DESC:FIELD OF THE INVENTION
[0001] The present disclosure is related to the alkali soluble resins (ASRs) and methods of preparation thereof. The present disclosure also relates to provide an emulsion polymer with core-shell structure and method of preparation thereof.

BACKGROUND OF THE INVENTION
[0002] Background description includes information that may be useful in understanding the present invention. It is not an admission that any of the information provided herein is prior art or relevant to the presently claimed invention, or that any publication specifically or implicitly referenced is prior art.
[0003] Acrylic acid is the one of key monomers for the production of various low and high molecular weight polymers. Low molecular weight acrylic acid based copolymers/resins are widely used in waterborne coatings and ink industry as a pigment dispersion, emulsifier, sizing agent in paper industry and over print varnishes (OPV) for gloss improvement applications. These specialty resins are often called as alkali soluble resins (ASRs) because of its solubility in aqueous alkali media. ASR is a copolymer, often prepared in solution polymerization at high temperature conditions (200-270°C). While in the solution polymerization the molecular weight of resultant ASR is easily controllable, removing solvent from the resin (ASR) and recycling of the solvent is troublesome and not preferable from economics point of view. In bulk polymerization, for controlling the molecular weight of the resultant ASR, usage of chain transfer agent increases the cost of production of ASR.
[0004] Conventional emulsion polymerization [Hu et al., Eur. Polym. J., 2008, 44, 2695-2701; Müller et al., Macromolecules, 1997, 30, 2288–2293; Lee et al. Micromol. Symp, 2000, 151, 479-485] exhibited the disadvantages such as the large use of small molecular surfactants pollute the environment and limit the finishing materials properties such as the freezing stability, the mechanical stability, the wet and dry rubbing resistance, issue of corrosion and so on. In order to avoid these disadvantages, the polymeric surfactants such as ASR was applied to the emulsion polymerization.
[0005] In view of the above, there is a long felt need to develop an economical process for production of novel alkali soluble resins (ASRs) that exhibits improved properties. There is also need for the development of an efficient process for production of emulsion polymer with core-shell structure that exhibit improved properties.

OBJECTIVES OF THE INVENTION
[0006] An objective of the present disclosure is to provide an alkali soluble resin (ASR).
[0007] Another objective of the present disclosure is to provide a process for preparation of an Alkali Soluble Resin (ASR).
[0008] Another objective of the present disclosure is to provide an emulsion polymer with core-shell structure.
[0009] Another objective of the present disclosure is to provide a process for preparation of an emulsion polymer with core-shell structure.

SUMMARYOF THE INVENTION
[0010] This summary is provided to introduce a selection of concepts in a simplified form that are further described below in detailed description section. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used as an aid in determining the scope of the claimed subject matter.
[0011] Aspects of the present disclosure is to provide an alkali soluble resin (ASR) having (a) an acrylic acid dimer as a first co-monomer; and (b) a second co-monomer selected from any or a combination of acrylic acid based monomer, styrene based monomer and maleic anhydride based monomer.
[0012] Aspects of the present disclosure is to provide a process for preparation of an Alkali Soluble Resin (ASR) having (a) taking an acrylic acid dimer as a first co-monomer; (b) taking a second co-monomer selected from any or a combination of acrylic acid based monomer, styrene based monomer and maleic anhydride based monomer; and (c) effecting polymerization between said first co-monomer and said second co-monomer in the present of a solvent or without solvent to obtain the Alkali Soluble Resin (ASR).
[0013] Aspects of the present disclosure is to provide an emulsion polymers with core-shell structure having 7 to 15 % w/w of an alkali soluble resin (ASR) of the total wt. of the emulsion; 0.5 to 1.5 % w/w of an ammonia solution of the total wt. of the emulsion; 20 to 35 % w/w of a monomer system of the total wt. of the emulsion; 0.2 to 1.2 % w/w of a first initiator of the total wt. of the emulsion; and 0.03 to 0.15 % w/w of a second initiator of the total wt. of the emulsion.
[0014] Aspects of the present disclosure is to provide a process for preparation of an emulsion polymers with core-shell structure having (a) preparing a solution of an acrylic acid dimer based Alkali Soluble Resin (ASR); (b) reacting the solution of the acrylic acid dimer based Alkali Soluble Resin (ASR) with a monomer system in presence of a first initiator for a period ranging from 30 minutes to 120 minutes to obtain a polymeric mixture; and (c) effecting post-polymerization of the polymeric mixture in presence of a second initiator to obtain the emulsion polymer with core-shell structure.
[0015] Other aspects of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learnt by the practice of the invention.

BRIEF DISCRIPTION OF THE DRAWINGS
[0016] Figure 1 illustrates viscosity, solid content vs dimer percentage effect on core-shell emulsions.
[0017] Figure 2 illustrates viscoelastic measurement of ASR emulsion prepared from D0= glacial acrylic acid, D10 = dimer content is 10%, D20 = dimer content is 20%, D30 = dimer content is 30%; (a) stress-strain tensile profile, (b) amplitude sweep.
[0018] Figure 3 illustrates image of core-shell emulsion based free standing films (a) ASR emulsion with pure acrylic acid (cracked film) (b), (c) transparent and (d) flexible film.

DETAILED DESCRIPTIONOF THE INVENTION
[0019] The following is a detailed description of embodiments of the present invention. The embodiments are in such detail as to clearly communicate the invention. However, the amount of detail offered is not intended to limit the anticipated variations of embodiments; on the contrary, the intention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the present invention as defined by the appended claims.
[0020] Each of the appended claims defines a separate invention, which for infringement purposes is recognized as including equivalents to the various elements or limitations specified in the claims. Depending on the context, all references below to the “invention” may in some cases refer to certain specific embodiments only. In other cases, it will be recognized that references to the “invention” will refer to subject matter recited in one or more, but not necessarily all, of the claims.
