FIELD OF THE INVENTION:
The present invention relates to a nitrocellulose (NC) free printing ink for packaging of edible products, and in particular for pharmaceutical products packaging applications.
BACKGROUND OF THE INVENTION:
Nitrocellulose (NC) based printing inks are used for aluminium and blister packaging, particularly for pharmaceutical & food contact applications. The major disadvantage of NC based printing inks is that these inks possesses higher tendency to form nitrosamines which are carcinogenic in nature. When, nitrocellulose based inks are exposed to elevated temperatures, the nitro groups may dissociate, and these groups may end up as nitrogen oxides (NOx), which can produce carcinogenic nitrosamines. And when these carcinogenic nitrosamines come in contact with food or pharmaceutical products, can be a threat to sound living. That is why, the presence of nitrosamines has also been restricted in the formulation of printing inks as per various food safety regulations including Indian standard IS 15495:2004.
US6548572B1 discloses non-aqueous ink formulations for use on flexible film or paper packages for food, which require aseptic packaging conditions. The printed and coated packaging materials, and methods of aseptic packaging, as well as the aseptic packages are also disclosed. The coating formulation comprises a phenolic-modified co-solvent-type polyamide resin varnish, a nitrocellulose compound varnish, a non-aqueous solvent mixture, and additives.
CN105419466A discloses a quick-dry environment-friendly dark red printing ink comprising deionized water, pigment permanent red F4R, light fast scarlet, 107 molybdate red, nitrocellulose, polyamide resin liquid, ethylene glycol monobutyl ether, octyl acetate, tricresyl phosphate, butyl acetate, sodium sulfate, polyethylene microcrystal wax, a dispersing agent, a binding material, a wetting agent and polymethyl silicone.
R0113149B1 discloses a flexographic ink composition for printing on plastics through flexographic printing with photopolymer printing. The ink compositions consisting of nitrocellulose resin, polyamide resin, plasticizer, pigments, and solvents.
OBJECTS OF THE INVENTION:
The principal objective of the present invention is to provide a Nitrocellulose (NC) free printing ink suitable for packaging of edible products, and in particular for

pharmaceutical products packaging applications.
A further objective of the present invention is to provide an aromatic hydrocarbon free, in particular, non-toluene and non-ketonic (NTNK) printing ink.
Yet another objective of the present invention is to provide a printing ink that exhibits excellent heat resistance property and other pre and post application properties when printed on aluminium foil.
SUMMARY OF THE INVENTION:
The present invention provides a Nitrocellulose (NC) free printing ink suitable for packaging of edible products, and in particular for pharmaceutical products packaging applications.
The Nitrocellulose (NC) free printing ink composition of the present invention consists of about 5% to 15% by weight of a resin, about 6% up to 30% by weight of a colourant, about 65% to 85% by weight of a aromatic hydrocarbon free solvent, in particular, non-toluene and non-ketonic (NTNK) solvent or a mixture of such solvents, and about 3% to 7% by weight of additives.
The resin used in the formulation may be selected from Polyvinyl Butyral (PVB) resin, Cellulose Acetate Propionate (CAP) resin, Cellulose Acetate Butyrate (CAB) resin and combinations thereof. Most preferably the resin is Cellulose Acetate Propionate (CAP) resin.
The solvents used in the formulation to dissolve the components of inks are aromatic-hydrocarbon-free solvents such as Ethanol, Propanol, Butanol, Methoxy propanol, n-Propyl Acetate, Methyl propyl acetate, and mixtures thereof.
However, a person skilled in the art pertaining to the present invention may optionally use certain quantity of aromatic hydrocarbon or ketonic solvents.
Printed articles using the provided ink compositions exhibit excellent heat resistance property and other pre and post application properties when printed on aluminium foil.

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.
The present invention provides a Nitrocellulose (NC) free printing ink suitable for packaging of edible products, and in particular for pharmaceutical products packaging applications.
Formulation of the ink
The Nitrocellulose (NC) free printing ink composition of the present invention consists of about 5% to 15% by weight of a resin, about 6% up to 30% by weight of a colourant, about 65% to 85% by weight of a aromatic hydrocarbon free solvent, in particular, non-toluene and non-ketonic (NTNK) solvent or a mixture of such solvents, and about 3% to 7% by weight of additives.
The resin used in the formulation may be selected from Polyvinyl Butyral (PVB) resin, Cellulose Acetate Propionate (CAP) resin, Cellulose Acetate Butyrate (CAB) resin and combinations thereof. Most preferably the resin is Cellulose Acetate Propionate (CAP) resin.
The resin or a combination of resins is selected in such a way that the Tg is in the range of 140 °C to 150 °C and melting point is considerably in the range of 180 °C to 210 °C.
Cellulose acetate propionate is obtained by tri-esterifying cellulose with acetic acid and propionic acid, and then hydrolysing the product. Ordinarily, resins having a degree of acetylation of 0.6 to 2.5% by weight and a degree of propionation of 42 to 46% by weight, and having a hydroxyl group content of 1.8 to 5%, are commercially

