DESC:FIELD
The present disclosure relates to a primer 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 indicates otherwise.
Green concrete: The term “green concrete”, also known as a “wet concrete”, refers to the concrete before it is fully cured.
Sealer: The term “sealer” refers to a composition that is applied to the green concrete, which functions as a sealant to prevent the evaporation of water, and improves the curing and strength of the green concrete.
Primer: The term “primer” refers to a composition designed to adhere to the surface of a material and improve the adhesion of the top coat to the surface of the material by chemically improving the interface between the two different materials.
Efflorescence: The term “efflorescence” refers to a crystalline or powdery deposit of salts often visible on the surface of concrete, bricks or natural stones.
Substrate: The term “substrate” refers to any surface used for the architectural applications such as concrete, plaster, brick work, masonry, stucco, precast concrete and the like.
Exterior primer: The term “exterior primer” refers to a specially formulated paint which seals the uneven pores and lays the foundation for the finish coats of the paint.
Hydrophobizing agent: The term “hydrophobizing agent” also known as hydrophobic agent refers to a chemical that is prominently used to minimize water absorption and ensure a water-repellent effect.
Moisture scavenger: The term “moisture scavenger” a material used in a polyurethane formulation to minimize the reaction of water with isocyanates by selectively scavenging the moisture/ water from the composition, thus providing longer shelf life of the polyurethane system.
BACKGROUND
The background information herein below relates to the present disclosure but is not necessarily prior art.
A construction project usually completes with the painting of the constructed surfaces as a final step. A typical construction project involves painting of various surfaces such as concrete, brick-work, plasters, and other masonry surfaces. These surfaces require respective surface preparation before the painting. For the application of any paint or coating to be applied on the cementitious surfaces like plasters or concrete, it is to be ensured that the complete curing of concrete is done, so as to prevent the paint or coating from degradation due to surface alkali and efflorescence. However, the curing of the cementitious surfaces requires about 28 days, which is time consuming, but essential for the strength of the construction work. In recent times, due to tight project schedules, project accomplishment with finished painting is necessary, without compromising on the curing time. In such cases, there is a need for a primer/ sealer composition that can be applied on partially cured surfaces.
Further, the conventional primer/ sealant for paints, which acts as an alkali block primer, are based on various synthetic systems. However, most of them are film forming compositions and are not meant for the application on the partially cured surfaces. Failure of the paint was observed in construction projects resulting due to the application of the primer and paints before the complete curing of the surfaces. Sometimes, when primers and paints are applied on partially cured concrete surfaces, the surface alkali migrates through the film, reaches the paint topcoat and affects the shade as the color pigments are sensitive to alkali attack. The products and technologies currently available in the market claim about curing and sealing. However, these products are unable to penetrate deep inside the concrete. Hence, these commercial products are unable to provide resistance to efflorescence, and alkali when applied on the partially cured surfaces.
Therefore, there is felt a need to provide a primer composition that mitigates the drawbacks mentioned hereinabove or at least provide an alternative solution.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows:
An object of the present disclosure is 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 primer composition.
Yet another object of the present disclosure is to provide a primer composition that can be applied on partially cured surfaces or green concrete.
Yet another object of the present disclosure is to provide a primer composition that is alkali resistant, and efflorescence resistant.
Still another object of the present disclosure is to provide a primer composition that enhances the durability of the paint on the substrate.
Yet another object of the present disclosure is to provide a cost-effective and eco-friendly process for the preparation of the primer composition.
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 primer composition. The primer composition comprises 20 mass% to 55 mass% of a polymer solution, 30 mass% to 65 mass% of a penetration aid, 0.05 mass% to 0.3 mass% of an adhesion promoter, 1 mass% to 3 mass% of a siloxane based oligomeric compound, 8 mass% to 12 mass% of a polyisocyanate, and 1 mass% to 5 mass% of a hydrophobizing agent. All the mass percentages are with respect to the total mass of the primer composition.
The present disclosure also relates to a process for the preparation of the primer composition. The process comprises separately preparing a polymer solution by mixing predetermined amounts of a polymer and a fluid medium under stirring at a first predetermined stirring speed at a first predetermined temperature for a first predetermined time period. Sequentially, predetermined amounts of a penetration aid, a hydrophobizing agent, an adhesion promoter, and the polymer solution under stirring at a second predetermined stirring speed at a second predetermined temperature for a second predetermined time period to obtain a resultant mixture. A predetermined amount of siloxane based oligomeric compound is added to the resultant mixture followed by optionally mixing a predetermined amount of a polyisocyanate under stirring at a second predetermined stirring speed at a second predetermined temperature for a second predetermined time period to obtain the primer composition.
BRIEF DESCRIPTION OF THE ACCOMPANYING DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 depicts a freshly prepared test (concrete) panels demonstrating the efflorescence resistance: (a) a test panel coated with a paint directly, (b) a test panel treated with the primer composition of ex. 1 followed by coating with the paint, (c) a test panel treated with the primer composition of ex. 2 followed by coating with the paint; (d) a test panel treated with the primer composition of ex. 3 of the present disclosure followed by coating with the paint, (e) a test panel treated with the primer composition of ex. 4 of the present disclosure followed by coating with the paint, (f) a test panel treated with the primer composition of ex. 5 of the present disclosure followed by coating with the paint, and (g) a test panel treated with primer composition of ex. 6 of the present disclosure followed by coating with the paint;
Figure 2 depicts alkali resistance test results in exterior weather condition for (a) the composition of ex. 6 vs. (b) control;
Figure 3 depicts (a) adhesion of the exterior primer (water-based primer) on a substrate coated with the primer composition of ex. 6 of the present disclosure, and (b) adhesion of the exterior primer on the substrate without coating with the primer composition of the present disclosure (control); and
Figure 4 depicts penetration of individual ingredients of the primer composition of the present disclosure on the cement composite panels (a) chlorinated paraffin wax, (b) Pliolte S5E (a styrene butadiene copolymer), (c) Desmodur 44V20L (a mixture of diphenylmethane-4,4'-diisocyanate (MDI) with isomers and homologues of higher functionality), (d) Pliolite AC 80 (a styrene acrylate copolymer), (e) Bayhydur XP 2655 (Hydrophilic aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI)), and (f) SILRES BS SMK1311 (silicone micro-emulsion concentrate).
DETAILED DESCRIPTION
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
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.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
The application of the conventionally available primer on the substrates before the complete curing of the concrete surface results in paint failure. Sometimes, the surface alkali also migrates through the primer film and reaches the paint topcoat, affecting the shade, as the color pigments are sensitive to alkali attack.
Further, currently available curing membranes or concrete sealers are unable to penetrate to the depth of the substrate and hence do not provide the best combination of curing along with resistance to efflorescence and alkali resistance.
