Preparation of a latex using a ternary solvent mixture system

Abstract

The present invention relates to a method of producing latex particles or a latex particle dispersion, a latex particle or a latex particle dispersion produced by the method, the use of the latex particle or latex particle dispersion in a printing ink, a printing ink comprising the latex particle or latex particle dispersion, and a printing method wherein the latex particles are used.

Description

LATER SUBMITTED SHEET 100455W0011Preparation of a latex using a ternary solvent mixture systemTECHNICAL FIELD OF THE INVENTIONThe present invention relates to a method of producing a latex particles dispersion, a latex particles dispersion produced by the method, the use of the latex particles dispersion in a printing ink, a printing ink comprising the latex particles dispersion, and a printing method wherein the latex particles dispersion is used.BACKGROUND OF THE INVENTIONDuring the preparation of latices, particularly for printing inks, usually flammable, carcinogenic, toxic and hard to retrieve solvents like tetrahydrofuran (THF) and methyl ethyl ketone (MEK) that give latices dispersions with broad particle size distribution are used. For example, US 2013233203 A1 and US 2012255460 A1 disclose oil-based printing inks. From an environmental point of view, water-based printing inks and thus latices that are not produced using harmful solvents are preferred, though.Therefore, there is a need for an improved method of producing latex particles dispersion.SUMMARY OF THE INVENTIONThis invention offers a new approach using a green, environmentally friendly, harmless solvent which yields latices with tuneable particle sizes, ranging e.g. from very small particles with 23 nm to larger size with the possibility of a sharp particle size distribution.In a first aspect, the present invention relates to a method of producing a latex particles dispersion, preferably an aqueous particles latex dispersion, comprising dissolving at least one polymeric compound in a solvent mixture comprising a polar organic solvent and a compound of Formula I to produce a solution of the at least one polymeric compound, adding a base to the solution of the at least one polymeric compound, adding water to the solution of the at least one polymeric compound to produce a latex particles dispersion in a ternary solvent mixture, optionally diluting the diluted latex particles dispersion in a ternary solvent mixture to give a diluted latex particles dispersion in a ternary solvent mixture,LATER SUBMITTED SHEET100455W001 preferably, essentially removing the polar organic solvent and the compound of Formula I from the latex particles dispersion in the ternary solvent mixture or the diluted latex particles dispersion in a ternary solvent mixture to produce an aqueous latex particles dispersion;wherein R1and R2are independently selected from H and an alkyl residue with 1 to 6 carbon atoms.A second aspect of the invention relates to a latex particles dispersion produced by the method.Furthermore disclosed is in a third aspect the use of this latex particles dispersion in accordance with the second aspect of the present invention in a printing ink.A fourth aspect of the invention is directed to a printing ink, comprising the latex particles dispersion of the invention.In a fifth aspect, the invention relates to a printing method, comprising: applying a primer liquid on at least one surface of a recording medium; and printing an image with at least one printing ink comprising at least one latex particles dispersion on the surface of the recording medium on which the primer has been applied; wherein the at least one latex particles dispersion comprises the latex particles dispersion of the invention.Further aspects and embodiments of the invention are disclosed in the dependent claims and can be taken from the following description, figures and examples, without being limited thereto.Where appropriate, the above-mentioned configurations and developments can beLATER SUBMITTED SHEET 100455W0013 combined implementations can be combined with each other as desired, as far as this is reasonable. Further possible configurations, developments and implementations of the invention also include combinations, which are not explicitly mentioned, of features of the invention which have been described previously or are described in the following with reference to the embodiments. In particular, in this case, a person skilled in the art will also add individual aspects as improvements or supplements to the basic form of the present invention.BRIEF DESCRIPTION OF THE DRAWINGSThe present invention will become more fully understood from the detailed description given herein below and accompanying schematical drawings which are given by way of illustration only and are not limitative of the invention, and wherein:Fig. 1 shows schematically exemplary method of the present invention.Fig. 2 shows results obtained in the Examples of the present invention.DESCRIPTION OF EMBODIMENTSDetailed embodiments of the present invention are disclosed hereinafter; however, it is to be understood that the disclosed embodiments are merely exemplary of the invention, which can be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually and appropriately detailed structure. In particular, features presented and described in separate dependent claims may be applied in combination and any combination of such claims are herewith disclosed.Further, the terms and phrases used herein are not intended to be limiting; but rather, to provide an understandable description of the invention. The terms “a” or “an”, as used herein, are defined as one or more than one. The term plurality, as used herein, is defined as two or more than two. The term another, as used herein, is defined as at least a second or more. The terms including and / or having, as used herein, are defined as comprising (i.e., open language).LATER SUBMITTED SHEET100455W0014In the present specification, amounts of a substance are usually given as weight percent (wt%, % w / w), unless noted otherwise or clear from the context.As used herein, the terms "comprises", "comprising", “contains”, “containing”, "includes", "including", "has", "having" or any other variation thereof, are intended to cover a nonexclusive inclusion. For example, a process, method, article, or apparatus that comprises a list of elements is not necessarily limited to only those elements, but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Further, unless expressly stated to the contrary, "or" refers to an inclusive or and not to an exclusive or. For example, a condition A or B is satisfied by any one of the following: A is true (or present) and B is false (or not present), A is false (or not present) and B is true (or present), and both A and B are true (or present).The term "essentially" as used herein means that the parameter, event or circumstance described below occurs in its entirety or that the parameter, event or circumstance described below occurs to a large extent or degree. For example, the term "essentially" means that the parameter, event or circumstance described below occurs at least 90% of the time, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99% of the time, or means that the measure or measurement is within at least 90%, or at least 91%, or at least 92%, or at least 93%, or at least 94%, or at least 95%, or at least 96%, or at least 97%, or at least 98%, or at least 99% of the measure or measurement in question.The use of the term "at least one" or "one or more" includes both one and any quantity of more than one.According to a first aspect, the present invention relates to a method of producing a latex particles dispersion, , preferably an aqueous particles latex dispersion, comprising dissolving at least one polymeric compound in a solvent mixture comprising a polar organic solvent and a compound of Formula I to produce a solution of the at least one polymeric compound, adding a base to the solution of the at least one polymeric compound, adding water to the solution of the at least one polymeric compound to produce a latex particles dispersion in a ternary solvent mixture,LATER SUBMITTED SHEET100455W001 optionally diluting the latex particles dispersion in a ternary solvent mixture to give a diluted latex particles dispersion in a ternary solvent mixture, and preferably, essentially removing the polar organic solvent and the compound of Formula I from latex particles dispersion in the ternary solvent mixture or the diluted latex particles dispersion in a ternary solvent mixture to produce an aqueous latex particles dispersion, and optionally separating the latex particles from the latex particles dispersion;wherein R1and R2are independently selected from H and an alkyl residue with 1 to 6 carbon atoms.Particularly, the steps are carried out in this order, as is also clear from the terminology used. However, the steps of adding a base to the solution of the at least one polymeric compound and adding water to the solution of the at least one polymeric compound to produce a ternary solvent mixture can be carried out in this order, together, or vice versa. If the water and the base are added together, it is not excluded that additional water is added, e.g. at higher temperature, and then a further optional dilution step is carried out.In the method, the step of dissolving at least one polymeric compound in a solvent mixture comprising a polar organic solvent and a compound of Formula I to produce a solution of the at least one polymeric compound is not particularly restricted. The dissolving can be done in any way, e.g. by mixing the at least one polymeric compound into the solvent mixture, dissolving the at least one polymeric compound in one of the compound of Formula I and the polar organic solvent, particularly the compound of Formula I, and then adding the other solvent, or adding the solvent mixture to the at least one polymeric compound, etc.In the solvent mixture, the compound of Formula I is particularly used for dissolving theLATER SUBMITTED SHEET100455W0016 at least one polymeric compound. It has surprisingly been found that the compound of Formula I has a high solvency power for polymeric compounds, particularly polyesters.In the compound of Formula I, R1and R2are independently selected from H and an alkyl residue with 1 to 6 carbon atoms, preferably selected from H and an alkyl residue with 1 to 4 carbon atoms, further preferably selected from H and an alkyl residue with 1 and 2 carbon atoms. The alkyl residue can be linear or branched but preferably is linear. The alkyl residue is unsubstituted and saturated. In general, the solvent is more apolar when the alkyl chain is longer, and therefore usually more suited for more apolar resins. R1and R2can be the same or different but preferably are different. Exemplary compounds of Formula I that are suitable include ethylene carbonate, propylene carbonate, 1 ,2-butylene carbonate and cis- and / or trans-2,3-butylene carbonate. Among these, are particularly preferably compound is 1 ,2-butylene carbonate (in the following also abbreviated as BC), i.e. a compound of Formula IIC Formu Ila I III.The compound of Formula I, and particularly the compound of Formula II, is particularly useful due to the high solvency power for the polymers, and particularly polyesters. Further, they show low volatility and a high flash point and are less hazardous than the solvents currently used, e.g. THF and MEK, making them easily usable without the need to impose rigorous, restrictive, and expensive safety precautions and / or expensive and demanding infrastructure. With the compound of Formula I, having a high solvency, high flash point and minimal health risks, the particle size