Waterborne polyurethane resin dispersion

Abstract

A waterborne polyurethane resin dispersion, the polyurethane resin can be obtained by reacting an allophanate-based isocyanate according to general formula I or II, optionally a polyether diol, a polyol containing a quaternary N-atom or a tertiary amino group, and a polyol selected from polyester polyols, polyether polyols, polycarbonate polyols, polyacrylate polyols, polyolefins and polyamide polyols. The polyurethane resin is suitable as a resin in a processing liquid for a substrate and an image prepared by inkjet printing. General formula I General formula II

Description

Technical Field

[0001] The present invention relates to an aqueous polyurethane resin dispersion, and more particularly to the use of a polyurethane resin in a treatment liquid for a substrate or a treatment liquid for printing an image by inkjet printing using an aqueous inkjet ink. Background Art

[0002] In recent years, inkjet technology has been increasingly used for industrial printing applications such as displays, posters, billboards, packaging, textiles, etc. In such applications, durability such as lightfastness, waterfastness, and abrasion resistance are important requirements for printed images, and therefore pigment-based inks have been developed.

[0003] Inks such as solvent-based inkjet inks using an organic solvent as a vehicle, and ultraviolet curable inkjet inks including a polymerizable monomer as a main component have been widely used in industrial applications.

[0004] However, solvent-based inkjet inks are not environmentally preferred because the solvent evaporates in the atmosphere. UV curable inkjet inks have limited application areas because they may have skin sensitizing properties depending on the monomers used and require expensive UV irradiation equipment to be incorporated on the printer body.

[0005] In view of this background, pigment-based aqueous inks for inkjet recording have been developed that can be directly used for printing on porous and non-porous substrates and have a small environmental load.

[0006] However, compared with UV technology, it is still difficult for water-based resin-based inks to adhere directly to non-porous substrates or substrates showing low absorption.

[0007] WO2019 / 105786 teaches a primer solution comprising an aqueous polyurethane resin having cationic groups and polyalkylene oxides in its side chains. The resin achieves improved adhesion to non-porous substrates, and the cationic groups ensure the color fixation of the colorant contained in the aqueous inkjet ink and sprayed onto the primer liquid. However, these primers still suffer from insufficient color fixation and adhesion to non-porous substrates or substrates with low absorbency.

[0008] US2009 / 0233065 discloses an inkjet pretreatment liquid containing cationic polyurethane. The cationic polyurethane is obtained by using a chain extender having a tertiary amino group, thereby introducing a cationic group into the main chain of the resin. The resin ensures good adhesion between the resin and the non-porous substrate. The storage stability of the pretreatment liquid containing cationic polyurethane still needs to be improved.

[0009] US2008 / 0090949 discloses a kind of inkjet receptor that comprises cationic polyurethane resin aqueous dispersion.Compare with the polyol with primary OH-group, the polyol that contains tertiary amino group with secondary OH-group, which is used in the preparation of resin, will have limited reactivity.Limited reactivity will limit the length of polymer chain, and therefore reduces the favorable physical properties of resin, such as adhesion, scratch resistance and mechanical property.In addition, as the preparation method of disclosed cationic polyurethane in US2008 / 0090949 is laborious, because at first need to prepare the polyol that contains tertiary amino group in advance.

[0010] As described above, it is highly desirable to develop a substrate treatment fluid for inkjet printing using aqueous pigment inks which exhibits improved fixing properties, results in excellent print quality (increased color saturation, reduced coalescence and bleeding) and provides printed images that exhibit excellent physical properties (such as flexibility and adhesion to the substrate) and can be produced via an efficient synthesis process. Summary of the invention

[0011] It is an object of the present invention to provide a solution to the above mentioned problems. This object is achieved by incorporating the polyurethane resin dispersion defined in the present disclosure into an aqueous treatment fluid.

[0012] According to another aspect, the present invention includes an aqueous treatment fluid according to the present disclosure, wherein a polyurethane resin is included as a binder.

[0013] According to another aspect, the present invention comprises an inkjet recording method using a polyurethane resin as defined in the present disclosure. The method is defined in the present disclosure.

[0014] Other features, elements, steps, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention. Specific embodiments of the present invention are also defined in the present disclosure. DETAILED DESCRIPTION

[0015] A. Waterborne polyurethane resin dispersion

[0016] The aqueous polyurethane resin dispersion of the present invention is characterized in that the resin comprises units derived from isocyanates, tertiary amino groups or quaternary N-atoms based on allophanate and units derived from polymer polyols selected from the group consisting of polyester polyols, polyether polyols, polycarbonate polyols, polyolefin polyols, polyacrylate polyols and polyamide polyols. Optionally, polyethers are present in the side chains of the polyurethane backbone. Preferably, the tertiary amino groups are protonated so that cationic groups are present in the resin. Both the cationic groups and the polyethers in the side chains increase the dispersibility and colloidal stability of the resin in water. The polyester urethane resin of the present invention can preferably be obtained by reacting isocyanates based on allophanate with polyester polyols, polyether glycols, tertiary amino groups or quaternary N-atoms containing aromatic moieties.

[0017] A.1. Allophanate-based isocyanates

[0018] The PU resin dispersions according to the invention are obtainable by reacting an allophanate-based isocyanate according to the general formula I or II, optionally a polyether diol, a polyol containing a quaternary N-atom or a tertiary amino group, and a polyol selected from the group consisting of polyester polyols, polyether polyols, polycarbonate polyols, polyacrylate polyols, polyolefin polyols and polyamide polyols.

[0019] Allophanate-based isocyanates are formed by reaction of di- or polyisocyanates with alcohols (ROH) according to the following reaction:

[0020]

[0021] in:

[0022] D represents a linking group having at least 5 carbon atoms

[0023] R is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alicyclic group, a substituted or unsubstituted alkylaryl group, a substituted or unsubstituted aryl group or a heteroaryl group.

[0024] If a mixture of 2 different isocyanates is used in the above reaction, heteroallophanates are obtained, where D1≠D2:

[0025]

[0026] in:

[0027] D1 and D2 each independently represent a linking group having at least 5 carbon atoms

[0028] R represents the same group as above.

[0029] Preferably, D, D1 and D2 are independently represented by the following general formula III, IV, V or VI.

[0030]

[0031] Formula III

[0032]

[0033] Where the dashed line represents the connection to the N-atom in the general formulae I and II and n is an integer from 5 to 11, for n=5 pentane-1,5-diisocyanate (eg STABiO PDI from Mitsui) and for n=6 hexamethylene diisocyanate (Desmodur H from Covestro) can be used.

[0034] Examples of suitable linking groups are shown below, where the position of the linking group bonded to the nitrogen atom in Formulas I and II is shown in the structure by a dotted line. Preferred linking groups are derived from isophorone diisocyanate (IPDI) corresponding to Formula III, 4,4'-dicyclohexylmethane diisocyanate (H12MDI) corresponding to Formula IV, 2,4,4'-trimethyl-1,6-hexamethylene diisocyanate (TMDI) corresponding to Formula V, and hexamethylene diisocyanate (HMDI) corresponding to Formula VI with n=6 or pentamethylene diisocyanate (PDI) corresponding to Formula VI with n=5.

[0035] R—OH is preferably an alcohol, such as n-butanol, n-propanol, 2-ethylhexanol, n-octanol, 2-methylpropanol, 2-hydroxyethyl methacrylate, 2-hydroxyethyl acrylate, lauryl alcohol, coconut oil alkyl alcohol, stearyl alcohol, tridecanol, isotridecanol, cetyl alcohol, 1-eicosyl alcohol, isopropanol and C12-, C16-, C18-, C20-, C24-, C28- or C32-Guerbet alcohols.

[0036] Other preferred allophanate-based isocyanates are isocyanates containing a linking group D1, D2 or D being a cycloaliphatic ring, such as derived from IPDI or H12MDI.

[0037] Examples of suitable allophanate-based isocyanates are: the partially bio-based allophanate Tolonate X FLO100 based on HDI produced by Vencorex Chemicals, France (CAS Reg. No. 1628596-20-2) and the allophanate Desmodur XP 2565 based on IPDI and butan-1-ol, pentan-1-ol and 2-ethylhexan-1-ol produced by Covestro, Germany (CAS Reg. No. 1108168-72-4). The main structures present in Desmodur XP 2565 are according to formula VII, VIII and IX:

[0038]

[0039]

[0040] Other preferred allophanate structures are: (6-isocyanatohexyl) [[(6-isocyanatohexyl) amino] carbonyl] -, hexyl carbamate (CAS registration number 455258-01-2), N-(6-isocyanatohexyl)-N-[[(6-isocyanatohexyl) amino] carbonyl] -, 2-ethylhexyl carbamate (CAS registration number 455258-02-3), N-(6-isocyanatohexyl)-N-[[(6-isocyanatohexyl) amino] carbonyl] -, butyl carbamate (CAS registration number 215853-93-3), N-(6-isocyanatohexyl)-N-[[(6-isocyanatohexyl) amino] carbonyl] -, and 2-methylpropyl carbamate (CAS registration number 1642128-21-9).

[0041] Allophanates based on HDI and MDI are quite reactive, and are not as preferred as allophanates based on IPDI, for example. Desmodur XP 2860 available from Covestro, Germany is a kind of allophanate based on HDI (mixture of C3 / C4 / C5 allophanates). An example of allophanate based on MDI is Mondur MA-2300 and Mondur MA-2902 available from Covestro, Germany. The reactivity of allophanate can also be controlled by using a mixture of different allophanates. For example, allophanates based on IPDI such as Desmodur XP 2565 are mixed with Desmodur XP 2860. In some PU synthesis reactions, using Desmodur XP 2860 can cause viscosity to be too high, and mixing with XP 2565, which is less reactive, can provide advantages, and has better applicability in dispersion preparation.

[0042] Other preferred allophanate-based isocyanates are reactive allophanate structures, such as alkoxysilane-modified allophanate structures as described in European Patent Application EP 3 263 618 A1.

[0043] A.2. Polyols containing tertiary amino groups and / or quaternary N-atoms

[0044] Examples of cationic groups in the polyurethane resin of the present invention may be selected from protonated amines, heteroaromatic compounds containing protonated nitrogen, quaternized tertiary amines, N-quaternized heteroaromatic compounds, with quaternized tertiary amines and N-quaternized heteroaromatic compounds being more preferred.

[0045] In one embodiment of the invention, polyols are used which contain tertiary amino groups, ie precursors for obtaining cationic groups after protonation using an acid such as acetic acid.

[0046] Preferably, the polyol is a diol, which can react with an allophanate-based isocyanate to obtain the urethane bond of the prepared polyurethane resin, and which contains a tertiary amine group or a quaternary N-atom. The tertiary amino group or the quaternary N-atom can be present in the main chain or the side chain of the prepared polyurethane resin. In the first case, the tertiary amine group or the quaternary N-atom is present between the two reactive OH-groups of the diol. In the second case, the tertiary amine group or the quaternary N-atom is present as a side group on the carbon chain between the two reactive OH-groups of the diol. The reactive OH-group is a group that can react with polyisocyanates.

