[1] The present invention relates to co-polyester polymer. Particularly, the present invention relates to water-soluble co-polyester polymer. Specifically, the present invention relates to water-soluble co-polyester polymer used for substrate coating. The process of synthesis and applications are also disclosed.

BACKGROUND OF THE INVENTION

[2] Biaxially oriented polyester film made from stretched polyethylene terephthalate (PET) and is used for its high tensile strength, chemical and dimensional stability, transparency, reflectivity, gas barrier properties, and electrical insulation. The manufacturing process begins with a resin of molten polyethylene terephthalate (PET) being extruded onto a chill roll, which quenches it into the amorphous state. It is then biaxially oriented by drawing under special thermal condition, which causes molecular relaxation. The most common way of doing this is the sequential process, in which the film is first drawn in the machine direction using heated rollers and subsequently drawn in the transverse direction, i.e. orthogonally to the direction of travel, in a heated oven. It is also possible to draw the film in both directions simultaneously, although the equipment required for this is somewhat more elaborate. The temperature, orientation, and crystallinity percentage governs the final properties of the BOPET films.

[3] This biaxially oriented film design is largely employed to the packaging material for developing packaging products. The surface energy of the biaxially oriented polyethylene terephthalate (BOPET) films is very less 44-46 Dyne/cm and it’s adhesion to ink (printing) or metallized Aluminum is very less, which makes it less suitable for printing or Aluminum metallization. Generally, the BOPET films are either corona treated or coated with other co polyester polymers to increase their surface energy. The corona treated surface of the BOPET base film degrades during placement or use. If the temperature and humidity percentage are high, the degradation will be faster. Further, the coating polymers are mostly solvent-based and thus, the evaporation of these solvents may harm to the environment. Many efforts have been done so far to obtain a water-based co-polyester polymer, which can obviate the drawbacks of prior-art and will provide an environmental friendly solution to the problem. Similarly, there is no polymer is disclosed which can provide wide range of printability performance when coated over BOPET or Aluminum sheets.

[4] Further, the biaxially oriented films are used in peelable sealable packaging whereas the biaxially oriented copolyester films are coated with a polymer on one side. Such coating polymer is expected to impart peelable sealable properties to the bioaxially oriented copolyester film. The peelable sealable films are generally used to pack frozen foods and ready to eat meals preferably in A-PET, C-PET, G-PET and PVDC trays. Therefore, the coating polymer is also expected to impart anti-fog properties. Additionally, the coating polymer is also expected to affect the clarity of the biaxially oriented copolyester polymer at minimum to provide a clear and transparent packaging solution. Conventionally used polymers for the coating of biaxially oriented films to prepare peelable sealable films are either organic solvent- based or extrusion based. These polymers are coated to the biaxially oriented film in a coating thickness of about 2 to 3 GSM. Such coating increase the hazing of the film by 8 to 12 %. Further, these films are required to be stored in refrigerator while in transport to avoid blocking. The peelable sealable films prepared by such conventional polymers are also not efficient to provide expected anti-fog properties.

[5] Therefore, there is an urgent need for inventing and developing a water soluble polymer which when coated to BOPET film provide increase in surface energy along with wide range of printability performances and high metal to film bond strength with minimum gain in weight. Further, there is an unmet need to invent and develop a water-soluble polymer, which can be used to coat Aluminum sheets to impart wide range of printability performance to it with minimum gain in weight. There is also an unmet need for a polymer which can provide an efficient peelable sealable biaxially oriented film with minimum haze % and anti-fog properties.

SUMMARY OF THE INVENTION

[6] A water-soluble co-polyester polymer used for substrate coating is provided.

[7] In one aspect, the present invention provides a water-soluble co-polyester polymer, which can be used for inline or offline coating of substrate to increase their surface energy and surface adhesion. [8] In one another aspect, the present invention provides a water-soluble co-polyester polymer, which can be used for inline coating or offline coating of substrate provide wide range of printability performance.

[9] In one another aspect, the present invention provides a water-soluble co-polyester polymer which when inline coated on BOPET films enhance their surface properties, provides wide range of printability performance and metal to film bond strength.

[10] In one another aspect, the present invention provides a water-soluble co-polyester polymer which when coated on metal sheets or foil (e.g. Aluminum) enhance the compatibility and hence adhesion of ink, provide wide range of printability performance.

[11] In one another aspect, the present invention provides a water-soluble co-polyester polymer, which imparts excellent adhesion, and printability properties to the substrate when coated with the water-soluble co-polyester polymer.

[12] In one another aspect, the present invention provides a water-soluble co-polyester polymer, which provides excellent adhesion to ink and Aluminum (metallization) when the BOPET is coated with the water-soluble co-polyester polymer. Thus, it provides wide range of printability performance over the BOPET inline coated with the co-polyester polymer of the present invention. Similarly, the inline coating of BOPET with the co-polyester polymer of the present invention also increases adhesion to Aluminum metal in the process of metallization and thus provide excellent metal to film bond strength.

[13] In one another aspect, the present invention provides a water-soluble co-polyester polymer, which can be coated in very thin layer thickness and at very less weight gain.

[14] In one another aspect, the present invention provides a water-soluble co-polyester polymer for substrate coating, which provides a wide range of printability performance with water-based ink systems, thus avoiding solvent-based ink systems.

[15] In one another aspect, the present invention provides an environment friendly solution to the packaging industry.

[16] In yet another aspect, the present method provides a process of synthesis of the water- soluble co-polyester polymer. [17] In yet another aspect, the present invention provides a coating composition comprising the polymer of the present invention which when coated on a biaxially oriented film the will provide excellent peelable sealable film properties including desired peal strength, minimum or negligible hazing and anti-fog properties.

[18] Various aspects of the invention will now be described herein in detail. Still other aspects, features, and advantages of the present invention are readily apparent from the entire description thereof, including the embodiments, examples and implementations. Any subject matter described in the specification can be combined with any other subject matter in the specification to form a novel combination. The invention is also capable of other and different examples and aspects, and its several details can be modified in various respects, all without departing from the spirit and scope of the present invention. Accordingly, the descriptions are to be regarded as illustrative in nature, and not as restrictive. Furthermore, the terminology and phraseology used herein is solely used for descriptive purposes and should not be construed as limiting in scope.

