Compositions of inks based on coffee grounds and their preparation process

Abstract

The present invention relates to a method for preparing a pigment ink composition, comprising the following successive steps: a) Suspending raw coffee grounds in an aqueous solution comprising a dispersing agent, the mass ratio of the dispersing agent to the raw coffee grounds being greater than or equal to 10%, to obtain a suspension of dispersed coffee grounds; b) Grinding the suspension of dispersed coffee grounds at a temperature less than or equal to 40°C, to obtain a ground composition comprising coffee ground particles having a d95 value less than or equal to 10 µm. The invention also relates to a pigment ink composition comprising, in particular, by weight relative to the total weight of the composition: 4 to 25% coffee grounds with a d95 value less than or equal to 10 µm, at least 0.5%, preferably at least 0.8%, and a dispersing agent.

Description

Title of the invention: Coffee ground-based ink compositions and their preparation process. FIELD OF THE INVENTION

[0001] The present invention relates to coffee ground-based ink compositions, particularly intended for use as printing ink, and their preparation process. STATE OF THE ART

[0002] The inks used today in the printing sector, particularly for printing systems (for example flexography, screen printing or non-impact printers such as inkjet printers), or for artistic activities, contain many toxic compounds and / or compounds from non-renewable sources such as petrochemical compounds.

[0003] Two types of inks are distinguished: dye inks, and pigment inks.

[0004] Dye-based inks are composed of water-soluble dyes. Dyes can be of natural origin (derived from certain plants, for example) or synthetic (the majority). Dye-based inks have the advantage of diffusing very little light, resulting in saturated and vibrant colors, and are less expensive than pigment-based inks. However, dyes are sensitive to light, humidity, and ozone.

[0005] Pigment inks, on the other hand, contain pigments, which are solid, opaque particles suspended in a liquid. It is these pigments that give pigment inks their color. They are more expensive than dye-based inks, but are also more resistant to light, humidity, and gases (including ozone). However, on some glossy papers, they will not penetrate the substrate as deeply, which can affect color reproduction.

[0006] In black inks, the most commonly used pigment is carbon black, which is generally considered environmentally unfriendly because it comes from non-renewable sources, and its manufacturing process is very energy-intensive and / or produces a lot of waste or toxic byproducts. For example, the State of New York is considering banning the use of carbon black in black printing inks used for packaging and labels, with the aim of reducing packaging waste and improving recycling practices. Therefore, there is a need to develop new inks that do not contain such products.

[0007] Alternative inks based on pigments of plant origin, such as coffee grounds, have been described in the prior art. Coffee grounds are indeed a source of pigment of choice, as they are a common waste product, available in large quantities and easy to collect.

[0008] The prior art generally describes processes in which coffee grounds are ground, possibly in the presence of additives, or where applicable after a step of extracting residual soluble dyes, and then dried, with the ink formulation occurring only in a subsequent step. Examples of such processes are disclosed, for instance, in documents WO 2007 / 141557, WO 2008 / 047347 and US11517141.

[0009] However, prior art processes for preparing inks from coffee grounds do not allow for the complete valorization of the coffee grounds and still generate too much coffee waste. Indeed, the processes described in WO 2007 / 141557, WO 2008 / 047347 and US 11517141 generally use filtered fractions or the coffee beans themselves as starting material: these processes are therefore less environmentally friendly than a process using all the raw coffee grounds resulting from the consumption of coffee.

[0010] Thus, there is a need for processes for preparing a pigment ink composition based on coffee grounds, particularly for flexography, screen printing, or non-impact printing such as inkjet printing, which are easy to implement (particularly on an industrial scale), inexpensive, and which allow the entire coffee grounds to be used while ensuring good quality of the pigment ink obtained. Description of the invention

[0011] The invention aims to overcome these problems by implementing a process including a grinding step at a temperature less than or equal to 40°C of a composition comprising coffee grounds.

[0012] The average particle size of a pigment ink, whatever its field of application, must be low, generally less than or equal to 10 pm, to guarantee reproducibility, ease of use and aesthetics.

[0013] Furthermore, in a non-impact printer and in particular an inkjet printer, the ink is diffused using nozzles, which can become clogged if the pigments have a d95 value greater than 1 pm.

[0014] However, the applicant found that if the grinding took place at a temperature greater than or equal to 40°C, it was not possible to obtain such average particle sizes with good stability over time, due to the appearance of agglomeration or re-agglomeration phenomena of the coffee grounds particles. Without wanting to be bound by any theory, the degradation and / or gelation of polysaccharides naturally present in coffee grounds would generate these agglomeration / re-agglomeration phenomena which are detrimental to obtaining the desired average particle size, such degradation / gelation taking place at temperatures above approximately 40°C.

[0015] It should be noted that to maintain the grinding temperature at 40°C or less, the raw coffee grounds suspension must be cooled during grinding. Indeed, without cooling, the raw coffee grounds suspension heats up and reaches temperatures above 40°C, which leads to the agglomeration phenomena mentioned above.

