FIELD OF THE INVENTION:
The present invention relates to a chlorine-free, aromatic hydrocarbon free hybrid polyurethane based ink composition for improved polypropylene (PP)/ Polyethylene (PE) extrusion lamination.
BACKGROUND OF THE INVENTION:
Chlorine base binders such as chlorinated polypropylene (CPP) and chlorinated ethylene vinyl acetate copolymer (CEVA) are not good as components in ink compositions that are used in packaging printing, especially the inks used in printing of food packages, due to their toxicity and poor recyclability of chlorine-containing resin binders. Again, the chlorine base binders are usually 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, as well as the disposal of the these solvents. Also these solvents 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.
JPH04213375 discloses a gravure ink composition for heat lamination containing an ethylene vinyl acetate copolymer, a chlorinated polypropylene and a vinyl chloride isobutyl vinyl ether copolymer. The chlorinated composition is used for printing on treated polyolefin film without using adhesive.
US3676391 discloses coating compositions that comprise a mixture of chlorinated polyolefin and ethylene/vinyl acetate copolymer or acrylic copolymers.
JPS57209974 discloses a printing ink composition that contains a binder obtained by blending a chlorinated, partially hydrolysed ethylene/vinyl acetate copolymer with a chlorinated polypropylene.
JP2005232217 discloses an ink composition that contains a chlorinated polypropylene graft- modified with maleic acid, a polyether urethane resin and an ethylene vinyl acetate copolymer; the chlorinated compositions provide adhesion to a polypropylene film.
JP2006057056 discloses a chlorinated gravure ink for polypropylene films, containing a binder resin that includes a chlorinated polypropylene and chlorinated ethylene

vinyl acetate copolymer and toluene is not used as the ink solvent.
US20130202860A1 discloses an ink composition, which uses a chlorine-free copolymer binder resin, whereas the ink composition uses aromatic hydrocarbon solvents such as xylene and toluene.
OBJECTS OF THE INVENTION:
The principal objective of the present invention is to provide a chlorine-free, aromatic hydrocarbon free environmentally safe ink composition.
Another objective of the present invention is to provide an ink composition that allows improved polypropylene (PP)/ Polyethylene (PE) extrusion lamination.
A further objective of the present invention is to provide a printed article using the provided ink compositions that exhibit improved adhesion characteristics to Polypropylene films and oriented polypropylene (OPP) films.
SUMMARY OF THE INVENTION:
The present invention relates to a chlorine-free, aromatic hydrocarbon free hybrid polyurethane based ink composition for improved polypropylene (PP)/ Polyethylene (PE) extrusion lamination.
The present invention provides chlorine-free, aromatic hydrocarbon free hybrid polyurethane based ink composition, which is derived from a combination of two different polyols (polyol A and polyol B) reacted with a diisocyanate in presence of amine chain extenders, at least one chlorine-free, 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 25% to 50% by weight of the total ink composition, the solvent is present in an amount of from about 15% to 50% by weight of the total ink composition; and the colourant is present in an amount of from about 6% up to 50% by weight of the total ink composition, and additives are present in an amount of from about 3% to 5% 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, n-propyl acetate, methoxy propyl acetate, Isopropyl acetate, Isopropanol, Ethanol.
However, a person skilled in the art pertaining to the present invention may optionally use certain quantity of aromatic hydrocarbon, ketonic or aliphatic solvents.
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.
Definitions of terms used in this specification:
The term "polyurethane", "PU", "urethane polymer", as used herein refers to a thermoplastic polymer which can be made crosslinkable (or thermosettable) and which is produced by the reaction of a polyisocyanate (i.e., an organic compound containing at least two isocyanate (-N=C=0) groups per molecule) and a polyol. The polymeric reaction product contains repeating urethane linkages (or carbamate ester linkages) of the structure:
H O I II -N-C—O—
When such linkages are present in a polymer, it is classified as polyurethane herein. Polyisocyanates also react with amines (that is, compounds which contain at least one primary or secondary amino
-NH2 or -NH

