NL2024530B1 - Chemical capping of ink in a nozzle to increase open time - Google Patents

Abstract

The present invention relates to an ink comprising a polymer having an acid value of > 40 mg KOH /g and water with superior capping characteristics during printing, a method 5 wherein the ink is printed in a step 2 on a recording medium provided in a step 1, and the use of the ink in a printing method. (Fig. 1)

Description

P4188NLO1 1 Chemical capping of ink in a nozzle to increase open time

FIELD OF THE INVENTION The present invention relates to an ink comprising a polymer having an acid value of > 40 mg KOH /g and water with superior capping characteristics during printing, a method wherein the ink is printed on a recording medium, and the use of the ink in a printing method.

BACKGROUND ART For printing using nozzles, e.g. inkjet printing, print heads are used in combination with inks. When using e.g. latex-based inks containing solid particles a problem can be the open time in the print head, which may result in drying of the inks. In order to avoid such drying usually certain humectants can be used in the ink to slow down the evaporation of water, which is usually the biggest part of the ink. The humectants are components that are hygroscopic, and therefore these components slow down the evaporation since they want to remain wet and extract moisture from the air. This should help with the open time inside the nozzles of a print head.

US5766327A discloses an ink composition having superior decap and dry-time performance. However, there are no solids described with regard to the ink, such as latex and/or pigments, and the ink is only based upon water-soluble parts, such as dye. These solids destabilize the ink and demix from the other parts of the formulation due to water evaporation, resulting in clogging of nozzles in a print head.

For inks comprising solids the prevention of clogging in drying is more difficult though. There thus remains a need for a simple solution for ameliorating or preventing clogging in nozzles used in printing inks, e.g. in inkjet print heads.

P4188NLO1 2

SUMMARY OF THE INVENTION The inventor found a simple ink composition to achieve the goal of preventing the destabilization of particles in inks by chemical capping. The process of chemical capping takes place due to interaction between a specific co-solvent and a specific silicone component. In a first aspect the present invention is directed to an ink, comprising - polymer particles, the polymer particularly having an acid value of > 40 mg KOH /g; - water; - at least one solvent selected from C2-C6 alkyl polyols; and - a silicon polymer with a M, of 350 g/mol or more. A further aspect of the present invention relates to a method of printing on a recording medium, comprising: - providing a recording medium; and - printing on the recording medium using the present ink. Also disclosed is the use of the present ink according in a printing method, wherein the ink is particularly applied through a nozzle. Further aspects and embodiments of the invention are dis-closed in the dependent claims and can be taken from the following description, figures and examples, without being limited thereto.

FIGURES The enclosed drawings should illustrate embodiments of the present invention and convey a further understanding thereof. In connection with the description they serve as explanation of concepts and principles of the invention. Other embodiments and many of the stated advantages can be derived in relation to the drawings. The elements of the

P4188NLO1 3 drawings are not necessarily to scale towards each other. Identical, functionally equivalent and acting equal features and components are denoted in the figures of the drawings with the same reference numbers, unless noted otherwise. Fig. 1 shows schematically a method of the present invention.

Figs. 2 and 3 show pictures of capping behavior in nozzles in the present Examples.

DETAILED DESCRIPTION

DEFINITIONS Unless defined otherwise, technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Detailed embodiments of the present invention are disclosed herein; 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 is 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).

P4188NL01 4 The M, is the number average molecular mass of the respective compound. It can be measured e.g. by gel permeation chromatography (GPC) for an accurate determination. The acid value is the mass of potassium hydroxide (KOH) in milligrams that is required to neutralize one gram of chemical substance, and can indicate the number of carboxylic acid groups in a chemical compound. It can be measured using titration with a solution of potassium hydroxide (KOH) of known concentration and a suitable indicator. Amounts within the present invention are given in wt.%, unless not stated otherwise or clear from context. In the present ink, amounts add up to 100 wt.%. In a first aspect the present invention relates to an ink, comprising - polymer particles, the polymer particularly having an acid value of > 40 mg KOH /9g, the polymer preferably being an alkali soluble polymer; - water; - at least one solvent selected from C2-C6 alkyl polyols; and - a silicon polymer with a M, of 350 g/mol or more. In the ink the polymer particles are not particularly restricted. They are contained as binder material for the final coating forming on the recording medium upon printing. The particles are prevented from agglomerating in the present ink, though, due to the interaction of the at least one solvent selected from C2-C6 alkyl polyols and the silicon polymer with a M, of 350 g/mol or more.

