Deinkable ink with a 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 keratine-based pigment(s) and water. Advantageously, the ink according to the invention has superior color and lightfastness properties compared to inks based on traditional dyes. Further, substrates printed with the ink according to the invention can typically be deinked using a weakly alkaline pH aqueous solution, thereby enabling the substrate to be recycled and reused more readily. Thus, the printing ink composition according to the invention can improve sustainability, for example, in the packaging and textile industries.

Background Art

[0002] Dyeing and printing of substrates (e.g., textiles, paper, and plastics) using dye-based inks creates a printed substrate having a dye that is either covalently bonded to cellulose fibers (reactive direct dyes) in the case of cellulose-based substrates, or alternatively, strongly ionically bonded (acid dyes) in the case of substrates such as silk, synthetic nylon, and other substrates.

[0003] With the increasing market focus on sustainability and recycling, deinking 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. Further, the effluent may be heavily contaminated with environmentally harmful chemicals.

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

[0005] European Patent Application Publication No. 3,341,209 (Plastipak Packaging) relates to an ink composition for digital printing comprising an ink removal accelerating additive, specifically an ink removal accelerating additive having a Tg < 130°C in an amount of 5 to 20% w / w. An example of an ink removal accelerating additive is a styrene maleic anhydride (SMAN) binder having an acid value of 150 to 205 mg KOH / g. European Patent Application Publication No. 3,341,209 relates in detail to printing on recyclable articles of plastic and the use of a removal fluid having a pH of 12 to 13 at 70 to 90°C.

[0006] International Publication No. 2020 / 026161 (Wool Source) describes the application of keratin-derived pigments. The keratin-derived pigments described in International Publication No. 2020 / 026161 are not pulverized before use. International Publication No. 2020 / 026161 does not disclose the use of keratin-derived pigments for inkjet printing of substrates (e.g., textiles, paper, and plastics).

[0007] Any citation or identification of any document in this application does not constitute an endorsement that such document represents 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 [Overview of the project] [Means for solving the problem]

[0009] In a first embodiment, the present invention provides 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. Preferably, the one or more keratin-based pigments have an average particle size of 2000 nm or less, preferably 1000 nm or less, and more preferably 600 nm or less.

[0010] Preferably, the pigments based on one or more keratins have an average particle size of 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.

[0011] Unless otherwise specified, the terms “particle size” or “average particle size” as used herein refer to the volume distribution median particle diameter (the equivalent spherical diameter corresponding to 50% of the total particle volume, 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 appropriately measured by dynamic light scattering (DLS). Preferably, particle size is appropriately measured by dynamic light scattering (DLS) using a Malvern Zetasizer. Unless otherwise specified, particle size is appropriately measured by DLS in deionized water at 20°C.

[0012] In relation to this invention, "nanoscale" refers to particles having a single dimension less than 100 nm, which is the generally accepted definition of nanoparticles.

[0013] As will be understood by those skilled in the art, keratin-based pigments are 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, claws, talons, and hooves (e.g., from cows, goats, and 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. International Publication No. 2020 / 026161 discloses a method for preparing and staining keratin particles. International Publication No. 2020 / 026161 does not disclose grinding the stained 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, 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 inks based on traditional dyes.

[0016] The present invention also provides a method for preparing a printing 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 pigment present in the composition of the present invention is milled to obtain the desired particle size. Milling can be carried out using a suitable bead mill machine, for example, an Eiger laboratory bead mill (from Eiger Torrance Ltd.) equipped with a suitable milling medium. A suitable milling medium is a 0.8 mm ytterbium-zirconium oxide milling medium. Preferably, milling is carried out for a maximum of 60 minutes, more preferably a maximum of 45 minutes, more preferably a maximum of 30 minutes, and more preferably a maximum of 20 minutes. As used herein, "maximum" includes the endpoint, so "maximum" 60 minutes (for example) includes 60 minutes.

[0018] Preferably, the grinding 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, the grinding is carried out for 45 minutes, more preferably for 30 minutes, and even more preferably for 20 minutes.