[0047] After preparing the polyurethane in a solvent such as acetone, acetonitrile or MEK, the tertiary amino group can be converted into a quaternary ammonium group by protonation with an acid such as acetic acid. Water is then added during high shear treatment or stirring to obtain an aqueous dispersion. The organic solvent (e.g. acetone) is then removed by reduced pressure distillation.

[0048] Examples of suitable diols having tertiary amino groups or N-atoms in the main chain for introducing cationic groups into the resin are: N-methyldiethanolamine (e.g. Genocur MDEA available via Rahn AG): CAS Reg. No. 105-59-9, 2-[(2-hydroxyethyl)phenylamino]ethanol: CAS Reg. No. 120-07-0, 2-[ethyl(2-hydroxyethyl)amino]ethanol: CAS Reg. No. 139-87-7, 2,2'-(butylimino)diethanol: CAS Reg. No. 102-79-4, diethanol-m-toluidine: CAS Reg. No. 91-99-6, N,N-dihydroxyethyl-p-toluidine (DHEPT available via Saltigo): CAS Reg. No. 3077-12-1.

[0049] Examples of suitable diols having a tertiary group or N-atom in the side chain for introducing cationic groups into the resin are: 2-[(dimethylamino)methyl]-1,3-propanediol: CAS Registry No. 69040-18-2, 2-methyl-2-dimethylaminomethyl-1,3-propanediol: CAS Registry No. 36254-31-6, 2-ethyl-2-dimethylaminomethyl-1,3-propanediol: CAS Registry No. 25941-41-7, 2-diethylaminoethyl-2-methyl-1,3-propanediol: CAS Registry No. 29006-31-3, 2-diethylaminomethyl-2-ethyl-1,3-propanediol: CAS Registry No. 26102-95-4, 3-[methyl(phenylmethyl)amino]-1,2-propanediol: CAS Registry No. 60278-98-0. The diol having an N-atom in the side chain has the advantage of further improving the colloidal stability of the resulting polyurethane resin relative to the diol having an N-atom in the main chain.

[0050] When using diols containing tertiary amino groups, the amino group is converted into a cationic group by protonation using an inorganic or organic acid. Examples of inorganic acids are hydrochloric acid, perchloric acid, sulfuric acid, hydrobromic acid, hydroiodic acid, phosphoric acid, nitric acid, boric acid, etc. Examples of organic acids include: acetic acid, formic acid, propionic acid, citric acid, oxalic acid, ascorbic acid, lactic acid, benzoic acid, toluenesulfonic acid, phenol, salicylic acid, acrylic acid, maleic acid, itaconic acid, stearic acid, glutamic acid, sulfoethyl methacrylate, carboxyethyl acrylate, or other organic compounds with acidic protons such as sulfonamides or mercaptans.

[0051] Examples of diols with quaternary N-atoms are: N,N-dimethyldiethanolamine with different counterions = CAS Reg. No. 44798-79-0, for example bis(2-hydroxyethyl)dimethylammonium methanesulfonate = CAS Reg. No. 152390-17-5, N-methyl-N-benzyl-N,N-di(hydroxyethyl)ammonium chloride = CAS Reg. No. 21056-86-0, N,N-bis(2-hydroxyethyl)-N-methyl-benzylammonium bromide (1:1) = CAS Reg. No. 1254832-90-0, benzoxanium chloride = CAS Reg. No. 19379-90-9, N,N-bis(2-hydroxyethyl)-N -Methyl-benzylammonium chloride (1:1) = CAS registration number 21056-86-0, N-hexadecyl-N,N-bis(2-hydroxyethyl)-benzylammonium chloride (1:1) = CAS registration number 65151-47-5, N,N-bis(2-hydroxyethyl)-N-methyl-1-dodecylammonium chloride (1:1) = 22340-01-8, 2,2-diethyl-2,3-dihydro-1H-isoindolium = CAS registration number 768297-35-4, 2,2-dimethyl-2,3-dihydro-1H-isoindolium chloride and 2,2-dimethyl-2,3-dihydro-1H-isoindolium bromide.

[0052] Other examples of compounds with quaternary N-atoms are pyridinium salts, such as 1,1'-bis(β-hydroxyethyl)-4,4'-bipyridinium diiodide = CAS Reg. No. 25015-61-6, [p-(2,3-dihydroxypropoxy)phenyl]trimethylammonium bromide = CAS Reg. No. 109732-00-5, [m-(2,3-dihydroxypropoxy)phenyl]trimethylammonium bromide = CAS Reg. No. 109731-98-8, [2-[p-(2,3-dihydroxypropoxy)phenoxy]ethyl ...2-00-5 Ammonium iodide = CAS Reg. No. 110056-43-4, and quaternary aminodiols having a quaternary amino group in the side chain, for example 2,3-dihydroxy-N,N,N-trimethyl-1-propylammonium = CAS Reg. No. 44814-66-6, N-(2,3-dihydroxypropyl)-N,N-dimethyl-benzylammonium chloride (1:1) = CAS Reg. No. 417702-31-9 or N-(2,3-dihydroxypropyl)-N,N-dimethyl-benzylammonium hydroxide (1:1) = CAS Reg. No. 1043415-27-5.

[0053] In a further preferred embodiment, the aminodiol has a tertiary amino group containing a benzyl group, for example N,N-bis(2-hydroxyethyl)-N-methyl-benzylammonium bromide (1:1), i.e. CAS registration number 1254832-90-0, N-dodecyl-N,N-bis(2-hydroxyethyl)-benzylammonium chloride (1:1) = CAS registration number 19379-90-9 or N-(2,3-dihydroxypropyl)-N,N-dimethyl-benzylammonium chloride (1:1) = CAS registration number 417702-31-9.

[0054] A.3. Polymer polyols

[0055] Preferred polymer polyols include polycarbonate polyols, polyether polyols, polyacrylate polyols, polyester polyols, polyamide polyols and polyolefin polyols. More preferred polymer polyols are polyester polyols, and most preferred are polyester diols obtained by reacting polycarboxylic acids and polyols.

[0056] Polyester polyol is a resin formed by an esterification reaction or transesterification reaction between at least one aromatic polycarboxylic acid component and at least one polyol component. Specific examples of aromatic polycarboxylic acids include dibasic acids, such as phthalic acid, isophthalic acid, terephthalic acid, 2,6-naphthalene dicarboxylic acid, 1,4-naphthalene dicarboxylic acid, 1,5-naphthalene dicarboxylic acid; trivalent or higher polycarboxylic acids, such as trimellitic acid and pyromellitic acid; and anhydrides thereof; for example, phthalic anhydride, trimellitic anhydride, pyromellitic anhydride; and the like. As aromatic polycarboxylic acid components, one or more dibasic acids selected from the above-mentioned dibasic acids, lower alkyl ester compounds of these acids, and anhydrides are mainly used. If necessary, monobasic acids such as benzoic acid, crotonic acid or p-tert-butylbenzoic acid; trivalent or higher polycarboxylic acids, such as trimellitic anhydride, methylcyclohexene tricarboxylic acid or pyromellitic anhydride; or the like can be further used in combination with the polycarboxylic acid component. It is preferred to use dicarboxylic acids to prepare polyesters which produce linear polymer chains, in particular 1,4-terephthalic acid copolymers produce better properties than phthalic anhydride copolymers with respect to colloidal stability in aqueous media. In addition to terephthalic acid, other para- or linearly substituted polycarboxylic acids may be used to obtain the desired properties, such as 2,6-naphthalene dicarboxylic acid or 1,5-naphthalene dicarboxylic acid.

[0057] Preferred carboxylic acids are aromatic dicarboxylic acids, such as terephthalic acid and isophthalic acid. The content of aromatic acid in the resin is equal to or higher than 30 mol%, and preferably equal to or higher than 50 mol%, relative to the total amount of dicarboxylic acids or anhydrides. Treatment liquids containing polyurethane resins obtained by reaction of polyester polyols containing aromatic polycarboxylic acids do show improved colloidal stability and result in images with improved solvent resistance and improved resistance to dry and wet scratches. The good results obtained with terephthalic acid and isophthalic acid may be related to obtaining a certain amount of polyurethane resin crystallinity or providing linear amorphous chains that are more conducive to desired physical properties (such as scratch resistance and solvent resistance). The introduction of phthalic anhydride or isophthalic acid in terephthalic acid-based polyesters reduces the crystallinity or the distance between chain ends and improves solubility in organic solvents. For polyester polyols based on terephthalic acid, it is preferred to use copolymers of terephthalic acid with isophthalic acid or phthalic anhydride, more preferably with at least 20 mol% of isophthalic acid or phthalic anhydride units. For the same reasons, polyester polyols with only phthalic anhydride are not as preferred as copolymers with terephthalic acid incorporated therein. Polyester polyols based only on phthalic anhydride are readily soluble in the polymerization solvents used for PU preparation, but the dried coating will also have a lower solvent resistance. It is therefore preferred that the aromatic polyester polyol contains between 20 mol% and 80 mol% of terephthalate groups, based on the total amount of dicarboxylic acids (or anhydrides) in the polyester polyol.

[0058] Very suitable polyester polyols containing terephthalate units and isophthalate units in a ratio of 1:1 mol % are: Dynacoll 7150 supplied by Evonik, Marl, Germany; Vylon 220 from Toyobo, Osaka, Japan; and Elitel 1401 from Unitika Ltd Dusseldorf, Germany.

[0059] In order to obtain the desired properties of polyester polyols and to use high levels of terephthalic acid, mixtures of dicarboxylic acids may also be used. For example, to reduce the crystallinity, a mixture of terephthalic acid and adipic acid may be used. Thus, polyester polyols based on mixtures of aromatic polycarboxylic acids and aliphatic dicarboxylic acids (such as adipic acid, succinic acid, methylcyclohexenetricarboxylic acid, fumaric acid and sebacic acid) or anhydrides (such as tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride and succinic anhydride) may also be used.

[0060] Polyester polyols with a high content of terephthalic acid may have poor solubility in the production solvents used for PU production (e.g. acetone) or may have too high a crystallinity to obtain good adhesion properties. In particular, this is the case when only non-branched diols are used for the polyester polyols, such as 1,2-ethylene glycol or 1,4-butanediol. When using terephthalic acid-based polyester polyols with more than 35 mol % terephthalic acid, mixtures of different non-branched diols (e.g. a mixture of 1,2-ethylene glycol and 1,4-butanediol) or mixtures of non-branched diols (e.g. ethylene glycol) with branched diols (e.g. neopentyl glycol) may be preferably used. When a mixture of different diols is used for the polyester polyol, a high terephthalic acid content may be used, even up to 100 mol % based on the total dicarboxylic acid content.

