FIELD OF THE INVENTION:
The present invention relates to a one-component, hybrid polyurethane resin binder suitable for printing inks applied on polymeric substrates for high boil and high retort applications, more specifically the printing inks exhibit high boil and high retort resistance, excellent printability, excellent lamination strength with either solvent base or solvent-free adhesives and better extrusion lamination bond strength properties when laminated with polyethylene (PE), polypropylene (PP) film substrates metallized BOPP, CPP etc..
BACKGROUND OF THE INVENTION:
In order to provide superior aesthetic appeal and good physical characteristics to printed films, gravure and flexographic printing are widely used. Also, the polyurethane base binders usually contain free isocyanates and are soluble in aromatic hydrocarbon solvents. Aromatic hydrocarbon solvents-based printing inks pose several environmental hazards as releasing a large amount of volatile organic compounds (VOC) to the atmosphere, and in order to meet the environmental standards as a duty of every printing ink and packaging industry, the disposal of the these solvents is a big concern. Also these solvents and isocyanates used to synthesise polyurethanes pose several health hazards to the working personnel. In view of safeguarding the environment and health of the working personnel, the regulations imposed on the printing industries in the recent times has prompted the printing processes to resort to aromatic hydrocarbon free printing inks.
In the last two decades, printing ink industries care well for the environmental concerns, and are determined to use non-aromatic, especially non-toluene solvents, in order to reduce the amount of environmentally hostile residual solvents, yet, meeting the challenges of increasing the solubility of the ink binders in toluene-free solvents. Improvement in the synthesis of polyurethane (PU) resins has been the key behind increasing the solubility, specifically for the inks used for lamination articles. Appropriate selection of polyol type including the type of polyol, and molecular weight of these different types of polyols (e.g. polyester polyol, polyether polyol) play important roles in deriving new non-toluene solvent soluble polyurethanes.
Also in the synthesis of PU, the ratio of the different types of polyols and the diisocyanate used as the PU raw materials and the polyamine used as the chain extender play a vital role on the structure of the final PU binder as well as the molecular weight of the final PU, which pave the way for better ink formulation, in

terms of the different required physical properties of the printed films with the innovative printing inks.
Specifically, printing inks for lamination require superior boiling and retort resistance when they are used in high cooking or sterilization processes. In addition, the printing inks require excellent re-solubility in alcohol and ester solvents, and when printed on substrates/films, the printing inks need to show good adhesion to substrate it is printed on, good printability, excellent blocking resistance, quick drying, and required lamination bond strength.
It is further important to provide a suitable "one-component binder" in the above discussed context, which is appropriate for formulating printing inks that exhibit high boil and retort properties.
The existing printing inks used in printed packaging films for high boil and retort applications have poor printability concerns when they undergo high cooking or sterilization process. In such situations, additional two-component hardeners need to be added to achieve the desired properties which increase the cost of the printing inks. Further, the press return inks were either discarded, or in order to make them reusable, sufficient amount of the hardener was added to those inks again.
US9738808B2 discloses an inkjet ink that includes an anionic polyurethane (PU) acrylic hybrid polymer, wherein the anionic polyurethane polymer includes the components as A a polyisocyanate, B a polyol having a number average molecular weight (Mn) from about 500 to about 6,000, (c) a compound containing an ionic group or a group capable of forming an ionic group, (d) optionally a polyol having a polyethyleneoxide functional group, and (e) optionally a diol or triol having a number average molecular weight (Mn) ranging from about 62 to about 500. The produced polyurethane has a molecular weight of 5,000 to 70,000.
US6642343B2 discloses a polyurethane (PU) resin, which is soluble in organic solvents, is the product of at least one diisocyanate and a component having isocyanate reactive functional groups which include a first polyol group having an average molecular weight from 1000 to 10000 g/mol, a second polyol group having an average molecular weight from 10000 to 20000 g/mol, and a third polyol group having an average molecular weight not greater than 800 g/mol. The equivalent ratio of the diisocyanate to the components having isocyanate reactive functional groups is such that the resulting polyurethane resin has no unreacted polyisocyanate. The

produced polyurethane has a molecular weight of 20,000 to 80,000.
US5556925A discloses a polyurethane resin which is a reaction product of a high molecular weight polyol compound having a molecular weight of 3,000 to 10,000, a low molecular weight polyol compound having a molecular weight of not more than 200, an organic diisocyanate compound, a chain extender, and optionally a reaction terminating agent, wherein the whole of the high molecular weight polyol compound and the low molecular weight polyol compound has an average molecular weight of 1,500 to 2,700. The produced polyurethane has a molecular weight of 1500 to 27000.
Patent Applications US2019322887A1, US2019315987A1, EP3532550A1 from Hewlett Packard disclose inkjet ink compositions that comprise of a polyurethane binder which is formed by reacting a polyisocyanate; a first polyol having a chain with two hydroxyl functional groups at one end of the chain and no hydroxyl groups at an opposed end of the chain; a second polyol having a chain with two hydroxyl functional groups at both ends of the chain. The first polyol has a number average molecular weight (Mn) ranging from about 500 g/mol to about 5000 g/mol; and the second polyol(s) can have a number average molecular weight (Mn) of about 500 g/mol to about 3000 g/mol. In US2019322887A1 and EP3532550A1, the PU molecular weight achieved is 15,000 to 120,000, while in US2019315987A1, the polyurethane molecular weight achieved is 10,000 to 100,000.
AU2002231758A1 discloses a polyurethane resin (soluble in organic solvents, preferably in alcohols) for printing ink compositions is the reaction product of diisocyanate components having isocyanate reactive functional groups, said components comprising a first group of polyols, a second group of polyols and a third group of polyols, wherein first group polyols are of an average molecular weight of 1000 to 10000 g/mol wherein second group polyols are of an average molecular weight in excess of 10000 up to 20000 g/mol; and the third group polyols are of an average molecular weight of equal or less than 800 g/mol. The produced Polyurethane has a molecular weight of 20,000 or 80,000.
US9701855B2 discloses an oil-based printing ink varnish comprising a polyurethane prepared using a polymeric polyol and a polyisocyanate as the main structural components, wherein the polyurethane is synthesized using, as a chain extender, a polyfunctional amine which contains at least one secondary amino group in each molecule and in which the total of the number of primary amino groups and the number of secondary amino groups is 3 or more per molecule. The Polyurethane