[0020] Preferably, grinding is performed 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, grinding is performed 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] Printing ink compositions according to the present invention, comprising keratin-based pigments having the required particle size, have been found to be more lightfast and fade-resistant than corresponding inks containing conventional dyes. In addition, printing ink compositions according to the present invention, comprising 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 comprises alpha-keratin (α-keratin). As understood by those skilled in the art, alpha-keratin is a polypeptide chain that forms alpha-helices (α-helices). Two of these alpha-helices typically twist together to form a helical structure (often referred to as a coiled coil). Without wishing to be constrained in this regard, the inventors hypothesize that grinding keratin-based pigments to achieve the required particle size results in a partial unraveling of the keratin helix structure. In particular, it is hypothesized that grinding can break disulfide and other crosslinking bonds in the keratin structure, thus making the keratin more open and resulting in increased color intensity. In addition, the small particle size (i.e., 3000 nm or less) obtained by grinding keratin-based pigments means that the resulting ink composition is suitable for inkjet printing.

[0022] Preferably, the keratin-based pigments used in the present invention are pulverized before use. Preferably, the pulverized keratin-based pigments include keratin-based pigments in which the helical structure of keratin is partially unwound. Preferably, the pulverized keratin-based pigments include alpha-keratin in which the helical structure of alpha-keratin is partially unwound. Unless otherwise specified, a partially unwound helical structure means that some of the crosslinking bonds in the keratin helical structure are broken. For example, without wishing to be bound in this, the inventors hypothesize that pulverization breaks at least 5% of the crosslinking bonds 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 with a 00 spindle attached. More preferably, the printing ink composition of the present invention has a viscosity of 4 to 15 cP when measured at 32°C at 60 rpm using a Brookfield DVII+Pro viscometer with a 00 spindle attached.

[0024] Furthermore, the ink according to the present invention does not require the use of harsh chemical treatments, such as strong oxidizing agents or bleaching agents, such as sodium hypochlorite or hydrogen peroxide, and is removed more simply from the surface of substrates (especially fabrics and paper) than conventional dyes. Therefore, the inks according to the present invention are advantageous because they improve the recyclability of the printed substrates.

[0025] When attempting to remove reactive dyes covalently bonded to fabrics such as cotton or acidic dyes strongly ionically bonded to fabrics such as polyamide, harsh chemicals and often microbial treatments are often required in combination with bleaching agents. Even these severe oxidation or bleaching methods are almost impossible to remove sufficient trace amounts of dye from fabrics or other substrates. In the present invention, the inventors have addressed the problem of deinking by using a printing ink containing 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 capable of being deinked by a simple weakly alkaline pH aqueous solution (for example, an aqueous solution having a pH of 10 to 11 at approximately 25 to 65°C).

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

[0027] The printing ink according to the present invention may optionally contain one or more humectants in addition to water, that is, 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 contains glycerol. The typical amount of the humectant in the composition is from 0.5% by mass to 35% by mass, and preferably, the humectant is present at 5% by mass to 30% by mass.

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

[0029] Preferably, the printing ink according to the present invention may further contain a wetting agent or a dispersant, preferably a dispersant. Suitable dispersants include alkyl sulfonates, fatty sulfonates, and alkylaryl sulfonates. As is understood, fatty sulfonic acids are sulfonic acids having an aliphatic chain that is either saturated or unsaturated. Preferably, the dispersant is a dispersant based on coconut oil or palm oil, for example, 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 mass of the composition.

[0030] The printing ink according to the present invention may optionally further contain a viscosity modifier. Preferably, the viscosity modifier is 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 contain one or more antimicrobial agents (e.g., Proxel GXL) and / or one or more defoaming agents (e.g., Airase 5355). When used, the antimicrobial agent is typically present in an amount of 0.05% to 3% by mass. When used, the defoaming agent is typically present in an amount of 0.01% to 1.5% by mass.

[0032] Preferably, the printing ink according to the present invention is applied to a suitable substrate and then heated. During heating, the ink is fixed by curing at a maximum temperature of 220°C, depending on the temperature stability of the substrate, and there is no thermal degradation. In most cases, a significantly lower curing temperature is required. Preferably, the ink is cured at 50 to 220°C, more preferably at 80 to 190°C.

[0033] This ink can be cured on various plastics, textiles, paper (including cardboard and wallpaper), metals, glass, and other substrates, and exhibits excellent adhesion and abrasion resistance. The additional improved abrasion resistance is hypothesized to be due to keratin pigment particles, which, due to their hydrophobicity, actually rise to the surface of the coating during curing. This imparts a softer feel or "touch" to the surface of the printed substrate, and further 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. More preferably, the ink composition of the present invention is an inkjet printing ink.