According to certain embodiments, the ink comprises dispersed polymer particles, e.g. latex particles. Examples of suitable inks are therefore e.g. latex inks. According to certain embodiments, the dispersed polymer particles are a water- dispersed resin (latex resin) in view of the pigment fixability to recording media. As the

P4188NLO1 water-dispersed resin, a water-dispersed resin excellent in film formability (image formability) and having high water repellency, high waterfastness, and high weatherability is useful in recording images having high waterfastness and high image density (high color developing ability). Examples of the water-dispersed resin include 5 synthetic resins and natural polymer compounds. Examples of the synthetic resins include polyester resins, e.g. sulfopolyester resins, polyurethane resins, polyepoxy resins, polyamide resins, polyether resins, poly(meth)acrylic resins, e.g. anionic (meth)acrylic resins, acryl silicone 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. Examples of the natural polymer compounds include celluloses, rosins, and natural rubbers.

In certain embodiments, the water dispersed resin used in the present invention may be made of a resin having a water soluble functional group such as a carboxylic group or a sulfonic group. In certain embodiments, the ink/ ink composition comprises a resin having a carboxylic group which has a small dissociation rate from the viewpoint of producing high speed aggregation effect of the water-dispersed resin. Since a carboxylic acid group tends to be influenced by a pH change, a dispersion state changes easily and its aggregation property is high. Examples of resins suitable for use in ink compositions according to the present embodiment are: an acrylic resin, a vinyl acetate resin, a styrene butadiene resin, a vinyl chloride resin, an acrylic styrene resin, a butadiene resin and styrene resin.

Examples of commercially available water-dispersed resin emulsions include: Joncryl 537 and 7640 (styrene-acrylic resin emulsion, made by Johnson Polymer Co, Ltd.), Microgel E-1002 and E-5002 (styrene-acrylic resin emulsion, made by Nippon Paint Co. Ltd), Voncoat 4001 (acrylic resin emulsion, made by Dainippon Ink and Chemicals Co, Ltd.), Voncoat 5454 (styrene-acrylic resin emulsion, made by Dainippon Ink and Chemicals Co,

P4188NLO1 6 Ltd.), SAE-1014 (styrene-acrylic resin emulsion, made by Zeon Japan Co, Ltd.), Jurymer ET-410 (acrylic resin emulsion, made by Nihon Junyaku Co. Ltd.), Aron HD-5 and A-104 (acrylic resin emulsion, made by Toa Gosei Co. Ltd), Saibinol SK-200 (acrylic resin emulsion, made by Saiden Chemical Industry Co, Ltd}, and Zaikthene L (acrylic resin emulsion, made by Sumitomo Seika Chemicals Co, Ltd.), acrylic copolymer emulsions of DSM Neoresins, e.g. the NeoCryl product line, in particular acrylic styrene copolymer emulsions NeoCryl A-662, NeoCryl A-633 NeoCryl A-1131, NeoCryl A-2091, NeoCryl A- 550, NeoCryl BT-101, NeoCryl SR-270, NeoCryl XK-52, NeoCryl XK-36, NeoCryl XK-39, NeoCryl XK-205, NeoCryl A-1044, NeoCryl A-1049, NeoCryl A-1110, NeoCryl A-1120, NeoCryl A-1127, NeoCryl A-2092, NeoCryl A-2099, NeoCryl A-308, NeoCryl A-45, NeoCryl A-615, NeoCryl BT-24, NeoCryl BT-26, NeoCryl BT-36, NeoCryl XK-15, NeoCryl X-151, NeoCryl XK-232, NeoCryl XK-234, NeoCryl XK-237, NeoCryl XK-238-NeoCryl XK- 86, NeoCryl XK-90 and NeoCryl XK-95 However, the water-dispersed resin emulsion is not limited to these examples.

As the fluorine-based resin, fluorine-based resin fine particles having a fluoroolefin unit are preferred. Of these, fluorine-containing resin fine particles containing a fluoroolefin unit and a vinylether unit are particularly preferable. The fluoroolefin unit is not particularly limited and may be suitably selected in accordance with the intended use. Examples thereof include -CF2CF2-, -CF2CF(CF3)-, and -CF2CFCl-. The vinylether unit is not particularly limited and may be suitably selected in accordance with the intended use. Examples thereof include -C{Ra)HC(ORb)-; wherein Ra is a hydrogen atom or a methyl group; and wherein Rb may be selected from the group consisting of -CH2Rc, - C2H4Rc, -C3H6Rc, -C4H8Rc and -C5H10Rc, wherein Rc is selected from the group consisting of a hydrogen atom (-H), an hydroxy group (-OH) or a carboxylic acid group (-COOH). As the fluorine-containing vinylether-based resin fine particles containing a fluoroolefin unit and a vinylether unit, an alternated copolymer, in which the fluoroolefin unit and the vinylether unit are alternately copolymerized, is preferable. As such a fluorine-based

P4188NLO1 7 resin fine particles, a suitably synthesized compound may be used and a commercially available product may be used.

