DESC:FIELD
The present disclosure relates to a screen printing ink composition and a process for its preparation. Particularly, the present disclosure relates to water-based screen-printing ink compositions for printing on plastic substrates and plastic containers.
DEFINITIONS
As used in the present disclosure, the following terms are generally intended to have the meaning as set forth below, except to the extent that the context in which they are used indicates otherwise.
Screen Printing refers to a printing technique where a stencilled design is transferred onto a substrate by using a polyester mesh as a screen and ink.
Screen Printing Ink refers to an ink composition that is specifically developed for printing on a substrate by using the screen printing technique.
Screen stability refers to the ability of an ink composition to print for a long period of time without chocking on the screen.
Aliphatic refers to the terms alkyl, alkylene, alkenyl, alkenylene, alkynyl, and alkynylene.
The term “alkyl” refers to a straight or branched chain hydrocarbon having from one to twelve carbon atoms, optionally substituted with substituents selected from the group consisting of lower alkyl, lower alkoxy, lower alkylsulfanyl, lower alkylsulfenyl, lower alkylsulfonyl, oxo, hydroxy, mercapto, amino optionally substituted by alkyl, carboxy, carbamoyl optionally substituted by alkyl, aminosulfonyl optionally substituted by alkyl, nitro, cyano, halogen, or lower perfluoroalkyl, multiple degrees of substitution being allowed. Examples of “alkyl” as used herein include, but are not limited to, n-butyl, n-pentyl, isobutyl, and isopropyl, and the like.
The term “alkylene” refers to a straight or branched chain divalent hydrocarbon radical having from one to ten carbon atoms, optionally substituted with substituents selected from the group consisting of lower alkyl, lower alkoxy, lower alkylsulfanyl, lower alkylsulfenyl, lower alkylsulfonyl, oxo, hydroxy, mercapto, amino optionally substituted by alkyl, carboxy, carbamoyl optionally substituted by alkyl, aminosulfonyl optionally substituted by alkyl, nitro, cyano, halogen, or lower perfluoroalkyl, multiple degrees of substitution being allowed. Examples of “alkylene” as used herein include, but are not limited to, methylene, ethylene, and the like.
The term “alkenyl” refers to a hydrocarbon radical having from two to ten carbons and at least one carbon-carbon double bond, optionally substituted with substituents selected from the group consisting of lower alkyl, lower alkoxy, lower alkylsulfanyl, lower alkylsulfenyl, lower alkylsulfonyl, oxo, hydroxy, mercapto, amino optionally substituted by alkyl, carboxy, carbamoyl optionally substituted by alkyl, aminosulfonyl optionally substituted by alkyl, nitro, cyano, halogen, or lower perfluoroalkyl, multiple degrees of substitution being allowed.
The term “alkenylene” refers to a straight or branched chain divalent hydrocarbon radical having from two to ten carbon atoms and one or more carbon-carbon double bonds, optionally substituted with substituents selected from the group consisting of lower alkyl, lower alkoxy, lower alkylsulfanyl, lower alkylsulfenyl, lower alkylsulfonyl, oxo, hydroxy, mercapto, amino optionally substituted by alkyl, carboxy, carbamoyl optionally substituted by alkyl, aminosulfonyl optionally substituted by alkyl, nitro, cyano, halogen, or lower perfluoroalkyl, multiple degrees of substitution being allowed. Examples of “alkenylene” as used herein include, but are not limited to, ethene-1,2-diyl, propene-1,3-diyl, methylene-1,1-diyl, and the like.
The term “alkynyl” refers to a hydrocarbon radical having from two to ten carbons and at least one carbon-carbon triple bond, optionally substituted with substituents selected from the group consisting of lower alkyl, lower alkoxy, lower alkylsulfanyl, lower alkylsulfenyl, lower alkylsulfonyl, oxo, hydroxy, mercapto, amino optionally substituted by alkyl, carboxy, carbamoyl optionally substituted by alkyl, aminosulfonyl optionally substituted by alkyl, nitro, cyano, halogen, or lower perfluoroalkyl, multiple degrees of substitution being allowed.
The term “alkynylene” refers to a straight or branched chain divalent hydrocarbon radical having from two to ten carbon atoms and one or more carbon-carbon triple bonds, optionally substituted with substituents selected from the group consisting of lower alkyl, lower alkoxy, lower alkylsulfanyl, lower alkylsulfenyl, lower alkylsulfonyl, oxo, hydroxy, mercapto, amino optionally substituted by alkyl, carboxy, carbamoyl optionally substituted by alkyl, aminosulfonyl optionally substituted by alkyl, nitro, cyano, halogen, or lower perfluoroalkyl, multiple degrees of substitution being allowed. Examples of “alkynylene” as used herein include, but are not limited to, ethyne-1,2-diyl, propyne-1,3-diyl, and the like.
BACKGROUND
The background information hereinbelow relates to the present disclosure but is not necessarily prior art.
Printing inks are required for printing various substrates such as coated papers, uncoated papers, cardboard, plastic substrates, plastic containers, and the like, wherein the substrates are used in daily requirements. The key components of the ink composition are various colourants (pigment/dye) and vehicles. The printing inks are broadly categorized based on the type of vehicle used, such as water-based inks, oil-based inks, and solvent-based inks. The nature of the printing process and substrate determines the choice of printing inks.
Printing on plastic substrates is widely performed by using commercially available ink compositions based on mineral turpentine oil-based ink systems. Moreover, these ink systems require lead-containing driers to get the wet film dry through the oxidation drying process. The use of mineral turpentine oil as a solvent along with lead driers is toxic in nature, adversely impact human health, and also increases pollution in the environment. The other two ink systems are solvent-based inks and UV-curable inks. The solvent-based ink compositions contain volatile organic compounds (VOCs), which get evaporated into the atmosphere during the drying process after application on the substrate. The volatile organic compounds, after emission, mix with the air, thereby making the air polluted, which is hazardous to humans when inhaled. UV-curable inks are not preferred as they are very costly. Further, the use of UV-curable ink requires additional equipment, thereby increasing the cost, and hence are not commercially viable.
There is, therefore, felt a need to provide a screen printing ink composition that mitigates the drawbacks mentioned hereinabove or at least provides an alternative solution.
OBJECTS
Some of the objects of the present disclosure, which at least one embodiment herein satisfies, are as follows.
An object of the present disclosure is to ameliorate one or more problems of the background or to at least provide a useful alternative.
Another object of the present disclosure is to provide a screen printing ink composition.
Yet another object of the present disclosure is to provide a screen printing ink composition used for plastic containers.
Still another object of the present disclosure is to provide a screen printing ink composition that is water-based.
Another object of the present disclosure is to provide a screen printing ink composition which is devoid of volatile organic compounds (VOCs).
Yet another object of the present disclosure is to provide a screen printing ink composition that is an economical and environment-friendly green product.
Still another object of the present disclosure is to provide a process for the preparation of a screen printing ink composition.
Other objects and advantages of the present disclosure will be more apparent from the following description, which is not intended to limit the scope of the present disclosure.
SUMMARY
The present disclosure relates to a screen printing ink composition and a process for its preparation. In an aspect, the screen printing ink composition comprising a) a polymer in an amount in the range of 40 mass% to 60 mass% with respect to the total mass of the composition; b) a pigment in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the composition; c) a dispersing agent in an amount in the range of 2 mass% to 5 mass% with respect to the total mass of the composition; d) a softener in an amount in the range of 3 mass% to 8 mass% with respect to the total mass of the composition; e) a surface wetting agent in an amount in the range of 0.5 mass% to 3 mass% with respect to the total mass of the composition; f) a pH stabilizer in an amount in the range of 0.2 mass% to 0.5 mass% with respect to the total mass of the composition; g) an anti-foaming agent in an amount in the range of 0.1 mass% to 0.5 mass% with respect to the total mass of the composition; h) a cross-linking agent in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the composition; i) a filler in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the composition; j) a thickener in an amount in the range of 0.1 mass% to 2 mass% with respect to the total mass of the composition; k) a co-solvent in an amount in the range of 10 mass% to 20 mass% with respect to the total mass of the composition; l) optionally a surface modifier in an amount in the range of 0.5 mass% to 2 mass% with respect to the total mass of the composition; and m) q.s. deionized water.
In another aspect, the process for the preparation of the screen printing ink composition comprises blending a predetermined amount of a dispersing agent and deionized water for a first predetermined time period to obtain a first mixture. To the first mixture, predetermined amounts of a pH stabilizer and an anti-foaming agent are added and blended at a speed in the range of 500 rpm to 1000 rpm for a second predetermined time period to obtain a second mixture. To the second mixture, a predetermined amount of pigment is added and milled for a third predetermined time period to obtain a pigment dispersion with a particle size in the range of 0.1 µm to 2 µm. To the pigment dispersion, a predetermined amount of a polymer is added and blended at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a third mixture. The third mixture is blended with a predetermined amount of a co-solvent at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a fourth mixture. To the fourth mixture, a predetermined amount of a filler, a surface wetting agent, and a softener are added and blended at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a fifth mixture. The so obtained fifth mixture is blended with predetermined amounts of a thickener, a cross-linking agent, and optionally a surface modifier at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain the screen printing ink composition.
BRIEF DESCRIPTION OF THE DRAWING
The present disclosure will now be described with the help of the accompanying drawing, in which:
Figure 1 illustrates the layout of the images displaying the screen stability of the print by using screen printing ink composition (water-based) in accordance with the present disclosure, and conventional oil-based, and solvent-based ink composition; and
Figure 2 illustrates the basic hue composition produced in accordance with the present disclosure.

