WO2023031891A1

WO2023031891A1 - Redispersible polymer powder and a process for its preparation

Info

Publication number: WO2023031891A1
Application number: PCT/IB2022/058326
Authority: WO
Inventors: Srikrushna PATNAIK; Bishwa Ranjan NAYAK; Dhiresh Shashikant GOSALIA
Original assignee: Jesons Industries Limited
Priority date: 2021-09-03
Filing date: 2022-09-05
Publication date: 2023-03-09

Abstract

The present disclosure relates to a redispersible polymer powder and a process for its preparation. The redispersible polymer powder is used to a skim coating composition. The redispersible polymer powder requires less pressure for application. It is suitable for its use in cement dry mix systems such as skim coat, wall care putty, repair mortar, tile adhesive and plasters, water proofing products, and the like. The process for the preparation of the redispersible polymer powder is simple as it does not require high pressure reactors which are typically used in vinyl acetate and ethylene co-polymerization. The skim coating composition prepared by using redispersible polymer powder of the present disclosure is easy to apply; and provides a desired aesthetic look and finish of the final paint.

Description

REDISPERSIBLE POLYMER POWDER AND A PROCESS FOR ITS

PREPARATION

FIELD

The present disclosure relates to a redispersible polymer powder and a process for its preparation. The present disclosure also relates to a skim coating composition by using the redispersible polymer powder.

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 indicates otherwise.

Skim coat: The term “skim coat” refers to a white cement based finishing material, applied over plaster walls and ceiling, to provide an aesthetic appearance (whiteness and smooth surface) to the surface.

Ter-copolymer: The term “ter-copolymer” refers to a chemical compound resulting from a copolymer that has a molecular structure built mostly or completely from a large number of similar units bonded together (such as a complex resin). A ter-copolymer is a result of the copolymerization of at least three different monomers.

Acrylic acid monomer: The term “acrylic acid monomer” refers to acrylic acid having the formula CHD=CHCOOH, which can react with other monomer molecules to form a larger polymer chain or three-dimensional network in a process called polymerization.

BACKGROUND

The background information herein below relates to the present disclosure but is not necessarily prior art.

The white appearance of the wall is highly desirable in order to get the true colour tone of the applied paint. Skim coat is an additional layer on a plastered wall surfaces, which is usually a thin layer of 1 to 1.5 mm thickness. It provides the desired aesthetic look and finish of the final paint, and improves the subsequent applicability of the paint and distemper over it. To the skim coat, in addition to the white cement and the lime stone, polymers are generally added. The polymers improve the properties of skim coat such as adhesion, workability, flexibility and water resistance. Such polymers are usually added in a powdered form, wherein these polymer powders is required to be easily redispersed in water to form a paste. This redispersible polymer powder allows the skim coat to generate the smoothness of the wall surface.

The polymer powder used in the skim coat composition is generally based on vinyl acetate and ethylene (VAE) polymers. The VAE polymers are prepared from ethylene and vinyl acetate as a comonomer. Ethylene does not undergo hydrolysis in water when used in the vinyl acetate copolymer system, and being a flexible monomer also provides a characteristic of impact resistance to skim coat when applied on the plastered surface. The various grades of VAE polymers having different chain lengths of ethylene are available in the market that fulfil the characteristic requirement for multiple applications such as skim coat, tile adhesive, repair mortar, plaster, water-proofing products and the like.

However, ethylene monomer, besides its tremendous attributes, is not easy to handle because of its gaseous nature. In the polymerization process, very stringent conditions are required for converting the ethylene monomers from the gaseous state to liquid state. The polymerization process requires high pressure reactors to achieve the complete polymerization. The pressure reactors are not easy to operate at a commercial scale production.

Further, the VAE polymers being widely used for cement based dry mix system and are in high demand, therefore meeting the cost requirement is a great challenge.

Therefore, there is felt a need for an alternative polymer powder that mitigates the drawbacks mentioned herein above.

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 redispersible polymer powder. Still another object of the present disclosure is to provide a process for the preparation of a redispersible polymer powder.

