Claims:We Claim:

1. Solid particle stabilized copolymer latex comprising Laponite RD clay stabilized co-polymer latex particles with high solid content in the range of 40 to 50% have Tg in the range of 5 °C to 20 °C.

2. Solid particle stabilized copolymer latex as claimed in claim 1 comprising film forming polymer latexes of reduced particle size in the range of 150 to 300 nm.

3. Solid particle stabilized copolymer latex as claimed in anyone of claims 1 or 2 obtained of a pre-emulsion seed having constituents for nucleation and generation of adequate nucleating sites for polymer growth and stabilization said pre-emulsion constituents as seeds variably control the amount of at least partially water soluble monomers going into the process of nucleation for generation of adequate nucleating sites for polymer growth and stabilization also facilitating reduced particle size of solid particle stabilized copolymer latex attained therefrom.

4. Solid particle stabilized copolymer latex as claimed in anyone of claims 1-3 comprising Laponite RD clay stabilized copolymer emulsions selected from styrene-acrylic emulsions, acrylic emulsions favouring improved film formation and pigment packing imparting improved mechanical, thermal and barrier properties to the polymer film.

5. A process for the manufacture of solid particle stabilized copolymer latex as claimed in anyone of claims 1-4 comprising one stage semi-continuous emulsion polymerization process comprising the step of nucleation for generation of adequate nucleating sites for polymer growth and stabilization involving pre-emulsion constituents as seed to variably control the amount of at least partially water soluble monomers going into the process of nucleation for generation of adequate nucleating sites for polymer growth and stabilization also facilitating reduced particle size of solid particle stabilized copolymer latex attained therefrom.

6. A process for the manufacture of solid particle stabilized copolymer latex as claimed in claim 5 in the following steps

i) providing a pre-emulsion comprising selective quantity of Laponite RD clay dispersed in de-ionized water in presence of tetra potassium pyrophosphate (KTPP) followed by addition of monomers under stirring conditions including trace amounts of non-ionic surfactant to stabilize the pre-emulsion;
ii) providing 3-12% of the pre-emulsion of step (i) as seed in the reactor pre-loaded with Laponite RD, KTPP and de-ionized water maintained in the temperature range of 48 °C- 52 °C and increasing the temperature to about 78 °C – 80 °C followed by the addition of buffer, initiator;
iii) polymerizing the mixture of step (ii) above with the polymerization indicated by colour change of the mixture followed by adding the remaining pre-emulsion to the reactor over a period of 3.45 h to 4.15 h;
iv) adding redox couple to the reaction mixture of step (iii) followed by holding the reaction mixture at 80 °C for 45 min to 1 h to polymerize any unreacted monomers followed by addition of the additives after reduction of the reactor temperature to about 40 °C, and obtaining solid particle stabilized copolymer latex comprising Laponite RD clay stabilized copolymer latex therefrom.

7. A process for the manufacture of solid particle stabilized copolymer latex as claimed in anyone of claims 5 or 6 wherein said step (ii) involves providing selective amounts of pre-emulsion together with selective amounts of at least partially water soluble monomers in the range of 0.3 to 0.6 % as seed to facilitate Laponite RD clay stabilized copolymer latex having reduced particle size in the range of 150-300 nm.

8. A process for the manufacture of solid particle stabilized copolymer latex as claimed in anyone of claims 5-7 involving copolymers selected from styrene-acrylic copolymers, acrylic copolymers and monomer to Laponite ratio of 100:1 to 100:2 favoring solid particle stabilized copolymer latex with desired high solid content and reduced particle size.

9. A process for the manufacture of solid particle stabilized copolymer latex as claimed in anyone of claims 5-8 wherein said non-ionic surfactant is selected from alcohol ethoxylate, secondary alcohol ethoxylates, linear fatty alcohol ethoxylates.

10. A process for the manufacture of solid particle stabilized copolymer latex as claimed in anyone of claims 5-9 wherein said monomers include partially water soluble monomers including Butyl acrylate (BA), styrene (ST), methacrylic acid (MAA), 2-ethylhexyl acrylate (EHA), methylmethacrylate (MMA).