DETAILED DESCRIPTION
The present disclosure relates to a screen printing ink composition and a process for its preparation. Particularly, the present disclosure relates to water-based screen-printing ink compositions for printing on plastic substrates and plastic containers.
Embodiments, of the present disclosure, will now be described with reference to the accompanying drawing.
Embodiments are provided so as to thoroughly and fully convey the scope of the present disclosure to the person skilled in the art. Numerous details are set forth, relating to specific components and methods to provide a complete understanding of the embodiments of the present disclosure. It will be apparent to the person skilled in the art that the details provided in the embodiments should not be construed to limit the scope of the present disclosure. In some embodiments, well-known processes, well-known apparatus structures, and well-known techniques are not described in detail.
The terminology used in the present disclosure is only for the purpose of explaining a particular embodiment, and such terminology shall not be considered to limit the scope of the present disclosure. As used in the present disclosure, the forms "a,” "an," and "the" may be intended to include the plural forms as well unless the context clearly suggests otherwise. The terms "comprises," "comprising," “including,” and “having” are open-ended transitional phrases and therefore specify the presence of stated features, integers, steps, operations, elements, modules, units and/or components, but do not forbid the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. The particular order of steps disclosed in the method and process of the present disclosure is not to be construed as necessarily requiring their performance as described or illustrated. It is also to be understood that additional or alternative steps may be employed.
As used herein, the term "and/or" includes any and all combinations of one or more of the associated listed elements.
The terms first, second, third, etc., should not be construed to limit the scope of the present disclosure as the aforementioned terms may be only used to distinguish one element, component, region, layer or section from another component, region, layer or section. Terms such as first, second, third etc., when used herein do not imply a specific sequence or order unless clearly suggested by the present disclosure.
Printing inks are required for printing various substrates such as coated papers, uncoated papers, cardboard, plastic substrates and plastic containers, and the like, wherein the substrates are used in daily requirements. The key components of the ink composition are various colourants (pigment/dye) and vehicles. The printing inks are broadly categorized based on the type of vehicle used, such as water-based inks, oil-based inks, and solvent-based inks. The nature of the printing process and substrate determines the choice of printing inks.
Printing on plastic substrates is widely performed by using commercially available ink compositions based on mineral turpentine oil-based ink systems. Moreover, these ink systems require lead-containing driers to get the wet film dry through the oxidation drying process. The use of mineral turpentine oil as a solvent along with lead driers is toxic in nature, adversely impact human health, and also increases pollution to the environment. The other two ink systems are solvent-based inks and UV-curable inks. The solvent-based ink compositions contain volatile organic compounds (VOCs), which get evaporated into the atmosphere during the drying process after application on the substrate. The volatile organic compounds, after emission, mix with the air, thereby making the air polluted, which is hazardous to humans when inhaled. UV-curable inks are not preferred as they are very costly. Further, the use of UV-curable ink requires additional equipment, thereby increasing the cost, and hence are not commercially viable.
The present disclosure provides a screen printing ink composition and a process for preparing screen printing ink composition. The screen printing ink composition of the present disclosure has improved performance parameters and is volatile organic compounds, and also meets the eco-friendly and green product specifications.
a) a polymer in an amount in the range of 40 mass% to 60 mass% with respect to the total mass of the composition; b) a pigment in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the composition; c) a dispersing agent in an amount in the range of 2 mass% to 5 mass% with respect to the total mass of the composition; d) a softener in an amount in the range of 3 mass% to 8 mass% with respect to the total mass of the composition; e) a surface wetting agent in an amount in the range of 0.5 mass% to 3 mass% with respect to the total mass of the composition; f) a pH stabilizer in an amount in the range of 0.2 mass% to 0.5 mass% with respect to the total mass of the composition; g) an anti-foaming agent in an amount in the range of 0.1 mass% to 0.5 mass% with respect to the total mass of the composition; h) a cross-linking agent in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the composition; i) a filler in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the composition; j) a thickener in an amount in the range of 0.1 mass% to 2 mass% with respect to the total mass of the composition; k) a co-solvent in an amount in the range of 10 mass% to 20 mass% with respect to the total mass of the composition; l) optionally a surface modifier in an amount in the range of 0.5 mass% to 2 mass% with respect to the total mass of the composition; and m) q.s. deionized water.
In an embodiment of the present disclosure, the polymer is at least one selected from the group consisting of acrylic resin, PU (polyurethane) acrylic resin, acrylic copolymer resin, PU resin, and aliphatic PU resin. In an exemplary embodiment of the present disclosure, the polymer is acrylic resin.
In an embodiment of the present disclosure, the acrylic resin is at least one selected from the group consisting of butyl methyl acrylate, styrene acrylic emulsion, methyl acrylate, polymethyl methacrylate (PMMA), styrene acrylate, and butyl methyl acrylate. In an exemplary embodiment of the present disclosure, the acrylic resin is butyl methyl acrylate.
In an embodiment of the present disclosure, the acrylic resin is characterized by having
• solids in an amount in the range of 35% to 45%;
• a glass transition temperature (Tg) in the range of -10°C to 100°C; and
• an acid number in the range of 10 mg KOH/g to 90 mg KOH/g.
In an embodiment of the present disclosure, the aliphatic resin is at least one selected from the group consisting of aliphatic polyester polyurethane, aliphatic acrylic polyurethane, aliphatic polyether polyurethane, and aliphatic polyurethane dispersion.
In an embodiment of the present disclosure, the pigment is at least one selected from the group consisting of C.I. pigment yellow 12 (PY12), C.I. pigment yellow 13 (PY13), C.I. pigment yellow 14 (PY14), monoazo yellow (PY74), disazopyrazolone orange (PO13), benzidine pigment orange R (PO16), C.I. pigment orange 46 (PO46), C.I. pigment red 2 (PR2), C.I. pigment red 2 (PR3), C.I. pigment red 4 (PR4), C.I. pigment red 12 (12), C.I. pigment red 48, pigment red 48:1 (CB1855357), pigment red 48:2, pigment red 53, pigment red 57:2, pigment green 7 (PG7), pigment green 2 (PG2), phthal green 36 (PG36), pigment blue 15:2 (PB15:2), pigment blue 15:3 (PB15:3), pigment blue 15:6 (PB15:6), pigment blue 16, pigment blue 29, pigment blue 56, pigment blue 61, triarylcarbonium violet (PV3), pigment violet 37 (PV37), C.I. Pigment Black 6 (PB6), C.I. Pigment Black 7 (PB7), C.I. pigment white 6 (PW6), C.I. pigment white 7 (PW7), C.I. pigment white 18 (PW18), and C.I. pigment white 26 (PW26).
In an embodiment of the present disclosure, the dispersing agent is at least one selected from the group consisting of modified styrene-maleic acid copolymer solution, polyether solution, acrylic resin solution, mono propylene glycol, dipropylene glycol, tri-propylene glycol, mono-ethylene glycol, diethylene glycol, and polyol glycol. In an exemplary embodiment of the present disclosure, the dispersing agent is a combination of polyether solution and acrylic resin solution.
The dispersing agent helps to disperse pigments uniformly and avoid flocculation and formation of agglomerates of the pigment throughout the shelf life of the screen printing ink composition. The dispersing agents also provide a smooth flow to the ink while printing.
In an embodiment of the present disclosure, the softener is at least one selected from the group consisting of urea, hydroxyethyl ethylene urea, and alkylated urea. In an exemplary embodiment of the present disclosure, the softener is urea.
The softener acts as a humectant by reducing the clogging of the screen due to the drying of the ink.
In an embodiment of the present disclosure, the surface wetting agent is at least one selected from the group consisting of ethoxylated 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol, and ethoxylated acetylenic diols. In an exemplary embodiment of the present disclosure, the surface wetting agent is 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol.
In an embodiment of the present disclosure, the pH stabilizer is at least one selected from the group consisting of triethanolamine, ammonia, 2-amino-methyl-1-propanol, and NaOH. In an exemplary embodiment of the present disclosure, the pH stabilizer is triethanolamine.
In an embodiment of the present disclosure, the anti-foaming agent is at least one selected from the group consisting of acetylene glycol derivative, and ethoxylated C12-15 alcohols. In an exemplary embodiment of the present disclosure, the anti-foaming agent is ethoxylated C12-15 alcohol.
In an embodiment of the present disclosure, the cross-linking agent is at least one selected from the group consisting of aziridine, polyaziridine, aliphatic isocyanates, zinc ammonium carbonate solution, and trifunctional polyaziridine. In an exemplary embodiment of the present disclosure, the cross-linking agent is aziridine.
In an embodiment of the present disclosure, the filler is at least one selected from the group consisting of precipitated silica, silicon dioxide, silica matting agent, and pyrogenic silica. In an exemplary embodiment of the present disclosure, the filler is silicon dioxide.
In an embodiment of the present disclosure, the thickener is at least one selected from the group consisting of methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and hydroxypropyl methylcellulose (HPMC). In an exemplary embodiment of the present disclosure, the thickener is hydroxypropyl methyl cellulose.
In an embodiment of the present disclosure, the co-solvent is at least one selected from the group consisting of monoethylene glycol, propylene glycol, isopropyl alcohol, ethanol, and aqueous ethanol. In an exemplary embodiment of the present disclosure, the co-solvent is ethanol.
In an embodiment of the present disclosure, the surface modifier is at least one selected from the group consisting of polyethylene-based wax, paraffin base wax, polysiloxane, polyether modified siloxane, hydroxy-functionalized polydimethylsiloxane, and polyether modified siloxane.
In an embodiment of the present disclosure, the screen printing ink composition of the present disclosure comprises a sufficient quantity of deionized water.
In an embodiment of the present disclosure, the viscosity of the composition of the present disclosure is in the range of 5 poise to 35 poise.
In an embodiment of the present disclosure, the mass ratio of the polymer to the cross-linking agent is in the range of 1:0.025 to 1:0.07. In an exemplary embodiment of the present disclosure, the weight ratio of the polymer to the cross-linking agent is 1:0.04.
In an embodiment of the present disclosure, the mass ratio of the polymer to the dispersing agent is in the range of 1:0.05 to 1:0.09. In an exemplary embodiment of the present disclosure, the weight ratio of the polymer to the dispersing agent is in the range of 1:0.08.
In an embodiment of the present disclosure, the screen printing ink composition of the present disclosure is suitable for printing on substrates, wherein the substrate is selected from flame-treated polypropylene, corona-treated polypropylene (PP), polypropylene (white), polypropylene (clear), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polycarbonate, and acrylonitrile butadiene styrene (ABS).