Yet another object of the present disclosure is to provide a redispersible polymer powder used in the preparation of skim coating composition.

Another object of the present disclosure is to provide a redispersible polymer powder that is suitable component for tile adhesive, repair mortar, plaster, cement based dry mix system, and water proofing products.

Yet another object of the present disclosure is to provide a skim coating 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 provides a redispersible polymer powder. The redispersible polymer powder comprises a homogeneous mixture of a ter-copolymer, a protective colloid and an anti-caking agent. The ter-copolymer comprises 75 mass% to 85 mass% of a first vinyl ester monomer with respect to the total mass of the ter-copolymer, 5 mass% to 15 mass% of at least one acrylate monomer with respect to the total mass of the ter-copolymer, 0 mass% to 5 mass% of acrylic acid monomer with respect to the total mass of the ter-copolymer; and 0 mass% to 10 mass% of at least one second vinyl ester monomer with respect to the total mass of the ter-copolymer. The protective colloid is present in an amount in the range of 10 mass% to 20 mass% with respect to the total mass of the redispersible polymer powder. The anticaking agent is present in an amount in the range of 5 mass% to 15 mass% with respect to the total mass of the redispersible polymer powder.

The present disclosure further provides a process for the preparation of redispersible polymer powder. In a reactor, predetermined amounts of a first vinyl ester monomer, at least one acrylate monomer, optionally an acrylic acid monomer, optionally at least one second vinyl ester monomer, and at least one first protective colloid are reacted in the presence of a redox catalyst and water at a first predetermined temperature for a first predetermined time period at atmospheric pressure to obtain a reaction mixture comprising a ter-copolymer. The reaction mixture is cooled to a second predetermined temperature to obtain a ter-copolymer emulsion. The ter-copolymer emulsion is blended with predetermined amounts of at least one second protective colloid and an anti-caking agent for a second predetermined time period to obtain a suspension. The suspension is spray dried at a predetermined inlet temperature and a predetermined outlet temperature at a predetermined predetermined flow rate to obtain the redispersible polymer powder.

The present disclosure still further provides a skim coating composition. The skim coating composition comprises 1 mass% to 3 mass% of the redispersible polymer powder, 0.2 mass% to 0.6 mass% of an additive, 10 mass% to 20 mass% of a binder, and 75 mass% to 90 mass% of a filler. All the mass percentages are with respect to the total mass of the skim coating composition.

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.

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.

Conventionally, vinyl acetate copolymers with ethylene as comonomer have been widely used in skim coating composition because of better adhesion, flexibility and water resistance property. Ethylene being extensively used as a comonomer to fulfill the performance of flexibility and water resistance property in various composition. However, handling of the gaseous ethylene monomer is tedious. Further, the process of copolymerization of vinyl acetate and ethylene requires a high pressure reactor.

In an aspect, the present disclosure provides a redispersible polymer powder. The redispersible polymer powder comprises a homogeneous mixture of a ter-copolymer, a protective colloid and an anti-caking agent.

The ter-copolymer comprises a first vinyl ester monomer, at least one acrylate monomer, an acrylic acid monomer and at least one second vinyl ester monomer.

In accordance with an embodiment of the present disclosure, the ter-copolymer comprises a first vinyl ester monomer, at least one acrylate monomer and an acrylic acid monomer. In accordance with another embodiment of the present disclosure, the ter-copolymer comprises a first vinyl ester monomer, at least one acrylate monomer and at least one second vinyl ester monomer. In accordance with still another embodiment of the present disclosure, the ter- copolymer comprises a first vinyl ester monomer, an acrylic acid monomer, at least one acrylate monomer and at least one second vinyl ester monomer.

In accordance with the present disclosure, the first vinyl ester monomer is vinyl acetate.