[0021] Groupings of alternative elements or embodiments of the invention disclosed herein are not to be construed as limitations. Each group member can be referred to and claimed individually or in any combination with other members of the group or other elements found herein. One or more members of a group can be included in, or deleted from, a group for reasons of convenience and/or patentability.
[0022] Unless the context requires otherwise, throughout the specification which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense that is as “including, but not limited to.”
[0023] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.
[0024] As used in the description herein and throughout the claims that follow, the meaning of “a,” “an,” and “the” includes plural reference unless the context clearly dictates otherwise. Also, as used in the description herein, the meaning of “in” includes “in” and “on” unless the context clearly dictates otherwise.
[0025] In some embodiments, the numbers expressing quantities of ingredients, properties such as concentration, and so forth, used to describe and claim certain embodiments of the invention are to be understood as being modified in some instances by the term “about”. Accordingly, in some embodiments, the numerical parameters set forth in the written description are approximations that can vary depending upon the desired properties sought to be obtained by a particular embodiment. In some embodiments, the numerical parameters should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Notwithstanding that the numerical ranges and parameters setting forth the broad scope of some embodiments of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as practicable.
[0026] The recitation of ranges of values herein is merely intended to serve as a shorthand method of referring individually to each separate value falling within the range. Unless otherwise indicated herein, each individual value is incorporated into the specification as if it were individually recited herein.
[0027] Unless otherwise noted, the term “about” refers to ±10% of the non-percentage number that is described, rounded to the nearest whole tenth of an integer. For example, “about 30 minutes” would include 27 minutes to 33 minutes. Unless otherwise noted, the term “about” refers to ±5% of a percentage number. For example, “about 19% by weight” would include 14% to 24% by weight. When the term “about” is discussed in terms of a range, then the term refers to the appropriate amount less than the lower limit and more than the upper limit. For example, from “from about 7.0% to about 19.0% by weight” would include from 2.0% to 24.0% by weight.
[0028] The headings and abstract of the invention provided herein are for convenience only and do not interpret the scope or meaning of the embodiments.
[0029] All methods described herein can be performed in any suitable order unless otherwise indicated herein or otherwise clearly contradicted by context. The use of any and all examples, or exemplary language (e.g. “such as”) provided with respect to certain embodiments herein is intended merely to better illuminate the invention and does not pose a limitation on the scope of the invention otherwise claimed. No language in the specification should be construed as indicating any non-claimed element essential to the practice of the invention.
[0030] Accordingly, an aspect of the present disclosure provides an alkali soluble resin (ASR) comprising: (a) an acrylic acid dimer or 2-Carboxyethyl acrylate as a first co-monomer; and (b) a second co-monomer selected from any or a combination of acrylic acid based monomer, styrene based monomer and maleic anhydride based monomer.
[0031] The acrylic acid dimer/2-Carboxyethyl acrylate is present in the range of about 5% to about 60% by wt. of the total wt. of first co-monomer.
[0032] The first co-monomer is present in the range of about 5% to about 40% by wt. of the total wt. of the alkali soluble resin (ASR). The second co-monomer is present in the range of about 60% to about 95% by wt. of the total wt. of the alkali soluble resin (ASR).
[0033] The acrylic acid based monomer in an amount in the range of about 3% to about 28% by wt. of the total wt. of the second co-monomer. The styrene based monomer in an amount in the range of about 30% to about 60% by wt. of the total wt. of the second co-monomer. The maleic anhydride based monomer in an amount in the range of about 0% to about 10% by wt of the total wt. of the second co-monomer.
[0034] The acrylic acid based monomers is selected from the group consisting of acrylic acid, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, tert-butyl acrylate, iso-butyl acrylate, iso-decyl acrylates other C1 to C12 alkyl acrylates and combinations thereof. The acrylic acid based monomers for the first co-monomer and the second co-monomer are different.
[0035] The styrene based monomer is selected from the group consisting of styrene, a-methyl styrene (isopropenylbenzene), ß-methylstyrene (1-propenylbenzene), 4-methyl styrene (4-vinyl-1-methylbenzene), and 2,3-dimethyl styrene (1-ethenyl-2,3-dimethylbenzene) and combinations thereof.
[0036] The maleic anhydride based monomer is selected from the group consisting of fumaric acids, maleic acid, itaconic acids and combination thereof.
[0037] Another aspect of the present disclosure provides a process for preparation of an Alkali Soluble Resin (ASR) comprising: (a) taking an acrylic acid dimer as a first co-monomer; (b) taking a second co-monomer selected from any or a combination of acrylic acid based monomer, styrene based monomer and maleic anhydride based monomer; and (c) effecting polymerization between said first co-monomer and said second co-monomer in the present of a solvent or without solvent to obtain the Alkali Soluble Resin (ASR).
[0038] In an aspect of the present disclosure provides a process for preparation of an Alkali Soluble Resin (ASR) in which the polymerization is bulk polymerization or solvent polymerization. The solvent used in the step c) of the process for preparation of an Alkali Soluble Resin (ASR) is selected from a group consisting of toluene, xylene and combination thereof.
[0039] The polymerization in step c) is carried out at a temperature in the range of 150-400°C for a period in the range of 20 to 150 minutes.
[0040] In an embodiment, the step effecting bulk polymerization is step c) includes heating said first co-monomer and said second co-monomer in presence of an initiator at a temperature ranging from 200-300 °C for a time period ranging from 30 to 60 minutes.