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

[0036] As is understood in the art, the terms "deinking" or "deinking process" mean the removal of ink from a printed substrate.

[0037] Deinking can be easily achieved by immersing an object (i.e., a printed substrate) in an alkaline solution, preferably a weakly alkaline solution, such as triethanolamine in water with 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 further technical advantage of the present invention is the sustainability of the ink, including its exceptionally high bio-renewable carbon (BRC) content, which can be increased to over 90%. Furthermore, for substrates such as textiles and paper containing ink that is deinked after use in a convenient manner, the ink and its ability enable the textiles and paper to be recycled and reused. Both offer significant advantages, particularly in applications related to packaging and textiles, and sustainable and deinkable inks are not currently available.

[0039] European Patent Application Publication No. 3,341,209 (Plastipak Packaging) states that recyclable plastic articles coated with ink containing a base ink and additional ink removal-promoting additives can be deinked using a basic solution having a pH of 12–13 at a temperature range of 70–90°C. European Patent Application Publication No. 3,341,209 discloses that styrene-maleic anhydride copolymer can be used as an 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 European Patent Application No. 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 contains less than 5% (w / w) of a polymeric binder selected from styrene maleic anhydride, styrene-maleic acid, acrylic resin, polyurethane, polycarbonate, and copolymers thereof. More preferably, the ink contains substantially no polymeric binder selected from styrene maleic anhydride, styrene-maleic acid, acrylic resin, polyurethane, polycarbonate, and copolymers thereof (i.e., less than 1% (w / w)).

[0041] Preferably, the ink according to the present invention contains less than 5% (w / w) of an acid-functional polymer binder selected from acid-functional styrene-maleic anhydride, styrene-maleic acid, acrylic resin, polyurethane, polycarbonate, and copolymers thereof. More preferably, the ink contains substantially no acid-functional polymer binder selected from acid-functional styrene-maleic anhydride, styrene-maleic acid, acrylic resin, polyurethane, polycarbonate, and copolymers thereof (i.e., less than 1% (w / w)).

[0042] The inks of the present invention may contain low levels (i.e., less than 5% (w / w)) of carboxylic acid or sulfonic acid-functional binders that can be chemically covalently bonded to various textile fabrics and, additionally, to keratin pigment particles. Accordingly, the inks of the present invention may contain less than 5% (w / w) of carboxylic acid or sulfonic acid-functional polymer 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 may contain substantially no carboxylic acid or sulfonic acid-functional polymer binders selected from carboxylic acid or sulfonic acid-functional styrene-maleic anhydride, styrene-maleic acid, acrylic resins, polyurethanes, polycarbonates, and copolymers thereof (i.e., less than 1% (w / w)).

[0043] Alternatively, the ink may contain a binder, which is an optional component, to promote excellent fixation to the substrate. When the optional binder is selected for keratin-based pigment particles, these may be from a large number of different groups, including acid-functional and optionally and additionally hydroxyl-functional styrene-maleic anhydride, styrene-maleic copolymer, acrylic polymer, polyurethane, polycarbonate, and various available copolymers thereof. However, the optional binder (and any dispersants present) is preferably derived from natural sources in order to maintain a high (preferably 85% or more) bio-renewable carbon (BRC) content in the ink.

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

[0045] Under normal working conditions, for example, when printed and fixed using inkjet printing followed by heat press fixing at 160°C for 2 minutes, the pigment was found to bond well to a wide variety of woven fabrics, including cotton and polyester. In fact, even immersion in standard cleaning solutions did not allow for the removal of the pigment.

[0046] The use of keratin-based pigments in the inks of the present invention is advantageous because the dyes can bond to a variety of different substrates to which 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 then break down during alkaline hydrolysis, allowing not only the substrate to be recycled, but also the dyes and keratin particles to be recycled.

[0047] The ink compositions according to the present invention can be printed on a variety of different substrates. Examples of suitable substrates for which the present invention applies include, in particular, 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] Particularly suitable substrates for the present invention are preferably woven fabrics and paper substrates, and more preferably woven fabric substrates.