Conventional primer compositions which act as alkali block primers are based on various synthetic systems. However, most of them are film forming compositions and are not meant for the application on the green concrete.
The present disclosure relates to a primer composition and a process for its preparation.
In an aspect, the present disclosure provides a primer composition. The primer composition comprises a polymer solution, a penetration aid, an adhesion promoter, a siloxane based oligomeric compound, a polyisocyanate and a hydrophobizing agent.
In accordance with the present disclosure, the polymer solution is a mixture of 30 mass% to 50 mass% of a polymer, and 50 mass% to 70 mass% of a fluid medium. In an exemplary embodiment, the polymer solution is a mixture of 40 mass% of the polymer and 60 mass% of the fluid medium.
In accordance with the present disclosure, the polymer is a thermoplastic polymer at least one selected from the group consisting of acrylic polymer, styrene butadiene copolymer, styrene acrylate copolymer, vinyl acrylic copolymer, vinyl ethylene copolymer, vinyl chloride and its copolymer. In an exemplary embodiment, the polymer is styrene butadiene copolymer. In another exemplary embodiment, the polymer is styrene acrylate copolymer.
In accordance with an embodiment, the polymer is having a molecular weight in the range of 500 g/mole to 50,000 g/mole.
The thermoplastic polymers used in the present disclosure assist in curing the concrete by forming a film on the substrate.
In accordance with the present disclosure, the fluid medium is at least one selected from the group consisting of aliphatic hydrocarbon, aromatic hydrocarbon, and cycloaliphatic hydrocarbon. Particularly, the fluid medium is at least one selected from the group consisting of xylene, toluene, mineral turpentine (having molecular weight in the range of 100 g/mol to 500 g/mol), cyclobutane, cyclopentane and benzene. In an exemplary embodiment, the fluid medium is xylene.
In accordance with the present disclosure, the polymer solution is present in an amount in the range of 20 mass% to 55 mass% with respect to the total mass of the primer composition. In an exemplary embodiment, the polymer solution is present in the amount of 25 mass% with respect to the total mass of the primer composition. In another exemplary embodiment, the polymer solution is present in the amount of 50 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the penetration aid is a mixture of a co-wetting solvent and a hydrocarbon solvent.
The co-wetting solvent is at least one selected from the group consisting of glycol based compound, diacetone alcohol (4-hydroxy-4-methylpentan-2-one), methyldiacetonalcohol (5-hydroxy-5-methylhexan-3-one), 4-hydroxy-4-methylhexan-2-one, 4-hydroxy 4-methyl pentonone, and diacetone alcohol water (4-hydroxy-4-methylpentan-2-one hydrate). The glycol based compound is at least one selected from the group consisting of glycol ether, glycol ester and glycol ether ester. Particularly, the glycol based compound is at least one selected from the group consisting of ethylene glycol n-butyl ether (butyl cellosolve), diethylene glycol mono n-butyl ether (butyl carbitol), ethyl carbitol acetate, ethylene glycol mono n-butyl ether acetate, diethylene glycol mono n-butyl ether acetate, and propylene glycol mono methyl ether. In an exemplary embodiment, the penetration aid is a mixture of xylene and diacetone alcohol in a mass ratio of 80:20.
The hydrocarbon solvent is at least one selected from the group consisting of aliphatic hydrocarbon, aromatic hydrocarbon, and cycloaliphatic hydrocarbon. Particularly, the hydrocarbon solvent is at least one selected from the group consisting of xylene, mineral turpentine, toluene, cyclobutane, cyclopentane and benzene.
In accordance with the present disclosure, the penetration aid is present in an amount in the range of 30 mass% to 65 mass% with respect to the total mass of the primer composition. In accordance with an exemplary embodiment, the penetration aid is present in the amount of 60.4 mass% with respect to the total mass of the primer composition. In accordance with another exemplary embodiment, the penetration aid is present in the amount of 57.7 mass% with respect to the total mass of the primer composition. In accordance with still another exemplary embodiment, the penetration aid is present in the amount of 32.7 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the adhesion promoter is a functionalized silane selected from the group consisting of an epoxy functional silane oligomer having a polyfunctional structure bearing gamma-glycidoxy propyl epoxide ring, monomeric organo silane, and oligomeric organo silane. In the exemplary embodiments, the adhesion promoter is an epoxy functional silane oligomer having a polyfunctional structure bearing gamma-glycidoxy propyl epoxide ring.
In accordance with the present disclosure, the adhesion promoter is present in an amount in the range of 0.05 mass% to 0.3 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the adhesion promoter is present in the amount of 0.1 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the siloxane based oligomeric compound is at least one selected from the group consisting of silane-siloxane, silicate, siliconate, silicone, and alkoxy silane. The alkoxy silane is at least one selected from the group consisting of polydimethyloxysiloxane, methyltrimethoxysilane, alkyltrialkoxysilane and tetraethoxysilane.
In accordance with the present disclosure, the siloxane based oligomeric compound is present in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the siloxane based oligomeric compound is present in the amount of 2 mass% with respect to the total mass of the primer composition.
The siloxane based oligomeric compound of the present disclosure is solvent-less and of micro-emulsion grade. In the exemplary embodiments, the siloxane based oligomeric compound is silicone micro-emulsion concentrate (SILRES BS SMK 1311).
The siloxane based oligomeric compound used in the present disclosure aids in the adhesion of the polymers with the concrete substrate. The micro-emulsion form of the siloxane based oligomeric compound wets the green concrete easily. The siloxane based oligomeric compound hydrolyzes and reacts with the surface hydroxyl of the substrate.
In accordance with the present disclosure, the polyisocyanate is a modified hydrophilic polyisocyanate at least one selected from the group consisting of hexamethylene diisocyanate (HDI) based hydrophilic aliphatic polyisocyanate (molecular weight in the range of 650 g/mol to 1000 g/mol), diphenylmethane-4,4'-diisocyanate (MDI) based polymeric isocyanate (molecular weight in the range of 500 g/mol to 1500 g/mol), diphenylmethane-4, 4'-diisocyanate (MDI) based oligomeric isocyanate (molecular weight in the range of 500 g/mol to 1500 g/mol), toluene diisocyanate toluene diisocyanate oligomer, isophorone diisocyanate (IPDI), and isophorone diisocyanate oligomer. In an exemplary embodiment, the polyisocyanate is hexamethylene diisocyanate (HDI) based hydrophilic aliphatic polyisocyanate (Bayhydur XP 2655). In another exemplary embodiment, the polyisocyanate is a mixture of diphenylmethane-4,4'-diisocyanate (MDI) with isomers (Desmodur 44V20L).