group per molecule (where Ri is typically an alkyl, aryl, or like hydrocarbonaceous radical) in a similar fashion to produce a polymeric reaction product that contains urea linkages:
H O H
I II I
-W-C—N —
Polymers containing both urethane and urea linkages are known as polyurethane ureas and such polyurethane polymers can be used as starting polymers in the practice of this invention.
Either the starting polyisocyanate or the starting polyol can itself have an internal polymeric structure. Examples of suitable structures include polyethers, polyesters, polyalkyls, polydimethylsiloxanes, and the like. Commonly used isocyanates in polyurethane synthesis include Isophorone diisocyanate (IPDI), toluene dissocyanate (TDI) and methylene bis (p-phenyl isocyanate) or 4,4'-dimethylmethane diisocyanate (MDI) although many other isocyanates are available. Commonly used polyols include polyester and polyethers. A polyurethane polymer can contain various functional (i.e., reactive) groups, such as one or more groups selected from the class consisting of isocyanato, hydroxyl and amino (particularly primary or secondary amino). Such functional groups are characteristically associated with polyurethane polymers. However, in addition to, or apart from, such functional groups, a polyurethane polymer can also contain other functional groups such as carboxyl groups, sulfonic acid groups, and the like, as those skilled in the art will appreciate.
A chemical compound with two or more hydroxyl (-OH) groups is known as a "polyol" in this disclosure. A polyol with exactly two -OH groups is a "diol". Similarly a polyol with just three -OH groups is a "triol".
Ink Composition
The present invention provides chlorine-free, aromatic hydrocarbon free hybrid polyurethane based ink composition, which is derived from a combination of two different polyols (polyol A and polyol B) reacted with a diisocyanate in presence of amine chain extenders, at least one chlorine-free, aromatic hydrocarbon free solvent, at least one colourant, and at least one additive.
Hybrid Polyurethane
The Polyol A used to prepare the polyurethane composition of the present invention is selected from polyether polyols such as polypropylene glycol and

Polytetrahydrofuran (PolyTHF) having molecular weight 2000 Daltons procured from Dow Chemicals and BASF respectively.
The polyurethane of the present invention comprising polyol units (Polyol A and polyol B) and diisocyanate units is manufactured in such a way that the total polyol content is in the range of 15-30%. Out of this polyol content, polyol A and Polyol B are each in the range of 5-15% of the total polyurethane composition. The formulation has been adopted in such a way that the NCO/OH ratio is in between 1.8 to 2.0. A tin-free catalyst is used within the range of 0.01 to 0.03%. Amines are added in such a way that the viscosity of the polyurethane does not increase beyond 5 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 B 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 diol is methyl pentane diol (MPD).
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 Isophorone diamine (IPDA), 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 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.

Method of preparation of Polyol B
The Polyol B is prepared from the diol and the dibasic by the following method.
The calculated amount of diol was introduced into a 1 litter reaction kettle with condenser, stirrer, thermometer, and Heating plate. Provision to take out condensation water as by-product 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. When the internal temperature was between 140 to 180 degree Centigrade, water was distilled out and the temperature was gradually increased to 200-230 degree centigrade until the distilled out water had slowed down. When the acid value of the reaction mixture was slowed down to 10-15, then 0.01% of catalyst (n-Butyl Titanate) 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.
Method of preparation of Polyurethane
The calculated amount of polyol A and polyol B was introduced in 1 litter reaction kettle with condenser, stirrer, thermometer, and nitrogen gas inlet tube at ambient temperature. Stir the reaction mixture for 20 minutes, the required amount of isocyanate has been added to the reactor. Continue the stirring till the temperature of the raised up to 60°C, add 0.01-0.03% of catalyst and observe exotherm (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. Cool down the reaction mixture to 50°C and the prepolymer has diluted using about 17% N- Propyl acetate. When, the temperature has decreased below 40°C, the prepolymer has been further diluted with 20% IPA and RO water. The required quantity of amines was mixed with remaining 30% of isopropanol and 4% N- Propyl acetate added to the reactor.
Formulation of the ink
The ink composition of the present invention comprises the aforementioned polyurethane ink binder in, a colourant (colouring agent) such as a pigment, organic solvents, and additives.
The polyurethane contained in the ink composition in the range of 25-50% by weight, more preferably 35- 45% by weight and most preferably about 40% by weight.