In an embodiment of the present disclosure, the screen printing ink composition of the present disclosure is suitable to print on a substrate having a surface energy in the range of 38 dyne/cm to 48 dyne/cm.
In accordance with the embodiments of the present disclosure, the screen printing ink composition of the present disclosure can be used for screen printing by means of manual or automatic printing machines. The application of the ink composition can be customized based on the brightness and the opacity required for printing on the substrate.
In an embodiment of the present disclosure, the screen printing ink composition of the present disclosure provides enhanced ink storage stability, screen stability, print quality, improved adhesion, good levelling, scratch resistant, and water resistance, when printed on the substrate.
In an embodiment of the present disclosure, the screen printing ink composition of the present disclosure is devoid of volatile organic compounds.
In another aspect of the present disclosure, there is provided a process for the preparation of the screen printing ink composition.
The process is described in detail.
In a first step, a predetermined amount of a dispersing agent and deionized water are mixed for a first predetermined time period to obtain a first mixture.
In an embodiment of the present disclosure, the dispersing agent is at least one selected from the group consisting of modified styrene-maleic acid copolymer solution, polyether solution, acrylic resin solution, mono propylene glycol, dipropylene glycol, tri-propylene glycol, mono-ethylene glycol, diethylene glycol, and polyol glycol. In an exemplary embodiment of the present disclosure, the dispersing agent is polyether solution and acrylic resin solution.
In an embodiment of the present disclosure, the first predetermined time period is in the range of 10 minutes to 20 minutes. In an exemplary embodiment of the present disclosure, the first predetermined time period is 15 minutes.
In a second step, the predetermined amounts of a pH stabilizer and an anti-foaming agent are added to the first mixture and blended at a speed in the range of 500 rpm to 1000 rpm for a second predetermined time period to obtain a second mixture.
In an embodiment of the present disclosure, the second predetermined time period is in the range of 10 minutes to 20 minutes. In an exemplary embodiment of the present disclosure, the second predetermined time period is 15 minutes.
In an embodiment of the present disclosure, the pH stabilizer is at least one selected from the group consisting of triethanolamine, ammonia, 2-amino-methyl-1-propanol, and NaOH. In an exemplary embodiment of the present disclosure, the pH stabilizer is triethanolamine.
In an embodiment of the present disclosure, the anti-foaming agent is at least one selected from the group consisting of acetylene glycol derivative, ethoxylated C12-15 alcohols. In an exemplary embodiment of the present disclosure, the anti-foaming agent is ethoxylated C12-15 alcohol.
In a third step, a predetermined amount of pigment is added to the third mixture followed by milling for a third predetermined time period to obtain a pigment dispersion with a particle size in the range of 0.1 µm to 2 µm.
In an embodiment of the present disclosure, the third predetermined time period is in the range of 4 hours to 9 hours. In an exemplary embodiment of the present disclosure, the third predetermined time period is 6 hours.
In an embodiment of the present disclosure, the pigment is at least one selected from the group consisting of C.I. pigment yellow 12 (PY12), C.I. pigment yellow 13 (PY13), C.I. pigment yellow 14 (PY14), monoazo yellow (PY74), disazopyrazolone orange (PO13), benzidine pigment orange R (PO16), C.I. pigment orange 46 (PO46), C.I. pigment red 2 (PR2), C.I. pigment red 2 (PR3), C.I. pigment red 4 (PR4), C.I. pigment red 12 (12), C.I. pigment red 48, pigment red 48:1 (CB1855357), pigment red 48:2, pigment red 53, pigment red 57:2, pigment green 7 (PG7), pigment green 2 (PG2), phthal green 36 (PG36), pigment blue 15:2 (PB15:2), pigment blue 15:3 (PB15:3), pigment blue 15:6 (PB15:6), pigment blue 16, pigment blue 29, pigment blue 56, pigment blue 61, triarylcarbonium violet (PV3), pigment violet 37 (PV37), C.I. Pigment Black 6 (PB6), C.I. Pigment Black 7 (PB7), C.I. pigment white 6 (PW6), C.I. pigment white 7 (PW7), C.I. pigment white 18 (PW18), and C.I. pigment white 26 (PW26).
In a fourth step, a predetermined amount of a polymer is added to the pigment dispersion and blended at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a third mixture. In an exemplary embodiment of the present disclosure, the speed is 700 rpm and a time period is 15 minutes.
In an embodiment of the present disclosure, the polymer is at least one selected from the group consisting of acrylic resin, PU (polyurethane) acrylic resin, acrylic copolymer resin, PU resin, and aliphatic PU resin. In an exemplary embodiment of the present disclosure, the polymer is acrylic resin.
In an embodiment of the present disclosure, the acrylic resin is at least one selected from the group consisting of butyl methyl acrylate, styrene acrylic emulsion methyl acrylate, polymethyl methacrylate (PMMA), and styrene acrylate. In an exemplary embodiment of the present disclosure, the acrylic resin is butyl methyl acrylate.
In an embodiment of the present disclosure, the aliphatic resin is at least one selected from the group consisting of aliphatic polyester polyurethane, aliphatic acrylic polyurethane, aliphatic polyether polyurethane, and aliphatic polyurethane dispersion.
In a fifth step, a predetermined amount of a co-solvent is added to the fourth mixture and blended at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a fourth mixture.
In an embodiment of the present disclosure, the co-solvent is at least one selected from the group consisting of monoethylene glycol, propylene glycol, isopropyl alcohol, ethanol, and aqueous ethanol. In an exemplary embodiment of the present disclosure, the co-solvent is ethanol.
In a sixth step, a predetermined amount of a filler and a surface wetting agent, and a softener are added to the fourth mixture and blended at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a fifth mixture.
In an embodiment of the present disclosure, the filler is at least one selected from the group consisting of precipitated silica, silicon dioxide, silica matting agent, and pyrogenic silica. In an exemplary embodiment of the present disclosure, the filler is silicon dioxide.
The water-based ink compositions predominantly consist of water and have a high surface tension of 72.6 x 10-3N/m. The high surface tension of the water-based ink compositions leads to poor wetting of ink on low surface energy substrates such as PP, HDPE, LDPE, and the like. The poor wetting of the water-based ink compositions leads to poor adhesion of inks on the low surface energy substrates which was mainly affected by the wetting of ink on the substrate and the molecular interaction between ink and substrate.
However, in accordance with the embodiments of the present disclosure screen printing ink compositions (water-based), provides a good wetting on the plastic substrate. The optimum viscosity and optimum percentage of wetting agents provide a uniform levelling of water-based ink on the rigid plastic substrate.
In an embodiment of the present disclosure, the surface wetting agent is at least one selected from the group consisting of ethoxylated 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol, ethoxylated acetylenic diols. In an exemplary embodiment of the present disclosure, the surface wetting agent is 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol.
In a final step, predetermined amounts of a thickener, a cross-linking agent, and optionally a surface modifier is added to the fifth mixture and blended at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain the screen printing ink composition.
In an embodiment of the present disclosure, the thickener is at least one selected from the group consisting of methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and hydroxypropyl methylcellulose (HPMC). In an exemplary embodiment of the present disclosure, the thickener is hydroxypropyl methylcellulose.
In an embodiment of the present disclosure, the cross-linking agent is at least one selected from the group consisting of aziridine, poly-aziridine, trifunctional poly-aziridine, isocyanate, zinc ammonium carbonate solution. In an exemplary embodiment of the present disclosure, the cross-linking agent is aziridine.
The process of the present disclosure effectively provides a stable screen printing ink compositions (water-based) with enhanced properties.
The foregoing description of the embodiments has been provided for purposes of illustration and is not intended to limit the scope of the present disclosure. Individual components of a particular embodiment are generally not limited to that particular embodiment but are interchangeable. Such variations are not to be regarded as a departure from the present disclosure, and all such modifications are considered to be within the scope of the present disclosure.
The present disclosure is further described in light of the following experiments which are set forth for illustration purposes only and not to be construed for limiting the scope of the disclosure. The following experiments can be scaled up to industrial/commercial scale and the results obtained can be extrapolated to industrial scale.
EXPERIMENTAL DETAILS
Experiment 1: Preparation of screen printing ink composition in accordance with the present disclosure
5 gm of polyether solution was charged into a mixer followed by adding 10 gm of deionized water and blended for 15 minutes to obtain a first mixture. To the first mixture, 0.3 gm of triethanolamine (TEOA), 0.2 gm of ethoxylated C12-15 alcohol were added under stirring at a speed of 800 rpm for 15 minutes to obtain a second mixture. 8 gm of C.I. pigment yellow 12 was added to the second mixture under stirring followed by milling using a horizontal bead mill for 6 hours to obtain a pigment dispersion having a particle size of 0.5 µm to 2 µm.
The so obtained pigment dispersion was mixed with 50 gm of butyl methyl acrylate and blended at a speed of 700 rpm for 15 minutes to obtain a third mixture. To the third mixture, 15 gm of ethanol was added and blended at a speed of 700 rpm for 15 minutes to obtain a fourth mixture. 1.5 gm of silica matting agent and 2 gm of ethanediol, and 5 gm of urea were added to the fourth mixture and blended at a speed of 700 rpm for 15 minutes to obtain a fifth mixture. To the fifth mixture, 1 gm of methyl cellulose, and 2 gm of polyaziridine were added and blended at a speed of 700 rpm for 15 minutes to obtain the screen printing ink composition.
Experiment 2-5: Preparation of the screen printing ink composition in accordance with the process of the present disclosure
The screen printing ink composition was prepared similarly to the process disclosed in Experiment 1 by varying the ink composition. The composition details are provided below in Table 1.
Table 1: Composition details
Ingredients Experiment 2 Experiment 3 Experiment 4 Experiment 5
Name Amount
(mass%) Name Amount (mass%) Name Amount
(mass%) Name Amount
(mass%)
Dispersing agent Solution of Polyether 5 Solution of Polyether 3 Solution of Polyether 4 Solution of Polyether 3
Deionized water Deionized water 13.9 Deionized water 5 Deionized water 10.6 Deionized water 10
pH stabilizer Triethanolamine 0.3 Triethanolamine 0.3 Triethanolamine 0.3 Triethanolamine 0.2
Anti-foaming agent Ethoxylated C12-15 alcohol 0.3 Ethoxylated C12-15 alcohol 0.3 Ethoxylated C12-15 alcohol 0.3 Ethoxylated C12-15 alcohol 0.3
Pigment PY13 8 PY13 8 PY13 8 PY13 8
Polymer Acrylic Resin 40 Butyl Methyl Acrylate 51 Aliphatic PU resin 55 PU-Acrylic Resin 60
Co-solvent Monoethylene Glycol 15 Monoethylene Glycol 20 Monoethylene Glycol 10 Monoethylene Glycol 10
Filler Precipitated Silica 3 Precipitated Silica 1.4 Precipitated Silica 2 Precipitated Silica 1
Surface wetting agent 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol 3 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol 2 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol 1 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol 1
Softener Urea 6 Urea 5 Urea 6 Urea 4
Thickener Hydroxypropyl methyl cellulose 1.5 Hydroxypropyl methyl cellulose 1 Hydroxypropyl methyl cellulose 0.5 Hydroxypropyl methyl cellulose 0.5
Cross-linking agent Polyfunctional Aziridine 3 Polyfunctional Aziridine 2 Polyfunctional Aziridine 1.3 Polyfunctional Aziridine 1
Surface Modifier polyethylene-based wax 1 polyethylene-based wax 1 polyethylene-based wax 1 polyethylene-based wax 1