DETAILED DESCRIPTION OF THE INVENTION Abbreviations

[19] BOPET: Biaxially oriented polyethylene terephthalate,

[20] IPA: Isophthalic acid

[21] SAMSDE: 5-sulphoisophtalic acid, monosodium salt, dimethyl ester

[22] EG: Ethylene glycol

[23] DEG: Diethylene glycol

[24] PDO: 1,3-propane diol

[25] CHDM: Cyclohexane di-methanol

[26] UOM: Unit of measurement

[27] GSM: Gram per square meter [28] Min: Minute(s)

[29] Hr/hr: Hour(s)

[30] °C: Degree Centigrade Definitions

[31] It is to be understood that the terminology used herein is for the purpose of describing particular embodiments only, and is not intended to be limiting. As used in this specification and the appended claims, the singular forms "a," "an" and "the" include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to "monomer" includes one or more such monomers and the like.

[32] Unless defined otherwise, all technical, scientific or other terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention pertains. Although other methods and materials similar, or equivalent, to those described herein can be used in the practice of the present invention, the preferred materials and methods are described herein.

[33] In describing and claiming the present invention, the following terminology will be used in accordance with the definitions set out below.

[34] As used herein, "about" will be understood by persons of ordinary skill in the art and will vary to some extent depending upon the context in which it is used. If there are uses of the term which are not clear to persons of ordinary skill in the art, given the context in which it is used, "about" will mean up to plus or minus 10% of the particular term.

[35] The terms “water-soluble co-polyester polymer”, "polymer", “co-polyester polymer” or “the polymer of the present invention” are used interchangeably and refer to the water soluble co-polyester polymer discloses in the present invention.

[36] The term "monomer" refers to a single molecule or unit, which when go with similar monomer or different monomer for polymerization reaction, synthesizes a polymer.

[37] The term "pre-polymer" refers to a monomer or system of monomers that have been reacted to an intermediate molecular mass state. This material is capable of further polymerization by reactive groups to a fully cured high molecular weight state. As such, mixtures of reactive polymers with un-reacted monomers may also be referred to as pre polymers.

[38] The term "reaction product" refers to an intended and/or probable resulting product of a chemical reaction under given reaction conditions/parameters e.g. time, temperature and other conditions/parameters.

[39] The term "dicarboxylic acid" refers to an organic compound containing two carboxyl functional groups ( CO(>H). The term includes the esters /carboxylates of dicarboxylic acids. The dicarboxylic acid used in the present invention can be an aliphatic dicarboxylic acid, an aliphatic dicarboxylate, a cycloaliphatic dicarboxylic acid, a cycloaliphatic dicarboxylate, an aromatic dicarboxylic acid and an aromatic dicarboxylate. The non-exhaustive list of such dicarboxylic acids comprises isophthalic acid, dimethyl isophthalate, terephthalic acid, dimethyl terephthalate, sebacic acid, dimethyl 2,6-naphthalate, naphthalene dicarboxylic acid, dimethyl 1,4-naphthalate, succinic acid, adipic acid, azelaic acid, 2,6-naphthalene dicarboxylic acid, glutaric acid, maleic acid, fumaric acid, oxalic acid, malonic acid, pimelic acid and suberic acid.

[40] The term “diol”, "first diol" or “second diol” refers to a chemical compound containing two hydroxy] group.

[41] The term "aromatic sulfonate" refers to metal salts of aromatic sulfonates. The non- exhaustive list of such aromatic sulfonates comprises sulfonate salts of highly reactive or transition metal e.g. Na, K, Mg, Ca, Ni, or Fe. The non-limiting examples of aromatic sulfonate includes metal salt of sodium 5-sulfophthalic acid, sulfonate isophthalic acid, sulfonate 2,6 naphthalene dicarboxylate or as disclosed in various patent and non-patent documents. Preferably, the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester.

[42] The term “biaxially oriented film”, "BOPET" or “PET” are used interchangeably and refers to polyethylene terephthalate. Preferably, the term refers to biaxially oriented polyethylene terephthalate film.

[43] The term "intrinsic viscosity" (I.V.) refers to a measure of a solute's contribution to the viscosity of a solution. I.V. as used herein is measured by dilute solution using an Ubbelohde capillary viscometer. [44] The term "carboxylic end group content" refers to -COOH end group present at the end of polymer chains and is determined by the method described in the example section of the present disclosure.

[45] The terms "glass transition temperature" and “T _g ” can be used interchangeably and refer to the temperature at which a chemical compound specifically polymers turn from a ductile and soft materia] to a hard, brittle or glass like material.

[46] Ratios, concentrations, amounts, and other numerical data may be presented herein in a range format. It is to be understood that such range format is used merely for convenience and brevity and should be interpreted flexibly to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, 5 to 40 mole% should be interpreted to include not only the explicitly recited limits of 5 to 40 mole %, but also to include sub-ranges, such as 10 mole % to 30 mole %, 7 mole % to 25 mole %, and so forth, as well as individual amounts, including fractional amounts, within the specified ranges, such as 15.5 mole%, 29.1 mole%, and 12.9 mole%.

[47] The present invention discloses a co-polyester polymer. Particularly, a water-soluble co-polyester polymer is disclosed. Specifically, a water-soluble co-polyester polymer used for substrate coating is disclosed. The process of synthesis of the said polymer is also disclosed.

[48] In one embodiment, the present invention discloses a water-soluble co-polyester polymer used for substrate coating is provided.

[49] In one another embodiment, the present invention discloses a water-soluble co polyester polymer, which can be used for inline or offline coating of substrate to increase their surface energy and surface adhesion.

[50] In one another embodiment, the present invention provides a water-soluble co-polyester polymer, which can be used for inline coating or offline coating of substrate provide wide range of printability performance. [51] In one another embodiment, the present invention provides a water-soluble co-polyester polymer which when inline coated on BOPET films enhance their surface properties, provides wide range of printability performance and metal to film bond strength.

[52] In one another embodiment, the present invention provides a water-soluble co-polyester polymer which when coated on metal sheets or foil (e.g. Aluminum) enhance the compatibility and hence adhesion of ink, provide wide range of printability performance.