of latices produced can be easily tuned, and due to a high boiling point, a quicker dissolution with reduced viscosity is possible contributing to improved mixing efficiency and consequently influencing particle sizes and distribution. Due to the carbonate function, they can also be used in ternary solvent mixtures with water and a polar organic solvent to provide suitable solutions for producing the latex. Particularly, 1 ,2-butylene carbonate has been found to have a very high solvency power and can be particularly used in a ternary solvent mixture system with a polar organic solvent, particularly an alcohol like 1 -propanol. The solvent is health and food safe, with high boiling point and high flash point, further minimizing theLATER SUBMITTED SHEET100455W0017 operation risks and equipment requirements. Further, the compound of Formula I, particularly of Formula II, is easily detectable, e.g. using a chemical nose, which makes process control easier as well.A further advantage of the compound of Formula I, and particularly the compound of Formula II, is that these compounds can be readily and easily eliminated from the final product by suitable means. For example, a separation can be done by concentration using a semipermeable membrane, dialysis, diafiltration and / or decomposition, particularly of the compound of Formula I, particularly the compound of Formula II, into a prospective alternative to glycerol in an ink recipe.In the step of dissolving the at least one polymeric compound, the polar organic solvent is not particularly restricted. It is preferred that the polar organic solvent essentially does not dissolve the at least one polymeric compound, and the polar organic solvent thus can be chosen accordingly, depending on the at least one polymeric compound.Particularly, the polar organic solvent bridges the polarity gap between the compound of Formula I, particularly the compound of Formula II, and water. Exemplary suitable polar organic solvents include ketones like acetone, alcohols, e.g. aliphatic alcohols like methanol, ethanol, 1 -propanol, 2-propanol, 1 -butanol, 2-butanol, 2-methyl-2-propanol , etc., aromatic alcohols like phenol, benzylic alcohol, cresols, etc., polyols, e.g. diols like ethylene glycol, propylene glycol, etc., triols like glycerol, etc., and mixtures thereof. According to certain embodiments, the polar organic solvent is an alcohol, particularly an aliphatic alcohol. Preferable are polar organic solvents with a higher flash point and / or boiling point from the point of production of the latex particles, while from the point of removal, a polar organic solvent is preferable, and monohydric alcohols with 3 to 8 carbon atoms, e.g. 1-propanol, are preferred. For polyhydric alcohols, the range can be extended. The purpose of the polar organic solvent as co-solvent in the context of this process is mainly to achieve a ternary solvent system with the water added afterwards, and to provide some extra volume to allow efficient mixing and to introduce more distance between the polymeric chains before adding the water, which can guarantee a good distribution of the added water without ending up with big clumps of precipitated polymer). Alcohols prove to be a good choice, as they allow more flexibility and more tunability of the properties of the compound of Formula I, particularly the compound of Formula II. For instance, choosing an alcohol that can decrease the boiling point of the compound of Formula I, particularly the compound of Formula II,LATER SUBMITTED SHEET100455W0018 without compromising the high flash point may allow this, and might also be beneficial for cleaning the synthesis-reactor afterwards. Further, an alcohol with a longer aliphatic tail can act as surfactant for better binding the compound of Formula I, particularly the compound of Formula II, to facilitate washing it out during the removing I purification process. A further option is an alcohol with a low boiling point that can be easily distilled from the removal I purification waste solution and can be reused in the next latex preparation procedure, possibly alongside the compound of Formula I, particularly the compound of Formula II. In this instance, the compound of Formula I, particularly the compound of Formula II, can phase-separate as the alcohol is leaving the mixture and settles at the bottom of the vessel to be collected, as it is denser than water.While the amount of the compound of Formula I and the polar organic solvent are not particularly restricted regarding the amounts and mixing ratio thereof, it is preferred that the compound of Formula I, particularly the compound of Formula II, is contained in an amount that is sufficient to dissolve the at least one polymeric compound. In this regard, it has been surprisingly found that the compound of Formula I, particularly the compound of Formula II, solves the at least one polymeric compound very efficiently, so that the amount thereof can be reduced compared to the usual solvent THF.Particularly, polyesters can be dissolved in the compound of Formula I. In this regard it is also to be noted that a main function of the polar organic solvent is to add volume to the mixture for the later addition of water and to provide for better mixing of the compound of Formula I and the water, similar to an emulsification process, particularly a phase inversion emulsification.According to certain embodiments, the compound of Formula I is contained in the solvent mixture in an amount of 7 to 50 wt.%, based on the solvent mixture, preferably 10 to 45 wt.%, further preferably 20 to 35 wt.%, e.g. 23 to 32 wt.%. According to certain embodiments, the amount of the at least one polymeric compound in relation to solution of the at least one polymeric compound in the compound of Formula I is between and including 50 and 95 wt.%, based on the mass of the at least one polymeric compound and the compound of Formula I, preferably between and including 55 and 90 wt.%, preferably between and including 60 and 90 wt.%, e.g. between and including 65 and 85 wt.%. In contrast, for the same amount of the at least one polymer usually about 75 wt.% of a common solvent like THF are needed for dissolution, meaning that the amount of the at least one polymeric compound is restricted to 25 wt.%. Thus, anLATER SUBMITTED SHEET100455W0019 enormous decrease of solvent is possible using the compound of Formula I and the polar organic solvent compared to currently used solvents. This is due to the high solvency power of the compound of Formula I, particularly the compound of Formula II, for the at least one polymeric compound, particularly a polyester. On the other hand, the amount of the compound of Formula I, particularly the compound of Formula II, should not be too high as due to the high solvency power losses of the latex particles in the removal step may be too high. Further, reduction of the amount of the compound of Formula I, particularly the compound of Formula II, also leads to a reduction of the total solvent amount, thus making the method cheaper and more environmental friendly. In addition, a decrease of the amount of the compound of Formula I, particularly the compound of Formula II, also mitigates the extent of a gelation phenomenon observed at the end of the emulsification step. Usually, the resulting emulsion starts to take a gellike consistency after a while, which is believed to be due to the presence of the compound of Formula I, particularly the compound of Formula II, which could also be confirmed in a control experiment wherein a latex is added to this compound. The mechanism of the gelation is still not well understood, though, but reduction of the amount of the compound of Formula I, particularly the compound of Formula II, mitigates this effect. Further mitigation is possible when carrying out the optional dilution step.While the solvent mixture in the solvent mixture comprises the polar organic solvent and the compound of Formula I, it is preferred that the solvent mixture contains the polar organic solvent and the compound of Formula I as main components and even more preferably only contains the polar organic solvent and the compound of Formula I. The solvent mixture preferably comprises the polar organic solvent and the compound of Formula I with at least 70 wt.%, more preferably with at least 90 wt.%, even more preferably with at least 95 wt.%, further preferably with at least 99 wt.%, based on the total amount of the solvent mixture. According to certain embodiments, the solvent mixture contains only the polar organic solvent and the compound of Formula I, apart from unavoidable impurities.The high solvency power of the compound of Formula I, particularly the compound of Formula II, further allows to dissolve all varieties of the at least one polymeric compound, particularly polyester, including amorphous and crystalline variants, e.g. even polymers with high crystallinity, which normally cannot be readily dissolved in theLATER SUBMITTED SHEET100455W00110 common solvents like THF and MEK. Thus, according to certain embodiments, the at least one polymeric compound can have a crystallinity between 20 and 100%, wherein the crystallinity can be e.g. determined using X-ray Diffraction (XRD) or Differential Scanning Calorimetry (DSC)measurement. Higher crystallinity of the at least one polymeric compound can lead to improved robustness in a printing process when the latex particles dispersion produced is used in a printing ink. However, it is also not excluded to use an amorphous polymeric compound and / or a compound with a lesser crystallinity.For dissolving the at least one polymeric compound, the temperature is not particularly restricted. However, the use of the compound of Formula I, particularly the compound of Formula II, allows the use of higher temperatures in the dissolution step as the compound has generally a higher boiling point and flash point than the commonly used solvents. Thus, the emulsification process can be carried out at higher temperatures, resulting in low viscosity, which reflects positively on the mixing efficiency. This, in turn, allows obtaining tunable latex particles dispersions that can comprise from very small particles with a diameter of 23nm, as e.g. measured by laser diffraction, respectively light scattering, e.g. using a zetasizer or accusizer® device, to higher diameters, while still allowing a very small size distribution with a polydispersity index (PDI) of down to ~ 0.05, the PDI also being determined e.g. by a zetasizer device.According to certain embodiments, the mixture of the at least one polymeric compound and the solvent mixture is heated prior to adding the water. This enables a fast dissolution. According to certain embodiments, the step of dissolving is carried out at a temperature of 30 to 90°C, preferably 40 to 85°C, further preferably 50 to 80°C, e.g. at 60 to 80°C, or also at 80 to 90°C. This is sufficiently higher than e.g. dissolution in THF, allowing also shorter dissolution times. According to certain embodiments, the dissolving step is carried out in 1 to 10h, preferably 2 to 7h, further preferably 2.5 to 5h, e.g. around 3h, which is a lot faster than dissolving in e.g. THF, which takes a time of about 24h. According to certain embodiments, dissolution of the at least one polymeric compound is carried out under stirring.Due to the dissolution at higher temperatures, furthermore the probability of formation of big chunks or clumps is drastically reduced or even avoided, which means that filtration of the latex formed can be omitted and reproducibility is also better. According to certainLATER SUBMITTED SHEET100455W00111 embodiments, no filtration is carried out in the present method of producing a latex particles dispersion.In the dissolution step, the at