Experiment 6: Evaluation of the screen printing ink composition prepared in accordance with the present disclosure, commercial solvent-based and oil-based inks
The screen printing ink composition obtained in Experiment 1 was screen printed on a rigid plastic substrate (Thickness 1mm) having a surface energy of 40 dyne/cm) by a screen printing process. The screen printed substrates were dried at 25±3°C for 10 minutes followed by drying in a hot air oven at 60°C to 80°C for 15 minutes to completely cure the ink composition on the plastic substrate. The printed substrates were set aside for 24 hrs to allow the formation of a strong bond between the substrate and the ink composition. This time period allowed for imparting complete adhesion, scratch resistance, and chemical resistance to applied ink on the plastic substrate.
The screen printed substrates were evaluated for adhesion test, scratch resistance, suitability on various substrates, printability with respect to drying time, weatherometer (for 200hrs), screen stability, and deinking properties.
The printability properties of the screen printing ink compositions (water-based) of the present disclosure were compared with the solvent-based and the oil-based ink compositions by screen printing on a non-absorbent rigid plastic material (substrate). For the evaluation of various properties of the screen printing ink compositions of the present disclosure, the solvent-based ink composition, and the oil-based ink composition of violet, yellow, and orange were used.
Adhesion test and Scratch test:
The adhesion of the screen printing ink composition of the present disclosure was tested on substrates having surface energy below 38 dyne/cm and on substrates having surface energy above 38 dyne/cm. The results are provided in Table-2 below.
Table-2 – Adhesion test on substrates
Sr. No. Surface Energy Printed Sample Adhesion Scratch Resistance
1 Surface energy below 38dyne/cm Polyester 65 -100% Fail
2 LDPE 95-100% Pass
3 PP 95-100% Pass
1 Surface energy above 38dyne/cm Polyester 100% Pass
2 LDPE 100% Pass
3 PP 100% Pass