[0041] In an embodiment, the Alkali Soluble Resin (ASR) is dimer rich acrylic acid-based alkali soluble resin (ASR). Alkali Soluble Resin (ASR) containing acrylate dimer within the polymeric structure thereof. In an embodiment, the Alkali Soluble Resin (ASR) has a number average molecular weight (Mn) ranging from about 6000 to about 20000. In an embodiment, the Alkali Soluble Resin (ASR) has a PDI ranging from about 2 to about 4, preferably, between about 3.2 to about 4.0. In an embodiment, the Alkali Soluble Resin (ASR) has a melting temperature (Tm) ranging from about 40°C to about 55°C, preferably, between about 45°C to about 50°C. In an embodiment, the Alkali Soluble Resin (ASR) has a glass transition temperature (Tg) ranging from about 130°C to about 150°C, preferably, between about 135°C to about 145°C. In an embodiment, the Alkali Soluble Resin (ASR) has an acid content ranging from about 150 to about 300, preferably, between about 225 to about 275.
[0042] In an embodiment, the dimer rich acrylic acid has a dimer (acrylic acid dimer) content ranging from about 5% to about 60% by wt. of the dimer rich acrylic acid. In an embodiment, the dimer rich acrylic acid includes: acrylic acid in an amount ranging from about 40% to about 95% and acrylic acid dimerin an amount ranging from about 5% to about 60% by wt. of the dimer rich acrylic acid.
[0043] Another aspect of the present disclosure provides an emulsion polymers with core-shell structure comprising: 7 to 15 % w/w of an alkali soluble resin (ASR) of the total wt. of the emulsion; 0.5 to 1.5 % w/w of an ammonia solution of the total wt. of the emulsion; 20 to 35 % w/w of a monomer system of the total wt. of the emulsion; 0.2 to 1.2 % w/w of a first initiator of the total wt. of the emulsion; and 0.03 to 0.15 % w/w of a second initiator of the total wt. of the emulsion.
[0044] The monomer system is selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, tert-butyl acrylate, iso-butyl acrylate, iso-decyl acrylates, 2-hydroxy ethyl methacrylate, acrylonitrile, itaconic acid, maleic acid, fumaric acid, styrene, substituted styrene, vinyl acetate and other C1 to C12 alkyl acrylates.
[0045] The first initiator is selected from a group consisting of sodium persulfate (NaPS), potassium persulfate (KPS), Ammonium persulfate (APS), 4,4'-Azobis(4-cyanovaleric acid), hydrogen peroxide, tert-butyl hydrogen peroxide, ascorbic acids, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride and combinations thereof.
[0046] The second initiator is selected from a group consisting of tert-Butyl hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, AIBN, ABCN and combinations thereof.
[0047] In an embodiment of the present disclosure discloses that the emulsion optionally contain 0.1 to 1% of a cross linker. The cross linker is selected from a group consisting of trimethylolpropane triacrylate (TMPTA), poly(ethylene glycol) diacrylate (PEGDA), N,N'-Methylenebisacrylamide (MBA) and combination thereof.
[0048] The emulsion polymer with core-shell structure has a particle size ranging from about 50 nm to about 200 nm. The emulsion polymer with core-shell structure has a viscosity ranging from about 10 cP to about 100 cP. The emulsion polymer with core-shell structure has a pH ranging from about 7.5 to about 8.9. The emulsion polymer with core-shell structure has a solid content ranging from about 30% to about 60% by wt. of the emulsion polymer.
[0049] Another aspect of the present disclosure provides a process for preparation of an emulsion polymers with core-shell structure comprising: (a) preparing a solution of an acrylic acid dimer based Alkali Soluble Resin (ASR); (b) reacting the solution of the acrylic acid dimer based Alkali Soluble Resin (ASR) with a monomer system in presence of a first initiator for a period ranging from 30 minutes to 120 minutes to obtain a polymeric mixture; and (c) effecting post-polymerization of the polymeric mixture in presence of a second initiator to obtain the emulsion polymer with core-shell structure.
[0050] The solution of an acrylic acid dimer based Alkali Soluble Resin (ASR) is prepared by adding 25 to 35 %w/w of Alkali Soluble Resin (ASR) in a solvent. The solvent is water.
[0051] The post-polymerization step (c) is carried out at a temperature in the range of 45 to 65 °C for a period in the range of 1 to 3 hrs.

[0052] In an embodiment, the acrylic acid dimer based Alkali Soluble Resin (ASR) is prepared by effecting polymerization between a first co-monomer being an acrylic acid dimer and a second co-monomer selected from any or a combination of acrylic acid based monomer, styrene based monomer and maleic anhydride based monomer in presence of an initiator. In an embodiment, the step of effecting polymerization comprises effecting bulk polymerization.
[0053] In an embodiment, the Alkali Soluble Resin (ASR) (i.e. the acrylic acid dimer based ASR) has a number average molecular weight (Mn) ranging from about 6000 to about 20000. In an embodiment, the Alkali Soluble Resin (ASR) has a PDI ranging from about 2 to about 4, preferably, between about 3.2 to about 4.0. In an embodiment, the Alkali Soluble Resin (ASR) has a melting temperature (Tm) ranging from about 40°C to about 55°C, preferably, between about 45°C to about 50°C. In an embodiment, the Alkali Soluble Resin (ASR) has a glass transition temperature (Tg) ranging from about 130°C to about 150°C, preferably, between about 135°C to about 145°C. In an embodiment, the Alkali Soluble Resin (ASR) has an acid content ranging from about 150 to about 300, preferably, between about 225 to about 275.
[0054] Still further aspect of the present disclosure provides emulsion polymer with core-shell structure containing acrylic acid dimer based Alkali Soluble Resin (ASR).