In accordance with the present disclosure, the polyisocyanate is present in an amount in the range of 8 mass% to 12 mass% with respect to the total mass of the primer composition. In an exemplary embodiment, the polyisocyanate is present in the amount of 10 mass% with respect to the total mass of the primer composition.
The polyisocyanates used in the present disclosure, being low molecular weight compounds (molecular weight in the range of 500 g/mol to 1000 g/mol), penetrate deep inside the pores of the concrete substrate. The polyisocyanates react with water and form polyurea which not only consume the surface water but also form strong bond with the surface. The polyisocyanate plays specific role in encapsulating the substrate. The hydrophilic modification of the polyisocyanate allows the penetration of polyisocyanate in the wet substrate, which plays a key role in the performance of the primer composition.
In accordance with the present disclosure, the hydrophobizing agent is at least one selected from the group consisting of stearic acid, oleic acid, rosin acid, zinc stearate, calcium stearate, zinc oleate, and calcium oleate. In an exemplary embodiment, the hydrophobizing agent is stearic acid.
The hydrophobizing agent is present in an amount in the range of 1 mass% to 5 mass% with respect to the total mass of the primer composition. In an exemplary embodiment, the hydrophobizing agent is present in the amount of 3 mass% with respect to the total mass of the primer composition.
The hydrophobizing agent used in the present disclosure aids in water repellency and residual alkali reactivity. The hydrophobizing agent plays key role in resistance of alkali on the substrate.
In accordance with an embodiment of the present disclosure, the primer composition comprises at least one additive. The additive is selected from a wetting agent, a plasticizer, a moisture scavenger and a catalyst.
In accordance with the present disclosure, the wetting agent is at least one selected from the group consisting of fluoro acrylate, fluorocarbon modified acrylate, and fluorocarbon surfactant. In an exemplary embodiment, the wetting agent is fluorocarbon modified acrylate.
In accordance with the present disclosure, the wetting agent is present in an amount in the range of 0.05 mass% to 0.2 mass% with respect to the total mass of the primer composition. In an exemplary embodiment, the wetting agent is present in the amount of 0.1 mass% with respect to the total mass of the primer composition.
The wetting agent used in the present disclosure assists in wetting of the green concrete more efficiently.
In accordance with the present disclosure, the plasticizer is a chlorinated paraffin wax having chlorination degree in the range of 40% to 60%. In the exemplary embodiments, the plasticizer is chlorinated paraffin wax with 52% chlorination.
In accordance with the present disclosure, the plasticizer is present in an amount in the range of 1 mass% to 5 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the plasticizer is present in the amount of 2 mass% with respect to the total mass of the primer composition.
In accordance with an embodiment of the present disclosure, the primer composition comprises a moisture scavenger. The moisture scavenger is at least one selected from the group consisting of trimethylorthoformate, triethylorthoformate, tripropylorthoformate, and tributylorthoformate. In an exemplary embodiment, the moisture scavenger is triethylorthoformate.
In accordance with the present disclosure, the moisture scavenger is present in an amount in the range of 0.1 mass% to 0.5 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the moisture scavenger is present in the amount of 0.2 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the catalyst is a non-tin catalyst selected from the group consisting of a metal complex of carboxylate and a metal complex of amine. The metal in the complexes is at least one selected from the group consisting of zinc, zirconium, calcium, and bismuth. In accordance with an embodiment of the present disclosure, the catalyst is carboxylate and amine complex of zinc neodecanoate. In the exemplary embodiments, the catalyst is zinc amine complex.
In accordance with the present disclosure, the catalyst is present in an amount in the range of 0.05 mass% to 0.5 mass% with respect to the total mass of the primer composition. In an exemplary embodiment, the catalyst is present in the amount of 0.1 mass% with respect to the total mass of the primer composition. In another exemplary embodiment, the catalyst is present in the amount of 0.2 mass% with respect of the total mass of the primer composition.
The catalyst used in the present disclosure aid in moisture curing.
In accordance with an embodiment of the present disclosure, the primer composition is packed in a single pack.
In accordance with another embodiment of the present disclosure, the primer composition is packed in two separate packs, wherein polyisocyanate is mixed at the time of application.
The primer composition of the present disclosure is for “Green concrete”, which can be applied on the newly constructed surface (plaster or concrete) just after setting of the surface.
The primer composition of the present disclosure can tolerate the surface moisture (up to 50%) without any negative effect on the curing or subsequent primer performance. The primer composition of the present application also acts as a sealer.
The primer composition of the present disclosure imparts excellent alkali resistance which prevails during the curing of the plaster or concrete. The primer composition of the present disclosure imparts excellent efflorescence resistance thus prevent the paint system from undergoing deterioration. The primer composition of the present disclosure does not affect the adhesion negatively of the subsequent primer/ paint. Once the primer composition of the present disclosure is applied, it prevents the evaporation of the water (up to 50%) from the surface. Hence, it helps the concrete curing and does not require separate efforts for the curing of the concrete/ plaster. The primer composition of the present disclosure is robust against attack of alkali, water, efflorescence and the like. Hence, it enhances the durability of the paint system.
In another aspect, the present disclosure provides a process for the preparation of a primer composition. The detailed process is described as follows:
Separately, a polymer solution is prepared by mixing predetermined amounts of a polymer and a fluid medium under stirring at a first predetermined stirring speed at a first predetermined temperature for a first predetermined time period to obtain a polymer solution (step (i)).
In accordance with the present disclosure, the polymer is a thermoplastic polymer at least one selected from the group consisting of acrylic polymer, styrene butadiene copolymer, styrene acrylate copolymer, vinyl acrylic copolymer, vinyl ethylene copolymer, vinyl chloride and its copolymer. In an exemplary embodiment, the polymer is styrene butadiene copolymer. In another exemplary embodiment, the polymer is styrene acrylate copolymer.
In accordance with the present disclosure, the predetermined amount of polymer is in the range of 30 mass% to 50 mass% with respect to the total mass of the polymer solution. In an exemplary embodiment, the predetermined amount of polymer is 40 mass% with respect to the total mass of the polymer solution.
In accordance with the present disclosure, the predetermined amount of fluid medium is in the range of 50 mass% to 80 mass% with respect to the total mass of the polymer solution. In an exemplary embodiment, the predetermined amount of fluid medium is in the range of 60 mass% with respect to the total mass of the polymer solution.
In accordance with the present disclosure, the fluid medium is at least one selected from the group consisting of aliphatic hydrocarbon, aromatic hydrocarbon, and cycloaliphatic hydrocarbon. Particularly, the fluid medium is at least one selected from the group consisting xylene, toluene, mineral turpentine (having molecular weight in the range of 100 g/mol to 500 g/mol), cyclobutane, cyclopentane and benzene. In an exemplary embodiment, the fluid medium is xylene.
