FIELD OF THE INVENTION:
The present invention relates to a method for printing a water-base ink and subsequently applying a top-coat on a paper-foil substrate or a metallised paper substrate.
BACKGROUND OF THE INVENTION:
Metallisation of polymeric films, paper, foils, or other film-like materials in high vacuum metallisation chamber is known. These film-like materials generally serve as the base for printing, which in turn are used as labels or for flexible packaging. Usually, an overcoat is applied to the metallised substrate.
WO2000077300A1 discloses a grease resistant packaging material comprising a paper substrate, a base coat layer over the paper substrate, a metal layer overlying the base coat layer, and a top-coating layer overlying the metal layer, wherein the coat layers are formed of a grease resistant polymeric coating formulation.
US3677792A discloses a method of metallising an article for decorative purposes involving the conventional steps of applying to the article a base coat, a vacuum metallised film over the base coat and a first top-coat over the vacuum metallised film and over the first top-coat, applying a second top-coat of a film-forming, liquid organic material having greater durability than the first top-coat and adapted to adhere and be compatible to the first top-coat.
EP2585635B1 discloses a process for preparing a metallised sheet-like woven or non-woven material substrate comprising fibrous material such as tissue, paper, cardboard, or nonwoven fabric, and a fluorescent agent containing top-coat over the metallisation.
WO1982003202A1 discloses a metallised plastic film-coated paper laminate for use as a decorative and packaging wrap and for reflective insulation. The metallised laminate comprises a paper sheet base layer, a thermoplastic polymer film extruded onto a surface of the paper layer, and a thin metallic layer deposited onto the free surface of the plastic film so that the plastic film is sandwiched between the metallic layer and the paper sheet.

NL2008251C2 discloses a heat-sealable multi-layer wrapping material for packaging food, that includes a non-woven base material layer, a metal layer, a gas and / or vapour-barrier-forming coating layer, and a heat seal layer that is located on the inner surface of the covering material.
IN-MUM-2008-00785A discloses a tamper resistant security sealing tape that includes a metallised polyester film, wherein the printing of indicia and/ or logo is done on flexographic printing machine using commercially available flexographic printing inks that may be water-based, solvent based and/ or UV curable ink.
Conventionally metallised substrates are coated with solvent based inks. However, solvent-based inks typically comprise high volatile organic content (VOC) due to the presence of the solvents generally in the range of 50% to 70% or more. However, it is known that the ink was dried by evaporation of the solvent, which tends to result in undesirable environmental and health effects and fire hazards.
In order to avoid the environmental problems due to the high VOC of solvent-based inks water-based inks were tried. However, in case of water-based inks, in order to evaporate the water from the ink in order to dry the ink after printing, the printed metallised substrate is heated at a temperature of about 80 aC or above; hence the printed substrates such as paper substrates tend to shrink creating a problem in the registration. When the substrate shrinks, the graphic design on the substrate gets distorted.
The inventors of the present invention have identified a method of printing a water-base ink and subsequently applying a top-coat on a paper-foil substrate or a metallised paper substrate that eliminates the above mentioned problems.
OBJECTS OF THE INVENTION:
The principal objective of the present invention is to provide a method of printing a water-base ink and subsequently applying a top-coat on a paper-foil substrate or a metallised paper substrate without allowing the substrate to shrink.
Another objective of the present invention is to provide a method of printing a water-

base ink and subsequently applying a top-coat on a paper-foil substrate or a metallised paper substrate without creating any registration problem.
A further objective of the present invention is to provide a method of printing a water-base ink and subsequently applying a top-coat on a paper-foil substrate or a metallised paper substrate without distorting the graphic design over the paper-foil substrate or the metallised paper substrate.
Yet another objective of the present invention is to provide a method of printing a water-base ink and subsequently applying a top-coat on a paper- foil substrate or a metallised paper substrate without adversely affecting the oxidation of the printing substrate.
A further objective of the present invention is to provide a method of printing a water-base ink and subsequently applying a top-coat on a paper-foil substrate or a metallised paper substrate that helps the water-base ink gets properly dried in order to achieve optimum printing speed.
Another objective of the present invention is to provide a method of printing a water-base ink and subsequently applying a top-coat on a paper-foil substrate or a metallised paper substrate to achieve desired adhesion between the paper-foil substrate or the metallised paper substrate and the printed ink.
SUMMARY OF THE INVENTION:
A method of forming a layered article having a top-coated paper-foil substrate, comprising the steps of providing a paper film having a first surface and a second surface, providing a foil on the first surface of the paper film, applying a primer layer to the surface of the foil that is away from the paper film, printing a water-base ink above the primer layer; and applying a top-coat on top of the water-base ink.
In another embodiment a method of forming a layered article having a top-coated metallised paper substrate, comprising the steps of providing a paper film having a first surface and a second surface, depositing a metal layer on the first surface of the paper film, printing a water-base ink to the surface of the metal layer that is away from the paper film, and applying a top-coat on top of the water-base ink.