Dated this the 5th day of January, 2017 Anjan Sen
Of Anjan Sen and Associates
(Applicants Agent)

, Description:Field of Invention

The present invention provides for solid particle stabilized copolymer latex comprising Laponite RD clay stabilized copolymer latex particles including styrene- acrylic co-polymer latexes as aqueous dispersions and/or emulsions with high solid content and low particle size, and particularly provides, a process for manufacturing such high solid content (solid content 40-50 %) emulsions of low particle size (150-300 nm) and film forming polymer latexes thereof advantageously, with negligible gel content.

Background Art

Emulsion polymerization and stabilization of latex polymer particles by surfactants is a widely accepted technique/method/process. However, the surfactant stabilized polymer latexes are known for poor scrub resistance, dirt pick up resistance, and poor resistance to water absorption due to surfactant migration to the surface through leaching. Solid particles as stabilizing agent for polymer latex are of great use in overcoming those issues. Apart from that, solid particle stabilized emulsion polymers exhibit better mechanical, thermal, and barrier properties to the polymer film.

Emulsion polymerization technique is generally used to prepare such solid particle stabilized emulsion polymers.

CN 103524656 B claims epoxy group-containing styrene-acrylate copolymer having antibacterial properties. Pickering emulsions and their preparation and use where amphiphilic solid particles of titanium dioxide were used as stabilizing agent. These emulsion polymers showed antibacterial properties in interior paint.

CN 103613700 A claims method for preparing polyacrylate/nanometer ZnO composite coating printer binding by using Pickering emulsion polymerization method where a dispersion of nano ZnO with allyoxy nonylphenyl ether sulphate ammonium was prepared which then was added with various monomers to prepare a Pickering emulsion, which then transferred to the reactor. The initiator was added drop wise at 70-75 °C for 2-3 h, after completion of initiator addition, the reaction was held for another 2-3 h. Here the first step involves preparation of ZnO dispersions with APEO based surfactant. Second step involves the emulsion polymerization.

CN 103992421 A claims method for preparing Pickering acrylic polymer emulsion where epoxy modified silica nanoparticles were used as stabilizing agent. Pickering emulsion polymerization was processed by select redox initiation.

CN 104558356 A claims method for synthesizing Pickering-type emulsion through semi- continuous polymerization where the silica nanoparticles along with monomers were dispersed using ultrasonic crusher which then used added drop wise to the reactor.

US 2008/0220176 A1 claims Pickering emulsions, aqueous dispersions of polymeric particles, coatings, and particles networks formed therefrom, where the Pickering emulsion polymers were prepared using solid particles as stabilizing agent however, the solid content of the emulsion polymers are below 40 %. At 40 % solid content emulsion polymer the particle size was 0.42 micron, and in some of their example they have reported particle size of > 1.38 micron even with solid content of 34.2 – 38.3 %.

There are research articles published on solid particles such as SiO2, TiO2, Clay etc. as Pickering stabilizers for polymer of rather low (< 20 %) solid content. An article in Macromol. Rapid Commun. Vol. 31, 1874-1880, 2010 reports the synthesis of Laponite armored styrene-butyl acrylate co-polymer latex of ~ 40 % solid content using macromonomer, methyl ether acrylate terminated poly (ethylene glycol) as a promoter for Laponite and monomer association wherein the resulting polymer particles are approximately 600 nm in diameter as determined by dynamic light scattering technique.

WO 9943495 teaches a coating composition having solids 40-90% and pigment volume concentration (PVC) 5-95%, comprises a latex polymer and hollow particulates. The thick-coverage coatings having fast drying and good tensile, elongation and water resistance, replace traditional coatings used in multi-coat processes or are useful as roof coatings, etc and included Laponite RD but did not relate to any polymerization and stabilization of the polymer latex involving the same.

US7291665 B2 teaches processes for utilizing various emulsion polymerization procedures for preparing aqueous nanocomposite dispersions and mentions the use of polymerizable/ anionic surfactants for core shell polymerization involving 2 step polymerization technique in the presence of at least partially exfoliated, lightly modified clays as well as admixtures of polymer dispersions with at least partially exfoliated, lightly modified clay dispersions.