[0016] In addition, unlike some inks used in the printing industry or for art, the pigment ink composition according to the invention requires very little, or even eliminates the need for, binders to ensure the formation of a continuous and uniform film, to improve the application of the ink on a substrate such as paper.

[0017] More generally, the ink of the invention preferably comprises only non-fossil components, and advantageously non-toxic ones.

[0018] In the process of the invention, the grinding step is carried out on a composition comprising the majority of the ink constituents. This yields a relatively viscous pigment ink composition (pigment paste), which can be used as is or diluted depending on the desired application. The process of the invention therefore offers great formulation flexibility.

[0019] Thus, according to a first aspect, the invention relates to a process for preparing a pigment ink composition, comprising the following successive steps: a) Suspension of raw coffee grounds in an aqueous solution comprising a dispersing agent, the mass ratio of the dispersing agent to the raw coffee grounds being greater than or equal to 10%, to obtain a suspension of dispersed coffee grounds;

[0020] b) Grinding the dispersed coffee grounds suspension, at a temperature less than or equal to 40°C, to obtain a ground composition comprising coffee grounds particles whose d95 value is less than or equal to 10 pm.

[0021] According to another aspect, the invention relates to a pigment ink composition comprising, by weight relative to the total weight of the composition: • 4 to 25% coffee grounds with a d95 value less than or equal to 10 pm, • at least 0.5%, preferably at least 0.8%, of a dispersing agent, • 0 to 15% humectant, • 0 to 10%, preferably 0.5 to 5%, of another pigment, • 0 to 1%, preferably 0.5 to 0.8%, of a preservative, • 0 to 2%, preferably 0.02 and 1%, of an anti-foaming agent, • a solvent comprising water, the solvent being in sufficient quantity to reach 100%.

[0022] According to another aspect, the invention relates to a use of the pigment ink composition of the invention as an ink for art, screen printing, flexography, and for indirect printing techniques, such as offset (an indirect printing technique where the ink is first transferred from a metal plate onto a cylinder (blanket), and then from the blanket onto the paper).

[0023] According to another aspect, the invention relates to a use of the pigment ink composition of the invention as ink for non-impact printers, in particular inkjet printers.

[0024] According to another aspect, the invention relates to an ink cartridge, in particular for a non-impact printer such as an inkjet printer, the cartridge comprising the pigment ink composition of the invention, and more particularly a composition for which the d95 value of the coffee grounds is less than or equal to 1 pm, preferably less than or equal to 0.5 pm. DETAILED DESCRIPTION OF THE INVENTION 1. Process

[0025] The invention relates to a method for preparing a pigment ink composition, comprising the following successive steps: a) Suspending raw coffee grounds in an aqueous solution comprising a dispersing agent, the mass ratio of the dispersing agent to the raw coffee grounds being greater than or equal to 10%, to obtain a dispersed coffee grounds suspension;

[0026] b) Grinding the dispersed coffee grounds suspension at a lower temperature or equal to 40°C, to obtain a ground composition comprising coffee grounds particles with a d95 value less than or equal to 10 pm.

[0027] As understood here, the term "average particle size" means the average size of the grains of a powder (in particular of solid pigments and coffee grounds), by volume.

[0028] The particle size distribution of powders (in particular of solid pigments and coffee grounds) is generally characterized by the values ​​of d-, d-, d- and / or d-. The dx, where X represents for example 10 or 50 or 90 or 95, is the Xth percentile of the particle size distribution, by volume; that is to say that X% of the particles have a size less than or equal to dx and (100-X)% of the particles have a size greater than dx.

[0029] The average particle size can be measured using grinding gauges and / or light diffraction techniques. The particle size distribution (values ​​of d10, d50, d90 and / or d95) is generally measured using light diffraction techniques.

[0030] Light diffusion equipment is well known in the art. For example, a laser particle size analyzer, such as a Malvern MasterSizer 3000 or Beckman Coulter LS 13320 laser particle size analyzer, can be used. Since the particles are dark in color, it is preferable to set the light shading to a value between 20% and 30%, in particular approximately 25%.

[0031] Grind gauges allow the fineness of a dispersion, such as an ink with a solid pigment, to be determined. The technique generally used is that of grind fineness gauges, also called the Hegman gauge or North gauge technique. A fineness gauge is a flat steel block whose surface is scored with flat, uniform grooves extending along the entire length of the block, from a maximum depth at one end of the gauge and decreasing until reaching the zero point at the other edge of the steel block. The depth of the grooves can be read using the scales engraved on the sides. According to this technique, the ink containing the ground pigment is deposited onto a grind fineness gauge and then spread using a scraper along the groove of the gauge. During spreading, the coarser particles are identified as the groove becomes deeper.The fineness of dispersion is read on the graduated scale at the point where aggregates or particles first appear as streaks or scratches.

[0032] The expression "particles with a particle size less than X" refers to particles whose total diameter (or maximum size) is less than X. Similarly, the expression "particles with a particle size greater than Y" refers to particles whose total diameter (or maximum size) is greater than Y.