[0055] The present disclosure is related to the alkali soluble resins (ASRs), polymers containing core-shell particles and methods of preparation thereof. The present disclosure is, in part, based on the surprising observations by inventors of the present disclosure that utilization of an acrylic acid dimer or 2-Carboxyethyl acrylate as a co-monomer for production of Alkali Soluble Resin (ASR) affords several fold advantages in that – (i) acrylic acid dimer is considered as an impurity in both glacial and ester grade acrylic acid feedstocks, which typically is rejected or is subjected to further treatment to convert the dimer back into the acrylic acid monomer, and accordingly, direct utilization of acrylic acid dimer as one of the co-monomer affords significant economic savings; (ii) the acrylic acid dimer, while participating as a co-monomer in the polymerization process, also controls the molecular weight and molecular weight distribution of ASR (i.e. the copolymers), precluding the need of usage of a chain transfer agent in the polymerization reaction, making the overall process significantly cost effective; and (iii) the ASR prepared using acrylic acid dimer as one of the co-monomers exhibits improved mechanical properties (such as flexibility). Surprisingly, in stark contrast to the conventional ASRs, which are amorphous (glassy) in nature and exhibit only glass transition temperatures (Tg), the ASRs of the present disclosure exhibit low temperature melting peak around 45-50°C apart from high glass transition temperature (Tg) around 140°C, plausibly owing to side chain crystallinity of ASR because of the presence of dimer content therein. Without wishing to be bound by the theory, it is believed that the acrylic acid dimer acts as a chain transfer agent in controlling the molecular weight of the ASR resins.
[0056] In an embodiment, the step of effecting polymerization comprises effecting bulk polymerization between said first co-monomer and said second co-monomer to obtain the Alkali Soluble Resin (ASR). In an embodiment, the step effecting bulk polymerization includes heating said first co-monomer and said second co-monomer in presence of an initiator at a temperature ranging from 150-400 °C for a time period ranging from 20 to 150 minutes. In an embodiment, the step effecting bulk polymerization includes heating said first co-monomer and said second co-monomer in presence of a solvent or without solvent at a temperature ranging from 200-300 °C for a time period ranging from 30 to 60 minutes.
[0057] Another aspect of the present disclosure provides Alkali Soluble Resin (ASR) containing acrylate dimer within the polymeric structure thereof. In an embodiment, the Alkali Soluble Resin (ASR) has a number average molecular weight (Mn) ranging from about 6000 to about 20000. In an embodiment, the Alkali Soluble Resin (ASR) has a PDI ranging from about 2 to about 4, preferably, between about 3.2 to about 4.0. In an embodiment, the Alkali Soluble Resin (ASR) has a melting temperature (Tm) ranging from about 40°C to about 55°C, preferably, between about 45°C to about 50°C. In an embodiment, the Alkali Soluble Resin (ASR) has a glass transition temperature (Tg) ranging from about 130°C to about 150°C, preferably, between about 135°C to about 145°C. In an embodiment, the Alkali Soluble Resin (ASR) has an acid content ranging from about 150 to about 300, preferably, between about 225 to about 275.
[0058] Further aspect of the present disclosure relates to a process for preparation of emulsion polymer with core-shell structure, said process including the steps of: (a) preparing a solution of an acrylic acid dimer based Alkali Soluble Resin (ASR); (b) reacting the solution of anacrylic acid dimer based Alkali Soluble Resin (ASR) with a monomer system in presence of a first initiator for a period ranging from 30 minutes to 120 minutes to obtain a polymeric mixture; and (c) effecting post-polymerization of the polymeric mixture in presence of a second initiator to obtain the emulsion polymer with core-shell structure. In an embodiment, the emulsion polymer with core-shell structure has a particle size ranging from about 50 nm to about 200 nm. In an embodiment, the emulsion polymer with core-shell structure has a particle size ranging from about 50 nm to about 200 nm. In an embodiment, the emulsion polymer with core-shell structure has a viscosity ranging from about 10 cP to about 100 cP. In an embodiment, the emulsion polymer with core-shell structure has a pH ranging from about 7.5 to about 8.9. In an embodiment, the emulsion polymer with core-shell structure has a solid content ranging from about 30% to about 60% by wt. of the emulsion polymer. In an embodiment, the Alkali Soluble Resin (ASR) (i.e. the acrylic acid dimer based ASR) has a number averaged molecular weight (Mn) ranging from about 6000 to about 20000. In an embodiment, the Alkali Soluble Resin (ASR) has a PDI ranging from about 2 to about 4, preferably, between about 3.2 to about 4.0. In an embodiment, the Alkali Soluble Resin (ASR) has a melting temperature (Tm) ranging from about 40°C to about 55°C, preferably, between about 45°C to about 50°C. In an embodiment, the Alkali Soluble Resin (ASR) has a glass transition temperature (Tg) ranging from about 130°C to about 150°C, preferably, between about 135°C to about 145°C. In an embodiment, the Alkali Soluble Resin (ASR) has an acid content ranging from about 150 to about 300, preferably, between about 225 to about 275.

EXAMPLES
[0059] The disclosure will now be illustrated with working examples, which is intended to illustrate the working of disclosure and not intended to take restrictively to imply any limitations on the scope of the present disclosure. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood to one of ordinary skill in the art to which this disclosure belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice of the disclosed methods and compositions, the exemplary methods, devices and materials are described herein. It is to be understood that this disclosure is not limited to particular methods, and experimental conditions described, as such methods and conditions may vary.
Materials
[0060] All the glassware was oven-dried prior to use and all synthesis was conducted in an inert atmosphere unless otherwise specified. Aqueous solutions were prepared with deionized water (Millipore). All Polymers were vacuum dried at 40°C and 10-3 mbar for 24 h before performing each test. The ASR reactions were carried out in high temperature high pressure parr 4848 (Model Parr 4533) instrument having temperature range 450 °C with maximum pressure 50 bar (750 psi).
[0061] Acrylic acid, (BPCL, 99%); Styrene, (CDH, 98%); alpha-Methyl styrene (Sigma Aldrich, 99%); Methyl methacrylate (Fujifilm Wako, 95%); Butyl acrylate (Fujifilm Wako, 98%); Maleic anhydride (Across organic, 99%); Trimethylolpropane ethoxylate triacrylate (TMPTA, Mn=692) (Fujifilm Wako, 98%); Sodium persulphate, (CDH, 95%); Ammonia solution (Fujifilm Wako, 28%); tert-Butyl hydrogen peroxide (Matrix Material Science, 96%); 4-Methoxy phenol (Sigma Aldrich, 98%); 4-Methoxy phenol (CDH, 98%).
