Ink compositions based on coffee grounds and method for preparing same

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 dispersant, the weight ratio of the dispersant to the raw coffee grounds being greater than or equal to 10%, to obtain a suspension of dispersed coffee grounds; b) milling the suspension of dispersed coffee grounds, at a temperature below or equal to 40°C, to obtain a milled composition comprising particles of coffee grounds having a d95 value of 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: • from 2% to 25% of coffee grounds with a d95 value of less than or equal to 10 µm, • at least 0.5%, preferably at least 0.8%, of a dispersant, the weight ratio of the dispersant to the raw coffee grounds being greater than or equal to 10%.

Description

[0001] DESCRIPTION

[0002] Compositions of inks based on coffee grounds and their preparation process

[0003] FIELD OF INVENTION

[0004] The present invention relates to coffee ground-based ink compositions, particularly intended for use as printing ink, and their preparation process.

[0005] STATE OF THE ART

[0006] The inks used today in the printing industry, particularly for printing systems (e.g., flexography, screen printing or zero-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.

[0007] There are two types of inks: dye-based inks and pigment-based inks.

[0008] Dye-based inks are composed of water-soluble dyes. These dyes can be of natural origin (derived from certain plants, for example) or synthetic (the majority). Dye-based inks have the advantage of very low light diffusion, resulting in saturated and vibrant colors, and are less expensive than pigment-based inks. However, the dyes are sensitive to light, humidity, and ozone.

[0009] 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.

[0010] In black inks, the most commonly used pigment is carbon black, generally considered environmentally unfriendly because it comes from non-renewable sources, and its manufacturing process is very energy-intensive and / or produces significant waste or toxic byproducts. For this reason, 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.

[0011] Alternative inks based on plant-derived pigments, such as coffee grounds, have been described in the prior art. Coffee grounds are indeed a prime source of pigment, as they are a common waste product, readily available, and easy to collect. The prior art generally describes processes in which the coffee grounds are ground, possibly with additives, or 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 in documents WO 2007 / 141557, WO 2008 / 047347, and US11517141.

[0012] However, prior art processes for preparing inks from coffee grounds do not allow for the full utilization of the coffee grounds and still generate too much coffee waste. Indeed, the processes described in WO 2007 / 141557, WO 2008 / 047347 and US11517141 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 from the consumption of coffee.

[0013] 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 (especially on an industrial scale), inexpensive, and which allow the entire coffee grounds to be utilized while ensuring good quality of the pigment ink obtained.

[0014] DESCRIPTION OF THE INVENTION

[0015] The invention aims to overcome these problems through the implementation of a process including a grinding step at a temperature less than or equal to 40°C of a composition comprising coffee grounds.

[0016] The average particle size of a pigment ink, regardless of its field of application, must be low, generally less than or equal to 10 pm, to guarantee reproducibility, ease of use and aesthetics.

[0017] Furthermore, in a non-impact printer, and particularly an inkjet printer, the ink is dispensed using nozzles, which can become clogged if the pigments have a certain value. 95 greater than 1 pm.

[0018] However, the plaintiff observed that if grinding took place at a temperature of 40°C or higher, it was not possible to obtain such average particle sizes with good long-term stability due to the occurrence of agglomeration or re-agglomeration of the coffee grounds particles. Without being bound by any particular theory, the degradation and / or gelation of the polysaccharides naturally present in coffee grounds would generate these agglomeration / re-agglomeration phenomena, which are detrimental to obtaining the desired average particle size, as such degradation / gelation occurs at temperatures above approximately 40°C.

[0019] It should be noted that to maintain the grinding temperature at 40°C or lower, the raw coffee grounds suspension must be cooled during grinding. Without cooling, the raw coffee grounds suspension heats up and reaches temperatures above 40°C, leading to the agglomeration phenomena mentioned above. Furthermore, unlike some inks used in the printing or art sectors, the pigment ink composition according to the invention requires very little, or even eliminates, the use of binders to ensure the formation of a continuous and uniform film, thus improving ink application on a substrate such as paper.