[0061] Specific examples of the polyol component include glycols, such as ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,4-hexanediol and 1,6-hexanediol; and trivalent or higher polyols, such as glycerol, trimethylolethane, trimethylolpropane and pentaerythritol. For the polyol component, the above-mentioned glycols are mainly used, and if necessary, trivalent or higher polyols, such as glycerol, trimethylolethane, trimethylolpropane and pentaerythritol, can be further used in combination with glycols. Aromatic glycols can also be used to increase the content of the aromatic part in the polyester polyol. Suitable aromatic diols are: p-xylene glycol, 1,5-naphthalenedimethanol, 1,4-naphthalenedimethanol, 4,4′-bis(hydroxymethyl)biphenyl, bis(hydroxyethyl)terephthalate, bis(2-hydroxypropyl)terephthalate, 1,5-bis(2-hydroxyethyl)-1,5-naphthalenedicarboxylate, 4,4-bis(hydroxymethyl)diphenylmethane, 2,2-bis(4-β-hydroxyethoxyphenyl)propane (diethoxylated bisphenol A) and bis[p-(2-hydroxyethoxy)phenyl]methane.

[0062] Preferably, a diol having an Mw of equal to or less than 400 is used together with the polyester polyol. These polyols may be used alone or as a mixture of two or more species.

[0063] A.4. Polyether diol

[0064] Polyether diols may be present during the reaction between allophanate-based isocyanates, polyols containing quaternary N-atoms or tertiary amino groups and polymer polyols selected from polyester polyols, polyether polyols, polycarbonate polyols, polyolefin polyols, polyacrylate polyols and polyamide polyols. The polyether diols will be introduced as side chains into the formed PU into the polyether and will further improve the colloidal stabilization of the PU-resin dispersion in the aqueous vehicle.

[0065] The polyether glycol can be obtained by addition polymerization of an alkylene oxide with at least one compound having two or more active hydrogen atoms. Examples of such compounds include ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, trimethylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 1,6-hexanediol, glycerol, trimethylolethane and hydroxyethyl propane. Examples of alkylene oxides include ethylene oxide, propylene oxide, butylene oxide, styrene oxide, epichlorohydrin and tetrahydrofuran. Preferred polyether glycols are compounds according to formula X.

[0066]

[0067] wherein R1 is methyl or ethyl, R2 is H or C1-C4 alkyl, more preferably C1-C4 alkyl and n represents an integer of 5-50, more preferably 10-40 and most preferably 15-30.

[0068] The polyether diols preferably used in the present invention are Ymer N120 or Tegomer D 3403, i.e. α-[2,2-bis(hydroxymethyl)butyl]-ω-methoxy-poly(oxy-1,2-ethanediyl). These diols can be prepared from trimethylolpropane oxetane (TMPO). Fock, J.; V., Polyether-1,2-and-1,3-diols as macromonomers for the synthesis of graft copolymers, 1. Synthesis and characterization of the macromonomers. Die Makromolekulare Chemie 1990, 191(12), 3045-3057 describes a possible synthesis procedure.

[0069] In general, other polyether 1,2- or 1,3-diols may also be used. To obtain good stability, the polyether graft needs to be sufficiently water-soluble to obtain good steric stabilization. In the case of Ymer N120, the polyether consists only of ethylene oxide segments, but this may also be a copolymer of different alkylene oxides. In addition, in the current macromonomer diols, the terminal group is a methoxy group, which may also be other terminal groups, such as hydrophilic terminal groups (such as anionic groups, such as carboxyl groups, sulfate groups, phosphate groups, etc.). The content of polyether diol in the polyurethane resin is preferably 30 wt.% or less, but greater than 1 wt.%, relative to the polyurethane resin, and more preferably the polyether diol content is equal to or less than 15 wt.% and greater than 2 wt.%. A polyether diol content of less than 30 wt.% but greater than 1 wt.% relative to the polyurethane resin has additional improvements in terms of scratch resistance and solvent resistance of the sprayed and dried image relative to a polyether diol content outside this range.

[0070] A.5. Reaction conditions

[0071] As for the conditions for the reaction between the allophanate-based isocyanate, the polyol containing a tertiary amine group or a quaternary N-atom, the optional polyether diol and the polymer polyol, those conventionally used reaction conditions can be used without particular limitation.

[0072] In addition to the preferred terephthalate-containing polyester polyols, mixtures of different polymer polyols can also be used to adjust physical properties, adhesion, mechanical properties, etc. Examples are, for example, polycarbonate polyols, polyether polyols, polyacrylate polyols, aliphatic polyester polyols, polyolefin polyols or other polymer polyols. Examples of polycarbonate polyols are, for example, Oxymer C112, Oxymer M112 (available via Perstorp); Kuraray polyols C-2050, C-2090, C-1090 (available from Kuraray); Converge HMA-1 and Converge HMA-1 (available from Novomer Inc.); Duranol T6002, T6001, T5652, T5651, T5650J, T4672, T4671, T4692 and T4691 (available from Asahi Kasei). Further aliphatic polyester polyols are, for example, conventional (semi-)crystalline or amorphous grades, for example based on hexanediol adipate (e.g. Dynacoll 7372 from Evonik), and polyester polyols based on natural products, such as polyester polyols prepared by using dimer acids or dimer diols (e.g. under the trade name Priplast from Croda), examples being Priplast 3192 and Priplast 1838. The dimer diols, which are the raw materials for the preparation of certain Priplast grades and are available under the trade name Pripol, can also be used as monomers in the synthesis of PUs to modify the physical and adhesion properties.

[0073] In the reaction between the polyester polyol and the organic polyisocyanate compound, a diol having a Mw of 400 or less may be used if necessary. Examples of suitable diols are: ethylene glycol, diethylene glycol, propylene glycol, dipropylene glycol, 1,4-butanediol, neopentyl glycol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,4-hexanediol and 1,6-hexanediol; and trivalent or higher polyols such as glycerol, trimethylolethane, trimethylolpropane and pentaerythritol. 1,4-butanediol is most preferred.

[0074] Examples of organic solvents for the reaction between polyester polyols, polyether diols, polyols containing tertiary amino groups or quaternary N-atoms and organic polyisocyanate compounds include ketones such as acetone and methyl ethyl ketone; ethers such as tetrahydrofuran and dioxane; acetates such as ethyl acetate and butyl acetate; nitriles such as acetonitrile; and amides such as dimethylformamide, N-methylpyrrolidone and N-ethylpyrrolidone. These can be used alone or in combination of two or more.

[0075] Using polyether diols with higher molecular weight than Ymer 120N will produce more phase separation and provide better water dispersibility. However, it is more difficult to dissolve these polyols in organic solvents such as acetone to prepare polyurethane resins. This can be overcome by using a cosolvent during the polycondensation reaction. The preferred cosolvent is 2-pyrrolidone or N-methylpyrrolidone.

[0076] The treatment liquid composition of the present invention contains a polyurethane resin as an essential component. Therefore, it is preferred to disperse the polyurethane resin in water to obtain an aqueous dispersion of the polyurethane resin. Each dispersion technique suitable for preparing an aqueous dispersion can be used.

[0077] B. Treatment Fluid Composition

[0078] The treatment liquid according to the present invention contains a polyurethane resin as described in §A and water. The following are additional components that can be added to the treatment liquid. The amount of polyurethane resin in the treatment liquid is preferably equal to or less than 30 wt.% and equal to or higher than 1 wt.%. The treatment liquid can be applied to the substrate or printed image by coating technology, spraying technology or jet technology.

[0079] B.1. Water-soluble organic solvents

[0080] The treatment liquid of the present invention may contain a water-soluble organic solvent in addition to water as a solvent. Examples of the water-soluble organic solvent include polyols such as diethylene glycol, triethylene glycol, dipropylene glycol, 1,3-propylene glycol, 1,3-butylene glycol, 1,4-butylene glycol, 2,2-dimethyl-1,3-propylene glycol, 2-methyl-1,3-propylene glycol, 1,2-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 1,6-hexanediol, 2-ethyl-1,3-hexanediol, 1,2-hexanediol and 2,5-hexanediol; polyol alkyl ethers such as dipropylene glycol n-propyl ether, tripropylene glycol methyl ether, tripropylene glycol n-propyl ether, propylene glycol phenyl ether, triethylene glycol methyl ether, triethylene glycol methyl ether, triethylene glycol ethyl ether, diethylene glycol n-hexyl ether and ethylene glycol phenyl ether; and nitrogen-containing heterocyclic compounds such as 2-pyrrolidone and N-methylpyrrolidone.

[0081] Other preferred water-soluble organic solvents include ethylene glycol, propylene glycol, 1,2-butanediol, 2,3-butanediol, 2-methyl-2,4-pentanediol, dipropylene glycol monomethyl ether, propylene glycol n-butyl ether, propylene glycol tert-butyl ether, diethylene glycol methyl ether, ethylene glycol n-propyl ether and ethylene glycol n-butyl ether.

[0082] The content of the water-soluble organic solvent in the aqueous inkjet ink is preferably less than 70 wt.%. If the content exceeds 70% by mass, the aqueous treatment liquid loses its water-based nature and thus loses more green characteristics.

[0083] B.2. Surfactants

[0084] In the treatment liquid of the present invention, a surfactant may be added to ensure wettability to the substrate. The amount of the surfactant added as an active component in the ink is preferably 0.1 wt.% to 5 wt.%.

[0085] If the added amount is less than 0.1% by mass, wettability to the substrate is insufficient and results in reduced image quality and adhesion to the substrate. The surfactant that can be used is not particularly limited as long as it satisfies the above restrictions.

[0086] Although any of an amphoteric surfactant, a nonionic surfactant or a cationic surfactant can be used, from the viewpoint of the relationship between dispersion stability and image quality, a nonionic surfactant such as polyoxyethylene alkylphenyl ether, polyoxyethylene alkyl ester, polyoxyethylene alkylamine, polyoxyethylene alkylamide, polyoxyethylene propylene block polymer, sorbitan fatty acid ester, polyoxyethylene sorbitan fatty acid ester and ethylene oxide adduct of acetylene alcohol is preferably used. In addition, a fluorine-based surfactant and a silicon-based surfactant can be used in combination (or alone) according to the formulation.

[0087] Suitable surfactants are: silicone-based surfactants, such as TegoTwin 4000 from Evonik Industries, Tegowet 270 from Evonik Industries, Hydropalat WE3220 from BASF; silane-based surfactants, such as Silwet HS312 from Momentive; and fluorosurfactants, such as Thetawet FS8150 from Neochem GMBH, Capstone FS3100 from Dupont, TividaFL2500 from Merck and Dynol, Envirogem & Surfynol series surfactants from Evonik.