[0033] The lower (or upper) particle size of a powder (in particular coffee grounds) is generally determined by sieving, using sieves with mesh sizes equal to X (or Y), the target lower particle size value. Step a)

[0034] The term "raw coffee grounds" herein means coffee grounds directly collected after percolation and / or extraction with water. Raw coffee grounds as defined herein have not been subjected to any processing step consisting of filtration and / or extraction with a solvent other than water, such as alcohol. Raw coffee grounds used in the invention are generally considered food waste.

[0035] Advantageously, the raw coffee grounds are subjected to a preliminary drying step (a0) to obtain dried raw coffee grounds, which are then used in the process of the invention. Those skilled in the art will know how to choose suitable drying conditions to sufficiently reduce the moisture content of the coffee grounds without altering them. In particular, the raw coffee grounds may be placed in a heated oven, notably at a temperature of 50°C to 80°C, preferably 55°C to 75°C, for a typical duration of 1 to 48 hours, particularly 6 to 24 hours.

[0036] Optionally, a step a1) of sieving the raw and possibly dried coffee grounds is carried out before step a) to obtain sieved coffee grounds with a particle size less than or equal to 600 pm, preferably less than or equal to 500 pm.

[0037] In this embodiment comprising a sieving step (a), the particle size of the sieved coffee grounds is typically greater than or equal to 200 µm, in particular greater than or equal to 300 µm, for example greater than or equal to 400 µm. This sieving step also provides a coarse fraction (the fraction retained by the sieve), i.e., a fraction with a particle size greater than 500 µm or 600 µm. In this embodiment, the coarse fraction is subjected to a grinding step to obtain coffee grounds with a particle size less than or equal to 600 µm, preferably less than or equal to 500 µm. Thus, even when a sieving step is implemented, all of the coffee grounds are advantageously used in the process.

[0038] The dispersing agent serves to stabilize the aqueous suspension of coffee grounds, notably by preventing agglomeration / re-agglomeration. The dispersing agent thus improves the stability of the pigment ink composition obtained in the process.

[0039] The dispersing agent is preferably non-fossil and advantageously non-toxic. In particular, it may be compatible with food contact and is preferably derived from renewable sources. It is advantageously suited for use as an ink additive. It may also advantageously exhibit humectant properties.

[0040] Examples of dispersing agents include polymeric dispersing agents, such as copolymer dispersing agents, i.e., those resulting from the polymerization of several monomers, in particular styrenic and / or acrylic and / or maleic acid. Dispersing agents are thus preferably polymers, particularly copolymers, of high molecular weight. The dispersing agent is advantageously nonionic or anionic, preferably nonionic. The range of dispersing agents usable in the process of the invention may be cited in particular as an example. EDAPLAN® marketed by Münzig Chemie, or the DISPERBYK® range (notably the DISPERBYK-2012) marketed by BYK.

[0041] The mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) is greater than or equal to 10%, preferably greater than or equal to 15%, in particular greater than or equal to 20%.

[0042] In addition, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) is typically less than or equal to 100%.

[0043] Preferably, especially when the ink is intended for use for art, and for non-impact printing techniques, such as inkjet printing, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) varies from 15% to 50%, in particular from 20% to 35% or from 20% to 30%.

[0044] According to one variant, particularly when the ink is intended for use in flexography, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) varies from 50% to 100%.

[0045] Advantageously, particularly when the ink is intended for use for art, and for non-impact printing techniques, such as inkjet printing, the composition may contain from 0 to 5% by weight relative to the total weight of the composition of a solvent (other than water) such as an alcohol, in particular isopropyl alcohol (IPA), which contributes in particular to improving the drying of the ink.

[0046] Advantageously, particularly when the ink is intended for use for art, and for non-impact printing techniques, such as inkjet printing, the composition may contain 0 to 1% by weight relative to the total weight of the composition of a buffering agent to control the pH.

[0047] Preferably, the aqueous solution of step a) further comprises a preservative and / or another pigment. The preservative and the other pigment are preferably non-fossil and advantageously non-toxic. In particular, they may be compatible with food use and are preferably derived from renewable sources.

[0048] The preservative's function is to slow down or prevent the degradation, particularly biological degradation, of the formulation (mold, etc.). Advantageously, the preservative comprises or is composed of sorbic acid or a salt thereof, in particular sodium sorbate or potassium sorbate.

[0049] The other pigment is preferably a black pigment, preferably non-fossil, such as vegetable charcoal. It may, in particular, be the food pigment El53, or charcoal derived from wood waste. The function of the other pigment is to enhance the color intensity of the pigment ink composition.

[0050] Typically, the aqueous solution of step a) further comprises an antifoaming agent and / or a humectant.

[0051] The humectant (also called a "wetting agent") serves to prevent the pigment ink composition from drying out too quickly in an inkjet printer cartridge in which it may be stored. Like the other components, the humectant is preferably non-fossil-based and advantageously non-toxic. In particular, it may be compatible with food contact and is preferably derived from renewable sources. Typically, the humectant comprises or is composed of glycerin.