Examples of the commercially available products include FLUONATE FEM-500 and FEM-600, DICGUARD F-52S, F-90, F-90M, F-90N and AQUAFURFURAN TE-5A produced by Dainippon Ink Chemical Industries Co Ltd; LUMIFLON FE4300, FE4500, FE4400, ASAHI GUARD AG-7105, AG-950, AG-7600, 25 AG- 7000, and AG- 1100 produced by Asahi Glass Co, Ltd.

The water-dispersed resin may be used in the form of a homopolymer, a copolymer or a composite resin, and all of water-dispersed resins having a monophase structure or core-shell structure and those prepared by power-feed emulsion polymerization may be used.

As the water-dispersed resin, it is possible to use a resin which in itself has a hydrophilic group and hence has a certain degree of self-dispersibility, and a resin which in itself has no dispersibility but to which the dispersibility is imparted with use of a surfactant and/or another resin having a hydrophilic group.

Among these resins, an emulsion of a resin obtained by emulsion polymerization or suspension polymerization of an ionomer of a polyester resin or a polyurethane resin is suitably used.

In the case of emulsion polymerization of an unsaturated monomer, a resin dispersion is obtained by initiating a polymerization reaction in the dispersed monomer phase in the monomer in water emulsion.

A polymerization initiator, a surfactant, a chain transfer agent, a chelating agent and a pH adjustor may be added to the monomer in water emulsion.

According to certain embodiments, the polymer of the polymer particles comprises at least one selected from the group consisting of anionic acrylic copolymers, which e.g. can be alkaline soluble and swellable, acrylic styrene copolymers, sulfopolyesters, and polyurethanes.

According to certain embodiments, the polymer particles are alkali soluble, i.e. the polymer therein is an alkali soluble polymer, i.e. can be dissolved in an aqueous alkaline solution.

The content of the polymer particles added in the ink of the present invention is not particularly restricted, and is preferably from 1 - 40 weight% based on the total weight

P4188NLO1 8 of the ink, and it is more preferably from 1.5 - 30 wt.%, and it is still more preferably from 2 - 25 wt.%. Even more preferably, the amount of the polymer particles contained in the ink, as a solid content, is 2.5 wt.% to 18 wt.%, and more preferably 3 wt.% to 15 wt.%, relative to the total ink composition.

The ink comprises water as a solvent, e.g. in the form of demi water. The water is used as a carrier. The content of the water is not particularly restricted and can be adjusted based on the further components, e.g. between 20 and 80 wt.%, e.g. between 45 and 75 wt.%, e.g. between 50 and 70 wt.%.

The at least one solvent selected from C2-C6 alkyl polyols is not particularly restricted. In the C2-C6 alkyl polyol, no further functional groups like aldehyde, carboxyl, nitro, amino, etc. groups are contained according to certain embodiments, i.e. derivatives of C2-C6 alkyl polyols are not encompassed.

According to certain embodiments, the at least one solvent selected from C2-C6 alkyl polyols is selected from diols like ethylene glycol, propanediol, e.g. 1,2-propanediol, 1,3- propanediol, butanediol, e.g. 1,2-butanediol, 1,3-butanediol, 2-methyl-1,3-popanediol, pentanediol, e.g. 1,5-pentanediol, 1,3-pentanediol, 1,5-pentanediol, 1,2-pentanedio, 2,3- pentanediol, 2,4-pentanediol, methylbutanediols, hexanediol, e.g. 1,6-hexanediol, 1,5- hexanediol, 14-hexanediol, 1,3-hexanediol, 1,2-hexanediol, 2,5-hexanediol, 2,4- hexanediol, 2,3-hexanediol, 3,4-hexanediol, methylpropanediols; and/or further polyols, e.g. triols like glycerol, butanetriols, pentanetriols, hexanetriols, etc. According to certain embodiments, the at least one solvent selected from C2-C6 alkyl polyols is selected from 2-methyl-1,3-popanediol, 1,5-pentanediol, and/or glycerol. According to certain embodiments, the at least one solvent selected from C2-C6 alkyl polyols is a diol. According to certain embodiments, the at least one solvent selected from C2-C6 alkyl polyols is 2-methyl-1,3-popanediol (MPD). The usage of MPD as co-solvent particularly also allows adhesion to plastic substrates like vinyl as or as part of a recording medium.