In accordance with the present disclosure, the first predetermined stirring speed is in the range of 200 rpm to 800 rpm. In an exemplary embodiment, the first predetermined stirring speed is 200 rpm. In another exemplary embodiment, the first predetermined stirring speed is 650 rpm.
In accordance with the present disclosure, the first predetermined temperature is in the range of 25 ºC to 35 ºC. In an exemplary embodiment, the first predetermined temperature is 30 ºC.
In accordance with the present disclosure, the first predetermined time period is in the range of 10 minutes to 15 hours. In an exemplary embodiment, the first predetermined time period is 8 hours. In another exemplary embodiment, the first predetermined time period is 20 minutes.
Predetermined amounts of a penetration aid, a hydrophobizing agent, an adhesion promoter and the polymer solution are sequentially mixed under stirring at a second predetermined stirring speed at a second predetermined temperature for a second predetermined time period to obtain a resultant mixture (step (ii)).
In accordance with the present disclosure, the penetration aid is a mixture of a co-wetting solvent and a hydrocarbon solvent.
The hydrocarbon solvent is at least one selected from the group consisting of aliphatic hydrocarbon, aromatic hydrocarbon, and cycloaliphatic hydrocarbon. Particularly, the hydrocarbon solvent is at least one selected from the group consisting of xylene, mineral turpentine, toluene, cyclobutane, cyclopentane and benzene.
The co-wetting solvent is at least one selected from the group consisting of glycol based compound, diacetone alcohol (4-hydroxy-4-methylpentan-2-one), methyldiacetonalcohol (5-hydroxy-5-methylhexan-3-one), 4-hydroxy-4-methylhexan-2-one, 4-hydroxy 4-methyl pentonone, and diacetone alcohol water (4-hydroxy-4-methylpentan-2-one hydrate). The glycol based compound is at least one selected from the group consisting of glycol ether, glycol ester and glycol ether ester. Particularly, the glycol based compound is at least one selected from the group consisting of ethylene glycol n-butyl ether (butyl cellosolve), diethylene glycol mono n-butyl ether (butyl carbitol), ethyl carbitol acetate, ethylene glycol mono n-butyl ether acetate, diethylene glycol mono n-butyl ether acetate, and propylene glycol mono methyl ether.
In an exemplary embodiment, the penetration aid is a mixture of xylene and diacetone alcohol in a mass ratio of 80:20.
In accordance with the present disclosure, the penetration aid is present in an amount in the range of 50 mass% to 65 mass% with respect to the total mass of the primer composition. In accordance with an exemplary embodiment, the penetration aid is present in the amount of 60.4 mass% with respect to the total mass of the primer composition. In accordance with another exemplary embodiment, the penetration aid is present in the amount of 57.7 mass% with respect to the total mass of the primer composition. In accordance with still another exemplary embodiment, the penetration aid is present in the amount of 32.7 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the hydrophobizing agent is at least one selected from the group consisting of stearic acid, oleic acid, rosin acid, zinc stearate, calcium stearate, zinc oleate and calcium oleate. In an exemplary embodiment, the hydrophobizing agent is stearic acid.
The hydrophobizing agent is present in an amount in the range of 1 mass% to 5 mass% with respect to the total mass of the primer composition. In an exemplary embodiment, the hydrophobizing agent is present in the amount of 3 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the adhesion promoter is a functionalized silane at least one selected from an epoxy functional silane oligomer having a polyfunctional structure bearing gamma-glycidoxy propyl epoxide ring, monomeric organo silane, and oligomeric organo silane. In the exemplary embodiments, the adhesion promoter is an epoxy functional silane oligomer having a polyfunctional structure bearing gamma-glycidoxy propyl epoxide ring (CoatOsil MP 200).
In accordance with the present disclosure, the adhesion promoter is present in an amount in the range of 0.05 mass% to 0.3 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the adhesion promoter is present in the amount of 0.1 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the second predetermined stirring speed is in the range of 200 rpm to 400 rpm. In an exemplary embodiment, the second predetermined stirring speed is 300 rpm.
In accordance with the present disclosure, the second predetermined temperature is in the range of 25 ºC to 35 ºC. In an exemplary embodiment, the second predetermined temperature is 30 ºC.
In accordance with the present disclosure, the second predetermined time period is in the range of 10 minutes to 60 minutes. In an exemplary embodiment, the second predetermined time period is 30 minutes.
A predetermined amount of siloxane based oligomeric compound is added to the resultant mixture followed by optionally mixing a predetermined amount of polyisocyanate under stirring at second predetermined stirring speed at the second predetermined temperature for the second predetermined time period to obtain the primer composition (step (iii)).
In accordance with the present disclosure, the siloxane based oligomeric compound is a solvent-less silicone microemulsion concentrate based on silanes and siloxanes (SILRES® BS SMK 1311).
In accordance with the present disclosure, the siloxane based oligomeric compound is present in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the siloxane based oligomeric compound is present in the amount of 2 mass% with respect to the total mass of the primer composition.
The siloxane based oligomeric compound of the present disclosure is solvent-less and of micro-emulsion grade. In an exemplary embodiment, the siloxane based oligomeric compound is silicone micro-emulsion concentrate (SILRES BS SMK 1311).
In accordance with the present disclosure, the polyisocyanate is a modified hydrophilic polyisocyanate at least one selected from the group consisting of hexamethylene diisocyanate (HDI) based hydrophilic aliphatic polyisocyanate (molecular weight in the range of 650 g/mol to 1000 g/mol), diphenylmethane-4,4'-diisocyanate (MDI) based polymeric isocyanate (molecular weight in the range of 500 g/mol to 1500 g/mol), diphenylmethane-4, 4'-diisocyanate (MDI) based oligomeric isocyanate (molecular weight in the range of 500 g/mol to 1500 g/mol), toluene diisocyanate and toluene diisocyanate oligomer, isophorone diisocyanate (IPDI), and isophorone diisocyanate oligomers. In an exemplary embodiment, the polyisocyanate is hexamethylene diisocyanate (HDI) based hydrophilic aliphatic polyisocyanate (Bayhydur XP 2655).
In accordance with the present disclosure, the polyisocyanate is present in an amount in the range of 8 mass% to 12 mass% with respect to the total mass of the primer composition. In an exemplary embodiment, the polyisocyanate is present in the amount of 10 mass% with respect to the total mass of the primer composition.
In accordance with an embodiment of the present disclosure, the predetermined amount of polyisocyanate is mixed at the time of application.
In accordance with the present disclosure, a predetermined amount of an additive is added in step (ii) and (iii). The additive is at least one selected from a plasticizer, a wetting agent, a moisture scavenger and a catalyst.