[53] In one another embodiment, the present invention provides a water-soluble co-polyester polymer, which imparts excellent adhesion, and printability properties to the substrate when coated with the water-soluble co-polyester polymer.

[54] In one another embodiment, the present invention provides a water-soluble co-polyester polymer, which provides excellent adhesion to ink and Aluminum (metallization) when the BOPET is coated with the water-soluble co-polyester polymer. Thus, it provides wide range of printability performance over the BOPET inline coated with the co-polyester polymer of the present invention. Similarly, the inline coating of BOPET with the co-polyester polymer of the present invention also increases adhesion to Aluminum metal in the process of metallization and thus provide excellent metal to film bond strength.

[55] In one another embodiment, the present invention provides a water-soluble co-polyester polymer, which can be coated in very thin layer thickness and at very less weight gain.

[56] In one another embodiment, the present invention provides a water-soluble co-polyester polymer for substrate coating, which provides a wide range of printability performance with water-based ink systems, thus avoiding solvent-based ink systems.

[57] In one another embodiment, the present invention provides an environment friendly solution to the packaging industry.

[58] In yet another embodiment, the present method provides a process of synthesis of the water-soluble co-polyester polymer.

[59] In yet another embodiment, the present invention provides a coating composition comprising the polymer of the present invention which when coated on a biaxially oriented film the will provide excellent peelable sealable film properties including desired peal strength, minimum or negligible hazing and anti-fog properties. I. A WATER-SOLUBLE CO-POLYESTER POLYMER

[60] The present invention discloses a water-soluble co-polyester polymer; the polymer comprises a) a pre-polymer (A); and b) a pre-polymer (B); wherein, the pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol; and the pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol.

[61] The pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol.

[62] The dicarboxylic acid or ester thereof is selected from an aliphatic dicarboxylic acid, an aliphatic dicarboxylate, a cycloaliphatic dicarboxylic acid, a cycloaliphatic dicarboxylate, an aromatic dicarboxylic acid, an aromatic dicarboxylate or any combination thereof. The non limiting examples of dicarboxylic acids include isophthalic acid, dimethyl isophthalate, terephthalic acid, dimethyl terephthalate, sebacic acid, dimethyl 2,6-naphthalate, naphthalene dicarboxylic acid, dimethyl 1,4-naphthalate, succinic acid, adipic acid, azelaic acid, 2,6- naphthalene dicarboxylic acid, glutaric acid, maleic acid, fumaric acid, oxalic acid, malonic acid, pimelic acid, suberic acid or any combination thereof. Preferably, the dicarboxylic acid is selected from isophthalic acid, dimethyl isophthalate, terephthalic acid, dimethyl terephthalate or any combination thereof.

[63] In some embodiments, the dicarboxylic acid is isophthalic acid. In some embodiments, the dicarboxylic acid is terephthalic acid.

[64] In some preferred embodiments, the dicarboxylic acid is isophthalic acid.

[65] The first diol is selected from an aliphatic diol, a cycloaliphatic diol, an aromatic diol and any combination thereof. The non- limiting examples of first diols include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propaneol, butane diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, hexane diol, 1,6-hexanediol, cyclohexanedimethanol, 1,4- cyclohexanedimethanol, neopentyl glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A., bisphenol S. or any combination thereof. [66] In some embodiments, the first diol is ethylene glycol. In some embodiments, the first diol is diethylene glycol. In some embodiments, the first diol is 1,3-propanediol. In some embodiments, the first diol is cyclohexane di-methanol. In some embodiments, the first diol is a combination of diethylene glycol and cyclohexane di-methanol. In some embodiments, the first diol is a combination of ethylene glycol, diethylene glycol and cyclohexane di-methanol. In some embodiments, the first diol is a combination of cyclohexane di- methanol and 1 ,3- prop anedio le . In some embodiments, the first diol is a combination of diethylene glycol, cyclohexane di- methanol and 1,3-propanediole.

[67] In some preferred embodiments, the first diol is a combination of diethylene glycol and cyclohexane di-methanol.

[68] In some preferred embodiments, the first diol is a combination of ethylene glycol, diethylene glycol and cyclohexane di-methanol.

[69] In some preferred embodiments, the first diol is a combination of cyclohexane di methanol and 1,3-propanediole.

[70] In some preferred embodiments, the first diol is a combination of diethylene glycol, cyclohexane di- methanol and 1,3-propanediole.

[71] In some embodiments, the pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol; wherein the dicarboxylic acid is a dicarboxylic acid or a combination of dicarboxylic acids; similarly, the first diol is a first diol or a combination of first diols.

[72] In some preferred embodiments, the pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol; wherein the dicarboxylic acid is a combination of isophthalic acid; and the first diol is a combination of diethylene glycol and cyclohexane di-methanol.

[73] In some preferred embodiments, the pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol; wherein the dicarboxylic acid is a combination of isophthalic acid; and the first diol is a combination of ethylene glycol, diethylene glycol and cyclohexane di-methanol. [74] In some preferred embodiments, the pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol; wherein the dicarboxylic acid is a combination of isophthalic acid; and the first diol is a combination of cyclohexane di-methanol and 1,3-propanediole.

[75] In some preferred embodiments, the pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol; wherein the dicarboxylic acid is a combination of isophthalic acid; and the first diol is a combination of diethylene glycol, cyclohexane di-methanol and 1,3-propanediole.

[76] The pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol.

[77] The aromatic sulfonate is selected from sulfonate salts of highly reactive or transition metal e.g. Na, K, Mg, Ca, Ni, or Fe. The non-limiting examples of aromatic sulfonate includes metal salt of sodium 5-sulfophthalic acid, sulfonate isophthalic acid, sulfonate 2,6 naphthalene dicarboxylate or as disclosed in various patent documents or research papers. In some embodiments, the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester.

[78] In some preferred embodiments, the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester.

[79] The second diol is selected from the group consisting of an aliphatic diol, a cycloaliphatic diol, an aromatic diol and any combination thereof. The non-limiting examples of second diol include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propaneol, butane diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, hexane diol, 1,6-hexanediol, cyclohexanedimethanol, 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A., bisphenol S. or any combination thereof.