least one polymeric compound is not particularly restricted. According to certain embodiments, the at least one polymeric compound is chosen from the group consisting of polyesters, polyurethanes, polyepoxided, polyamided, polyethers, poly(meth)acrylates, polyolefins, polystyrene based polymers, polybutadiene-based polymers, fluorine containing polymers, polyvinyl acetate-based polymers, polyvinyl alcohol-based polymers, polyvinyl ester-based polymers, polyvinyl chloride-based polymers, polyacrylic acid based polymers, unsaturated carboxylic acidbased polymers and copolymers thereof. According to certain embodiments, the at least one polymeric compound is a polyester or a mixture of polyesters, particularly a polyester.According to certain embodiments, , in particular a polyester, the at least one polymeric compound has a Mwbetween and including 3000 and 50000 Da, preferably between and including 5000 and 2000 Da, as determined e.g. by gel permeation chromatography (GPC). preferably between and including 14000 and 20000. According to certain embodiments, the at least one polymeric compound has an acid value (AV) of between 5 and 50, e.g. between 7 and 20, although the acid value is not particularly restricted in general. The AV can be e.g. determined by titration titration with KOH solution.Further, the step of adding a base to the solution of the at least one polymeric compound is not particularly restricted. The step of adding a base enables selfstabilization of the at least one polymeric chains. According to certain embodiments, adding a base involves adding an aqueous solution of the base. Particularly, an aqueous solution of the base can be added. The base is not particularly restricted, but is preferably an inorganic base, particularly KOH, particularly in the form of an aqueous solution of KOH. The solution can be concentrated or diluted. The amount of the base can be calculated based on the desired neutralization percentage of the acid groups, which in turn will determine the particles size of the latex particles, and is thus not particularly restricted. While the neutralization using the base is not particularly restricted, a preferred neutralization is at least 30%. In this regard, it is noted that an AV of 20 for this invention is defined as using 20 mg of KOH per 1 g of resin, which thenLATER SUBMITTED SHEET100455W00112 would be 100% neutralization. However, this also allows for values beyond 100% neutralization, which is accompanied by a very slight decrease in particle sizes until a certain limit, e.g. 140%, where no difference is seen afterwards. The assumption is that hindered, shielded, difficult-to-reach acid groups in a sample of polymer dissolved in THF (which is the standard method to determine the AV of a polyester resin) are measured with a degree of neutralization higher than 100%.Furthermore, the step of adding water to the solution of the at least one polymeric compound to produce a latex particles dispersion in a ternary solvent mixture is not particularly restricted. The amount of water added is not limited and can e.g. depend on whether the base is added as aqueous solution or not. It is preferable that the water is added at increased temperature to facilitate formation of the latex particles, e.g. at a temperature of 30°C or more, preferably 50°C or more and 100°C or less, further preferably 60°C or more and 80°C or less, for example at around 70°C. A higher temperature achieves a higher mixing efficiency while keeping the viscosity low.Furthermore, it is preferred that the weight of water added is at least 60% (w / w) of the weight of the at least one polymeric compound. According to certain embodiments, the water is added dropwise to enable better mixing and formation of latex particles with homogeneous sides. For this purpose, it is also preferred to add the water while stirring the solution of the at least one polymeric compound.Furthermore, also the optional step of diluting the latex particles dispersion in a ternary solvent mixture is not particularly restricted. Dilution of the latex particles dispersion in a ternary solvent mixture can depend on the amount of water added before the step. Preferably, dilution is carried out with water. A dilution with water enables further stabilization of the latex particles and can mitigate the extent of the gelation phenomenon described above. While the dilution amount is not particularly restricted, a dilution of the unpurified latex in an amount of 4 to 6 times the volume of the latex formed (which e.g. contains 20% solid content, for example 200 g resin in 1 kg latex, which can be determined by evaporating solvent, e.g. water from the formed latex on a hot plate, e.g. at 200°C) achieves enhanced stability. Herein, the relation between the extent of dilution and the particles size is that when water, particularly cold water, is added at the end of the process to prevent gelation and to harden the particles spheres, the amount of water added to prevent gelation is dependent on the particles size. If theLATER SUBMITTED SHEET100455W00113 particles are very small, generally more water should be applied to dilute the system and prevent gelation compared to a case where big particles are present, as small particle latices are more susceptible to gelation than big ones. Hence, they require less dilution to prevent gelation. For example, for latices with 20-30nm particle size a dilution factor of 4 may be suitable. For lactices with 130nm particle size, dilution with a factor of 2-2.5 may be sufficient. Preferably, if carried out, a dilution is carried out immediately after addition of the water, particularly water at increased temperature, in the water addition step beforehand. The dilution is further preferably carried out with water at room temperature (about 20-25°C) to achieve cooling of the mixture.After the addition of water or the optional dilution step, if carried out, the mixture, i.e. the diluted latex particles dispersion in a ternary solvent mixture, can be cooled, before optional purification of the latex particles dispersion is carried out by essentially removing the polar organic solvent and the compound of Formula I from the (diluted) latex particles dispersion in the ternary solvent mixture to produce an aqueous latex particles dispersion. In this regard, the purification procedure can be seen as a simple concentration step as well.The preferable step of removal of the polar organic solvent and the compound of Formula I from the latex particles dispersion in the ternary solvent mixture to produce an aqueous latex particles dispersion can in the following and in the sense of the invention also be seen as a purification procedure, as thereafter a latex particles dispersion can be obtained that can be used as is, or from which the latex particles can be easily separated.Primarily, the removal / purification procedure can be seen as a simple concentration procedure of the latex particles, as the solvent for the at least one polymeric compound is removed. Removal of the compound of Formula I and the polar organic compound is not particularly restricted, and any suitable method can be carried out, e.g. involving dialysis, e.g. using a semipermeable membrane, diafiltration and / or decomposition. Thus, also different methods can be used in the removal step. As the compound of Formula I and the polar organic compound can usually form an azeotropic mixture, separating using distillation is generally avoided, also since the compound of Formula I can solve the at least one polymeric compound and thus extract latex particles, at least to some extent. Removal of the compound of Formula I and the polar organic solventLATER SUBMITTED SHEET100455W00114 can be carried out in a simpler way than in the usual method, where THF or MEK are evaporated at higher temperature in a time consuming, equipment-heavy step that needs additional cooling. As THF and MEK are problematic regarding health hazards and also with regard to flash point, the equipment also needs to be suitable for these hazards. Thus, the present method is advantageous also with regard to solvent removal. The same applies of course also to all steps before wherein the solvent is included, i.e. from the addition on. Additionally, the removal of the compound of Formula I and the polar organic solvent advantageously allows for increasing stability of the latex particles dispersion, e.g. under wide range of pH, and thereby improving the shelf life of the latex particles dispersion.The step of optionally separating the latex particles from the latex particles dispersion is not particularly restricted and can be carried out using any suitable way, e.g. using solidliquid separation methods like filtration, centrifugation, etc. As indicated above, this step does not have to be carried out in case a latex particles dispersion is intended as final product, e.g. for applying in a printing ink.Exemplary method of producing a latex particles dispersion is schematically shown in Figure 1.The method shown in Figure 1 , producing a latex particles dispersion, comprises a step 1 of dissolving at least one polymeric compound in a solvent mixture comprising a polar organic solvent and a compound of Formula I to produce a solution of the at least one polymeric compound, a step 2 of adding a base to the solution of the at least one polymeric compound, a step 3 of adding water to the solution of the at least one polymeric compound to produce a latex particles dispersion in a ternary solvent mixture, and a step 4 of essentially removing the polar organic solvent and the compound of Formula I from the latex particles dispersion in the ternary solvent mixture to produce an aqueous latex particles dispersion.In a second aspect, provided is a latex particles dispersion, produced by the method of of the present invention. The latex particles dispersion of the invention has the advantage that it has a narrow PDI with a tunable particle size, while at the same time no toxic solvent residue is preferably contained.LATER SUBMITTED SHEET100455W00115Particularly, the latex particles dispersion of the invention can be used in a dispersion, e.g. an aqueous dispersion. Thus, disclosed is also a dispersion comprising one or more the present latex particles dispersions in a sixth aspect. In the dispersion, a solvent is not particularly restricted, and one solvent like water can be used, or a mixture of solvents which are not particularly restricted. The dispersion is preferably an aqueous dispersion, though.The latex particles dispersion itself is not particularly restricted regarding the material and / or size of latex particles, and sizes can be tuned, as stated above, with the material depending on the at least one polymeric compound used in the production process. Thus, the resin of the latex particles can for example be based on a synthetic resin chosen from the group consisting of polyester resins, polyurethane resins, polyepoxy resins, polyamide resins, polyether resins, poly(meth)acrylic resins, acrylsilicone resins, fluorine-based resins, polyolefin resins, polystyrene-based resins, polybutadiene-based resins, polyvinyl acetate-based resins, polyvinyl alcohol-based resins, polyvinyl ester- based resins, polyvinyl chloride-based resins, polyacrylic acid based resins, unsaturated carboxylic acid-based resins, and copolymers such as styrene- acrylate copolymer resins, styrene-butadiene copolymer resins. The water-dispersible resin may be used in the form of a homopolymer, a copolymer or a composite resin. Particularly, the latex particles contains a polyester or is composed of a polyester, wherein the polyester is not particularly restricted. Particularly, the latex is a polyester latex. Examples of suitable polyesters are e.g. disclosed in US9964880A, paras.

