Ink

Abstract

Disclosed is an ink comprising: (a) a solvent composition; and (b) a pigment dispersion; wherein the solvent composition comprises diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate wherein the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate is 50 wt% or more 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] The present invention relates to an ink, a process for producing an ink, a printing method and a printed article. BACKGROUND

[0002] Inkjet printing is used for a variety of printing applications and can provide high resolution images on a range of substrates. The increasing interest in safe and environmentally friendly technologies has led to an increased demand for inks using harmless components that pose a low or no risk to the environment. Furthermore, the use of volatile components, such as specific solvents, in inks is considered undesirable as substantial evaporation of these components or solvents can lead to drying of the ink in the print head, resulting in poor nozzle recovery. The viscosity of the ink can also easily change over time due to evaporation. Changes in viscosity over time will result in inks that are not suitable for inkjet printing. SUMMARY

[0003] TECHNICAL PROBLEM

[0004] It remains a particular problem to provide an ink that has advantages in terms of desired viscosity stability and evaporation properties, which exhibits good nozzle recovery in inkjet printing and which does not use volatile, hazardous or environmentally harmful solvents.

[0005] Therefore, there is a need for new inks that solve the above-mentioned problems.

[0006] SOLUTION TO THE PROBLEM

[0007] The present invention provides an ink comprising:

[0008] (a) a solvent composition; and

[0009] (b) a pigment dispersion;

[0010] wherein the solvent composition comprises diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate;

[0011] wherein the total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate is 50 wt.% or more based on the total weight of the ink;

[0012] and wherein the pigment dispersion comprises a pigment and a binder, the binder comprising a poly(vinyl chloride-co-vinyl acetate) copolymer.

[0013] The present invention further provides a process for producing an ink, comprising:

[0014] (a) mixing a pigment dispersion with a first part of a solvent composition comprising diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate to form a first mixture; and

[0015] (b) combining the first mixture with a second portion of a solvent composition, the second portion of the solvent composition comprising soy methyl ester and optionally comprising diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate,

[0016] to form an ink.

[0017] The present invention also provides a method of printing, comprising:

[0018] - providing an ink; and

[0019] - printing the ink onto a substrate using an inkjet printer.

[0020] The present invention also provides a printed article comprising a substrate and an ink.

[0021] The present inventors have surprisingly found that the inclusion of soy methyl ester in a solvent composition of an ink as described above, which further comprises a pigment dispersion as described above, results in an ink that provides the required viscosity stability and evaporation characteristics, and also exhibits good nozzle recovery in inkjet printing, and without the use of volatile, hazardous, or environmentally harmful solvents. DETAILED DESCRIPTION

[0022] Ink

[0023] The present invention provides an ink comprising:

[0024] (a) a solvent composition; and

[0025] (b) a pigment dispersion;

[0026] wherein the solvent composition comprises soy methyl ester, diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0027] The ink of the present invention comprises a solvent composition comprising diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0028] The ink of the present invention typically does not comprise a volatile, hazardous, or environmentally harmful solvent.

[0029] The ink of the present invention typically does not comprise a solvent classified as flammable, corrosive, or hazardous. The skilled person will understand which substances are classified as flammable, corrosive, or hazardous as part of their common general knowledge, and suitable solvent classifications include the Globally Harmonized System of Classification and Labelling of Chemicals (GHS); Fourth Revision, United Nations, New York and Geneva, 2011.

[0030] Preferably, the ink of the present application does not comprise one or more solvents selected from cyclohexanone, butyl glycol acetate and methoxy propanol acetate.

[0031] The ink of the present application typically has desirable evaporation properties. The ink of the present application typically does not comprise a solvent that shows 1 % or more evaporation by weight at 30°C over 16 hours, for example as determined by the following method:

[0032] - 2 g of test material is weighed into an open container (50 mm diameter);

[0033] - placed into an oven set to 30°C for a 16 hour period; and

[0034] - the weight loss is assessed at the end of the 16 hour period.

[0035] The ink of the present application typically does not comprise a solvent that shows 1 % or more evaporation by weight at 150°C, for example as determined by the following method:

[0036] - a moisture analyser (such as an Ohaus MB45) is used, with the temperature set to 150°C;

[0037] - 2 g of test material is weighed into a dish on the balance,

[0038] - the lid is closed.

[0039] - the test is terminated when the amount changes by 0.001 g within 60 seconds.

[0040] 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.