[80] In some embodiments, the second diol is ethylene glycol. In some embodiments, the second diol is diethylene glycol. In some embodiments, the second diol is 1,3-propane diol.

[81] In some preferred embodiments, the second diol is ethylene glycol.

[82] In some preferred embodiments, the second diol is diethylene glycol. [83] In some preferred embodiments, the second diol is 1,3-propane diol.

[84] In some preferred embodiments, the second diol is cyclohexane di-methanol.

[85] In some embodiments, the pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol; wherein the aromatic sulfonate an aromatic sulfonate or a combination of more than one aromatic sulfonates; similarly, the second diol is a second diol or a combination of more than one second diols.

[86] In some preferred embodiments, the pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol; wherein the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester; and the second diol is ethylene glycol.

[87] In some preferred embodiments, the pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol; wherein the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester; and the second diol is diethylene glycol.

[88] In some preferred embodiments, the pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol; wherein the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester; and the second diol is 1,3-propane diol.

[89] In some preferred embodiments, the pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol; wherein the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester; and the second diol is cyclohexane di-methanol.

[90] It is understood that each description of dicarboxylic acid may be combined with each description of the first diol the same as if each and every combination were specifically and individually listed. Similarly, it is understood that each description of aromatic sulfonate may be combined with each description of the second diol the same as if each and every combination were specifically and individually listed. It is similarly understood that each description of pre polymer (A) (each description of the dicarboxylic acid with each description of the first diol) may be combined with each description of pre-polymer (B) (each description of the aromatic sulfonate with each description of the second diol).

[91] The water-soluble co-polyester polymer disclosed herein are used to coat one or more substrates. The substrates include but not limited to BOPET film, BOPET primer for metallization, Aluminum sheets (preferably Aluminum sheets used to manufacture Aluminum can) and biaxially oriented film for peelable sealable packaging.

[92] The polymer of the present invention can be coated on the BOPET film during inline manufacturing process. The coating can also be done offline while coating on Aluminum sheets.

[93] The polymer of the present invention imparts excellent surface characteristics to the coated surface e.g. surface energy, adhesion, printability, metal to film bond strength etc. The polymer of the present invention also coats the surface very efficiently in minimum weight gain. The polymer of the present invention also imparts minimum hazing and excellent anti- fog properties for peelable sealable packaging.

[94] The surface coated with the polymer disclosed in the present invention can be printed using a wide range of ink systems e.g. water-based inks and solvent-based ink system. The polymer of the present invention is also used with the UV curable inks to coat the surface of the substrates.

[95] The polymer of the present invention exhibits an intrinsic viscosity (I.V.) from about 0.3 to 0.6 dL/g. Preferably, the polymer of the present invention exhibits an intrinsic viscosity (I.V.) from about 0.35 to 0.6 dL/g. More preferably, the polymer of the present invention exhibits an intrinsic viscosity (I.V.) from about 0.35 to 0.55 dL/g.

[96] The polymer of the present invention exhibits a carboxylic content from 70 to 100 meq/Kg. Preferably, the polymer of the present invention exhibits a carboxylic content from 75 to 95 meq/Kg. More preferably, the polymer of the present invention exhibits a carboxylic content from 80 to 90 meq/Kg.

[97] The polymer of the present invention exhibits a glass transition temperature from 50 °C to 60 °C. Preferably, the polymer of the present invention exhibits a glass transition temperature from 50 °C to 55 °C. Preferably, the polymer of the present invention exhibits a glass transition temperature from 55 °C to 60 °C.

[98] The polymer of the present invention when coated over a 12 micron BOPET film in inline manufacturing process, the coating is done at a coating thickness from 0.01 to 0.09 GSM. Preferably, the coating is done at a coating thickness from 0.02 to 0.08 GSM. More preferably, the coating is done at a coating thickness from 0.02 to 0.07 GSM.

[99] The polymer of the present invention when coated over a 12 micron BOPET film at a coating thickness from 0.01 to 0.09 GSM and then the coated BOPET film is printed, the coated and printed BOPET film exhibits resistance to ink adhesion test in Tape Test after sustaining boiling water test for 0.5 to 2 hr. Preferably, the coated and printed BOPET film exhibits resistance to ink adhesion test in Tape Test after sustaining boiling water test for 1 hr. More preferably, the coated and printed BOPET film exhibits resistance to ink adhesion test in Tape Test after sustaining boiling water test for 0.5 hr.

[100] The polymer of the present invention when coated over a 12 micron BOPET film at a coating thickness from 0.01 to 0.09 GSM, then the coated BOPET film is vacuum metallized with an optical density from 0.5 to 3.2. Preferably, the coated BOPET film is vacuum metallized with an optical density from 1.5 to 3.2. More preferably, the coated BOPET film is vacuum metallized with an optical density from 1.8 to 3.2.

[101] The polymer of the present invention when coated over a 12 micron BOPET film at a coating thickness from 0.01 to 0.09 GSM and then the coated BOPET film is metallized with Aluminum; the coated and metallized BOPET film exhibits a metal to film bond strength from 350 g/inch to 700 g/inch. Preferably, the coated and metallized BOPET film exhibits a metal to film bond strength from 400 g/inch to 650 g/inch. More preferably, the coated and metallized BOPET film exhibits a metal to film bond strength from 450 g/inch to 600 g/inch.

II. PROCESS OF SYNTHESIS OF WATER-SOLUBLE CO-POLYESTER POLYMERS

[102] The present invention also discloses a process of synthesis of a water-soluble co polyester polymer.

[103] The present invention discloses a process of synthesis of a water-soluble co-polyester polymer; the process comprising polymerizing a) a pre-polymer (A); and b) a pre-polymer (B); wherein, the pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol; and the pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol. [104] In another way, the present invention discloses a process of synthesis of a water-soluble co-polyester polymer; the process comprising the steps of: a) synthesizing a pre-polymer (A); b) synthesizing a pre-polymer (B); and c) polymerizing the pre -polymer (A) and the pre polymer (B); wherein, the pre-polymer (A) comprises a transesterification reaction product of a dicarboxylic acid or ester thereof with a first diol; and the pre-polymer (B) comprises a reaction product of an aromatic sulfonate with a second diol.