[0088] B.3. Additives

[0089] Along with the polyurethane resin, polyvalent metal ions may be included in the treatment solution. Suitable examples are polyvalent metal ions composed of divalent or higher valent metal cations such as magnesium, calcium, strontium, barium, zirconium and aluminum and anions such as fluoride (F - ), chloride ion (Cl - ), bromide ion (Br - ), sulfate ion (SO4 2- ), nitrate ion (NO3 - ) and acetate ions (CH3COO - ) formed by water-soluble metal salts.

[0090] These polyvalent metal ions have the function of aggregating the ink by acting on the anionic groups (such as carboxyl groups) on the surface of the pigment or in the dispersed polymer of the capsule contained in the ink. As a result, the ink remains on the surface of the substrate to improve the color development characteristics. Therefore, it is preferred that the surface of the pigment in the ink and / or the dispersed binder and / or latex contained in the ink have anionic groups selected from carboxyl groups, sulfonate groups and phosphonate groups, most preferably carboxyl groups.

[0091] The treatment liquid may further contain an organic acid. Preferred examples of organic acids include, but are not limited to, acetic acid, propionic acid, and lactic acid.

[0092] The treatment fluid may also contain a colorant, such as a pigment. Particularly useful for printing on dark substrates such as dark leather, fabric or cardboard are treatment fluids containing white pigments. A preferred pigment for aqueous treatment fluid inks is titanium dioxide. Titanium dioxide (TiO2) pigments useful in the present invention may be in rutile or anatase crystalline form. Methods for preparing TiO2 are described in more detail in "The Pigment Handbook", Volume I, 2nd Edition, John Wiley & Sons, NY (1988), the relevant disclosures of which are incorporated herein by reference for all purposes as if fully set forth.

[0093] The titanium dioxide particles can have various average particle sizes of about 1 micron or less, depending on the desired end-use application of the treatment fluid. For applications requiring high hiding or decorative printing applications, the titanium dioxide particles preferably have an average size of less than about 1 μm. Preferably, the particles have an average size of about 50 to about 950 nm, more preferably about 75 to about 750 nm, and still more preferably about 100 to about 500 nm.

[0094] Additionally, a variety of particle sizes can be used to achieve unique advantages, such as opacity and UV protection. These various sizes can be achieved by adding both pigments and nano-sized TiO2.

[0095] The titanium dioxide pigment may also be provided with one or more metal oxide surface coatings. These coatings may be applied using techniques known to those skilled in the art. Examples of metal oxide coatings include silicon dioxide, aluminum oxide, aluminum oxide silicon oxide, boron oxide, and zirconium oxide, among others. These coatings may provide improved properties, including reduced photoreactivity of the titanium dioxide. Metal oxide coatings of aluminum oxide, aluminum oxide silicon oxide, boron oxide, and zirconium oxide produce positively charged surfaces of the TiO2 pigment, and are therefore particularly useful in combination with the cationically stabilized polyurethanes of the present invention, since no additional surface treatment of the pigment is required.

[0096] Commercial examples of such coated titanium dioxide include R700 (alumina coated, available from EI DuPont de Nemours, Wilmington Del.), RDI-S (alumina coated, available from Kemira Industrial Chemicals, Helsinki, Finland), R706 (available from DuPont, Wilmington Del.) and W-6042 (silicon oxide alumina treated nano-sized titanium dioxide from Tayco Corporation, Osaka, Japan). Other suitable white pigments are given in Table 2 in

[0116] of WO 2008 / 074548. White pigments are preferably pigments having a refractive index greater than 1.60. White pigments may be used alone or in combination. Preferably titanium dioxide is used as a pigment having a refractive index greater than 1.60. Suitable titanium dioxide pigments are preferably of the rutile type. Commercially available rutile titanium oxide products include Tipaque (registered trademark) CR-60-2, Tipaque CR-67, Tipaque R-980, Tipaque R-780, Tipaque-850, Tipaque R-980, Tipaque R-630, Tipaque R-670, Tipaque PF-736 (each a product of Ishihara Sangyo Kaisha TRONOX CR 834 from Tronox Pigments BV).

[0097] Ink Set

[0098] The ink set according to the invention comprises a treatment fluid composition as described in § B. and an aqueous inkjet ink comprising a colorant.

[0099] Aqueous inkjet inks preferably contain a solvent and a latex binder.

[0100] C.1. Solvent

[0101] The aqueous medium of the ink contains water, but may preferably include one or more water-soluble organic solvents. One or more organic solvents may be added for various reasons. For example, it may be advantageous to add a small amount of organic solvent to improve the dissolution of the compound in the inkjet ink to be prepared. Preferred water-soluble organic solvents are polyols (e.g., ethylene glycol, glycerol, 2-ethyl-2-(hydroxymethyl)-1,3-propanediol, tetraethylene glycol, triethylene glycol, tripropylene glycol, 1,2,4-butanetriol, diethylene glycol, propylene glycol, dipropylene glycol, butanediol, 1,6-hexanediol, 1,2-hexanediol, 1,5-pentanediol, 1,2-pentanediol, 2,2-dimethyl-1,3-propanediol, 2-methyl-2,4-pentanediol, 3-methyl-1,5-pentanediol, 3-methyl-1,3-butanediol and 2-methyl-2,4-pentanediol). The invention also includes butanol, 1,3-propanediol, amines (e.g., ethanolamine and 2-(dimethylamino)ethanol), monohydric alcohols (e.g., methanol, ethanol and butanol), alkyl ethers of polyhydric alcohols (e.g., diethylene glycol monomethyl ether, diethylene glycol monobutyl ether, triethylene glycol monomethyl ether, triethylene glycol monobutyl ether, ethylene glycol monomethyl ether, ethylene glycol monobutyl ether, propylene glycol monomethyl ether, propylene glycol monobutyl ether and dipropylene glycol monomethyl ether), 2,2'-thiodiethanol, amides (e.g., N,N-dimethylformamide), heterocycles (e.g., 2-pyrrolidone and N-methyl-2-pyrrolidone) and acetonitrile.

[0102] C.2. Colorants

[0103] Colorants that may be included in the inkjet ink may be dyes or pigments.

[0104] The pigment may be black, white, cyan, magenta, yellow, red, orange, violet, blue, green, brown, mixtures thereof, etc. The colored pigment may be selected from those disclosed by HERBST, Willy et al. Industrial Organic Pigments, Production, Properties, Applications. 3rd edition. Wiley-VCH, 2004. ISBN 3527305769.

[0105] Suitable pigments for the inkjet inks of the present invention are disclosed in paragraphs

[0128] to

[0138] of WO 2008 / 074548. The pigment particles are dispersed in an aqueous medium using a polymeric dispersant, a (anionic) surfactant, but preferably a self-dispersing pigment is used. The latter prevents interaction of the polymeric dispersant with the dispersing groups of the resin particles of the present invention which may be included in the inkjet ink (see below), since the dispersion stabilization of the pigment is achieved by the same electrostatic stabilization techniques used for the resin particles.

[0106] Self-dispersible pigments are pigments having covalently bonded anionic hydrophilic groups on their surfaces, such as salt-forming groups or groups identical to the dispersing groups of the resin particles, which allow the pigment to be dispersed in aqueous media without the use of surfactants or resins.

[0107] The technology for preparing self-dispersible pigments is well known. For example, EP1220879A discloses a pigment to which a) at least one steric group and b) at least one organic ionic group and at least one amphiphilic counterion are attached, wherein the amphiphilic counterion has a charge opposite to that of the organic ionic group suitable for inkjet inks. EP906371A also discloses suitable surface-modified colored pigments to which hydrophilic organic groups containing one or more ionic groups or ionizable groups are attached. Suitable commercially available self-dispersible colored pigments are, for example, CAB-O-JET from CABOT. TM Inkjet colorants.

[0108] The pigment particles in the inkjet ink should be small enough to allow the ink to flow freely through the inkjet printing device, especially at the ejection nozzle. It is also desirable to use small particles to obtain maximum color intensity and slow down sedimentation.

[0109] The average pigment particle size is preferably between 0.050 and 1 μm, more preferably between 0.070 and 0.300 μm, and particularly preferably between 0.080 and 0.200 μm. Most preferably, the numerical average pigment particle size is not greater than 0.150 μm.

[0110] However, for white pigment inkjet inks, the numerical average particle size of the white pigment is from about 50 to about 950 nm, more preferably from about 75 to about 750 nm, and still more preferably from about 100 to about 500 nm.

[0111] Suitable white pigments are given in Table 2 of

[0116] of WO 2008 / 074548. White pigments are preferably pigments with a refractive index greater than 1.60. White pigments may be used alone or in combination. Preferably titanium dioxide is used as the pigment with a refractive index greater than 1.60. Suitable titanium dioxide pigments are the same as described in §B.3. Special colorants may also be used, such as fluorescent pigments for special effects on clothing and metallic pigments for printing silver and gold luxury looks on fabrics.

[0112] Suitable polymer dispersants for pigments are copolymers of two monomers, but they may contain 3, 4, 5 or even more monomers. The properties of the polymer dispersant depend on both the nature of the monomers and their distribution in the polymer. The copolymer dispersant preferably has the following polymer composition:

[0113] Statistically polymerize monomers (e.g. monomers A and B polymerize to form ABBAABAB);

[0114] Alternating monomers (e.g. monomers A and B polymerize to form ABABABAB);

[0115] Gradient polymerization of monomers (e.g. monomers A and B polymerize into AAABAABBABBB);

[0116] Block copolymers (e.g. monomers A and B polymerized to AAAAABBBBBB) where the block length of each block (2, 3, 4, 5 or even more) is important to the dispersing ability of the polymeric dispersant;

[0117] Graft copolymers (graft copolymers consist of a polymer backbone with polymer side chains attached to the backbone); and

[0118] Mixed forms of these polymers, such as block gradient copolymers.

[0119] Suitable dispersants are DISPERBYK available from BYKCHEMIE TM Dispersants, JONCRYL available from JOHNSON POLYMERS TM Dispersants and SOLSPERSE available from ZENECA TM Dispersants. A detailed list of non-polymeric as well as some polymeric dispersants is disclosed by MC CUTCHEON. Functional Materials, North American Edition. Glen Rock, NJ: Manufacturing Confectioner Publishing Co., 1990. p. 110-129.

[0120] The number average molecular weight Mn of the polymeric dispersant is preferably between 500 and 30000, more preferably between 1500 and 10000. The polymeric dispersant preferably has a weight average molecular weight Mw of less than 100,000, more preferably less than 50,000, and most preferably less than 30,000.

[0121] The pigment is preferably present in the range of 0.01-20%, more preferably in the range of 0.05-10% by weight and most preferably in the range of 0.1-5% by weight, each based on the total weight of the inkjet ink. For white inkjet inks, the white pigment is preferably present in an amount of 3%-40% and more preferably 5%-35% by weight of the inkjet ink. An amount less than 3% by weight may not achieve sufficient covering power.