[0034] -

[0044] ,

[0063] , US2016326338A, para.

[0031] , US9798255B, col. 2, I, 59 - col. 8, I. 3,US2015025174A, paras.

[0020] -

[0036] and EP1555295A, paras.

[0030] -

[0047] , incorporated herein by reference. Particularly the latex has polar groups, particularly on a surface thereof.Further disclosed is the use of the latex particles dispersion of the invention in a printing ink. The inventors found that the latex particles are particularly useful with regard to robustness of the printed image, achieving a higher robustness than with latex particles produced using a common organic solvent like THF or MEK. Due to the tunability of the particle size of the latex particles dispersions, they are particularly easy to handle and mix and to apply in varying printing inks. Exemplary printing inks are further described below.LATER SUBMITTED SHEET100455W00116A further aspect of the invention relates to a printing ink, comprising the present latex particles dispersion.The ink composition is not particularly limited and can be water-based, e.g. comprise a water-dispersible resin, a water-dispersible colorant, water, a cosolvent, a surfactant and optionally other additives. Preferably, the ink is water-based. In the ink, the amount of each component is not particularly limited as long as a printing ink is obtained. The ink comprises at least the latex particles dispersion, as described above, and optionally one or more pigments and / or colorants.Water-Dispersible ColorantA water-dispersible colorant may be a pigment or a mixture of pigments, a dye or a mixture of dyes or a mixture comprising pigments and dyes, as long as the colorant is water-dispersible. The pigment is not particularly limited and may be suitably selected in accordance with the intended use.Examples of the pigment usable include those commonly known without any limitation, and either a water-dispersible pigment or an oil-dispersible pigment is usable. For example, an organic pigment such as an insoluble pigment or a lake pigment, as well as an inorganic pigment such as carbon black, is preferably usable.Examples of the insoluble pigments are not particularly limited, but preferred are an azo, azomethine, methine, diphenylmethane, triphenylmethane, quinacridone, anthraquinone, perylene, indigo, quinophthalone, isoindolinone, isoindoline, azine, oxazine, thiazine, dioxazine, thiazole, phthalocyanine, or diketopyrrolopyrrole dye.For example, inorganic pigments and organic pigments for black and color inks are exemplified. These pigments may be used alone or in combination. As the inorganic pigments, it is possible to use carbon blacks produced by a known method such as a contact method, furnace method and thermal method, in addition to titanium oxide, iron oxide, calcium carbonate, barium sulfate, aluminum hydroxide, barium yellow, cadmium red and chrome yellow.As the organic pigments, it is possible to use azo pigments (including azo lake, insoluble azo pigments, condensed pigments, chelate azo pigments and the like), polycyclicLATER SUBMITTED SHEET100455W00117 pigments (e.g., phthalocyanine pigments, perylene pigments, perynone pigments, anthraquinone pigments, quinacridone pigments, dioxazine pigments, indigo pigments, thioindigo pigments, isoindolinone pigments, and quinophthalone pigments), dye chelates (e.g., basic dye type chelates, and acidic dye type chelates), nitro pigments, nitroso pigments, aniline black. Among these, particularly, pigments having high affinity with water are preferably used.Specific pigments which are preferably usable are listed below.Examples of pigments for magenta or red include: C.l. Pigment Red 1 , C.l. Pigment Red 2, C.l. Pigment Red 3, C.l. Pigment Red 5, C.l. Pigment Red 6, C.l. Pigment Red 7, C.l. Pigment Red 15, C.l. Pigment Red 16, C.l. Pigment Red 17, C.l. Pigment Red 22, C.l. Pigment Red 23, C.l. Pigment Red 31 , C.l. Pigment Red 38, C.l. Pigment Red 48:1 , C.l. Pigment Red 48:2 (Permanent Red 2B(Ca)), C.l. Pigment Red 48:3, C.l. Pigment Red 48:4, C.l. Pigment Red 49:1 , C.l. Pigment Red 52:2; C.l. Pigment Red 53:1 , C.l.Pigment Red 57:1 (Brilliant Carmine 6B), C.l. Pigment Red 60:1 , C.l. Pigment Red 63:1 , C.l. Pigment Red 64:1 , C.l. Pigment Red 81. C.l. Pigment Red 83, C.l. Pigment Red 88, C.l. Pigment Red 101 (colcothar), C.l. Pigment Red 104, C.l. Pigment Red 106, C.l.Pigment Red 108 (Cadmium Red), C.l. Pigment Red 112, C.l. Pigment Red 114, C.l.Pigment Red 122 (Quinacridone Magenta), C.l. Pigment Red 123, C.l. Pigment Red 139, C.l. Pigment Red 44, C.l. Pigment Red 146, C.l. Pigment Red 149, C.l. Pigment Red 166, C.l. Pigment Red 168, C.l. Pigment Red 170, C.l. Pigment Red 172, C.l.Pigment Red 177, C.l. Pigment Red 178, C.l. Pigment Red 179, C.l. Pigment Red 185, C.l. Pigment Red 190, C.l. Pigment Red 193, C.l. Pigment Red 209, C.l. Pigment Red 219 and C.l. Pigment Red 222, C.l. Pigment Violet 1 (Rhodamine Lake), C.L Pigment Violet 3, C.L Pigment Violet 5:1 , C.L Pigment Violet 16, C.L Pigment Violet 19, C.L Pigment Violet 23 and C.L Pigment Violet 38.Examples of pigments for orange or yellow include: C.L Pigment Yellow 1 , C.L Pigment Yellow 3, C.L Pigment Yellow 12, C.L Pigment Yellow 13, C.L Pigment Yellow 14, C.L Pigment Yellow 15, C.L Pigment Yellow 15:3, C.L Pigment Yellow 17, C.L Pigment Yellow 24, C.L Pigment Yellow 34, C.L Pigment Yellow 35, C.L Pigment Yellow 37, C.L Pigment Yellow 42 (yellow iron oxides), C.L Pigment Yellow 53, C.L Pigment Yellow 55, C.L Pigment Yellow 74, C.L Pigment Yellow 81 , C.L Pigment Yellow 83, C.L Pigment Yellow 93, C.L Pigment Yellow 94, C.L Pigment Yellow 95, C.L Pigment Yellow 97, C.LLATER SUBMITTED SHEET 100455W00118Pigment Yellow 98, C.l. Pigment Yellow 100, C.l. Pigment Yellow 101 , C.l. Pigment Yellow 104, C.l. Pigment Yellow 408, C.l. Pigment Yellow 109, C.l. Pigment Yellow 110, C.l. Pigment Yellow 117, C.l. Pigment Yellow 120, C.l. Pigment Yellow 128, C.l.Pigment Yellow 138, C.l. Pigment Yellow 150, C.l. Pigment Yellow 151 , C.l. Pigment Yellow 153 and C.l. Pigment Yellow 183; C.l. Pigment Orange 5, C.l. Pigment Orange 13, C.l. Pigment Orange 16, C.l. Pigment Orange 17, C.l. Pigment Orange 31 , C.l.Pigment Orange 34, C.l. Pigment Orange 36, C.l. Pigment Orange 43, and C.l. Pigment Orange 51.Examples of pigments for green or cyan include: C.l. Pigment Blue 1 , C.l. Pigment Blue 2, C.l. Pigment Blue 15, C.l. Pigment Blue 15:1 , C.l. Pigment Blue 15:2, C.l. Pigment Blue 15:3 (Phthalocyanine Blue), C.l. Pigment Blue 16, C.l. Pigment Blue 17:1 , C.l.Pigment Blue 56, C.l. Pigment Blue 60, C.l. Pigment Blue 63, C.l. Pigment Green 1 , C.l. Pigment Green 4, C.l. Pigment Green 7, C.l. Pigment Green 8, C.l. Pigment Green 10, C.l. Pigment Green 17, C.l. Pigment Green 18 and C.l. Pigment Green 36.In addition to the above pigments, when red, green, blue or intermediate colors are required, it is preferable that the following pigments are employed individually or in combination thereof. Examples of employable pigments include: C.l. Pigment Red 209, 224, 177, and 194, C.l. Pigment Orange 43, C.l. Vat Violet 3, C.l. Pigment Violet 19, 23, and 37, C.l. Pigment Green 36, and 7, C.l. Pigment Blue 15:6.Further, examples of pigments for black include: C.l. Pigment Black 1 , C.l. Pigment Black 6, C.l. Pigment Black 7 and C.l. Pigment Black 11 . Specific examples of pigments for black color ink usable in the present invention include carbon blacks (e.g., furnace black, lamp black, acetylene black, and channel black); (C.l. Pigment Black 7) or metalbased pigments (e.g., copper, iron (C.l. Pigment Black 11), and titanium oxide; and organic pigments (e.g., aniline black (C.l. Pigment Black 1).SolventWater is cited as an environmentally friendly and hence desirable solvent.CosolventAs a cosolvent of the ink, e.g. for the purposes of improving the ejection property of the ink or adjusting the ink physical properties, the ink preferably contains a water solubleLATER SUBMITTED SHEET100455W00119 organic solvent in addition to water. There is no restriction in particular in the type of the water soluble organic solvent. Also, more than one cosolvent can be used in the ink used in the present invention. As stated above, also a decomposition product of the compound of Formula I, particularly the compound of Formula II, can act as cosolvent as well.Examples of the water-soluble organic solvent include polyhydric alcohols, polyhydric alcohol alkyl ethers, polyhydric alcohol aryl ethers, nitrogen-containing heterocyclic compounds, amides, amines, ammonium compounds, sulfur-containing compounds, propylene carbonate, and ethylene carbonate.Examples of the solvent include: glycerin (also termed glycerol), propylene glycol, dipropylene glycol, tripropylene glycol, tetrapropylene glycol, polypropylene glycol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols preferably having a molecular weight of between 200 gram / mol and 1000 gram / mol (e.g. PEG 200, PEG 400, PEG 600, PEG 800, PEG 1000), glycerol ethoxylate, petaerythritol ethoxylate, polyethylene glycol (di)methylethers preferably having a molecular weight of between 200 gram / mol and 1000 gram / mol, tri-methylol- propane, diglycerol (diglycerin), trimethylglycine (betaine), N-methylmorpholine N-oxide, decaglyserol, 1 ,4-butanediol, 1 ,3-butanediol, 1 ,2,6-hexanetriol, 2-pyrrolidinone, dimethylimidazolidinone, ethylene glycol mono-butyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-propyl ether, diethylene glycol mono-butyl ether, triethylene glycol monomethyl ether, triethylene glycol monoethyl ether, triethylene glycol mono-propyl ether, triethylene glycol mono-butyl ether, tetraethylene glycol monomethyl ether, tetraethylene glycol monoethyl ether, propylene glycol mono-butyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, dipropylene glycol monopropyl ether, diethylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monoethyl ether, tripropylene glycol monopropyl ether, tripropylene glycol monobutyl ether, tetrapropylene glycol monomethyl ether, diethylene glycol diethyl ether, diethylene glycol dibutyl ether, triethylene glycol diethyl ether, triethylene glycol dibutyl ether, dipropylene glycol dibutyl ether, tri propylene glycol dibutyl ether, 3-methyl 2,4-pentanediol, diethylene-glycol-monoethyl ether acetate, 1 ,2-hexanediol, 1 ,2- pentanediol and 1 ,2-butanediol.LATER SUBMITTED SHEET100455W00120SurfactantsIt is preferable that the ink contains at least one surfactant in order to improve an ink ejection property and / or the wettability of the surface of a recording medium, and the image density and color saturation of the image formed and reducing white spots therein. Using surfactants, the surface tension, i.e. the dynamic surface tension as well as the static surface tension, can be adjusted.Examples of surfactants are not specifically limited. The following can be cited.Examples of the surfactant include nonionic surfactants, cationic surfactants, anionic surfactants, amphoteric surfactants, in particular betaine surfactants, and silicone surfactants.Examples of a cationic surfactant include: aliphatic amine salts, aliphatic quarternary ammonium salts, benzalkonium salts, benzethonium chloride, pyridinium salts, imidazolinium salts.Examples of an anionic surfactant include: polyoxyethylene alkylether acetic acid salts, dodecylbenzene sulfonic acid salts, lauric acid salts, and salts of polyoxyethylene alkylether sulfate, an aliphatic acid soap, an N-acyl-N-methyl glycin salt, an N-acyl-N- methyl-p-alanine salt, an N-acylglutamate, an acylated peptide, an alkylsulfonic acid salt, an alkylbezenesulfonic acid salt, an alkylnaphthalenesulfonic acid salt, a dialkylsulfo succinate (e.g. sodium dioctyl sulfosuccinate (DSS); alternative names: docusate sodium, Aerosol OT and AOT), alkylsulfo