A. Synthesis of Pre-polymer (A)

[105] The pre-polymer (A) is synthesized by carrying out transesterification reaction between a dicarboxylic acid and a first diol.

[106] The dicarboxylic acid and the first diol may be one dicarboxylic acid and one diol; or can be a mixture of dicarboxylic acids and diols.

[107] The dicarboxylic acid or ester thereof is selected from an aliphatic dicarboxylic acid, an aliphatic dicarboxylate, a cycloaliphatic dicarboxylic acid, a cycloaliphatic dicarboxylate, an aromatic dicarboxylic acid, an aromatic dicarboxylate or any combination thereof. The non limiting examples of dicarboxylic acids include isophthalic acid, dimethyl isophthalate, terephthalic acid, dimethyl terephthalate, sebacic acid, dimethyl 2,6-naphthalate, naphthalene dicarboxylic acid, dimethyl 1,4-naphthalate, succinic acid, adipic acid, azelaic acid, 2,6- naphthalene dicarboxylic acid, glutaric acid, maleic acid, fumaric acid, oxalic acid, malonic acid, pimelic acid, suberic acid or any combination thereof. Preferably, the dicarboxylic acid is selected from isophthalic acid, dimethyl isophthalate, terephthalic acid, dimethyl terephthalate and any combination thereof.

[108] In some embodiments, one dicarboxylic acids is used. In some embodiments, the dicarboxylic acids are used in mixture. In one embodiment, the dicarboxylic acids are selected from aromatic dicarboxylic acid. In one embodiment, the dicarboxylic acids are selected from dimethyl terephthalate, pure terephthalate, isophthalic acid, ortho-phthalic acid, dimethyl 2,6- naphthalate and naphthalene di-carboxylic acid. The aromatic di-carboxylic acids used 1 to 100 mole% or more precisely 5- 60 mole %.

[109] The first diol is selected from ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,3- butanediol,l,4-butanediol,l,5-pentanediol,l,6-hexanediol, neopentyl glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol and 1,4- cyclohexanedimethanol. The first diol used are linear aliphatic, branched aliphatic di-ol or alicyclic di- hydroxy compound glycol at 5 to 50 mole%, specially 2 to 80 mole % with mono ethylene glycol content from 1 to 100 molepercentage or 10 to 80 mole%.

[110] The transesterification reaction is carried out in presence of one or more catalyst. The catalyst system is selected from Antimony trioxide and Titanium-based catalyst; preferably, the catalyst is Antimony trioxide. The catalyst is used in monomer slurry at a concentration ranging from 1 to 1000 ppm; preferably, from 10 to 600 ppm.

[111] The transesterification reaction is carried out in presence of one or more heat stabilizer. The heat stabilizer is selected from ortho phosphoric acid or poly phosphoric acid; preferably poly phosphoric acid from 1 to 1000 ppm; more preferably from 10 to 600 ppm.

[112] The temperature of the transesterification reaction is maintained from 200 C to 300 C; preferably from 240 C to 280 C.

[113] For synthesis of pre-polymer (A) the transesterification reaction is carried out from 2 to 5 hr; preferably from 2 to 4 hr. The catalyst and heat stabilizer added in slurry mixture. After transesterification was complete, which was confirmed by removal of quantity of water.

B. Synthesis of Pre-polymer (B)

[114] The pre-polymer (B) is synthesized by carrying out reaction between an aromatic sulfonate dicarboxylic acid and a second diol.

[115] The aromatic sulfonate is selected from sulfonate salts of highly reactive or transition metal e.g. Na, K, Mg, Ca, Ni, or Fe. The non-limiting examples of aromatic sulfonate includes metal salt of sodium 5-sulfophthalic acid, sulfonate isophthalic acid, sulfonate 2,6 naphthalene dicarboxylate or as disclosed in various patent and non-patent documents. In some embodiments, the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester.

[116] In one preferred embodiments, the aromatic sulfonate is 5-sulphoisophtalic acid, monosodium salt, dimethyl ester.

[117] The second diol is selected from the group consisting of an aliphatic diol, a cycloaliphatic diol, an aromatic diol and any combination thereof. The non-limiting examples of second diol include ethylene glycol, diethylene glycol, 1,2-propanediol, 1,3-propaneol, butane diol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, hexane diol, 1,6-hexanediol, cyclohexanedimethanol, 1,4-cyclohexanedimethanol, neopentyl glycol, diethylene glycol, polyethylene glycol, polypropylene glycol, polytetramethylene glycol, bisphenol A., bisphenol S. or any combination thereof.

[118] In some embodiments, the second diol is ethylene glycol. In some embodiments, the second diol is diethylene glycol. In some embodiments, the second diol is 1,3-propane diol. In some embodiments, the second diol is cyclohexanedimethanol.

[119] In one preferred embodiment, the second diol is ethylene glycol. [120] In one preferred embodiment, the second diol is diethylene glycol.

[121] In one preferred embodiment, the second diol is 1,3-propane diol.

[122] In one preferred embodiment, the second diol is cyclohexanedimethanol.

[123] The sulfonated pre-polymer (B) is synthesized as per the process disclosed in the PCT Application No. WO2015124959A1. C. Polymerization of Pre-polymer (A) and Pre-polymer (B)

[124] The process of synthesizing water soluble co-polyester polymer of the present invention; the process comprises polymerizing the pre-polymer (A) and pre-polymer (B).

[125] The pre-polymer (A) and pre-polymer (B) were taken in a Wt. % from 1 to 90% by w/w and 5 to 60% by weight respectively. [126] The polymerization reaction is carried out in negative pressure, preferably in vacuum.

[127] The polymerization is carried out in the presence of one or more catalyst.

[128] The polymerization reaction was carried out for about 2 to 4.5 hr; preferably 2 to 4 Hr.

[129] The temperature of the polymerization reaction was maintained from 220 C to 350 C; preferably, from 230 C to 290 C. [130] The process of synthesis disclosed in the present invention wherein the polymer synthesized by the process is used to coat one or more substrates. The substrates include but not limited to BOPET film, BOPET primer for Aluminum metallization and Aluminum sheets.