Synthesis of acrylic acid dimerbased alkali soluble resins (ASRs)
[0062] General Methodology: Alkali soluble resins (ASRs) were prepared by using high temperature high pressure Parr 4848 (Model Parr 4533) instrument having temperature range 450°C with maximum pressure 50 bar (750 psi). The reactor was charged with requisite amounts of acrylic acid dimer (as one of the co-monomer) and one or more other co-monomers. The reaction was in bulk polymerization. ASR with solution polymerization was also performed for comparative studies. The reactor was set with 260°C for 45 min. The maximum pressure observed was 290 psi during the course of reactions.
[0063] ASR-1 (Comparative Example): The ASR-1 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene and 50 gm of glacial acrylic acid. The reaction was performed by bulk polymerization at 260°C for 45 min following the general methodology provided above.
[0064] ASR-2. The ASR-2 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene and 50 gm of acrylic acid dimer (10% dimer content in acrylic acid). The reaction was performed by bulk polymerization at 260°C for 45 min following the general methodology provided above.
[0065] ASR-3. The ASR-3 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene and 50 gm of acrylic acid dimer (10% dimer content in acrylic acid). The reaction was performed using solution polymerization using xylene as solvent at 260°C for 45 min.
[0066] ASR-4. The ASR-4 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene and 50 gm of acrylic acid dimer (20% dimer content in acrylic acid). The reaction was performed bulk polymerization at 260°C for 45 min following the general methodology provided above.
[0067] ASR-5. The ASR-5 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene and 50 gm of acrylic acid dimer (32% dimer content in acrylic acid). The reaction was performed bulk polymerization at 260°C for 45 min following the general methodology provided above.
[0068] ASR-6. The ASR-6 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene and 50 gm of ester grade of acrylic acid. The reaction was performed bulk polymerization at 260 °C for 45 min following the general methodology provided above.

[0069] ASR-7. The ASR-7 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene 45 gm of dimer rich acrylic acid (32% dimer content in acrylic acid) and 5mL of maleic anhydride. The reaction was performed bulk polymerization at 260 °C for 45 min following the general methodology provided above.
[0070] ASR-8. The ASR-8 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene 45 gm of dimer rich acrylic acid (32% dimer content in acrylic acid), 0.900 g of maleic anhydride, 0.900 g of hydroquinone, 0.230 g of 4-Methoxy phenol and 0.165 g PTZ. The reaction was performed by bulk polymerization at 260 °C for 45 min following the general methodology provided above.
[0071] ASR-9. The ASR-9 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene and 50 gm of glacial acrylic acid. The reaction was performed by bulk polymerization at 260°C for 90 min following the general methodology provided above.
[0072] ASR-10. The ASR-10 was synthesised using 50 gm of styrene, 50 gm of alpha-methyl styrene and 50 gm of dimer rich acrylic acid (32% dimer content in acrylic acid). The reaction was performed by bulk polymerization at 260°C for 90 min following the general methodology provided above.
[0073] Table 1 below provides details pertaining to synthesized ASRs
Table 1: Details pertaining to synthesized ASRs
Parameter ASR-1 ASR-2 ASR-3 ASR-4 ASR-5 ASR-6
Acrylic acid dimer content Glacial Acrylic acid (AA) AA Dimer content 10% AA Dimer content 10% AA Dimer Content 20% AA Dimer Content 32% Ester Grade AA
Other monomers Sty (33.3%)
AMS (33.3%)
AA(33.3%) Sty (33.3%)
AMS (33.3%)
AA(33.3%) Sty (33.3%)
AMS (33.3%)
AA(33.3%) Sty (33.3%)
AMS (33.3%)
AA(33.3%) Sty (33.3%)
AMS (33.3%)
AA(33.3%) Sty (33.3%)
AMS (33.3%)
AA(33.3%)
Synthesis method Bulk Bulk Solution Solution Bulk Bulk
Reaction Time (Min) 45 45 45 45 45 45
NON-VOC 98% 98% 98% 98% 98% 98%
Yield (%) >95 >95 >95 >95 >95 >95
(Mn)
PDI 18,400
2.51 8800
2.06 6900
1.95 6300
1.94 8900
2.16 8900
2.05
Tm (oC) Not observed 45-48 45-48 45-48 45-48 45-48
Tg (oC) 115 140 140 140 140 140
Acid content 250 241 235 236 266 223

Parameter ASR-7 ASR-8 ARS-9 ASR-10
Acrylic acid dimer content AA dimer 32%
AA dimer content 32% Glacial Acrylic acid (AA) AA Dimer content 32%
Other monomers Sty (33.3%)
AMS (33.3%)
AA(23.3%)
MA(10%) Sty (33.3%)
AMS (33.3%) AA(30.17%)
MA(1.80%) MEHQ(0.46%), PTZ(0.33%) Sty (33.3%)
AMS (33.3%
AA(33.3%) Sty (33.3%)
AMS (33.3%)
AA(33.3%)
Synthesis method Bulk Bulk Bulk Bulk
Reaction Time(Min) 45 45 90 90
NON-VOC 98% 98% 98% 98%
Yield (%) >95 >95 >95 >95
(Mn)
PDI 17,700
2.35 10,600
1.65 18,700
2.28 16,000
2.04
Tm (oC) 45-48 45-48 Not observed 45-48
Tg(oC) 140 140 115-120 140
Acid content 192 184 244 237
Note: The dimer content is w.r.t. acrylic acid; and the composition of the feed has styrene/alpha-methyl styrene/ acrylic acid = 0.33/0.33/0.33 wt% ratio. Xylene was used as solvent in solution polymerization.
