 400 g of mixture of Talc, calcium Carbonate and Calcined Clay (extender) and 5 g of hydroxyethyl Cellulose (thickner), 12 g of triethylene Glycol (plastisizer) and about 50 gm of other paint additives (wetting agent- soya lecithin and coaleasing agent- isobutyrate of molar mass 216 g/mol) in 233 g of water to obtain a mixture. The mixture was stirred at 30°C for 6 hours to obtain the coating composition.
Comparative Example: Preparation of the coating composition comprising lime (unstabilized)
The experimental procedure was same as in Example 1 except 11.5 g of lime was used instead of stabilized slaked lime slurry in the coating composition.
It was observed that when the coating composition was prepared with lime (unstabilized) at 6 wt%, it exhibited high viscosity pick-up during processing and formation of grits occurred after 30 days of storage. Further, the wet shelf life of the coating composition prepared with lime (unstabilized) is low (at most 30 days storage) as it starts to form grits and thus, the finish of the coating becomes un-acceptable.
TECHNICAL ADVANCEMENTS
The present disclosure described herein above has several technical advantages including, but not limited to, the realization of a stabilized coating composition which:
- has a stable consistency, a finish without grits and desirable wet shelf-life; and
- exhibits high breathability along with anti-bacterial and flame retardant property.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment as well as other embodiments of the disclosure will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.