It is evident from the above data that the substrate materials having surface energy below 38dyne/cm have a poor adhesion of the ink compositions compared to the substrates having surface energy above 38dyne/cm.
Further, the adhesion of the screen printing ink compositions (water-based) of the present disclosure, and commercial solvent-based, oil-based ink compositions was determined according to ASTM D3359 by using 3M #610 scotch tape on various substrates. The scotch tape was 1-1.5 inches in length, was placed on the printed substrates, and manually peeled the tape to determine the degree of ink adhesion or ink removal from the substrate. The results were interpreted as percent ink adhesion. The results are provided in Table -3 below.
The scratch test was performed by placing a scratch testing tool on the surface of the printed substrate and attempting a quick scratch. A properly cured and abrasive-resistant printed ink on the substrate should not scratch. The results are provided in Table-3 below.
Table-3 – Adhesion and Scratch resistance test
Water-based Orange Seripol Sp Orange Polyfix Px Orange
Substrate Dyne level required to achieve 100% Adhesion Scratch Test Dyne level required to achieve 100% Adhesion Scratch Test Dyne level required to achieve 100% Adhesion Scratch Test
PET 44 Dynes PASS Above 38 Dynes PASS Above 38 Dynes PASS
PC Above 38 Dynes PASS Above 38 Dynes PASS Above 38 Dynes PASS
PP WHITE Above 38 Dynes PASS Above 38 Dynes PASS Above 38 Dynes PASS
PP CLEAR Above 38 Dynes PASS Above 38 Dynes PASS Above 38 Dynes PASS
LDPE 44 Dynes PASS 44 Dynes PASS 44 Dynes PASS
HDPE Above 38 Dynes PASS Above 38 Dynes PASS Above 38 Dynes PASS
ABS Above 38 Dynes PASS Above 38 Dynes PASS Above 38 Dynes PASS
PP Above 38 Dynes PASS Above 38 Dynes PASS Above 38 Dynes PASS
Polyfix: Solvent based; Seripol: Oil based screen printing ink composition
The screen printing ink composition (water-based) of the present disclosure passes the adhesion tape test as well as the scratch test on polyethylene terephthalate (PET), polycarbonate (PC), polypropylene (PP) (White, Clear), low-density polyethylene (LDPE), high-density polyethylene (HDPE), acrylonitrile butadiene styrene (ABS) and polypropylene (PP) substrates for 38 dyne/cm and 44 dyne/cm levels of the substrate. The water-based screen printing ink composition of the present disclosure provides similar results in comparison to the solvent-based ink composition and the oil-based ink composition.
Drying of screen printing ink on substrates
A single coat of the screen printing ink composition (water-based) obtained in Experiment 1 was applied on polypropylene substrate (thickness: 1mm) and the time for drying was observed. The polypropylene substrates were subjected to force drying (using infrared (IR) heating at 80°C) and air drying (at normal lab temperature of about 25°C+ 3). The results are provided below in Table-4 below
The screen printing ink composition (water-based) of the present disclosure uses acrylic emulsion having low glass transition temperature (Tg) which was more film-forming and dries at room temperature. It was observed that the screen printing ink composition of the present disclosure has a high drying speed when compared with the solvent-based ink composition. Moreover, the glycol in the screen printing ink compositions (water-based) retards the drying time thus controlled drying avoids screen clogging, provides good screen stability, and improves printability and productivity.
Table-4:
Color Product FORCE DRY
(Minutes) AIR DRY (Minutes)
ORANGE POLYFIX PX ORANGE 30 60
SERIPOL SP ORANGE 20 35
WATER-BASED ORANGE (present disclosure) 15 25