Synthesis of emulsion polymer with core-shell structure using Dimer rich alkali soluble resins (ASRs)
[0074] General Methodology: In 1-liter 3-neck flask equipped with mechanical stirrer, condenser, thermometer and oil bath, 28.6 g of respective ASR was vigorously stirred in water (115 mL) with temperature of about 85°C under nitrogen atmosphere. Afterwards, 7.86 g of ammonia solution was added drop wise and stirred till complete dissolution of ASR to prepare a solution of acrylic acid dimer based ASR. A shot of initiator sodium persulfate (NaPS) was added at 80°C. After 5 min, a monomer system containing MMA, BA, TMPTA and NaPS solutions were added separately, simultaneously, continuously over a period of 2 hours. After completion of the reaction, the reaction mixture was held for 2 hours. Further, post-polymerization of the reaction mixture was done at 55°C to minimize the residual monomers. The obtained emulsion was filtered using nylon cloth to obtain core-shell emulsion particles.
[0075] E-1. The composition for preparation of E-1 was 28.60 g of ASR-1, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide.
[0076] E-2. The composition for preparation of E-2 was 28.60 g of ASR-1, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. E-2 could be realized with high solid content. Further, post-polymerization was done with tert-Butyl hydrogen peroxide.
[0077] E-3. The composition for preparation of E-3 was 28.60 g of ASR-1, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of PEGDA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide.

[0078] E-4. The composition for preparation of E-4 was 28.60 g of ASR-2, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide.
[0079] E-5. The composition for preparation of E-5 was 28.60 g of ASR-4, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide.
[0080] E-6. The composition for preparation of E-6 was 28.60 g of ASR-4, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide. E-6 could be realized with high solid content.
[0081] E-7. The composition for preparation of E-7 was 28.60 g of ASR-5, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide.
[0082] E-8. The composition for preparation of E-8 was 28.60 g of ASR-5, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide. E-8 could be realized with high solid content.

[0083] E-9. The composition for preparation of E-9 was 28.60 g of ASR-7, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide.
[0084] E-10. The composition for preparation of E-10 was 28.60 g of ASR-8, neutralized with 7.86 g of ammonia solution; and the monomer system was 33.33 g of butyl acrylate (BA), 33.33 g of methyl methacrylate (MMA) and 0.33 g of TMPTA using initiator sodium persulfate (NaPS) with reaction temperature of about 80°C. Further, post-polymerization was done with tert-Butyl hydrogen peroxide.
Characterization methods
[0085] NMR spectra were recorded using a Bruker 600 spectrometer at ambient probe temperatures and referenced as follows: 1H: residual internal CHCl3 7.26 ppm; DMSO-d6 2.50 ppm; FT-IR spectra were recorded as neat with ATR on BRUKER TENSOR-27, with Zink Selenide window spectrometer in the range of 600-4000 cm-1 (Spectral Resolution = 4 cm-1; 100 scans). The pH of the ASR emulsion was measured using potentiometric auto titrator system Metrohm AG.
Solid Content and Gravimetric Conversion
[0086] The emulsion polymer was dried to a constant mass at temperature 130°C (according to, ISO 1625) and the solids content is then expressed as the percentage ratio of the dry matter to the total mass of the sample.
Theoretical solid content % = total introduced solid × 100 / total weight
Actual solid content % = weight of the sample after drying × 100 / weight of the sample before drying
Gravimetric Conversion = actual solid content % / theoretical solid content
Coagulum Content
[0087] The filterable solids were dried. The coagulum content was then calculated according to

Coagulation% = Mf/ (solid%× Ms + Mf)
Where, Mf and Ms are the weights of dried filterable solids and filtered latex, respectively.
Stability of the ASR Emulsion (emulsion polymer with core-shell structure)
[0088] The ASR emulsion was stored at room temperature as well as 60 °C and 0 °C for six months, or added to a CaCl2 solution or diluted with distilled water, and then observed whether there was a phenomenon of stratification, precipitation, flocculation, and so on, to evaluate its storage stability, chemical stability, and dilution stability, respectively.
Preparation of Films
[0089] The ASR emulsion was poured onto aluminium petri-dish and dried for 24 h at room temperature, then further dried at 60°C for 24 h to obtain the film.
Size exclusion chromatography (SEC)
[0090] Gel permeation chromatography (GPC) measurement was performed at ambient temperature on Malvern Viscotek TDA GPC Technologies (model 1260 GPC/ SEC MDS) and T4000, Org GPC/SEC Col (Part no. CLM3004) columns were used. Tetrahydrofuran (THF) was used as an eluent with a flow rate of 1 mL/min. The system was calibrated using linear poly(styrene) of narrow polydispersity index as an internal standard. The typical sample concentration and injection volumes were 1.0 mg mL-1 and 100 µL, respectively. The results were processed using the corresponding Malvern software referring RI signal.
Thermal Analysis
[0091] The thermal decomposition study was recorded in nitrogen atmosphere by thermo gravimetric analysis (TGA) technique on a “TGA/DSC 1” instrument with SDTA sensor from Perkin Elmer 8000. The temperature, weight and tau lag were calibrated using the Aluminium/Zinc standard sample. High purity nitrogen (99.999%) was passed at a flow rate of 20 mL/min throughout the experiments to avoid contamination from the external atmosphere. The experiments were performed using alumina pan as sample holder and as the reference by using 5-10 mg samples. Thermal stability was investigated by heating from 25 °C to 600 °C at a heating rate of 5 °C/min. Each sample was tested for at least three times and the error limit is <2%. The measurement of phase-transition temperature was recorded by differential scanning calorimeter (DSC) using a DSC1/700W with instrument Perkin Elmer 8000 with Intercooler attachments. The temperature, heat changes and tau lag were calibrated using the pure Indium/Zinc standard sample (In/Zn 156.6/419.5 °C). The DSC was also calibrated with deionized water for low temperature measurements. Standard aluminium pan with a pin was used as reference. The DSC measurements were performed successively through a heat-cool-heat-cool-heat (6 steps) program to ensure the phase transitions, as follows: step 1: heating from -50 °C to 180 °C at 5 °C/min and holding for 2 min; step 2: cooling from 180 °C to -50 °C at a rate of 40 °C min-1 and holding for 2 min; and this repeated for consecutive five cycles.