(PU) includes a polyester polyol of molecular weight 500 to 10000, and a polyether polyol of molecular weight 700 to 3000, and the PU molecular weight is 10,000 to 100,000.
US7067607B2 discloses a polyurethane resin which is the reaction product of at least one diisocyanate and a group of components having isocyanate reactive functional groups. The group of components includes a first group of one or more polyether polyols each having an average molecular weight in the range of 1000 to 10000 g/mol, a second group of one or more polyether polyols each having an average molecular weight in the range of 400 to 10000 g/mol and being hydrophilic and water-soluble, a third group of one or more polyols each having an average molecular weight equal to or less than 800 g/mol. The produced PU has a molecular weight of 10,000 or 80,000.
US2009082518A1 discloses a carboxyl group-containing polyurethane (PU) produced from a polyol B containing at least 10 mol % (relative to the total (100 mol %) of the polyol B) of a polyol (b1) which: (i) has a number-average molecular weight of 500 to 50,000; (ii) has 1 to 10 hydroxyl groups per molecule; and (iii) is one or a combination of two or more polyols selected from the group consisting of polybutadiene polyol, polyisoprene polyol, hydrogenated polybutadiene polyol and hydrogenated polyisoprene polyol. The produced PU has a molecular weight of 1,000 or 200,000.
US2005148686A1 discloses a polyurethane comprising a first group of one or more polyether polyols each having an average molecular weight in the range of between 400 to 12000 g/mol, a second group of one or more polyhydroxylated resins selected from the group consisting of ketonic resins, polyester resins, acrylic-styrene copolymers, acrylic polyols, rosin derivatives and terpene-phenolic resins, optionally a third group of one or more polyols each having an average molecular weight of equal or less than 800 g/mol.
JPH0798855B2 discloses a polyurethane-polyurea ink binder resin obtained by subjecting a terminal isocyanate prepolymer obtained by reacting a two-functional polyol with a diisocyanate compound, wherein a first group of polyester polyols have a molecular weight of 1500-2500, and a second group of polyester polyols have a molecular weight of 300-500. The produced ink binder resin has a molecular weight of 15,000 or 100,000.

JP6558033B2 discloses an alcohol-soluble binder for printing ink which contains a polyurethane polymer formed by reaction of high-molecular polyol, low-molecular polyol, a hydrophilic resin, and a polyisocyanate compound without a solvent, where a number average molecular weight of the high-molecular polyol to be used is 500-4,000, and the low-molecular polyol to be used is saturated or unsaturated low-molecular polyol having 9 or less carbon atoms and is contained in an amount of 1-10 mass% to the polyurethane resin. The hydrophilic resin is polyethylene glycol having a number average molecular weight of 500 to 2,000. The produced ink binder resin has a molecular weight of 5,000 or 100,000.
JP5523744B2 discloses a binder for printing ink, the polyurethane resin is obtained by reacting a high-molecular polyol with a number average molecular weight of 5,000 to 10,000, a low-molecular-weight polyol with a molecular weight of less than 1,000, with an organic diisocyanate, wherein the weighted average value of the number average molecular weights of A and B is 4,500 to 8,000. The produced polyurethane resin has a molecular weight of 5,000 or 100,000.
OBJECTS OF THE INVENTION:
The principal objective of the present invention is to provide a single component, hybrid polyurethane binder resin suitable for formulating printing inks for high boil and retort applications.
Another objective of the present invention is to provide aromatic hydrocarbon free, in particular, toluene and ketone free (NTNK) printing ink which exhibits high boil & retort resistance, excellent printability and better lamination strength while lamination has been carried out with either solvent base or solvent-free lamination adhesives with various secondary substrate layers including polyethylene, polypropylene, metallized BOPP, CPP etc. Also, this ink exhibits excellent extrusion lamination bond strength properties, if necessary.
SUMMARY OF THE INVENTION:
The present invention provides a one-component, hybrid polyurethane resin binder suitable for formulating printing inks for high boil and high retort applications. The hybrid polyurethane comprises: a diisocyanate, two high molecular weight (HMW) polyester polyol resins, and a polyether polyol resin. The number average molecular weight of the HMW polyester polyol resin A is 2000 to 12000 daltons, the number

