FIELD OF THE INVENTION:
The present invention relates to a high opacity white ink for lamination applications, specifically the present invention related to a high opacity white ink for lamination applications in combination with a mono-component or a two component primer which provides higher bond strength when laminated with solvent based adhesives.
BACKGROUND OF THE INVENTION:
Lately, with the development of printing technologies, the printing industry has developed rapidly, and printing has been utilized in all walks of life.
For packaging of goods such as foods, beverages, pharmaceuticals, cosmetics etc., it is required to use white inks to protect the packaged items from visible light exposure, provide good opacity to hide undesired visual effects, or to provide best possible whiteness from commercial viewpoint. White inks are used as back-up (background) to coloured inks in order to enhance both the colours and print quality. The higher the opacity of the background, higher is the colour and print enhancement.
The existing state of the art has some limitations with regard to the extent of opacity imparted to a printed package, especially via flexographic printing process, or gravure printing process. Especially, the existing commercial resins have poor opacity with white pigments.
Therefore, there remains a need to develop a PU resin that provides high opacity when formulated into inks using white pigments, and also maintains good adhesive bond strength properties without sacrificing their solubility in alcohol and ester mixtures.
Conventionally, the pigment concentration of white ink has been increased to achieve high opacity. Since, the amount of titanium dioxide present in white pigment increases, the concentration of resins or binders decreases in the ink formulation. Consequently, those white inks exhibit poor adhesion, blocking and bond strength properties especially on metallized PET substrates.
US9720341B2 discloses a high opacity white ink containing a mica-based mineral with titania.

CN110204959A discloses a white ink that includes titanium dioxide 30-40, acrylic resin 25-35%, opacity polymer 15-25%, dispersing agent 4-5%, deionized water 13-16%, and the composition having a total solid content of 28-32%.
WO2019126006A1 discloses a solvent-based high opacity ink that comprises one or more binders, Ti02 pigment, polymeric void hollow spherical particles, and one or more organic solvents, where the ink may also include mica-based pigments and aluminium pigments. The high opacity inks and coatings are designed for use on packaging where high opacity ink is needed, for example to hide undesired visual effects, or to protect the packaged goods.
US2011283908A1 discloses high opacity polyurethane resins and white inks made therefrom by formulating with white pigments. The Polyurethane resins based inks maintain good extrusion and adhesive lamination bonding strength properties and are used in flexographic and/or gravure printing processes as back-up for laminated packaging.
OBJECTS OF THE INVENTION:
The principal objective of the present invention is to provide a high opacity lamination white ink in combination with a mono-component or a two component primer which provides higher bond strength when laminated with solvent based adhesives.
Another objective of the present invention is to provide a high opacity lamination white ink that possesses good adhesion to polymeric substrates such as metallised polyethylene terephthalate (Met-PET) substrate, corona treated polyethylene terephthalate (CT PET).
A further objective of the present invention is to provide a high opacity lamination white ink that possesses quick drying qualities.
Another objective of the present invention is to provide a high opacity lamination white ink that possesses excellent re-solubility in preferably non-aromatic solvents such as alcohol, ester and alcohol/ester blends.
Yet another objective of the present invention is to provide a high opacity lamination white ink that possesses superior adhesive lamination bond strength to polymeric substrates such as metallised polyethylene terephthalate (Met-PET) substrate, corona treated polyethylene terephthalate (CT PET).