acetate, a-olefin sulfonate, N-acyl- methyl taurine, a sulfonated oil, a higher alcohol sulfate salt, a secondary higher alcohol sulfate salt, an alkyl ether sulfate, a secondary higher alcohol ethoxysulfate, a polyoxyethylene alkylphenyl ether sulfate, a monoglysulfate, an aliphatic acid alkylolamido sulfate salt, an alkyl ether phosphate salt and an alkyl phosphate salt.Examples of an amphoteric surfactant include: a carboxybetaine type, a sulfobetaine type, an aminocarboxylate salt and an imidazolium betaine.Examples of a nonionic surfactant include: polyoxyethylene alkylether, polyoxypropylene polyoxyethylene alkylether, a polyoxyethylene secondary alcohol ether, a polyoxyethylene alkylphenyl ether, a polyoxyethylene sterol ether, aLATER SUBMITTED SHEET 100455W00121 polyoxyethylenelanolin derivative polyoxyethylene polyoxypropylene alkyl ether, polyoxyethylene alkylester, a polyoxyethyleneglycerine aliphatic acid ester, a polyoxyethylene castor oil, a hydrogenated castor oil, a polyoxyethylene sorbitol aliphatic acid ester, a polyethylene glycols aliphatic acid ester, an aliphatic acid monoglyceride, a polyglycerine aliphatic acid ester, a sorbitan aliphatic acid ester, polyoxyethylene sorbitan aliphatic ester, a propylene glycol aliphatic acid ester, a cane sugar aliphatic acid ester, an aliphatic acid alkanol amide, polyoxyethylene alkylamide, a polyoxyethylene aliphatic acid amide, a polyoxyethylene alkylamine, an alkylamine oxide, an acetyleneglycol, an ethoxylated acetylene glycol, acetylene alcohol.Examples of the silicone surfactant include side-chain-modified polydimethylsiloxane, both-ends-modified polydimethylsiloxane, one-end-modified polydimethylsiloxane, and side-chain / both-ends-modified polydimethylsiloxane. Polyether-modified silicone surfactants having, as a modified group, a polyoxyethylene group or a polyoxyethylene polyoxypropylene group are particularly preferable because they exhibit excellent physical properties as water-based surfactants. The silicone surfactant may be suitably synthesized or commercial products may be used. Commercial products are readily available from BYK Chemie GmbH, Shin-Etsu Chemical Co., Ltd., TORAY Dow Corning Silicone Co., Ltd., Nihon Emulsion Co., Ltd., Kyoeisha Chemical Co., Ltd., or the like.The polyether-modified silicone surfactant is not particularly limited and may be suitably selected in accordance with the intended use. As the polyether-modified silicone surfactant, commercial products may be used. Examples of the commercial products include KF-618, KF-642 and KF-643 (produced by Shin-Etsu Chemical Co., Ltd.);EMALEX-SS-5602 and SS- 1906EX (produced by Nihon Emulsion Co., Ltd.); FZ-2105, FZ-2118, FZ-2154, FZ-2161 , FZ-2162, FZ-2163 and FZ-2164 (produced by TORAY Dow Corning Silicone Co., Ltd.); and BYK-33, BYK 331 , BYK 341 , BYK 348, BYK 349, BYK 3455, BYK-387 (produced by BYK Chemie GmbH); Tegowet 240, Tegowet 245, Tegowet 250, Tegowet 260 (produced by Evonik); Silwet L-77 (produced by Sabie).All surfactants mentioned in this section may be used solely, or they may be used in combination.AdditivesLATER SUBMITTED SHEET100455W00122The ink composition may optionally further contain additives like biocides or a penetrant, which is a compound that promotes absorption of the ink composition in the print medium, and the additives are not particularly limited and comprise those usually used in inks.Furthermore disclosed is a printing method, comprising: applying a primer liquid on at least one surface of a recording medium; and printing an image with at least one printing ink comprising at least one latex particles dispersion on the surface of the recording medium on which the primer has been applied; wherein the at least one latex particles dispersion comprises the latex particles dispersion of the invention, respectively produced by the method of producing the latex particles dispersion of the invention.Primer applicationIn the present printing method, applying a primer on at least one surface of a recording medium is not particularly restricted.To improve the spreading and pinning (i.e. fixation of pigments and / or water-dispersed polymer particles) of the ink on the recording medium, in particular on slow absorbing media, such as machine coated media, the recording medium is pre-treated, i.e. treated prior to printing an image on the medium, with the primer. The pre-treatment step comprises the application of the primer and may further comprise one or more of the following: preheating of the receiving medium to enhance spreading of the used ink on the receiving medium and / or to enhance absorption of the used ink into the receiving medium; corona or plasma treatment.Primer pre-treatmentAs an application way of the primer, any conventionally known methods can be used.Specific examples of an application way include: a roller coating, an ink-jet application, a curtain coating and a spray coating. There is no specific restriction in the number of times with which the primer is applied. It may be applied at one time, or it may be applied in two times or more. Application in two times or more may be preferable, sinceLATER SUBMITTED SHEET100455W00123 cockling of the coated printing paper can be prevented and the film formed by the primer will produce a uniform dry surface having no wrinkle by applying in 2 steps or more.Especially a roller coating method can be used because this coating method does not need to take into consideration ejection properties and it can apply the primer homogeneously to a recording medium. In addition, the amount of the applied primer with a roller or with other means to a recording medium can be suitably adjusted by controlling: the physical properties of the primer; and the contact pressure of a roller in a roller coater to the recording medium and the rotational speed of a roller in a roller coater which is used for a coater of the primer. As an application area of the primer, it may be possible to apply only to the printed portion, or to the entire surface of both the printed portion and the non-printed portion. However, when the primer is applied only to the printed portion, unevenness may occur between the application area and a nonapplication area caused by swelling of cellulose contained in the coated printing paper with water in the primer followed by drying. Then, from the viewpoint of drying uniformly, it is preferable to apply the primer to the entire surface of a recording medium, and roller coating can be preferably used as a coating method to the whole surface. The primer may be an aqueous primer, as described further below.Corona or plasma treatmentCorona or plasma treatment may be used as a pre-treatment step by exposing a sheet of a recording medium to corona discharge or plasma treatment. In particular when used on media like polyethylene (PE) films, polypropylene (PP) films, polyetyleneterephtalate (PET) films and machine coated media, the adhesion and spreading of the ink can be improved by increasing the surface energy of the media. With machine coated media, the absorption of water can be promoted which may induce faster fixation of the image and less puddling on the receiving medium. Surface properties of the receiving medium may be tuned by using different gases or gas mixtures as medium in the corona or plasma treatment. Examples are air, oxygen, nitrogen, carbondioxide, methane, fluorine gas, argon, neon and mixtures thereof. Corona treatment in air is most preferred.According to certain embodiments, the primer is essentially dried on the recording medium before the image is printed. An essential drying can be achieved if less than 5 wt.% of the solvents, e.g. water and / or cosolvents, of the primer remain on the recordingLATER SUBMITTED SHEET100455W00124 medium after drying and prior to printing the printing image, e.g. less than 2 wt.% or less than 1 wt.% of the solvents. According to certain embodiments, the primer is dried on the recording medium before the (first) ink for printing the printing image is applied. The drying can be carried out in any way and is not particularly limited. For example, drying can be achieved by heaters and / or radiators, e.g. IR radiators, applied in a printing apparatus at and / or after an application unit for the primer.Recordinq / Receivinq mediaSuitable recording media for use in a printing process using an ink or set of inks (e.g.Cyan, Magenta, Yellow and blacK, CMYK; OVG; etc.) according to the present invention are not particularly limited to any type. The receiving medium may be suitably selected depending on the intended application.Suitable receiving media may range from strongly water absorbing media such as plain paper to non-water-absorbing media such as plastic sheets (for example PE, PP, PVC and PET films). To optimize print quality, inkjet coated media are known, which media comprise a highly water absorbing coating.Further exemplified are Machine Coated (MC) media (also known as offset coated media) and glossy (coated) media. MC media are designed for use in conventional printing processes, for example offset printing and show good absorption characteristics with respect to solvents used in inks used in such printing processes, which are usually organic solvents. MC and glossy media show inferior absorption behavior with respect to water (worse than plain paper, better than plastic sheets), and hence aqueous inks.Machine coated or offset coated media comprise a base layer and a coating layer.The base layer may be a sheet of paper mainly made of wood fibers or a non-woven fabric material comprising wood fibers combined with synthetic fibers. The base layer may be made of wood pulp or recycled paper pulp and may be bleached.As an internal filler for the base, a conventional white pigment may be used. For example, the following substances may be used as a white pigment: an inorganic pigment such as precipitated calcium carbonate, heavy calcium carbonate, kaolin, clay, talc, calcium sulfate, barium sulfate, titanium dioxide, zinc oxide, zinc sulfide, zincLATER SUBMITTED SHEET100455W00125 carbonate, satin white, aluminum silicate, diatomaceous earth, calcium silicate, magnesium silicate, synthetic silica, aluminum hydroxide, alumina, lithophone, zeolite, magnesium carbonate, or magnesium hydrate; and an organic pigment such as styrene plastic pigment, acrylic plastic pigment, polyethylene, microcapsule, urea resin, or melamine resin. These may be used alone or in combination.As an internal sizing agent used when producing the base, a neutral rosin size used for neutral papermaking, alkenyl succinic anhydride (ASA), alkyl ketene dimer (AKD), or a petroleum resin size may be used. Especially, a neutral rosin size and alkenyl succinic anhydride are preferable. Alkyl ketene dimer has a high sizing effect and therefore provides an enough sizing effect with a small amount. However, since alkyl ketene dimer reduces the friction coefficient of the surface of recording paper (medium), recording paper made using alkyl ketene dimer may cause a slip when being conveyed in an inkjet recording apparatus.The thickness of the base is not particularly limited and may be suitably selected in accordance with the intended use. It is, however, preferably 50 pm to 300 pm. The basis weight of the base is preferably 45 g / m2to 290 g / m2.The coating layer may comprise a (white) pigment, a binder and may further contain a surfactant and other components as required.An inorganic pigment or a combination of an inorganic pigment and an organic pigment can be used as the pigment.Examples of the inorganic pigment include kaolin, talc, calcium bicarbonate, light calcium carbonate, calcium sulfite, amorphous silica, titanium white, magnesium