WO 2014140057 A1 also published as CA2904173A1, CN105189586A, EP2970548A1, US20160024325 discloses use of hybrid water dispersions which can be used in the formation of coating compositions having good blush resistance, abrasion resistance, blister resistance, hardness and scratch resistance and are prepared by mixing a (poly) ethylene (meth) acrylic acid copolymer in water to form a mixture, and reacting the mixture with an organosilane compound.

US7259203B2 teaches processes for utilizing various emulsion polymerization procedures specifically core-shell polymerization which is a two stage polymerization for preparing aqueous nanocomposite dispersions. The disclosed processes include both in-situ polymerizations in the presence of at least partially exfoliated unmodified clays as well as admixtures of polymer dispersions with at least partially exfoliated unmodified clay dispersions wherein the dispersions involved high amount of clay, low solid content and mostly involved admixed copolymer together with clay dispersion.

US6838507 B2 also teaches processes for utilizing various emulsion polymerization procedures for preparing aqueous nanocomposite dispersions. The disclosed processes include in-situ polymerizations and specifically core-shell two stage polymerization involving two stages in the presence of at least partially exfoliated unmodified clays as well as admixtures of polymer dispersions with at least partially exfoliated unmodified clay dispersions involving higher amount of clay low solid content.

As would be apparent from the state of the art discussed above there is a longfelt need in the art for high solid content low particle size copolymer latexes as aqueous dispersions and/or emulsions that would be solid particle stabilized copolymer latex instead of being stabilized by surfactants with negligible gel content that would possess significantly enhanced mechanical, thermal and barrier properties essential for coating applications and would also be manufactured by simple industrial friendly facile emulsion polymerization technique using simple thermal initiators.

Objects of the Invention

The primary object of the present invention is to provide for a high solid content low particle size film forming polymer latexes as aqueous dispersions and/ or emulsions with negligible gel content that are solid particle stabilized copolymer latexes and would possess significantly enhanced mechanical, thermal and barrier properties essential for coating applications.

It is yet another object of the present invention to provide for said solid particle stabilized polymer latexes that would be substantially free of surfactant which would improve the resistance to water absorption due to negligible surfactant migration to the surface through leaching.

It is another object of the present invention to provide for simple industrial friendly facile single stage emulsion polymerization technique using thermal initiators for manufacturing the high solid content low particle size film forming solid particle stabilized polymer latexes with negligible gel content.

Summary of the invention

Thus according to the basic aspect of the present invention there is provided solid particle stabilized copolymer latex comprising Laponite RD clay stabilized co-polymer latex particles with high solid content in the range of 40 to 50% and having Tg in the range of 5 °C to 20 °C.

According to another preferred aspect of the present invention there is provided solid particle stabilized copolymer latex comprising film forming polymer latexes of reduced particle size in the range of 150 to 300 nm.

Advantageously said solid particle stabilized copolymer latex is obtained of a pre-emulsion seed having constituents for nucleation and generation of adequate nucleating sites for polymer growth and stabilization said pre-emulsion constituents as seeds variably control the amount of at least partially water soluble monomers going into the process of nucleation for generation of adequate nucleating sites for polymer growth and stabilization also facilitating reduced particle size of solid particle stabilized copolymer latex attained therefrom.

It was thus surprisingly found by way of the present invention that solid particle stabilized copolymer latex comprising Laponite RD clay stabilized co-polymer latex particles with high solid content in the range of 40 to 50% have Tg in the range of 5 °C to 20 °C could be obtained of a pre-emulsion seed having constituents for nucleation and generation of adequate nucleating sites for polymer growth and stabilization wherein said pre-emulsion constituents as seeds variably control the amount of at least partially water soluble monomers going into the process of nucleation for generation of adequate nucleating sites for polymer growth and stabilization thus also facilitating reduced particle size of solid particle stabilized copolymer latex attained therefrom.
Preferably, said pre-emulsion as seed is employed in amounts of 3-12% in one stage semi-continuous emulsion polymerization process and more preferably upon involving at least some partially water soluble monomers further effectively lowers down the particle size of the solid particle stabilized copolymer latexes.