A further objective of the present invention is to provide a printed substrate printed with the high opacity lamination white ink of the present invention.
Another objective of the present invention is to provide an article comprising a printed substrate printed with the high opacity lamination white ink of the present invention.
SUMMARY OF THE INVENTION:
The present invention relates to a high opacity polyurethane resin based white ink, where the polyurethane resins are produced by polymerisation of diisocyanates with polyols and followed by chain extension with a chain extender such as amines. The polyurethane resins provide high opacity lamination white inks that maintain improved adhesive lamination bond strength to polymeric substrates such as metallised polyethylene terephthalate (Met-PET) substrate, corona treated polyethylene terephthalate (CT PET), good blocking resistance, quick drying, and good re-solubility characters in alcohol and ester solvents. The high opacity lamination white inks are useful in flexographic and/or gravure printing processes for laminated packaging.
A printed substrate is provided by printing a polymeric substrate with the high opacity lamination white ink, and an article preferably a packaging article is provided obtained comprising the printed substrate. Preferably the polymeric substrates to be printed are metallised polyethylene terephthalate (Met-PET), corona treated polyethylene terephthalate (CT PET).
In order to form a multi-layered laminate structure, a second substrate may be laminated to the dried ink image on the first substrate by any known method to form a printed laminate.
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 "opacity", as used in the printing industry or in arts, is defined as the extent to which a substrate is opaque to incident light, which is going away from transparency. Opacity in other words also defined as the state or ability of a substrate to absorb or block incident light, by either transmission through the substrate or by reflection from the surface of the substrate. Opacity is typically measured as a relative value on the scale from 0 to 100 opacity units, termed as "L" value, where an "L" value of 0 (zero) is for a fully transparent material, and an "L" value of 100 is a fully opaque material to light. While, an opacity value of about 55 to 56 is considered as "good opacity", an opacity value of more than 56 is considered "excellent opacity" or "high opacity".
As used herein, the term "binder" means a polymeric resin that uniformly binds to the pigment. The binder may act as a medium to keep a pigment uniformly dispersed in a fluid ink carrier or act as a medium to adhesively apply the pigment 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, a polyester (e.g. polyethylene terephthalate), metalized polyester, and the like.
According to an aspect of the present invention a high opacity polyurethane (PU) resin is provided that is the reaction product of at least one diisocyanate and at least one polyol, 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 polyurethane resin of this invention. The high opacity polyurethane binder resins provide high opacity laminating ink compositions that are useful in flexographic and/or gravure printing processes.
According to a different aspect of the present invention, provided is a method of preparing high opacity PU compositions for laminating inks by reacting at least one diisocyanate with at least one 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, wherein, the polyurethane binder resin forms high opacity laminating ink compositions that are used in flexographic and/or gravure printing processes.
The polyurethane of the present invention comprising polyol units and diisocyanate units is manufactured in such a way that the total polyol content is in the range of 15-35%. Diisocyanates are added in such a way that the total diisocyanate content is in the range of 2-10%. The formulation has been adopted in such a way that the NCO/OH ratio is in between 2 to 2.3. A tin-free catalyst is used within the range of 0.01 to 0.03%. Chain extenders such as amines are added in such a way that the viscosity of the polyurethane does not increase beyond 15 poise at 25°C (measured using Brookfield viscometer). The solvent is aromatic or aliphatic or a combination thereof. The solvent is preferably aromatic hydrocarbon free.
The preferred polyol is polyester polyol. The polyester polyols of the present invention are the reaction products of adipic acid and diols. The diols are selected from such as methyl pentane diol (MPD), methyl propane diol, neo pentyl glycol (NPG), hexane diol (HD), butane diol (BD), 1,2 propane diol (1,2-PDO), mono-ethylene glycol (MEG), diethylene glycol (DEG) etc. Preferably the diols are methyl pentane diol (MPD), neo pentyl glycol (NPG) and methyl propane diol. Most preferably the diols are methyl pentane diol (MPD) and neo pentyl glycol (NPG).
Chain extenders such as amines and/or short-chain diols may be used in the 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 the amines used in the present invention are aminoethyl ethanol

amine and trimethyl hexamethylene diamine. The weight percentage of amine used is 0 to 5%.
The diisocyanate used in the 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.
According to a further aspect of the invention, a high opacity lamination ink composition is provided for lamination applications comprising polyurethane resin, at least one pigment, and one or more organic solvents. The high opacity lamination inks are useful in flexographic and/or gravure printing processes, particularly laminating packaging applications. The pigment preferably is a white pigment, most preferably titanium dioxide.
According to yet another aspect of the invention is a method of preparing a high opacity lamination ink, by providing a high opacity polyurethane binder resin prepared by reacting at least one diisocyanate with at least one polyol, optionally in the presence of a catalyst, to form an isocyanate-terminated prepolymer, and reacting said prepolymer with at least one amine in at least one solvent to form a binder resin; adding at least one white pigment; optionally, adding one or more organic solvents.
According to a different aspect of the invention is a method of providing a high opacity back-up for laminated packaging comprising the step of flexographic printing or gravure printing using the above high opacity lamination ink, particularly a high opacity lamination white ink comprising a white pigment.