average molecular weight of the HMW polyester polyol resin B is 2000 to 8000 daltons; and the number average molecular weight of the polyether polyol resin (C) is 500 to 2000 daltons.
DETAILED DESCRIPTION OF THE INVENTION:
The preferred embodiments of the present invention will be described in detail with the following disclosure and examples. The foregoing general description and the following detailed description are provided to illustrate only some embodiments of the present invention and not to limit the scope of the present invention. The invention is capable of other embodiments and can be carried out or practiced in various other ways.
Unless otherwise specified, all the technical and scientific terms used herein have the same meaning as is generally understood by a person skilled in the art pertaining to the present invention. All the patents published patent applications referred to throughout the entire disclosure herein, unless specified otherwise, are incorporated by reference in their entirety.
It is to be understood that the ranges provided herein include the stated range and any value or sub-range within the stated range. For example, a range from greater than 0 % by weight to about 25 % by weight should be interpreted to include not only the explicitly recited limits of greater than 0 % by weight to about 25 % by weight, but also to include individual values, such as 0.05 % by weight, 0.9 % by weight, 7 % by weight, 21 % by weight, etc., and sub-ranges, such as from about 1 % by weight to about 24 % by weight, from about 5 % by weight to about 20 % by weight, etc. Furthermore, when "about" is utilized to describe a value, this is meant to encompass minor variations (up to +/-10%) from the stated value.
Reference throughout this specification to "one embodiment," "an embodiment," "one example," or "an example" means that a particular feature, structure, or characteristic described in connection with the embodiment or example is included in at least one embodiment of the present disclosure. Thus, appearances of the phrases "in one embodiment," "in an embodiment," "one example," or "an example" in various places throughout this specification are not necessarily all referring to the same embodiment or example. Furthermore, the particular features, structures, or characteristics may be combined in any suitable combinations and/or sub-combinations in one or more

embodiments or examples. In addition, it should be appreciated that if any figures are provided herewith, they are for explanation purposes to persons ordinarily skilled in the art and that the drawings of them are not necessarily drawn to scale.
In this specification, certain aspects of one embodiment include process steps and/or operations and/or instructions described herein for illustrative purposes in a particular order and/or grouping. However, the particular order and/or grouping shown and discussed herein are illustrative only and not limiting. Those of skill in the art will recognise that other orders and/or grouping of the process steps and/or operations and/or instructions are possible and, in some embodiments, one or more of the process steps and/or operations and/or instructions discussed above can be combined and/or deleted. In addition, portions of one or more of the process steps and/or operations and/or instructions can be re-grouped as portions of one or more other of the process steps and/or operations and/or instructions discussed herein. Consequently, the particular order and/or grouping of the process steps and/or operations and/or instructions discussed herein do not limit the scope of the disclosure.
As used herein, the term "binder" means a polymeric resin that uniformly binds to the colourant. The binder may act as a medium to keep a colourant uniformly dispersed in a fluid ink carrier or act as a medium to adhesively apply the colourant to the substrate. Where the amount of binder is given as "% by weight" in a composition, it refers to the weight of the solid content of the binder used in the composition, which comprises of the actual binder only and excludes any solvents or other additives used in the synthesis of the binder.
As used herein, the term "substrate" means any surface or object to which an ink or coating can be applied. Substrates include, but are not limited to polymer film, plastics, plastic films, composites or combinations thereof. Substrates may mean to have one or more layers of metals, metal oxides, or any other inorganic substances.
As used herein, the term "article" or "articles" means a substrate or a combinations of the substrates such as layered substrates. Examples of articles include, but are not limited to polymer film, plastics, plastic films, composites or combinations thereof; and products such as packaging materials, containers, labels, a polyolefin (e.g. polyethylene or polypropylene), a polyester (e.g. polyethylene terephthalate), a metalized foil (e.g. laminated aluminium foil), metalized polyester, and the like.

According to an aspect of this invention a hybrid polyurethane (PU) resin is provided for high boil and high retort applications. The PU resin of the present invention is the reaction product of at least one diisocyanate and a mixture of high molecular weight (HMW) polyester polyol resins, and a polyether polyol resin, optionally in the presence of a catalyst, to form an isocyanate-terminated prepolymer, which prepolymer is extended with a chain extender such as amines to form the hybrid polyurethane resin of this invention. The hybrid polyurethane binder resins provide high boil and high retort ink compositions.
According to a different aspect of the present invention, provided is a method of preparing the hybrid PU compositions for laminating inks by reacting at least one diisocyanate with a mixture of polyester polyols and a polyether polyol, optionally in the presence of a catalyst, to form an isocyanate-terminated prepolymer; and then reacting said prepolymer with at least one chain extender in at least one solvent to form a binder resin, for high boil and high retort applications.
The hybrid polyurethane comprises: a diisocyanate, two high molecular weight (HMW) polyester polyol resins, and a polyether polyol resin.
The HMW polyester polyol resin (A) and HMW polyester polyol resin (B) of the present invention are the reaction products of dibasic acid and diols. The diols are selected from such as diethylene glycol (DEG), mono-ethylene glycol (MEG), methyl propane diol, methyl pentane diol (MPD), neo pentyl glycol (NPG), 1, 4-butane diol (1,4-BD), 1, 6-hexane diol (1,6-HD), 1,2 propane diol (1,2-PDO), etc. Preferably the diols are methyl pentane diol (MPD), and methyl propane diol or a combination thereof.
The dibasic acid used in the formulation of HMW polyester polyol resin (A) and HMW polyester polyol resin (B) of the present invention may include adipic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, maleic acid, fumaric acid, succinic acid, oxalic acid, malonic acid, pimelic acid, azelaic acid, suberic acid, glutaric acid, 1,4-cyclohexyl dicarbon acid, dimer acid, hydrogenated dimer acid, and the like. Of these, adipic acid is particularly preferred.
The number average molecular weight of a First HMW polyester polyol resin A is 2000 to 12000 daltons, more preferably 3000 to 6000 daltons.