In accordance with the present disclosure, the first vinyl ester monomer is present in an amount in the range of 75 mass% to 85 mass% with respect to the total mass of the ter- copolymer. In an embodiment, the first vinyl ester monomer is present in an amount of 84.5 mass% with respect to the total mass of the ter-copolymer. In another embodiment, the first vinyl ester monomer is present in an amount of 76.2 mass% with respect to the total mass of the ter-copolymer. In still another embodiment, the first vinyl ester monomer is present in an amount of 80 mass% with respect to the total mass of the ter-copolymer. The hardness of the redispersible polymer powder increases with the increasing amount of first vinyl ester monomer. A suitable amount can be utilized as per the requirement.

In accordance with the present disclosure, the acrylate monomer is at least one selected from butyl acrylate and methacrylate. In an embodiment, the acrylate monomer is butyl acrylate. In another embodiment, the acrylate monomer is methacrylate.

In accordance with the present disclosure, the acrylate monomer is present in an amount in the range of 5 mass% to 15 mass% of with respect to the total mass of the ter-copolymer. In an embodiment, the acrylate monomer is present in an amount of 12.5 mass% with respect to the total mass of the ter-copolymer. In another embodiment, the acrylate monomer is present in an amount of 10.8 mass% with respect to the total mass of the ter-copolymer. In still another embodiment, the acrylate monmer is present in an amount of 14.5 mass% with respect to the total mass of the ter-copolymer. In yet another embodiment, the acrylate monomer is present in an amount of 5.5 mass% with respect to the total mass of the ter- copolymer.

The acrylate monomer can serve the purpose of flexibility to a skim coat/putty. The flexibility of the redispersible polymer powder increases with the increasing amount of butyl acrylate monomer. A suitable amount can be utilized as per the requirement.

In accordance with the present disclosure, the acrylic acid monomer is present in an amount is the range of 0 mass% to 5 mass% with respect to the total mass of the ter-copolymer. In an embodiment, the acrylic acid monomer is present in an amount of 3 mass% with respect to the total mass of the ter-copolymer. In another embodiment, the acrylic acid monomer is present in an amount of 4.9 mass% with respect to the total mass of the ter-copolymer.

In accordance with the present disclosure, the at least one second vinyl ester monomer is at least one selected from the group consisting of versatic acid 9 vinyl ester, vinyl versatate, vinyl neodecanoate and 2-ethyl hexanoic acid vinyl ester. In an embodiment, the at least one second vinyl ester monomer is vinyl versatate. In another embodiment, the at least one second vinyl ester monomer is versatic acid 9 vinyl ester. In still another embodiment, the at least one second vinyl ester monomer is vinyl neodecanoate. In yet another embodiment, the at least one second vinyl ester monomer is 2-ethyl hexanoic acid vinyl ester.

In accordance with the present disclosure, the at least one second vinyl ester monomer is present in an amount in the range of 0 mass% to 10 mass% of with respect to the total mass of the ter-copolymer. In an embodiment, the at least one second vinyl ester monomer is present in an amount of 5 mass% with respect to the total mass of the ter-copolymer. In another embodiment, the at least one second vinyl ester monomer is present in an amount of 9.5 mass% with respect to the total mass of the ter-copolymer. In still another embodiment, the at least one second vinyl ester monomer is present in an amount of 7.5 mass% with respect to the total mass of the ter-copolymer.

The second vinyl ester monomer provides hydrophobicity/water resistance to the skim coat. The second vinyl ester monomer can also protect other co-monomers in the powder with respect to hydrolytic stability by providing an umbrella shaped structure in the powder. Due to long chain monomer, the second vinyl ester monomer provides alkali resistance property to the polymer like an umbrella which protects from the rain.

The hydrophobicity, adhesion and alkali resistance of the redispersible polymer powder increases with an increasing amount of the second vinyl ester monomer. A suitable amount can be utilized as per the requirement.

In accordance with the present disclosure, the protective colloid is selected from the group consisting of polyvinyl alcohol, alkyl hydroxyl ethyl cellulose and glycols. In an embodiment, the protective colloid is polyvinyl alcohol. In another embodiment, the protective colloid is alkyl hydroxyl ethyl cellulose. In still another embodiment, the protective colloid is a glycol.

In accordance with the present disclosure, the glycols are selected from the group consisting of ethylene glycol, diethylene glycol, propylene glycol, ethylene glycol monobutyl ether (EGBE), and ethylene glycol monomethyl ether (EGME).