[0052] Antifoaming agents are well known to those skilled in the art. An antifoaming agent suitable for pigment ink formulations, preferably non-fossil, and advantageously non-toxic, should preferably be chosen. Examples of antifoaming agents usable in the process of the invention are the AGIT AN® antifoaming agents marketed by Münzig Chemie or the BYK® antifoaming agents such as BYK®94, marketed by BYK.

[0053] The ink composition may further comprise a resin, particularly when the ink composition is useful for flexography. The resin may be natural or synthetic. Examples of synthetic resins are acrylic resins. Examples of natural resins are gums, and in particular shellac. Preferably, a natural resin, and in particular shellac, will be chosen. Step b)

[0054] Step b) of grinding makes it possible to obtain ground composition comprising coffee grounds particles whose value of d95 is less than or equal to 10 pm.

[0055] The d95 is the 95th percentile of the particle size distribution, by volume, that is to say that 95% (by volume) of the particles have a size less than or equal to d95 and 5% (by volume) of the particles have a size greater than d95.

[0056] Typically, step b) of grinding is implemented by a ball mill or an attrition machine, advantageously comprising a temperature control system adapted to maintain the temperature of the raw coffee grounds suspension at a value less than or equal to 40°C, in particular less than or equal to 36°C, preferably less than or equal to 30°C, in particular less than or equal to 27°C, during grinding.

[0057] In some embodiments, the ball mill or an attrition mill includes a grinding chamber, the temperature in the grinding chamber being controlled to be less than or equal to 40°C, in particular less than or equal to 36°C, preferably less than or equal to 30°C, in particular less than or equal to 27°C.

[0058] Typically the temperature in the grinding chamber is from 1°C to 40°C, in particular from 1°C to 36°C, in particular from 10°C to 36°C, preferably from 15°C or 20°C to 36°C.

[0059] The grinding step is generally continued either for a predetermined duration or until a value of a measurement using a fineness gauge or a value of d95 is less than or equal to a predetermined value. Specific embodiments

[0060] The value of d95 of the ground composition is in particular less than or equal to 1 pm, preferably less than or equal to 0.5 pm.

[0061] The size of the beads, the grinding speed, and / or the specific energy input can be adjusted during step b) to obtain a composition comprising particles with a d95 value less than or equal to 1 µm. Preferably, in this embodiment, the mass ratio of the dispersing agent to the raw coffee grounds (optionally dried and / or sieved) is greater than or equal to 15%, and preferably greater than or equal to 20%. Furthermore, the mass ratio of the dispersing agent to the raw coffee grounds (optionally dried and / or sieved) is typically less than or equal to 50%, in particular less than or equal to 35%. Preferably, the mass ratio of the dispersing agent to the raw coffee grounds (optionally dried and / or sieved) ranges from 20% to 30%. Step c) optional

[0062] The process may further include a step c) of diluting the ground composition obtained in step b) by adding an aqueous composition comprising a solvent and optionally one or more additives chosen from a humectant and an antifoaming agent.

[0063] According to certain variations, the aqueous composition may also include a resin, particularly when the composition is useful for flexography. Alternatively, the resin may be added to the ground composition obtained in step b), or to the mixture thereof with the aqueous composition.

[0064] The resin can be natural or synthetic. The resin, whether natural or synthetic, may be as described in step a). Preferably, a natural resin will be chosen, and in particular shellac.

[0065] In some embodiments, the process comprises:

[0066] aO) Drying of raw coffee grounds to obtain dried raw coffee grounds,

[0067] a) Suspension of dried raw coffee grounds in an aqueous solution including a dispersing agent, the mass ratio of the dispersing agent to the dried raw coffee grounds being greater than or equal to 10%, to obtain a suspension of dispersed coffee grounds;

[0068] b) Grinding the dispersed coffee grounds suspension, at a temperature less than or equal to 40°C, to obtain a ground composition comprising coffee grounds particles whose d95 value is less than or equal to 10 pm.

[0069] In some embodiments, the process comprises:

[0070] al) Sieving raw coffee grounds to obtain sieved coffee grounds with a particle size of less than or equal to 600 µm, preferably less than or equal to 500 µm,

[0071] a) Suspension of sieved coffee grounds in an aqueous solution comprising a dispersing agent, the mass ratio of the dispersing agent to the sieved coffee grounds being greater than or equal to 10%, to obtain a suspension of dispersed coffee grounds;

[0072] b) Grinding the dispersed coffee grounds suspension, at a temperature less than or equal to 40°C, to obtain a ground composition comprising coffee grounds particles whose d95 value is less than or equal to 10 pm.