[0122] C.3. Latex adhesive

[0123] The inkjet ink composition according to the ink set of the present invention may further comprise a latex binder. Latex binders are generally added to inkjet ink formulations to achieve good adhesion of the pigment to the substrate. Latex is a polymer, and suitable latexes may be acrylic-based latexes, polyurethane-modified polyester latexes, more preferably polyurethane-modified polyester latexes.

[0124] The polyurethane latex is incorporated into the ink formulation as a dispersion and can be selected from, for example, aliphatic polyurethane dispersions, aromatic polyurethane dispersions, anionic polyurethane dispersions, nonionic polyurethane dispersions, aliphatic polyester polyurethane dispersions, aliphatic polycarbonate polyurethane dispersions, aliphatic acrylic modified polyurethane dispersions, aromatic polyester polyurethane dispersions, aromatic polycarbonate polyurethane dispersions, aromatic acrylic modified polyurethane dispersions, or a combination of two or more thereof.

[0125] The preferred polyurethane latex used as the dispersant in the ink of the present invention is a polyester latex comprising a structural unit containing a polyurethane bond. Among such latexes, a water-soluble or water-dispersible polyurethane-modified polyester latex is preferred. It may be preferred that the polyurethane-modified polyester latex comprises at least one structural unit derived from a hydroxyl-containing polyester resin (polyester polyol) and at least one structural unit derived from an organic polyisocyanate.

[0126] The preferred polyurethane latex to be included in the ink of the present invention is a polyurethane latex obtainable by reacting a polyester polyol, a polyether diol, a polyol containing an anionic group and a polyisocyanate. A particularly preferred polyurethane latex is a polyurethane latex obtainable by reacting a polyester polyol, a polyether diol, a polyol containing an anionic group and a polyisocyanate, and wherein the polyester polyol is obtained by reacting an aromatic polycarboxylic acid and a polyol. Suitable polyurethane latexes and examples of their preparation are disclosed in patent application WO2018 / 077624.

[0127] Some examples of suitable polyurethane latexes are, for example, NEOREZ R-989, NEOREZ R-2005, and NEOREZ R-4000 (DSM NeoResins); BAYHYDROL UH 2606, BAYHYDROL UH XP 2719, BAYHYDROL UH XP2648, and BAYHYDROL UA XP 2631 (Bayer Material Science); DAOTAN VTW 1262 / 35WA, DAOTAN VTW 1265 / 36WA, DAOTAN VTW 1267 / 36WA, DAOTAN VTW 6421 / 42WA, DAOTAN VTW6462 / 36WA (Cytec Engineered Materials Inc., Anaheim CA); and SANCURE 2715, SANCURE 20041, SANCURE 2725 (Lubrizol Corporation), or a combination of two or more thereof.

[0128] Acrylic latexes include polymers of acrylic acid monomers, polymers of methacrylic acid monomers, and copolymers of the above monomers with other monomers. These latexes exist as particle suspensions with an average diameter of about 30 nm to about 300 nm. Acrylic latex polymers are formed from acrylic acid monomers or methacrylic acid monomer residues. Examples of acrylic latex polymer monomers include, for example, acrylic acid monomers (such as acrylates, acrylamides, and acrylic acid) and methacrylic acid monomers (such as methacrylates, methacrylamides, and methacrylic acid). Acrylic latex polymers can be homopolymers or copolymers of acrylic acid monomers and other monomers, such as vinyl aromatic monomers, including but not limited to styrene, styrene-butadiene, p-chloromethylstyrene, divinylbenzene, vinylnaphthalene, and divinylnaphthalene.

[0129] Some examples of suitable acrylic latex polymer suspensions are, for example, JONCRYL 537 and JONCRYL 538 (BASF Corporation, Port Arthur TX); CARBOSET GA-2111, CARBOSET CR-728, CARBOSET CR-785, CARBOSET CR-761, CARBOSET CR-763, CARBOSET CR-765, CARBOSET CR-715, and CARBOSET GA-4028 (Lubrizol Corporation); NEOCRYL A-1110, NEOCRYL A-1131, NEOCRYL A-2091, NEOCRYL A-1127, NEOCRYL XK-96, and NEOCRYL XK-14 (DSM); and BAYHYDROL AH XP 2754, BAYHYDROL AH XP 2741, BAYHYDROL A 2427, and BAYHYDROL A2651 (Bayer), or a combination of two or more thereof.

[0130] The concentration of latex in the inkjet ink according to the present invention is at least 1 wt.% and preferably below 30 wt.%, more preferably below 20 wt.%.

[0131] A.2.4. Additives

[0132] The aqueous inkjet ink may further contain surfactants, humectants, biocides, film formers and thickeners as additives.

[0133] A humectant is preferably incorporated into the inkjet ink to prevent nozzle clogging. This prevention is due to its ability to slow down the evaporation rate of the solvent, especially water in the ink. The humectant is preferably an organic solvent having a boiling point higher than that of water. A preferred humectant is glycerol. The humectant is preferably added to the liquid formulation in an amount of 0.1-20 wt. % based on the total weight of the liquid.

[0134] Biocides may be added to the ink to prevent the growth of unwanted microorganisms that may be present in the liquid. Biocides may be used alone or in combination. Suitable biocides for use in the inkjet inks of the present invention include sodium dehydroacetate, 2-phenoxyethanol, sodium benzoate, sodium pyridinethion-1-oxide, ethyl p-hydroxybenzoate, and 1,2-benzisothiazolin-3-one and its salts.

[0135] A preferred biocide is Proxel available from ARCH UK BIOCIDES TM GXL and ProxelTM Ultra5 and Bronidox available from COGNIS TM .

[0136] The biocide is preferably added to the aqueous medium in an amount of 0.001 to 3 wt. %, more preferably 0.01 to 1.0 wt. %, each based on the ink liquid.

[0137] D. Application method of treatment fluid

[0138] The treatment liquid according to the invention is suitable for treating different substrates, both porous and non-porous. Porous substrates include paper, paperboard, white pulp-lined chipboard, corrugated board, packaging board, wood, ceramics, stone, leather, synthetic leather and fabric. Non-porous substrates include metal, synthetic leather, glass, polypropylene, polyvinyl chloride, PET, PMMA, polycarbonate, polyamide, polystyrene or copolymers thereof. The treatment liquid according to the invention is particularly suitable for substrates with low absorption, such as paper or leather having a coating on its surface. The treatment liquid according to the invention is also suitable for treating images that have been ejected, usually referred to as post-treatment liquids.

[0139] In particular, for natural leather, a base coat is applied to the crust leather (which is obtained after tanning, drying and softening) to provide a quality commensurate with the luxurious aspects of the leather. The base coat can be applied as a single layer, or it can be applied as multiple layers. The multiple layers can even have different compositions for improving properties such as adhesion or flexibility.

[0140] The basecoat preferably comprises a polyurethane based polymer or copolymer as this has been found to improve the flexibility of the leather.

[0141] Suitable polyurethanes include Urepal from CHEMIPAL SpA TM PU147 and PU181; Melio from STAHL TM Promul 61; Astacin from BASF TM Finish PS; Ecrothan from MICHELMAN TM 4075, 4078 and 4084; Incorez from INCOREZ TM CS8073 and CS065-195. The dry weight of polyurethane in the base coat is preferably 1-6 g / m 2 within the range.

[0142] Although polyurethane is preferred as the polymer for the basecoat, other polymers may be preferably used in combination with polyurethane. Such polymers preferably have an elongation at break of greater than 200%, more preferably 300%. The elongation at break is measured according to ISO 527-2, for example using an MTS Exceed 1000 from MTS Systems Corporation. TM Test equipment.

[0143] Another preferred polymer type for the basecoat is polyacrylate. Polyacrylates provide good flexibility and stabilize the pigment dispersion in the basecoat.

[0144] In a preferred embodiment, the basecoat preferably comprises a polyurethane-based polymer or copolymer and a polyacrylate-based polymer or polymers. This combination can bring excellent flexibility even in the presence of pigments.

[0145] Preferred polyacrylates are Roda TM Base 5514 and Primal from LANXESS TM HPB980. A suitable polymer acrylate emulsion is Bioflex from LMF Biokimica TM KGA.

[0146] A crosslinking agent may be incorporated into the base coat to improve the strength of the base coat and the adhesion to the crust leather. Preferred crosslinking agents include aldehyde-based crosslinking agents such as formaldehyde, melamine formaldehyde derivatives, urea-formaldehyde resins, glyoxal and glutaraldehyde, epoxides, oxazolines, carbodiimides and isocyanates, with isocyanates being particularly preferred. The dry weight of the crosslinking agent in the base coat is preferably less than 1.4 g / m 2 , more preferably less than 1.0 g / m 2 .

[0147] The primer layer is preferably applied by spray coating, but may be applied by any known coating technique, such as blade coating, extrusion coating, slide hopper coating, and curtain coating.

[0148] The base coat preferably has a color similar to the color of the leather and the grain. Any desired color can be selected for the leather or the grain and the base coat, such as red, green, brown, black, blue ...

[0149] All well-known conventional methods can be used to apply or impregnate the treatment liquid according to the present invention onto the substrate or onto the image formed by spraying the aqueous inkjet ink. Examples of methods include air knife coating, blade coating, roller coating, gravure coating and spraying techniques such as inkjet, valve jet and spraying. After the treatment liquid is applied to the substrate, the coating is preferably dried before the image is printed onto the treated substrate.

[0150] The treatment fluid is particularly suitable for treating non-porous or low-absorbing substrates before or after printing an image using inkjet printing.

[0151] The treatment liquid is also suitable for treating textiles. The textile used is made of one type of fiber or two or more blended fibers selected from cotton, hemp, rayon, acetate, silk, nylon and polyester. The fabric can be in any form, such as a woven, knitted or non-woven form of the above fibers. The treatment liquid containing polyurethane resin according to the present invention can be preferably applied to the fabric by spraying, coating, padding or pad printing. Alternatively, an inkjet head or a valve jet head can also be used to apply the pre-treatment liquid to the fabric. The means of applying the treatment liquid has the following advantages: the amount of treatment liquid required is significantly lower than other application methods. Through the jet head, the treatment liquid can be applied to the fabric area where the image should be printed. Suitable inkjet head types for applying the treatment liquid are piezoelectric, continuous, thermal printing head or valve jet type.

[0152] Prior to the subsequent spraying step with the pigmented ink, the fabric to which the treatment liquid has been applied may be dried and optionally subjected to a heat treatment. Examples of heating methods include, but are not limited to, hot pressing, atmospheric steaming, high pressure steaming, and THERMOFIX. Any heat source may be used for the heating method; for example, infrared lamps are used.

[0153] In another preferred embodiment of the present invention, the treatment liquid is not substantially dried after having been applied to the substrate and before the image is printed by jetting the aqueous inkjet ink.

[0154] E. Examples

[0155] E.1. Measurement methods

[0156] E.1.1. Color measurement using X-Rite TM The reflectance spectrum of each sample was measured twice (and then averaged) with an eXact spectrophotometer in the range of 400 to 700 nm with a step size of 10 nm. The CIEL*a*b* coordinates were determined for a 2° observer and a D50 illuminant.