In accordance with the present disclosure, the plasticizer is a chlorinated paraffin wax with chlorination degree in the range of 40% to 60%. In the exemplary embodiments, the plasticizer is chlorinated paraffin wax with 52% chlorination.
In accordance with the present disclosure, the plasticizer is present in an amount in the range of 1 mass% to 5 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the plasticizer is present in the amount of 2 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the wetting agent is at least one selected from the group consisting of fluoro acrylate, fluorocarbon modified acrylate, and fluorocarbon surfactant. In the exemplary embodiments, the wetting agent is fluorocarbon modified acrylate.
In accordance with the present disclosure, the wetting agent is present in an amount in the range of 0.05 mass% to 0.2 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the wetting agent is present in the amount of 0.1 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the moisture scavenger is at least one selected from the group consisting of trimethylorthoformate, triethylorthoformate, tripropylorthoformate, and tributylorthoformate. In an exemplary embodiment, the moisture scavenger is triethylorthoformate.
In accordance with the present disclosure, the moisture scavenger is present in an amount in the range of 0.1 mass% to 0.5 mass% with respect to the total mass of the primer composition. In the exemplary embodiments, the moisture scavenger is present in the amount of 0.2 mass% with respect to the total mass of the primer composition.
In accordance with the present disclosure, the catalyst is a non-tin catalyst selected from the group consisting of a metal complex of carboxylate and a metal complex of amine. The metal in the complexes is at least one selected from the group consisting of zinc, zirconium, calcium, and bismuth. In accordance with an embodiment of the present disclosure, the catalyst is carboxylate and amine complex of zinc neodecanoate. In an exemplary embodiment, the catalyst is zinc amine complex.
In accordance with the present disclosure, the catalyst is present in an amount in the range of 0.05 mass% to 0.5 mass% with respect to the total mass of the primer composition. In an exemplary embodiment, the catalyst is present in the amount of 0.1 mass% with respect to the total mass of the primer composition. In another exemplary embodiment, the catalyst is present in the amount of 0.2 mass% with respect of the total mass of the primer composition.
The primer composition in accordance with the present disclosure can be made in a single pack (shorter shelf life) as well as two packs (longer shelf life). In two pack system, the polyisocyanates can be supplied in two separate containers. The primer composition in the single pack has a shelf life in the range of 4 months to 6 months. The primer composition in the two packs has a shelf life in the range of 1 year to 3 years.
The primer composition of the present disclosure can be applied on the partially cured surfaces. Hence, the requirement of complete curing before the painting becomes non-essential. Thus, the primer composition of the present disclosure saves the time required for the surface preparation.
The primer composition of the present disclosure enables deeper substrate penetration and curing, in comparison with the conventionally available water-based or solvent-based primer compositions.
The primer composition of the present disclosure shows excellent film-forming property. The primer composition ensures concrete curing while avoiding the use of water curing. The primer composition further exhibits alkali and efflorescence resistance due to blocking of capillaries and prevents the migration of moisture to the surface. The primer composition of the present disclosure, upon application, provides an excellent encapsulation of cementitious composition and provides excellent alkali and efflorescence resistance with enhanced durability.
The primer composition of the present disclosure can be applied on the partially cured surfaces. It tolerates the surface moisture without any negative effect on the curing or subsequent primer performance and imparts excellent efflorescence resistance, thus prevents deterioration of the coating. The primer composition of the present disclosure also improves the adhesion of the subsequent primer/ paint. During the curing of the plaster or concrete, the primer composition imparts excellent alkali resistance. The primer composition of the present disclosure when applied on the green concrete prevents the evaporation of the water from the surface. Hence, it helps the concrete curing and does not require separate efforts for the curing of the concrete/ plaster. Thus, the primer composition of the present disclosure enhances the durability of the paint.
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 the industrial scale.
Experimental details:
A process for the preparation of the primer composition in accordance with the present disclosure
Initially, the separate solutions of 40 mass% of polymer (Pliolite AC 80 or Pliolite S5E) (see Sr. No. 6 and 7 respectively in Table 1) were prepared in xylene under stirring at about 200 rpm 8 hours at a temperature of 30ºC for to obtain a polymer solution. When the stirring speed was 650 rpm, the polymer solution was prepared in 20 minutes.
The components of Sr. nos. 1 to 12 as given below in table 1 were added in the same sequence in a vessel and under stirring at 300 rpm at a temperature of 30ºC for 20 minutes. After the addition of all the ingredients, stirring was continued for further 10 minutes. Then the stirring was discontinued, and the compositions were transferred to metal containers and used for performance evaluation. For single pack system, all the materials were added in same vessel and for two pack system the polyisocyanates (items 11 and 12 were kept separate and were added just before the application of the composition on the substrate).
Table 1: Various compositions of the primer
Sr. no. Components Class of components Amounts in mass%
Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6 Ex. 7
1 Mixture of xylene + diacetone alcohol, (80:20) by mass Penetration aid 73 73 60.4 60.4 60.4 57.7 32.7
2 Stearic Acid Hydrophobizing agent 3.0 3.0
3 CoatOsil MP 200 (an epoxy functional silane oligomer having a polyfunctional structure
bearing gamma-glycidoxy propyl epoxide ring) Adhesion promoter - - 0.1 0.1 0.1 0.1 0.1
4 Chlorinated paraffin wax 52 % chlorination Plasticizer 2.0 2.0 2.0 2.0 2.0 2.0 2.0
5 Pat Add LE 1477 (fluorocarbon modified polyacrylate) Wetting agent - - 0.1 0.1 0.1 0.1 0.1
6 Pliolite AC 80 (a styrene acrylate copolymer) (40 mass% solution in xylene) Thermoplastic polymer solution 25 25 25 25 25 50
7 Pliolite S5E (a styrene butadiene copolymer) (40 mass% solution in xylene) Thermoplastic polymer solution 25
8 SILRES BS SMK 1311 (silicone microemulsion concentrate) Siloxane based oligomeric compound (Micro-emulsion grade) - - 2 2 2 2 2
9 triethylorthoformate Moisture scavenger - - 0.2 0.2 0.2
10 K-KAT® XK-661 (Zn-amine complex; non-tin catalyst) Catalyst - - 0.2 0.2 0.2 0.1 0.1
11 Bayhydur XP 2655 (Hydrophilic aliphatic polyisocyanate based on hexamethylene diisocyanate (HDI)) Polyisocyanate - - 10 - 5 10 10
12 Desmodur 44V20L (a mixture of
diphenylmethane-4,4'-diisocyanate (MDI) with isomers and homologues of
higher functionality) Polyisocyanate - - - 10 5
Total 100 100 100 100 100 100 100
*Ex. 1 and Ex. 2 are comparative examples; Ex. 3 to Ex. 7 are primer compositions of the present disclosure
Evaluation of the primer compositions prepared in accordance with the present disclosure
Table 2: Physical properties of primer compositions
Sr. No. Parameter Result
Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Ex. 6
1 % solids 25 25 25 25 25 28
2 Surface tension 29.16 29.67 28.55 29.08 29.46 29.12
3 Specific gravity at 25 ºC 0.980 0.980 0.930 0.930 0.9130 0.9160
4 Substrate penetration ease (gms/ sq. feet) 18.20 18.84 21.00 19.55 20.58 21.11
5 Viscosity (sec.) B4 cup 30 30 22 22 22 21

The lower viscosity of Ex. 6 gave best penetration in the substrate so as to support best alkali resistance and efflorescence resistance.