YELLOW POLYFIX PX Yellow 30 60
SERIPOL SP Yellow 20 35
WATER-BASED Yellow (present disclosure) 15 25

VIOLET POLYFIX PX VOILET 30 60
SERIPOL SP VOILET 20 35
WATER-BASED VOILET
(present disclosure) 15 25
Polyfix: Solvent based; Seripol: Oil based screen printing ink compositions
Screen stability:
The screen stability is a critical aspect that determines the printability of the ink compositions. The screen stability of the screen printing ink composition (water-based) was determined as per the method provided below
1. Step One: Take a first print on a substrate.
2. Step One: Flood the screen with ink and take the 2nd print.
3. Step Three: Wait for one minute. Again flood the screen with ink and take the 3rd print.
4. Step Four: Wait for the next two minutes, Flood the screen with ink, and take the 4th print.
5. The sequence of flooding the screen and printing is continued till they reproduce fine dots and all line details of the image.
6. No. of prints decides the screen stability.
The percentage of mono ethylene glycol, diethylene glycol, and triethylene glycol in the screen printing ink composition of the present disclosure are optimized to provide screen stability as well as to control the drying time of the printed substrate. The comparative analysis of orange, yellow, and violet colour water-based, solvent-based, and oil-based ink compositions was evaluated for screen stability. The results are provided in Table -5 below.
Table – 5:
Color Product No. of Prints
ORANGE POLYFIX PX ORANGE (Solvent Based) 4
SERIPOL SP ORANGE
(Oil Based) 4
WATER-BASED ORANGE
(Water-based) 6
YELLOW POLYFIX PX Yellow
(Solvent Based) 3
SERIPOL SP Yellow
(Oil Based) 4
WATER-BASED Yellow
(Water-based) 4
Violet POLYFIX PX Yellow
(Solvent Based) 3
SERIPOL SP Yellow
(Oil Based) 5
WATER-BASED Yellow
(Water-based) 5

It was evident that the water based screen printing ink compositions of the present disclosure have better screen stability in comparison to the oil-based ink composition and the solvent-based screen printing ink compositions.
Stability
The stability of the screen printing ink compositions (water-based) of the present disclosure was one of the most essential aspects. The functionality of the ink compositions should be consistent for a prolonged period of time i.e., shelf life. The proportion of each component in the composition affects the stability of screen printing ink compositions (water-based) during use. The stability of screen printing ink compositions (water-based) of the present disclosure was compared with solvent-based and oil-based ink compositions for three colour samples (orange, yellow, and violet).
The ink samples were kept at a constant temperature of 25 ± 3°C (humidity of 65 ± 2%) and in a hot air oven at 40 ± 2°C for 30 days.
The stability of the ink compositions was evaluated by evaluating viscosity, gloss, and lab colour information. The viscosity was determined by using a viscometer Sheen Digital Rotothinner (RT-2), and gloss was determined using a Sheen tri gloss master gloss meter according to ASTM D523 standard. The colour difference was measured by using Delta E according to DeltaECIE2000. The results are provided in Tables - 6, 7, 8, and 9.

Table 6: Viscosity
VISCOSITY (Pa.s)
COLOR PRODUCT Day 1 Day 7 Day 14 Day 21
ORANGE POLYFIX PX ORANGE 83 68 78 59
SERIPOL SP ORANGE 84 70 63 58
WATER-BASED ORANGE 3 3 3 3

YELLOW POLYFIX PX Yellow 133 142 158 160
SERIPOL SP Yellow 82 70 67 68
WATER-BASED Yellow 3 3 3 3

VOILET POLYFIX PX VIOLET 85 42 47 32
SERIPOL SP VIOLET 38 40 25 20
WATER-BASED VIOLET 3 3 3 3
Polyfix: Solvent based; Seripol: Oil based screen printing ink compositions
It was observed that the viscosity of the screen printing ink compositions (water-based) showed a constant viscosity throughout the evaluation period (three weeks) when stored at 40 ± 2°C. Further, a variation in the viscosity by at least 10-25 Pa.s was observed for all three colours of the solvent-based and the oil-based ink compositions. The variation in the viscosity indicates the fragile nature of the composition which leads to inconsistent results while printing.
Table 7: Gloss
GLOSS (60°)
COLOR PRODUCT Day 1 Day 7 Day 14 Day 21
ORANGE POLYFIX PX ORANGE 11.1 9.4 8.3 8.4
SERIPOL SP ORANGE 16.7 5.2 14 13.6
WATER-BASED ORANGE 5.8 6.8 6 5.9

YELLOW POLYFIX PX Yellow 6.8 12.6 4.7 4.4
SERIPOL SP Yellow 15.7 10.5 12.9 13
WATER-BASED Yellow 13.2 12.3 10.1 10

VOILET POLYFIX PX VOILET 8.2 5.3 6.1 8.7
SERIPOL SP VOILET 26.7 12.4 26.3 25.6
WATER-BASED VOILET 7.8 5.6 6 7.5
Polyfix: Solvent based; Seripol: Oil based screen printing ink compositions
It was observed that the screen printing ink compositions (water-based) of the present disclosure have less variation in the gloss values in comparison to the solvent-based and the oil-based ink compositions even after storing for 3 weeks.
Weatherometer
The accelerated weathering of the screen printing ink compositions of the present disclosure was determined according to ASTM G-154. The ASTM G-154 is used to evaluate the lightfastness of a material or sample.
The substrates coated with the screen printing ink compositions of the present disclosure were exposed to UV radiation and high temperatures under controlled conditions. The substrates coated with the screen printing ink composition of Example 1 were exposed to UV light (UV-B 313 lamp) for 4 hours at 60°C and a condensation cycle at 50°C for 4 hours.
After the completion of the test, the degree of colour change or fading was measured using a grey scale according to BS1006-A02:1990. The colour change or fading was indicated using a scale of 1 to 5, where 5 indicates no colour loss and 1 indicates a total colour loss. A print is considered to have failed the test if its rating falls below 3. This method is commonly used in the printing industry to evaluate the durability and lightfastness of inks and other colorants. The results are provided below in Table-8 below.
Table 8: Weatherometer
Color Product 100 HRS 200 HRS 300 HRS 400 HRS 500 HRS
ORANGE POLYFIX PX ORANGE 5 5 5 5 4-5
SERIPOL SP ORANGE 5 5 5 5 4-5
WATER-BASED ORANGE 5 5 5 5 4-5