In accordance with the present disclosure, the protective colloid is present in an amount in the range of 10 mass% to 20 mass% with respect to the total mass of the redispersible polymer powder. In an embodiment, the protective colloid is present in an amount of 15 mass% with respect to the total mass of the redispersible polymer powder. In another embodiment, the protective colloid is present in an amount of 11 mass% with respect to the total mass of the redispersible polymer powder. In still another embodiment, the protective colloid is present in an amount of 17 mass% with respect to the total mass of the redispersible polymer powder. In yet another embodiment, the protective colloid is present in an amount of 19.5 mass% with respect to the total mass of the redispersible polymer powder. In accordance with the present disclosure, the anti-caking agent is selected from the group consisting of domomite, silica, calcium carbonate, magnesium carbonate and clay. In an embodiment, the anti-caking agent is dolomite. In another embodiment, the anti-caking agent is calcium carbonate. In still another embodiment, the anti-caking agent is magnesium carbonate. In yet another embodiment, the anti-caking agent is clay. In still another embodiment, the anti-caking agent is silica.

In accordance with the present disclosure, the anti-caking agent is present in an amount in the range of 5 mass% to 15 mass% with respect to the total mass of the redispersible polymer powder. In an embodiment, the anti-caking agent is present in an amount of 10 mass% with respect to the total mass of the redispersible polymer powder. In another embodiment, the anti-caking agent is present in an amount of 6 mass% with respect to the total mass of the redispersible polymer powder. In still another embodiment, the anti-caking agent is present in an amount of 5 mass% with respect to the total mass of the redispersible polymer powder.

The redispersible polymer powder has a moisture content in the range of 1% to 2%. In an exemplary embodiment, the redispersible polymer powder has a moisture content of 1.5%.

The redispersible polymer powder of the present disclosure has the desired flow property for easy application. The redispersible polymer powder of the present disclosure can be redispersed in water when agitated to obtain a paste.

The redispersible polymer powder of the present disclosure can be stored in an airtight bag to keep it water-proof. The redispersible polymer powder of the present disclosure can have shelf life of at least one year in the absence of moisture, sunlight and external pressure.

The redispersible polymer powder of the present disclosure can particularly be useful in skim coat application or wall putty, and provide performance equivalent or comparable to VAE based polymer powder with respect to chalking, tensile adhesion and water resistance properties.

The redispersible polymer powder of the present disclosure has comparatively low production cost as compared to that of the VAE based polymer powders. The redispersible polymer powder of the present disclosure is suitable for its use such as cement dry mix systems, wall care putty, repair mortar, tile adhesive and plasters, water proofing products and the like. The use of the acrylic acid monomer, the acrylate monomer and/or the second vinyl ester monomer instead of ethylene monomer provide comparable flexibility performance and hydrophobicity/water resistance properties, which are required in cement based dry mix system and specially for skim coat application.

The redispersible polymer powder of the present disclosure when used to make skim coat or putty are easy to apply, as it requires less pressure. The redispersible polymer powder of the present disclosure is easy to handle and transport.

The redispersible polymer powder of the present disclosure allow the skim coat to retain the smoothness of the wall surface even at extreme temperature conditions. The redispersible polymer powder of the present disclosure provides the desired aesthetic look and finish of the final paint.

In another aspect, the present disclosure provides a process for the preparation of redispersible polymer powder.

The process is decribed in detail:

In a reactor, predetermined amounts of a first vinyl acetate monomer, at least one acrylate monomer, optionally an acrylic acid and optionally at least one second vinyl ester monomer, and at least one first protective colloid are reacted in the presence of a redox catalyst and water at a predetermined temperature for a first predetermined time period at atmospheric pressure to obtain a reaction mixture comprising a ter-copolymer.