The number average molecular weight of a second HMW polyester polyol resin B is 2000 to 8000 daltons, more preferably 2000 to 4000 daltons.
The number average molecular weight of a polyether polyol resin (C) is 500 to 2000 daltons, more preferably 500 to 1500 daltons.
According to a further aspect of the invention, an ink composition is provided for high boil and high retort applications comprising a hybrid polyurethane (PU) resin, and one or more organic solvents, colourants, and additives. The ink composition for high boil and high retort applications are useful in flexographic and/or gravure printing processes, particularly laminating packaging applications.
According to yet another aspect of the invention is a method of preparing an ink composition for high boil and high retort applications, by providing a hybrid polyurethane (PU) resin prepared by reacting at least one diisocyanate with a mixture of polyester polyols and a polyether polyol, optionally in the presence of a catalyst, to form an isocyanate-terminated prepolymer; and then reacting said prepolymer with at least one chain extender in at least one solvent to form a binder resin; and adding one or more organic solvents, colourants, and additives.
Method of preparation of polyester polyol resin A. and polyester polyol resin B
The calculated amount of diol was introduced into a 1 litter reaction kettle with condenser, stirrer, thermometer, and nitrogen gas inlet tube. Provision to take out condensation water as by-product through a column has also been provided in the reactor assembly. The required amount of adipic acid was then introduced and the mixture was allowed to react by heating up to 90-100°C. When the internal temperature was between 120 to 130°C, water was distilled out and the temperature of the column was gradually increased up to 90-95°C until the distilling out of water had slowed down. When the acid value of the reaction mixture was reduced to 25-30 mg KOH/g, then 0.01% of catalyst was added. The reaction was continued until the acid value dropped down to 2 mg KOH/g. Then vacuum was applied to keep the desired hydroxyl value as shown in Table 1 and Table 2 to get the desired polyester polyols, i.e. polyester polyol A and polyester polyol B.
Optionally, the HMW polyester polyol resin A and polyester polyol resin B can be partially reacted with diisocyanates in such a way that the hydroxyl values of the resulting hydroxyl terminated polyurethanes remain within the ranges of 20 to 60 mg

KOH / g. Examples of isocyanates suitable for this purpose of bringing the hydroxyl values of the resulting hydroxyl terminated polyurethanes remain within the ranges of 20 to 60 mg KOH / g include Isophorone diisocyanate (IPDI), Toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 2,2,4-trimethylhexamethylene diisocyanate (TMDI), Tetramethylxylene diisocyanate (TMXDI).
Formulation of polyester polyol resin A
The most preferred six embodiments of the invention to prepare the HMW polyester polyol resin A are given in examples 1, 2 and 3 depicted as Polyester polyol A1, Polyester polyol A2, and Polyester polyol A3 in Table 1.
Table 1
Formulation of polyester polyol resin B
The most preferred six embodiments of the invention to prepare the HMW polyester polyol resin B are given in examples 4, 5 and 6 depicted as Polyester polyol B1, Polyester polyol B2, and Polyester polyol B3 in Table 2.

Table 2
Method of preparation of Hybrid Polyurethane
The calculated amount of polyester polyol A and polyester polyol B and polyether polyol C was introduced in 1 litter reaction kettle with condenser, stirrer, thermometer, and nitrogen gas inlet tube at ambient temperature. The reaction mixture was stirred for 20 minutes; and the required amount of isocyanate was added to the reactor. The stirring was continued till the temperature of the reaction mixture is raised up to 80°C, and then 0.03-0.08% of catalysts were added and the exotherm (exotherm temperature should not exceed 90°C) was observed. After completion of the exotherm, the reactor temperature was kept up to 112°C for 1 to 1.5 hours until the desired isocyanate content has been achieved. The reaction mixture was cooled down to 50°C and the prepolymer was diluted using about 50% of N- Propyl acetate and Reverse Osmosis (RO) water. When, the temperature decreased below 45°C, the prepolymer was further diluted with about 18% of isopropanol (IPA). The required

quantity of chain extender amines were mixed with remaining isopropanol (IPA) added to the reactor.
Formulation of hybrid polyurethane:
The hybrid polyurethane of the present invention comprising polyol units (Polyol A, Polyol B and polyol C) and diisocyanate units is manufactured in such a way that the total polyol content is in the range of 15-35% by weight. The polyester polyols A1, A2, A3 and polyester polyols B1, B2, B3 are added in such a way that the weight ratio of polyester polyol A to polyester polyol B is in the range of 1.5 to 1.8. Similarly, the weight ratio of polyester polyols A and B to polyether polyol C is in the range of 4 to 4.5. The formulation has been adopted in such a way that the NCO/OH ratio of polyester polyol B to diisocyanate is in the range of 2.0 to 2.1, the NCO/OH ratio of total polyester polyol A to diisocyanate is in the range of 4.8 to 4.9 and the NCO/OH ratio of polyether polyol C to diisocyanate is in the range of 5.8 to 5.9. The total NCO/OH ratio of the total polyol to diisocyanate is in the range of 1.5 to 1.6. The tin-free catalysts are used within the range of 0.03 to 0.08%. A chain extender was added in such a way that the viscosity of the hybrid polyurethane does not increase beyond 10 poise at 25°C (using Brookfield viscometer). The solvent is aromatic or aliphatic or a combination thereof. The solvent is preferably aromatic hydrocarbon free.
Chain extenders such as amines and/or short-chain diols may be used in the hybrid polyurethane synthesis. Amine chain extenders are more preferable.
The amines used as chain extender may be Isophorone diamine (IPDA), aminoethyl ethanol amine, Ethylene diamine, Monoethanolamine, Diethylamine, Diethanol amine, Trimethyl hexamethylene diamine, diethylene triamine or a combination thereof. Preferably amines used are aminoethyl ethanol amine & trimethyl hexamethylene diamine. The weight percentage of amine used is 0 to 5%.
The short chain diols are selected from methyl propane diol, methyl pentane diol, neo pentyl glycol, hexane diol, 1,2 propane diol, mono-ethylene glycol, diethylene glycol, butane diol etc.