According to a preferred aspect of the present invention there is provided said solid particle stabilized copolymer latex comprising Laponite RD clay stabilized copolymer emulsions selected from styrene-acrylic emulsions, acrylic emulsions favouring improved film formation and pigment packing imparting improved mechanical, thermal and barrier properties to the polymer film.

According to another aspect of the present invention there is provided a process for the manufacture of said solid particle stabilized copolymer latex comprising one stage semi-continuous emulsion polymerization process comprising the step of nucleation for generation of adequate nucleating sites for polymer growth and stabilization involving pre-emulsion constituents as seed to variably control the amount of at least partially water soluble monomers going into the process of nucleation for generation of adequate nucleating sites for polymer growth and stabilization also facilitating reduced particle size of solid particle stabilized copolymer latex attained therefrom.

Preferably, said process for the manufacture of solid particle stabilized copolymer latex is achieved in the following steps

i) providing a pre-emulsion comprising selective quantity of Laponite RD clay dispersed in de-ionized water in presence of tetra potassium pyrophosphate (KTPP) followed by addition of monomers under stirring conditions including trace amounts of non-ionic surfactant to stabilize the pre-emulsion;
ii) providing 3-12% of the pre-emulsion of step (i) as seed in the reactor pre-loaded with Laponite RD, KTPP and de-ionized water maintained in the temperature range of 48 °C- 52 °C and increasing the temperature to about 78 °C – 80 °C followed by the addition of buffer, initiator;
iii) polymerizing the mixture of step (ii) above with the polymerization indicated by colour change of the mixture followed by adding the remaining pre-emulsion to the reactor over a period of 3.45 h to 4.15 h;
iv) adding redox couple to the reaction mixture of step (iii) followed by holding the reaction mixture at 80 °C for 45 min to 1 h to polymerize any unreacted monomers followed by addition of the additives after reduction of the reactor temperature to about 40 °C, and obtaining solid particle stabilized copolymer latex comprising Laponite RD clay stabilized copolymer latex therefrom.

More preferably, a process for the manufacture of solid particle stabilized copolymer latex is provided wherein said step (ii) involves providing selective amounts of pre-emulsion together with selective amounts of at least partially water soluble monomers in the range of 0.3 to 0.6 % as seed to facilitate Laponite RD clay stabilized copolymer latex having reduced particle size in the range of 150-300 nm.

According to another preferred aspect of the process for said manufacture of solid particle stabilized copolymer latex the same comprises copolymers selected from styrene-acrylic copolymers, acrylic copolymers and monomer to Laponite ratio of 100:1 to 100:2 favoring solid particle stabilized copolymer latex with desired high solid content and reduced particle size.

Preferably, in said process for the manufacture of solid particle stabilized copolymer latex said non-ionic surfactant is selected from alcohol ethoxylate, secondary alcohol ethoxylates, linear fatty alcohol ethoxylates.

More preferably, in said process for the manufacture of solid particle stabilized copolymer latex said monomers include partially water soluble monomers including Butyl acrylate (BA), styrene (ST), methacrylic acid (MAA), 2-ethylhexyl acrylate (EHA), methylmeth acrylate (MMA).

Brief Description of Figures:
Figure 1: Comparison of variation of particle size distribution with various parameters adapted.
Figure 2a: FEGSEM image corresponding to the example 3.
Figure 2b: FEGSEM image corresponding to the example 4.
Figure 3: Comparison of DSC thermogram of surfactant stabilized polymer latex and Laponite RD stabilized polymer latex.

Detailed Description of the Invention

As discussed hereinbefore the present invention provides for solid particle stabilized copolymer latexes comprising Laponite RD clay stabilized copolymer latex particles including styrene-acrylic co-polymer latexes as aqueous dispersions and/ or emulsions with high solid content and low particle size, with significantly improved mechanical, thermal and barrier properties which are essential for coating applications. An industrially facile process for manufacturing such high solid content (solid content of 40-50 %) of low particle size (150-300 nm) and film forming polymer latexes thereof is also provided with negligible gel content.