Performance properties of the primer compositions prepared in accordance with the present disclosure
The primer compositions as prepared above were directly applied on the respective test panels (substrate) by using a brush or a roller. The substrate saturated application (liberal coat) was applied to ensure the maximum penetration in the surface. The primer compositions were applied on the substrate by brush / roller to ensure that all the pores are completely filled which can be seen by little excess liquid on the surface.
(A) Performance data:
(1) Efflorescence resistance:
The primer compositions were applied on the newly prepared concrete panels, once the substrate was set enough for mar resistance (green strength) for 4 to 6 hours depending on the environmental condition. Subsequently, the panels were coated with the latex paint having alkali sensitive pigment and allowed to cure for 7 days before putting it in an aqueous salt solution (10 mass% of NaCl). The bottom side of the panel was immersed in the solution to allow the capillary absorption of salts into substrate.
The failure was observed in terms of the color fading/ white efflorescence on the paint film. Fig. 1 depicts the test panels showing the efflorescence resistance of ex. no. 1 to ex. no. 6 in comparison to uncoated freshly prepared concrete panel. Ex. no. 6 (see Fig. 1(g)) showed very good efflorescence resistance. However, ex. 6 with additional stearic acid was best in terms of the performance against the other experimental sets.
(2) Alkali Resistance:
The primer composition of ex. 6 was applied on the newly prepared concrete panels once the substrate was set enough for mar resistance (green strength) for 4 to 6 hours depending on the environmental condition. Subsequently, the panels were coated with the latex paint having alkali sensitive pigment and allowed to cure for 7 days before putting it in an alkali solution (10% of NaOH). The bottom side of the panel was immersed in a solution to allow the capillary absorption of alkali into the concrete panel for one month. The panels were then kept in exterior weather condition for one month. The failure was observed in terms of the color fading/ white efflorescence on the paint film. There was no color fading or white efflorescence observed when the primer composition of ex. 6 when treated with alkali (see Fig. 2(a)).
The latex paint having alkali sensitive pigment was applied on the newly formed concrete block and these coated blocks were exposed to 10 % alkali solution and kept in exterior weather condition for one month to obtain a control. The control showed the fading due to the surface alkali whereas the primer compositions of the present disclosure did not show any color change (see Fig 2 (b)). This confirms the improved durability of the paint due to the alkali block primer.

(B) Adhesion of exterior primer on sealed surfaces
The test panels in Fig. 3a show the adhesion of the water based primer (exterior primer) over the primer composition of the present disclosure (ex. 6). There was no difference in adhesion performance of the exterior primer when compared with the test panel surface without the primer of the present disclosure/sealer (control) (see Fig. 3b). Hence, there was no any negative effect on the paint adhesion due to application of the primer of the present disclosure.
(C) Substrate penetration study
The individual ingredients of the primer composition of the present disclosure (10 mass %) were dissolved in xylene (fortified with solvent soluble dye such as BASF, Neozapon red, yellow, brown, and the like) and the relative substrate penetration was measured on the cement composite panels. The cement composite panels were dipped in a colour solution (3 minutes) of the respective ingredients and the depth of the penetration was measured in mm of the penetration and recorded in the Table 3 below. There was a highest penetration by Bayhydur XP 2655 due to its hydrophilic modification. The penetration of resins Pliolite S5E and Pliolite AC 80 was lowest due to their high molecular weights. Hence, the individual ingredients of the primer composition of the present disclosure showed poor alkali resistance and efflorescence resistance (see Fig. 4).
Table 3: A comparative table providing the substrate penetration in the composition of the present disclosure and its individual ingredients
Sr. No. 10 mass% solution of the ingredients in xylene Penetration depth (in mm)
1 Chlorinated paraffin wax 10 mm
2 Pliolite S5E 5 mm
3 Desmodur 44V20L 12 mm
4 Pliolite AC 80 5 mm
5 Bayhydur XP 2655 12 mm
6 SILRES BS SMK 1311 8 mm
7 Primer composition of Ex. 6 5 mm
8 Primer composition of Ex. 1 1 mm

The primer composition in ex. 6 showed 5 times more penetration against the conventional resin based primers (ex. 1) proving the best substrate penetration.
(D) A study of the compressive strength (ASTM C 39) of the primer composition of the present disclosure
In this experiment, the fresh concrete blocks were prepared. A first set of the blocks was left uncoated for air curing. A second set of blocks was immersed in water for typical water curing. A third set of the blocks were applied with the primer composition of the present disclosure. Table 4 below shows compressive strength results of the aforesaid three sets.
Table 4

S.N.
Experimental conditions Compressive Strength (MPa)
3 Day 7 Day 14 Day 28 Day
1 Dry concrete cube (control)- air curing 12.2 30.0 34.69 35.7
2 Concrete cube (control)- water curing 13.26 34.92 37.98 48.68
3 Concrete cube coated with primer composition (Ex. 6) 13.08 32.80 34.96 38.28
4 Concrete cube coated with primer composition (Ex. 7) 13.20 33.25 36.38 42.7

Table 4 clearly showed the role of the primer composition of the present disclosure in concrete curing. Thus, it can be concluded that the primer composition of the present disclosure was utilized for curing the concrete membrane. The data above showed that the primer composition ex. 6 demonstrated curing of the concrete block without any water, whereas the improved strength depicts the water retention ability as curing compound/ membrane. However, the primer composition of ex. 7 is derived from ex. 6, wherein in ex. 7 additional curing is achieved with the increased polymer content which leads to improved binding.