In order for the ink formulation to be used for flexographic and gravure printing applications, it is important for the resin to be soluble in organic solvents such as alcohol, ester and alcohol/ester blends. The high opacity polyurethane resin of the present invention is soluble in organic solvents, such as alcohols, esters and alcohol/ester blends, and is particularly useful in formulating high opacity lamination inks for packaging applications.
High opacity lamination ink compositions formed with the polyurethane resin of the invention exhibit excellent lamination bond strengths, blocking resistance, printability, resolubility, and superior adhesion on a wide variety of films especially to polymeric substrates.
While any polymeric substrate may be printed with this method, preferred polymeric substrates include corona treated polyethylene terephthalate (CT PET), metallized polyethylene terephthalate (Met-PET). More preferably the polymeric substrates to be printed are Met-PET films.
In order to form a multi-layered laminate structure, a second substrate may be laminated to the dried ink image on the first substrate by any known method to form a printed laminate. Accordingly, a preformed second substrate or a combination of preformed second substrates may be laminated to the dried ink image through an adhesive surface.The second substrate or a combination of second substrates may be different from the first substrate, or it may be the same material as the first substrate decided based on the end application of the printed laminate.
In one embodiment, the diol used in the formulation of polyester polyol resin of the present invention is Methyl propane diol from Perstorp, the dibasic acid is Adipic acid from RHODIA.
In another embodiment, the diol used in the formulation of polyester polyol resin of the present invention is Methyl pentane diol (MPD) from Kuraray Japan, the dibasic acid is Adipic acid from RHODIA.
In yet another embodiment, the diol used in the formulation of polyester polyol resin of the present invention is Neopentyl Glycol from Kuraray Japan, the dibasic acid is Adipic acid from RHODIA.

The number average molecular weight of the polyester polyol resins are 2000 to 12000 daltons, more preferably 3000 to 6000 daltons.
The method of preparation of the polyester polyol resin is given here. 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 column was gradually increased up to 90-95°C until the distilled out water had slowed down. When the acid value of the reaction mixture was slowed down 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. Then vacuum was applied to keep the desired hydroxyl value as shown in the table 1.
Optionally, the polyester polyol resin can be partially reacted with isocyanates. Examples of isocyanates suitable for use according to this invention include, Isophorone diisocyanate (IPDI), Toluene diisocyanate (TDI), 4,4'-diphenylmethane diisocyanate (MDI), 2,2,4-trimethylhexamethylene diisocyanate (TMDI), Tetramethylxylene diisocyanate (TMXDI) in such a way that the hydroxyl values of the hydroxyl terminated polyurethanes remain within the ranges of 20 to 60 mg KOH
/g-
Formulation of polyester polyol resin
The most preferred six embodiments of the invention to prepare the polyester polyol resin for formulating polyurethane for high opacity lamination white ink are given in examples 1, 2 and 3 in table 1.
Table 1

POLYURETHANE COMPOSITION
The polyurethane of the present invention comprising polyol units and diisocyanate units is manufactured in such a way that the total polyol content is in the range of 15-35% by weight. Isocyanates are added in such a way that the total isocyanate content is in the range of 2-10% by weight. The formulation has been adopted in such a way that the NCO/OH ratio is in between 2 to 2.3. A tin-free catalyst is used within the range of 0.01 to 0.03% by weight. Chain extender amines are added in such a way that the viscosity of the polyurethane does not increase beyond 15 poise at 25°C (using Brookfield viscometer). The solvent is aromatic or aliphatic or a combination thereof. The solvent is preferably aromatic hydrocarbon free. The preferred polyol is the reaction products of adipic acid and the diols such as methyl pentane diol (MPD), methyl propane diol, neo pentyl glycol (NPG), hexane diol (HD), butane diol (BD), 1,2 propane diol (1,2-PDO), mono-ethylene glycol (MEG), diethylene glycol (DEG) etc. The preferred diols are methyl pentane diol (MPD), neo pentyl glycol (NPG) and methyl propane diol.
The most preferable diols are methyl pentane diol (MPD), methyl pentane diol, neo pentyl glycol (NPG).
The isocyanate used in the polyurethane formulation of the present invention may be selected from aromatic, cycloaliphatic and/ or aliphatic isocyanates. Preferably, a cycloaliphatic isocyanate such as Isophorone diisocyanate (IPDI) is used.
Chain extenders such as amines and/or short-chain diols may be used in the