DLS analysis
[0092] DLS measurements were carried out on a Malvern Mastersizer Nano system equipped with a 633 nm He-Ne laser. 3 mL of the sample was used in a cuvette (PLASTIBRAND disposable cuvettes) and measured for 10 runs with a 10 s time interval. The average of at least five measurements was reported in the data.
Rheology studies
[0093] The ASR emulsion polymer was studied forrheological properties. The rheological test measurements were carried out under atmospheric conditions using Anton Parr Rheometer (MCR302) with SN81948116-81948215; FW4.42; slot (8,-1); adj (9,0)d, measuring system: CP25-1-SN5270;[d= 0.05 mm], Peltier temperature control. The viscosity was performed using cylindrical cone SN81936601; FW4.42; slot (7,-1); adj (9,0)d, measuring system: CC27-SN20708; [d = 0.05 mm], Peltier temperature control.
[0094] In Figure 1, Higher the solid content higher is the viscosity for the dimer free (glacial) acrylic acid ASR based emulsion. Viscosities were well controlled in case of dimer rich ASR based emulsions. In case of 10% dimer rich ASR emulsion, the viscosity was in the range of 15 cP and the viscosity was not affected much even after increasing the solid content from 40% to 50%. It could be due to chain transfer effect of ASR at higher dimer contents.
[0095] The rheological nature of the dimer rich and dimer free acrylic acid-based ASR emulsion was studied using an oscillatory rheometer. The stress-strain profile depicts the tensile nature of the gel, as shown in Figure 2a, which illustrates the shear thinning behaviour. Particularly, ASR emulsion prepared from D0= glacial acrylic acid shows sudden drop at yield point under strain. Whereas dimer rich ASR emulsion sustain the stretching and lower the strain. It could be due to presence of side chain effect of dimerized acrylic acid makes more flexible. The linear viscoelastic behaviour was assessed by using an amplitude sweep test at 25 °C. In case of D0, below 15% strain, the G?(?) (loss modulus) is independent of the applied strain, indicating that the gel has a linear viscoelastic range below 15% as depicted in Fig. 2b. The storage modulus G' is greater than G?. The cross over point was observed at around 15% deformation of strain for ASR emulsion prepared from D0= glacial acrylic acid. Whereas dimer rich ASR emulsion (30% dimer rich ASR emulsion) the cross over point was observed at around 100%. After the critical-strain region, the loss modulus G? decreases drastically, indicating the collapse of the viscoelastic structure and changes to a quasi-liquid state.
[0096] Table 2 below provides details of the synthesized emulsion polymer with core-shell structure (i.e. ASR emulsion polymer)
Table 2: Details pertaining to the synthesized emulsion polymer with core-shellstructure
Parameter E-1 E-2 E-3 E-4 E-5 E-6 E-7 E-8 E-9 E-10
General Forml. MMA-BA MMA-BA (1%) PEGDA Dimer (10%) Dimer (20%) Dimer (20%) Dimer (32%) Dimer (32%) MA(5%) MA, PTZ, MEHQ
Solid content (%) 37.0 49.1 38.2 37.2 39.2 49.2 38.3 49.6 38.3 37.6
Particle size (nm) 73 78 84 63 68 63 69 64 78 110
Viscosity (cP) 62 497 65 18 15 58 15 23 99 37
pH 8.3 8.1 8.0 8.4 8.1 8.3 7.8 8.1 7.6 8.0
Rheology behaviour Thixotropic Thixotropic Thixotropic Thixotropic Thixotropic Thixotropic Thixotropic Thixotropic Thixotropic Thixotropic
Film properties Crack Transparent Crack Transparent Crack Transparent Flexible Transparent Flexible Transparent Flexible Transparent Flexible Transparent Flexible Transparent Flexible Transparent Flexible Transparent
Emulsion stability Stable stable Stable quite stable quite stable quite stable quite stable quite stable quite stable quite stable
slight colored
Note:The reaction was performed with ASR =30 wt%, MMA/BA (1/1 wt%, 1% TMPTA/PEGDA wrt MMA/BA. In all cases Yield was =95%. VOC was 1.5 - 2.0 % and formation of coagulation was =0.5%.
[0097] Fig. 3 illustrates exemplary images of thin films after drying (a) ASR emulsion with pure acrylic acid (b), (c) transparent and (d) flexible thin film of 1 mm thickness prepared using acrylic aciddimer.
[0098] The advantageous ASRs realized in accordance with embodiments of the present disclosure can find utility in wide verities of applications such as in coating and ink industry as polymeric surfactant, as sizing agent in paper industry, as pigment dispersant and as gloss improver. The emulsion polymers, realized in accordance with embodiments of the present disclosure using dimer rich ASR, has better film forming properties, small particle size, high stability, low VOC content, and superior visco-elastic properties.
,CLAIMS:1. An alkali soluble resin (ASR) comprising:
(a) an acrylic acid dimer as a first co-monomer; and
(b) a second co-monomer selected from any or a combination of acrylic acid based monomer, styrene based monomer and maleic anhydride based monomer.
2. The resin as claimed in claim 1, wherein the acrylic acid dimer is present in the range of about 5% to about 60% by wt. of the total wt. of first co-monomer.
3. The resin as claimed in claim 1, wherein the first co-monomer is present in the range of about 5% to about 40% by wt. of the total wt. of the alkali soluble resin (ASR).