(E) Water Vapor permeability (WVP) and Water retention
1. Water vapor permeability: A commercial cement putty compositions were casted at various dry film thicknesses such as 1 mm, 2 mm, and 3 mm and dried for 7 days. After curing of the putties, the primer composition of ex. 6 of the present disclosure was applied on these putties. Once cured, the cured putties coated with a commercial exterior primer composition were fixed on the permeability cup and were kept in chamber with controlled humidity and temperature with one control (uncoated) system. Permeability cup is water vapor permeability cup used for assessing the ability of the film to allow the water vapor to get transferred. As a membrane for concrete curing, less water vapor permeability is preferred. Below data clearly showed the difference in water vapor permeability. The data demonstrated that the primer composition of the present disclosure showed reduced water vapor permeability, indicating that the primer composition can be a good membrane composition. At the same time, residual permeability maintained the film for the breathable film of the paint. As mentioned above, the primer composition of the present disclosure is a good membrane compound at the same time; the little permeability ensures the substrate breathability for the sustained paint performance.
WVP of the control was 2.50 gm/ft2/h, whereas the WVP of the primer composition of the present disclosure was 0.432251287 gm/ft2/h.
2. Water retention: Fresh mortar cubes were prepared and after 24 hours of casting the mortar cubes they were divided into three groups. Out of that one group coated with the primer composition of ex. 6 and kept for air curing, another group coated with the primer composition of ex. 7 and kept for air curing, and a third group of uncoated mortar cubes kept for air curing (control). Weight of all the cubes were noted down for 28 days to study the reduction in water evaporation due to application of the primer composition.
Table 5
Water Retention / Water Loss Data in Percentage
Sr. No. Experiments Control Cubes Coated by primer composition of the present disclosure (Ex. 6) Cubes Coated by primer composition of the present disclosure (Ex. 7)
1 3 days 53.17 27.79 24.99
2 7 days 71.37 52.35 46.52
3 14 days 85.13 64.31 52.79
4 28 days 100 82.25 71.38
5 Total water loss (gm) 41.03 33.74 29.28
6 Total water retention (gm) 0.00 7.28 11.74
7 Water retention % 0.00 17.75 28.619

The data mentioned in the above table showed that the increased percentage of water retention was possible by the application of the primer composition of the present disclosure. Hence, the primer composition of the present disclosure can be used as curing membrane.
(F) Anti – algal performance improvement
The algal resistance test was done by the chamber test. ISTM/MB/3.5 was a quantitative method. The test panels were exposed to the accelerated test condition and the rating was given based on the standard test process. Chamber test is the anti- algal chamber test done in the lab by artificially creating the environment for algal pores growth. The test panels were coated with the primer composition of the present disclosure, inserted in the chamber and tested against the uncoated test panel.
Table 6
S. No. Sample Description Anti-algal performance rating*
1 Test panel coated with primer composition of the present disclosure (ex. 6) 5
2 Uncoated test panel (control) 3
*Scale 0 (poor performance) to 10 (best performance)
The primer composition of ex. 6 showed improved anti- algal performance due to the surface hydrophobicity and good water repellency.
The primer composition of ex. 7 of the present disclosure showed improved curing and membrane forming properties as compared to the primer composition of ex. 6 of the present disclosure.
TECHNICAL ADVANCEMENTS
The present disclosure described hereinabove has several technical advantages including, but not limited to, the realization of, the primer composition that:
• has excellent alkali and efflorescence resistance;
• enhances the durability of the paint;
• prevents the evaporation of the water from the surface and does not require separate efforts for the curing of the concrete/ plaster;
• can be applied to the substrate after initial setting of cement for overnight; and
the process for the preparation of the primer composition is
• simple, cost-effective, and eco-friendly.
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.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
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. ,CLAIMS:WE CLAIM:
1. A primer composition comprising:
a. 20 mass% to 55 mass% of a polymer solution;
b. 30 mass% to 65 mass% of a penetration aid;
c. 0.05 mass% to 0.3 mass% of an adhesion promoter;
d. 1 mass% to 3 mass% of a siloxane based oligomeric compound;
e. 8 mass% to 12 mass% of a polyisocyanate; and
f. 1 mass% to 5 mass% of a hydrophobizing agent;
wherein all the mass percentages are with respect to the total mass of the primer composition.
2. The primer composition as claimed in claim 1 comprising at least one additive selected from a wetting agent, a plasticizer, a moisture scavenger and a catalyst.
3. The primer composition as claimed in claim 1, wherein said polymer solution is a mixture of 30 mass% to 50 mass% of a polymer and 50 mass% to 70 mass% of a fluid medium; said polymer is a thermoplastic polymer selected from the group consisting of acrylic polymer, styrene butadiene copolymer, styrene acrylate copolymer, vinyl acrylic copolymer, vinyl ethylene copolymer, vinyl chloride and its copolymer; said fluid medium is at least one selected from the group consisting of xylene, toluene, mineral turpentine, cyclobutane, cyclopentane, and benzene.
4. The primer composition as claimed in claim 1, wherein said penetration aid is a mixture of a co-wetting solvent and a hydrocarbon solvent; said hydrocarbon solvent is at least one selected from the group consisting of xylene, mineral turpentine, toluene, cyclobutane, cyclopentane and benzene; and said co-wetting solvent is at least one selected from the group consisting of glycol based compound, diacetone alcohol, methyldiacetonalcohol, 4-hydroxy-4-methylhexan-2-one, 4-hydroxy 4-methyl pentonone, and diacetone alcohol water; wherein said glycol based compound is at least one selected from the group consisting of ethylene glycol n-butyl ether (butyl cellosolve), diethylene glycol mono n-butyl ether (butyl carbitol), ethyl carbitol acetate, ethylene glycol mono n-butyl ether acetate, diethylene glycol mono n-butyl ether acetate, and propylene glycol mono methyl ether.
5. The primer composition as claimed in claim 1, wherein said adhesion promoter is a functionalized silane selected from the group consisting of an epoxy functional silane oligomer having a polyfunctional structure bearing gamma-glycidoxy propyl epoxide ring (CoatOsil MP 200), monomeric organo silane, and oligomeric organo silane.
6. The primer composition as claimed in claim 1, wherein said siloxane based oligomeric compound is a solvent-less silicone microemulsion concentrate based on silanes and siloxanes (SILRES® BS SMK 1311).
7. The primer composition as claimed in claim 1, wherein said polyisocyanate is a modified hydrophilic polyisocyanate and is at least one selected from the group consisting of hexamethylene diisocyanate (HDI) based hydrophilic aliphatic polyisocyanate (Bayhydur XP 2655), diphenylmethane-4, 4'-diisocyanate (MDI) based polymeric isocyanate (Desmodur 44V20L), diphenylmethane-4, 4'-diisocyanate (MDI) based oligomeric isocyanate, toluene diisocyanate, toluene diisocyanate oligomer, isophorone diisocyanate (IPDI) and isophorone diisocyanate oligomer.
8. The primer composition as claimed in claim 1, wherein said hydrophobizing agent is at least one selected from the group consisting of stearic acid, oleic acid, rosin acid, zinc stearate, calcium stearate, zinc oleate, and calcium oleate.