P4188NLO1 9 According to certain embodiments, the at least one solvent selected from C2-C6 alkyl polyols is contained in an amount of 3 to 50 wt.%, preferably 7 to 41 wt.%, further preferably 11 to 33 wt.%, even further preferably 13 to 21 wt.%, based on the total amount of the ink.

The ink formulation can further contain other co-solvents apart from the at least one solvent selected from C2-C6 alkyl polyols which are usually used in inks and not particularly restricted. According to certain embodiments, no further co-solvent is contained in the ink besides the at least one solvent selected from C2-C6 alkyl polyols.

Further, the silicon polymer with a M, of 350 g/mol or more is not particularly restricted. It can be in the form of an emulsion or of a dissolved polymer.

According to certain embodiments, the silicon polymer has a M, of 2000 g/mol or more, preferably 3000 g/mol or more, further preferably 3500 g/mol or more. Silicone emulsion with higher M, silicone polymer also functions as a slip additive in the coating formed by the ink on the recording medium and are thus preferred.

The amount of silicon polymer in the ink is not particularly restricted and can be eg.

contained in an amount of 0.1 wt.% or more and 10 wt.% or less, e.g. 0.15 wt.% or more and 7 wt.% or less, e.g. 0.25 wt.% or more and 4.5 wt.% or less, e.g. 0.4 wt. or more and 3 wt.% or less, e.g. 0.45 wt.% or more and 2.5 wt.% or less, e.g. 0.5 wt.% or more and 2 wt.% or less.

In the present ink, solids, particularly the polymer particles, but e.g. also pigments, within the ink that are usually destabilized due to separation of particles on the bottom due to density differences can be avoided to agglomerate in a nozzle and clog it due to the combination of the specific co-solvent and the higher M, silicone component, which provide a chemical capping. The silicone component together with the co-solvent

P4188NLO1 10 demixes on the bottom of the nozzle, thereby creating a transparent layer which slows down the destabilization of solid particles. The ink comprises at least one colorant, which may be a pigment, i.e. a solid coloring agent, or a dye, i.e. a liquid and/or dissolvable colorant.

According to certain embodiments, the ink comprises at least one pigment, particularly in the form of particles. The color of the pigment, as well as of dyes or the colorant in general, can be any color used in printing, e.g. cyan (C), magenta (M), yellow (Y), black (K), metallic, white, fluorescent, etc. If the pigment is contained in the form of particles, the particle shape is not particularly restricted.

The 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 dispersed and/or dissolved. Examples of the pigment and/or dye usable in the present invention include those commonly known without any limitation, and either a water-dispersed pigment or an oil-dispersed pigment and/or a water-soluble dye 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.

P4188NLO1 11 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), polycyclic 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: Cl.

Pigment Red 1, C.L Pigment Red 2, CL Pigment Red 3, CL Pigment Red 5, CI Pigment Red 6, CI Pigment Red 7, CL Pigment Red 15, CL Pigment Red 16, Cl.

Pigment Red 17, CI Pigment Red 22, CL Pigment Red 23, CI Pigment Red 31, CI Pigment Red 38, CI Pigment Red 48:1, CL Pigment Red 48:2 (Permanent Red 2B(Ca)), C1. Pigment Red 48:3, CI.

Pigment Red 48:4, CL.

Pigment Red 49:1, CI Pigment Red 52:2; CI Pigment Red 53:1, CI.

Pigment Red 57:1 (Brilliant Carmine 6B), C.I.

Pigment Red 60:1, C1 Pigment Red 63:1, C.I.

Pigment Red 64:1, CL Pigment Red 81. CI Pigment Red 83, CI Pigment Red 88, CI Pigment Red 101(colcothar), CI Pigment Red 104, CI Pigment Red 106, CI Pigment Red 108 (Cadmium Red), CI Pigment Red 112, CL Pigment Red 114, CI Pigment Red 122 (Quinacridone Magenta), C1. Pigment Red 123, CL Pigment Red 139, CI.

Pigment Red 44, CI.

