Ink

Abstract

Disclosed is an ink comprising: (a) a solvent composition; and (b) a pigment dispersion; wherein the solvent composition comprises soybean methyl ester, diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate, the soybean methyl ester being present in an amount of 30% to 75% by weight based on the total weight of the ink, and wherein the pigment dispersion comprises a pigment and a binder, the binder comprises a poly (vinyl chloride-vinyl acetate) copolymer. A process for producing the ink, a printing method, and a printed article are also disclosed.

Description

Technical Field

[0001] This invention relates to inks, ink production processes, printing methods, and printed products. Background Technology

[0002] Inkjet printing is used in a wide range of printing applications and can deliver high-resolution images on a range of substrates. The growing interest in safety and environmentally friendly technologies has led to an increased demand for inks using harmless components that pose little or no risk to the environment. Furthermore, the use of volatile components (such as certain solvents) in inks is considered undesirable because significant evaporation of such components or solvents can cause the ink to dry in the printhead, resulting in poor nozzle recoverability. Due to evaporation, the viscosity of the ink can also easily change over time. Changes in viscosity over time will render the ink unsuitable for inkjet printing. Summary of the Invention

[0003] Technical issues

[0004] Providing inks that offer advantages in desired viscosity stability and evaporation characteristics, exhibit good nozzle recovery in inkjet printing, and do not use volatile, hazardous, or environmentally harmful solvents remains a particular issue.

[0005] Therefore, new inks are needed to solve the above problems.

[0006] Solution to the problem

[0007] This invention provides an ink comprising:

[0008] (a) Solvent composition; and

[0009] (b) Pigment dispersions;

[0010] The solvent composition comprises soy methyl ester, diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate, wherein the soy methyl ester is present in an amount of 30% to 75% by weight based on the total weight of the ink;

[0011] The pigment dispersion comprises a pigment and a binder, wherein the binder comprises a poly(vinyl chloride-vinyl acetate) copolymer.

[0012] The present invention further provides a process for preparing ink, comprising:

[0013] (A) Mixing a pigment dispersion with a first portion of a solvent composition comprising diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate to form a first mixture; and

[0014] (b) combining the first mixture with a second part solvent composition comprising soy methyl ester and optionally comprising diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate,

[0015] to form an ink.

[0016] The present invention further provides a printing method comprising:

[0017] - providing an ink; and

[0018] - printing the ink onto a substrate using an inkjet printer.

[0019] The present invention further provides a printed article comprising a substrate and an ink.

[0020] The present inventors have surprisingly found that the inclusion of soy methyl ester in a solvent composition of an ink as described above (the ink further comprising a pigment dispersion as described above) results in an ink that provides the desired viscosity stability and evaporation characteristics, and that also exhibits good nozzle recovery in inkjet printing, and that does not use volatile, hazardous, or environmentally harmful solvents. DETAILED DESCRIPTION

[0021] Ink

[0022] The present invention provides an ink comprising:

[0023] (a) a solvent composition; and

[0024] (b) a pigment dispersion;

[0025] wherein the solvent composition comprises soy methyl ester, diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0026] The ink of the present invention comprises a solvent composition comprising soy methyl ester, diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0027] The ink of the present invention typically does not comprise a volatile, hazardous, or environmentally harmful solvent.

[0028] The ink of the present application typically does not comprise a solvent classified as flammable, corrosive or hazardous. As part of their common general knowledge, the skilled person will understand which substances are classified as flammable, corrosive or hazardous and suitable solvent classifications include which of the following: Globally Harmonized System of Classification and Labelling of Chemicals (GHS); Fourth revised edition, United Nations New York and Geneva, 2011.

[0029] Preferably, the ink of the present application does not comprise one or more solvents selected from cyclohexanone, butyl glycol acetate and methoxy propanol acetate.

[0030] The ink of the present application typically has desirable evaporation properties. The ink of the present application typically does not comprise a solvent which shows 1% or more evaporation by weight at 30°C over 16 hours, for example as determined by the following method:

[0031] - Weigh 2 g of test material into an open container (50 mm diameter);

[0032] - Place into an oven set to 30°C for a 16 hour period; and

[0033] - Assess the weight loss at the end of the 16 hour period.