The diisocyanate used in the hybrid polyurethane formulation of the present invention may be selected from aromatic, cycloaliphatic and/ or aliphatic isocyanates.
Examples of suitable diisocyanates include, but are not limited to 1,4-
diisocyanatobutane, 1,6-diisocyanatohexane, 1,5-diisocyanato-2,2-dimethylpentane,
2,2,4- or 2,4,4-trimethyl-1,6-diisocyanatohexane, 1,10-diisocyanatodecane, 1,3- and
1,4-diiso-cyanatocyclo-hexane, 1 -isocyanato-5-isocyanatomethyl-3,3,5-
trimethylcyclohexane (isophorone diisocyanate) (IPDI), 2,3-, 2,4- and 2,6-diisocyanato-1-methylcyclohexane, 4,4'- and 2,4'-diisocyanatodicyclohexylmethane, 1-isocyanato-3(4)-isocyanatomethyl-1-methyl-cyclohexane, 2,4-, and 2,5- and 2,6-tolylene diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 4,4'- and 2,4'-diisocyanatodiphenylmethane, 1,3-bis(1 -isocyanato-1 -methylethyl)benzene, dimer diisocyanate and mixtures thereof. Preferably, a cycloaliphatic diisocyanate such as Isophorone diisocyanate (IPDI) is used.
The most preferred three embodiments of the invention to prepare the hybrid polyurethane comprising of the polyester polyol A and polyester polyol B aforementioned in Table 1 and Table 2 as Polyester Polyol A1, Polyester Polyol A2, and Polyester Polyol A3; and Polyester Polyol B1, Polyester Polyol B2, and Polyester Polyol B3 respectively. Also using a polyether polyol C.
Table 2

The polyether polyol is selected from polypropylene glycol from Dow Chemicals and Polytetrahydrofuran (PolyTHF) from BASF.
Ink Composition:
The present invention provides isocyanate free, aromatic hydrocarbon free hybrid polyurethane based ink composition, which is derived from a combination of two different polyester polyols (polyol A and polyol B) and a polyether polyol (Polyol C) reacted with a disocyanate in presence of amine chain extenders, aromatic hydrocarbon free solvent, at least one colourant, and at least one additive.
The hybrid polyurethane based binder is present in an amount of from about 5% to 25% by weight of the total ink composition, the solvent is present in an amount of from about 35% to 85% by weight of the total ink composition; and the colourant is present in an amount of from about 5% up to 30% by weight of the total ink composition, and additives are present in an amount of from about 2% to 15% by weight of the total ink composition, wherein the hybrid polyurethane based binder may be a single hybrid polyurethane, or a mixture of two or more different hybrid polyurethanes.

The solvents used in the formulation to dissolve the components of inks are aromatic-hydrocarbon-free solvents such as Ethyl acetate, Isopropyl acetate, n- Propyl acetate Ethanol, isopropanol, Methoxy propyl acetate.
However, a person skilled in the art pertaining to the present invention may optionally use certain quantity of aromatic hydrocarbon, ketonic or aliphatic solvents.
The additives in the ink composition of the present invention are the usual ink additives to adjust flow, surface tension, and gloss of printed ink. Such additives typically are polymeric dispersants, surface active agents, waxes, levelling agents, wetting agents, fillers, metal chelate type adhesion promoters, defrothers (anti-foam ing agent), an antistatic agent, a viscosity modifier or a combination thereof.
Examples of the colourants used in the printing ink composition of the present invention include the types of organic and inorganic pigments and dyes typically used in inks, paints, and recording agents and the like. The pigment may be any colour, including, as examples, a cyan pigment, a blue pigment, an indigo pigment, a green pigment, a yellow pigment, an orange pigment, a purple pigment, a violet pigment, a magenta pigment, a brown pigment, a white pigment, a black pigment, a pearlescent pigment, a metallic pigment (e.g. a silver pigment, a gold pigment, a bronze pigment), or combinations thereof.
Specific broad examples of organic pigments that may be used include azo-based, phthalocyanine-based, anthraquinone-based, perylene-based, perinone-based, quinacridone-based, thioindigo-based, dioxazine-based, isoindolinone-based, quinophthalone-based, azomethine azo-based, diketopyrrolopyrrole-based and isoindoline-based pigments. In the case of an indigo blue ink, it is preferable to use copper phthalocyanine, whereas in the case of the transparent yellow ink, from the viewpoints of cost and light resistance, the use of C.I. Pigment Yellow 83 is preferable.
Examples of suitable cyan, blue or indigo organic pigments include C.I. Pigment Blue 1, C.I. Pigment Blue 2, C.I. Pigment Blue 3, C.I. Pigment Blue 15, Pigment Blue 15:3, C.I. Pigment Blue 15:34, C.I. Pigment Blue 15:4, C.I. Pigment Blue 16, C.I. Pigment Blue 18, C.I. Pigment Blue 22, C.I. Pigment Blue 25, C.I. Pigment Blue 60, C.I. Pigment Blue 65, C.I. Pigment Blue 66, C.I. Vat Blue 4, and C.I. Vat Blue 60.