Pigment Red 146, CL Pigment Red 149, C.. Pigment Red 166, CI.

Pigment Red 168, CI.

Pigment Red 170, CL Pigment Red 172, CI.

Pigment Red 177, CI Pigment Red 178, CJ.

Pigment Red 179, CI Pigment Red 185, CI.

Pigment Red 190, C.I.

Pigment Red 193, CL Pigment Red 209, CL Pigment Red 219 and CI Pigment Red 222, CI.

Pigment Violet 1 (Rhodamine Lake), CL.

Pigment Violet 3, C1. Pigment Violet 5:1, CL.

Pigment Violet 16, C.I.

Pigment Violet 19, C1 Pigment Violet 23 and Cl Pigment Violet 38.

P4188NLO1 12 Examples of pigments for orange or yellow include: CI. Pigment Yellow 1, CI. Pigment Yellow 3, CL Pigment Yellow 12, CI Pigment Yellow 13, C1 Pigment Yellow 14, CL Pigment Yellow 15, CI Pigment Yellow 15:3, CI Pigment Yellow 17, CI. Pigment Yellow 24, CL Pigment Yellow 34, CL Pigment Yellow 35, CI Pigment Yellow 37, C1 Pigment Yellow 42 (yellow iron oxides), CI Pigment Yellow 53, CJ. Pigment Yellow 55, CL Pigment Yellow 74, CI. Pigment Yellow 81, CI. Pigment Yellow 83, C1. Pigment Yellow 93, CL. Pigment Yellow 94, CL Pigment Yellow 95, CI Pigment Yellow 97, CI Pigment Yellow 98, C1. Pigment Yellow 100, CL Pigment Yellow 101, CI Pigment Yellow 104, C.L Pigment Yellow 408, CI Pigment Yellow 109, CI Pigment Yellow 110, CI Pigment Yellow 117, CL Pigment Yellow 120, C1 Pigment Yellow 128, CI. Pigment Yellow 138, C.L Pigment Yellow 150, CI Pigment Yellow 151, CJ. Pigment Yellow 153 and CI Pigment Yellow 183; CL Pigment Orange 5, CI Pigment Orange 13, CI. Pigment Orange 16, CL Pigment Orange 17, CL Pigment Orange 31, CI Pigment Orange 34, CL Pigment Orange 36, C1 Pigment Orange 43, and CI. Pigment Orange 51.

Examples of pigments for green or cyan include: C1 Pigment Blue 1, C1. Pigment Blue 2, CL. Pigment Blue 15, CI. Pigment Blue 15:1, CI. Pigment Blue 15:2, C1 Pigment Blue 15:3 (Phthalocyanine Blue), CI. Pigment Blue 16, CI Pigment Blue 17:1, CL. Pigment Blue 56, CI Pigment Blue 60, CI. Pigment Blue 63, Cl. Pigment Green 1, CI Pigment Green 4, CL. Pigment Green 7, CI. Pigment Green 8, CI. Pigment Green 10, 25 CI. Pigment Green 17, C.. Pigment Green 18 and C.I. 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: CI. Pigment Red 209, 224, 177, and 194, CI Pigment Orange 43, Cl Vat Violet 3, Cl Pigment Violet 19, 23, and 37, CI Pigment Green 36, and 7, C.L Pigment Blue 15:6. Further, examples of pigments for black include: CI. Pigment Black 1, CI. Pigment Black 6, CI Pigment Black 7 and CI Pigment Black 11. Specific examples of pigments for black

P4188NL01 13 color ink usable in the present invention include carbon blacks (e.g., furnace black, lamp black, acetylene black, and channel black); (CL Pigment Black 7) or metal based pigments (e.g., copper, iron (CI Pigment Black 11), and titanium oxide; and organic pigments (e.g. aniline black (C.I. Pigment Black 1).

The amount of the water-insoluble pigment contained in the inkjet ink, as a solid content, is preferably 0.5 weight% to 15 weight%, more preferably 0.8 weight% to 10 weight%, and even more preferably between 1 weight% and 6 weight%. When the amount of the water-insoluble pigment is less than 0.5 weight%, the color developing ability and image density of the ink may degrade. When it is more than 15 weight%, unfavorably, the viscosity of the ink is increased, causing a degradation in ink ejection stability. According to certain embodiments, the ink further comprises at least one surfactant. The surfactant therein is not particularly restricted and is added for spreading of the ink during printing and in nozzles. Any surfactant that is usually used in inks can be applied, e.g. non-ionic surfactants, e.g. ethyoxylated surfactants, amineoxide based surfactants, anionic surfactants, zwitterionic surfactant, amphotheric surfactants, sugar surfactants, alkanediols, etc.