[0034] The ink of the present application typically does not comprise a solvent which shows 1% or more evaporation by weight at 150°C, for example as determined by the following method:

[0035] - Use a moisture analyser (e.g. Ohaus MB45) and set the temperature to 150°C;

[0036] - Weigh 2 g of test material into a tray on the balance,

[0037] - Close the lid.

[0038] - Terminate the test when the amount changes by 0.001 g within 60 seconds.

[0039] Preferably, the ink of the present application does not comprise one or more solvents selected from cyclohexanone, butyl glycol acetate, methoxy propanol acetate, propylene glycol diacetate and dimethyl adipate.

[0040] The solvent composition comprises diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate. Typically, the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is from 20 to 65 weight percent based on the total weight of the ink, for example, from 20 to 59 weight percent based on the total weight of the ink, or from 20 to 56 weight percent based on the total weight of the ink, or from 20 to 55 weight percent based on the total weight of the ink. Preferably, the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is from 28 to 59 weight percent based on the total weight of the ink, for example, from 28 to 56 weight percent based on the total weight of the ink, or from 28 to 55 weight percent based on the total weight of the ink. More preferably, the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is from 28 to 46 weight percent based on the total weight of the ink.

[0041] As used herein, the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate by weight based on the total weight of the ink refers to the combined weight of the diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate components relative to the total weight of the ink. For example, if diisobutyl succinate is present in an amount of 8 weight percent based on the total weight of the ink, diisobutyl glutarate is present in an amount of 10 weight percent based on the total weight of the ink, and diisobutyl adipate is present in an amount of 12 weight percent based on the total weight of the ink, then the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate based on the total weight of the ink will be 30 weight percent.

[0042] Diisobutyl succinate is typically present in an amount of 15 to 30 weight percent based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate. Diisobutyl glutarate is typically present in an amount of 55 to 70 weight percent based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate. Diisobutyl adipate is typically present in an amount of 8 to 25 weight percent based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0043] Preferably, diisobutyl succinate is present in an amount of 15 to 30 weight percent based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate; diisobutyl glutarate is present in an amount of 55 to 70 weight percent based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate; and diisobutyl adipate is present in an amount of 8 to 25 weight percent based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0044] Diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate can be provided as commercially available solvent mixtures, for example Coasol (Registered Trademark) available from Chemoxy International Ltd and Saiper Chemicals Pvt Ltd.

[0045] The solvent composition comprises soya methyl ester. Soya methyl ester is derived from an acid (hereinafter, acid component of soya methyl ester) and an alcohol (hereinafter, alcohol component of soya methyl ester).

[0046] The acid component of soya methyl ester is an unsaturated fatty acid. Preferably, the acid component of soya methyl ester is a di-unsaturated fatty acid. Di-unsaturated fatty acids can be obtained, for example, by hydrolysis of a vegetable oil, for example soya oil. Examples of suitable di-unsaturated fatty acids include linoleic acid, eicosadienoic acid and docosadienoic acid. As the acid component of the first ester, linoleic acid is preferred. Linoleic acid can be obtained by hydrolysis of soya oil.

[0047] The alcohol component of the first ester is a monohydric alcohol. Examples of suitable monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol and t-butanol. Methanol is the alcohol component of soya methyl ester.

[0048] Soya methyl ester can be an ester of a di-unsaturated fatty acid and a monohydric alcohol, and examples of soya methyl ester include, for example, methyl esters of linoleic acid, eicosadienoic acid, docosadienoic acid and linolelaidic acid. As soya methyl ester, methyl linoleate is preferred.

[0049] In the ink of the present application, soya methyl ester is present in an amount of 30% to 75% by weight, based on the total weight of the ink. Typically, soya methyl ester is present in an amount of 30% to 68% by weight, based on the total weight of the ink. Preferably, soya methyl ester is present in an amount of 40% to 68% by weight, based on the total weight of the ink. More preferably, soya methyl ester is present in an amount of 50% to 68% by weight, based on the total weight of the ink.

[0050] The solvent composition can further comprise an ester, a glycol ester, a glycol ester acetate, a glycol ether, a glycol ether acetate, a lactone, an adipate, a succinate, a glutarate or a mixture thereof.

[0051] The ink of the present application comprises a pigment dispersion. The pigment dispersion comprises a pigment and a binder. Unless otherwise stated, the term pigment dispersion as used herein typically means a pigment and a binder. However, it will be appreciated that the pigment is typically present in the form of a dispersion throughout the entire ink.