In accordance with the present disclosure, the first vinyl ester monomer is present in an amount in the range of 75 mass% to 85 mass% with respect to the total mass of the ter- copolymer. In an embodiment, the first vinyl ester monomer is present in an amount of 84.5 mass% with respect to the total mass of the ter-copolymer. In another embodiment, the first vinyl ester monomer is present in an amount of 76.2 mass% with respect to the total mass of the ter-copolymer. In still another embodiment, the first vinyl ester monomer is present in an amount of 80 mass% with respect to the total mass of the ter-copolymer.

In accordance with the present disclosure, the first vinyl ester monomer is vinyl acetate. In accordance with the present disclosure, the acrylate monomer is at least one selected from butyl acrylate and methacrylate. In an embodiment, the acrylate monomer is butyl acrylate. In another embodiment, the acrylate monomer is methacrylate.

In accordance with the present disclosure, the acrylate monomer is present in an amount in the range of 5 mass% to 15 mass% with respect to the total mass of the ter-copolymer. In an embodiment, the acrylate monomer is present in an amount of 12.5 mass% with respect to the total mass of the ter-copolymer. In another embodiment, the acrylate monomer is present in an amount of 10.8 mass% with respect to the total mass of the ter-copolymer. In still another embodiment, the acrylate monmer is present in an amount of 14.5 mass% with respect to the total mass of the ter-copolymer. In yet another embodiment, the acrylate monomer is present in an amount of 5.5 mass% with respect to the total mass of the ter-copolymer.

In accordance with the present disclosure, the at least one second vinyl ester monomer is present in an amount in the range of 0 mass% to 10 mass% of with respect to the total mass of the ter-copolymer. In an embodiment, the at least one second vinyl ester monomer is present in an amount of 5 mass% with respect to the total mass of the ter-copolymer. In another embodiment, the at least one second vinyl ester monomer is present in an amount of 9.5 mass% with respect to the total mass of the ter-copolymer. In still another embodiment, the at least one second vinyl ester monomer is present in an amount of 7.5 mass% with respect to the total mass of the ter-copolymer. In accordance with the present disclosure, the first protective colloid is present in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the redispersible polymer powder.

In accordance with the present disclosure, the redox catalyst is selected from the group consisting of tertiary butyl hydroperoxide, sodium formaldehyde sulphoxylated, hydrogen peroxide and tartaric acid. In an embodiment, the redox catalyst is tertiary butyl hydroperoxide. In another embodiment, the redox catalyst is sodium formaldehyde sulphoxylated. In still another embodiment, the redox catalyst is hydrogen peroxide. In yet another embodiment, the redox catalyst is tartaric acid.

In accordance with the present disclosure, the redox catalyst is present in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the ter-copolymer. In an embodiment, the redox catalyst is present in an amount of 5.2 mass% with respect to the total mass of the ter-copolymer. In another embodiment, the redox catalyst is present in an amount of 7 mass% with respect to the total mass of the ter-copolymer. In still another embodiment, the redox catalyst is present in an amount of 9.5 mass% with respect to the total mass of the ter-copolymer.

In accordance with the present disclosure, the first predetermined temperature is in the range of 45 °C to 70 °C. In an embodiment, the first predetermined temperature is 50 °C. In another embodiment, the first predetermined temperature is 65 °C.

In accordance with the present disclosure, the first predetermined time period is in the range of 8 hours to 14 hours. In an embodiment, the first predetermined time period is 12 hours.

The reaction mixture is cooled to a second predetermined temperature to obtain a ter- copolymer emulsion.

In accordance with the present disclosure, the second predetermined temperature is in the range of 22 °C to 30 °C. In an exemplary embodiment, the second predetermined temperature is 25 °C.

The ter-copolymer emulsion is blended with predetermined amounts of at least one second protective colloid and an anti-caking agent for a second predetermined time period to obtain a suspension. In accordance with the present disclosure, the first protective colloid and the second protective colloid are same or different and are independently selected from the group consisting of polyvinyl alcohol, alkyl hydroxyl ethyl cellulose and glycols. In an embodiment, the first protective colloid and the second protective colloid are polyvinyl alcohol. In an embodiment, the first protective colloid and the second protective colloid is polyvinyl alcohol. In another embodiment, the first protective colloid and the second protective colloid is alkyl hydroxyl ethyl cellulose. In still another embodiment, the first protective colloid and the second protective colloid is glycol. In yet another example, the first protective colloid is polyvinyl alcohol and the second protective colloid is alkyl hydroxyl ethyl cellulose. In still another example, the first protective colloid is polyvinyl alcohol and the second protective colloid is a glycol. In yet another embodiment, the second protective colloid is 19% of polyvinyl alcohol solution.