It was noted that the surfactant chemistry did not have any influence on the chemical capping. This is rather remarkable since the effects are thought to be a surface active effect. This means that the silicone component is stronger surface active causing chemical capping.

The amount of surfactant is not particularly restricted. It can be e.g. contained in an amount of 0 to 10 wt.%, e.g. 0.1 to 7.5 wt.%, e.g. 0.2 to 6 wt.%, e.g. 0.5 to 4 wt.%, e.g. 0.7 to 3 wt.%, e.g. 0.75 to 2 wt.

P4188NLO1 14 According to certain embodiments, the ink comprises a wax emulsion, which is not particularly restricted, e.g. in amounts of less than 10 wt.%, e.g. less than 5 wt.%, e.g. less than 3 wt.%. As it may not be contained a lower limit is 0 wt.%, and the lower limit of the way emulsion may be e.g. 0.2 wt.%, 0.5 wt.%, or 1 wt.%.

Further, also additives usually applied in inks can be contained in the ink. According to certain embodiments, the ink has a pH of 7 or less.

According to certain embodiments, the ink essentially consists of (i.e. contains not more than 5 wt.% additives, e.g. less than 3% additives or even less than 2 wt.% or less than 1 wt.%) or consists of polymer particles, the polymer particularly having an acid value of > 40 mg KOH /g; water; at least one solvent selected from C2-C6 alkyl polyols; at least one silicon polymer with a M; of 350 g/mol or more, and optionally at least one surfactant.

Furthermore disclosed is a method of printing on a recording medium, comprising: - providing a recording medium; and - printing on the recording medium using the ink of the present invention.

The recording medium is not particularly restricted, and can be e.g. a solvent absorbing medium like a cellulose fiber containing medium, e.g. paper, cardboard, etc, a textile, or a not solvent absorbing medium like a foil, e.g. a polymeric/plastic or metallic foil, a coated medium coated with a polymer film, etc.

The providing a recording medium as well as the printing using the ink are not particularly restricted and can be suitably carried out, particularly as in inkjet printing. Also further steps like recording medium pre-treatment, fixation, etc. usually carried out in printing methods can be comprises in the present method.

P4188NLO1 15 According to certain embodiments, the ink is printed by application through a nozzle. Nozzles can be e.g. present in print heads, e.g. inkjet heads, etc. The present ink can be stabilized inside the nozzle, so that clogging can be prevented, and thus is particularly useful for printing through a nozzle.

According to certain embodiments, a pressure to apply the ink through the nozzle is at most 10 mbar, preferably at most 7 mbar. The present ink does not form a cap in the nozzle and thus can be easily applied, even after prolonged time, at reduced pressure compared to a standard ink where a cap forms due to ink drying.

Additionally disclosed is the use of the present ink in a printing method, wherein the ink is particularly applied through a nozzle. 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.

EXAMPLES The 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.

Different ink recipes were prepared with the amounts given in Table 1.

P4188NLO1 16 Table 1: recipes for test-inks to prove chemical capping with a transparent liquid layer (wt.%) sies [0 [u [oo [B ! 2-methyl-1,3-propanediol 2 glycerol + betaine 3 1,5-pentanediol In the recipes, the silicone additive was ABCR AB111808 with a M,, of 3600 g/mol.

While recipes 1, 3 and 5 are in line with the invention, recipe 4 does not contain a silicone additive and thus represents a comparative example.

Recipe 2 contains a different co-solvent and represents a comparative example as well.

The effect of the invention is shown by letting the different ink recipes dry in a 10 pl capillary for one hour.

After the hour has passed, the “dried” ink is pushed out of the capillary and the pressure is measured in mbar and a video is recorded to visualize the tip of the capillary.

The video for recipe 1 shows that with the present invention a clear liquid layer has separated on the bottom of the capillary and ensures chemical capping with a liquid, as e.g. seen in Fig. 2, which shows the capillary of recipe 1 after one hour.

In contrast, a solid cap had formed after 1 hour for recipe 2, which is seen in Fig. 3 when pressing it out as an observed destabilized lid.

Thus, if the 2-methyl-1,3-propandiol is replaced by a combination of glycerol and betaine (being humectants), then a solid cap is formed, thereby increasing the necessary pressure to remove the dried ink.