YELLOW POLYFIX PX Yellow 5 5 5 5 4-5
SERIPOL SP Yellow 5 5 5 5 4-5
WATER-BASED Yellow 5 5 5 5 4-5

VOILET POLYFIX PX VOILET 5 5 5 5 4-5
SERIPOL SP VOILET 5 5 5 5 4-5
WATER-BASED VIOLET 5 5 5 5 4-5
Polyfix: Solvent based; Seripol: Oil base
It was observed that the screen printing ink compositions (water-based) of the present disclosure maintain the colour of the ink compositions on the substrate and avoid fading or discolouration. Thus it provides similar lightfastness in comparison to the solvent-based ink composition and the oil-based ink composition.
Colour Difference
Delta E provides the colour accuracy of the ink composition. The colour accuracy was measured by using Spectrophotometer Spectro Eye Equipment. The results are provided below in Table 9.
Table 9: DELTA E
DELTA E

COLOR PRODUCT Day 1 Day 7 Day 14 Day 21
ORANGE POLYFIX PX ORANGE L: 75.88,
a: 26.41,
b: 69.25 1.83 0.62 0.74
SERIPOL SP ORANGE L: 78.28,
a: 24.37,
b: 63.56 1.25 1.46 1.12
WATER-BASED ORANGE L: 78.08,
a: 30.38,
b: 68.77 0.4 0.65 1.29

YELLOW POLYFIX PX Yellow L: 82.79,
a: 11.86,
b: 62.1 2.2 1.25 0.34
SERIPOL SP Yellow L: 83.93,
a: 11.17,
b:71.28 1.41 1.46 1.17
WATER-BASED Yellow L:83.54,
a:15.25,
b:73.82 0.39 0.43 1.08

VOILET POLYFIX PX VOILET L:23.09,
a:23.68,
b:-27.6 0.32 0.63 2.48
SERIPOL SP VOILET L:22.72,
a:19.81,
b:-25.89 2.55 1.77 3.64
WATER-BASED VOILET L: 26.66,
a: 20.67,
b: -18.52 1.17 2.75 3.15
* wherein L = Lightness /Darkness information, a = Red / Green Information and b= Blue / Yellow Information of colour
It was observed that the water-based screen printing ink compositions of the present disclosure have a less Delta E variation in comparison to solvent-based and oil-based ink compositions.
Experiment 7: Basic Hue Preparation
The basic hue (colours) forms an important part of the colour system. This basic hue forms the basis for generating various colours and shades as desired. It was essential that these basic colours are standardized and reproducible. The present colour system was based on 12 basic hues i.e. orange, blue, green, violet, magenta, red (bluer tone), red (yellow tone), rubine red, yellow (red tone), yellow (green tone), black, and white are formulated. The composition for these basic hues are provided below in Table 10 and the colours are illustrated in Figure 2.
Table 10:
Water-based Orange/Blue/Green/Violet/Magenta/Red(B), Red(Y), Rubine Red, Yellow(Re), Yellow(G), Black and White
Ingredient Amount
(mass %)
Pigment (White Pigmen/ Black Pigment / Red Pigment / Green Pigment / Blue Pigment / Violet Pigment / Orange Pigment / Yellow Pigment) 5-10
Polyether solution 2-5
Deionized water 5-15
Triethanolamine 0.2-0.5
Ethoxylated C12-15 Alcohol 0.1-0.5
Butyl methyl acrylate 40-60
Monoethylene glycol 10-20
Precipitated silica 1-3
2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol 0.5-3
Urea 3-8
Polyfunctional aziridine 1-3
Hydroxypropyl methyl cellulose (HPMC) 0.1-2

These basic twelve special colours were used to match any Pantone colour. These inks are made for the purpose of being used to mix in a specific proportion and create PMS (Pantone Matching System) colours as desired by the user.
Experiment 8: Hazardous materials analysis
The water-based ink composition of the present disclosure was evaluated for the presence of hazardous materials. It is observed from the results that the amounts of Cadmium, Lead, Mercury, Hexavalent chromium, Polybrominated biphenyls (PBBs), Polybrominated diphenyl ethers (PBDEs), and Phthalates such as Bis(2-ethylhexyl) phthalate (DEHP), Butyl benzyl phthalate (BBP), Dibutyl phthalate (DBP) and Diisobutyl phthalate (DIBP) comply with the limits as set by Restriction of Hazardous Substances (RoHS) Directive (EU) 2015/863 amending Annex II to Directive 2011/65/EU.
Thus the water based screen printing ink compositions of the present disclosure are environment friendly.