In accordance with the present disclosure, the second protective colloid is present in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the redispersible polymer powder.

In accordance with the present disclosure, the anti-caking agent is selected from the group consisting of domomite, silica, calcium carbonate, magnesium carbonate and clay. In an embodiment, the anti-caking agent is dolomite. In another embodiment, the anti-caking agent is calcium carbonate. In still another embodiment, the anti-caking agent is magnesium carbonate. In yet another embodiment, the anti-caking agent is clay. In still another embodiment, the anti-caking agent is silica.

The suspension is spray dryed at a predetermined inlet temperature and a predetermined outlet temperature at a predetermined flow rate to obtain the redispersible polymer powder. In accordance with the present disclosure, the predetermined inlet temperature is in the range of 160 °C to 170 °C. In an embodiment, the predetermined inlet temperature is 165 °C.

In accordance with the present disclosure, the predetermined outlet temperature is in the range of 85 °C to 95 °C. In an embodiment, the predetermined outlet temperature is 90 °C.

In accordance with the present disclosure, the predetermined flow rate is in the range of 95 kg/hour to 105 kg/hour. In an embodiment, the predetermined flow rate is 100 kg/hour.

The process for the preparation of the redispersible polymer powder of the present disclosure can be performed in any atmospheric stirred type reactor having a jacket and a condenser.

The process for the preparation of the redispersible polymer powder of the present disclosure does not utilize any surfactant.

The process for the preparation of the redispersible polymer powder of the present disclosure is simpler than conventional high pressure emulsion polymerization process.

The process of the present disclosure does not require a high pressure reactor typically used in vinyl acetate and ethylene copolymerization process, thereby making the process simpler and hence economic.

The process of the present disclosure provides an opportunity to overcome the tedious handling of gaseous ethylene monomer during the polymerization process.

The process for the preparation of the redispersible polymer powder of the present disclosure is cost effective.

In still another aspect, the present disclosure provides a skim coating composition. The skim coating composition comprises the redispersible polymer powder of the present disclosure, an additive, a binder, and a filler.

In accordance with the present disclosure, the redispersible polymer powder is present in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the skim coating composition. In an embodiment, the redispersible polymer powder is present in an amount of 2 mass% with respect to the total mass of the skim coating composition. In accordance with the present disclosure, the additive is selected from the group consisting of cellulose ether and methyl hydroxyl ethyl cellulose. In an exemplary embodiment, the additive is methyl hydroxyl ethyl cellulose.

In accordance with the present disclosure, the additive is present in an amount in the range of 0.2 mass% to 0.6 mass% with respect to the total mass of the skim coating composition. In an exemplary embodiment, the additive is present in an amount of 0.4 mass% with respect to the total mass of the skim coating composition.

In accordance with the present disclosure, the binder is white cement.

In accordance with the present disclosure, the binder is present in an amount in the range of 10 mass% to 20 mass% with respect to the total mass of the skim coating composition. In an exemplary embodiment, the binder is present in an amount of 15 mass% with respect to the total mass of the skim coating composition.

In accordance with the present disclosure, the filler is selected from the group consisting of domomite, silica, calcium carbonate, magnesium carbonate and clay. In an exemplary embodiment, the filler is dolomite.

In accordance with the present disclosure, the filler is present in an amount in the range of 75 mass% to 90 mass% with respect to the total mass of the skim coating composition. In an exemplary embodiment, the filler is present in an amount of 83 mass% with respect to the total mass of the skim coating composition.

The skim coating composition of the present disclosure is easy to apply, as it requires less pressure when used as a skim coat or a putty.