Some examples of green organic pigments include C.I. Pigment Green 1, C.I. Pigment Green 2, C.I. Pigment Green 4, C.I. Pigment Green 7, C.I. Pigment Green 8, C.I. Pigment Green 10, C.I. Pigment Green 36, and C.I. Pigment Green 45.
Some examples of orange organic pigments include C.I. Pigment Orange 1, C.I. Pigment Orange 2, C.I. Pigment Orange 5, C.I. Pigment Orange 7, C.I. Pigment Orange 13, C.I. Pigment Orange 15, C.I. Pigment Orange 16, C.I. Pigment Orange 17, C.I. Pigment Orange 19, C.I. Pigment Orange 24, C.I. Pigment Orange 34, C.I. Pigment Orange 36, C.I. Pigment Orange 38, C.I. Pigment Orange 40, C.I. Pigment Orange 43, and C.I. Pigment Orange 66.
Examples of suitable yellow organic pigments include C.I. Pigment Yellow 1, C.I. Pigment Yellow 2, C.I. Pigment Yellow 3, C.I. Pigment Yellow 4, C.I. Pigment Yellow 5, C.I. Pigment Yellow 6, C.I. Pigment Yellow 7, C.I. Pigment Yellow 10, C.I. Pigment Yellow 11, C.I. Pigment Yellow 12, C.I. Pigment Yellow 13, C.I. Pigment Yellow 14, C.I. Pigment Yellow 16, C.I. Pigment Yellow 17, C.I. Pigment Yellow 24, C.I. Pigment Yellow 34, C.I. Pigment Yellow 35, C.I. Pigment Yellow 37, C.I. Pigment Yellow 53, C.I. Pigment Yellow 55, C.I. Pigment Yellow 65, C.I. Pigment Yellow 73, C.I. Pigment Yellow 74, C.I. Pigment Yellow 75, C.I. Pigment Yellow 77, C.I. Pigment Yellow 81, C.I. Pigment Yellow 83, C.I. Pigment Yellow 93, C.I. Pigment Yellow 94, C.I. Pigment Yellow 95, C.I. Pigment Yellow 97, C.I. Pigment Yellow 98, C.I. Pigment Yellow 99, C.I. Pigment Yellow 108, C.I. Pigment Yellow 109, C.I. Pigment Yellow 110, C.I. Pigment Yellow 113, C.I. Pigment Yellow 114, C.I. Pigment Yellow 117, C.I. Pigment Yellow 120, C.I. Pigment Yellow 122, C.I. Pigment Yellow 124, C.I. Pigment Yellow 128, C.I. Pigment Yellow 129, C.I. Pigment Yellow 133, C.I. Pigment Yellow 138, C.I. Pigment Yellow 139, C.I. Pigment Yellow 147, C.I. Pigment Yellow 151, C.I. Pigment Yellow 153, C.I. Pigment Yellow 154, C.I. Pigment Yellow 167, C.I. Pigment Yellow 172, C.I. Pigment Yellow 180, and C.I. Pigment Yellow 185.
Examples of brown organic pigments include C.I. Pigment Brown 1, C.I. Pigment Brown 5, C.I. Pigment Brown 22, C.I. Pigment Brown 23, C.I. Pigment Brown 25, C.I. Pigment Brown 41, and C.I. Pigment Brown 42.

Examples of suitable magenta, red, or violet organic pigments include C.I. Pigment Red 1, C.I. Pigment Red 2, C.I. Pigment Red 3, C.I. Pigment Red 4, C.I. Pigment Red 5, C.I. Pigment Red 6, C.I. Pigment Red 7, C.I. Pigment Red 8, C.I. Pigment Red 9, C.I. Pigment Red 10, C.I. Pigment Red 11, C.I. Pigment Red 12, C.I. Pigment Red 14, C.I. Pigment Red 15, C.I. Pigment Red 16, C.I. Pigment Red 17, C.I. Pigment Red 18, C.I. Pigment Red 19, C.I. Pigment Red 21, C.I. Pigment Red 22, C.I. Pigment Red 23, C.I. Pigment Red 30, C.I. Pigment Red 31, C.I. Pigment Red 32, C.I. Pigment Red 37, C.I. Pigment Red 38, C.I. Pigment Red 40, C.I. Pigment Red 41, C.I. Pigment Red 42, C.I. Pigment Red 48(Ca), C.I. Pigment Red 48(Mn), C.I. Pigment Red 57(Ca), C.I. Pigment Red 57:1, C.I. Pigment Red 88, C.I. Pigment Red 112, C.I. Pigment Red 114, C.I. Pigment Red 122, C.I. Pigment Red 123, C.I. Pigment Red 144, C.I. Pigment Red 146, C.I. Pigment Red 149, C.I. Pigment Red 150, C.I. Pigment Red 166, C.I. Pigment Red 168, C.I. Pigment Red 170, C.I. Pigment Red 171, C.I. Pigment Red 175, C.I. Pigment Red 176, C.I. Pigment Red 177, C.I. Pigment Red 178, C.I. Pigment Red 179, C.I. Pigment Red 184, C.I. Pigment Red 185, C.I. Pigment Red 187, C.I. Pigment Red 202, C.I. Pigment Red 209, C.I. Pigment Red 219, C.I. Pigment Red 224, C.I. Pigment Red 245, C.I. Pigment Red 286, C.I. Pigment Violet 19, C.I. Pigment Violet 23, C.I. Pigment Violet 32, C.I. Pigment Violet 33, C.I. Pigment Violet 36, C.I. Pigment Violet 38, C.I. Pigment Violet 43, and C.I. Pigment Violet 50.
Carbon black may be a suitable inorganic black pigment. Examples of carbon black pigments include those manufactured by Mitsubishi Chemical Corporation, Japan (such as, e.g., carbon black No. 2300, No. 900, MCF88, No. 33, No. 40, No. 45, No. 52, MA7, MA8, MA100, and No. 2200B); various carbon black pigments of the RAVEN® series manufactured by Columbian Chemicals Company, Marietta, Ga., (such as, e.g., RAVEN® 5750, RAVEN® 5250, RAVEN® 5000, RAVEN® 3500, RAVEN® 1255, and RAVEN® 700); various carbon black pigments of the REGAL® series, the MOGUL® series, or the MONARCH® series manufactured by Cabot Corporation, Boston, Mass., (such as, e.g., REGAL® 400R, REGAL® 330R, and REGAL® 660R); and various black pigments manufactured by Evonik Degussa Corporation, Parsippany, N.J., (such as, e.g., Color Black FW1, Color Black FW2, Color Black FW2V, Color Black FW18, Color Black FW200, Color Black S150, Color Black S160, Color Black S170, PRINTEX® 35, PRINTEX® U, PRINTEX® V, PRINTEX® 140U, Special Black 5, Special Black 4A, and Special Black 4). An