[0052] The pigments used in the pigment dispersion in the ink of the present application are not particularly limited. Typically, the pigment dispersion comprises a black pigment, a blue pigment, a green pigment, a violet pigment, a red pigment, a brown pigment, a yellow pigment, or a white pigment, or a mixture thereof. The pigment can be a black pigment. The pigment can be a white pigment. The pigment can be a color pigment (i.e. a non-black or non-white pigment, such as cyan, red or yellow). The pigment dispersion can comprise a mixture of pigments. Preferably, the pigment dispersion comprises a pigment selected from Pigment Black 7, Pigment Blue 15:3, Pigment Blue 60, Pigment Green 7, Pigment Violet 37, Pigment Red 144, Pigment Red 166, Pigment Red 185, Pigment Red 254, Pigment Brown 23, Pigment Yellow 83, Pigment Yellow 93, Pigment Yellow 110, Pigment Yellow 151, Pigment White 7, or a mixture thereof.

[0053] The pigment typically has a number average particle size (Dn50) of 0.020 pm to 0.150 pm, as measured by disc centrifugation, for example as measured using a CPS DC24000 disc centrifuge particle sizer.

[0054] The pigment typically has a volume average particle size characterized by:

[0055] (a) a Dv50 of 110 to 120 nm; and / or

[0056] (b) a Dv90 of less than 350 nm;

[0057] as measured by dynamic light scattering, for example as measured using a Malvern Zetasizer Nano-ZS dynamic light scattering particle sizer.

[0058] The binder used in the pigment dispersion in the ink of the present application is also not particularly limited. The binder comprises a poly(vinyl chloride-vinyl acetate) copolymer. The poly(vinyl chloride-vinyl acetate) copolymer can have a random copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer can have an alternating copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer can have a block copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer can have a graft copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer can have a vinyl chloride:vinyl acetate monomer ratio of 80:20 to 90:10 (typically weight:weight). The poly(vinyl chloride-vinyl acetate) copolymer can have a molecular weight (Mw) of 40000 g mol -1 to 50000 g mol -1 The molecular weight (Mw) can be measured by methods well known to the skilled person, for example according to ISO 16014-3:2019.

[0059] The ratio of binder (e.g. the above-mentioned poly(vinyl chloride-vinyl acetate) copolymer) to pigment is typically 30:70 to 70:30 (typically weight:weight), for example 40:60 to 60:40 (typically weight:weight), 40:60 to 55:45 (typically weight:weight), or about 50:50 (typically weight:weight), or about 48:52 (typically weight:weight), or about 49:51 (typically weight:weight), or about 44:56 (typically weight:weight).

[0060] The pigment dispersion can be a commercially available pigment dispersion. Examples of commercially available pigment dispersions that can be used in the inks of the present application include the Microlith (Registered Trademark) - K series available from BASF SE (e.g. Yellow 1040 K, Yellow 1061 K, Yellow 1550 K, Yellow 2040 K, Brown 3001 K, Scarlet 3430 K, Red 3630 K, Red 3890 K, Red 4410 K, Violet 5700 K, Blue 6480 K, Blue 7080 K, Green 8750 K, Black 0066 K and White 0022 K).

[0061] The pigment dispersion can be present in an amount of 1 to 40% by weight based on the total weight of the ink, for example when the pigment dispersion comprises a white pigment. The pigment dispersion can be present in an amount of 1 to 20% by weight based on the total weight of the ink, for example when the pigment dispersion comprises a coloured pigment. Preferably, the pigment dispersion is present in an amount of 1 to 10% by weight based on the total weight of the ink, for example 1 to 6%, 1 to 4% by weight, 2 to 6%, 3 to 5% or about 4% based on the total weight of the ink. As mentioned above, the amount of the above-mentioned pigment dispersion is typically the total amount of pigment and binder.

[0062] Typical inks of the present application include those wherein:

[0063] - the total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is 20 to 65% by weight based on the total weight of the ink;

[0064] - the soy methyl ester is present in an amount of 30 to 75% by weight based on the total weight of the ink; and

[0065] - the pigment dispersion is present in an amount of 3 to 5% by weight based on the total weight of the ink.