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

[0050] As is understood in the art, textiles are formed by weaving, knitting, crocheting, tying, tatting, felting, bonding, and / or frading yarn, and the yarn itself is formed from fibers. Suitable textile bases 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, linden (e.g., cashmere wool or merino wool), modal, muslin, organza, satin, spandex, suede, taffeta, toile, tweed, twill fabric, velvet, linen, ramie, sisal, bamboo, flax and combinations thereof. More preferably, suitable bases for use in the present invention can be selected from cotton, polyester and combinations thereof.

[0051] As used herein, the textile base material does not include paper.

[0052] The inks in the present invention are preferably composed mainly of bio-renewable carbon (BRC)-containing raw materials, so that even the colorants consist of approximately 90% bio-renewable carbon. Unless otherwise specified, the BRC content is determined in accordance with 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 dispersant preferably based on coconut oil or palm oil, such as a keratin-derived pigment having a BRC content of 90% or more and 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 can then be led to an ink with a high BRC content (preferably an ink with a BRC content of 85% or more, more preferably 90% or more) through careful selection of ink components. Preferably, the inks according to the present invention have a BRC content of 90% or more.

[0053] The inks according to the present invention are preferably highly resoluble, which is important for inkjet deposition methods. Resoluble is particularly important in inkjet printing because when the printing press is not in use, the ink dries in the surrounding air, which can cause solid deposits to form on the inkjet nozzles. The ability of these solid particles to redissolve (or be cleaned using a simple maintenance wipe) when the printing press is started is called resoluble. The inks in the present invention have been found to have exceptionally high resoluble properties, far superior to inks from comparative examples using standard textile pigment inks. Furthermore, the inks in the present invention have been found to impart a soft and protective feel or texture to the treated object and to be highly resistant to cracking. Cured films obtained from the inks according to the present invention preferably have improved abrasion and scratch resistance compared to those using ordinary organic pigments, and furthermore, the lightfastness of printed films containing keratin-derived pigments is better than that for the corresponding dyes alone.

[0054] It was discovered that woven fabrics treated with inks containing keratin-based pigments exhibited superior fastness compared to woven fabrics printed using only the corresponding dye inks. Furthermore, while dye-only inks could not be deinked under the aforementioned weakly basic aqueous conditions, the inks of the present invention were easily deinked under the same conditions.

[0055] The keratin-based pigment particles used in the ink of the present invention have a "sponge-like" property and are highly compressible, especially when deposited using an inkjet printhead, particularly with respect to the shear force applied to the ink. In fact, inks containing such pigment particles have been found to be inherently self-cleaning, and the print nozzles remained free of debris or deposits during printing tests. Furthermore, the compressibility of the keratin pigment particles in an inkjet printhead means that particles larger than the typical perceived size of organic pigments alone, approximately 101–150 nm, can be printed using the inkjet method.

[0056] Unless otherwise specified, pH was measured at 25°C using an Oakton 510 series pH meter. [Modes for carrying out the invention]