carbonate, titanium dioxide, aluminum hydroxide, calcium hydroxide, magnesium hydroxide, zinc hydroxide and chlorite. Among these, kaolin is particularly preferable due to its superior glossability. The addition amount of the kaolin is preferably 50 parts by mass or more with respect to 100 parts of the binder in the coating layer. When the amount of kaolin is less than 50 parts by mass, adequate effects are unable to be obtained with respect to glossiness.Examples of the organic pigment include (aqueous) dispersions of, for example,LATER SUBMITTED SHEET100455W00126 styrene-acrylic copolymer particles, styrene-butadiene copolymer particles, polystyrene particles or polyethylene particles. These organic pigments may be used in combination. The addition amount of the organic pigment is preferably 2 parts by mass to 20 parts by mass with respect to 100 parts by mass of the total amount of the pigment in the coating layer. Since the organic pigment has superior glossability and the specific gravity thereof is small in comparison with inorganic pigment, it allows the obtaining of a coating layer having high bulk, high gloss and satisfactory surface coatability.An aqueous resin may be used for the binder. At least one of a water-soluble resin and / or a water-dispersible resin may be used for the aqueous resin.There are no particular limitations on the water-soluble resin, the water-soluble resin can be suitably selected according to the intended use. Examples thereof include polyvinyl alcohol and polyvinyl alcohol modification products such as anion-modified polyvinyl alcohol, cation-modified polyvinyl alcohol or acetal-modified polyvinyl alcohol; polyurethane; polyvinyl pyrrolidone and polyvinyl pyrrolidone modification products such as copolymers of polyvinyl pyrrolidone and vinyl acetate, copolymers of vinyl pyrrolidone and dimethylaminoethyl methacrylate, copolymers of quaternized vinyl pyrrolidone and dimethylaminoethyl methacrylate or copolymers of vinyl pyrrolidone and methacrylamide propyl trimethyl ammonium chloride; celluloses such as carboxymethyl cellulose, hydroxyethyl cellulose or hydroxypropyl cellulose; cellulose modification products such as cationized hydroxyethyl cellulose; synthetic resins such as polyester, polyacrylic acid (ester), melamine resin or modification products thereof or copolymers of polyester and polyurethane; and poly(meth)acrylic acid, poly(meth)acrylamide, oxidized starch, phosphoric acid-esterified starch, self-modifying starch, cationized starch, various types of modified starch, polyethylene oxide, sodium polyacrylate and sodium arginate. These water-soluble resins may be used alone or in combination.There are no particular limitations on the water-dispersible resin, a water-dispersible resin can be suitably selected in accordance with the intended use, and examples thereof include polyvinyl acetate, ethylene-vinyl acetate copolymers, polystyrene, styrene-(meth)acrylic acid ester copolymers, (meth)acrylic acid ester copolymers, vinyl acetate-(meth)acrylic acid (ester) copolymers, styrene-butadiene copolymers, ethylenepropylene copolymers, polyvinyl ether and silicone-acrylic copolymers. In addition, a crosslinking agent such as methylolated melamine, methylolated urea, methylolatedLATER SUBMITTED SHEET100455W00127 hydroxypropylene urea or isocyanate may also be contained, and the water-dispersible resin may self-crosslink with a copolymer containing a unit such as N- methylolacrylamide. A plurality of these aqueous resins can also be used simultaneously.The addition amount of the aqueous resin is preferably 2 parts by mass to 100 parts by mass and more preferably 3 parts by mass to 50 parts by mass with respect to 100 parts by mass of the pigment. The amount of the aqueous resin is determined so that the liquid absorption properties of the recording media are within a desired range.Primer (also called pre-treatment liquid')The primer is not particularly restricted. The primer is particularly an aqueous primer, i.e. contains water, usually contains at least one salt, and may further contain at least one organic acid, e.g. dissolved in the water, one or more cosolvents, one or more surfactants, etc.The at least one salt comprised in the primer is not particularly restricted. Furthermore, it is also not excluded that more than one salt is contained. However, according to certain embodiments only one salt is contained in the primer. In the primer, the at least one salt, particularly multivalent cationic salt is present to destabilize color pigments (normally having a negative charge at the pH of usual inks) during the printing process, thus leading to good printing properties. The at least one multivalent cationic salt is not particularly limited, and those usually used in primers for ink-jet printing can usually be applied. For example, useful cationic salts include water-soluble salts of magnesium, calcium, strontium, barium aluminum, copper, iron, nickel and zinc, particularly magnesium and calcium, particularly magnesium. According to certain embodiments, the primer comprises at least one multivalent cationic salt, particularly of magnesium, like magnesium sulfate, e.g. as heptahydrate. According to certain embodiments, the at least one salt is a magnesium salt.Examples of organic acids that can be used in the primer include acetic acid, malonic acid, arginic acid, citric acid, amino acids like glycine and glutamic acid, succinic acid, tartaric acid, oxalic acid, fumaric acid, phthalic acid, maleic acid, and malic acid.As stated above, the primer can further comprise at least one cosolvent and / or at leastLATER SUBMITTED SHEET100455W00128 one surfactant, e.g. for facilitating jetting. These are not particularly limited and can comprise those that are normally used in primers. Particularly, the co-solvent is compatible and miscible with water. Further, the surfactant is preferably water-soluble. According to certain embodiments, the co-solvent and / or surfactant can comprise those that are usually used in ink-jet printing inks, like the ones described below with regard to the ink used in the present printing method. An exemplary useful co-solvent comprises for example glycerol or other solvents that can help provide sufficient viscosity and / or surface tension to the primer so that it can spread evenly on the recording medium. Additionally, the one or more surfactant(s) can further help adjust the viscosity and / or surface tension of the primer.Additionally, also further components can be comprised in the primer, e.g. additives that are usually used in pre-treatment, respectively priming, liquids in ink-jet printing, for example pH regulators to prevent corrosion of the printing equipment, amine additive, biocides, etc.It is not excluded in the present invention that the primer is separated into two or more different portions.Printing stepThe step of printing an image with at least one ink on the surface of the recording medium on which the primer has been applied is also not particularly restricted. As stated above, it is preferred that the recording medium on which the primer is applied is dried before the at least one ink is applied. While only an image with one ink may be applied, an image with at least two inks, e.g. two, three, four, five, six and / or seven inks can be printed on the recording medium.Image formation may be performed in such a manner that, employing an inkjet printer loaded with inkjet inks, ink droplets are ejected from inkjet heads based on the digital signals onto a recording medium.Although both single pass inkjet printing and multi pass (i.e. scanning) inkjet printing may be used for image formation, single pass inkjet printing is preferably used since it is effective to perform high-speed printing. Single pass inkjet printing is an inkjet recording method with which ink droplets are deposited onto the receiving medium to form allLATER SUBMITTED SHEET 100455W00129 pixels of the image by a single passage of a recording medium underneath an inkjet marking module. In image formation by ejecting an ink, an inkjet head (i.e. printhead) employed may be either an on-demand type or a continuous type inkjet head.Optionally, the image formation may be carried out while the recording medium is temperature controlled. For this purpose, a temperature control device may be arranged to control the temperature of the surface of a transportation mechanism (e.g. belt or drum). The temperature control device may be used to control the surface temperature of the recording medium, for example in the range of 30°C to 60°C. The temperature control device may comprise heaters, such as radiation heaters, and a cooling means, for example a cold blast, in order to control the surface temperature of the receiving medium within said range.Drying and fixingAfter an image has been formed on the receiving medium, the prints usually have to be dried and the image has to be fixed onto the receiving medium. Drying comprises generally the evaporation of solvents, in particular those solvents that have poor absorption characteristics with respect to the selected recording medium.A drying and fixing unit for this purpose may comprise a heater, for example a radiation heater. After an image has been formed, the print is heated such that solvents present in the printed image, to a large extent water, evaporate. The speed of evaporation and hence drying may be enhanced by increasing the air refresh rate in the drying and fixing. Simultaneously, film formation of the ink occurs, because the prints are heated to a temperature above the minimum film formation temperature (MFT).Application of varnishA varnish may be applied on the printed image, and the step is not particularly restricted. It can be jetted onto the recording medium with the printed image, but can also be jetted onto the whole recording medium so that an even gloss can be obtained. If primer is only applied to regions that are printed on, it is also possible to only apply the varnish on the printed areas. The means for applying, e.g. rod coating, roller coating, jetting, etc., are not particularly restricted.VarnishLATER SUBMITTED SHEET100455W00130In the present ink-jet printing method, the varnish is not restricted, and any varnish for increasing gloss and / or robustness may be used, particularly for increasing gloss.The varnish particularly forms a transparent layer on the printed recording medium. As varnish, an aqueous solution comprising components capable of forming a transparent protective layer over a recording medium (e.g. a water-dispersible resin, a surfactant, water, and additives as required) is preferably used. The varnish thus is preferably water-based, and preferably contains a latex emulsion / water-dispersible resin emulsion, an alkali soluble polymer, or a combination of both. Preferably, these carry carboxylic acid groups. The water-dispersible resin comprised in the varnish preferably has a glass transition temperature (Tg) of -30°C or higher, and more preferably in the range of -20°C to 100°C. The minimum film forming temperature (MFT) of the water-dispersible resin is preferably 50°C or lower, and more preferably 35°C or lower. The water-dispersible resin may be radiation curable to improve the glossiness and fixability of the image. The water-dispersible resin and / or alkali soluble polymer can react with residual primer salt components, particularly when they carry acid groups, particularly carboxylic acid groups, which can lead to destabilizing these particles or creating a gel of the soluble polymer part, leading to roughness differences and / or reduced film-forming properties, causing gloss level reduction. Using the neutralizing liquid, reaction of salt components of the primer with varnish components can be reduced or even prevented. This provides an improved freedom of choice of a varnish composition.As the water-dispersible resin, for example, an acrylic resin, a styrene-acrylic resin, a urethane resin, an acryl-silicone resin, a fluorine resin and the like may be used. The water-dispersible resin can be suitably selected from the same materials as that used for the inkjet ink. The amount of the water-dispersible resin contained, as a solid content, in the protective layer is preferably 1 wt.