[131] The process of synthesis disclosed in the present invention wherein the polymer synthesized by the process can be coated on the BOPET film during inline manufacturing process. The coating can also be done offline while coating on Aluminum sheets.

[132] The process of synthesis disclosed in the present invention wherein the polymer synthesized by the process imparts excellent surface characteristics to the coated surface e.g. surface energy, adhesion, printability, metal to film bond strength etc. The polymer of the present invention also coats the surface very efficiently in minimum weight gain.

[133] The process of synthesis disclosed in the present invention wherein the polymer synthesized by the process can be printed using a wide range of ink systems e.g. water-based inks and solvent-based ink system. The polymer of the present invention is also used with the UV curable inks to coat the surface of the substrates.

[134] The polymer synthesized by the process disclosed herein exhibits an intrinsic viscosity (I.V.) from about 0.3 to 0.6 dL/g. Preferably, the polymer exhibits an intrinsic viscosity (I.V.) from about 0.35 to 0.6 dL/g. More preferably, the polymer exhibits an intrinsic viscosity (I.V.) from about 0.35 to 0.55 dL/g.

[135] The polymer synthesized by the process exhibits a carboxylic content from 70 to 100 meq/Kg. Preferably, the polymer exhibits a carboxylic content from 75 to 95 meq/Kg. More preferably, the polymer exhibits a carboxylic content from 80 to 90 meq/Kg.

[136] The polymer synthesized by the process disclosed herein exhibits a glass transition temperature from 50 °C to 60 °C. Preferably, the polymer exhibits a glass transition temperature from 50 °C to 65 °C. Preferably, the polymer exhibits a glass transition temperature from 55 °C to 60 °C.

[137] The polymer synthesized by the process disclosed herein when coated over a 12 micron BOPET film in inline manufacturing process, the coating is done at a coating thickness from 0.01 to 0.09 GSM. Preferably, the coating is done at a coating thickness from 0.02 to 0.08 GSM. More preferably, the coating is done at a coating thickness from 0.02 to 0.07 GSM. [138] The polymer synthesized by the process disclosed herein when coated over a 12 micron BOPET film at a coating thickness from 0.01 to 0.09 GSM and then the coated BOPET film is printed, the coated and printed BOPET film exhibits resistance to ink adhesion test in Tape Test after sustaining boiling water test 0.5 to 2 hr. Preferably, the coated and printed BOPET film exhibits resistance to ink adhesion test in Tape Test after sustaining boiling water test for 1 hr. More preferably, the coated and printed BOPET film exhibits resistance to ink adhesion test in Tape Test after sustaining boiling water test for 0.5 hr.

[139] The polymer synthesized by the process disclosed herein when coated over a 12 micron BOPET film at a coating thickness from 0.01 to 0.09 GSM, then the coated BOPET film is metallized with Aluminum with an optical density from 0.5 to 3.2. Preferably, the coated BOPET film is metallized with Aluminum with an optical density from 1.5 to 3.2. More preferably, the coated BOPET film is metallized with Aluminum with an optical density from 1.8 to 3.2.

[140] The polymer synthesized by the process disclosed herein when coated over a 12 micron BOPET film 0.01 to 0.09 GSM and then the coated BOPET film is vacuum metallized with Aluminum exhibits a metal to film bond strength from 350 g/inch to 700 g/inch. Preferably, the metallized film exhibits a metal to film bond strength from 400 g/inch to 650 g/inch. More preferably, the metallized film exhibits a metal to film bond strength from 450 g/inch to 600 g/inch.

III. PROCESS OF SYNTHESIS OF WATER-SOLUBLE CO-POLYESTER POLYMERS

[141] The present invention also discloses a coating composition comprising the polymer of the present invention from 5 to 20 %; a water based polyurethane dispersion (PUD) from 15 to 35 %; a cross-linking agent from 2 to 5 %; a catalyst from 0.1 to 0.3 %; an anti- fog agent from 0.5 to 2 %; ethyl acetate from 4 to 8 % and water to make the volume 100 %.

[142] The water-based polyurethane dispersion (PUD) used in the coating composition of the present invention is Joncryl FLX 5201.

[143] The cross-linking agent used in the coating composition of the present invention is preferably melamine cross-linking agent. The melamine cross-linking agent used in the present invention is AMIDIR PM-80. [144] The catalyst used in the coating composition of the present invention is Catalyst PTS.

[145] The anti- fog agent used in the coating composition of the present invention is Atmer- 116.

[146] The coating composition of the present invention when coated over a 12 to 75 micron BOPET film at a coating thickness from 0.08 to 3.0 GSM and then the coated BOPET film is heat sealed to a A-PET, C-PET, G-PET or PVDC trays; the coated and sealed BOPET film exhibits a peal strength from 450 to 1500 gm/inch; preferably a peal strength from 450 to 1200 gm/inch; more preferably, a peal strength from 450 to 1100 gm/inch.

[147] The coating composition of the present invention when coated over a 12 to 75 micron BOPET film at a coating thickness from 0.08 to 3.0 GSM and then the coated BOPET film is heat sealed to a A-PET, C-PET, G-PET or PVDC trays; the coated and sealed BOPET film exhibits an increasing in hazing is from 0.25 to 1 %; preferably an increasing in hazing is from 0.25 to 0.75%; more preferably, an increasing in hazing is from 0.25 to 0.50%.

[148] The coating composition of the present invention when coated over a 12 to 75 micron BOPET film at a coating thickness from 0.08 to 3.0 GSM and then the coated BOPET film is heat sealed to a water filled A-PET, C-PET, G-PET or PVDC trays and stored at 4 °C; the peelable sealable film exhibits no or negligible cold fog.

[149] The coating composition of the present invention when coated over a 12 to 75 micron BOPET film at a coating thickness from 0.08 to 3.0 GSM and then the coated BOPET film is heat sealed to a water filled A-PET, C-PET, G-PET or PVDC trays and heated at 60 °C; the peelable sealable film exhibits no or negligible hot fog for atleast 3 hours.