[0066] Further typical inks of the present application include those wherein:

[0067] - the total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is from 28% to 59% by weight based on the total weight of the ink;

[0068] - soy methyl ester is present in an amount of from 30% to 68% by weight based on the total weight of the ink; and

[0069] - the pigment dispersion is present in an amount of from 3% to 5% by weight based on the total weight of the ink.

[0070] Preferred inks of the present application include those wherein:

[0071] - the total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is from 28% to 56% by weight based on the total weight of the ink;

[0072] - soy methyl ester is present in an amount of from 40% to 68% by weight based on the total weight of the ink;

[0073] - the pigment dispersion is present in an amount of from 3% to 5% by weight based on the total weight of the ink.

[0074] Particularly preferred inks of the present application include those wherein:

[0075] - the total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is from 28% to 46% by weight based on the total weight of the ink;

[0076] - soy methyl ester is present in an amount of from 50% to 68% by weight based on the total weight of the ink;

[0077] - the pigment dispersion is present in an amount of from 3% to 5% by weight based on the total weight of the ink.

[0078] Preferred cyan inks of the present application include those wherein the pigment is pigment blue 15:3, and wherein:

[0079] - the total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is from 27% to 57% by weight based on the total weight of the ink;

[0080] - soy methyl ester is present in an amount of from 39% to 69% by weight based on the total weight of the ink; and

[0081] - the pigment dispersion is present in an amount of from 3% to 5% by weight based on the total weight of the ink.

[0082] The particularly preferred cyan inks of the present invention include those comprising: wherein the pigment is pigment blue in a 15:3 ratio, and wherein:

[0083] - The total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is 36% to 47% by weight based on the total weight of the ink;

[0084] - Soy methyl ester is present in an amount of 49% to 60% by weight, based on the total weight of the ink;

[0085] - The pigment dispersion is present in an amount of 3% to 5% by weight, based on the total weight of the ink.

[0086] The preferred red inks of the present invention include those comprising: wherein the pigment is Pigment Red 166, and wherein:

[0087] - The total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is 33% to 47% by weight based on the total weight of the ink;

[0088] - Soybean methyl ester is present in an amount of 49% to 63% by weight, based on the total weight of the ink; and

[0089] - The pigment dispersion is present in an amount of 3% to 5% by weight, based on the total weight of the ink.

[0090] The particularly preferred red inks of the present invention include those whose pigment is Pigment Red 166, and wherein:

[0091] - The total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is 33% to 44% by weight based on the total weight of the ink;

[0092] - Soy methyl ester is present in an amount of 52% to 63% by weight, based on the total weight of the ink;

[0093] - The pigment dispersion is present in an amount of 3% to 5% by weight, based on the total weight of the ink.

[0094] The preferred yellow inks of the present invention include those comprising: wherein the pigment is Pigment Yellow 110, and wherein:

[0095] - The total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is 21% to 47% by weight based on the total weight of the ink;

[0096] - Soybean methyl ester is present in an amount of 49% to 75% by weight, based on the total weight of the ink; and

[0097] - the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is 36% to 47% by weight based on the total weight of the ink;

[0098] Particularly preferred yellow inks of the present application include those wherein the pigment is Pigment Yellow 110, and wherein:

[0099] - the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is 36% to 47% by weight based on the total weight of the ink;

[0100] - soy methyl ester is present in an amount of 49% to 60% by weight based on the total weight of the ink;

[0101] - the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0102] Preferred black inks of the present application include those wherein the pigment is Pigment Black 7, and wherein:

[0103] - the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is 21% to 66% by weight based on the total weight of the ink;

[0104] - soy methyl ester is present in an amount of 30% to 75% by weight based on the total weight of the ink; and

[0105] - the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0106] Particularly preferred black inks of the present application include those wherein the pigment is Pigment Black 7, and wherein:

[0107] - the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is 24% to 34% by weight based on the total weight of the ink;

[0108] - soy methyl ester is present in an amount of 62% to 72% by weight based on the total weight of the ink;

[0109] - the pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0110] The inks of the present application typically have a viscosity that is desirable for inkjet printing. Preferably, the viscosity of the ink is 7 to 20 cP at 25°C. More preferably, the viscosity of the ink is 8 to 14 cP at 25°C. Viscosity can be measured as using a cone and plate viscometer, such as a Brookfield DV3T viscometer with a CPA-40Z cone operating at 10 rpm.