[0041] The solvent composition comprises diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate. The total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is 50% by weight or more based on the total weight of the ink. Typically, the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is 50% to 99% by weight based on the total weight of the ink, for example 50% to 97% by weight based on the total weight of the ink. More typically, the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is 61% by weight or more based on the total weight of the ink, for example 61% to 99% by weight based on the total weight of the ink, or 61% to 97% by weight 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 70% by weight or more based on the total weight of the ink, for example 70% to 99% by weight based on the total weight of the ink, or 70% to 97% by weight 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 79% by weight or more based on the total weight of the ink, for example 79% to 99% by weight based on the total weight of the ink, or 79% to 97% by weight 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 90% by weight or more based on the total weight of the ink, for example 90% to 99% by weight based on the total weight of the ink, or 90% to 97% by weight based on the total weight of the ink.

[0042] 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% by weight based on the total weight of the ink, diisobutyl glutarate is present in an amount of 10% by weight based on the total weight of the ink, and diisobutyl adipate is present in an amount of 12% by weight based on the total weight of the ink, then the total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate would be 30% by weight based on the total weight of the ink.

[0043] Diisobutyl succinate is typically present in an amount of 15% to 30% by weight 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% by weight 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% by weight based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0044] Preferably, diisobutyl succinate is present in an amount of 15% to 30% by weight, based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate; diisobutyl glutarate is present in an amount of 55% to 70% by weight, 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% by weight, based on the total weight of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0045] Diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate are available as commercially available solvent mixtures, such as Coasol (registered trademark) available from Chemoxy International Ltd and Saiper Chemicals Pvt Ltd.

[0046] The solvent composition may also contain soy methyl ester. Soy methyl ester is derived from an acid (hereinafter referred to as the acid component of soy methyl ester) and an alcohol (hereinafter referred to as the alcohol component of soy methyl ester).

[0047] The acid component of soybean methyl ester is an unsaturated fatty acid. Preferably, the acid component of soybean methyl ester is a diunsaturated fatty acid. Diunsaturated fatty acids can be obtained, for example, by hydrolysis of vegetable oils (e.g., soybean oil). Suitable examples of diunsaturated fatty acids include linoleic acid, eicosadienoic acid, and docosahexaenoic acid. Linoleic acid is preferably the acid component of the first ester. Linoleic acid can be obtained by hydrolysis of soybean oil.

[0048] The alcohol component of the first ester is a monohydric alcohol. Suitable examples of monohydric alcohols include methanol, ethanol, n-propanol, isopropanol, n-butanol, isobutanol, and tert-butanol. Methanol is the alcohol component of soybean methyl ester.

[0049] Soybean methyl esters can be esters of diunsaturated fatty acids and monohydric alcohols, and examples of soybean methyl esters include methyl esters such as methyl linoleate, methyl eicosadienoate, methyl dodecadienoate, and trans-linoleic acid. Methyl linoleate is preferred as a soybean methyl ester.

[0050] Typically, if present, soy methyl ester is present in an amount of 47% by weight or less based on the total weight of the ink, for example, from 1% to 47% by weight based on the total weight of the ink. Preferably, if present, soy methyl ester is present in an amount of 37% by weight or less based on the total weight of the ink, for example, from 1% to 37% by weight based on the total weight of the ink. More preferably, if present, soy methyl ester is present in an amount of 27% by weight or less based on the total weight of the ink, for example, from 1% to 27% by weight based on the total weight of the ink. Even more preferably, if present, soy methyl ester is present in an amount of 19% by weight or less based on the total weight of the ink, for example, from 1% to 19% by weight based on the total weight of the ink. Most preferably, soy methyl ester is not present in the ink of the present invention.

[0051] The solvent composition may further comprise esters, glycol esters, glycol ester acetates, glycol ethers, glycol ether acetates, lactones, adipates, succinates, glutarates, or mixtures thereof.

[0052] The ink of the present invention comprises a pigment dispersion. The pigment dispersion comprises a pigment and a binder. Unless otherwise stated, the term pigment dispersion as used herein typically refers to both pigment and binder. However, it should be understood that the pigment is typically present in the form of a dispersion throughout the ink.

[0053] The pigments used in the pigment dispersions of the inks of the present invention are not particularly limited. Typically, the pigment dispersions comprise red, blue, or black pigments, or mixtures thereof. The pigments may be magenta or cyan pigments. Preferably, the pigment dispersions comprise pigments selected from Pigment Red 202, Pigment Red 144, Pigment Red 166, Pigment Red 185, Pigment Red 254, Pigment Blue 15:3, Pigment Blue 60, and Pigment Black 7, or mixtures thereof. More preferably, the pigment dispersions comprise Pigment Red 202. Even more preferably, the pigment dispersions comprise Pigment Red 202 and a mixture of one or more additional pigments selected from Pigment Red 144, Pigment Red 166, Pigment Red 185, and Pigment Red 254.