[0073] In some embodiments, the process comprises:

[0074] aO) Drying of raw coffee grounds to obtain dried raw coffee grounds,

[0075] al) Sieving of the dried raw coffee grounds to obtain sieved coffee grounds particle size less than or equal to 600 µm, preferably less than or equal to 500 µm,

[0076] a) Suspension of sieved coffee grounds in an aqueous solution comprising a dispersing agent, the mass ratio of the dispersing agent to the sieved coffee grounds being greater than or equal to 10%, to obtain a suspension of dispersed coffee grounds;

[0077] b) Grinding the dispersed coffee grounds suspension, at a temperature less than or equal to 40°C, to obtain a ground composition comprising coffee grounds particles whose d95 value is less than or equal to 10 pm.

[0078] In embodiments comprising a step a1), this step a1) advantageously comprises grinding the fraction with a particle size greater than 500 pm or 600 pm (coarse fraction) to a particle size less than or equal to 600 pm, preferably less than or equal to 500 pm to give a coarse ground fraction and adding this coarse ground fraction to the sieved coffee grounds. 2. Composition of pigment ink

[0079] The invention also relates to a pigment ink composition comprising, by weight relative to the total weight of the composition: • 4 to 25% coffee grounds with a d95 value less than or equal to 10 pm, • at least 0.5% dispersing agent, • 0 to 15% humectant, • 0 to 10%, preferably 0.5 to 5%, of another pigment, • 0 to 1%, preferably 0.5 to 0.8%, of a preservative, • 0 to 2%, preferably 0.02 and 1%, of an anti-foaming agent, • a solvent comprising water, the solvent being in sufficient quantity to reach 100%.

[0080] The ink composition may further comprise a resin, particularly when the ink composition is useful for flexography. The resin may be natural or synthetic.

[0081] Examples of synthetic resins are acrylic resins. Examples of natural resins are gums, and in particular shellac. Preferably, a natural resin should be chosen, and in particular shellac.

[0082] The pigment ink composition can be obtained by the process of the invention.

[0083] Any solid compound dispersed in the composition will advantageously have a d95 value less than or equal to 10 pm. Generally, only the other pigment is insoluble at the ink's operating temperature (particularly between 15°C and 30°C), and in solid form (i.e., dispersed) in the composition.

[0084] The composition may include from 4 to 20%, by weight, of coffee grounds with a d95 value less than or equal to 10 pm, relative to the total weight of the composition.

[0085] The composition may include at least 0.8%, in particular at least 1% by weight of dispersing agent, relative to the total weight of the composition.

[0086] The solvent comprises or preferably consists of water.

[0087] According to some embodiments, the composition of pigment ink is devoid of sulfur, particularly elemental sulfur.

[0088] The invention makes it possible to significantly reduce, or even eliminate, the use of a binder. Thus, the pigment ink composition is advantageously free of binders, in particular alginate gum.

[0089] As previously stated, the dispersing agent, the humectant, the preservative, the other pigment, and the antifoaming agent are preferably non-fossil and advantageously non-toxic. In particular, they may be compatible with food contact and are preferably derived from renewable sources. Preferably, they are suitable for use as ink additives.

[0090] The dispersing agent, the humectant, the preservative, the other pigment and the antifoaming agent may be as defined above for the process.

[0091] Examples of dispersing agents are polymeric dispersing agents, such as copolymer dispersing agents, i.e., those resulting from the polymerization of several monomers, in particular styrenic and / or acrylic and / or maleic acid. Dispersing agents are thus preferably polymers, in particular of High molecular weight copolymers. The dispersing agent is advantageously non-ionic or anionic, preferably non-ionic. Examples of dispersing agents usable in the process of the invention include the EDAPLAN® range marketed by Münzig Chemie, or the DISPERBYK® range (in particular DISPERBYK-2012) marketed by BYK.

[0092] The mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) is greater than or equal to 10%, preferably greater than or equal to 15%, in particular greater than or equal to 20%.

[0093] In addition, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) is typically less than or equal to 100%, in particular less than or equal to 50%, in particular less than or equal to 35%.

[0094] Preferably:

[0095] - the humectant comprises or is made up of glycerin, and / or

[0096] - the preservative comprises or is made up of sorbic acid or a salt thereof ci, in particular sodium sorbate or potassium sorbate.

[0097] The other pigment is preferably a black pigment, such as vegetable charcoal. It may, in particular, be the food pigment El53. The other pigment advantageously has a d95 value less than or equal to 10 pm. Preferably, the sum of the black pigment and coffee grounds content is less than or equal to 25%.

[0098] Advantageously, particularly when the ink is intended for use for art, and for non-impact printing techniques, such as inkjet printing, the composition may contain from 0 to 5% by weight relative to the total weight of the composition of a solvent (other than water) such as an alcohol, in particular isopropyl alcohol (IPA), which contributes in particular to improving the drying of the ink.

[0099] Advantageously, particularly when the ink is intended for use for art, and for non-impact printing techniques, such as inkjet printing, the composition may contain 0 to 1% by weight relative to the total weight of the composition of a buffering agent to control the pH.

[0100] According to some variants, the dispersing agent has humectant properties: it then acts as a humectant. In these variants, preferably, the composition does not include any other humectant, i.e., it includes 0% by weight of any humectant other than the dispersing agent. Ready-to-use ink

[0101] According to certain variants, particularly when the ink is intended for use for art and for non-impact printing techniques, such as inkjet printing, the pigment ink composition is ready to use, i.e. it can be used directly without prior dilution.