The process parameters include allowing a continuous airflow at a temperature of 50 aC to 100 aC at an adjusted hood height, wherein, the temperature of the chill roller is controlled at a temperature of 18 aC to 25 aC.
BRIEF DESCRIPTION OF THE DRAWINGS:
Fig. 1 illustrates a top-coated paper-foil substrate article prepared according to the teachings of the present invention.
Fig. 2 illustrates a top-coated metallised paper substrate article prepared according to the teachings of the present invention.
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.
Hood means an arrangement with vented chambers that blow hot or cold air.
"Chill roller", or "chilling roller" or "chiller roller" as may interchangeably be used in this specification means an internally-cooled metal roller or cylinder used to lower the temperature of the printed web at various stations in a printing process.
"Printing speed" or "speed of printing" as may interchangeably be used in this specification expressed in units of m/m (metres/minute) means the speed at which a substrate is printed and escapes any of the several rollers used in the printing process.

Foil as used in this specification means a very thin sheet of metal, such as aluminium foil.
As shown in Figure 1, a layered article (1) having a top-coated paper-foil substrate, comprising the steps of providing a paper film (101) having a first surface (101a) and a second surface (101b), providing a foil (102) on the first surface (101a) of the paper film, applying a primer layer (103) to the surface of the foil (102) that is away from the paper film, printing a water-base ink (104) above the primer layer; and applying a top¬coat (105) on top of the water-base ink.
In another embodiment as shown in Figure 2, forming a layered article (2) having a top-coated metallised paper substrate, comprising the steps of providing a paper film (201) having a first surface (201a) and a second surface (201b), depositing a metal layer (202) on the first surface (201a) of the paper film, printing a water-base ink (203) to the surface of the metal layer (202) that is away from the paper film, and applying a top-coat (204) on top of the water-base ink.
The above objectives of the invention are achieved by appropriate control of several vital parameters in the printing process as given in the following lines.
a. increasing the hood height to at least 5 feet or above with continuous airflow
between 50 aC to 100 aC preferably by IR heating,
b. by controlling the temperature of the chill roller between 18 aC to 25 aC,
c. by controlling the printing speed between 50 m/m (metres/minute) to 400 m/m ,
more preferably 100 m/m to 300 m/m, most preferably 150 m/m to 250 m/m,
The foil layer in Fig.1 is of a thickness of 5-20 u, and the metal layer in Fig. 2 is of a thickness of 5 - 40 nm.
The water-base ink layer has a thickness of 0.5 to 3.0 grams per square metre (gsm), and the top-coat layer has a thickness of 0.5 to 3.0 grams per square metre (gsm).
The water-base ink is Sarjo® Flex Plus ink (from Yansefu Inks and Coatings Pvt. Ltd.), and the top-coat is selected from a solvent-base type top-coat, ultraviolet (UV) type top-coat, electron beam (EB) type top-coat, light-emitting diode (LED) type top¬coat.

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.
Example 1 to 5
Process parameters for forming the layered article having a top-coated paper-foil substrate
The most preferred five embodiments of the invention are disclosed here showing the parameters for forming the layered article having a top-coated paper-foil substrate according to Figure 1 are given below in Table 1.
Table 1
Example 6 to 10
Process parameters for forming the layered article having a top-coated
metallised paper substrate
The most preferred five embodiments of the invention are disclosed here showing the parameters for forming the layered article having a top-coated metallised paper substrate according to Figure 2 are given below in Table 2.

Table 2
Property Evaluation results for Examples 1 to 5
The evaluation results for the layered article having a top-coated paper-foil substrate have been provided in Table 3.
Table 3
Rating: 1=poor; 5=Excellent
Property Evaluation results for Examples 6 to 10
The evaluation results for the layered article having a top-coated metallised paper substrate have been provided in Table 4.

Table 4
* Rating: 1=poor; 5=Excellent
Example 11
Layered article having a top-coated paper-foil substrate
As shown in Figure 1, a layered article having a top-coated paper-foil substrate that includes a paper film having a first surface and a second surface, a foil provided on the first surface of the paper film, a primer layer applied on the surface of the foil that is away from the paper film, a water-base ink printed above the primer layer; and a top-coat applied on top of the water-base ink, wherein the foil layer is of a thickness of 5-20 u, wherein the water-base ink layer has a thickness of 0.5 to 3.0 grams per square metre (gsm); and the top-coat layer has a thickness of 0.5 to 3.0 grams per square metre (gsm), wherein the water-base ink is Sarjo® Flex Plus ink (from Yansefu Inks and Coatings Pvt. Ltd.); and the top-coat is selected from a solvent-base type top-coat, ultraviolet (UV) type top-coat, electron beam (EB) type top-coat, light-emitting diode (LED) type top-coat.
Example 12
Layered article having a top-coated metallised paper substrate
As shown in Figure 2, a layered article having a top-coated metallised paper substrate that includes a paper film having a first surface and a second surface, a metal layer deposited on the first surface of the paper film, a water-base ink printed on the surface of the metal layer that is away from the paper film; and a top-coat applied on top of the water-base ink, wherein the metal layer is of a thickness of 5 -