[0054] Pigments typically have a number-average particle size (Dn50) of 0.020 μm to 0.150 μm, as measured by disc centrifugation, for example, using a CPS DC24000 disc centrifuge particle size analyzer.

[0055] Pigments typically have the following volume-average particle size, characterized by:

[0056] (a) Dv50 is 110 to 120 nm; and / or

[0057] (b) Dv90 is less than 350nm;

[0058] For example, measurements can be taken using dynamic light scattering, such as those using the Malvern Zetasizer Nano-ZS dynamic light scattering particle size analyzer.

[0059] The binder used in the pigment dispersion of the ink of the present invention is not particularly limited. The binder comprises a poly(vinyl chloride-vinyl acetate) copolymer. The poly(vinyl chloride-vinyl acetate) copolymer may have a random copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer may have an alternating copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer may have a block copolymer structure. The poly(vinyl chloride-vinyl acetate) copolymer may have a graft copolymer structure. The vinyl chloride:vinyl acetate monomer ratio of the poly(vinyl chloride-vinyl acetate) copolymer may be 80:20 to 90:10 (typically by weight:by weight). The poly(vinyl chloride-vinyl acetate) copolymer may have a content of 40,000 g mol. -1 Up to 50000 g mol -1 The molecular weight (Mw). The molecular weight (Mw) can be measured by methods well known to those skilled in the art, for example according to ISO 16014-3:2019.

[0060] The ratio of the binder (e.g., the poly(vinyl chloride-vinyl acetate) copolymer described above) to the pigment is typically 40:60 to 80:20 (typically wt:wt), such as 50:50 to 70:30 (typically wt:wt), 58:42 to 68:32 (typically wt:wt), 60:40 to 66:34 (typically wt:wt), or about 63:37 (typically wt:wt).

[0061] The pigment dispersion may be a commercially available pigment dispersion. Examples of commercially available pigment dispersions that can be used in the inks of this invention include the Microlith (registered trademark)-K series (e.g., Magenta 4330K, Magenta 4535K, Blue 7080K, Blue 6480 K and Black 0066K) available from BASF SE.

[0062] The pigment dispersion may be present in an amount of 1 to 20 wt% based on the total weight of the ink, for example, when the pigment dispersion contains a colored pigment. Preferably, the pigment dispersion is present in an amount of 1 to 10 wt% based on the total weight of the ink, for example, in an amount of 1 to 6%, 1 to 4 wt%, 2 to 6%, 3 to 5%, or about 4% based on the total weight of the ink. As mentioned above, the amount of the pigment dispersion is typically the total amount of pigment and binder.

[0063] The preferred inks of the present invention include those, wherein:

[0064] - The total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is from 50% to 97% by weight based on the total weight of the ink;

[0065] - Soy methyl esters are optionally present in the ink in an amount of 46% by weight or less based on the total weight of the ink;

[0066] - The pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0067] The preferred inks of the present invention include those, wherein:

[0068] - The total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is between 70% by weight and 97% by weight based on the total weight of the ink;

[0069] - Soy methyl esters are optionally present in the ink in an amount of 26% by weight or less based on the total weight of the ink;

[0070] - The pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0071] The particularly preferred inks of the present invention include those, wherein:

[0072] - The total amount of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate present in the ink is 95% to 97% by weight based on the total weight of the ink;

[0073] - Soy methyl esters are not present in inks; and

[0074] - The pigment dispersion is present in an amount of 3% to 5% by weight based on the total weight of the ink.

[0075] The inks of this invention typically have the viscosity required 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. The viscosity can be measured using a cone-plate viscometer, such as a Brookfield DV3T viscometer with a CPA-40Z cone operating at 10 rpm.

[0076] The ink of this invention exhibits excellent nozzle recovery. Typically, using a Ricoh Gen5 printhead (MH5420), after being idle at the spray temperature for at least 4 days, the ink shows no nozzle spray loss as determined by the following method.

[0077] The ink of this invention exhibits excellent wash resistance. Typically, as measured by the following method, after five washing cycles at 40°C, the color change of the ink is very small.