[0057] The present invention is further illustrated by the following series of numbered paragraphs and combinations arising from the dependencies and backreferences shown. In particular, in each example in which a range of paragraphs is described, in relation to terms such as, for example, "the method of any one of paragraphs 1 to 5," it is meant that all paragraphs within that range are obviously disclosed to those skilled in the art, that is, the wording of this term should be understood by those skilled in the art as synonymous with "the method of any one of paragraphs 1, 2, 3, 4 and 5." Furthermore, it is obviously noted that the following series of numbered paragraphs represent appropriately structured portions of the description directed toward 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. 2.1 A composition according to item 1, wherein the pigments based on one or more types of keratin have an average particle size of 2000 nm or less, preferably 1000 nm or less, and more preferably 600 nm or less. 3. The composition of item 1 or item 2, comprising at least 30% (w / w) of water, preferably at least 40% (w / w) of water, and more preferably at least 50% (w / w) of water. 4. The composition of any preceding item, comprising about 30% to about 90% (w / w) of water, preferably about 40% to about 80% (w / w) of water, and more preferably about 50% to about 70% (w / w) of water. 5. Any composition of the preceding item 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, and more preferably at least 9% (w / w) of one or more keratin-based pigments. 6. Any composition of the preceding item comprising approximately 5% to approximately 15% (w / w) of one or more keratin-based pigments, preferably approximately 7% to approximately 12% (w / w) of one or more keratin-based pigments. 7. Any composition of a preceding item, further comprising one or more additional materials selected from the group consisting of water-retaining agents (solid or liquid), wetting agents, dispersants, surfactants, binders, viscosity modifiers, and preservatives. 8. Any composition of a preceding item comprising an acid-functional binder selected from the group consisting of acrylic resin, polyurethane, styrene-maleic acid, polycarbonate, styrene-maleic anhydride, and copolymers thereof. 9. Any composition of the preceding item, wherein the acid-functionalized binder further comprises a hydroxyl group. 10. A composition according to any one of items 1 to 7, comprising 5% (w / w) or less of a polymeric binder selected from styrene maleic anhydride, styrene-maleic acid, acrylic resin, polyurethane, polycarbonate and its copolymers. 11. Any composition according to any preceding item, having a bio-renewable carbon (BRC) content of 90% or more. 12. The composition of item 8 or 9, wherein the pigment-to-binder ratio is in the range of 1:50 to 50:1 pigment particles:binder. 13. Any composition of the preceding item that 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, and preferably suitable for deposition using inkjet printing. 14. A composition of any of the preceding items, which is an inkjet ink. 15. A composition of any preceding item wherein the carrier liquid for the ink is water and a water-retaining agent derived from a renewable source. 16. The composition of item 15, wherein the water-retaining agent is selected from the group consisting of glycerol, ethylene glycol, diethylene glycol, monopropylene glycol, and combinations thereof, and preferably the water-retaining agent is glycerol. 17. A composition according to any preceding item, comprising a preservative derived from a renewable source. 18. The composition of item 17, wherein the preservative is selected from the group consisting of 2-phenoxyethanol and sodium benzoate. 19. A composition of any preceding item comprising a wetting agent or a dispersant, preferably the wetting agent or dispersant comprising sodium lauryl sulfate. 20. Any composition of a preceding item 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 from items 1 to 20 that have been printed and dried on the substrate, comprising the step of immersing the printed substrate in a deinking solution containing alkaline water with a pH of 7.1 to 14.0, preferably 8.0 to 12.0, more preferably 10.0 to 11.0. 22. The method of item 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 item 22, wherein the organic amine is triethanolamine. 24. A method for preparing a printing ink composition according to any of items 1 to 20, comprising the step of grinding a dispersion containing 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 thermal curing at a temperature of 220°C or lower. 27. The method of item 25 or 26, wherein the printing is selected from inkjet printing, flexographic printing, nozzle coating, slot coating, screen printing, lithography, offset printing, and gravure printing, and preferably the printing is by inkjet printing. 28. Any method of items 25 to 27, wherein the substrate is selected from plastic, textile, paper, metal, glass, polymer film and ceramic substrate, preferably the substrate is selected from textile and paper. 29. Printed material comprising or derived from any of the printing ink compositions of items 1 to 20, or prepared by any of the methods of items 25 to 28. 30. A method for deinking a substrate, i) A step of applying a printing ink composition according to any of items 1 to 20 onto a substrate and drying it to provide a printing substrate, ii) A step of immersing the printing substrate in a deinking solution containing alkaline water with a pH of 7.1 to 14.0, preferably 8.0 to 12.0, more preferably 10.0 to 11.0. Methods that include...

[0059] The present invention is described in detail, including various embodiments thereof. However, those skilled in the art will understand that modifications and / or improvements to the present invention can be made in consideration of this disclosure, and such modifications and improvements will fall within the scope and spirit of the invention. [Examples]

[0060] The present invention can be further illustrated by the following non-limiting embodiments, which are intended to further illustrate the invention and are not intended to limit the scope of the invention, nor should they be construed as limiting it.

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

[0062] [Table 1]

[0063] In 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 agent), and 0.15 g of Airase 5355 (defoamer). While stirring the mixture, 23.0 g of WS Pigment Red powder (keratin pigment with a particle size of 2,032 nm (Dv50) as measured by DLS) was added, and the mixture was further stirred for 60 minutes to wet the pigment particles. The resulting premix was then added to an Eiger 50 laboratory mill equipped with a 0.8 mm ytterbium-zirconium oxide grinding medium. The mill was started, and samples were periodically removed and their particle size was measured by DLS using a Malvern Zetasizer. After 20 minutes of grinding, the Dv50 was 574 nm. After 45 minutes of grinding, the particle size had increased again to 1,343 nm (Dv50), and finally, after 60 minutes of grinding, it was measured at 1,543 nm. The dispersions were measured in terms of color intensity compared to the premix. It was found that the color intensity increased in dispersions with smaller particle sizes. This is a very important result because the color intensity of the final dispersion was found to be significantly higher than the initial color intensity of the premix (before grinding). The results shown in Table 2 further demonstrate that the color intensity increased with decreasing particle size.