According to an embodiment of the present invention a process of preparation of stable dispersion of Laponite RD and selected monomers under stirring is provided wherein selective amount of Laponite RD was taken in the reactor instead of surfactant along with initiator and buffer. Selective amount of pre-emulsion as seed was added to the reactor, followed by one stage semi-continuous emulsion co-polymerization by adding the pre-emulsion over a period of 4 h. The dynamic light scattering technique indicated that the particles sizes are in the range of 150-300 nm, and the zeta potential data of ~ -40 mV to -55 mV suggest that, the Laponite RD stabilized co-polymer latex particles are stable against the agglomeration. The FEGSEM images evidenced the spherical shaped latexes of ~ 300 nm in diameter.

According to the process of the present invention a stable aqueous dispersion of Laponite RD clay platelets stabilized monomer droplets was prepared. Known quantity of Laponite RD clay was dispersed in de-ionized water in presence of tetra potassium pyrophosphate (KTPP). Monomers were then added to the dispersion under mechanical stirring at ~ 600 rpm. Trace amount of non-ionic surfactant e.g. alcohol ethoxylate was used to improve the stability of the pre-emulsion.
Known quantity of above prepared pre-emulsion was added as seed to the reactor which was pre-loaded with known amount of Laponite RD, KTPP and de-ionized water at 50 °C. Then the reactor temperature was increased to 80 °C to which known amount buffer, initiator were added. The polymerization was indicated by the appearance of bluish color to the reactor content. The pre-emulsion was added to the reactor over a period of 4 h. After completion of the pre-emulsion addition, known amount of redox couple was added and held the reactor at 80 °C for 1 h to polymerize any unreacted monomers. Ammonia and additives were added once the reactor temperature was reduced to 40 °C.

The control over the latex particle size was achieved by seed quantity which was varied from 3 % to 12 %, and use of partial water soluble monomer methacrylic acid (MAA). In all the cases, the polymerization processing, kettle/stirrer hygiene were good. In some cases, very slight amount of coagulum (<0.15%) was observed. Below examples describe the preparation of Laponite RD stabilized co-polymer latex.
Abbreviations
Laponite RD= Synthetic layered silicate from Rockwood
KTPP= Potassium Tetrapyrophosphate
KPS=Potassium persulphate
SBC=Sodium bicarbonate
TDM=Tertiary dodecyl mercaptan
TBHP=Tertiary-butyl hydroperoxide
SFS=Sodium formaldehyde sulphoxylate
BA=Butyl acrylate
ST=Styrene
MAA=Methacrylic acid
DI water=De-ionized water
Non-ionic surfactant= Alcohol ethoxylate
AMP 95=2-Amino-2-methyl-1-propanol
FEGSEM=Field emission gun scanning electron microscopy

Examples:

Example 1: 40 % solid emulsion latex of larger particle size

The semi-continuous emulsion polymerization process was employed for the preparation of latex. The polymerization was processed in a four necked emulsion reactor equipped with a stirrer, condenser and heating apparatus. Laponite RD (0.05 g) was dispersed in the reactor containing DI water (26.32 g), KTPP (0.1 g), SBC (0.13g) and stirred it for 15-20 min at 200 RPM. The reactor was heated to 50 °C.

The pre-emulsion was prepared by adding Laponite RD (0.6 g) to a solution of DI water (23.03 g) and KTPP (0.4 g) under stirring in a flat bottom flask. After a homogenous solution was observed, BA (16.16 g), ST (21.2 g), MAA (1.2 g), and KPS (0.08 g) was added one after another and stirring was continued for another 20 min. To further improve the stability of the pre-emulsion non-ionic surfactant (0.25 g) was added to it.
A weighed portion of the pre-emulsion (3.145 g, 5 %) was added to the emulsion reactor followed by a solution of KPS (0.15 g) in DI Water (3.18 g). The Temperature was then increased to 80°C. At 80°C a light blue coloration was observed and the remaining portion of the pre-emulsion was fed into the reactor at 80 °C over a period of 4 hrs.
After completion of addition of the pre-emulsion, the flask was flushed with DI water (1.3 g) and it was added to the reactor. Then a solution of TBHP (0.02 g) in DI water (1.05 g) and a solution of SFS (0.02 g) in DI water (1.05 g) were added in said sequence. The temperature was maintained for another 1 h, after 1 h the temperature was reduced to 40 °C. At 40 °C, biocide (0.2 g), AMP 95 (0.7 g) and DI water (2.81 g) was added to it, stirred for 10 minutes and the batch was filtered through nylon mesh.
Approximately 0.15 % of coagulum was observed, and the particles size determined by dynamic light scattering technique was found to be ~ 700 nm, and the particle size distribution is shown in figure 1.