[0078] Ink preparation process

[0079] This invention provides a process for preparing the ink according to the invention, comprising:

[0080] (a) mixing a pigment dispersion with a first portion solvent composition comprising diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate to form a first mixture; and

[0081] (b) The first mixture is mixed with a second solvent composition comprising soybean methyl ester and optionally diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0082] This forms ink.

[0083] The components of the first part of the solvent composition may be added individually. The components of the first part of the solvent composition may be added simultaneously. The components of the first part of the solvent composition may be added sequentially.

[0084] The components of the second-part solvent composition may be added individually. The components of the second-part solvent composition may be added simultaneously. The components of the second-part solvent composition may be added sequentially.

[0085] Typically, step (a) of mixing the pigment dispersion with the first portion of the solvent composition includes adding the pigment dispersion to a vortex of the first portion of the solvent composition in a dissolver at a tip speed of 9 m / s or higher (e.g., 9 to 15 m / s, 10 to 12 m / s or about 10 m / s) and mixing for 5 to 25 minutes (e.g., 8 to 22 minutes, 10 to 20 minutes or about 15 minutes).

[0086] Typically, step (b) of mixing the first mixture with the second portion of the solvent composition includes 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 (e.g., 2 to 7 m / s or 3 to 6 m / s) and mixing for 5 to 15 minutes (e.g., 7 to 13 minutes, 9 to 11 minutes, or about 10 minutes). Preferably, step (b) includes adding the second portion of the solvent composition to a vortex of the first mixture in a dissolver with a tip velocity of 3 to 6 m / s and mixing for about 10 minutes.

[0087] Printing method

[0088] The general process of inkjet printing is well known to those skilled in the art. The inks of the present invention have been described herein, so those skilled in the art can readily apply the inks to suitable substrates in inkjet printing methods based on their common knowledge.

[0089] This invention also relates to a printing method. This invention provides a printing method comprising:

[0090] - Provides the ink of the present invention; and

[0091] - Use an inkjet printer to print ink onto a substrate.

[0092] There are no particular limitations on the substrate used in the printing method. The substrate can be formed from paper, nonwoven fabric, plastic, wood, metal, or a combination of these materials. Specific examples include natural paper, plastic film, synthetic paper, nonwoven fabric, wool, cloth, wood, semi-cured wallpaper (where the solid resin layer exists in a semi-gel form), fully cured wallpaper, metal sheets and metal films, or any combination of these materials. The substrate may include fleece backing paper. The substrate may be semi-rigid polyvinyl chloride suitable for flooring applications. The substrate may be polyethylene, suitable for packaging applications.

[0093] Multilayer substrates 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., aluminum).

[0094] Printed article

[0095] This invention also relates to printed articles. The invention provides a printed article comprising a substrate and the ink of this invention. The printed article of this invention can be a textile. The substrate in the printed article of this invention can be as described above with reference to the substrate in the printing method of this invention.

[0096] The printed articles of this invention can be flooring products. The printed articles of this invention can be wallpaper.

[0097] As described above, the printed articles of the present invention can be obtained by the printing method of the present invention.

[0098] The present invention will now be described through the following non-limiting embodiments.

[0099] Examples

[0100] Prepare inks with the compositions listed in Tables 1 and 2 (magenta ink), 3 (cyan ink), and 4 (black ink) according to the following procedures.

[0101] Stage 1 - The first portion of the solvent composition of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate is added to the disperser, and then at 9 m sec. -1The tip speed is used to stir to generate a vortex. The pigment dispersion is added to the first portion of the solvent composition and stirred for 10 to 20 minutes while maintaining a tip speed of 9 m / sec. -1 .

[0102] Phase 2 - Reduce tip velocity to 3 to 6 m / sec -1 A second-part solvent composition comprising diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate, and optionally soybean methyl ester, is added to the vortex of the composition of stage 1 and stirred for 10 minutes.

[0103] Analyze the viscosity stability of the ink and the nozzle recoverability.

[0104] The Brookfield DV3T cone-plate viscometer is suitable for determining the viscosity of inks. Viscosity is measured using the Brookfield DV3T viscometer with a CPA-40Z cone at 10 rpm. Viscosity can be measured at room temperature over a period of six months or one year, at 50°C over a period of two weeks, at 30°C over a period of six months or one year, and at 40°C over a period of six months.