The skim coating composition of the present disclosure provides the desired aesthetic look and finish of the final 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 tested to scale up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.

EXPERIMENTAL DETAILS:

Process for the preparation of the redispersible polymer powder in accordance with the present disclosure

In a reactor, vinyl acetate monomer (a first vinyl ester monomer), acrylate monomer, optionally acrylic acid monomer, optionally a second vinyl ester monomer and a first protective colloid were reacted in the presence of 7 g of tertiary butyl hydroperoxide (redox catalyst) and 100 g water at 50 °C for 11 hours at atmospheric pressure to obtain a reaction mixture comprising a ter-copolymer. The reaction mixture was cooled to 25 °C to obtain a ter-copolymer emulsion. The ter-copolymer emulsion was blended with a second protective colloid and an anti-caking agent for 3 hours to obtain a suspension. The suspension was spray dried to obtain the redispersible polymer powder. The inlet temperature of the spray drier was 165 °C and outlet temperature of the spray drier was 90 °C. The spray drying was continuously performed at a flow rate of 100 kg/hours. The amounts of each component is provided in table 1.

Table 1 Components used in the preparation of resdispersible polymer powder in accordance with the present disclosure

*mass percentage with respect to the total mass of the ter-copolymer; **mass percentage with respect to the total mass of the redispersible polymer powder.

Skim coating composition/wall putty in accordance with the present disclosure

Skim coating compositions of the present disclosure are illustrated in Table 2. Table 2 Skim coating compositions in accordance with the present disclosure

40 gm of water was mixed in 100 g of powdered skim coating composition of the present disclosure, which was suitable for application on a surface, and characterized further as shown in Table 3. Table 3 Properties of skim coating composition in accordance with the present disclosure

The skim coating composition of the present disclosure provide performance equivalent or comparable to VAE based polymer powder with respect to chalking, tensile adhesion and water resistance properties. TECHNICAL ADVANCEMENTS

The present disclosure described hereinabove has several technical advantages including, but not limited to, the realization of a redisperible polymer powder that: is easy to apply as it requires less pressure when used as a skim coat or putty; has low production cost as compared to that of the VAE based polymer powder; is easy to handle and transport; • allows the skim coat to retain the smoothness of the wall surface, even at extreme temperature conditions; and

• provide a desired aesthetic look and finish of the final paint; a process for the preparation of the redispersible polymer powder that:

• does not involve tedious handing of the gaseous ethylene monomer; and

• is simple as it does not require high pressure reactors which are typically used in vinyl acetate and ethylene co-polymerization; and a skim coating composition that:

• is easy to apply;

• provide desired performance with respect to chalking, tensile adhesion and water resistance properties; and

• provides a desired aesthetic look and finish of the final paint.

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

CLAIMS:

1) A redispersible polymer powder comprising a homogeneous mixture of: a. a ter-copolymer comprising: i. 75 mass% to 85 mass% of a first vinyl ester monomer with respect to the total mass of the ter-copolymer; ii. 5 mass% to 15 mass% of at least one acrylate monomer with respect to the total mass of the ter-copolymer; iii. 0 mass% to 5 mass% of acrylic acid monomer with respect to the total mass of the ter-copolymer; and iv. 0 mass% to 10 mass% of at least one second vinyl ester monomer with respect to the total mass of the ter-copolymer; b. 10 mass% to 20 mass% of a protective colloid with respect to the total mass of the redispersible polymer powder; and c. 5 mass% to 15 mass% of an anti-caking agent with respect to the total mass of the redispersible polymer powder.

2) The redispersible polymer powder as claimed in claim 1, wherein said redispersible polymer powder is characterized by having a moisture content in the range of 1 % to 2%.

3) The redispersible polymer powder as claimed in claim 1 , wherein said first vinyl ester monomer is vinyl acetate; and said acrylate monomer is at least one selected from butyl acrylate and methacrylate.

4) The redispersible polymer powder as claimed in claim 1, wherein said second vinyl ester monomer is at least one selected from the group consisting of versatic acid 9 vinyl ester, vinyl versatate, vinyl neodecanoate and 2-ethyl hexanoic acid vinyl ester.