TECHNICAL ADVANCEMENTS
The present disclosure described hereinabove has several technical advantages including, but not limited to, the realization of a screen printing ink composition (water-based) that:
• reduces the ink cost as compared to solvent and UV ink systems.
• is devoid of volatile organic compounds;
• is suitable for a wide variety of plastic substrates and containers;
• has good ink storage stability, good screen stability, excellent print quality, and good adhesion with the plastic substrate or plastic container having a surface tension of above 38 dyne/cm;
• has good levelling, scratch, and water resistance;
• has improved adhesion and drying time;
• is economical and environmentally friendly;
• reduces environmental pollution; and
• provides uniform printing;
a process for a preparing screen printing ink composition that is:
• is simple, environment-friendly, and cost-efficient.
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the following description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
The foregoing description of the specific embodiments so fully reveals the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the embodiments as described herein.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles or the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations, and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions, or quantities fall within the scope of the disclosure unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the components and component parts of the preferred embodiments, it will be appreciated that many embodiments can be made and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other changes in the preferred embodiment, as well as other embodiments of the disclosure, will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.
,CLAIMS:WE CLAIM:
1. A screen printing ink composition comprising:
a. a polymer in an amount in the range of 40 mass% to 60 mass% with respect to the total mass of the composition;
b. a pigment in an amount in the range of 5 mass% to 10 mass% with respect to the total mass of the composition;
c. a dispersing agent in an amount in the range of 2 mass% to 5 mass% with respect to the total mass of the composition;
d. a softener in an amount in the range of 3 mass% to 8 mass% with respect to the total mass of the composition;
e. a surface wetting agent in an amount in the range of 0.5 mass% to 3 mass% with respect to the total mass of the composition;
f. a pH stabilizer in an amount in the range of 0.2 mass% to 0.5 mass% with respect to the total mass of the composition;
g. an anti-foaming agent in an amount in the range of 0.1 mass% to 0.5 mass% with respect to the total mass of the composition;
h. a cross-linking agent in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the composition;
i. a filler in an amount in the range of 1 mass% to 3 mass% with respect to the total mass of the composition;
j. a thickener in an amount in the range of 0.1 mass% to 2 mass% with respect to the total mass of the composition;
k. a co-solvent in an amount in the range of 10 mass% to 20 mass% with respect to the total mass of the composition;
l. optionally a surface modifier in an amount in the range of 0.5 mass% to 2 mass% with respect to the total mass of the composition; and
m. q.s. deionized water.
2. The composition as claimed in claim 1, wherein said polymer is at least one selected from the group consisting of acrylic resin, PU acrylic resin, acrylic copolymer resin, PU resin, and aliphatic PU resin.
3. The composition as claimed in claim 2, wherein said acrylic resin is at least one selected from the group consisting of butyl methyl acrylate, styrene acrylic emulsion, methyl acrylate, polymethyl methacrylate (PMMA), and styrene acrylate.
4. The composition as claimed in claim 2, wherein said acrylic resin is characterized by having
a. solids in an amount in the range of 35% to 45%;
b. a glass transition temperature (Tg) in the range of -10°C to 100°C; and
c. an acid number in the range of 10 mg KOH/g to 90 mg KOH/g.
5. The composition as claimed in claim 2, wherein said aliphatic resin is at least one selected from the group consisting of aliphatic polyester polyurethane, aliphatic acrylic polyurethane, aliphatic polyether polyurethane, and aliphatic polyurethane dispersion.
6. The composition as claimed in claim 1, wherein said pigment is at least one selected from the group consisting of C.I. pigment yellow 12 (PY12), C.I. pigment yellow 13 (PY13), C.I. pigment yellow 14 (PY14), monoazo yellow (PY74), disazopyrazolone orange (PO13), benzidine pigment orange R (PO16), C.I. pigment orange 46 (PO46), C.I. pigment red 2 (PR2), C.I. pigment red 2 (PR3), C.I. pigment red 4 (PR4), C.I. pigment red 12 (12), C.I. pigment red 48, pigment red 48:1 (CB1855357), pigment red 48:2, pigment red 53, pigment red 57:2, pigment green 7 (PG7), pigment green 2 (PG2), phthal green 36 (PG36), pigment blue 15:2 (PB15:2), pigment blue 15:3 (PB15:3), pigment blue 15:6 (PB15:6), pigment blue 16, pigment blue 29, pigment blue 56, pigment blue 61, triarylcarbonium violet (PV3), pigment violet 37 (PV37), C.I. Pigment Black 6 (PB6), C.I. Pigment Black 7 (PB7), C.I. pigment white 6 (PW6), C.I. pigment white 7 (PW7), C.I. pigment white 18 (PW18), and C.I. pigment white 26 (PW26).
7. The composition as claimed in claim 1, wherein said dispersing agent is at least one selected from the group consisting of modified styrene-maleic acid copolymer solution, polyether solution, acrylic resin solution, mono propylene glycol, dipropylene glycol, tri-propylene glycol, mono-ethylene glycol, and diethylene glycol.
8. The composition as claimed in claim 1, wherein said softener is at least one selected from the group consisting of urea, hydroxyethyl ethylene urea, and alkylated urea.
9. The composition as claimed in claim 1, wherein said surface wetting agent is at least one selected from the group consisting of ethoxylated 2,4,7,9-tetramethyldec-5-yne-4,7-diol, ethanediol, and ethoxylated acetylenic diols.
10. The composition as claimed in claim 1, wherein said pH stabilizer is at least one selected from the group consisting of triethanolamine, ammonia, 2-amino-methyl-1-propanol, and NaOH.
11. The composition as claimed in claim 1, wherein said anti-foaming agent is at least one selected from the group consisting of acetylene glycol derivative, ethoxylated C12-15 alcohols, and propoxylated C12-15 alcohols.
12. The composition as claimed in claim 1, wherein said cross-linking agent is at least one selected from the group consisting of aziridine, polyaziridine, aliphatic isocyanates, zinc ammonium carbonate solution, and trifunctional polyaziridine.
13. The composition as claimed in claim 1, wherein said filler is at least one selected from the group consisting of silicon dioxide, silica matting agent, precipitated silica, and pyrogenic silica.
14. The composition as claimed in claim 1, wherein said thickener is at least one selected from the group consisting of methylcellulose, ethyl cellulose, hydroxyethyl cellulose, carboxymethyl cellulose, and hydroxypropyl methylcellulose (HPMC).
15. The composition as claimed in claim 1, wherein said co-solvent is at least one selected from the group consisting of monoethylene glycol, propylene glycol, isopropyl alcohol, ethanol, and aqueous ethanol.
16. The composition as claimed in claim 1, wherein said surface modifier is at least one selected from the group consisting of polyethylene-based wax, paraffin base wax, polysiloxane, polyether modified siloxane, hydroxy-functionalized polydimethylsiloxane, and polyether modified siloxane.
17. The composition as claimed in claim 1, wherein a weight ratio of said polymer to said cross-linking agent is in the range of 1:0.025 to 1:0.07.
18. The composition as claimed in claim 1, wherein a weight ratio of said polymer to said dispersing agent is in the range of 1:0.05 to 1:0.09.
19. The composition as claimed in claim 1, wherein said screen printing ink composition is suitable for printing on a substrate, wherein said substrate is selected from flame treated polypropylene, corona-treated polypropylene (PP), high-density polyethylene (HDPE), low-density polyethylene (LDPE), polyethylene terephthalate (PET), polycarbonate (PC), and acrylonitrile butadiene styrene (ABS).
20. The composition as claimed in claim 19, wherein said substrate is characterized by having a surface energy in the range of 38 dyne/cm to 48 dyne/cm.
21. A process for the preparation of a screen printing ink composition as claimed in claim 1, said process comprising the following steps:
a. blending a predetermined amount of a dispersing agent and deionized water for a first predetermined time period to obtain a first mixture;
b. adding a predetermined amounts of a pH stabilizer and an anti-foaming agent to said first mixture and blending at a speed in the range of 500 rpm to 1000 rpm for a second predetermined time period to obtain a second mixture;
c. adding a predetermined amount of a pigment to said second mixture followed by milling for a third predetermined time period to obtain a pigment dispersion with a particle size in the range of 0.1 µm to 2 µm;
d. adding a predetermined amount of a polymer to said pigment dispersion and blending at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a third mixture;
e. adding a predetermined amount of a co-solvent to said third mixture and blending at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a fourth mixture;
f. adding a predetermined amount of a filler and a surface wetting agent, a softener to said fourth mixture and blending at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain a fifth mixture; and
g. adding a thickener, a cross-linking agent, and optionally a surface modifier to said fifth mixture and blending at a speed in the range of 500 rpm to 800 rpm for a time period in the range of 10 minutes to 20 minutes to obtain said screen printing ink composition.
22. The process as claimed in claim 21, wherein said first predetermined time period is in the range of 10 minutes to 20 minutes.
23. The process as claimed in claim 21, wherein said second predetermined time period is in the range of 10 minutes to 20 minutes.
24. The process as claimed in claim 21, wherein said third predetermined time period is in the range of 4 hours to 9 hours.

Dated this 19th day of May, 2023

_______________________________
MOHAN RAJKUMAR DEWAN, IN/PA – 25
of R.K.DEWAN & CO.
Authorized Agent of Applicant

TO,
THE CONTROLLER OF PATENTS
THE PATENT OFFICE, AT MUMBAI