available. According to an embodiment of the present invention, it is preferable to use a cellulose acetate propionate resin having a propionyl group content of 40 to 50% by weight (median value 45%), an acetyl group content of 0.5 to 3% by weight (median value 2.5%) and a hydroxyl group content of 2 to 6% by weight (median value 2.5%), and having a viscosity of 0.05 to 0.2 Pas.
Cellulose acetate butyrate is obtained by triesterifying cellulose with acetic acid and butyric acid, and then hydrolyzing the product. Ordinarily, resins having a degree of acetylation of 2 to 30% by weight and a degree of butyrylation of 17 to 53% by weight, and having a hydroxyl group content of 1 to 5%, are commercially available.
The solvents used in the formulation to dissolve the components of inks are aromatic-hydrocarbon-free solvents such as Ethanol, Propanol, Butanol, Methoxy propanol, n-Propyl Acetate, Methyl propyl acetate, and mixtures thereof.
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 includes 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 30% by weight of the total weight of the ink
composition.
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 7% 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.
An overprint varnish (OPV), having similar chemistry as ink formulation, can be optionally used with the printing ink, in order to improve the properties such as adhesion, gloss, heat resistance, when printed on the suitable substrate. The OPV if used, is essentially free from any nitro compounds or nitrocellulose (NC).
The components used in the ink formulation have been tested and verified to ensure that none of these components in the ink formulation contain any nitro compound.
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.

Preparation of the Ink composition
The most preferred six embodiments of the invention to prepare the ink composition of the present invention are given in examples 1 to 6 in table 1 depicted as lnk-1 to lnk-6.
Table 1
* Other aforementioned pigments or a mixture of pigments can be used to impart the desired colour to the ink composition of the present invention.
Example 7. Printed article
A printed article, where a treated substrate having a first surface and a second
surface; and on one of first or second surface, a layer comprising a Nitrocellulose
(NC) free printing ink composition of the present invention is coated,
wherein the Nitrocellulose (NC) free printing ink composition layer has a thickness of
about 0.1 to 3 GSM thick when dried,
wherein, the treated substrate is a foil.
The foil substrate that is printed is preferably an aluminium foil.

Sample test result
The performances of the Nitrocellulose (NC) free printing ink compositions printed on the foil substrate were evaluated. The evaluation results have been provided in the following table 2.
Table 2
Rating: 1=Poor; 5=Excellent
Advantages:
The ink compositions of the present invention exhibit excellent printing adhesion to substrate, drying, resolubility, printability properties on aluminium foil.
The printed articles using the Nitrocellulose (NC) free printing ink composition of the present invention exhibit excellent heat resistance and other pre and post application properties when printed on aluminium foil.
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.

CLAIMS
1. A nitrocellulose (NC) free printing ink for packaging applications comprising:
about 5% to 15% by weight of a resin,
about 6% up to 30% by weight of a colourant,
about 65% to 85% by weight of an aromatic hydrocarbon free, and ketone free
organic solvent; and
about 3% to 7% by weight of at least one additive.
2. The nitrocellulose (NC) free printing ink for packaging applications according to claim 1, wherein the resin is selected from Polyvinyl Butyral (PVB) resin, Cellulose Acetate Propionate (CAP) resin, Cellulose Acetate Butyrate (CAB) resin and combinations thereof, most preferably Cellulose Acetate Propionate (CAP) resin.
3. The nitrocellulose (NC) free printing ink for packaging applications according to claims 1 or 2, wherein the resin or combination of resins has a Glass Transition Temperature (Tg) of about 140 °C to 150 °C, and a melting point (MP) of about 180°Cto210°C.
4. The nitrocellulose (NC) free printing ink for packaging applications according to claim 1, wherein the components in the ink formulation are essentially free of any nitro compounds.
5. The nitrocellulose (NC) free printing ink for packaging applications according to claim 1, wherein the aromatic hydrocarbon free and ketone free organic solvent is selected from aliphatic hydrocarbons, cycloaliphatic hydrocarbons, substituted aliphatic or cycloaliphatic hydrocarbons, aliphatic alkyl acetates, aliphatic alcohols, and combinations thereof.
6. The nitrocellulose (NC) free printing ink for packaging applications according to claim 1, wherein the aromatic hydrocarbon free and ketone free organic solvent is selected from Ethanol, Propanol, Butanol, Methoxy propanol, n-Propyl Acetate, Methyl propyl acetate, and combinations thereof.
7. The nitrocellulose (NC) free printing ink for packaging applications according to claim 1, wherein the colourant is selected from an organic pigment, an inorganic pigment, a dye and combinations thereof.
8. The nitrocellulose (NC) free printing ink for packaging applications 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.
9. A printed article, comprising: a treated 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 nitrocellulose (NC) free printing ink composition of claim 1 is coated,
wherein the nitrocellulose (NC) free printing ink composition layer has a thickness of about 0.1 to 3 GSM thick when dried, wherein, the treated substrate is a foil.
10. The printed article according to claim 6, wherein the foil is an aluminium foil.