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

[0065] [Table 2]

[0066] Further evidence of increased color intensity in the ground dispersion was obtained by preparing drawdown samples on inkjet-coated paper using No. 6 Kbar. The premix gave dull shading with some reasonable edge clarity. Samples ground for 45 minutes showed a very remarkable increase in color intensity and perfect edge clarity. The reason for this result is hypothesized to be that grinding the pigment particles (the effect is achieved by grinding to approximately 1500 nm, but preferably to approximately 600 nm or less) results in a partial unraveling of the keratin helix structure, which exposes more color groups to the surface of the keratin.

[0067] [Table 3]

[0068] In 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 agent); and 0.15 g of Airase 5355 (defoamer) were added. While stirring the mixture, 23.0 g of WS Pigment Red powder (keratin pigment with a particle size of 2,032 nm (Dv50) as measured by DLS) was added, and the mixture was further stirred for 60 minutes to wet the pigment particles. The resulting premix was then added to an Eiger 50 laboratory mill equipped with a 0.8 mm ytterbium-zirconium oxide grinding medium. The mill was started, and samples were periodically removed and their particle size was measured by DLS using a Malvern Zetasizer. After 30 minutes of grinding, the Dv50 was 593 nm. The dispersion was measured for color intensity compared to the premix. It was found that color intensity increased in dispersions with smaller particle sizes. This is a very important result because the color intensity of the final dispersion was found to be significantly higher than the initial color intensity of the premix (before grinding). 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 with a 00 spindle and was found to be 5.13 cP at 32°C.

[0069] [Table 4]

[0070] This second embodiment, employing an optimized grinding time for particle size, releases particles with a Dv50 particle size of 593 nm, again demonstrating a significant increase in the color intensity of the dispersion after grinding.

[0071] [Table 5]

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

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

[0074] The resulting ink from Example 3 was then filled into a Dimatix DMP print cartridge, and the printer was set to a printhead temperature of 32°C and a printhead angle of 2.5°. The print resolution was set to 1,700 DPI. A 2cm x 2cm print block was achieved in a single pass. The printed image on Panama cotton showed very well-resolved edges, along with good uniform color saturation across the printed color blocks and good weave 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 heat press at 160°C for 2 minutes.

[0076] Using a 24-micron ink film applied to PET, an ink film from Example 3 was also manufactured by drawdown, then transferred onto Panama cotton and dried at 150°C for 5 minutes. The ink coating of the sample produced by this drawdown accurately reproduces the same ink laydown expected from inkjet printing.

[0077] The washability of 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 washability rating of 2-3, where 4 is complete fixation and 1 is complete removal. This is the average rating for textile pigment inks. It should be noted that the embodiments of the present invention did not contain any additional optional binders.

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

[0079] Deinking was tested by immersing the fabric (in this case, Panama cotton) in a basic solution at 60°C for 2 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 2 hours was given a rating of 4. Deinking was rated 4 if it was completely removed and a new white surface remained (even if the ink was bleached from the surface), and rated 1 if no ink was removed at all.

[0080] [Table 6]

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

Claims

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, the average particle size being the volume distribution median particle diameter (Dv50) measured by dynamic light scattering, and the keratin-based pigments are pulverized.

2. The composition according to claim 1, wherein one or more keratin-based pigments have an average particle size of 2000 nm or less.

3. The composition according to claim 2, wherein one or more keratin-based pigments have an average particle size of 1000 nm or less.

4. The composition according to claim 3, wherein one or more keratin-based pigments have an average particle size of 600 nm or less.

5. The composition according to claim 1, comprising at least 30% (w / w) water.

6. The composition according to claim 5, comprising at least 40% (w / w) water.

7. The composition according to claim 6, comprising at least 50% (w / w) water.

8. The composition according to claim 1, comprising 30% to 90% (w / w) water.

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

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

11. The composition according to claim 1, further comprising one or more additional materials selected from the group consisting of water-retaining agents (solid or liquid), wetting agents, dispersants, surfactants, binders, viscosity modifiers, and preservatives.