Example 2: 40 % solid emulsion latex of medium particle size

The semi-continuous emulsion polymerization process was employed for the preparation of latex. The polymerization was processed in a four necked emulsion reactor equipped with a stirrer, condenser and heating apparatus. Laponite RD (0.05 g) was dispersed in the reactor containing DI water (24.3 g), KTPP (0.1 g), SBC (0.13 g) and stirred it for 15-20 min at 200 RPM. The reactor was heated to 50 °C.

The pre-emulsion was prepared by adding Laponite RD (0.6 g) to a solution of DI water (23.0 g) and KTPP (0.4 g) under stirring in a flat bottom flask. After a homogenous solution was observed, BA (16.16 g), ST (21.2 g), MAA (1.2 g), TDM (0.03 g) and KPS (0.08 g) was added one after another and stirring was continued for another 20 min. To further improve the stability of the pre-emulsion non-ionic surfactant (0.3 g) was added to it.
A weighed portion of the pre-emulsion (6.297 g, 10 %) was added to the emulsion reactor followed by a solution of KPS (0.15 g) in DI Water (3.15 g). The Temperature was then increased to 80 °C. At 80 °C a light blue coloration was observed and then 14.16 g of pre emulsion was fed over a period of 1 hr. Then a solution of KPS (0.05 g) in de mineralized Water (2.0 g) was added into the reactor. The remaining portion of the pre emulsion was fed into the reactor at 80°C over a period of 3 hrs. After completion of addition of the pre-emulsion, the flask was flushed with DI water (1.3 g) and it was added to the reactor. Then a solution of TBHP (0.02 g) in DI water (1.0 g) and a solution of SFS (0.02 g) in DI water (1.0 g) were added in said sequence. The temperature was maintained for another 1 hr, and then after 1 h the temperature was reduced to 40 C. At 40°C, biocide (0.2 g), AMP 95 (0.7 g) and DI water (2.86 g) was added to it, stirred for 10 minutes and the batch was filtered through nylon mesh. Negligible amount of coagulum was observed, and the particles size determined by dynamic light scattering technique was found to be ~ 500 nm, and the particle size distribution is shown in figure 1.

Example 3: 40 % solid emulsion latex of small particle size

The semi-continuous emulsion polymerization process was employed for the preparation of latex. The polymerization was processed in a four necked emulsion reactor equipped with a stirrer, condenser and heating apparatus. Laponite RD (0.05 g) was dispersed in the reactor containing DI water (26.5 g), KTPP (0.1 g), SBC (0.13 g) and stirred it for 15-20 min 200 RPM. The reactor was heated to 50 °C.

The pre-emulsion was prepared by adding Laponite RD (0.6 g) to a solution of DI water (23.0 g) and KTPP (0.4 g) under stirring in a flat bottom flask. After a homogenous solution was observed, BA (16.16 g), ST (21.2 g), MAA (1.2 g), TDM (0.03 g) and KPS (0.08 g) was added one after another and stirring was continued for another 20 min. To further improve the stability of the pre-emulsion non-ionic surfactant (0.3 g) was added to it.
A weighed portion of the pre-emulsion (6.297 g, 10%) and MAA (0.5 g) was added to the emulsion reactor followed by a solution of KPS (0.15 g) in DI Water (3.0 g). The Temperature was then increased to 80 °C. At 80 °C a light blue coloration was observed. Then the remaining portion of the pre emulsion was fed into the reactor at 80 °C over a period of 4 hrs.
After completion of addition of the pre-emulsion, the flask was flushed with DI water (1.5 g) and it was added to the reactor. Then a solution of TBHP (0.02 g) in DI water (1.0 g) and a solution of SFS (0.02 g) in DI water (1.0 g) were added in said sequence. The temperature was maintained for another 1 hr, and then after 1 h the temperature was reduced to 40 C. At 40 °C, biocide (0.2 g), AMP 95 (0.7 g) and DI water (2.16 g) was added to it, stirred for 10 minutes and the batch was filtered through nylon mesh. Negligible amount of coagulum was observed, and the particles size determined by dynamic light scattering technique was found to be ~ 300 nm, the particle size distribution is shown in figure 1. The FEGSEM images confirm the spherical like particles of ~ 300 nm in diameter as shown in figure 2a.