[0020] More generally, the ink of the invention preferably comprises only non-fossil components, and advantageously non-toxic ones.

[0021] 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.

[0022] Thus, according to a first aspect, the invention relates to a process 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 whose value of d 95 is less than or equal to 10 pm.

[0023] According to another aspect, the invention relates to a pigment ink composition comprising, by weight relative to the total weight of the composition:

[0024] • 2 to 25%, including 4 to 25% coffee grounds with a value of 95 less than or equal to 10 pm,

[0025] • at least 0.5% dispersing agent,

[0026] • 0 to 15% humectant,

[0027] • from 0 to 25%, preferably from 0.1 to 10%, in particular from 0.5 to 5%, of another pigment,

[0028] • 0 to 3%, preferably 0.5 to 0.8%, of a preservative,

[0029] • 0 to 10%, in particular 0 to 2%, preferably 0.02 and 1%, of an antifoaming agent,

[0030] • possibly additives such as wax (or resin), and

[0031] • a solvent comprising water, the solvent being in sufficient quantity to reach 100%.

[0032] In the ink composition, the mass ratio of the dispersing agent to the raw coffee grounds is greater than or equal to 10%. 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).

[0033] According to another aspect, the invention relates to the use of the pigment ink composition of the invention as an ink for non-impact printers, in particular inkjet printers.

[0034] According to another aspect, the invention relates to an ink cartridge, particularly 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 value of d 95 the coffee grounds is less than or equal to 1 pm, preferably less than or equal to 0.5 pm.

[0035] DETAILED DESCRIPTION OF THE INVENTION

[0036] 1 ■ Process

[0037] 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; 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 having a value of d 95 is less than or equal to 10 pm.

[0038] As understood here, the term "average particle size" refers to the average size of the grains of a powder (particularly solid pigments and coffee grounds), by volume.

[0039] The particle size distribution of powders (particularly solid pigments and coffee grounds) is generally characterized by the values ​​of d 10 , d 50 , d 90 and / or of 95 The d x , where X represents, for example, 10, 50, 90, or 95, is the Xth percentile of the particle size distribution, by volume; that is, X% of the particles have a size less than or equal to d x and (100-X)% of the particles have a size greater than d x .

[0040] The average particle size can be measured using grinding gauges and / or light diffraction techniques. The particle size distribution (values ​​of d 10 , d 50 , d 90 and / or of 95 ) is generally measured by light diffraction techniques.

[0041] Light diffusion equipment is well known in art. For example, a laser particle size analyzer, such as the Malvern MasterSizer 3000 or Beckman Coulter LS 13320, 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%, specifically around 25%.

[0042] Grind gauges allow us to determine the fineness of a dispersion, such as ink with a solid pigment. The most commonly used technique is that of grind gauges, also known as the Hegman or North gauge technique. A grind gauge is a flat steel block with flat, uniform grooves cut into its surface. These grooves extend the entire length of the block, starting at a maximum depth at one end and decreasing to zero at the other. The depth of the grooves can be read using scales engraved on the sides. With this technique, the ink containing the ground pigment is placed on a grind gauge and then spread along the groove using a scraper. During spreading, coarser particles are identified as the groove deepens.The fineness of dispersion is read on the graduated scale at the point where aggregates or particles first appear as streaks or scratches.

[0043] 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.

[0044] The lower (or upper) particle size of a powder (especially coffee grounds) is generally determined by sieving, using sieves with mesh sizes equal to X (or Y), the target lower particle size value.

[0045] Step a)

[0046] The term "raw coffee grounds" refers to coffee grounds directly collected after percolation and / or extraction with water. Raw coffee grounds as defined herein have not undergone any processing steps involving filtration and / or extraction with a solvent other than water, such as alcohol. The raw coffee grounds used in this invention are generally considered food waste.

[0047] Advantageously, the raw coffee grounds undergo 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 select 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, typically for a period of 1 to 48 hours, particularly 6 to 24 hours. Optionally, a sieving step (a1) of the raw and possibly dried coffee grounds is carried out before step (a) to obtain sieved coffee grounds with a particle size of 600 µm or less, preferably 500 µm or less.

[0048] In this embodiment, which includes a sieving step (a1), 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.

[0049] Alternatively, an optional step a2) of dry grinding the raw, preferably dried, coffee grounds can also be implemented to obtain ground coffee grounds with a particle size of 600 µm or less, preferably 500 µm or less. In this embodiment comprising a dry grinding step a2), the particle size of the ground 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 dry grinding step homogenizes the particle size of the coffee grounds, allowing all of them to be used for the process of the invention.

[0050] The dispersing agent's function is 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.

[0051] The dispersing agent is preferably non-fossil and advantageously non-toxic. It should be compatible with food contact and preferably derived from renewable sources. It is advantageously suited for use as an ink additive. It may also advantageously possess humectant properties.

[0052] Examples of dispersing agents include polymeric dispersing agents, such as copolymer dispersing agents, i.e., those resulting from the polymerization of several monomers, particularly styrenic and / or acrylic and / or maleic acid. Dispersing agents are therefore preferably high molecular weight polymers, especially copolymers. The dispersing agent is advantageously nonionic or anionic, preferably nonionic. Examples of dispersing agents usable in the process of the invention include the EDAPLAN® range marketed by Münzig Chemie, and the DISPERBYK® range marketed by BYK. Certain natural resins, such as Seedlac resin, also exhibit dispersing properties.

[0053] Seedlac resin, derived from the secretions of the insect Laccifer lacca, is composed primarily of resin acid esters bearing polar (carboxyl, hydroxyl) groups and hydrophobic chains. When dissolved in an alkaline medium, it forms a colloidal solution exhibiting an affinity for both hydrophilic and lipophilic phases, enabling it to act as a binder and a dispersing agent for solid fillers or pigments in liquid formulations. This property can be exploited in the compositions according to the invention to improve wettability and the homogeneous distribution of particles, either as a complement to or replacement for a conventional dispersant.

[0054] The mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sifted) is greater than or equal to 10%, preferably greater than or equal to 15%, in particular greater than or equal to 20%.

[0055] 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%.

[0056] Preferably, especially when the ink is intended for use in 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%, especially from 20% to 35% or from 20% to 30%.

[0057] In one variation, particularly when the ink is intended for flexographic printing, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) can be greater than or equal to 40%, and in particular greater than or equal to 50%. For example, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) varies from 50% to 100%.

[0058] Advantageously, especially when the ink is intended for use in art, and for non-impact printing techniques such as inkjet printing, the composition may contain 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 notably contributes to improving the drying of the ink.

[0059] Advantageously, especially when the ink is intended for use in 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 pH.

[0060] Preferably, the aqueous solution in 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.

[0061] 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, notably sodium sorbate or potassium sorbate.

[0062] The other pigment is preferably a black pigment, ideally non-fossil, such as vegetable charcoal. This could include the food coloring E153, charcoal derived from wood waste, or pyrolyzed coffee grounds. The purpose of this other pigment is to enhance the color intensity of the pigment ink composition.

[0063] Typically, the aqueous solution in step a) further includes an antifoaming agent and / or a humectant.

[0064] The humectant (also called a wetting agent) prevents the pigment ink composition from drying out too quickly in an inkjet printer cartridge where it may be stored. Like the other components, the humectant is preferably non-fossil-based and, advantageously, non-toxic. It should be food-safe and preferably derived from renewable sources. Typically, the humectant contains or is composed of glycerin.

[0065] Antifoaming agents are well known to those skilled in the art. An antifoaming agent suitable for pigment ink formulations, preferably non-fossil-based, and advantageously non-toxic, should be chosen. Examples of antifoaming agents usable in the process of the invention are the AGITAN® antifoaming agents marketed by Münzig Chemie or the BYK® antifoaming agents such as BYK®94, marketed by BYK.

[0066] The ink composition may also include a resin, particularly when the ink composition is intended for flexography. The resin can be natural or synthetic. Examples of synthetic resins include acrylic resins, polyamide resins, and polyethylene resins, especially high-density polyethylene. Examples of natural resins include gums, particularly shellac. Preferably, a natural resin, and especially shellac, should be chosen. Alternatively, in some variations, a polyamide resin may be used.

[0067] The ink may also include a buffering agent to control the pH, and / or an amine, which helps in particular to solubilize any resins (or waxes).

[0068] Step b) Step b) of grinding produces a ground composition comprising coffee grounds particles with a value of d 95 is less than or equal to 10 pm.

[0069] The d 95 is the 95th percentile of the particle size distribution, by volume, meaning that 95% (by volume) of the particles have a size less than or equal to d 95 and 5% (by volume) of the particles are larger than the d 95 .

[0070] Typically, step b) of grinding is implemented by a ball mill or an attrition machine, advantageously including a temperature control system suitable for maintaining 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.

[0071] In some embodiments, the ball mill or 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.

[0072] 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.

[0073] The grinding stage is generally continued either for a predetermined duration or until a value of a measurement using a fineness gauge or a value of d 95 be less than or equal to a predetermined value.

[0074] Specific embodiments

[0075] The value of d 95 of the ground composition is in particular less than or equal to 1 pm, preferably less than or equal to 0.5 pm.

[0076] The size of the beads, the grinding speed and / or the specific energy input can be adjusted during the implementation of step b) to obtain a composition comprising particles whose value of d 95 is less than or equal to 1 pm. Preferably, in this embodiment, the mass ratio of the dispersing agent to the raw coffee grounds (optionally dried and / or sieved and / or ground) 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 and / or ground) 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 and / or ground) ranges from 20% to 30%.

[0077] Step c) optional

[0078] 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.

[0079] In some variations, the aqueous composition may also include a resin, particularly when the ink composition is intended for flexography. Alternatively, the resin can be added to the ground composition obtained in step b), or to the mixture of this composition with the aqueous composition.

[0080] The resin can be natural or synthetic. The resin, whether natural or synthetic, can be as described in step a). Preferably, a natural resin should be chosen, and in particular shellac.

[0081] The aqueous composition used for dilution, optionally including a resin, may also include another pigment or a pigment dispersion to adjust the color of the final composition. Specifically, the pigment may be black. Thus, the other pigment, particularly a black pigment, can be added either in step a) suspension or in step c) dilution.

[0082] The process may further include a step (d) of adding a pigment to the ground composition obtained in step (b) or to the diluted composition obtained in step (c). The pigment will preferably be in the form of a dispersion in a solution comprising a solvent and optionally one or more additives selected from a resin, and optionally a dispersing agent. The resin may 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, gum shellac, or gum seedlac.

[0083] In some embodiments, the process comprises: a) Drying raw coffee grounds to obtain dried raw coffee grounds; a) Suspending dried raw coffee grounds in an aqueous solution comprising 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 dispersed coffee grounds suspension; 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 having a value of d 95 is less than or equal to 10 pm.

[0084] In some embodiments, the process comprises: a1) Sieving raw coffee grounds to obtain sieved coffee grounds with a particle size of 600 µm or less, preferably 500 µm or less; a) Suspending the 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 dispersed coffee grounds suspension; b) Grinding the dispersed coffee grounds suspension at a temperature of 40°C or less to obtain a ground composition comprising coffee grounds particles with a particle size of 95 is less than or equal to 10 pm.

[0085] In some embodiments, the process comprises: a) Drying raw coffee grounds to obtain dried raw coffee grounds; a) Sieving the dried raw coffee grounds to obtain sieved coffee grounds with a particle size of 600 µm or less, preferably 500 µm or less; a) Suspending the 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 dispersed coffee grounds suspension; b) Grinding the dispersed coffee grounds suspension at a temperature of 40°C or less to obtain a ground composition comprising coffee grounds particles with a particle size of 95 is less than or equal to 10 pm.

[0086] In embodiments including a step a1), this step a1) advantageously includes 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.

[0087] 2. Composition of pigment ink

[0088] The invention also relates to a pigment ink composition comprising, by weight relative to the total weight of the composition:

[0089] • 2 to 25%, including 4 to 25% coffee grounds with a value of 95 less than or equal to 10 pm,

[0090] • at least 0.5% dispersing agent,

[0091] • 0 to 15% humectant,

[0092] • from 0 to 25%, preferably from 0.1 to 10%, in particular from 0.5 to 5%, of another pigment,

[0093] • 0 to 3%, preferably 0.5 to 0.8%, of a preservative,

[0094] • 0 to 10%, in particular 0 to 2%, preferably 0.02 and 1%, of an antifoaming agent,

[0095] • possibly additives such as wax (or resin), and

[0096] • a solvent comprising water, the solvent being in sufficient quantity to reach 100%.

[0097] The ink composition may also include a resin, particularly when the ink composition is intended for flexography. The resin may be natural or synthetic. Examples of synthetic resins are acrylic resins or polyamide resins. Examples of natural resins are gums, especially shellac. Preferably, a natural resin, and in particular shellac, should be chosen. If the composition contains shellac as a binder, it can also act as a dispersant. Alternatively, in some variations, a polyamide resin may be chosen.

[0098] The pigment ink composition can be obtained by the process of the invention. Thus, in the ink composition, the mass ratio of the dispersing agent to the raw coffee grounds is greater than or equal to 10%.

[0099] Any solid compound dispersed in the composition will advantageously possess a value of 95 less than or equal to 10 pm.

[0100] The composition may include 4 to 20%, by weight, of coffee grounds with a value of 95 less than or equal to 10 pm, in relation to the total weight of the composition.

[0101] 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.

[0102] The solvent comprises, or preferably consists of, water.

[0103] According to some embodiments, the pigment ink composition is free of sulfur, in particular elemental sulfur.

[0104] The invention makes it possible to significantly reduce, or even eliminate, the use of binders. Thus, the pigment ink composition is advantageously free of binders, particularly alginate gum.

[0105] As previously stated, the dispersing agent, humectant, preservative, other pigment, and antifoaming agent are preferably non-fossil and advantageously non-toxic. They should be compatible with food contact and preferably derived from renewable sources. Ideally, they are suitable for use as ink additives.

[0106] The dispersing agent, the humectant, the preservative, the other pigment and the antifoaming agent may be as defined above for the process.

[0107] Examples of dispersing agents include polymeric dispersing agents, such as copolymer dispersing agents, i.e., those resulting from the polymerization of several monomers, particularly styrenic and / or acrylic and / or maleic acid. Dispersing agents are therefore preferably high molecular weight polymers, especially 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 marketed by BYK. The mass ratio of the dispersing agent to the raw coffee grounds (optionally dried and / or sieved) is greater than or equal to 10%, preferably greater than or equal to 15%, and in particular greater than or equal to 20%.

[0108] Preferably, especially when the ink is intended for use in 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%, especially from 20% to 35% or from 20% to 30%.

[0109] In one variation, particularly when the ink is intended for flexographic printing, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) can be greater than or equal to 40%, and in particular greater than or equal to 50%. For example, the mass ratio of the dispersing agent to the raw coffee grounds (possibly dried and / or sieved) varies from 50% to 100%.

[0110] According to some variants, 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%.

[0111] Preferably:

[0112] - the humectant comprises or is made up of glycerin, and / or

[0113] - the preservative comprises or is made up of sorbic acid or a salt thereof, in particular sodium sorbate or potassium sorbate.

[0114] The other pigment is preferably a black pigment, such as vegetable charcoal. This could include the food pigment E153, or pyrolyzed coffee grounds. The other pigment advantageously has a value of 95 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%.

[0115] Advantageously, especially when the ink is intended for use in art, and for non-impact printing techniques such as inkjet printing, the composition may contain 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 notably contributes to improving the drying of the ink.

[0116] Advantageously, especially when the ink is intended for use in 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 pH.

[0117] In some variations, the dispersing agent has humectant properties: it then acts as a humectant. In these variations, preferably, the composition does not include any other humectant, i.e., it contains 0% by weight of any humectant other than the dispersing agent.

[0118] The ink may also include a buffering agent to control the pH, and / or an amine, which helps in particular to solubilize any resins (or waxes).

[0119] Ready-to-use ink

[0120] According to certain variants, particularly when the ink is intended for use in art and for non-impact printing techniques, such as inkjet printing, the pigment ink composition is ready to use, meaning it can be used directly without prior dilution.

[0121] According to these variations, 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 advantageously includes 4 to 5% by weight of coffee grounds with a value of 95 less than or equal to 10 pm, in relation to the total weight of the composition.

[0122] 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.

[0123] Typically, the "ready-to-use" pigment ink composition includes at most 2%, or at most 1.5% by weight of dispersing agent, relative to the total weight of the composition.

[0124] Preferably, especially when the ink is intended for use in 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%, especially from 20% to 35% or from 20% to 30%.

[0125] 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.

[0126] 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.

[0127] According to certain embodiments, particularly when the pigment ink composition is intended for use in printing (especially non-impact printing, preferably inkjet), the value of d 95 The amount of coffee grounds is less than or equal to 1 µm, preferably less than or equal to 0.5 µm. 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 value of d 95 the coffee grounds is less than or equal to 1 pm, preferably less than or equal to 0.5 pm.

[0128] According to certain embodiments, particularly in art applications, the "ready-to-use" pigment ink composition has a viscosity of 3 to 20 mPa.s (1000 s -1Viscosity is measured, for example, using a rheometer, such as the 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 .

[0129] According to certain embodiments, particularly in flexography, the "ready-to-use" pigment ink composition has a viscosity of 70 to 100 mPa.s (1000 s -1 ).

[0130] Finally, the pigment ink composition preferably has a density of 1,000 to 1,500 kg / m³. 3 .

[0131] Concentrated ink

[0132] Depending on the variant, particularly when the ink is intended for use in flexography, the pigment ink composition may be in concentrated form, meaning that it will need to be diluted before use.

[0133] The concentrated pigment composition typically includes 5 to 20% by weight of coffee grounds with a value of 95 less than or equal to 10 pm, in relation to the total weight of the composition.

[0134] 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.

[0135] 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%.

[0136] In some variations, particularly when the ink is intended for flexographic printing, the concentrated composition also includes a resin, specifically as defined in step a) above. In other variations, the concentrated composition is resin-free.

[0137] 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.

[0138] Preferably, the sum of the black pigment and coffee grounds content is less than or equal to 25%.

[0139] 3. Uses The invention also relates to the use of the pigment ink composition of the invention as an ink for art, in particular for drawing, painting, or calligraphy. The pigment ink composition of the invention can also be used as an ink for screen printing, flexography, and indirect printing techniques, such as offset printing.

[0140] The pigment ink composition of the invention can also be used, in particular when the value of d 95 coffee grounds are less than or equal to 1 pm, preferably less than or equal to 0.5 pm, as ink for non-impact printers, including inkjet printers.

[0141] The pigment ink composition of the invention can be used on various substrates, such as paper, textiles, cardboard, or plastic film (especially for packaging).

[0142] 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 value of d 95 the coffee grounds is less than or equal to 1 pm, preferably less than or equal to 0.5 pm.

[0143] EXAMPLES

[0144] The following examples are given for illustrative purposes only, but should in no way be considered as limiting the present invention.

[0145] Materials and Methods

[0146] The ingredients in Table 1 below were used in the examples of the present invention.

[0147] [Table 1]

[0148] Particle size measurement methods Particle size analyses are performed using a Mastersizer 3000 laser diffraction particle size analyzer (Malvern Panalytical), with a light shading percentage of 25%.

[0149] Rheological tests

[0150] Rheology measurements are performed with a rheometer, such as an MCR302 rheometer marketed by Anton Paar, with a Plate-Plate type geometry (50 mm), a 0.5 mm measurement slit, at 25°C, for 285 to 286 s, and a shear rate ranging from 0.1 to 1000 s⁻¹ 1 .

[0151] Example 1 - preparation of raw coffee grounds

[0152] The raw coffee grounds are placed in an oven at 65°C for 2 to 24 hours.

[0153] Depending on the implementation, the dried raw coffee grounds (MDC) can be dry-ground to obtain a particle size distribution with a D95 of 500 µm or less, or alternatively sieved using a 500 µm stainless steel sieve. This step aims to facilitate subsequent dispersal or grinding steps, particularly in formulations with a high coffee grounds content.

[0154] Approximately 5% by volume of the MDC constitutes a coarse fraction removed during sieving.

[0155] Dried MDC (and then possibly ground dry or sieved) can be used directly in ink formulations, or stored in an airtight container, made of plastic or glass, with a moisture-proof system, for later use.

[0156] Example 2 - Influence of temperature during grinding

[0157] Composition 1 shown in Table 2 below was used to perform the grinding tests in Example 2.

[0158] [Table 2] The grinding stage was carried out in an Emax grinder (marketed by RETSCH). The grinding was performed with zirconium (ZrO) beads, with a diameter of 0.5 mm.

[0159] The grinding speed is set at 1200 rpm.

[0160] The room is equipped with a cooling system.

[0161] 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, and even 30 pm.

[0162] When the temperature control device is set to a target temperature of 36°C, the final composition obtained is fluid. Adjusting the grinding time and pellet size then allows a specific value to be obtained. 95 less than or equal to 10 pm.

[0163] Example 3 - Implementation of the process of the invention

[0164] Compositions 2 and 3 shown in Table 3 below were used to perform the grinding tests in Example 3.

[0165] [Table 3]

[0166] The d 95 the raw coffee grounds used in compositions 2 and 3 is approximately 598 pm.

[0167] The grinding stage was carried out in a LabStar mill (marketed by NETZSCH Feinmahltechnik). The grinding was performed with zirconium (ZrO) beads of varying diameters.

[0168] The grinding chamber is equipped with a cooling device, set so that the internal temperature does not exceed 30°C.

[0169] The values ​​of d 10 , d 50 and 90 The results shown in Table 4 below were obtained with compositions 2 and 3:

[0170] [Table 4]

[0171] We can see that by adjusting the size of the balls, the speed and the duration of grinding, we can obtain a composition comprising particles whose value of d 95 is less than or equal to 10 pm and descends to a value of d 95 less than 1 pm.

[0172] Example 4 - Implementation of the process of the invention with a natural resin-type dispersing agent

[0173] Step a) of suspension

[0174] A grinding varnish is made by mixing Seedlac gum (in the form of a solution containing between 10% and 40% resin by weight, between 5% and 25% amines, and water) at high speed for 20 to 240 minutes. Then, while stirring, the antifoaming agent 2, the other black pigment (based on pyrolyzed coffee grounds), and the coffee grounds from Example 1 are added.

[0175] Step b) of grinding

[0176] The coffee grounds suspension obtained in step a) is then introduced into a PML2 grinder (marketed by Bühler). Grinding was carried out using zirconium oxide beads with a diameter between 0.3 mm and 3 mm.

[0177] The grinding chamber is equipped with a cooling device, set so that the internal temperature does not exceed 35°C.

[0178] This results in a ground composition comprising coffee grounds particles with a d95 value less than or equal to 1 pm.

[0179] The ground composition is then transferred into an agitator, and the preservative and a high-density polyethylene wax (from Aquacer®) are added under low-speed agitation.

[0180] The quantities of ingredients used are reported in Table 5.

[0181] [Table 5] Preservative 0.2

[0182] The resulting ink has a viscosity that meets the standards for flexographic printing. It can be used as is, or diluted with water, possibly mixed with a resin (or varnish).

[0183] Example 5 - Implementation of the process of the invention for concentrated composition

[0184] Step a) of suspension

[0185] Mix 15.3 g of Seedlac gum (as a 30% resin solution by weight) and 66.2 g of water at high speed for 20 minutes to 4 hours. Then, while stirring, add 7.7 g of dispersing agent and 10.6 g of coffee grounds.

[0186] Step b) of grinding

[0187] The coffee grounds suspension obtained in step a) is then introduced into a PML2 grinder (marketed by Bühler). The grinding was carried out as in example 4.

[0188] This results in a ground composition comprising coffee grounds particles with a d95 value less than or equal to 1 pm.

[0189] The ground composition is then transferred to a stirrer, and 0.2 g of preservative is added under low-speed stirring.

[0190] [Table 6]

[0191] Components

[0192] Example 5 - Application for art

[0193] The ink composition of trial 5 (example 3) has been tested in applications for art, including drawing and calligraphy.

[0194] The results obtained are entirely similar to those of a commercial ink using petroleum-based pigments, both in terms of aesthetic quality and ease of use. Example 6 - Printing tests with an inkjet printer

[0195] 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.

[0196] The filled cartridge is used in an Epson WORKFORCE WF-2010W inkjet printer (home printer) or industrial (pilot scale machine).

[0197] 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.

[0198] Example 7 - Flexography Tests

[0199] [Table 7]

[0200] Composition 7 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.

[0201] We obtain particles whose value of d 95 is less than or equal to 10 pm, or even less than or equal to 1 pm, depending in particular on the duration of the grinding.

[0202] 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 needed.

[0203] This composition including the resin is then used to produce flexographic prints on a Flexiproof brand machine, on paper support, label and flexible packaging.

[0204] 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

DEMANDS 1. A process 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; 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 having a value of d 95 is 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 method according to any one of claims 1 to 6, characterized in that the value of d 95 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: • 2 to 25%, in particular 4 to 25%, of coffee grounds with a value of 95 less than or equal to 10 pm, • at least 0.5%, preferably at least 0.8%, of a dispersing agent, • possibly additives such as a resin, and • a solvent comprising water, the solvent being in sufficient quantity to reach 100%, the mass ratio of the dispersing agent to the raw coffee grounds being greater than or equal to 10%.

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 it further comprises: • 0 to 15% humectant, • from 0 to 25%, preferably from 0.1 to 10%, in particular from 0.5 to 5%, of another pigment, • 0 to 1%, preferably 0.2 to 0.8%, of a preservative, • 0 to 10%, in particular 0 to 2%, preferably 0.02 and 1%, of an antifoaming agent. • 0 to 10%, in particular 0 to 7%, preferably 0.5 to 5% of a resin 11. Ink composition according to claim 10, 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, and / or - the pigment is a black pigment such as vegetable charcoal or pyrolyzed coffee grounds.

12. Pigment ink composition according to any one of claims 8 to 11, characterized in that the value of d 95the 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 an ink for art, screen printing, flexography, and indirect printing techniques, such as offset printing.

15. Use of the pigment ink composition of claim 12 as an 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.

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