To proof

P4188NLO1 17 that the invention is not driven by density differences of the pigment, also a white recipe is measured in recipe 3. If the process would be driven solely by density of the white pigment, titanium dioxide, would be clogged at the bottom since it has the highest density of 4.2 g/cm? instead of the other components at +1 g/cm’. However, also chemical capping is observed for recipe 3, which therefore proves that the process is driven by a stronger physical process than density differences of the components. Similarly, chemical capping was observed for recipe 5, while also a solid cap was formed for recipe 4. The pressures for pressing out the ink were 5.90 mbar for recipe 1, 5.46 mbar for recipe 3, 8.72 mbar for recipe 4 and 5.20 mbar for recipe 5. To also examine the influence of the further components, further experiments were carried out with variations of the recipes.

When replacing ABCR AB111808 as silicone polymer with Silwet L77, a silicone polymer with a M,, of 339 g/mol, no chemical capping was observed. However, use of the higher M, silicone surface active component Byk LP G 22107 with a M, of more than 3500 g/mol again resulted in chemical capping when the specific co-solvent was used as well.

Replacing the acrylic copolymer resin by a styrenated acrylic resin, a polyester sulfonate resin, or a urethane resin also did not change the chemical capping behavior. Also, different surfactants like anionic sulfosuccinate (AOT), trisiloxane ethoxylate (L77), ethoxylated/propoxylated (TW510), acetylenic ethoxylate (S440), acetylenic gemini ethoxylate (D604), ethoxylated alkyl alcohol (MW-SU) show no influence on the effect of chemical capping. This is rather remarkable since the effects are thought to be a surface active effect. This means that the silicone component is stronger surface active causing chemical capping. As can be seen from the above examples also the pigments did not show an influence on the capping behavior. Also metallic pigments did not notably change the capping behavior, and still a low pressure is needed for releasing the ink.

P4188NLO1 18 Furthermore, the inclusion of a Carnauba-wax nonionically stabilized emulsion did not change the capping behavior.

For further testing the influence of the co-solvent, also further co-solvents were tested.

The use of glucose, sucrose and tetraethylene glycol resulted in a viscous cap and a balloon during ejection of the ink.

Diethylene glycol and 2-pyrrolidone as co-solvent resulted in a capping with a lid, similar to recipe 2. Diacetin as co-solvent resulted in a highly viscous ink with the formation of a partial solid cap.

This shows that the co-solvent choice is dominant in the chemical capping behavior in combination with the silicone-component.

P4188NLO1 19 Embodiments

1. An ink, comprising - polymer particles, the polymer particularly having an acid value of > 40 mg KOH J/g - water; - at least one solvent selected from C2-C6 alkyl polyols; and - a silicon polymer with a M, of 350 g/mol or more.

2. The ink according to claim 1, wherein the at least one solvent selected from C2- C6 alkyl polyols is selected from 2-methyl-1,3-popanediol, 1,5-pentanediol, and/or glycerol, preferably 2-methyl-1,3-popanediol, 1,5-pentanediol.

3. The ink according to claim 2, wherein the at least one solvent selected from C2- C6 alkyl polyols is 2-methyl-1,3-popanediol.

4. The ink according to any one of the preceding claims, wherein the at least one solvent selected from C2-C6 alkyl polyols is contained in an amount of 3 to 50 wt.%, preferably 7 to 41 wt.%, further preferably 11 to 33 wt.%, even further preferably 13 to 21 wt.%, based on the total amount of the ink.

5. The ink according to any one of the preceding claims, wherein the silicon polymer has a M, of 2000 g/mol or more, preferably 3000 g/mol or more, further preferably 3500 g/mol or more.

6. The ink according to any one of the preceding claims, wherein the polymer of the polymer particles comprises at least one selected from the group consisting of anionic acrylic copolymers, acrylic styrene copolymers, sulfopolyesters, and polyurethanes.

P4188NLO1 20

7. The ink according to any one of the preceding claims, further comprising at least one pigment, particularly in the form of particles.

8. The ink according to any one of the preceding claims, further comprising at least one surfactant.

9. A method of printing on a recording medium, comprising: - providing a recording medium; and - printing on the recording medium using the ink of any one of claims 1 to 8.

10. The method of claim 9, wherein the ink is printed by application through a nozzle.

11. The method of claim 10, wherein a pressure to apply the ink through the nozzle is at most 10 mbar, preferably at most 7 mbar.