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 and trimethyl hexamethylene diamine. The weight percentage of amine used is 0 to 5% by weight of the total composition.
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.
Method of preparation of Polyurethane
The calculated amount of polyol 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, the required amount of isocyanate has been added to the reactor. The stirring was continued until the temperature was raised up to 60°C, 0.01-0.03% of catalyst was added and the exotherm was observed (Exotherm temperature should not exceed 70°C). After completion of exotherm, the reactor temperature was kept up to 80°C for 1-1.5 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 52% Ethyl acetate. When, the temperature has decreased below 40°C, the prepolymer has been further diluted with about 12% by weight of isopropanol. The required quantity of amines was mixed with remaining quantity of isopropanol and ethyl acetate and was added to the reactor.
Formulation of polyurethane
The most preferred three embodiments of the invention to prepare the polyurethane as depicted below in table 2 as Polyurethane 1, Polyurethane 2, and Polyurethane 3 using the Polyester Polyol-1, Polyester Polyol-2, and Polyester Polyol-3 from examples 1 to 3 of table 1.
Table 2

High opacity Ink composition:
The present invention provides an aromatic hydrocarbon free such as toluene free polyurethane based high opacity ink composition comprising polyurethane resin binder of the present invention, aromatic hydrocarbon free solvents, at least one pigment, preferably a white pigment and at least one additive.
The polyurethane based binder is present in an amount of from about 5% to 20% by weight of the total ink composition, the solvent is present in an amount of from about 40% to 75% by weight of the total ink composition; and the pigment, preferably a white pigment is present in an amount of from about 20% up to 40% by weight of the total ink composition, and additives are present in an amount of from about 3% to 12% by weight of the total ink composition, wherein the polyurethane based binder may be a single polyurethane, or a mixture of two or more different polyurethanes according to the present invention.
The solvents used in the formulation to dissolve the components of high opacity inks are aromatic-hydrocarbon-free solvents such as Ethyl acetate, Isopropyl acetate, n-Propyl acetate, Ethanol, isopropanol, Methoxy propyl acetate, Methyl ethyl ketone, methyl isobutyl ketone.
The additives in the high opacity 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-foaming agent), an antistatic agent, a viscosity modifier or a combination thereof.

In one embodiment of the present invention, a mono-component primer with this high opacity lamination white ink for lamination process is preferably used since it reduces the complications of using primer and hardener in correct mixing ratio for the personnel working in production during printing process, which sometimes leads to errors and consequently change the properties of the printing inks. Also, it is easily accessible to use during the printing process. Use of such primer provides higher bond strength when laminated with solvent based adhesives.
In another embodiment of the present invention, a two-component primer is used with this high opacity lamination white ink for lamination process.
The mono-component primer is selected from commercial grade Sarjo®film Plus Primer TF (SRJFILMPLE007); Sarjo®film Plus Primer (SRJFILMPLE006) from Yansefu® Inks and Coatings Private Limited, India.
The two-component primer is selected from commercial grade 2K primer (PMA036) with 2K Hardener (PMA037) Yansefu® Inks and Coatings Private Limited, India.
The solvent based adhesive is selected from commercial grade Sarjo®bond YL-580A; Sarjo®bond YL-611 A; Sarjo®bond YL-711 A; Sarjo®bond YL-680A Yansefu® Inks and Coatings Private Limited, India.
The white pigment used in the present invention is preferably titanium dioxide (Ti02)
Preparation of high opacity Ink composition:
The most preferred six embodiments of the invention to prepare the polyurethane based high opacity lamination white ink composition for lamination applications using aforementioned polyurethanes are given in examples 1 to 3 in table 1 above are depicted as lnk-1 to lnk-3 in table 3 below as examples 7 to 9; and a mixture of more than one polyurethane are given in examples 4 to 6 in table 2 are depicted as lnk-4 to lnk-6 in table 4 below as examples 10 to 12.
Table 3

Table 4
In one embodiment, a printed substrate is provided by printing a polymeric substrate with the high opacity lamination white ink, and an article preferably a packaging article is obtained comprising the printed substrate.
In another embodiment, a printed substrate is provided by printing a polymeric substrate with the high opacity lamination white ink, and a second substrate is laminated to the dried ink image on the first substrate to prepare an article.
Example 13.
A printed substrate is formed by applying a layer of the high opacity lamination white ink of the present invention onto the metallised side of a Met-PET film by gravure printing method.