[0111] The inks of the present application exhibit good nozzle recovery. Typically, the inks show no loss in nozzle firing after a period of at least 4 days idle at jetting temperature, as determined using a Ricoh Gen5 printhead (MH5420) by the following method.

[0112] The inks of the present application exhibit good wash resistance. Typically, the inks show very little change in colour after 5 cycles of washing at 40°C, as determined by the following method.

[0113] Ink preparation process

[0114] The present application provides a process for preparing an ink according to the present application, comprising:

[0115] (a) mixing a pigment dispersion with a first part solvent composition comprising diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate to form a first mixture; and

[0116] (b) mixing the first mixture with a second part solvent composition comprising soy methyl ester and optionally diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate,

[0117] to form an ink.

[0118] The components of the first part solvent composition can be added separately. The components of the first part solvent composition can be added simultaneously. The components of the first part solvent composition can be added sequentially.

[0119] The components of the second part solvent composition can be added separately. The components of the second part solvent composition can be added simultaneously. The components of the second part solvent composition can be added sequentially.

[0120] Typically, step (a) of mixing a pigment dispersion with a first part solvent composition comprises adding the pigment dispersion to a vortex of the first part solvent composition in a dissolver having a tip speed of 9 metres per second or more (e.g. 9 to 15 metres per second, 10 to 12 metres per second or about 10 metres per second) and mixing for 5 to 25 minutes (e.g. 8 to 22 minutes, 10 to 20 minutes, or about 15 minutes).

[0121] Typically, step (b) of combining the first mixture with a second portion of the solvent composition comprises adding the second portion of the solvent composition to a vortex of the first mixture in a dissolver having a tip speed of 1 to 8 meters per second (e.g. 2 to 7 meters per second or 3 to 6 meters per second) and mixing for 5 to 15 minutes (e.g. 7 to 13 minutes, 9 to 11 minutes or about 10 minutes). Preferably, step (b) comprises adding the second portion of the solvent composition to a vortex of the first mixture in a dissolver having a tip speed of 3 to 6 meters per second and mixing for about 10 minutes.

[0122] Printing method

[0123] The general process of inkjet printing is well known to the skilled person. The inks of the present application have been described herein and therefore the skilled person can readily apply the inks in an inkjet printing process based on their common general knowledge.

[0124] The present application also relates to a printing process. The present application provides a printing process comprising:

[0125] - providing an ink of the present application; and

[0126] - printing the ink onto a substrate using an inkjet printer.

[0127] The substrate used in the printing process is not particularly limited. The substrate can be formed from paper, non-woven fabric, plastic, wood, metal or a combination of these materials. Particular examples can be selected from natural paper, plastic film, synthetic paper, non-woven fabric, fleece, cloth, wood, semi-solidified wallpaper (where a solid resin layer is present in semi-gel form), full solidified wallpaper, metal sheet, and metal foil or any combination of these materials. The substrate can comprise a fleece backing paper. The substrate can be semi-rigid polyvinyl chloride suitable for use in flooring applications. The substrate can be polyethylene suitable for use in packaging applications.

[0128] A multi-layered substrate can be used. Preferably, the top layer of the substrate is selected from paper, plastic film (e.g. polyvinyl chloride), wood or metal (e.g. aluminium).

[0129] Printed article

[0130] The present application also relates to a printed article. The present application provides a printed article comprising a substrate and an ink of the present application. The printed article of the present application can be a textile. The substrate in the printed article of the present application can be as described above with reference to the substrate in the printing process of the present application.

[0131] The printed article of the present application can be a flooring article. The printed article of the present application can be a wallpaper.

[0132] As described above, the printed article of the present application can be obtainable by the printing method of the present application.

[0133] The present application is illustrated below by the following non-limiting examples.

[0134] Examples

[0135] Inks having the compositions listed below in Table 1 (cyan ink), Tables 2 and 5 (red ink), Tables 3 and 6 (yellow ink), and Table 4 (black ink) were prepared according to the following procedure.