9. The primer composition as claimed in claim 2, wherein said wetting agent is at least one selected from the group consisting of fluoro acrylate, fluorocarbon modified acrylate (Pat Add LE 1477), and fluorocarbon surfactant; and said wetting agent is present in an amount in the range of 0.05 mass% to 0.2 mass% with respect to the total mass of the primer composition.
10. The primer composition as claimed in claim 2, wherein said plasticizer is a chlorinated paraffin wax; and said plasticizer is present in an amount in the range of 1 mass% to 5 mass% with respect to the total mass of the primer composition.
11. The primer composition as claimed in claim 2, wherein said moisture scavenger is at least one selected from the group consisting of trimethylorthoformate, triethylorthoformate, tripropylorthoformate and tributylorthoformate; and said moisture scavenger is present in an amount in the range of 0.1 mass% to 0.5 mass% with respect to the total mass of the primer composition.
12. The primer composition as claimed in claim 2, wherein said catalyst is a non-tin catalyst selected from the group consisting of a metal complex of carboxylate and a metal complex of amine; said metal is at least one selected from the group consisting of zinc, zirconium, calcium, and bismuth; and said catalyst is present in an amount in the range of 0.05 mass% to 0.5 mass% with respect to the total mass of the primer composition.
13. A process for the preparation of a primer composition, said process comprising the following steps:
(i) separately, preparing a polymer solution by mixing predetermined amounts of a polymer and a fluid medium under stirring at a first predetermined stirring speed at a first predetermined temperature for a first predetermined time period;
(ii) sequentially mixing predetermined amounts of a penetration aid, a hydrophobizing agent, an adhesion promoter and said polymer solution under stirring at a second predetermined stirring speed at a second predetermined temperature for a second predetermined time period to obtain a resultant mixture; and
(iii) adding a predetermined amount of siloxane based oligomeric compound to said resultant mixture followed by optionally mixing a predetermined amount of polyisocyanate under stirring at said second predetermined stirring speed at said second predetermined temperature for said second predetermined time period to obtain the primer composition.
14. The process as claimed in claim 13, wherein said predetermined amount of polyisocyanate is mixed at the time of application.
15. The process as claimed in claim 13, wherein a predetermined amount of an additive is added in step (ii) and (iii); wherein said additive is at least one selected from a plasticizer, a wetting agent, a moisture scavenger and a catalyst.
16. The process as claimed in claim 13, wherein said first predetermined stirring speed is in the range of 200 rpm to 800 rpm; said first predetermined temperature is in the range of 25 ºC to 35 ºC; and said first predetermined time period is in the range of 10 minutes to 15 hours.
17. The process as claimed in claim 13, wherein said second predetermined stirring speed is in the range of 200 rpm to 400 rpm; said second predetermined temperature is in the range of 25 ºC to 35 ºC; and said second predetermined time period is in the range of 10 minutes to 60 minutes.
18. The process as claimed in claims 13 and 15, wherein the predetermined amounts of:
a. said penetration aid is in the range of 30 mass% to 65 mass%;
b. said hydrophobizing agent is in the range of 1 mass% to 5 mass%;
c. said adhesion promoter is in the range of 0.05 mass% to 0.3 mass%;
d. said plasticizer is in the range of 1 mass% to 5 mass%;
e. said wetting agent is in the range of 0.05 mass% to 0.2 mass%;
f. said polymer solution is in the range of 20 mass% to 55 mass%;
g. said siloxane based oligomeric compound is in the range of 1 mass% to 3 mass%;
h. said moisture scavenger is in the range of 0.1 mass% to 0.5 mass%;
i. said catalyst is in the range of 0.05 mass% to 0.5 mass%;
j. said polyisocyanate is in the range of 8 mass% to 12 mass%;
wherein all the mass percentages are with respect to the total mass of the primer composition.
19. The process as claimed in claim 13, wherein the amount of polymer is in the range of 30 mass% to 50 mass% with respect to the total mass of the polymer solution; said polymer is a thermoplastic polymer at least one selected from the group consisting of acrylic polymer, styrene butadiene copolymer, styrene acrylate copolymer, vinyl acrylic copolymer, vinyl ethylene copolymer, vinyl chloride and its copolymer; said predetermined amount of fluid medium is in the range of 50 mass% to 80 mass% with respect to total mass of the polymer solution; and said fluid medium is at least one selected from the group consisting of xylene, toluene, mineral turpentine, cyclobutane, cyclopentane and benzene.
20. The process as claimed in claim 13, wherein said penetration aid is a mixture of a co-wetting solvent and a hydrocarbon solvent; said hydrocarbon solvent is at least one selected from the group consisting of xylene, mineral turpentine, toluene, cyclobutane, cyclopentane and benzene; and said co-wetting solvent is at least one selected from the group consisting of glycol based compound, diacetone alcohol, methyldiacetonalcohol, 4-hydroxy-4-methylhexan-2-one, 4-hydroxy 4-methyl pentonone, and diacetone alcohol water; wherein said glycol based compound is at least one selected from the group consisting of ethylene glycol n-butyl ether (butyl cellosolve), diethylene glycol mono n-butyl ether (butyl carbitol), ethyl carbitol acetate, ethylene glycol mono n-butyl ether acetate, diethylene glycol mono n-butyl ether acetate, and propylene glycol mono methyl ether.
21. The process as claimed in claim 13, wherein said adhesion promoter is a functionalized silane selected from the group consisting of an epoxy functional silane oligomer having a polyfunctional structure bearing gamma-glycidoxy propyl epoxide ring, monomeric organo silane, and oligomeric organo silane.
22. The process as claimed in claim 13, wherein said hydrophobizing agent is at least one selected from the group consisting of stearic acid, oleic acid, rosin acid, zinc stearate, calcium stearate, zinc oleate, and calcium oleate.
23. The process as claimed in claim 13, wherein said siloxane based oligomeric compound is a solvent-less silicone microemulsion concentrate based on silanes and siloxanes (SILRES® BS SMK 1311).
24. The process as claimed in claim 13, wherein said polyisocyanate is a modified hydrophilic polyisocyanate at least one selected from the group consisting of hexamethylene diisocyanate (HDI) based hydrophilic aliphatic polyisocyanate, diphenylmethane-4, 4'-diisocyanate (MDI) based polymeric isocyanate, diphenylmethane-4, 4'-diisocyanate (MDI) based oligomeric isocyanate, toluene diisocyanate, toluene diisocyanate oligomer, isophorone diisocyanate (IPDI) and isophorone diisocyanate oligomer.
25. Use of the primer composition as claimed in claim 1 as an alkali resistant and a durability resistant material, in paint.
Dated this 29th day of March, 2022

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI