Deinkable ink with high bio-renewable content

Abstract

The present invention relates to a printing ink composition comprising one or more keratin-based pigments and water, wherein the one or more keratin-based pigments have an average particle size of 3000 nm or less.

Description

[Technical Field]

[0001] The present application relates to a printing ink composition comprising one or more keratin-based pigment(s) and water. Advantageously, inks according to the present invention have advantageous color and lightfastness properties compared to traditional dye-based inks. Furthermore, substrates printed with inks according to the present invention can typically be deinked using a mildly alkaline pH aqueous solution, thereby allowing the substrate to be more easily recycled and reused. Thus, printing ink compositions according to the present invention can improve sustainability in, for example, the packaging and textile industries. [Background technology]

[0002] Dyeing and printing of substrates (e.g., textiles, paper, and plastics) with dye-based inks produces printed substrates with dyes either covalently bound to the fibers (reactive direct dyes), e.g., cellulose fibers in the case of cellulose-based substrates, or alternatively, strongly ionically bound (acid dyes), e.g., in the case of silk, synthetic nylon, and other substrates.

[0003] With an increasing market focus on sustainability and recycling, de-inking of such substrates has become more important in providing fully recyclable textiles, paper, and plastics. Typically, extremely harsh chemical treatments are required to remove dyes from textiles, paper, and plastics, including steps such as bleaching and oxidation. Furthermore, the wastewater can be heavily contaminated with chemicals that are harmful to the environment.

[0004] The present invention solves these problems by providing a printing ink composition comprising a keratin-based pigment and water that provides for convenient deinking under simple aqueous alkaline conditions. Advantageously, the printing ink composition according to the present invention is suitable for inkjet printing.

[0005] EP 3,341,209 (Plastipak Packaging) relates to ink compositions for digital printing containing an ink removal-promoting additive, specifically an ink removal-promoting additive having a Tg<130°C in an amount of 5-20% w / w. Exemplary ink removal-promoting additives include styrene maleic anhydride (SMAN) binders having an acid number of 150-205 mg KOH / g. EP 3,341,209 specifically relates to printing on plastic recyclable articles and the use of a removal fluid having a pH of 12-13 at 70-90°C.

[0006] WO 2020 / 026161 (Wool Source) describes the application of keratin-derived pigments. The keratin-derived pigments described in WO 2020 / 026161 are not ground before use. WO 2020 / 026161 does not disclose the use of keratin-derived pigments for inkjet printing of substrates (e.g., textiles, paper, and plastics).

[0007] Citation or identification of any document in this application is not an admission that such constitutes prior art to the present invention. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] European Patent Application Publication No. 3,341,209 [Patent Document 2] International Publication No. 2020 / 026161 Summary of the Invention [Means for solving the problem]

[0009] In a first aspect, the present invention provides a print ink composition comprising one or more keratin-based pigments and water, wherein the one or more keratin-based pigments have an average particle size of 3000 nm or less. Preferably, the one or more keratin-based pigments have an average particle size of 2000 nm or less, preferably 1000 nm or less, more preferably 600 nm or less.

[0010] Preferably, the one or more keratin-based pigments have an average particle size of from 50 nm to 3000 nm, preferably from 75 nm to 2000 nm, more preferably from 100 nm to 1000 nm, even more preferably from 125 nm to 600 nm.

[0011] Unless otherwise specified, the term "particle size" or "average particle size" as used herein refers to the volume distribution median particle diameter (the equivalent spherical diameter corresponding to 50% of the volume of all particles as read on a cumulative distribution curve showing the relationship between volume % and particle diameter, often referred to as the "D(v,0.5)" value or Dv50). Unless otherwise specified, particle size is suitably measured by dynamic light scattering (DLS). Preferably, particle size is suitably measured by dynamic light scattering (DLS) using a Malvern Zetasizer. Unless otherwise specified, particle size is suitably measured by DLS in deionized water at 20°C.

[0012] In the context of the present invention, "nanoscale" refers to particles having one dimension less than 100 nm, which is the commonly accepted definition of a nanoparticle.

[0013] As will be understood by those skilled in the art, keratin-based pigments can be obtained by dyeing keratin particles. Typically, keratin particles suitable for use in the present invention are prepared from keratin fibers derived from animal sources, including animal hair, wool, or fur (e.g., from sheep, goats, alpacas, cows, pigs, etc.); animal horns, nails, claws, and hooves (e.g., from cattle, goats, antelopes); and animal feathers and scales (e.g., from birds and fish). Preferably, the keratin particles are derived from sheep wool. The keratin particles are dyed using materials suitable for dyeing animal fibers. For example, dyes suitable for dyeing wool, such as acid dyes, including the Sandolan, Lanasyn, and Lanasan ranges. These dyes can be used under typical industrial dyeing conditions to produce dyed keratin particles in a range of colors and shades. WO 2020 / 026161 discloses a method for preparing keratin particles and dyeing the keratin particles. WO 2020 / 026161 does not disclose grinding the dyed keratin particles before use.

[0014] Preferably, the keratin-based pigment is a dyed keratin particle. Preferably, the keratin-based pigment is an acid-dyed keratin particle (i.e., the keratin particle is dyed with an acid dye).

[0015] Typically, the keratin-based pigments according to the present invention can be considered lake pigments. As will be understood by those skilled in the art, lake pigments are made by precipitating a water-soluble dye with an inert binder, in this case, keratin particles. As will be further understood by those skilled in the art, inks containing lake pigments typically have superior lightfastness compared to traditional dye-based inks.

[0016] The present invention also provides a method for preparing a print ink composition comprising one or more keratin-based pigments and water, the method comprising the step of milling a dispersion comprising water and one or more keratin-based pigments.

[0017] The keratin-based pigments present in the compositions of the present invention are milled to obtain the required particle size. Milling can be carried out using a suitable bead milling machine, such as an Eiger laboratory bead mill (available from Eiger Torrance Ltd.) equipped with suitable grinding media. Suitable grinding media include 0.8 mm ytterbium-zirconium oxide grinding media. Preferably, milling is carried out for up to 60 minutes, more preferably up to 45 minutes, more preferably up to 30 minutes, and more preferably up to 20 minutes. As used herein, "up to" is inclusive, so that "up to" 60 minutes (for example) includes 60 minutes.

[0018] Preferably, the milling is carried out for 1 to 60 minutes, more preferably 5 to 45 minutes, even more preferably 8 to 30 minutes, and most preferably 10 to 20 minutes.

[0019] Preferably, milling is carried out for 45 minutes, more preferably 30 minutes, and even more preferably 20 minutes.

[0020] Preferably, milling is carried out to reduce the average particle size of the keratin-based pigment to 3000 nm or less, preferably 2000 nm or less, more preferably 1000 nm or less, and even more preferably 600 nm or less. Preferably, milling is carried out to reduce the average particle size of the keratin-based pigment to 50 nm to 3000 nm, preferably 75 nm to 2000 nm, more preferably 100 nm to 1000 nm, and even more preferably 125 nm to 600 nm.

[0021] It has been discovered that printing ink compositions according to the present invention containing keratin-based pigments having the required particle size are more lightfast and colorfast than corresponding inks containing conventional dyes. Additionally, printing ink compositions according to the present invention containing keratin-based pigments having the required particle size have increased color intensity compared to compositions containing larger keratin-based pigments. Preferably, the keratin-based pigment contains alpha-keratin (α-keratin). As understood by those skilled in the art, alpha-keratin is a polypeptide chain that forms an alpha-helix (α-helix). Two of these alpha-helices typically twist together to form a helical structure (often referred to as a coiled coil). Without wishing to be bound in this regard, the inventors hypothesize that milling the keratin-based pigment to achieve the required particle size results in a partial unwinding of the keratin helical structure. In particular, it is hypothesized that milling can break disulfide and other cross-linking bonds in the keratin structure, thereby making the keratin more open and resulting in increased color intensity. In addition, the small particle size (ie, less than 3000 nm) that can be achieved by milling keratin-based pigments means that the resulting ink compositions are suitable for ink jet printing.

[0022] Preferably, the keratin-based pigment used in the present invention is milled before use. Preferably, the milled keratin-based pigment comprises a keratin-based pigment in which the helical structure of the keratin is partially unwound. Preferably, the milled keratin-based pigment comprises alpha-keratin in which the helical structure of the keratin is partially unwound. Unless otherwise specified, a partially unwound helical structure means that some of the cross-links in the keratin helical structure are broken. For example, without wishing to be bound in this regard, the inventor hypothesizes that milling breaks at least 5% of the cross-links in the keratin helical structure. The partially unwound helical structure can be observed by electron microscopy, for example, scanning electron microscopy.

[0023] Preferably, the printing ink composition of the present invention has a viscosity of 4 to 15 cP when measured at 32°C using a Brookfield DVII+Pro viscometer fitted with an 00 spindle. More preferably, the printing ink composition of the present invention has a viscosity of 4 to 15 cP when measured at 32°C using a Brookfield DVII+Pro viscometer fitted with an 00 spindle at 60 rpm.

[0024] Furthermore, inks according to the present invention are more easily removed from the surface of substrates (particularly textiles and paper) than conventional dyes, without the need for harsh chemical treatments, such as the use of strong oxidizing or bleaching agents, such as sodium hypochlorite or hydrogen peroxide. Inks according to the present invention are therefore advantageous because they improve the recyclability of printed substrates.

[0025] When attempting to remove reactive dyes that are covalently bound to textiles such as cotton, or acid dyes that are strongly ionically bound to textiles such as polyamides, harsh chemical and often microbial treatments, often in combination with bleaching agents, must be used. Even these harsh oxidation or bleaching methods are nearly impossible to remove sufficient traces of dye from textiles or other substrates. In this invention, we address the deinking problem by using a printing ink that contains small particles of keratin-based pigment particles (i.e., keratin-based pigment particles having an average particle size of 3000 nm or less) deposited by means of inkjet printing, and that can be deinked with a simple, slightly alkaline aqueous solution (e.g., an aqueous solution having a pH of 10-11 at approximately 25-65°C).

[0026] Preferably, the printing ink according to the present invention is water-based. Unless otherwise specified, a water-based ink comprises at least 20% by weight of water, at least 25% by weight of water, at least 30% by weight of water, at least 40% by weight of water, or at least 50% by weight of water. The amount of water is at most 95% by weight, at most 90% by weight, at most 85% by weight, at most 80% by weight, at most 75% by weight, or at most 70% by weight. The range of water in the composition is typically from about 30% to about 90% by weight, more typically from about 40% to about 80% by weight, or even more typically from about 50% to about 70% by weight.

[0027] The printing ink according to the present invention may optionally contain one or more humectants in addition to water, i.e., the carrier liquid for the ink is water and a humectant. The humectant is preferably derived from renewable resources. Examples of suitable humectants include polyols, such as glycerol, ethylene glycol, diethylene glycol, monopropylene glycol, and combinations thereof. Preferably, the ink composition according to the present invention includes glycerol. Typical amounts of humectants in the composition are 0.5% to 35% by weight, and preferably the humectant is present in an amount of 5% to 30% by weight.

[0028] The printing ink according to the present invention may optionally further comprise one or more additional materials selected from the group consisting of water retention agents (solid or liquid), wetting agents, dispersants, surfactants, binders, viscosity modifiers and preservatives.

[0029] Preferably, the printing ink according to the present invention can further comprise a wetting agent or dispersant, preferably a dispersant. Suitable dispersants include alkyl sulfonates, fatty sulfonates, and alkylaryl sulfonates. As will be understood, fatty sulfonic acids are sulfonic acids with an aliphatic chain that is either saturated or unsaturated. Preferably, the dispersant is a coconut oil or palm oil-based dispersant, such as sodium lauryl sulfate. Preferably, the dispersant is sodium lauryl sulfate. When used, the dispersant is typically present in an amount of 0.1% to 5% by weight of the composition.

[0030] The printing ink according to the present invention may optionally further comprise a viscosity modifier, preferably selected from the group consisting of guar gum, gum arabic, xanthan gum, trehalose and combinations thereof.

[0031] The printing ink according to the present invention may optionally further comprise one or more antimicrobial agents (e.g., Proxel GXL) and / or one or more antifoaming agents (e.g., Airase 5355). If used, the antimicrobial agents are typically present at 0.05% to 3% by weight. If used, the antifoaming agents are typically present at 0.01% to 1.5% by weight.

[0032] Preferably, the printing ink according to the invention is applied to a suitable substrate and then heated. Upon heating, the ink is fixed by curing at temperatures up to 220°C, depending on the temperature stability of the substrate, without thermal degradation. In most cases, significantly lower curing temperatures are required. Preferably, the ink is cured at temperatures between 50 and 220°C, more preferably between 80 and 190°C.

[0033] The inks can be cured on a variety of plastics, textiles, paper (including cardboard and wallpaper), metal, glass, and other substrates and can exhibit excellent adhesion and rub-resistance properties. It is hypothesized that the additional improved rub-resistance comes from the keratin pigment particles, which, due to their hydrophobicity, actually rise to the surface of the coating upon curing. This imparts a softer feel or "hand" to the surface of the printed substrate and also improves lightfastness, as the keratin protects the dye from UV degradation.

[0034] Preferably, the ink composition of the present invention is suitable for inkjet printing, and more preferably, the ink composition of the present invention is an inkjet printing ink.

[0035] The present invention also provides a method of deinking a substrate comprising an ink composition as defined herein printed and dried on the substrate, the method comprising the step of immersing the printed substrate in a deinking solution comprising alkaline water having a pH of from 7.1 to 14.0.

[0036] As understood in the art, the term "deinking" or "deinking process" refers to the removal of ink from a printed substrate.

[0037] Deinking can be easily accomplished by immersing the object (i.e., the printed substrate) in an alkaline solution, preferably a weak alkaline solution, such as triethanolamine in water having a pH of 10-11, at approximately 25-65°C. The ink is visibly removed from all substrates by hydrolysis of the bonds formed during curing. Furthermore, the basic removal liquid can be recycled to recover keratin and / or dyes, if desired. Similarly, the deinked substrate can be recycled and reused.

[0038] One additional technical advantage of the present invention is the sustainability of the ink, including an exceptionally high Bio-Renewable Carbon (BRC) content that can go up to greater than 90%. Furthermore, for substrates such as textiles and paper containing inks that are deinked after use in a convenient manner, the ink and its ability to allow the textiles and paper to be recycled and reused. Both offer significant advantages, particularly in packaging-related and textile-related applications, where sustainable and deinkable inks are not currently available.

[0039] EP 3,341,209 (Plastipak Packaging) states that recyclable plastic articles coated with an ink containing a base ink and an additional ink removal-promoting additive can be deinked using a basic solution having a pH of 12-13 at a temperature range of 70-90°C. EP 3,341,209 discloses that styrene-maleic anhydride copolymers can be used as the ink removal-promoting additive, having a Tg in the range of 50-110°C and an acid value in the range of 150 mg KOH / g to 205 mg KOH / g. Importantly, in EP 3,341,209, the content of the ink removal-promoting material, which is exclusively styrene-maleic anhydride, is 5-20% (w / w) in the ink.

[0040] Preferably, the ink according to the present invention comprises less than 5% (w / w) of a polymeric binder selected from styrene-maleic anhydride, styrene-maleic acid, acrylics, polyurethanes, polycarbonates, and copolymers thereof. More preferably, the ink is substantially free (i.e., comprises 1% (w / w) or less) of a polymeric binder selected from styrene-maleic anhydride, styrene-maleic acid, acrylics, polyurethanes, polycarbonates, and copolymers thereof.

[0041] Preferably, the ink according to the present invention comprises less than 5% (w / w) of an acid-functional polymeric binder selected from acid-functional styrene-maleic anhydride, styrene-maleic acid, acrylics, polyurethanes, polycarbonates, and copolymers thereof. More preferably, the ink is substantially free (i.e., comprises 1% (w / w) or less) of an acid-functional polymeric binder selected from acid-functional styrene-maleic anhydride, styrene-maleic acid, acrylics, polyurethanes, polycarbonates, and copolymers thereof.

[0042] The inks of the present invention can contain low levels (i.e., less than 5% (w / w)) of carboxylic acid- or sulfonic acid-functional binders capable of chemically and covalently bonding to various textile substrates and, optionally, keratin pigment particles. Thus, the inks of the present invention can contain less than 5% (w / w) of carboxylic acid- or sulfonic acid-functional polymeric binders selected from carboxylic acid- or sulfonic acid-functional styrene-maleic anhydride, styrene-maleic acid, acrylic resins, polyurethanes, polycarbonates, and copolymers thereof. More preferably, the inks are substantially free (i.e., contain no more than 1% (w / w)) of carboxylic acid- or sulfonic acid-functional polymeric binders selected from carboxylic acid- or sulfonic acid-functional styrene-maleic anhydride, styrene-maleic acid, acrylic resins, polyurethanes, polycarbonates, and copolymers thereof.

[0043] Alternatively, the ink can include an optional binder to promote good anchoring to the substrate. When optional binders are selected for the keratin-based pigment particles, they can be from many different groups, such as acid-functional and optionally and additionally hydroxyl-functional styrene-maleic anhydride, styrene-maleic acid copolymers, acrylic polymers, polyurethanes, polycarbonates, and their various available copolymers. However, it is preferred that the optional binder (as well as any dispersants present) be derived from natural sources to maintain a high (preferably 85% or greater) biorenewable carbon (BRC) content of the ink.

[0044] Preferably, the one or more keratin-based pigments are present in at least 5% (w / w), preferably at least 7% (w / w), more preferably at least 9% (w / w). Preferably, the one or more keratin-based pigments are present in at most 15% (w / w) of the composition. Preferably, the ink composition according to the present invention comprises from about 5% to about 15% (w / w) of one or more keratin-based pigments, preferably from about 7% to about 12% (w / w) of one or more keratin-based pigments.

[0045] The pigment was found to bond well to many different textile substrates, including cotton and polyester, when printed and fixed under normal operating conditions, e.g., inkjet printing followed by thermal heat press fixing for 2 minutes at 160° C. In fact, removal of the pigment was not possible even when immersed in standard cleaning solutions.

[0046] The use of keratin-based pigments in the inks of the present invention is advantageous because the dyes can be bound to a variety of different substrates to which partially dye-based inks cannot normally be applied, and the substrates can then be easily deinked. In particular, the colorant particles (from the keratin-based pigments) can be completely removed from the substrate. In the present invention, the ink binder (if present) can form covalent or ionic bonds with the keratin pigment and, in some cases, can also form covalent or ionic bonds with the substrate. These are then broken during alkaline hydrolysis, allowing not only the substrate to be recycled, but also the dye and keratin particles.

[0047] The ink composition according to the present invention can be printed on a variety of different substrates. Examples of suitable substrates that are the subject of the present invention include, among others, plastics, textiles, paper, metals, glass, polymer films, and ceramic substrates. Suitable polymer film substrates include BOPP (biaxially oriented polypropylene), cellophane (cellulose), LDPE / HDPE (low-density and high-density polyethylene), OPP (oriented polypropylene), MET-OPP (metallized oriented polypropylene), PA (polyamide), PET (polyethylene terephthalate), MET-PET (metallized polyethylene terephthalate), PP (polypropylene), and PVC (polyvinyl chloride). Suitable metal substrates for the present invention include steel (including protected steel) and aluminum (including protected aluminum).

[0048] Substrates particularly suitable for the present invention are preferably textile and paper substrates, more preferably textile substrates.

[0049] Suitable paper substrates include wallpaper and cardboard. As understood in the art, paper is a synthetic material formed from cellulose fibers.

[0050] As understood in the art, textiles are formed by weaving, knitting, crocheting, knotting, tatting, felting, bonding, and / or flaying yarns, which themselves are formed from fibers. Textile substrates suitable for use in the present invention can be selected from cotton, rayon, silk, polyester, PET (polyethylene terephthalate), viscose, nylon, polyamide, canvas, chenille, chiffon, crepe, damask, georgette, gingham, jersey, lace, linen, polyvinyl chloride, leather, wool (e.g., cashmere wool or merino wool), modal, muslin, organza, satin, spandex, suede, taffeta, toile, tweed, twill, velvet, linen, ramie, sisal, bamboo, flax, and combinations thereof. More preferably, substrates suitable for use in the present invention are selected from cotton, polyester, and combinations thereof.

[0051] As used herein, textile substrate does not include paper.

[0052] The inks of the present invention are preferably composed primarily of biorenewable carbon (BRC)-containing materials, such that even the colorants are composed of approximately 90% biorenewable carbon. Unless otherwise specified, BRC content is determined according to ASTM D6866-18 Method B (AMS) using NIST Standard Reference Material (SRM) 4990C. In all cases, water is excluded from the BRC content. By selecting a keratin-derived pigment, preferably with a BRC content of 90% or more, and a coconut or palm oil-based dispersant, e.g., sodium lauryl sulfate, having 100% BRC, a dispersion with a high BRC content (preferably, a dispersion with a BRC content of 85% or more, more preferably, 90% or more) can then be formulated, which, by careful selection of ink components, can then lead to an ink with a high BRC content (preferably, an ink with a BRC content of 85% or more, more preferably, 90% or more). Preferably, the inks of the present invention have a BRC content of 90% or more.

[0053] The inks of the present invention are preferably highly resolubilizable, which is important for inkjet deposition processes. Resolubility is particularly important in inkjet printing because solid deposits can form in inkjet nozzles as the ink dries in the ambient air when the press is not in use. The ability of these solid particles to redissolve upon press startup (or be cleaned using a simple maintenance wipe) is termed resolubility. The inks of the present invention have been found to have exceptional resolubility, much higher than inks from the comparative example using standard textile pigment inks. The inks of the present invention have also been found to impart a soft and protective feel to treated objects and to be highly resistant to cracking. Cured films obtained from inks of the present invention preferably have improved scratch and abrasion resistance compared to using conventional organic pigments, and furthermore, the lightfastness of printed films containing keratin-derived pigments is superior to that of the corresponding dyes alone.

[0054] It has also been discovered that treatment of textile fabrics with inks containing keratin-based pigments exhibits better fastness properties than textile fabrics printed with the corresponding dye inks alone. Furthermore, while the dye-only inks could not be deinked under the weakly basic aqueous conditions described above, the inks of the present invention were readily deinked under the same conditions.

[0055] The keratin-based pigment particles used in the inks of the present invention are "sponge-like" in nature and highly compressible when deposited using an inkjet printhead, particularly with shear forces applied to the ink. In fact, inks containing such pigment particles were found to be essentially self-cleaning, and print nozzles remained free of debris or deposits during printing tests. Furthermore, the compressible nature of keratin pigment particles in inkjet printheads means that particles larger than the typically perceived size of approximately 101-150 nm for organic pigments alone can be printed using inkjet methods.

[0056] Unless otherwise specified, pH was measured at 25°C using an Oakton 510 series pH meter. DETAILED DESCRIPTION OF THE INVENTION

[0057] The present invention is further exemplified by the following series of numbered paragraphs and combinations resulting from dependencies and back references as indicated. In particular, in each instance where a range of paragraphs is described, it is noted that in connection with a term such as "the method of any one of paragraphs 1 to 5," any and all paragraphs in this range are meant to be clearly disclosed for one skilled in the art, i.e., the wording of this term should be understood by one skilled in the art as being synonymous with "the method of any one of paragraphs 1, 2, 3, 4, and 5." It is further noted that the following series of numbered paragraphs represent appropriately structured portions of the description directed to general and specific aspects of the present invention.

[0058] 1. A printing ink composition comprising one or more keratin-based pigments and water, wherein the one or more keratin-based pigments have an average particle size of 3000 nm or less. 2. The composition according to paragraph 1, wherein the one or more keratin-based pigments have an average particle size of 2000 nm or less, preferably 1000 nm or less, more preferably 600 nm or less. 3. The composition of item 1 or 2, comprising at least 30% (w / w) water, preferably at least 40% (w / w) water, more preferably at least 50% (w / w) water. 4. The composition of any preceding paragraph, comprising about 30% to about 90% (w / w) water, preferably about 40% to about 80% (w / w) water, more preferably about 50% to about 70% (w / w) water. 5. The composition of any preceding clause, comprising at least 5% (w / w) of one or more keratin-based pigments, preferably at least 7% (w / w) of one or more keratin-based pigments, more preferably at least 9% (w / w) of one or more keratin-based pigments. 6. The composition of any preceding paragraph, comprising from about 5% to about 15% (w / w) of one or more keratin-based pigments, preferably from about 7% to about 12% (w / w) of one or more keratin-based pigments. 7. The composition of any preceding clause, further comprising one or more additional materials selected from the group consisting of water retention agents (solid or liquid), wetting agents, dispersing agents, surfactants, binders, viscosity modifiers, and preservatives. 8. The composition of any preceding paragraph, comprising an acid-functional binder selected from the group consisting of acrylics, polyurethanes, styrene-maleic acid, polycarbonates, styrene-maleic anhydride, and copolymers thereof. 9. The composition of any preceding paragraph, wherein the acid-functional binder further comprises hydroxyl groups. 10. The composition of any of paragraphs 1 to 7, comprising 5% (w / w) or less of a polymeric binder selected from styrene maleic anhydride, styrene-maleic acid, acrylic resins, polyurethanes, polycarbonates, and copolymers thereof. 11. The composition of any preceding clause, having a biorenewable carbon (BRC) content of 90% or more. 12. The composition of paragraph 8 or paragraph 9, wherein the pigment to binder ratio ranges from 1:50 to 50:1 pigment particles:binder. 13. The composition of any preceding clause, suitable for deposition using a method selected from inkjet printing, flexography, nozzle coating, slot coating, screen printing, lithography, offset printing, and gravure printing, preferably suitable for deposition using inkjet printing. 14. The composition of any preceding clause which is an inkjet ink. 15. The composition of any preceding paragraph, wherein the carrier liquid for the ink is water and a humectant derived from renewable sources. 16. The composition of paragraph 15, wherein the humectant is selected from the group consisting of glycerol, ethylene glycol, diethylene glycol, monopropylene glycol, and combinations thereof, preferably, the humectant is glycerol. 17. A composition according to any preceding paragraph, comprising a preservative derived from renewable sources. 18. The composition of paragraph 17, wherein the preservative is selected from the group consisting of 2-phenoxyethanol and sodium benzoate. 19. The composition of any preceding paragraph, further comprising a wetting or dispersing agent, preferably wherein the wetting or dispersing agent comprises sodium lauryl sulfate. 20. The composition of any preceding clause, comprising a viscosity modifier selected from the group consisting of guar gum, gum arabic, xanthan gum, trehalose, and combinations thereof. 21. A method for deinking a substrate containing one or more ink compositions according to any one of items 1 to 20 that have been printed and dried on the substrate, the method comprising the step of immersing the printed substrate in a deinking solution containing alkaline water having a pH of 7.1 to 14.0, preferably 8.0 to 12.0, and more preferably 10.0 to 11.0. 22. The method of paragraph 21, wherein the pH of the deinking solution is maintained by the use of an organic amine selected from the group consisting of primary, secondary, and tertiary aliphatic amines. 23. The method of paragraph 22, wherein the organic amine is triethanolamine. 24. A method for preparing a printing ink composition according to any one of paragraphs 1 to 20, comprising the step of milling a dispersion comprising water and one or more keratin-based pigments. 25. A method for printing an image on a substrate, comprising the steps of applying a printing ink composition according to any one of items 1 to 20 onto the substrate and curing it. 26. The method of item 25, wherein the curing step is preferably heat curing at a temperature of 220°C or less. 27. The method of paragraph 25 or paragraph 26, wherein the printing is selected from inkjet printing, flexography, nozzle coating, slot coating, screen printing, lithography, offset printing, and gravure printing, preferably the printing is by inkjet printing. 28. The method of any one of items 25 to 27, wherein the substrate is selected from plastic, textile, paper, metal, glass, polymer film, and ceramic substrates, preferably, the substrate is selected from textile and paper. 29. A printed matter comprising or derived from the printing ink composition of any one of items 1 to 20, or prepared by the method of any one of items 25 to 28. 30. A method for deinking a substrate, comprising: i) applying and drying a printing ink composition according to any one of items 1 to 20 onto a substrate to provide a printing substrate; ii) immersing the printing substrate in a deinking solution containing alkaline water having a pH of 7.1 to 14.0, preferably 8.0 to 12.0, and more preferably 10.0 to 11.0; A method comprising:

[0059] Although the present invention has been described in detail, including various embodiments thereof, it will be appreciated that those skilled in the art, upon consideration of this disclosure, may make modifications and / or improvements to the present invention which are within the scope and spirit of the present invention. [Example]

[0060] The present invention is further described by the following non-limiting examples, which are intended to further illustrate the present invention and are not intended, nor should they be construed, to limit the scope of the invention.

[0061] Example 1 A dispersion of red keratin particles was prepared in a solution according to the following process.

[0062] [Table 1]

[0063] To a glass beaker equipped with a mechanical stirrer, 124.83 g of deionized water (conductivity less than 10 microsiemens) was added, followed by 2.0 g of sodium lauryl sulfate (dispersant); 0.27 g of Proxel GXL (antimicrobial); and 0.15 g of Airase 5355 (antifoaming agent). While the mixture was stirred, 23.0 g of WS Pigment Red (a keratin pigment having a particle size (Dv50) of 2,032 nm as measured by DLS) powder was added and further stirred for 60 minutes to wet the pigment particles. The resulting premix was then added to an Eiger 50 laboratory mill equipped with 0.8 mm ytterbium-zirconium oxide grinding media. The mill was started, and samples were periodically removed to measure particle size by DLS using a Malvern Zetasizer. After 20 minutes of grinding, the Dv50 was 574 nm. After 45 minutes of milling, the particle size had increased again to a Dv50 of 1,343 nm, and finally measured at 1,543 nm after 60 minutes of milling. The dispersions were measured for color strength compared to the premix. It was found that color strength increased in dispersions with smaller particle sizes. This is a very significant result, as it was found that the color strength of the final dispersion was significantly higher than the initial color strength of the premix (before milling). The results, shown in Table 2, further demonstrate that color strength increased with decreasing particle size.

[0064] Table 2 below shows that only 20 minutes of milling time was required to reduce the WS Pigment Red particles used in Example 1 to about 600 nm, and that a slightly longer milling time actually resulted in some increase in particle size. These data demonstrate that a highly energy-efficient milling process can be used in the present invention to provide a pigment with the required particle size. The increase in color intensity after only 20 minutes of milling was also quite surprising, increasing to more than 107% of the original intensity. Therefore, milling the particles results in a keratin-based pigment with increased color intensity.

[0065] [Table 2]

[0066] Further evidence of the increased color intensity of the milled dispersions was obtained by preparing drawdown samples on inkjet-coated paper using No. 6 Kbar. The premix gave a dull shade with some reasonable edge definition. The sample milled for 45 minutes showed a very noticeable increase in color intensity and perfect edge definition. It is hypothesized that the reason for this result is that milling the pigment particles (preferably to approximately 600 nm or less, although this effect is achieved by milling to approximately 1500 nm) causes a partial unwinding of the keratin helix structure, which exposes more coloring groups on the surface of the keratin.

[0067] [Table 3]

[0068] To a glass beaker equipped with a mechanical stirrer, 124.83 g of deionized water (conductivity less than 10 microsiemens) was added; then, 2.3 g of sodium lauryl sulfate (dispersant); 0.27 g of Proxel GXL (antimicrobial); and 0.15 g of Airase 5355 (antifoaming agent). While the mixture was stirred, 23.0 g of WS Pigment Red (a keratin pigment having a particle size (Dv50) of 2,032 nm as measured by DLS) powder was added and further stirred for 60 minutes to wet the pigment particles. The resulting premix was then added to an Eiger 50 laboratory mill equipped with 0.8 mm ytterbium-zirconium oxide grinding media. The mill was started, and samples were periodically removed to measure particle size by DLS using a Malvern Zetasizer. After 30 minutes of grinding, the Dv50 was 593 nm. The dispersion was measured for color strength compared to the premix. It was discovered that color intensity increased in dispersions with smaller particle sizes. This is a very significant result because it was discovered that the color intensity of the final dispersion was significantly higher than the initial color intensity of the premix (before milling). The results, shown in Table 4, further demonstrate that color intensity increased with decreasing particle size. The viscosity of the dispersion was measured using a Brookfield DVII+Pro equipped with a 00 spindle and found to be 5.13 cP at 32°C.

[0069] [Table 4]

[0070] This second example, using a milling time optimized for particle size, liberated particles with a Dv50 particle size of 593 nm, again demonstrating a significant increase in color intensity of the dispersion after milling.

[0071] [Table 5]

[0072] The following process was used to prepare a simple ink for subsequent evaluation by inkjet printing. To a separate 25 g sample of the dispersion from Example 2, 10 g of glycerin was added. The particle size of the charged material was measured by DLS at 593 nm. The mixture was stirred in a glass beaker using a magnetic stirrer for approximately 60 minutes, and then the physical properties of the ink were measured.

[0073] The viscosity of the ink was measured using a Brookfield DVII+Pro equipped with a 00 spindle and found to be 6.57 cP at 32°C and 6.08 cP at 35°C.

[0074] The resulting ink of Example 3 was then loaded into a Dimatix DMP print cartridge, and the printer was set up so that the print head temperature was 32°C and the print head angle was 2.5°. The print resolution was set to 1,700 DPI. A 2 cm x 2 cm print block was achieved in a single pass. The printed image on the Panama cotton showed very well-resolved edges, with good uniform color saturation across the printed color block and good wetting of the cotton fabric. Furthermore, the edges and corners of the square block were very well resolved, indicating good print quality.

[0075] The resulting print was then heat cured using a standard thermal heat press at 160°C for 2 minutes.

[0076] Films of the ink from Example 3 were also produced by drawdown, using a 24 micron ink film applied to PET, then transfer printed onto Panama cotton and dried for 5 minutes at 150° C. The ink coverage of the samples produced by such drawdown closely reproduces the same ink laydown as would be expected from inkjet printing.

[0077] The washfastness of the drawdown printed Panama cotton was tested as follows: Under very harsh test conditions, a 1% solution of standard laundry detergent (Persil, Unilever) was used to partially remove the pigment from the Panama cotton, giving it a washfastness rating of 2-3, where 4 is complete fixation and 1 is complete removal. This is an average rating for textile pigment inks. It should be noted that the inventive examples did not contain any additional optional binders.

[0078] The resolubility of the ink was measured using a standard method in which a film of the ink was cast onto a glass slide, allowed to air dry for at least one hour, and then immersed in either deionized water or a 1% solution of Tergitol 15-S-7 in deionized water. In both cases, the resolubility was assigned a rating of 4 by visual inspection. In this test, the dried ink was removed from the slide as small flakes that were still present as flakes in the wash solution after 60 minutes. In this context, perfect resolubility is a rating of 4, and no resolubility is a rating of 1. This resolubility test was developed to mimic what happens in an inkjet printhead if the ink is allowed to dry in air, and then the inkjet printhead can be permanently damaged if the dried ink is not resolubilizable. A resolubility rating of 4 indicates very good suitability for industrial textile printing.

[0079] Deinking was tested by soaking fabric (in this case, Panama cotton) in a basic solution at 60°C for two hours. Three basic solutions with pH values ​​ranging from 10 to 13 were tested. In all cases, easy deinking was observed. In particular, when pH values ​​of 10, 11.5, and 13.0 were used, deinking after two hours was given a rating of 4. Deinking is rated as 4 if the ink is completely removed and a new white surface is left (even if the ink has been bleached from the surface), and 1 if no ink is removed at all.

[0080] [Table 6]

[0081] As demonstrated by the results in Table 6, the inks of the present invention provide improved resolubility and deinking properties compared to the comparative inks.

Claims

1. 1. A printing ink composition comprising one or more keratin-based pigments and water, wherein said one or more keratin-based pigments have an average particle size of 3000 nm or less.

2. 10. The printing ink composition of claim 1, comprising one or more keratin-based pigments and water, wherein the one or more keratin-based pigments have an average particle size of 3000 nm or less, and the keratin-based pigments are milled.

3. 3. The composition of claim 1 or 2, wherein the one or more keratin-based pigments have an average particle size of 2000 nm or less, preferably 1000 nm or less, more preferably 600 nm or less.

4. 4. A composition according to any one of claims 1 to 3, comprising at least 30% (w / w) water, preferably at least 40% (w / w) water, more preferably at least 50% (w / w) water.

5. 5. A composition according to any one of claims 1 to 4, comprising from about 30% to about 90% (w / w) water, preferably from about 40% to about 80% (w / w) water, more preferably from about 50% to about 70% (w / w) water.

6. 6. The composition according to any one of claims 1 to 5, comprising at least 5% (w / w) of one or more keratin-based pigments, preferably at least 7% (w / w) of one or more keratin-based pigments, more preferably at least 9% (w / w) of one or more keratin-based pigments.

7. 7. The composition according to claim 1, comprising from about 5% to about 15% (w / w) of one or more keratin-based pigments, preferably from about 7% to about 12% (w / w) of one or more keratin-based pigments.

8. 8. The composition of any one of claims 1 to 7, further comprising one or more additional materials selected from the group consisting of water retention agents (solid or liquid), wetting agents, dispersing agents, surfactants, binders, viscosity modifiers, and preservatives.

9. 9. The composition of any one of claims 1 to 8, comprising an acid-functional binder selected from the group consisting of acrylics, polyurethanes, styrene-maleic acid, polycarbonates, styrene-maleic anhydride, and copolymers thereof.

10. The composition of claim 1 , wherein the acid-functional binder further comprises hydroxyl groups.

11. 9. The composition of any one of claims 1 to 8, comprising a polymeric binder selected from styrene maleic anhydride, styrene-maleic acid, acrylic resins, polyurethanes, polycarbonates, and copolymers thereof, in an amount of 5% (w / w) or less.

12. 12. The composition of any one of claims 1 to 11, having a bio-renewable carbon (BRC) content of 90% or more.

13. 13. The composition according to any one of claims 1 to 12, which is suitable for deposition using a method selected from inkjet printing, flexographic printing, nozzle coating, slot coating, screen printing, lithography, offset printing, and gravure printing, preferably suitable for deposition using inkjet printing.

14. The composition of claim 1 which is an inkjet ink.

15. 15. The composition of any one of claims 1 to 14, wherein the carrier liquid for the ink is water and a humectant derived from renewable sources.

16. 16. The composition of claim 15, wherein the humectant is selected from the group consisting of glycerol, ethylene glycol, diethylene glycol, monopropylene glycol, and combinations thereof, preferably the humectant is glycerol.

17. 17. The composition of claims 1 to 16, comprising a preservative derived from renewable sources.

18. 18. The composition of claim 17, wherein the preservative is selected from the group consisting of 2-phenoxyethanol and sodium benzoate.

19. 19. A composition according to any one of claims 1 to 18, comprising a wetting or dispersing agent, preferably wherein the wetting or dispersing agent comprises sodium lauryl sulphate.

20. 20. The composition of any one of claims 1 to 19, comprising a viscosity modifier selected from the group consisting of guar gum, gum arabic, xanthan gum, trehalose, and combinations thereof.

21. A method for deinking a substrate comprising the ink composition according to any one of claims 1 to 20 that has been printed and dried on the substrate, the method comprising the step of immersing the printed substrate in a deinking solution comprising alkaline water having a pH of 7.1 to 14.0, preferably 8.0 to 12.0, and more preferably 10.0 to 11.

0.

22. 22. The method of claim 21, wherein the pH of the deinking solution is maintained by the use of an organic amine selected from the group consisting of primary, secondary, and tertiary aliphatic amines.

23. 23. The method of claim 22, wherein the organic amine is triethanolamine.

24. 1. A method for producing a print ink composition comprising one or more keratin-based pigments and water, the method comprising the step of milling a dispersion comprising water and one or more keratin-based pigments, wherein the one or more keratin-based pigments have an average particle size of 3000 nm or less.

25. The method according to claim 24, wherein the ink composition is one according to any one of claims 2 to 20.

26. 26. The method according to claim 24 or 25, wherein the grinding step is carried out for up to 60 minutes, preferably up to 45 minutes.

27. A method of printing an image on a substrate, comprising applying a printing ink composition according to any one of claims 1 to 20 onto the substrate and curing.

28. 28. The method of claim 27, wherein the print ink composition is milled prior to application onto a substrate.

29. 29. The method according to claim 27 or 28, wherein the curing step is thermal curing, preferably at a temperature of 220°C or less.

30. 30. The method of claim 27, 28 or 29, wherein said printing is selected from inkjet printing, flexography, nozzle coating, slot coating, screen printing, lithography, offset printing and gravure printing, preferably said printing is by inkjet printing.

31. The method according to any one of claims 27 to 30, wherein the substrate is selected from plastic, textile, paper, metal, glass, polymer film, and ceramic substrates, preferably the substrate is selected from textile and paper.

32. A printed product comprising or derived from a printing ink composition according to any one of claims 1 to 20 or produced by a method according to any one of claims 27 to 31.

33. 1. A method for deinking a substrate, comprising: i) applying a printing ink composition according to any one of claims 1 to 20 onto a substrate and drying to provide a printed substrate; ii) immersing the printed substrate in a deinking solution comprising alkaline water having a pH of 7.1 to 14.0, preferably 8.0 to 12.0, more preferably 10.0 to 11.0; A method comprising:

34. 34. The method of claim 33, wherein the print ink composition is milled prior to application onto a substrate.

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