[0102] According to these variants, particularly when the ink is intended for use for art, and for non-impact printing techniques, such as inkjet printing, the "ready-to-use" pigment ink composition advantageously comprises 4 to 5% by weight of coffee grounds with a d95 value less than or equal to 10 pm, relative to the total weight of the composition.

[0103] Advantageously, the "ready-to-use" pigment ink composition preferably comprises 0 to 0.07%, preferably 0.02 and 0.07%, of an anti-foaming agent, by weight relative to the total weight of the composition.

[0104] Typically, the "ready-to-use" pigment ink composition comprises at most 2%, or at most 1.5% by weight of dispersing agent, relative to the total weight of the composition.

[0105] Preferably, especially when the ink is intended for use for art, and for non-impact printing techniques, such as inkjet printing, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) varies from 15% to 50%, in particular from 20% to 35% or from 20% to 30%.

[0106] The “ready-to-use” pigment ink composition may include 0 to 1%, preferably 0.5 to 0.8%, of another pigment, advantageously a black pigment, in particular as defined above.

[0107] Advantageously, particularly when the ink is intended for use in art and for non-impact printing techniques such as inkjet printing, the "ready-to-use" pigment ink composition is resin-free. It is also advantageously binder-free.

[0108] According to certain embodiments, particularly when the pigment ink composition is intended for use in printing (especially non-impact printing, preferably inkjet), the d95 value of the coffee grounds is less than or equal to 1 pm, preferably less than or equal to 0.5 pm. In these embodiments, preferably the other solid components (i.e., insoluble at the ink's operating temperature, particularly between 15°C and 30°C) of the composition, particularly the other pigment, have a d95 value of the coffee grounds less than or equal to 1 pm, preferably less than or equal to 0.5 pm.

[0109] Advantageously, the "ready-to-use" pigment ink composition has a viscosity of 3 to 20 mPa.s (1000 s⁴). The viscosity is measured, for example, using a rheometer, such as an MCR302 rheometer marketed by Anton Paar, at 25°C, for 285 to 286 s, with a shear rate ranging from 0.1 to 1000 s⁻¹.

[0110] Finally, the pigment ink composition preferably has a density of 1,000 to 1,500 kg.m3. Concentrated ink

[0111] According to certain variants, particularly when the ink is intended for use in flexography, the pigment ink composition may be in concentrated form, i.e. it must be diluted before use.

[0112] The concentrated pigment composition typically comprises 5 to 20% by weight of coffee grounds with a d95 value less than or equal to 10 pm, relative to the total weight of the composition.

[0113] According to certain variants, particularly when the ink is intended for use in flexography, the composition advantageously comprises at least 2%, in particular at least 5% by weight of dispersing agent, and typically at most 25%, or at most 20% by weight of dispersing agent, relative to the total weight of the composition.

[0114] According to certain variants, particularly when the ink is intended for use in flexography, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) advantageously varies from 50% to 100%.

[0115] According to some embodiments, particularly when the ink is intended for use in flexography, the concentrated composition further comprises a resin, in particular as defined for step a) above. According to other embodiments, the concentrated composition is resin-free.

[0116] According to these variants, the “concentrated” pigment ink composition preferably includes 0.5 to 1% of an anti-foaming agent, by weight relative to the total weight of the composition.

[0117] Preferably, the sum of the black pigment and coffee grounds content is less than or equal to 25%. 3. Uses

[0118] The invention also relates to a use of the pigment ink composition of the invention as an ink for art, in particular for drawing, painting or calligraphy.

[0119] The pigment ink composition of the invention can also be used as ink for screen printing, flexography, and for indirect printing techniques, such as offset printing.

[0120] The pigment ink composition of the invention can also be used, in particular when the d95 value of the coffee grounds is less than or equal to 1 pm, preferably less than or equal to 0.5 pm, as ink for non-impact printers, in particular inkjet printers.

[0121] The pigment ink composition of the invention can be used on various substrates, such as paper, textiles, cardboard, or plastic film (in particular intended for packaging).

[0122] The invention also relates to an ink cartridge, particularly for a non-impact printer such as an inkjet printer, the cartridge comprising the pigment ink composition, particularly when the d95 value of the coffee grounds is less than or equal to 1 µm, preferably less than or equal to 0.5 µm. EXAMPLES

[0123] The following examples are given by way of illustration, but shall in no way be considered as limiting the present invention. Materials and Methods

[0124] The ingredients in Table 1 below have been used in the examples of the present invention.