5) The redispersible polymer powder as claimed in claim 1, wherein said protective colloid is at least one selected from the group consisting of polyvinyl alcohol, alkyl hydroxy ethyl cellulose, and glycols; and said anti-caking agent is at least one selected from the group consisting of domomite, silica, calcium carbonate, magnesium carbonate and clay.

6) A process for the preparation of redispersible polymer powder, said process comprising the following steps:

(i) reacting, in a reactor, predetermined amounts of a first vinyl ester monomer, at least one acrylate monomer, optionally an acrylic acid monomer, optionally at least one second vinyl ester monomer, and at least one first protective colloid in the presence of a redox catalyst and water at a first predetermined temperature for a first predetermined time period at atmospheric pressure to obtain a reaction mixture comprising a ter-copolymer;

(ii) cooling said reaction mixture to a second predetermined temperature to obtain a ter-copolymer emulsion;

(iii) blending said ter-copolymer emulsion with predetermined amounts of at least one second protective colloid and an anti-caking agent for a second predetermined time period to obtain a suspension; and

(iv) spray drying said suspension at a predetermined inlet temperature and a predetermined outlet temperature at a predetermined flow rate to obtain the redispersible polymer powder. ) The process as claimed in claim 6, wherein said first vinyl ester monomer is vinyl acetate; said acrylate monomer is at least one selected from butyl acrylate and methacrylate; and said second vinyl ester monomer is at least one selected from the group consisting of versatic acid 9 vinyl ester, vinyl versatate, vinyl neodecanoate and 2-ethyl hexanoic acid vinyl ester. ) The process as claimed in claim 6, wherein said redox catalyst is selected from the group consisting of tertiary butyl hydroperoxide, sodium formaldehyde sulphoxylated, hydrogen peroxide and tartaric acid. ) The process as claimed in claim 6, wherein said first protective colloid and said second protective colloid are same or different and are independently selected from the group consisting of polyvinyl alcohol, alkyl hydroxyl ethyl cellulose, and glycols. 0) The process as claimed in claim 6, wherein said first predetermined temperature is in the range of 45 °C to 70 °C; said first predetermined time period is in the range of 8 hours to 14 hours; said second predetermined temperature is in the range of 22 °C to 30 °C; said second predetermined time period is in the range of 1 hours to 5 hours; said predetermined inlet temperature is in the range of 160 °C to 170 °C; said predetermined outlet temperature is in the range of 85 °C to 95 °C; and said predetermined flow rate is in the range of 95 kg/hour to 105 kg/hour. 1) The process as claimed in claim 6, wherein

• said first vinyl ester monomer is present in an amount in the range of 75 mass% to 85mass% with respect to the total mass of the ter-copolymer; • said acrylate monomer is present in an amount in the range of 5 mass% to 15 mass% with respect to the total mass of the ter-copolymer;

• said acrylic acid monomer is present in an amount in the range of 0 mass% to 5 mass% with respect to the total mass of the ter-copolymer;

• said second vinyl ester monomer is present in an amount in the range of 0 mass% to 10 mass% with respect to the total mass of the ter-copolymer;

• said redox catalyst is present in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the ter-copolymer;

• said first protective colloid is present in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the redispersible polymer powder;

• said second protective colloid is present in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the redispersible polymer powder; and

• said anti-caking agent is present in an amount in the range of 5 mass% to 15 mass% with respect to the total mass of the redispersible polymer powder.) A skim coating composition comprising a. 1 mass% to 3 mass% of the redispersible polymer powder as claimed in claim 1; b. 0.2 mass% to 0.6 mass% of an additive; c. 10 mass% to 20 mass% of a binder; and d. 75 mass% to 90 mass% of a filler; wherein all the mass percentages are with respect to the total mass of the skim coating composition. ) The skim coating composition as claimed in claim 12, wherein said additive is selected from the group consisting of cellulose ether and methyl hydroxyl ethyl cellulose; said filler is selected from the group consisting of domomite, silica, magnesium carbonate and clay; and said binder is white cement.