[0105] If a viscosity change of less than 10% is recorded, the viscosity stability of the ink is classified as "A". If a viscosity change of 10% to 20% is recorded, the viscosity stability of the ink is classified as "A". If a viscosity change of 20% to 30% is recorded, the viscosity stability of the ink is classified as "A"; if a viscosity change of 30% to 50% is recorded, the viscosity stability of the ink is classified as "B"; and if a viscosity change of more than 50% is recorded, the viscosity stability of the ink is classified as "C".

[0106] Nozzle resilience was evaluated using a Ricoh Gen5 printhead (MH5420). Ink was delivered from a bottle with no reverse flow path. 9 pL droplets were used. The ejection frequency was 20 kHz. The ejection temperature was 30°C. The following process was used:

[0107] 1) Print the nozzle matrix test pattern on plain paper.

[0108] 2) Check that all nozzles (1280) are spraying.

[0109] 3) Stop spraying.

[0110] 4) Place the printhead at the spray temperature for 4 days.

[0111] 5) Restart spraying and print the nozzle matrix test pattern to check that all nozzles (1280) are spraying.

[0112] Do not clean, wipe, or cap the printhead during nozzle recovery testing.

[0113] Assess nozzle resilience and classify it as "A" “A” “A”, “B” or “C”.

[0114] The amounts of components shown in Tables 1 to 4 are weight percentages. The components used and the analytical results are as follows:

[0115] Pigment dispersions: Microlith (registered trademark) - K series (Microlith Magenta 4535 K, 63:37 weight: pigment dispersion in vinyl chloride / vinyl acetate adhesive, or Microlith Blue 7080 K, 50:50 weight: pigment dispersion in vinyl chloride / vinyl acetate adhesive, or Microlith Black 0066K, 48:52 weight: pigment dispersion in vinyl chloride / vinyl acetate adhesive).

[0116] Coasol (registered trademark): a mixture of diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate.

[0117] SME: Soybean Methyl Ester

[0118] [Table 1]

[0119]

[0120] [Table 2]

[0121]

[0122] [Table 3]

[0123]

[0124] [Table 4]

[0125]

[0126] As can be seen from the evaluations listed in the table above, the ink of the present invention exhibits excellent viscosity stability and excellent nozzle recoverability after short-term and long-term storage at temperatures including room temperature and elevated temperatures.

[0127] In addition, color changes due to washing were examined using ink (magenta ink 10 (Table 1)). Printing was performed using a Ricoh Gen5 printhead (MH5420). Ink was delivered in a bottle with no reverse flow. 10-20 pL droplets were used. The jetting frequency was 20 kHz. As substrates, cotton fabric (RTP clothing, 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).

[0128] As can be seen from the above evaluation, the ink of the present invention has excellent wash resistance.

[0129] According to color measurements, the color change of the ink due to washing was very small (DE2000<3).

[0130] The invention has been described above with reference to certain embodiments. However, these embodiments are merely illustrative, and those skilled in the art will understand that various modifications are possible without departing from the scope of the invention as defined in the appended claims, including combinations of features described above with reference to the individual embodiments (while their equivalents are also reasonably considered).

[0131] 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, filed on 28 September 2023, 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 diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate; The total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate is 50% by weight or more 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 magenta ink, cyan ink, or black ink.

3. The ink according to claim 1 or claim 2, wherein the pigment is Pigment Red 202, or a mixture comprising Pigment Red 202 and one or more other pigments, wherein the one or more other pigments are selected from Pigment Red 144, Pigment Red 166, Pigment Red 185, Pigment Red 254, Pigment Blue 15:3, Pigment Blue 60 and Pigment Black 7.

4. The ink according to any one of claims 1 to 3, wherein the total amount of diisobutyl succinate, diisobutyl glutarate and diisobutyl adipate present in the ink is 61% by weight or more based on the total weight of the ink, preferably 79% by weight or more based on the total weight of the ink, and more preferably 90% by weight or more based on the total weight of the ink.

5. The ink according to any one of claims 1 to 4, wherein the solvent composition further comprises soybean methyl ester.

6. The ink according to any one of claims 1 to 5, wherein the pigment dispersion is present in an amount of 1% to 20% 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 the following particle size distribution, characterized in that... have: (a) Dv50 at 110 to 120 nm; and / or (b) Dv90 less than 350 nm; as measured by 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 a solvent that: - 1% or more of evaporation is observed at 30°C for 16 hours or at 150°C for 60 seconds; or - 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 diisobutyl succinate, diisobutyl glutarate, and diisobutyl adipate, and optionally soybean methyl ester. 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 having a tip velocity of 1 to 8 m / s or higher, 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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