[0125] [Tables 1] Ingredients Product Supplier Dispersant 1 Solsperse 46000 Lubrizol Dispersant 2 EDAPLAN® 918 Münzig Chemie Dispersant 3 JH3 / 163 / 2 Münzig Chemie Dispersant 4 DISPERBYK-2012 BYK Preservative Potassium Sorbate Cuisineaddict Black Pigment 1 E153 Cuisineaddict Black Pigment 2 Bioblack Nature Coatings Inc. Antifoaming Agent 1 AGIT AN® 761 Münzig Chemie Antifoaming Agent 2 BYK-094 BYK Wetting Agent Glycerin (or Glycerol) Isolatech Methods for measuring particle size

[0126] Particle size analyses are performed using a Mastersizer 3000 laser diffraction particle size analyzer (Malvem Panalytical), with a light shading percentage of 25%. Rheological tests

[0127] Rheology measurements are carried out with a rheometer, such as an MCR302 rheometer marketed by Anton Paar, with a Plate-Plate type geometry (50 mm), a measurement slit of 0.5 mm, at 25°C, for 285 to 286 s, and a shear rate ranging from 0.1 to 1000 s*. Example 1 - preparation of raw coffee grounds

[0128] Raw coffee grounds are placed in an oven at 65°C for 16 to 24 hours.

[0129] The dried raw coffee grounds are then sieved with a 500 µm mesh stainless steel sieve. Approximately 5% by volume of the coffee grounds constitutes the coarse fraction removed.

[0130] The dried and sieved raw coffee grounds thus obtained are used directly in ink formulations, or stored in a plastic or glass container for later use

[0131] Example 2 - Influence of temperature during grinding

[0132] Composition 1 shown in Table 2 below was used to carry out the grinding tests of Example 2.

[0133] [Tables2] Constituents Composition 1 (in g) Water 80.72 Dispersant 1 0.78 Coffee grounds 6.50 Preservative 1 Black pigment 1 1 Antifoaming agent 1 0 Wetting agent 10 Dispersant / coffee grounds ratio 0.12

[0134] The grinding step was carried out in an Emax grinder (marketed by RETSCH). The grinding was carried out with zirconium (ZrO) beads, with a diameter of 0.5 mm.

[0135] The grinding speed is set at 1200 rpm.

[0136] The chamber is equipped with a cooling device.

[0137] When the temperature control device is set to a temperature of 50°C, the result obtained, regardless of the grinding time, is a pasty residue: re-agglomeration phenomena are observed. The average particle size of the resulting composition is observed to be greater than 10 pm, or even 30 pm.

[0138] When the temperature control device is set to a temperature of 36°C, the final composition obtained is fluid. Adjusting the grinding time and the pellet size then makes it possible to obtain a d95 value less than or equal to 10 pm.

[0139] Example 3 - Implementation of the process of the invention

[0140] Compositions 2 and 3 shown in Table 3 below were used to carry out the grinding tests of Example 3.

[0141] [Tables3] Constituents Composition 2 (in g) Composition 3 (in g) Composition 4 (in g) Water 592.24 592.24 592.24 Dispersant 2 4.7 0 0 Dispersant 3 0 4.7 7.1 Coffee grounds 31.31 31.31 31.31 Preservative 4.82 4.82 4.82 Black pigment 1 4.82 4.82 4.82 Antifoaming agent 1 0.32 0.32 0.32 Wetting agent 63.79 63.79 63.79 Dispersant / coffee grounds ratio 0.15 0.15 0.23

[0142] The d95 of the raw coffee grounds used in compositions 2 and 3 is approximately 598 pm.

[0143] The grinding step was carried out in a LabStar mill (marketed by NETZSCH Feinmahltechnik). The grinding was carried out with zirconium (ZrO) beads of varying diameters.

[0144] The grinding chamber is equipped with a cooling device, set so that the internal temperature does not exceed 30°C.

[0145] The values ​​of d10, d50 and d90 shown in Table 4 below were obtained with compositions 2 and 3:

[0146] [Tables4] Test Composition Tested Diameter of Balls Grinding Speed ​​(rpm) Grinding Time (min) d10 (pm) d50 (pm) d95 (pm) 1 Composition 2 1.0-1.2 mm 2750 90 0.71 6.97 35.3 2 Composition 3 1.4-1.6 mm 2750 207 0.08 0.60 5.88 3 Composition 4 1.4-1.6 mm 3000 264 0.07 0.52 1.03 4 Composition 4 1.0-1.2 mm 3500 86 0.02 0.07 13.3 5 Composition 4 1.0-1.2 mm 3500 188 0.03 0.09 0.22

[0147] It can be seen that by adjusting the size of the balls, the speed and the duration of the grinding, it is possible to obtain a composition comprising particles whose value of d95 is less than or equal to 10 pm and to go down to a value of d95 less than 1 pm. Example 4 - Application for art

[0148] The ink composition of test 5 has been tested in applications for art, including drawing and calligraphy.

[0149] The results obtained are quite similar to those of a commercial ink using petroleum-based pigments, both in terms of aesthetic rendering and ease of use.

[0150] Example 5 - Printing tests with an inkjet printer

[0151] The ink composition to be tested, possibly diluted in water, is injected into an ink cartridge for an inkjet printer (for example, HEMEI brand) using a syringe.

[0152] The cartridge thus filled is used in an Epson WORKFORCE WF-2010W inkjet printer (home printer) or industrial (pilot scale machine).