General Procedures

[150] Synthesis of Water Soluble Co-Polyester Polymer:

Procedure

[151] Step: 1: Synthesis of Pre-polymer (A): Dicarboxylic acids and diols were taken together in a reactor vessel. The catalyst Antimony Trioxide and heat stabilizer poly phosphoric acid were added in a concentration ranging from 10-600 ppm and 10-600 ppm respectively. The reactants were allowed to react for about 2 to 3.5 Hr at a temperature ranging from 240 °C to 280 °C. The reaction completion was validated by the removal of water.

[152] Step: 2: Synthesis of sulfonated Pre-polymer (B): Sulfonated pre-polymer was synthesized as disclosed in various publications and patent documents. The sulfonated pre- polymer was synthesized by the method disclosed in PCT Published Application No. WO2015124959A1 (Kulkarni etal.).

[153] Step: 3: Synthesis of Polymer:

[154] The pre-polymer (A) and pre-polymer (B) were added in a reactor vessel. The vacuum was applied to the reaction. Then, the pre-polymers were allowed to react for about 2.5 to 4 hr at a temperature ranging from 230 °C to 290 °C.

[155] Typical formula of the polymer of the present invention are given in table-1. Different polymers were synthesized through general procedures given herein.

Table-1: Formulation of typical examples of the polymer of the present invention [156] For formula 1, isophthalic acid was taken as carboxylic acids; ethylene glycol was taken as the first diol. 5-sulphoisophtalic acid, monosodium salt, dimethyl ester was taken as aromatic sulfonate and diethylene glycol and cyclohexanedimethanol were taken as the second diol. For formula 2, isophthalic acid was taken as carboxylic acids; ethylene glycol was taken as the first diol. 5-sulphoisophtalic acid, monosodium salt, dimethyl ester was taken as aromatic sulfonate and ethylene glycol, diethylene glycol and cyclohexanedimethanol were taken as the second diol. For formula 3, isophthalic acid was taken as carboxylic acids; cyclohexanedimethanol was taken as the first diol. 5-sulphoisophtalic acid, monosodium salt, dimethyl ester was taken as aromatic sulfonate and diethylene glycol and cyclohexanedimethanol were taken as the second diol. For formula 4 and 5, isophthalic acid was taken as carboxylic acids; cyclohexanedimethanol was taken as the first diol. 5-sulphoisophtalic acid, monosodium salt, dimethyl ester was taken as aromatic sulfonate and diethylene glycol, 1,3 -propanediol and cyclohexanedimethanol were taken as the second diol.

[157] Different batches of the polymer of the present inventions were synthesized and evaluated. The evaluation characteristics of the polymers synthesized, coated PET film, vacuum metallized BOPET film and composite film are given in tables 2-5.

D. Coating of the Present Polymer on BOPET Film

(i) Preparation of Coating Solution:

[158] A 5 to 25 % solution of polymer of the present invention is prepared by dissolving in hot water at 90 °C with agitation with a water-cooled condenser tank for about 1 to 3 hr. The polymer of the present invention was dissolved completely without leaving any undissolved residue or leaving negligible residue. The solution was cooled down to room temperature and filtered with 10 to 40 micron filter mesh. A melamine formaldehyde crosslinking agent (Cymel 303LF) with 0.5 to 10% weight % or more precisely from 1 to 5 weight % and a catalyst (Cycate 4045) ranging from 0.1 to 4 weight %, more precisely 0.2- 1.0 weight % was added in final solution mixture.

(ii) Coating of BOPET Films

[159] BOPET films were coated with the solution of the polymer of the present invention by inline polyester film manufacturing after machine direction orientation and before transverse direction orientation. The coated with films were further subjected to transverse orientation with crystallization and drying process at temperature range of 80 C to 240 C with 1.5 to 5 times stretching. Polymers of the present invention were coated with horizontal gravure kiss coating system during manufacturing of BOPET films. The coating thickness maintained from 0.01 to 0.09 GSM.

E. Preparation of Coating Composition of the present invention Peelable Sealable BOPET film Coating. [160] A 5 to 20% solution of the polymer of the present invention was prepared. A Water base polyurethane dispersion (PUD) (Joncryl FLX 5201) was added to it (15 to 35 %). Melamine type cross linker (AMIDIR PM-80) was added to it in about 2 to 5%. A catalyst was also used (Catalyst PTS) (0.1 to 0.3 %). Atmer-116 was added as an anti- fog agent (0.5-2%); and ethyl acetate (4-8%). The solution prepared exhibits total solid of 20 to 30% and Viscosity (B4-Ford cup) of 10 to 20. The pH range was maintained at 7+0.5.

F. Coating and Hot Sealing of Peelable Sealable Biaxially Oriented Film Coated with the Polymer of the Present Invention

[161] The coating solution was coated inline and off line on BOPET film at GSM ranging 0.08 to 3. The BOPET film used in this example is 23 micron. However, the said applications are also performed with thickness range of BOPET from 12 to 75 micron. Here to mention that, if the off line coating on BOPET substrate is done on primed BOPET film, the excellent results are obtained. The tray used in this example are 200 to 500 micron A-PET, C-PET, PET-G and PVDC. The temperature range of sealing is from 130 -180 °C at 40 - 80 PSI pressure and a dwell time of 0.5 to 2 second.

III. EVALUATIONS

[162] The water-soluble co-polyester polymers disclosed herein were synthesized and evaluated for various quality characterstics. These character sties includes intrinsic viscosity (I.V.), carboxylic end group content, glass transition temperature (T _g ), tensile strength, thermal shrinkage, haze, sufrace energy, co-efficient of friction, coating thickness, boiling test for ink removal, metallization efficiency, optical density, metal to film bond strength, water vapour transmission rate (WVTR) and oxygen transmission rate (OTR). Average test results are given in the tables 2 to 5.

A. Evalutation of Water-Soluble Co-polyester Polymer

(i) Intrinsic Viscosity (I.V.):

[163] Intrinsic viscosity was measured by dissolving 0.25+0.002 co-polyester polymer in a solvent system of Phenol and 1, 1,2,2 tetrachloro ethane (60:40 w/w) using Ubbelohde capillary viscometer. The results for water soluble polymers synthesized as per the present invention are given given in table-2. (ii) Carboxylic End Group (-COOH) Content:

[164] Carboxylic end group content measurement was done using approximate 1.0+0.02 g of co-polyester dissolved in solvent system Phenol: Chloroform (50:50 w/w). The resultant solution was titrated with 0.02 N Benzyl- KOH. Approx. 4 drops of bromophenol blue were used as indicator. The results for water soluble polymers synthesized as per the present invention are given given in table-2.