% to 50 wt.%. The surfactant comprised in the post-treatment liquid is not particularly limited and may be suitably selected from those used in the inkjet ink. Examples of the other components of the post-treatment liquid include antifungal agents, antifoaming agents, and pH adjustors.Further stepsFurther steps can be carried out in the present ink-jet printing method.For example, a drying step may be carried out after varnish application. While dryingLATER SUBMITTED SHEET100455W00131 steps may be implemented between each application step (primer - ink - varnish), wet- in-wet processes are also covered in the present method, e.g. no drying takes place between primer and ink application and / or between ink and varnish application.According to certain embodiments, a drying step is carried out at least before application of the varnish.The above embodiments can be combined arbitrarily, if appropriate. Further possible embodiments and implementations of the invention comprise also combinations of features not explicitly mentioned in the foregoing or in the following with regard to the Examples of the invention. Particularly, a person skilled in the art will also add individual aspects as improvements or additions to the respective basic form of the invention.EXAMPLESThe present invention will now be described in detail with reference to several examples thereof. However, these examples are illustrative and do not limit the scope of the invention.Example 1 : Production of latex particlesLatex particles dispersion was prepared as follows. A solvent mixture of 3 g 1 ,2- butylene carbonate and 8 g 1 -propanol was mixed with 5 g of a polyester having a weight average molecular weight Mwof 7.5 kDa and an acid value of 7.5. Herein, the acid value was measured through titrating the dissolved resin in THF with KOH solution, in presence of phenolphthalein indicator.The mixture was heated up to 40-50°C and stirred till the polymer is completely dissolved, which was done within 3-4 hours, a time that was also observed for other polyesters described below. Here it is of note that the boiling point of 1 ,2-butylene carbonate is about 251 °C, which drops significantly when mixed with 1 -propanol, forming an azeotropic mixture. Yet, the boiling point is still well above 100°C, which allows using heat to expedite the dissolution of the polymer. In this process with 1 ,2- butylene carbonate as solvent, it takes merely three hours to completely dissolve the polymer in a mixture of 1 ,2-butylene carbonate and 1 -propanol at 45-50°C (e.g. dissolving 250 g of polymer in a total amount of 550 g solvent), where it takes usually one day with equal amounts of THF (here e.g. dissolving 250 g of polymer in 750 g of THF). At 80 to 90 °C, even faster dissolution is possible with 1 ,2 butylene carbonate.LATER SUBMITTED SHEET100455W00132Another advantage of the high boiling point is the enhanced mixing efficiency. The success of emulsifying a substance in a medium depends on the efficiency of mixing. Here, increasing the temperature can tune particle size and distribution.Then, an aqueous solution of KOH (here concentrated at 47 wt.%, can also be diluted at 2.35 wt.% as this does not have an influence on the process if the amount of water is kept constant) is added. The amount of the KOH is calculated based on the desired neutralization percentage of the acid groups, which in turn will determine the particles size. In this instance, the degree of neutralization was set at 100%, based on the calculated amount needed. For example, if the acid value is 7.5 mg KOH / 1g polymer, and 100g resin are used, 7.5x100=750mg KOH are needed. If 750mg KOH are added, this corresponds to a 100% neutralization degree.After the addition of the aqueous KOH, around 15 mL hot water are added dropwise. At the beginning of the addition, the solution remains transparent, and then starts to become cloudy which indicates the formation of a latex particles dispersion. It is worth mentioning that the viscosity increases slightly, and then it drops suddenly at the end of the first water addition.The formed hot latex particles dispersion is diluted with room temperature (20 - 25°C) / cold water to 4-6 times the volume of the latex (which contains 20% solid content). This step is carried out immediately. The extent of dilution depends mainly on the particles size to be produced; the bigger the particles, the less dilution is needed. After the dilution, the cooled down latex is processed in the next step which includes purification.Primarily, the purification procedure needed here is a simple concentration. Here, removal of the 1 ,2-butylene carbonate and 1 -propanol is carried out using dialysis using cellulose dialysis tubing. The obtained latex particles dispersion is placed in the dialysis tubing and dialyzed against demineralized water for a day with changing the water a couple of times, here 3-4 times. Then the swollen dialysis tubing is hung in air to let some of the water present in the obtained aqueous latex particles dispersion evaporate as a mean of concentrating the latex. Eventually, the dialysis tubing is emptied and the aqueous latex particles dispersion is filtered to remove any solid particles to yield purified latex particles dispersion. For larger scale samples with 100 g resin or more aLATER SUBMITTED SHEET100455W00133 dialysis set-up with either columns plate filters is applied. The semipermeable membranes for dialysis are made of polyethersulfon PES, with different pores sizes, or from modified cellulose, which is compatible with 1 ,2-butylene carbonate and 1- propanol.To explain the purification / removal step it is important to understand the approach behind the latex preparation process. The 1 ,2-butylene carbonate is immiscible with water, and to make an aqueous based latex it is thus necessary to have a solvent that is miscible with water. Fortunately here, the carbonate ring provides an escape and a great tool to tune the miscibility of the butylene carbonate by employing the ternary solvent mixture concept. This concept allows to introduce a third solvent to the 1 ,2- butylene carbonate and water, which acts as a bridge to reduce the gap in polarity between water and butylene carbonate.After the successful preparation of the latex using 1 ,2-butylene carbonate, the diluted latex particles dispersion containing the solvent mixture (1 ,2-butylene carbonate and 1- propanol) is subjected to the dialysis step to remove the solvents and obtain a pure aqueous latex dispersion.Preliminary dialysis attempts done on diluted latex samples using only simple cellulose dialysis sleeves yielded sufficiently pure latex. The samples were analyzed using NMR in CDCI3. The concentration of 1 ,2-butylene carbonate and 1 -propanol were measured in the aqueous medium and in the solid fraction of the latex. The results thereof are shown in Table 1 . A sample of 1 ,2-butylene carbonate was taken as reference. The sample “solid fraction of the Latex before dialysis” refers to the solid sample obtained from the diluted latex obtained herein, upon the latex particles conversion from the K+form to Ba2+form, followed by isolation of the solid latex particles in Ba2+form.The sample “aqueous phase (medium)” refers to the liquid sample obtained from the diluted latex obtained herein, upon conversion of the latex particles from the K+form to Ba2+form, followed by isolation of the obtained aqueous medium. The sample “solid fraction of the Latex after 1 day of dialysis” refers to the solid sample obtained from the diluted latex obtained herein, subjected to dialysis as described above, and conversion of the purified latex particles dispersion from the K+form to Ba2+form, followed by isolation of the solid latex particles in Ba2+form. The sample “aqueous phase after 1 day (medium)” refers to the liquid sample obtained from the diluted latex obtained herein,LATER SUBMITTED SHEET100455W00134 subjected to dialysis as described above, and conversion of the purified latex particles dispersion from the K+form to Ba2+form, followed by isolation of the obtained aqueous medium.Table 1 : Results of latex purification using dialysisThe results confirm that a simple purification procedure is sufficient to get a pure latex particles aqueous dispersion. It is worth mentioning that, during the dialysis, water was changed three times, but this was not found to be critical. A further advantage of the process is that the miscible fraction of 1 ,2-butylene carbonate in water can be detected with a chemical nose until a detection limit of 10ppm, so that a simple, fast and readily available method to track the concentration of the solvents in the latex with real-time measuring tool is available.Example 2: Influence of polyesterThe particles sizes of the produced latex particles were found to not only be defined by the acid value of the applied polyester, but also the molecular weight has an influence. Experiments were carried out as in Example 1 with different polyesters, as given in Table 2. The particle sizes therein have been obtained using zetasizer technique, and also the PDI has been determined using zetasizer technique. The results in Table 2 show that there is a particle size minimum for each polyester variety. Presently it is believed that the molecular weight in combination with the acid value dictates the particle size that can be achieved. Further, the influence of the degree of neutralization is shown in Table 2.Table 2: Influence of polyester type on particle sizeLATER SUBMITTED SHEET100455W00135Since bigger particles could be obtained by decreasing the extent of neutralization, realizing smaller particles that can extend the particles size window, allowing more tunability of the latex particles. However, the particles size and the size distribution does not only depend on the percentage of the neutralized acid groups, but also on some of the other processing parameters, as seen in the table and discussed above. Using 1 ,2- butylene carbonate as solvent, very small particles sizes of 23nm could be obtained with a rather narrow size distribution, having a PDI around 0.05. It was also confirmed that bigger sizes can be obtained by decreasing the extent of neutralization of the acid groups, and this allows even further investigating smaller latex particles.Example 3: Scale-upThe experiment was carried out in the same way as in Experiment one using the polyester with Mw= 7.5 kDa, AV = 7.5, 100% neutralization using 150 g polyester, 75 g 1 ,2-butylene carbonate and 200 g 1 -propanol, the amounts of water adjusted accordingly.After dialysis, an average size d of 81 .47 nm and a PDI of 0.036 with a PDI width of 15.37 nm was obtained for the produced latex particles. The results are shown in Figure 2.Comparative example 1Latex particles were prepared similarly as in Example 3, using 250 g of the polyester and 750 g of THF, i.e. a much higher amount of solvent. Dissolution required 24 hours at 40°C, i.e. a much longer. For the neutralization and dilution and removal step, explosion-safe equipment was necessary to be used due to the low flash point of THF and its hazardous nature, making the whole process longer, more tedious and costly.