Sample test result for physical properties
The printed substrate was evaluated for its opacity ("L" value), and other physical properties.
"L" value test result:
The "L" value or opacity value of high opacity lamination white ink printed Met-PET film of Example 13 has been evaluated using "AGS Exact X-rite Pantone" instrument. The L value evaluation results of high opacity lamination white ink composition have been provided in the following Table 5.
Table 5
Other physical properties test result:
The physical properties evaluation results for the high opacity lamination white ink coated Met-PET substrate have been provided in the following Table 6.
Table 6

Rating: 1=poor; 5=Excellent
The high opacity lamination white ink compositions of the present invention exhibit excellent printing adhesion to the Met-PET substrate, quick drying, resolubility, bond strength and blocking resistance properties.
Example 14.
A layered article is formed by laminating a preformed layer of a Polyethylene (PE) or corona treated polyethylene terephthalate (CT PET) film onto the high opacity lamination white ink printed side of the Met-PET film.
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 high opacity lamination white ink composition, comprising:
a. about 5% to 20% by weight of a polyurethane binder resin, wherein the
polyurethane binder resin is a reaction product of at least one diisocyanate,
and one or more polymeric polyols,
wherein, the number average molecular weight of the one or more polymeric polyols is 2000 to 12000 daltons, preferably 3000 to 6000 daltons,
b. about 40% to 75% 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, Methyl ethyl ketone,
methyl isobutyl ketone,
c. about 20% to 40% by weight of a white pigment; and
d. about 3% to 12% 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 high opacity lamination white ink composition according to claim 1, wherein the white pigment is titanium dioxide (Ti02).
3. The high opacity lamination white ink composition according to claim 1, wherein the polymeric polyol is a polyester polyol.
4. A method of preparation of a polyurethane binder resin to be used in a high opacity lamination white ink composition comprising the steps of:
a. reacting at least one diisocyanate with one or more polymeric polyols,
optionally in the presence of a catalyst, to form an isocyanate-terminated
prepolymer,
wherein, the number average molecular weight of the one or more polymeric polyols is 2000 to 12000 daltons, preferably 3000 to 6000 daltons; and
b. reacting said prepolymer with at least one chain extender in at least one
solvent to form the polyurethane binder resin.

5. The method of preparation of the polyurethane binder resin to be used in the high opacity lamination white ink composition according to claim 4, wherein the polymeric polyol is a polyester polyol.
6. A method of preparation of a high opacity lamination white ink composition, comprising blending:
a. about 5% to 20% by weight of a polyurethane binder resin, wherein, the
polyurethane binder resin is a reaction product of at least one diisocyanate,
and one or more polymeric polyols,
wherein the number average molecular weight of the one or more polymeric polyols is 2000 to 12000 daltons, preferably 3000 to 6000 daltons,
b. about 40% to 75% 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, Methyl ethyl ketone,
methyl isobutyl ketone,
c. about 20% to 40% by weight of titanium dioxide (Ti02) white pigment; and
d. about 3% to 12% 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
agent), antistatic agents, a viscosity modifier, and combinations thereof.
7. A printed substrate comprising: at least one coat of the high opacity lamination
white ink composition according to any one of the claims 1 to 3 on a substrate,
wherein, the high opacity lamination white ink composition provides the printed
substrate a measured "L" value of about 86 to 92.
8. The printed substrate according to claim 7, wherein, the substrate is a polymer containing film selected from polyethylene terephthalate (PET), metallized polyethylene terephthalate (Met-PET), corona treated polyethylene terephthalate (CT PET), preferably the substrate is a metallised polyethylene terephthalate (Met-PET) film.

9. The printed substrate according to claim 7, wherein, where the substrate to be printed is a metallised substrate, and the at least one coat of the high opacity lamination white ink composition is applied on the metallised side of the substrate.
10. An article comprising the printed substrate according to any of the claims 7 to 9.