example of an organic black pigment includes aniline black, such as C.I. Pigment Black 1.
Examples of white inorganic pigments that can be used in the printing ink composition of the present invention include titanium oxide, zinc oxide, zinc sulphide, barium sulphate, calcium carbonate, chromium oxide and silica. The use of titanium oxide as the white ink pigment is preferable in terms of the colouring power, covering power, chemical resistance and weather resistance.
Preparation of Ink Composition:
The most preferred six embodiments of the invention to prepare hybrid polyurethane based ink compositions for high boil and high retort applications using one of the aforementioned hybrid polyurethanes (i.e. Hybrid Polyurethane 1, Hybrid Polyurethane 2, and Hybrid Polyurethane 3 of Examples 7, 8, and 9 respectively) are given in examples 10, 11, and 12 in Table 3 depicted as lnk-1, lnk-2, and lnk-3; and hybrid polyurethane based ink compositions for high boil and high retort applications using a mixture of more than one hybrid polyurethanes are given in examples 13, 14, and 15 in Table 4 depicted as lnk-4, lnk-5, and lnk-6.
Table 3

Table 4
* Other aforementioned pigments or a mixture of pigments can be used to impart the desired colour to the ink composition.
In one embodiment, a printed substrate is provided by printing a polymeric substrate with the printing ink composition of the present invention.
In another embodiment, a printed laminate is provided by printing a polymeric substrate with the printing ink composition of the present invention, and a second substrate is laminated to the dried ink image on the first substrate.
Example 16.
A printed laminate is formed by applying a layer of the printing ink composition of the present invention onto a polyester (PET) film by gravure printing method and laminating the same with polyethylene (PE) film using solvent base or solvent-free adhesives.
Example 17.
A printed laminate is formed by applying a layer of the printing ink composition of the present invention onto a (PET) film by gravure printing method and laminating the same with polyolefin films such as polyethylene (PE) film, and polypropylene (PP) using film extrusion lamination.

Sample test result
The ink compositions were evaluated for their printing adhesion on suitable substrates, drying time, their resolubility in solvents, lamination bond strength, blocking resistance, boil resistance, retort resistance.
The tests were conducted for each of these above mentioned physical properties by the known test methods commonly followed in ink industries.
The ink composition evaluation results for Example 16 have been provided in the following Table 5, and the ink composition evaluation results for Example 17 have been provided in the following Table 6.
Table 5
Rating: 1=poor; 5=Excellent
Table 6

Blocking resistance 5 5 5 5 5 4
Rating: 1=poor; 5=Excellent
The ink compositions of the present invention exhibit excellent boil resistance, retort resistance, and excellent printing adhesion to substrate, drying, resolubility, lamination bond strength and blocking resistance properties. Also, the ink exhibits better extrusion lamination bond strength property.
Example 18.
A layered article is formed by laminating another film layer such as polyethylene, polypropylene, metallized BOPP, CPP etc. using solvent based lamination adhesives onto the printing ink composition printed side of the polyethylene terephthalate (PET) film of Example 16.
Example 19.
A layered article is formed by laminating another film layer such as polyethylene, polypropylene, metallized BOPP, CPP etc. extrusion lamination onto the printing ink composition printed side of the polyethylene terephthalate (PET) film of Example 17.
Although the present disclosure is described in terms of certain preferred embodiments and examples, other embodiments and examples will be apparent to those of ordinary skill in the art, given the benefit of this disclosure, including embodiments and examples that do not provide all of the benefits and features set forth herein, which are also within the scope of this disclosure. It is to be understood that other embodiments may be utilized, without departing from the true spirit and scope of the present invention being indicated by the following claims.