[0157] The Commission Internationale de l'Eclairage (CIE) defines chromaticity as the colorfulness of an area, determined as the ratio of the brightness of a similarly illuminated area that appears white or highly transparent (http: / / eilv.cie.co.at / ). The higher the chromaticity, the more vivid it is compared to a gray (or white) of the same brightness. According to CIE 15 Technical report: Colorimetry, 3rd edition: 2004, chromaticity can be calculated as follows:

[0158] CIE1976α,b(CIELAB) chromaticity:

[0159] Saturation generally indicates the degree to which chromaticity contributes to the overall color impression. Perceived saturation Sa is defined by Eva Lübbe (ISBN 978-3-7881-4057-1) according to the following formula b Depends on the chromaticity Ca of the object b * and lightness L*, and can quantify the color of an object:

[0160] The color difference between two colors 1 and 2 is determined according to the CIE76 color difference formula and is defined as: A ΔE value ≈ 2.3 corresponds to the JND (Just Noticeable Difference) as described in Sharma, Gaurav (2003). Digital Color Imaging Handbook (1.7.2 ed.). CRC Press. ISBN 0-8493-0900-X.

[0161] E.1.2. Average particle size

[0162] The average particle size of PU dispersion was measured by Zetasizer TM Measured by Nano-S (Malvern Instruments, Goffin Meyvis).

[0163] D.2. Materials Unless otherwise specified, all materials used in the following examples are readily available from standard sources such as Sigma-Aldrich (Belgium) and Acros (Belgium).The water used was demineralized water.

[0164] Acetone is supplied annually by VWR International

[0165] Ymer N120 is a 1,3 glycol polyether supplied by Perstorp

[0166] Dynacol 7150 is a polyether diol and is supplied by Evonik

[0167] Reaxis C708, a catalyst supplied by Reaxis BV, The Netherlands

[0168] IPDI is an isocyanate supplied by Covestro as Desmodur I

[0169] Desmodur XP2565 is an allophanate-based isocyanate according to the general formula I and is the oligomerization product of 3-isocyanatomethyl-3,5,5-trimethylcyclohexyl isocyanate and butan-1-ol and pentan-1-ol and 2-ethylhexan-1-ol, supplied by Covestro

[0170] Tolonate X FLO100 is an allophanate-based isocyanate according to formula I and is supplied by Vencorex Chemicals

[0171] BD is 1,4-butanediol supplied by Acros

[0172] Disperbyk-190 is a 40 wt.% dispersant solution supplied by BYK CHEMIE GMBH

[0173] COL is a commercial cyan dispersion supplied by Cabot Corporation, available under the trade name Cab-O-Jet 450C

[0174] Tronox CR-843 is a titanium dioxide pigment from Tronox Pigments BV

[0175] ·PYR is 2-pyrrolidone

[0176] HD is 1,2-hexanediol

[0177] Proxel K is a 5-10% aqueous solution of 1,2-benzisothiazolin-3-one

[0178] SURF-1 is Capstone FS3100, a surfactant from Dupont

[0179] SURF-2 is Tego Wet 270, a surfactant from Evonik Industries

[0180] OPV is a 5 wt.% aqueous solution of 1,2-benzisothiazolin-3-one potassium salt (CASRN 127553-58-6, commercially available from Prom Chem)

[0181] DISP is a concentrated white pigment dispersion and is prepared as follows: using DISPERLUX TM Distributor 275.00g white pigment Tronox CR-834, 68.75g dispersant DISPERBYK-190 and 2.20g biocide OPV are mixed into 204.05g water. Stirring is continued for 30 minutes. The container is connected to a Dyno Mill-RL grinder filled with 200g of 0.4mm yttrium stabilized zirconia beads ("high wear resistant zirconia grinding media" from TOSOH Co.). The mixture is circulated on the grinder at a speed of 4500t / min for 75 minutes (residence time 10 minutes). During the complete grinding procedure, the contents in the grinder are cooled to keep the temperature below 60°C. After grinding, the dispersion is discharged into a container.

[0182] N,N-bis(2-hydroxyethyl)-N-methyl-benzylammonium bromide (1:1) was synthesized by the reaction of benzyl bromide with N-methyldiethanolamine as follows: 5.96 g of N-methyldiethanolamine was dissolved in 50 mL of anhydrous acetonitrile placed in an ice-cooled bath in a 250 mL three-necked round-bottom flask under a continuous nitrogen flow. A solution of 8.99 g of benzyl bromide in 50 mL of acetonitrile was added dropwise to the reaction solution via an addition funnel. The reaction solution was stirred at ambient temperature for 16 hours. Upon completion, the reaction mixture was washed with a mixture of n-hexane and dichloromethane in a 1:1 ratio and filtered. The residue was dried under reduced pressure in an oven at 40°C for more than 48 hours to obtain the desired product (13.92 g, white solid) in 96% yield.

[0183] Benzazonium chloride: dodecyl(benzyl)diethanolammonium chloride supplied by Sachem under the trade name BEXOC.

[0184] PU-9 dispersion is a replica of the PU-9 dispersion disclosed in published patent application WO2018 / 077624, with a solid content of 41.9 wt.%

[0185] E.3. Preparation of polyurethane resin dispersion

[0186] PU-1(COMP)

[0187] 95.11 g of Dynacoll 7150 (supplied by Evonik) and 94.92 g of acetone were weighed in a 500 mL Erlenmeyer. The solution of Dynacoll 7150 in acetone was stirred vigorously for 60 minutes at room temperature using a magnetic stirrer to obtain a colorless and clear solution. The polyether diol Ymer N120 was preheated in an oven at 80 ° C to obtain a liquid product. 13.96 g of Ymer N120 was added to the solution and stirred for 15 minutes using a magnetic stirrer to obtain a polyol mixture, which was further used for the reaction. In a 500 mL three-necked round-bottom flask equipped with a spiral condenser and a vertical stirrer, 14.89 g of N, N-bis (2-hydroxyethyl) -N-methyl-benzylammonium bromide was dissolved in 70.74 g of acetonitrile placed in a 65 ° C oil bath, and continued for 30 minutes under a continuous nitrogen stream. When the cationic diol is dissolved in acetonitrile, the mixture of Dynacoll and Ymer is added dropwise to the reaction solution via an addition funnel. The reaction solution is slightly turbid at first and becomes clear while adding the polyol mixture at 65°C for 30 minutes. After adding the polyol, rinse the funnel with 19.78g of acetone. A solution of 1.07g Reaxis in 11.87g acetone is further added to the reaction mixture. Subsequently, 34.21g of IPDI is added dropwise via an addition funnel with a pressure balance arm for 20 minutes. The amount of isocyanate is in excess relative to the amount of hydroxyl groups, i.e., NCO / OH=1.53. After adding IDPI, rinse the addition funnel with 3.93g (5ml) of acetonitrile and stir the reaction mixture at 65°C for 2 hours. Subsequently, a solution of 4.80g of BD in 5ml of acetonitrile is added. The reaction mixture is reacted at 55°C for more than 20 hours and then heated at 65°C for 1 hour to achieve complete conversion.

[0188] 338.5g (43.11% solid) of the reaction mixture was weighed in stainless steel. A water-based dispersion was subsequently prepared by adding water during high shear mixing using a Disperlux device. 270.98g of water was added to the PU solution for 20 minutes using a 9cm diameter dissolving stirrer at 900RPM. The emulsion was further stirred for 30 minutes at 900RPM to obtain a 545.9g viscous dispersion. Subsequently, after acetonitrile and acetone were removed from the emulsion at 40°C by rotary vacuum evaporation under reduced pressure, 386.2g of viscous dispersion was obtained. Evaporation began at a pressure of 400mbar, and the pressure gradually decreased until 60mbar. 30.7g of demineralized water was added to the viscous dispersion to obtain a dispersion of 35wt.%. The solid content of the obtained dispersion was measured, i.e. 39.84wt%. The pH of the obtained dispersion was 5.32. The average particle size was 166.7nm.

[0189] PU-2(COMP)

[0190] 103.88g of Dynacoll 7150 and 94.92g of acetone were weighed in a 500mL Erlenmeyer. The solution of Dynacoll 7150 in acetone was vigorously stirred for 60 minutes at room temperature using a magnetic stirrer to obtain a colorless and clear solution. The polyether diol Ymer N120 was preheated in an oven at 80°C to obtain a liquid product. 15.25g of YmerN120 was added to the solution and stirred for 15 minutes using a magnetic stirrer to obtain a polyol mixture, which was further used for the reaction. In a 500mL three-necked round-bottom flask equipped with a spiral condenser and a vertical stirrer, 11.20g of benzozolium chloride was dissolved in 86.46g of acetonitrile placed in a 65°C oil bath for 30 minutes under a continuous nitrogen stream. When the cationic diol was dissolved in acetonitrile, a mixture of Dynacoll and Ymer was added dropwise to the reaction solution via an addition funnel. The reaction solution was slightly turbid at first and became clear while adding the polyol mixture at 65°C for 30 minutes. After adding the polyol, the funnel was rinsed with 15.82g of acetone. A solution of 1.07g of Reaxis C708 in 7.91g of acetone was further added to the reaction mixture. Subsequently, 125.2mmol of IPDI was added dropwise via an addition funnel with a pressure balance arm for 20 minutes. The amount of isocyanate was in excess relative to the amount of hydroxyl groups, i.e., NCO / OH=1.53. After adding IDPI, the addition funnel was rinsed with 7.91g of acetone and the reaction mixture was stirred at 65°C for 2 hours. Subsequently, a solution of 3.91g of BD in 3.92g of acetone was added. The reaction mixture was reacted at 55°C for more than 20 hours and then heated at 65°C for 1 hour to achieve complete conversion.

[0191] 352.50g (42.97% solid) of the reaction mixture was weighed in stainless steel. A water-based dispersion was subsequently prepared by adding water during high shear mixing using a Disperlux device. 281.31g of water was added to the PU solution for 20 minutes using a 9cm diameter dissolving stirrer at 900RPM. The emulsion was further stirred for 30 minutes at 900RPM to obtain a 548.00g viscous dispersion. Subsequently, 409.20g of viscous dispersion was obtained after acetonitrile and acetone were removed from the emulsion at 40°C by rotary vacuum evaporation under reduced pressure. Evaporation began at a pressure of 400mbar, and the pressure gradually decreased until 60mbar. 23.60g of demineralized water was added to the viscous dispersion to obtain a dispersion of 35wt.%. The solid content of the obtained dispersion was measured, i.e. 36.20wt%. The pH of the obtained dispersion was 5.58. The average particle size was 34.8nm.