Example 4: 50 % solid film forming emulsion latex of small particle size

The semi-continuous emulsion polymerization process was employed for the preparation of latex. The polymerization was processed in a four necked emulsion reactor equipped with a stirrer, condenser and heating apparatus. Laponite RD (0.05 g) was dispersed in the reactor containing DI water (18.0 g), KTPP (0.1 g), SBC (0.15 g) and stirred it for 15-20 min at 200 RPM. The reactor was heated to 50 °C.

The pre-emulsion was prepared by adding Laponite RD (0.6 g) to a solution of DI water (21.37 g) and KTPP (0.4 g) under stirring in a flat bottom flask. After a homogenous solution was observed, BA (24.63 g), ST (22.0 g), MAA (2.0 g), TDM (0.03 g) and KPS (0.13 g) was added one after another and stirring was continued for another 20 minutes. To further improve the stability of the pre-emulsion non-ionic surfactant (0.30 g) was added to it.
A weighed portion of the pre-emulsion (7.14 g, 10%) and MAA (0.5 g) was added to the emulsion reactor followed by a solution of KPS (0.2 g) in DI Water (4.0 g). The temperature was then increased to 80 °C. At 80 °C a light blue coloration was observed. Then the remaining portion of the pre-emulsion was fed into the reactor at 80 °C over a period of 4 hrs.
After completion of addition of the pre-emulsion, the flask was flushed with DI water (1.0 g) and it was added to the reactor. Then a solution of TBHP (0.02 g) in DI water (1.0 g) and a solution of SFS (0.02 g) in DI water (1.0 g) were added in said sequence. The temperature was maintained for another 1 hr, after 1 h the temperature was reduced to 40°C. At 40 °C, biocide (0.2 g), AMP 95 (0.7 g) and DI water (1.6 g) was added to it, stirred for 10 minutes and the batch was filtered through nylon mesh.
Negligible amount of coagulum was observed, and the particles size determined by dynamic light scattering technique was found to be ~ 300 nm, the particle size distribution is shown in figure 1. The FEGSEM images confirm the spherical like particles of ~ 300 nm in diameter as shown in figure 2b.

Below the quantity of 3% of said pre-emulsion addition, benefits in achieving the lower particles size is lost and the particles become bigger which benefit was sustainable until 12% and beyond 12% seed addition was found not feasible as it causes highly exothermic reaction, increase in viscosity etc.

The particle size distribution (figure 1) determined by the dynamic light scattering technique showed significant decrease in particle size from example 1 to example 4. The FEGSEM images of example 3 and 4 as shown in figure 2a and 2b evidences the spherical shape particles of ~ 300 nm in size. The differential scanning calorimetric curves evidences the increased thermal behavior as shown in figure 3. It was found that that Tg of Laponite stabilized polymer latex was higher than the surfactant stabilized polymer latex.

It is thus possible by way of the present advancement to provide for solid particle stabilized copolymer latex comprising Laponite RD clay stabilized copolymer latex particles including styrene- acrylic co-polymer latexes as aqueous dispersions and/or emulsions with high solid content and low particle size. A process for providing the same is also provided which is a single stage semi-continuous emulsion polymerization that particularly provides high solid content (solid content 40-50 %) solid particle stabilized copolymer latex as aqueous dispersions/emulsions of low particle size (150-300 nm) and film forming polymer latexes thereof advantageously, with negligible gel content.