(iii) Glass Transition Temperature (T _g ):

[165] Glass transition temperature (T _g ) was measured by differential scanning calorimetry (DSC). The results for water soluble polymers synthesized as per the present invention are given given in table-2.

(iv) Colour Test:

[166] Color was tested by using HunterLab® apparatus. The results for water soluble polymers synthesized as per the present invention are given given in table-2.

Table-2: Evaluation results for the polymer disclosed in the present invention

B. Evalutation of 12 micron BOPET Film Inline Coated with Polymers of the Present Invention.

(i) Tensile Strength: [167] The tensile properties were measured by using universal tensile testing machine (UTM) as per ASTM D882. The results given given in table-3.

(ii) Thermal Shrinkage:

[168] Thermal shrinkage of film was measured according to ASTM D2838, where in samples were cut in required sizes (254 mm x 254 mm), initial dimensions were measured and marked as Machine Direction (MD) and Transverse Direction (TD) on the sample, which were placed in an oven at 150 C for 30 min. The sample were taken out after 30 min. and allowed to cool at room temperature. The final dimensions of sample were measured again to check the shrinkage. The results are given given in table-3.

(iii) Haze and Transmittance:

[169] Haze % and transmittance % of the film is measured by using a Haze meter or by a spectrophotometer, according to ASTM D1003. The results are given in table-3.

(iv) Surface Energy:

[170] Surface energy was tested as per the ASTM D 2578 standard. The results are given given in table-3.

(v) Co-efficient of friction:

[171] The co-efficient of friction was tested as per the ASTM D 1894 standard. The results are given given in table-3.

(vi) Coating Thickness:

[172] Coating thickness was measured by gm/m ² . In order to determine coating thickness, samples were cut in the size of 100 x 100 mm templates and their weight were measured using weighing balance having accuracy of 0.001 gm. Thereafter, the coating of the film was removed by suitable solvent and the samples are weighed again. The difference of weight of the sample was used to measure coating thickness using following formula. Average GSM = (weight difference of sample in gm) / (length in meter x width in meter). The results are given given in table-3.

(vii) Ink-adhesion Test (Tape Test): [173] The coated films were printed with one to six colors in a conventional gravure printing machine using solvent-based ink. The printed films were then kept on a glass container at 90 to 100 C in boiling water for about 2 hr. Then the films were dried and checked for tape test using 3M tape number 610 for ink adhesion test. A conventional corona treated BOPET film was also carried out for the same test. The results are given given in table-3.

Table-3: Evaluation results for the 12 micron BOPET coated with the polymer disclosed in the present invention

C. Evalutation of 12 micron BOPET film inline coated with polymers (0.010 to 0.090 GSM) then vacuum metallized with Aluminum metal

(i) Optical Density:

[174] Optical density was measured using Tobias instrument. The results are given given in table-4.

(iii) Metal to film bond strength: [175] Metal to film bond strength was measured by AIMCAL standard. The results are given given in table-4.

(iv) Water Vapor Transmission Rate (WVTR):

[176] Water Vapor Transmission Rate (WVTR) of metallized film was evaluated as per ASTM F372 by using MOCON PERMATRAN 3/33 at the test condition of 38 ^° C and 90% RH

(Relative Humidity). The results are given given in table-4.

(v) Oxygen Transmission Rate (OTR):

[177] Oxygen transmission rate (OTR) of metallized film was evaluated according to ASTM D 3985 using Mocon OX-TRAN® 2/21 instrument at test condition of 23 C and 0% Relative Humidity (RH). The results are given given in table-4.

Table-4: Evaluation results for the 12 micron BOPET coated with the polymer then metallized with Aluminum

D. Evalutation of 23 micron BOPET film inline coated with Coating Composition of the Present Invention (0.08 to 0.30 GSM) then hot sealed on A-PET, C-PET, G-PET or PVDC tray

(i) Peel Strength:

[178] Peel strength was tested. Results are given in table-5. (ii) Cold Fog Test: [179] This test simulates the AF-performance of a film, which is used for a packaging system for food stored in a fridge. A 250 ml beaker was filled with water about 200 ml. The top of the beaker was covered with the biaxially oriented film coated with the polymer of the present invention. The beaker was placed in temperature-controlled cabinet at 4°C. The beaker was observed till one week for cold fog. Results are given in table-5.

(iii) Hot Fog Test:

[180] This test simulates the AF-performance of a film, which is used for a packaging system in which hot food is filled, which is than stored in a closed container in a fridge. A 250 ml beaker filled with 50 ml water and covered the top of the beaker with a coated biaxially oriented film. The beaker was placed in the water bath and heated at 60 °C for 3 hr. Results are given in the table- 5. Table-5: Evalutation of 23 micron BOPET film inline coated with Coating Composition of the Present Invetnion (0.08 to 3.0 GSM) then hot sealed on A-PET, C-PET, PET-G or PVDC tray

IV. OBSERVATION AND CONCLUSION [181] The results showed that the polymer of the present invention coated the substrates

BOPET films in very less weight gain (very less GSM) i.e. 0.01 to 0.09 GSM. Further, the metal to film bond strength offered by the polymer of the present invention was very strong. The polymer of the present invention also showed excellent printability with boiling water resistance. The polymer of the present invention can be used for inline coating BOPET films and for BOPET film primer for metallization. The most important thing is that the polymer of the present invention can be used with water-based ink systems as well as solvent-based ink systems for printability.

[182] The coating composition of the present invention is also good for preparing peelable sealable film with anti- fog properties. The most important thing is that the coating composition of the of the present invention is water-based.

[183] The present description is the best presently-contemplated system and method for carrying out the present invention. Various modifications to the preferred embodiment will be readily apparent to those skilled in the art and the generic principles of the present invention may be applied to other embodiments, and some features of the present invention may be used without the corresponding use of other features. Accordingly, the present invention is not intended to be limited to the embodiment shown but is to be accorded the widest cope consistent with the principles and features described herein.