We claim:
1. A printing ink composition for high boil and high retort applications comprising:
a. about 5 to 25% by weight of at least one hybrid polyurethane binder resin,
wherein the at least one hybrid polyurethane binder resin is a reaction
product of at least one diisocyanate, a first high molecular weight (HMW)
polyester polyol (A), a second high molecular weight (HMW) polyester polyol
(B), and a polyether polyol (C),
a. wherein, the number average molecular weight of the first high molecular weight (HMW) polyester polyol (A) is about 2000 to 12000 daltons, more preferably about 3000 to 6000 daltons, the number average molecular weight of the second high molecular weight (HMW) polyester polyol (B) is about 2000 to 8000 daltons, more preferably about 2000 to 4000 daltons, and the number average molecular weight of the polyether polyol (C) is about 500 to 2000 daltons, more preferably about 500 to 1500 daltons,
b. about 35 to 85% by weight of a solvent selected from aromatic-hydrocarbon-
free solvents such as Ethyl acetate, Isopropyl acetate, n-Propyl acetate,
Ethanol, isopropanol, Methoxy propyl acetate,
c. about 5 to 30% by weight of a colourant; and
d. about 2 to 15% by weight of at least one additive selected from polymeric
dispersants, surface active agents, waxes, levelling agents, wetting agents,
fillers, metal chelate type adhesion promoters, defrothers (anti-foaming
agents), antistatic agents, a viscosity modifier, and combinations thereof.
2. The printing ink composition for high boil and high retort applications according to claim 1, wherein, the hybrid polyurethane has a total polyol content of about 15 to 35% by weight of the total polyurethane composition.
3. The printing ink composition for high boil and high retort applications according to claim 1, wherein, in the hybrid polyurethane, the weight ratio of the HMW polyester polyol (A) to the HMW polyester polyol (B) is about 1.5 to 1.8.

The printing ink composition for high boil and high retort applications according to claim 1, wherein, in the hybrid polyurethane, the weight ratio of the total HMW polyester polyols content (A + B) to the polyether polyol (C) content is about 4.0 to 4.5.
A method of preparation of a hybrid polyurethane binder resin to be used in a printing ink composition for high boil and high retort applications comprising the steps of:
a. reacting at least one diisocyanate, a first high molecular weight (HMW)
polyester polyol (A), a second high molecular weight (HMW) polyester polyol
(B), and a polyether polyol (C), optionally in the presence of a catalyst, to
form an isocyanate-terminated prepolymer,
a. wherein, the number average molecular weight of the first high molecular weight (HMW) polyester polyol (A) is about 2000 to 12000 daltons, more preferably about 3000 to 6000 daltons, the number average molecular weight of the second high molecular weight (HMW) polyester polyol (B) is about 2000 to 8000 daltons, more preferably about 2000 to 4000 daltons, and the number average molecular weight of the polyether polyol (C) is about 500 to 2000 daltons, more preferably about 500 to 1500 daltons; and
b. reacting said prepolymer with at least one chain extender in at least one
solvent to form the polyurethane binder resin.
The method of preparation of the hybrid polyurethane binder resin to be used in a printing ink composition for high boil and high retort applications according to claim 5, wherein, the hybrid polyurethane has a total polyol content of about 15 to 35% by weight of the total polyurethane composition.
The method of preparation of the hybrid polyurethane binder resin to be used in a printing ink composition for high boil and high retort applications according to claim 5, wherein, the HMW polyester polyol (A), the HMW polyester polyol (B), and the polyether polyol (C) are calculatedly added so that in the hybrid polyurethane, the weight ratio of the HMW polyester polyol (A) to the HMW polyester polyol (B) is about 1.5 to 1.8, and the weight ratio of the total HMW

polyester polyols (A+B) content to the polyether polyol (C) content is about 4.0 to 4.5.
8. The method of preparation of the hybrid polyurethane binder resin to be used in a printing ink composition for high boil and high retort applications according to claim 5, wherein, the reaction is controlled in a suitable manner, so that the NCO/OH ratio of polyester polyol (B) to diisocyanate is about 2.0 to 2.1, the NCO/OH ratio of total polyester polyol (A) to diisocyanate is about 4.8-4.9, and the NCO/OH ratio of polyether polyol (C) to diisocyanate is in between 5.8-5.9. The total NCO/OH ratio of the total polyol to isocyanate is in the range of 1.5-1.6.
9. A method of preparation of a printing ink composition for high boil and high retort applications comprising blending:
a. about 5 to 25% by weight of at least one hybrid polyurethane binder resin,
wherein the at least one hybrid polyurethane binder resin is a reaction
product of at least one diisocyanate, a first high molecular weight (HMW)
polyester polyol (A), a second high molecular weight (HMW) polyester polyol
(B), and a polyether polyol (C),
b. wherein, the number average molecular weight of the first high molecular weight (HMW) polyester polyol (A) is about 2000 to 12000 daltons, more preferably about 3000 to 6000 daltons, the number average molecular weight of the second high molecular weight (HMW) polyester polyol (B) is about 2000 to 8000 daltons, more preferably about 2000 to 4000 daltons, and the number average molecular weight of the polyether polyol (C) is about 500 to 2000 daltons, more preferably about 500 to 1500 daltons,
b. about 35 to 85% by weight of a solvent selected from aromatic-hydrocarbon-
free solvents such as Ethyl acetate, Isopropyl acetate, n-Propyl acetate,
Ethanol, isopropanol, Methoxy propyl acetate,
c. about 5 to 30% by weight of a colourant; and
d. about 2 to 15% by weight of at least one additive selected from polymeric
dispersants, surface active agents, waxes, levelling agents, wetting agents,
fillers, metal chelate type adhesion promoters, defrothers (anti-foaming
agents), antistatic agents, a viscosity modifier, and combinations thereof.

10. A printed substrate comprising: at least one coat of the printing ink composition
for high boil and high retort applications according to any one of the claims 1 to 4
on a substrate,
wherein, the substrate to be printed is a plastic film selected from polyethylene terephthalate, BOPP, etc, and a secondary film laminated with the printed substrate using solvent base or solvent less lamination adhesive is selected from polymeric films such as polyethylene, polypropylene, metallised BOPP, CPP.
11. An article comprising the printed substrate according to claim 10.