40 nm, wherein the water-base ink layer has a thickness of 0.5 to 3.0 grams per square metre (gsm); and the top-coat layer has a thickness of 0.5 to 3.0 grams per square metre (gsm), wherein the water-base ink is Sarjo® Flex Plus ink (from Yansefu Inks and Coatings Pvt. Ltd.); and the top-coat is selected from a solvent-base type top-coat, ultraviolet (UV) type top-coat, electron beam (EB) type top-coat, light-emitting diode (LED) type top-coat.
The method of printing a water-base ink and subsequently applying a top-coat on a paper-foil substrate or a metallised paper substrate of the present invention has the following advantages:
• does not allow the substrate to shrink,
• helps in adequate registration,
• does not distort the graphic design over the paper-foil substrate or the metallised paper substrate,
• does not adversely affect the oxidation of the printing substrate,
• helps the water-base ink to get properly dried in order to achieve optimum printing speed,
• helps to achieve desired adhesion between the paper-foil substrate or the metallised paper substrate and the printed ink.
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 method of forming a layered article having a top-coated paper-foil substrate,
comprising the steps of:
a) providing a paper film having a first surface and a second surface,
b) providing a foil on the first surface of the paper film,
c) applying a primer layer to the surface of the foil that is away from the paper film,
d) printing a water-base ink above the primer layer; and
e) applying a top-coat on top of the water-base ink,
wherein, during the process of layered article formation, a continuous airflow is allowed from a hood to the layered article at a temperature of 50 aC to 100 aC at an adjusted hood height,
wherein, the temperature of the chill roller is controlled at a temperature of 18 aC to 25 aC.
2. A method of forming a layered article having a top-coated metallised paper
substrate, comprising the steps of:
a) providing a paper film having a first surface and a second surface,
b) depositing a metal layer on the first surface of the paper film,
c) printing a water-base ink to the surface of the metal layer that is away from the paper film; and
d) applying a top-coat on top of the water-base ink,
wherein, during the process of layered article formation, a continuous airflow is allowed from a hood to the layered article at a temperature of 50 aC to 100 aC at an adjusted hood height,
wherein, the temperature of the chill roller is controlled at a temperature of 18 aC to 25 aC.
3. The method of forming the layered article according to claim 1 or 2, wherein the top-coat is selected from a solvent-base type top-coat, ultraviolet (UV) type top-coat, electron beam (EB) type top-coat, light-emitting diode (LED) type top-coat.
4. The method of forming the layered article according to claim 1 or 2, wherein the hood height is elevated to at least a height of 5 feet.

5. The method of forming the layered article according to claim 1 or 2, wherein, the printing of the water-base ink is done at a printing speed of between 50 m/m (metre/minute) to 400 m/m (metre/minute), more preferably between 100 m/m (metre/minute) to 300 m/m (metre/minute), most preferably 150 m/m (metre/minute) to 250 m/m (metre/minute).
6. The method of forming the layered article according to claim 1, wherein the foil layer is of a thickness of 5-20 u.
7. The method of forming the layered article according to claim 2, wherein the metal layer is of a thickness of 5 - 40 nm; and the metal layer is deposited by a method such as vacuum deposition and transfer metallisation.
8. The method of forming the layered article according to claim 1 or 2, wherein the water-base ink is printed by rotogravure printing,
wherein the water-base ink layer has a thickness of 0.5 to 3.0 grams per square
metre (gsm); and
the top-coat layer has a thickness of 0.5 to 3.0 grams per square metre (gsm).
9. A layered article having a top-coated paper-foil substrate, comprising:
a) a paper film having a first surface and a second surface,
b) a foil provided on the first surface of the paper film,
c) a primer layer applied on the surface of the foil that is away from the paper film,
d) a water-base ink printed above the primer layer; and
e) a top-coat applied on top of the water-base ink,
wherein the foil layer is of a thickness of 5-20 u,
wherein the water-base ink layer has a thickness of 0.5 to 3.0 grams per
square metre (gsm); and
the top-coat layer has a thickness of 0.5 to 3.0 grams per square metre
(gsm),
the top-coat is selected from a solvent-base type top-coat, ultraviolet (UV)
type top-coat, electron beam (EB) type top-coat, light-emitting diode (LED)
type top-coat.
10. A layered article having a top-coated metallised paper substrate, comprising:
a) a paper film having a first surface and a second surface,
b) a metal layer deposited on the first surface of the paper film,

c) a water-base ink printed on the surface of the metal layer that is away from the paper film; and
d) a top-coat applied on top of the water-base ink,
wherein the metal layer is of a thickness of 5 - 40 nm,
wherein the water-base ink layer has a thickness of 0.5 to 3.0 grams per
square metre (gsm); and
the top-coat layer has a thickness of 0.5 to 3.0 grams per square metre
(gsm),
the top-coat is selected from a solvent-base type top-coat, ultraviolet (UV)
type top-coat, electron beam (EB) type top-coat, light-emitting diode (LED)
type top-coat.