[0192] PU-3(COMP)

[0193] 102.03g of Dynacoll 7150 and 94.92g of acetone were weighed in a 500mL Erlenmeyer. The solution of Dynacoll 7150 in acetone was stirred vigorously for 60 minutes at room temperature using a magnetic stirrer to obtain a colorless and clear solution. The polyether diol Ymer N120 was preheated in an oven at 80°C to obtain a liquid product. 14.98g of YmerN120 was added to the solution and stirred for 15 minutes using a magnetic stirrer to obtain a polyol mixture, which was further used for the reaction. In a 500mL three-necked round-bottom flask equipped with a spiral condenser and a vertical stirrer, 15.97g of N, N-bis(2-hydroxyethyl)-N-methyl-benzylammonium bromide was dissolved in 70.74g of acetonitrile placed in a 65°C oil bath for 30 minutes under a continuous nitrogen stream. When the cationic diol is dissolved in acetonitrile, the mixture of Dynacoll and Ymer is added dropwise to the reaction solution via an addition funnel. The reaction solution is slightly turbid at first and becomes clear while adding the polyol mixture at 65°C for 30 minutes. After adding the polyol, the funnel is rinsed with 19.78g of acetone. A solution of 1.07g of Reaxis C708 in 11.87g of acetone is further added to the reaction mixture. Subsequently, 25.19g of IPDI is added dropwise via an addition funnel with a pressure balance arm for 20 minutes. The amount of isocyanate is in excess relative to the amount of hydroxyl groups, i.e., NCO / OH=1.05. After adding IDPI, the addition funnel is rinsed with 5ml of acetonitrile and the reaction mixture is stirred at 65°C for 2 hours. Subsequently, a solution of 0.49g of BD in 5ml of acetonitrile is added. The reaction mixture is reacted at 55°C for more than 20 hours and then heated at 65°C for 1 hour to achieve complete conversion.

[0194] 341.5g (42.45% solid) of the reaction mixture was weighed in stainless steel. A water-based dispersion was subsequently prepared by adding water during high shear mixing using a Disperlux device. 269.24g of water was added to the PU solution for 20 minutes using a 9cm diameter dissolving stirrer at 900RPM. The emulsion was further stirred for 30 minutes at 900RPM to obtain a 557.2g viscous dispersion. Subsequently, after acetonitrile and acetone were removed from the emulsion at 40°C by rotary vacuum evaporation under reduced pressure, 380.3g of viscous dispersion was obtained. Evaporation began at a pressure of 400mbar, and the pressure gradually decreased until 60mbar. 33.9g of demineralized water was added to the viscous dispersion to obtain a dispersion of 35wt.%. The solid content of the obtained dispersion was measured, i.e. 38.63wt%. The pH of the obtained dispersion was 5.50. The average particle size was 62.16nm.

[0195] PU-4(INV)

[0196] 61.04 g of Dynacoll 7150 and 87.01 g of acetone were weighed in a 500 mL Erlenmeyer. The solution of Dynacoll 7150 in acetone was vigorously stirred for 60 minutes at room temperature using a magnetic stirrer to obtain a colorless and clear solution. The polyether diol Ymer N120 was preheated in an oven at 80 ° C to obtain a liquid product. 8.96 g of Ymer N120 was added to the solution and stirred for 15 minutes using a magnetic stirrer to obtain a polyol mixture, which was further used for the reaction. In a 500 mL three-necked round-bottom flask equipped with a spiral condenser and a vertical stirrer, 9.56 g of N, N-bis (2-hydroxyethyl) -N-methyl-benzylammonium bromide was dissolved in 70.74 g of acetonitrile placed in a 65 ° C oil bath, and continued for 30 minutes under a continuous nitrogen flow. When the cationic diol is dissolved in acetonitrile, the mixture of Dynacoll and Ymer is added dropwise to the reaction solution via an addition funnel. The reaction solution is slightly turbid at first and becomes clear while adding the polyol mixture at 65°C for 30 minutes. After adding the polyol, the funnel is rinsed with 19.78g of acetone. A solution of 1.01g of Reaxis C708 in 9.4g of acetone is further added to the reaction mixture. Subsequently, 69.14g of Desmodur XP 2565 is added dropwise via an addition funnel with a pressure balance arm for 20 minutes. The amount of isocyanate is in excess relative to the amount of hydroxyl groups, i.e., NCO / OH=1.53. After adding Desmodur XP 2565, the addition funnel is rinsed with 7.86g of acetonitrile and the reaction mixture is stirred at 65°C for 2 hours. Subsequently, a solution of 3.08g of BD in 5ml of acetonitrile is added. The reaction mixture is reacted at 55°C for more than 4 hours to achieve complete conversion.

[0197] 325.11g (41.37% solid) of the reaction mixture was weighed in stainless steel. A water-based dispersion was subsequently prepared by adding water during high shear mixing using a Disperlux device. 249.79g of water was added to the PU solution for 20 minutes using a 9cm diameter dissolving stirrer at 900RPM. The emulsion was further stirred for 30 minutes at 900RPM to obtain a 506g viscous dispersion. Subsequently, after acetonitrile and acetone were removed from the emulsion at 40°C by rotary vacuum evaporation under reduced pressure, 384.29g of viscous dispersion was obtained. Evaporation began at a pressure of 400mbar, and the pressure gradually decreased until 60mbar. 51.8g of demineralized water was added to the viscous dispersion to obtain a dispersion of 35wt.%. The solid content of the obtained dispersion was measured, i.e. 33.69wt.%. The pH of the obtained dispersion was 6.32. The average particle size was 27.7nm.

[0198] PU-5(INV)

[0199] 74.12 g of Dynacoll 7150 and 94.92 g of acetone were weighed in a 500 mL Erlenmeyer. The solution of Dynacoll 7150 in acetone was vigorously stirred for 60 minutes at room temperature using a magnetic stirrer to obtain a colorless and clear solution. The polyether diol Ymer N120 was preheated in an oven at 80 ° C to obtain a liquid product. 10.88 g of Ymer N120 was added to the solution and stirred for 15 minutes using a magnetic stirrer to obtain a polyol mixture, which was further used for the reaction. In a 500 mL three-necked round-bottom flask equipped with a spiral condenser and a vertical stirrer, 7.99 g of benzozolium chloride was dissolved in 70.74 g of acetonitrile placed in a 65 ° C oil bath for 30 minutes under a continuous nitrogen flow. When the cationic diol was dissolved in acetonitrile, the mixture of Dynacoll and Ymer was added dropwise to the reaction solution via an addition funnel. The reaction solution was slightly turbid at first and became clear while adding the polyol mixture at 65°C for 30 minutes. After the addition of the polyol, the funnel was rinsed with 19.78g of acetone. A solution of 1.06g of Reaxis C708 in 11.87g of acetone was further added to the reaction mixture. Subsequently, 62.55g of Desmodur XP 2565 was added dropwise via an addition funnel with a pressure balance arm for 20 minutes. The amount of isocyanate was in excess relative to the amount of hydroxyl groups, i.e., NCO / OH=1.53. After the addition of Desmodur XP 2565, the addition funnel was rinsed with 7.86g of acetonitrile and the reaction mixture was stirred at 65°C for 2 hours. Subsequently, a solution of 2.79g of 1,4-butanediol in 5ml of acetonitrile was added. The reaction mixture was reacted at 55°C for more than 4 hours to achieve complete conversion.

[0200] 344.0g (42.40% solid) of the reaction mixture was weighed in stainless steel. A water-based dispersion was subsequently prepared by adding water during high shear mixing using a Disperlux device. 270.88g of water was added to the PU solution for 20 minutes using a 9cm diameter dissolving stirrer at 900RPM. The emulsion was further stirred for 30 minutes at 900RPM to obtain a 544.00g viscous dispersion. Subsequently, 388g of viscous dispersion was obtained after acetonitrile and acetone were removed from the emulsion at 40°C by rotary vacuum evaporation under reduced pressure. Evaporation began at a pressure of 400mbar, and the pressure gradually decreased until 60mbar. 28.7g of demineralized water was added to the viscous dispersion to obtain a dispersion of 35wt.%. The solid content of the obtained dispersion was measured, i.e. 32.18wt.%. The pH of the obtained dispersion was 5.62. The average particle size was 19.35nm.

[0201] PU-6(INV)

[0202] 79.80 g of Dynacoll 7150 and 98.08 g of acetone were weighed in a 500 mL Erlenmeyer. The solution of Dynacoll 7150 in acetone was vigorously stirred for 60 minutes at room temperature using a magnetic stirrer to obtain a colorless and clear solution. The polyether diol Ymer N120 was preheated in an oven at 80 ° C to obtain a liquid product. 11.71 g of Ymer N120 was added to the solution and stirred for 15 minutes using a magnetic stirrer to obtain a polyol mixture, which was further used for the reaction. In a 500 mL three-necked round-bottom flask equipped with a spiral condenser and a vertical stirrer, 12.49 g of N, N-bis (2-hydroxyethyl) -N-methyl-benzylammonium bromide was dissolved in 78.60 g of acetonitrile placed in a 65 ° C oil bath, and continued for 30 minutes under a continuous nitrogen flow. When the cationic diol was dissolved in acetonitrile, the mixture of Dynacoll and Ymer was added dropwise to the reaction solution via an addition funnel. The reaction solution was slightly turbid at first and became clear while adding the polyol mixture at 65°C for 30 minutes. After the addition of the polyol, the funnel was rinsed with 19.78g of acetone. A solution of 1.09g of Reaxis C708 in 11.87g of acetone was further added to the reaction mixture. Subsequently, 57.25g of Tolonate X FLO100 was added dropwise via an addition funnel with a pressure balance arm for 20 minutes. The amount of isocyanate was in excess relative to the amount of hydroxyl groups, i.e., NCO / OH=1.05. After the addition of Tolonate X FLO100, the addition funnel was rinsed with 3.93g of acetonitrile and the reaction mixture was stirred at 65°C for 2 hours. Subsequently, a solution of 0.38g of BD in 5ml of acetonitrile was added. The reaction mixture was reacted at 55°C for more than 20 hours to achieve complete conversion.

[0203] 353.7g (42.91% solid) of the reaction mixture was weighed in stainless steel. A water-based dispersion was subsequently prepared by adding water during high shear mixing using a Disperlux device. 281.86g of water was added to the PU solution for 20 minutes using a 9cm diameter dissolving stirrer at 900RPM. The emulsion was further stirred for 30 minutes at 900RPM to obtain a 506g viscous dispersion. Subsequently, 387.90g of viscous dispersion was obtained after acetonitrile and acetone were removed from the emulsion at 40°C by rotary vacuum evaporation under reduced pressure. Evaporation began at a pressure of 400mbar, and the pressure gradually decreased until 60mbar. 45.7g of demineralized water was added to the viscous dispersion to obtain a dispersion of 35wt.%. The solid content of the obtained dispersion was measured, i.e. 38.62wt.%. The pH of the obtained dispersion was 5.73. The average particle size was 46.90nm.