Solvents
The non-limiting organic solvents are selected from aliphatic alcohols, organic acid esters, glycol ethers, aliphatic ketones, aliphatic hydrocarbons or cycloaliphatic hydrocarbons.
Suitable aliphatic alcohols include but are not limited to ethanol, Isopropanol, normal-propanol, isobutanol and 1-Methoxy,2-Propanol or mixtures thereof.
Suitable organic acid esters include but are not limited to methyl acetate, ethyl acetate, propyl acetate, butyl acetate and mixtures thereof.
Suitable glycol ethers include but are not limited to diethylene glycol mono-n-butyl ether (DEGMBE), propylene glycol n-butyl ether, propylene glycol methyl ether, propylene glycol ethyl ether, dipropylene glycol methyl ether, dipropylene glycol n-butyl ether, propylene glycol methyl ether acetate, dipropylene glycol methyl ether acetate, propylene glycol n-propyl ether acetate, dipropylene glycol n-propyl ether, ethylene glycol n-butyl ether (or ethylene glycol monobutyl ether (EGMBE)), diethylene glycol n-butyl ether, triethylene glycol butyl ether, diethylene glycol methyl ether, tripropylene glycol monomethyl ether (TPGME), tripropylene glycol n-butyl ether (TPGBE), and triethylene glycol methyl ether.
Suitable aliphatic ketones include but are not limited to methyl ethyl ketone, methyl isobutyl ketone.
Suitable aliphatic hydrocarbons include but are not limited to pentane, hexane, heptane, octane, nonane, decane, isopentane, isohexanes, isopentanes, isooctanes, 2,2-dimethylbutane, and mixtures thereof.
Suitable cycloaliphatic hydrocarbons include but are not limited to cyclopentane, cyclohexane, methylcyclopentane, methylcyclohexane and mixtures thereof.
Mixtures of any of the above solvents may also be used.
In the ink compositions of the present invention, the total amount of solvent is between about from 15% to 50% by weight of the total ink composition (wt%).

Preferably solvents are aromatic hydrocarbon free solvents. However, a person skilled in the art pertaining to the present invention may also use certain quantity of aromatic, ketonic solvents or a combination thereof. If used, suitable aromatic hydrocarbons include but are not limited to toluene.
Colourants
The ink composition of the present invention may include a colourant.
The solid content of the colourant in the ink composition of the present invention is present in the range of about 6% to 50% by weight of the total weight of the ink composition (wt %).
The colourant may be organic based or inorganic based for example, azo compounds (monoazo, di-azo, p-Naphthol, Naphthol AS salt type azo pigment lakes, benzimidazolone, di-azo condensation, isoindolinone, isoindoline), and polycyclic (phthalocyanine, quinacridone, perylene, perinone, diketopyrrolo pyrrole, thioindigo, anthraquinone, indanthrone, anthrapyrimidine, flavanthrone, pyranthrone, anthanthrone, dioxazine, triarylcarbonium, quinophthalone) pigments, and mixtures of any of the foregoing. In certain embodiments, the organic material is selected from perylenes, quinacridones, phthalocyanines, isoindolines, dioxazines (that is, triphenedioxazines), 1,4-diketopyrrolopyrroles, anthrapyrimidines, anthanthrones, flavanthrones, indanthrones, perinones, pyranthrones, thioindigos, 4,4'-diamino-1,1'-dianthraquinonyl, as well as substituted derivatives thereof, and mixtures thereof.
The most common non-limiting pigments include azo dyes (for example, Solvent Yellow 14, Dispersed Yellow 23, and Metanil Yellow), anthraquinone dyes (for example, Solvent Red 111, Dispersed Violet 1 , Solvent Blue 56, and Solvent Orange 3), xanthene dyes (Solvent Green 4, Acid Red 52, Basic Red 1 , and Solvent Orange 63), azine dyes (for example, Jet Black), and the like.
Major usable non-limiting organic pigments include diarylide yellow AAOT (for example, Pigment Yellow 14 Cl#21095), diarylide yellow AAOA (for example, Pigment Yellow 12 Cl#21090), Phthalocyanine Blue (for example, Pigment Blue 15), lithol red (for example, Pigment Red 52:1 Cl#15860:1 ), toluidine red (for example, Pigment Red 22 Cl#12315), dioxazine violet (for example, Pigment Violet 23 Cl#51319), phthalocyanine green (for example, Pigment Green 7 Cl#74260), phthalocyanine blue (for example, Pigment Blue 15 Cl#74160), naphthoic acid red (for example, Pigment Red 48:2 Cl# 15865:2).