12. The composition according to claim 1, comprising an acid-functional binder selected from the group consisting of acrylic resin, polyurethane, styrene-maleic acid, polycarbonate, styrene-maleic anhydride, and copolymers thereof.

13. The composition according to claim 12, wherein the acid-functional binder further comprises a hydroxyl group.

14. The composition according to claim 1, comprising 5% (w / w) or less of a polymeric binder selected from styrene maleic anhydride, styrene-maleic acid, acrylic resin, polyurethane, polycarbonate, and copolymers thereof.

15. The composition according to claim 1, wherein the bio-renewable carbon (BRC) content is 90% or more.

16. The composition according to claim 1, suitable for deposition using a method selected from inkjet printing, flexographic printing, nozzle coating, slot coating, screen printing, lithography, offset printing, and gravure printing.

17. The composition according to claim 16, which is suitable for deposition using inkjet printing.

18. The composition according to claim 1, which is an inkjet ink.

19. The composition according to claim 1, wherein the carrier liquid for the ink is water and a water-retaining agent derived from a renewable source.

20. The composition according to claim 19, wherein the water-retaining agent is selected from the group consisting of glycerol, ethylene glycol, diethylene glycol, monopropylene glycol, and combinations thereof.

21. The composition according to claim 11, comprising a preservative derived from a renewable source.

22. The composition according to claim 21, wherein the preservative is selected from the group consisting of 2-phenoxyethanol and sodium benzoate.

23. The composition according to claim 11, comprising a wetting agent or a dispersing agent.

24. The composition according to claim 23, wherein the wetting agent or dispersant comprises sodium lauryl sulfate.

25. The composition according to claim 11, comprising a viscosity modifier selected from the group consisting of guar gum, gum arabic, xanthan gum, trehalose, and combinations thereof.

26. A method for deinking a substrate containing an ink composition according to any one of claims 1 to 25, which has been printed on the substrate and dried, comprising the step of immersing the printed substrate in a deinking solution containing alkaline water with a pH of 7.1 to 14.

0.

27. ​​The method according to claim 26, further comprising the step of immersing a printed substrate in a deinking solution containing alkaline water with a pH of 8.0 to 12.

0.

28. The method according to claim 27, further comprising the step of immersing a printed substrate in a deinking solution containing alkaline water with a pH of 10.0 to 11.

0.

29. The method according to claim 26, 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.

30. The method according to claim 29, wherein the organic amine is triethanolamine.

31. A method for producing a printing ink composition comprising one or more keratin-based pigments and water, comprising the step of grinding 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, and the average particle size is the volume distribution median particle diameter (Dv50) measured by dynamic light scattering.

32. The method according to claim 31, wherein the ink composition is one of the claims 1 to 25.

33. The method according to claim 31, wherein the grinding process is carried out for a maximum of 60 minutes.

34. The method according to claim 33, wherein the grinding process is carried out for a maximum of 45 minutes.

35. A method for printing an image on a substrate, comprising the steps of applying a printing ink composition according to any one of claims 1 to 25 to the substrate, and curing it.

36. The method according to claim 35, wherein the printing ink composition is pulverized before being applied to a substrate.

37. The method according to claim 35, wherein the curing step is thermal curing.

38. The method according to claim 35, wherein the printing is selected from inkjet printing, flexographic printing, nozzle coating, slot coating, screen printing, lithography, offset printing, and gravure printing.

39. The method according to claim 38, wherein the printing is performed by inkjet printing.

40. The method according to claim 35, wherein the substrate is selected from plastic, textile, paper, metal, glass, polymer film, and ceramic substrate.

41. The method according to claim 40, wherein the base material is selected from textiles and paper.

42. A printed article comprising or derived from the printing ink composition described in any one of claims 1 to 25.

43. A method for deinking a substrate, i) A step of applying and drying a printing ink composition according to any one of claims 1 to 25 onto a substrate to obtain a printed substrate, ii) A step of immersing the printed substrate in a deinking solution containing alkaline water with a pH of 7.1 to 14.

0. A method that includes this.

44. The method according to claim 43, wherein the printed substrate is immersed in a deinking solution containing alkaline water with a pH of 8.0 to 12.

0.

45. The method according to claim 44, wherein the printed substrate is immersed in a deinking solution containing alkaline water with a pH of 10.0 to 11.

0.

46. The method according to claim 43, wherein the printing ink composition is pulverized before being applied to a substrate.

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