[0153] A test print of a text is then carried out on a sheet of white office paper, and another test is carried out on photo paper. Example 6 - Flexography Tests

[0154] [Tables5] Constituents Composition 5 (in g) Composition 5 (in % by weight) Water 477 79.5 Dispersant 4 39 6.5 Coffee grounds 78 13.0 Antifoaming agent 2 6 1.0 Dispersant / coffee grounds ratio 0.5 0.5

[0155] Composition 5 is ground in an attrition unit, the grinding chamber of which is equipped with a rotary disc mixer. The grinding chamber is also equipped with a cooling device, set so that the internal temperature does not exceed 40°C.

[0156] Particles are obtained whose d95 value is less than or equal to 10 pm, or even less than or equal to 1 pm, in particular depending on the duration of the grinding.

[0157] An acrylic resin (Joncryl® 2640 resin marketed by BASF) or shellac is then added to the ground ink composition, and optionally an aqueous suspension of black pigment 2 to intensify the color of the ink if necessary.

[0158] This composition comprising the resin is then used to produce flexographic prints on a Flexiproof brand machine, on paper support, label and flexible packaging.

[0159] The general appearance of the printed materials thus obtained, their colorimetry, as well as their gloss and their solidity or resistance to light, are studied.

Claims

1. Demands Method for preparing a pigment ink composition, the pigment ink composition comprising, by weight relative to the total weight of the composition: • 4 to 25% coffee grounds with a d95 value less than or equal to 10 pm, • at least 0.5%, preferably at least 0.8%, of a dispersing agent, • 0 to 15% humectant, • 0 to 10%, preferably 0.5 to 5%, of another pigment, • 0 to 1%, preferably 0.5 to 0.8%, of a preservative, • 0 to 2%, preferably 0.02 and 1%, of an antifoaming agent, • a solvent containing water, the solvent being in sufficient quantity to reach 100%, The process includes the following successive steps: a) Suspension of raw coffee grounds in an aqueous solution comprising a dispersing agent, the mass ratio of the dispersing agent to the raw coffee grounds being greater than or equal to 10%, to obtain a suspension of dispersed coffee grounds; b) Grinding of the dispersed coffee grounds suspension, at a temperature less than or equal to 40°C, to obtain a ground composition comprising coffee grounds particles having a d95 value less than or equal to 10 pm.

2. A method according to claim 1, characterized in that step b) of grinding is carried out by a ball mill or an attrition machine.

3. A process according to claim 1 or 2, characterized in that the mass ratio of the dispersing agent to the raw coffee grounds in step a) is greater than or equal to 20%, and less than or equal to 100%.

4. A process according to any one of claims 1 to 3, characterized in that the aqueous solution of step a) further comprises a preservative and / or another pigment.

5. A process according to any one of claims 1 to 4, characterized in that the aqueous solution of step a) further comprises an antifoaming agent and / or a humectant agent.

6. A process according to any one of claims 1 to 5, characterized in that it further comprises a step c) of diluting the ground composition obtained in step b) by adding an aqueous composition comprising a solvent and optionally one or more additives selected from a humectant and an antifoaming agent.

7. A process according to any one of claims 1 to 6, characterized in that the value of d95 of the ground composition is less than or equal to 1 pm, preferably less than or equal to 0.5 pm.

8. Composition of pigment ink comprising, by weight relative to the total weight of the composition: • 4 to 25% coffee grounds with a d95 value less than or equal to 10 pm, • at least 0.5%, preferably at least 0.8%, of a dispersing agent, • 0 to 15% humectant, • 0 to 10%, preferably 0.5 to 5%, of another pigment, • 0 to 1%, preferably 0.5 to 0.8%, of a preservative, • 0 to 2%, preferably 0.02 and 1%, of an antifoaming agent, • a solvent comprising water, the solvent being in sufficient quantity to reach 100%.

9. Pigment ink composition according to claim 8, characterized in that it is obtained by the process according to any one of claims 1 to 7.

10. Pigment ink composition according to claim 8 or 9, characterized in that: - the humectant includes glycerin, and / or - the preservative includes sorbic acid or a salt thereof, in particular sodium sorbate or potassium sorbate.

11. Pigment ink composition according to any one of claims 8 to 10, characterized in that the pigment is a black pigment such as vegetable charcoal.

12. Pigment ink composition according to any one of claims 8 to 11, characterized in that the d95 value of the coffee grounds is less than or equal to 1 pm, preferably less than or equal to 0.5 pm.

13. Pigment ink composition according to any one of claims 8 to 12, characterized in that it further comprises a resin.

14. Use of the pigment ink composition according to any one of claims 8 to 13 as ink for art, screen printing, flexography, and for indirect printing techniques, such as offset printing.

15. Use of the pigment ink composition of claim 12, as ink for non-impact printers, in particular inkjet printers.

16. Ink cartridge, in particular for non-impact printers such as inkjet printers, the cartridge comprising the pigment ink composition of claim 12.