[0136] Stage 1 - Add the first portion of solvent composition of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate to a disperser and then stir at a tip speed of 9 m sec -1 -1 to create a vortex. Add the pigment dispersion to the vortex of the first portion of solvent composition and stir for 10 to 20 minutes while maintaining a tip speed of 9 m sec

[0137] Stage 2 - Reduce the tip speed to 3 to 6 m sec -1 -1 and add the second portion of solvent composition of soy methyl ester to the vortex of the Stage 1 composition and stir for 10 minutes.

[0138] Inks were analyzed for viscosity stability and nozzle recovery.

[0139] A Brookfield DV3T Cone and Plate Viscometer was suitable for determining the viscosity of the inks. A Brookfield DV3T viscometer with a CPA-40Z cone operating at 10 rpm was used to determine the viscosity. The viscosity was measured as follows: at room temperature for a period of six months, at 50 °C for a period of two weeks, at room temperature for a period of one year, and at 30 °C for a period of six months.

[0140] The viscosity stability of the inks was rated as follows: “Excellent” if less than 10% change in viscosity was recorded, “Very Good” if 10% to 20% change in viscosity was recorded, “Good” if 20% to 30% change in viscosity was recorded, “Fair” if 30% to 50% change in viscosity was recorded, and “Poor” if greater than 50% change in viscosity was recorded or if separation of the ink was recorded.

[0141] Nozzle recovery was evaluated using a Ricoh Gen5 printhead (MH5420). The ink was delivered from the bottle without reverse channel flow. A 9 pL droplet was used. The firing frequency was 20 kHz. The firing temperature was 30 °C. The following method was used:

[0142] 1) Print a nozzle matrix test pattern on plain paper.

[0143] 2) Check that all nozzles (1280) are jetting.

[0144] 3) Stop jetting.

[0145] 4) Leave the print head at jetting temperature for 4 days.

[0146] 5) Restart jetting and print the nozzle matrix test pattern, checking that all nozzles (1280) are jetting.

[0147] The print head is not used for washing, wiping or capping during the nozzle recovery test.

[0148] The nozzle recovery is evaluated and rated as "Excellent Excellent", "Very Good", "Good", "Fair" or "Poor".

[0149] The amounts of the components shown in Tables 1 to 6 are weight percentages. The components used and the analytical results are as follows:

[0150] Pigment dispersion: Microlith (Registered Trademark) - K series (Microlith Blue 7080 K, 50:50 weight:weight dispersion of pigment in a vinyl chloride / vinyl acetate binder, or Microlith Black 0066 K, 48:52 weight:weight dispersion of pigment in a vinyl chloride / vinyl acetate binder, or Microlith Yellow 2040 K, 49:51 weight:weight dispersion of pigment in a vinyl chloride / vinyl acetate binder, or Microlith Maroon 3430 K, 44:56 weight:weight dispersion of pigment in a vinyl chloride / vinyl acetate binder).

[0151] Coasol (Registered Trademark): mixture of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate

[0152] SME: soy methyl ester

[0153] [Table 1]

[0154]

[0155] [Table 2]

[0156]

[0157] [Table 3]

[0158]

[0159] [Table 4]

[0160]

[0161] [Table 5]

[0162]

[0163] [Table 6]

[0164]

[0165] As can be seen from the evaluations listed in the table above, the inks of the present invention exhibit excellent viscosity stability and excellent nozzle recoverability after short-term and long-term storage at temperatures including room temperature and elevated temperatures.

[0166] In addition, color changes due to washing were examined using inks (cyan ink 4 (Table 1), yellow ink 5 (Table 3), and black ink 2 (Table 4)). Printing was performed using a Ricoh Gen5 printhead (MH5420). Ink was delivered directly from the bottle without any reverse flow. 10-20 pL droplets were used. The jetting frequency was 20 kHz. As substrates, cotton fabric (RTPApparel, Aeoon Technologies, 100% cotton), cotton yarn (Guterman CA02776, 100% cotton), polyester fabric (Polx SWSE wipes, 100% polyester), and polyester yarn (Coats Sylko AW, 100% polyester) were used. After printing, the ink and substrate were exposed to 200°C. Then, five cycles of washing were performed at 40°C according to the ISO105-C06 procedure. Afterward, color measurements were performed using SpectroDens (Techkon GmbH).

[0167] Based on the color measurement, it was observed that the color change of the ink due to washing was very small (DE2000<3).

[0168] As can be seen from the above evaluation, the ink of the present invention has excellent wash resistance.