4. The resin as claimed in claim 1, wherein the second co-monomer is present in the range of about 60% to about 95% by wt. of the total wt. of the alkali soluble resin (ASR).
5. The resin as claimed in claim 1, wherein the acrylic acid based monomer in an amount in the range of about 3% to about 28% by wt. of the total wt. of the second co-monomer.
6. The resin as claimed in claim 1, wherein the styrene based monomer in an amount in the range of about 30% to about 60% by wt. of the total wt. of the second co-monomer.
7. The resin as claimed in claim 1, wherein the maleic anhydride based monomer in an amount in the range of about 0% to about 10% by wt of the total wt of the second co-monomer.
8. The resin as claimed in claim 1, wherein the acrylic acid based monomers is selected from the group consisting of acrylic acid, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methyl methacrylate, ethyl methacrylate, butyl methacrylate, tert-butyl acrylate, iso-butyl acrylate, iso-decyl acrylates other C1 to C12 alkyl acrylates and combinations thereof.
9. The resin as claimed in claim 8, wherein theacrylic acid based monomers for the first co-monomer and the second co-monomer are different.
10. The resin as claimed in claim 1, wherein the styrene based monomer is selected from the group consisting of styrene, a-methylstyrene (iso-propenylbenzene), ß-methylstyrene (1-propenylbenzene), 4-methyl styrene (4-vinyl-1-methylbenzene), and 2,3-dimethyl styrene (1-ethenyl-2,3-dimethylbenzene) and combinations thereof.
11. The resin as claimed in claim 1, wherein the maleic anhydride based monomer is selected from the group consisting of fumaric acids, maleic acid, itaconic acids and combination thereof.
12. A process for preparation of an Alkali Soluble Resin (ASR) comprising:
(a) taking an acrylic aciddimer as a first co-monomer;
(b) taking a second co-monomer selected from any or a combination of acrylic acid based monomer, styrene based monomer and maleic anhydride based monomer; and
(c) effecting polymerization between said first co-monomer and said second co-monomer in the present of a solvent or without solvent to obtain the Alkali Soluble Resin (ASR).
13. The process as claimed in claim 12, wherein the polymerization is bulk polymerization or solvent polymerization.
14. The process as claimed in claim 12, wherein the solvent is selected from a group consisting of toluene, xylene and combination thereof.
15. The process as claimed in claim 12, wherein the polymerization in step c) is carried out at a temperature in the range of 150-400°C for a period in the range of 20 to 150 minutes.
16. An emulsion polymers with core-shell structure comprising:
7 to15% w/w of an alkali soluble resin (ASR) of the total wt. of the emulsion;
0.5 to 1.5% w/w of an ammonia solution of the total wt. of the emulsion;
20 to 35% w/w of a monomer system of the total wt. of the emulsion;
0.2 to 1.2% w/w of a first initiator of the total wt. of the emulsion; and
0.03 to 0.15% w/w of a second initiator of the total wt. of the emulsion.
17. The emulsion as claimed in claim 16, wherein the alkali soluble resin (ASR) is defined in claim 1.
18. The emulsion as claimed in claim 16, wherein the monomer system is selected from the group consisting of acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, decyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, tert-butyl acrylate, iso-butyl acrylate, iso-decyl acrylates, 2-hydroxy ethyl methacrylate, acrylonitrile, itaconic acid, maleic acid, fumaric acid, styrene, substituted styrene, vinyl acetate and other C1 to C12 alkyl acrylates.
19. The emulsion as claimed in claim 16, wherein the first initiator is selected from a group consisting of sodium persulfate (NaPS), potassium persulfate (KPS), Ammonium persulfate (APS), 4,4'-Azobis(4-cyanovaleric acid), hydrogen peroxide, tert-butyl hydrogen peroxide, ascorbic acids, 2,2'-azobis[2-(2-imidazolin-2-yl)propane] dihydrochloride and combinations thereof.
20. The emulsion as claimed in claim 16, wherein the second initiator is selected from a group consisting of tert-Butyl hydrogen peroxide, benzoyl peroxide, lauroyl peroxide, AIBN, ABCN and combinations thereof.
21. The emulsion as claimed in claim 16, wherein the emulsion optionally contain 0.1 to 1% of a cross linker.
22. The emulsion as claimed in claim 21, wherein the cross linker is selected from a group consisting of TMPTA, PEGDA, MBA and combination thereof.
23. The emulsion as claimed in claim 18, wherein the emulsion polymer with core-shell structure has a particle size ranging from about 50 nm to about 200 nm.
24. The emulsion as claimed in claim 18, wherein the emulsion polymer with core-shell structure has a viscosity ranging from about 10 cP to about 100 cP.
25. The emulsion as claimed in claim 18, wherein the emulsion polymer with core-shell structure has a pH ranging from about 7.5 to about 8.9.
26. The emulsion as claimed in claim 18, wherein the emulsion polymer with core-shell structure has a solid content ranging from about 30% to about 60% by wt. of the emulsion polymer.
27. A process for preparation of an emulsion polymers with core-shell structure comprising:
(a) preparing a solution of an acrylic acid dimer based Alkali Soluble Resin (ASR);
(b) reacting the solution of the acrylic acid dimer based Alkali Soluble Resin (ASR) with a monomer system in presence of a first initiator for a period ranging from 30 minutes to 120 minutes to obtain a polymeric mixture; and
(c) effecting post-polymerization of the polymeric mixture in presence of a second initiator to obtain the emulsion polymer with core-shell structure.
28. The process as claimed in claim 27, wherein the solution of an acrylic acid dimer based Alkali Soluble Resin (ASR) is prepared by adding 25 to 35% w/w of Alkali Soluble Resin (ASR) in a solvent.
29. The process as claimed in claim 27, wherein the solvent is water.
30. The process as claimed in claim 27, wherein the post-polymerization step (c) is carried out at a temperature in the range of 45 to 65 °C for a period in the range of 1 to 3 hrs.