[0204] Example 1

[0205] This example illustrates the increase in chroma and color saturation of images obtained by applying an aqueous inkjet ink to a leather substrate when treated with an aqueous pretreatment liquid comprising a polyurethane dispersion based on Desmodur XP as allophanate-based isocyanate and having quaternary ammonium groups with methyl groups on the N-atom.

[0206] Preparation of treatment solution

[0207] Treatment liquids PTL-1 and PTL-2 were prepared by mixing the compounds given in Table 1. All weight percentages are relative to the total weight of the treatment liquids.

[0208] Table 1

[0209] PTL-1(COMP) PTL-2(INV) Compound Content in wt.% Content in wt.% PU-1(COMP) 30.1 PU-4(INV) 35.7 DISP 22.0 22.0 SURF-1 0.8 0.8 HD 15.0 15.0 PYR 15.0 15.0 water Complete to 100% Complete to 100%

[0210] Preparation of INK-1

[0211] Water-based cyan ink INK-1 is mixed Table 2 All weight percentages are relative to the total weight of the ink.

[0212] Table 2

[0213]

[0214]

[0215] Evaluation and Results

[0216] Treatment liquids PTL-1 and PTL-2 were applied to black dyed cow leather sheets coated with a polyurethane-based black pigment layer supplied by Conceria Nuti Ivo SPA (Italy) by using a 20 μm spiral rod (from Elcometer) and an electric film applicator Elcometer 4340. After drying the treatment liquid coating layer in an oven at 60°C for 5 minutes, INK-1 was applied to the treated substrate sheet by a 10 μm spiral rod. The coated sample was dried at 60°C for 6 minutes.

[0217] The reflectance spectrum of each sample was measured according to §E.1.1. The results are shown in Table 3 shown.

[0218] Table 3

[0219] L* a* b* <![CDATA[C ab *]]> <![CDATA[S ab ]]> PTL-1(COMP) 27.35 -6.00 -30.33 30.92 74.91 PTL-2(INV) 32.41 -14.26 -40.15 42.61 79.59

[0220] from Table 3It can be seen that the samples prepared with a set of liquids according to the present invention (PTL-2 + INK-1) are more vivid (higher chromaticity) and more saturated than the samples prepared with a set of liquids not according to the present invention (PTL-1 + INK-1). In addition, the ΔE calculated according to CIE76 ab is 13.79, showing that the colors are visually different.

[0221] Example 2

[0222] This example illustrates the increase in chroma and color saturation of images obtained by applying an aqueous inkjet ink to a leather substrate when treated with an aqueous pretreatment liquid comprising a polyurethane dispersion based on Desmodur XP as allophanate-based isocyanate and having long-chain alkyl groups on the N-atom.

[0223] Preparation of treatment solution

[0224] Treatment liquids PTL-3 and PTL-4 were prepared by mixing the compounds given in Table 4. All weight percentages are relative to the total weight of the treatment liquids.

[0225] Table 4

[0226] PTL-3(COMP) PTL-4(INV) Compound Content in wt.% Content in wt.% PU-2(COMP) 33.2 PU-5(INV) 37.3 DISP 22.0 22.0 SURF-1 0.8 0.8 HD 15.0 15.0 PYR 15.0 15.0 water Complete to 100% Complete to 100%

[0227] Evaluation and Results

[0228] The treatment liquids PTL-3 and PTL-4 and the ink INK-1 were applied in a similar manner to PTL-1, PTL-2, and INK-1 in Example 1.

[0229] The reflectance spectrum of each sample was measured in a similar manner to Example 1. The results are shown in Table 5.

[0230] Table 5

[0231] L* a* b* <![CDATA[C ab *]]> <![CDATA[S ab ]]> PTL-3(COMP) 28.04 -7.39 -31.37 32.23 75.44 PTL-4(INV) 30.30 -13.98 -38.82 41.26 80.60

[0232] from Table 5 It can be seen that the samples prepared with a set of liquids according to the present invention (PTL-4 + INK-1) are more vivid (higher chromaticity) and more saturated than the samples prepared with a set of liquids not according to the present invention (PTL-3 + INK-1). ab The colors shown for 10.20 are visually different.

[0233] Example 3

[0234] This example illustrates the increase in chroma and color saturation of an image obtained by applying an aqueous inkjet ink to a leather substrate when treated with an aqueous pre-treatment fluid comprising a polyurethane dispersion based on Tolonate X FLO100 as allophanate based isocyanate and a quaternary ammonium group having a methyl group as the alkyl group on the N-atom.

[0235] Preparation of treatment fluids PTL-5 and PTL-6

[0236] The treatment liquid PTL-5 and PTL-6 are mixed Table 6 All weight percentages are relative to the total weight of the treatment solution.

[0237] Table 6

[0238] PTL-5(COMP) PTL-6(INV) Compound Content in wt.% Content in wt.% PU-3(COMP) 31.1 PU-6(INV) 31.1 DISP 22.0 22.0 SURF-1 0.8 0.8 HD 15.0 15.0 PYR 15.0 15.0 water Complete to 100% Complete to 100%

[0239] Evaluation and Results

[0240] The treatment liquids PTL-5 and PTL-6 and the ink INK-1 were applied in a similar manner to PTL-1, PTL-2, and INK-1 in Example 1.

[0241] The reflectance spectrum of each sample was measured in a similar manner to Example 1. The results are shown in Table 7.

[0242] Table 7

[0243] L* a* b* <![CDATA[C ab *]]> <![CDATA[S ab ]]> PTL-5(COMP) 28.35 -8.18 -34.35 35.31 77.98 PTL-6(INV) 31.47 -11.42 -37.54 39.24 78.01

[0244] from Table 7 It can be seen that the samples prepared with a set of liquids according to the present invention (PTL-6 + INK-1) are more vivid (higher chromaticity) and more saturated than the samples prepared with a set of liquids not according to the present invention (PTL-5 + INK-1). ab A value of 5.52 shows that the colors are visually different.

Claims

1. An aqueous polyurethane resin dispersion obtainable by reacting an allophanate-based isocyanate according to the general formula I or II, a polyether diol, a polyol containing a quaternary N-atom or a tertiary amino group, and a polyol selected from polyester polyols, polycarbonate polyols, polyacrylate polyols, polyolefins and polyamide polyols; in D, D1 and D2 are independently selected from a linking group having at least 5 carbon atoms R is a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted alkynyl group, a substituted or unsubstituted alicyclic group, a substituted or unsubstituted alkylaryl group, a substituted or unsubstituted aryl group or a heteroaryl group.

2. The aqueous polyurethane resin dispersion according to claim 1, wherein D, D1 or D2 are independently of each other according to the general formula III, IV, V or VI, Therein, the dotted line represents the connection to the N-atom in the general formula I and II and n is an integer from 5 to 11.

3. The aqueous polyurethane resin dispersion according to claim 1, wherein the polyol is a polyester polyol obtained by reacting an aromatic polycarboxylic acid and a polyol, and wherein the polyether diol is according to the general formula X, wherein R1 is methyl or ethyl, R2 is C1-C4 alkyl and n represents an integer of 5-50.

4. The aqueous polyurethane resin dispersion according to claim 3, wherein n represents an integer of 10-40.

5. The aqueous polyurethane resin dispersion according to claim 3, wherein n represents an integer of 15-30.

6. The aqueous polyurethane resin dispersion according to claim 2, wherein the polyol is a polyester polyol obtained by reacting an aromatic polycarboxylic acid and a polyol, and wherein the polyether diol is according to the general formula X, wherein R1 is methyl or ethyl, R2 is C1-C4 alkyl and n represents an integer of 5-50.

7. The aqueous polyurethane resin dispersion according to claim 6, wherein n represents an integer of 10-40.

8. The aqueous polyurethane resin dispersion according to claim 6, wherein n represents an integer of 15-30.

9. The polyurethane resin dispersion according to claim 1, wherein the tertiary amino groups in the resin are protonated.

10. The polyurethane resin dispersion according to claim 6, wherein the tertiary amino groups in the resin are protonated.

11. The polyurethane resin dispersion according to claim 3, wherein the aromatic polycarboxylic acid is selected from the group consisting of phthalic acid, terephthalic acid and isophthalic acid.

12. The polyurethane resin dispersion according to claim 6, wherein the aromatic polycarboxylic acid is selected from the group consisting of phthalic acid, terephthalic acid and isophthalic acid.

13. The polyurethane resin dispersion according to claim 10, wherein the aromatic polycarboxylic acid is selected from the group consisting of phthalic acid, terephthalic acid and isophthalic acid.

14. The polyurethane resin dispersion according to claim 1, wherein the polyether diol is α-[2,2-bis(hydroxymethyl)butyl]-ω-methoxy-poly(oxy-1,2-ethanediyl).

15. The polyurethane resin dispersion according to claim 6, wherein the polyether diol is α-[2,2-bis(hydroxymethyl)butyl]-ω-methoxy-poly(oxy-1,2-ethanediyl).

16. The polyurethane resin dispersion according to claim 10, wherein the polyether diol is α-[2,2-bis(hydroxymethyl)butyl]-ω-methoxy-poly(oxy-1,2-ethanediyl).

17. The polyurethane resin dispersion according to claim 1, wherein the allophanate-based isocyanate contains an alicyclic group.

18. The polyurethane resin dispersion according to claim 1, wherein the polyol containing a quaternary N-atom or an amino group is N,N'-dihydroxyethyl-p-toluidine, 2,2'-(methylimino)diethanol, 3-(dimethylamino)-1,2-propylene glycol, N,N-bis(2-hydroxyethyl)-N-methylbenzylammonium, N-decyl-N,N-bis(2-hydroxyethyl)-benzylammonium, N,N-bis(2-hydroxyethyl)-N-tridecyl-benzylammonium, N-dodecyl-N,N-bis(2-hydroxyethyl)benzylammonium, α,α'-[(dodecylmethylimino)di-2,1-ethanediyl]bis[ω-hydroxypoly(oxy-1,2-ethanediyl) or α,α'-[(dodecylmethylimino)di-2,1-ethanediyl]bis[ω-hydroxypoly(oxy-1,2-ethanediyl).

19. An aqueous treating liquid for inkjet printing, comprising the polyurethane resin as defined in claim 1.

20. An aqueous treating liquid for inkjet printing, comprising the polyurethane resin as defined in claim 10.

21. The aqueous treating liquid for inkjet printing according to claim 19, wherein the aqueous treating liquid further comprises a pigment.

22. An ink set for inkjet printing comprising an aqueous treatment fluid as defined in claim 19 and an aqueous ink comprising a colorant.

23. An inkjet recording method comprising the steps of: (i) providing a substrate; and (ii) applying a treatment liquid as defined in claim 19 onto the surface of the substrate, and optionally drying the applied treatment liquid; and (iii) Printing an image by jetting an aqueous inkjet ink onto the applied treatment liquid.

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