[0169] The invention has been described above with reference to some embodiments. However, these embodiments are merely illustrative, and those skilled in the art will understand that various modifications are possible, including combinations of features described above with reference to individual embodiments, without departing from the scope of the invention as defined in the appended claims (and their equivalents are properly considered).

[0170] This application is based on and claims priority to UK Patent Application No. 2314902.4, filed on 28 September 2023, UK Patent Application No. 2314905.7, and UK Patent Application No. 2314906.5, filed on 28 September 2023, the entire contents of which are incorporated herein by reference.

Claims

1. Ink, which includes: (a) Solvent composition; and (b) Pigment dispersions; The solvent composition comprises soy methyl ester, diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate, wherein the soy methyl ester is present in an amount of 30% to 75% by weight based on the total weight of the ink; The pigment dispersion comprises a pigment and a binder, wherein the binder comprises a poly(vinyl chloride-vinyl acetate) copolymer.

2. The ink according to claim 1, wherein the ink is black ink, cyan ink, blue ink, green ink, purple ink, red ink, brown ink, yellow ink, or white ink, or a mixture thereof.

3. The ink according to claim 1 or 2, wherein the pigment is selected from pigment black 7, pigment blue 15:3, pigment blue 60, pigment green 7, pigment purple 37, pigment red 144, pigment red 166, pigment red 185, pigment red 254, pigment brown 23, pigment yellow 83, pigment yellow 93, pigment yellow 110, pigment yellow 151, pigment white 7, or mixtures thereof.

4. The ink according to any one of claims 1 to 3, wherein soy methyl ester is present in an amount of 30% to 68% by weight of the total weight of the ink, preferably 40% to 68% by weight of the total weight of the ink, and more preferably 50% to 68% by weight of the total weight of the ink.

5. The ink according to any one of claims 1 to 4, wherein the total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is 20% to 65% by weight based on the total weight of the ink.

6. The ink according to any one of claims 1 to 5, wherein the pigment dispersion is present in an amount of 1% to 40% by weight based on the total weight of the ink.

7. The ink according to any one of claims 1 to 6, wherein the pigment has a particle size (Dn50) of 0.020 μm to 0.150 μm as measured by disc centrifugation.

8. The ink according to any one of claims 1 to 7, wherein the pigment has a particle size distribution characterized by having: (a) Dv50 of 110 to 120 nm; and / or (b) Dv90 less than 350nm; Such as measurements via dynamic light scattering.

9. The ink according to any one of claims 1 to 8, wherein the poly(vinyl chloride-vinyl acetate) copolymer has: (a) Random copolymer structure, alternating copolymer structure, block copolymer structure, or graft copolymer structure; (b) A vinyl chloride:vinyl acetate monomer ratio of 80:20 to 90:10; and / or (c) 40000 g mol -1 Up to 50000 g mol -1 Mw.

10. The ink according to any one of claims 1 to 9, wherein the viscosity of the ink is 7 to 20 cP at 25°C.

11. The ink according to any one of claims 1 to 10, wherein the ink does not contain the following solvents: - It shows 1% or more evaporation at 30°C for 16 hours or at 150°C for 60 seconds; or - It is classified as flammable, corrosive or hazardous.

12. A process for preparing an ink as defined in any one of claims 1 to 11, comprising: (a) mixing the pigment dispersion as defined in any one of claims 1 to 7 with a first portion solvent composition comprising diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate to form a first mixture; and (b) The first mixture is mixed with a second portion solvent composition comprising soybean methyl ester and optionally diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate. This forms the ink as defined in any one of claims 1 to 11.

13. The process of claim 12, wherein step (a) comprises adding the pigment dispersion to a vortex of the first portion of the solvent composition in a dissolver with a tip velocity of 9 m / s or higher and mixing for 5 to 25 minutes.

14. The process according to claim 12 or 13, wherein step (b) comprises adding the second portion of the solvent composition to a vortex of the first mixture in a dissolver with a tip velocity of 1 to 8 m / s and mixing for 5 to 25 minutes.

15. Printing methods, including: - Provide inks as defined in any one of claims 1 to 11; and - The ink is printed onto the substrate using an inkjet printer.

16. A printed article comprising a substrate and ink as defined in any one of claims 1 to 11.

17. The printed article according to claim 16, wherein it is a textile, flooring or wallpaper.

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