Examples of Inorganic pigments include titanium dioxide (for example, Pigment White 6 Cl#77891), carbon black (for example, Pigment Black 7 Cl#77266), iron oxides (for example, red, yellow, and brown), ferric oxide black (for example, Pigment Black 1 1 Cl#77499), chromium oxide (for example, green), ferric ammonium ferrocyanide (for example, blue), and the like.
Thus, the colourant may be any conventional organic or inorganic pigments without any restriction for example Zinc Sulfide, Pigment White 6, Pigment Yellow 1 , Pigment Yellow 3, Pigment Yellow 12, Pigment Yellow 13, Pigment Yellow 14, Pigment Yellow 17, Pigment Yellow 63, Pigment Yellow 65, Pigment Yellow 73, Pigment Yellow 74, Pigment Yellow 75, Pigment Yellow 83, Pigment Yellow 97, Pigment Yellow 98, Pigment Yellow 106, Pigment Yellow 1 14, Pigment Yellow 121 , Pigment Yellow 126, Pigment Yellow 127, Pigment Yellow 136, Pigment Yellow 174, Pigment Yellow 176, Pigment Yellow 188, Pigment Orange 5, Pigment Orange 13, Pigment Orange 16, Pigment Orange 34, Pigment Red 2, Pigment Red 9, Pigment Red 14, Pigment Red 17, Pigment Red 22, Pigment Red 23, Pigment Red 37, Pigment Red 38, Pigment Red 41 , Pigment Red 42, Pigment Red 57, Pigment Red 1 12, Pigment Red 122, Pigment Red 170, Pigment Red 210, Pigment Red 238, Pigment Blue 15, Pigment Blue 15:1 , Pigment Blue 15:2, Pigment Blue 15:3, Pigment Blue 15:4, Pigment Green 7, Pigment Green 36, Pigment Violet 19, Pigment Violet 23, Pigment Black 7 and the like.
Additives:
The ink composition of the present invention may also contain the usual ink additives to adjust flow, surface tension, and gloss of printed ink. Such additives typically are polymeric dispersants, surface active agents, waxes, or a combination thereof. The additives are present in an amount of from about 3% to 5% by weight of the total ink composition
These additives may function as levelling agents, wetting agents, fillers, dispersants, metal chelate type adhesion promoters, defrothers (anti-foaming agent), an antistatic agent, a viscosity modifier or other additives may be added to provide a specific function.
The ink composition may contain a polymeric dispersant when the colourant is a pigment to disperse the pigment during mixing and grinding operations in the solvent. All components of the ink may be blended together and ground to reduce the

pigment particles to the desired size distribution, typically 10 microns or less, or alternatively the pigment and the polymeric dispersant can be premixed and ground in the solvent to form a "base" which is subsequently blended with the remaining components of the gravure ink. The ink components may be mixed in a high speed mixer until a slurry consistency is reached and then passed through a media mill until the pigment is reduced to 10 microns or smaller. The wide versatility of the inks of this invention allows them to be prepared without a polymeric dispersant, but preferably they are made with a polymeric dispersant for grinding in, for example, polyvinyl butyral or blending with, for instance, a nitrocellulose base. Other useful colourants, and additives are also possible known to the persons skilled in the art.
Examples:
The present disclosure will now be explained in further detail by the following examples. These examples are illustrative of certain embodiments of the invention without being limited to the specific examples given here.
Synthesis Examples [Preparation of Polyol B]
The most preferred three embodiments of the invention to prepare the polyol B comprising of a dibasic acid and diol are depicted below as Polyol B (a), Polyol B (b), and Polyol B (c), given in examples 1 to 3 in table 1.
Table 1

[Preparation of Hybrid Polyurethane]
The most preferred three embodiments of the invention to prepare the polyurethane comprising of a polyol A and polyol B are depicted below in table 2 as Polyurethane 1, Polyurethane 2, and Polyurethane 3 using the Polyol B (a), Polyol B (b), Polyol B (c) from examples 1 to 3 of table 1.
Table 2
Preparation of the Ink composition
The most preferred six embodiments of the invention to prepare the hybrid polyurethane based ink composition using aforementioned polyurethanes are given in examples 7 to 9 in table 3 depicted as lnk-1 to lnk-3; and a mixture of more than one polyurethane are given in examples 10 to 12 in table 4 depicted as lnk-4 to Ink-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.
Sample test result
The ink composition evaluation results have been provided in the following Table 5.
Table 5