Claims

LATER SUBMITTED SHEET 100455W00136CLAIMS1 . A method of producing a latex particles dispersion, preferably an aqueous particles latex dispersion, comprising dissolving at least one polymeric compound in a solvent mixture comprising a polar organic solvent and a compound of Formula I to produce a solution of the at least one polymeric compound, adding a base to the solution of the at least one polymeric compound, adding water to the solution of the at least one polymeric compound to produce a latex particles dispersion in a ternary solvent mixture, optionally diluting the latex particles dispersion in a ternary solvent mixture to give a diluted latex particles dispersion in a ternary solvent mix, and preferably, essentially removing the polar organic solvent and the compound of Formula I from the latex particles dispersion in the ternary solvent mixture or the a diluted latex particles dispersion in a ternary solvent mixture to produce an aqueous latex particles dispersion;Formula I wherein R1and R2are independently selected from H and an alkyl residue with 1 to 6 carbon atoms.

2. The method of claim 1 , wherein adding a base involves adding an aqueous solution of the base.

3. The method of claim 1 or 2, wherein the mixture of the at least one polymeric compound and the solvent mixture is heated prior to adding the water.

4. The method of any one of claims 1 to 3, wherein the at least one polymeric compound is chosen from the group consisting of polyesters, polyurethanes,LATER SUBMITTED SHEET 100455W00137 polyepoxided, polyamided, polyethers, poly(meth)acrylates, polyolefins, polystyrene based polymers, polybutadiene-based polymers, fluorine containing polymers, polyvinyl acetate-based polymers, polyvinyl alcohol-based polymers, polyvinyl ester-based polymers, polyvinyl chloride-based polymers, polyacrylic acid based polymers, unsaturated carboxylic acid-based polymers and copolymers thereof.

5. The method of any one of claims 1 to 4, wherein the at least one polymeric compound is a polyester.

6. The method of any one of claims 1 to 5, wherein the polar organic solvent is an aliphatic alcohol.

7. The method of any one of claims 1 to 6, wherein the method comprises the step of essentially removing the polar organic solvent and the compound of Formula I from the latex particles dispersion in the ternary solvent mixture to produce an aqueous latex particles dispersion.

8. A latex particles dispersion, produced by the method of any one of claims 1 to 7.

9. Use of the latex particles dispersion of claim 8 in a printing ink.

10. A printing ink, comprising the latex particles dispersion of claim 8.

11. A printing method, comprising: applying a primer liquid on at least one surface of a recording medium; and printing an image with at least one printing ink comprising at least one latex particles dispersion on the surface of the recording medium on which the primer has been applied; wherein the at least one latex particles dispersion comprises the latex particles dispersion of claim 8.

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