Rating: 1=poor; 5=Excellent
The ink composition of the present invention exhibit excellent printing adhesion to substrate, drying, resolubility, blocking resistance, extrusion performance.
Example 13. Printed article
A printed article, where an untreated substrate having a first surface and a second surface; and on one of first or second surface, a layer comprising a chlorine-free, aromatic hydrocarbon free ink composition of the present invention is coated, wherein the chlorine-free, aromatic hydrocarbon free ink composition layer has a thickness of from 0.25 to 20 microns thick when dried, wherein, the untreated substrate is a flexible plastic film,
wherein, a polyolefin film is extrusion laminated on top of the ink composition layer. The polyolefin film that is extrusion laminated is selected from a polypropylene film, a polyethylene film, a polypropylene copolymer film, a polyethylene copolymer film or an oriented polypropylene (OPP) film.
While various aspects and embodiments have been disclosed herein, other aspects, embodiments and uses of the invention will be apparent to those skilled in the art. It is intended that the specification and examples be considered as exemplary only, with the true scope and spirit of the invention being indicated by the following claims.

We claim:
1. A chlorine-free, aromatic hydrocarbon free ink composition comprising:
a hybrid polyurethane based binder derived from combination of two different
polyols (polyol A and polyol B) reacted with a diisocyanate in presence of amine
chain extenders,
at least one chlorine-free, aromatic hydrocarbon free solvent,
at least one colourant; and
at least one additive.
2. The chlorine-free, aromatic hydrocarbon free ink composition according to claim
1, wherein,
the polyol A in the hybrid polyurethane based binder is selected from polyether polyols such as polypropylene glycol (PPG) and Polytetrahydrofuran (PolyTHF) having molecular weight 2000 Daltons,
Polyol B 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), more preferably, methyl pentane diol (MPD), methyl pentane diol, neo pentyl glycol (NPG), most preferably methyl pentane diol (MPD),
the diisocyanate is selected from aromatic, cycloaliphatic and/ or aliphatic isocyanates, preferably, a cycloaliphatic isocyanate such as Isophorone diisocyanate (IPDI).
3. The chlorine-free, aromatic hydrocarbon free ink composition according to claim 1, wherein the chlorine-free, aromatic hydrocarbon free solvent is selected from aliphatic hydrocarbons, cycloaliphatic hydrocarbons, substituted aliphatic or cycloaliphatic hydrocarbons, aliphatic alkyl acetates, aliphatic alcohols, and combinations thereof.
4. The chlorine-free, aromatic hydrocarbon free ink composition according to claim 1, wherein the chlorine-free, aromatic hydrocarbon free solvent is selected from ethyl acetate, n-propyl acetate, methoxy propyl acetate, Isopropyl acetate,

Isopropanol, cyclohexane, butyl acetate, butanol, ethanol, and combinations thereof.
5. The chlorine-free, aromatic hydrocarbon free ink composition according to claim 1, wherein the colourant is selected from an organic pigment, an inorganic pigment, a dye and combinations thereof.
6. The chlorine-free, aromatic hydrocarbon free ink composition according to claim 1 additionally includes at least one additive such as a levelling agent, a wetting agent, a filler, a dispersant, an adhesion promoter, an anti-foaming agent, an antistatic agent, a viscosity modifier.
7. The chlorine-free, aromatic hydrocarbon free ink composition according to claim 1, wherein, the hybrid polyurethane based binder is present in an amount of from about 25% to 50% by weight of the total ink composition, the solvent is present in an amount of from about 15% to 50% by weight of the total ink composition; and the colorant is present in an amount of from about 6% up to 50% by weight of the total ink composition, and additives are present in an amount of from about 3% to 5% 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.
8. The chlorine-free, aromatic hydrocarbon free ink composition according to claim 1, wherein the ink composition is formulated as a gravure printing ink, a flexographic printing ink.
9. A printed article, comprising: an untreated substrate having a first surface and a second surface; and on at least one of the first surface or the second surface, a layer comprising a chlorine-free, aromatic hydrocarbon free ink composition of claim 1 is coated,
wherein the chlorine-free, aromatic hydrocarbon free ink composition layer has a thickness of from 0.25 to 20 microns thick when dried, wherein, the untreated substrate is a flexible plastic film,

wherein, a polyolefin film is extrusion laminated on top of the ink composition layer.
10. The printed article according to claim 9, wherein the polyolefin film is selected from a polypropylene film, a polyethylene film, a polypropylene copolymer film, a polyethylene copolymer film or an oriented polypropylene (OPP) film.