12. Use of the ink according to any one of claims 1 to 8 in a printing method, wherein the ink is particularly applied through a nozzle.

Claims (12)

P4188NL01 21 ConclusiesP4188EN01 21 Conclusions 1. Een inkt, omvattende se polymeerdeeltjes, waarbij het polymeer in het bijzonder een zuurwaarde van» 40 mg KOH / g heeft; es water e ten minste één oplosmiddel gekozen uit C2-C6-alkylpolyolen; en e een siliciumpoelymeer met een Mn van 350 g / mol of meer.An ink comprising polymer particles, wherein the polymer has in particular an acid value of 40 mg KOH/g; es water e at least one solvent selected from C 2 -C 6 alkyl polyols; and e a silicon polymer having an Mn of 350 g/mol or more. 2. De inkt volgens conclusie 1, waarbij het ten minste ene oplosmiddel gekozen uit C2- C6-alkylpolyolen is gekozen uit 2-methyl-1,3-popaandiol, 1,5-pentaandiol en / of giycerol, bij voorkeur 2-methyi-1, 3-popaandicl, 1,5-pentaandiolThe ink of claim 1, wherein the at least one solvent selected from C 2 -C 6 alkyl polyols is selected from 2-methyl-1,3-popanediol, 1,5-pentanediol and/or glycerol, preferably 2-methyl- 1,3-popanedicl, 1,5-pentanediol 3. De inkt volgens conclusie 2, waarbij het ten minste ene oplosmiddel gekozen uit C2- C6-alkylpolyolen 2-methyl-1,3-popaandiol is,The ink of claim 2, wherein the at least one solvent selected from C 2 -C 6 alkyl polyols is 2-methyl-1,3-popanediol, 4. De inkt volgens één van de voorgaande conclusies, waarbij het ten minste ene oplosmiddel gekozen uit C2-C6-alkylpolyolen aanwezig is In een hoeveelheid van 3 tot 50 gew.%, bij voorkeur 7 tot 41 gew.%, met nog meer voorkeur 11 tot 33 gew.%, met nog meer voorkeur 13 tot 21 gew.%, gebaseerd op de totale hoeveelheid inkt,The ink according to any one of the preceding claims, wherein the at least one solvent selected from C 2 -C 6 alkyl polyols is present in an amount of 3 to 50% by weight, preferably 7 to 41% by weight, even more preferably 11 to 33 wt%, even more preferably 13 to 21 wt%, based on the total amount of ink, 5. De inkt volgens één van de voorgaande conclusies, waarbij het siliciumpolymeer een Mn van 2000 g/mol of meer, bij voorkeur 3000 g/mol of meer, met nog meer voorkeur 3500 g/mol of meer heeft.The ink according to any one of the preceding claims, wherein the silicon polymer has an Mn of 2000 g/mol or more, preferably 3000 g/mol or more, even more preferably 3500 g/mol or more. 6. De inkt volgens één van de voorgaande conclusies, waarbij het polymeer van de polymeerdeesltjes ten minste éón omvat gekozen uit de groep bestaande uit anionische acrylcopolymeren, acrylstyreencopolymeren, sulfopolyesters en polyurethanen.The ink of any preceding claim, wherein the polymer of the polymer particles comprises at least one selected from the group consisting of anionic acrylic copolymers, acrylic styrene copolymers, sulfopolyesters and polyurethanes. P4188NLO1 22P4188NLO1 22 7. De inkt volgens één van de voorgaande conclusies, verder omvattende ten minste éên pigment, in het bijzonder In de vorm van deeltjes.The ink according to any one of the preceding claims, further comprising at least one pigment, especially in the form of particles. 8. De Inkt volgens één van de voorgaande conclusies, verder omvattende ten minste één opperviakteactieve stof.The ink of any preceding claim further comprising at least one surfactant. 9. Een methode voor afdrukken op een opname-medium, omvattende: - het verschaffen van een opname-mediumy en - afdrukken op het opname-medium met behulp van de inkt volgens één van de conclusies 1 tot en met &A method of printing on a recording medium, comprising: - providing a recording medium and - printing on the recording medium using the ink according to any one of claims 1 to & 10. Werkwijze volgens conclusie 3, waarbij de inkt wordt gedrukt door aanbrengen via een nozzle.The method of claim 3, wherein the ink is printed by nozzle application. 11. Werkwijze volgens conclusie 10, waarbij een druk om de Inkt door de nozzle aan te brengen ten hoogste 10 mbar is, bij voorkeur ten hoogste 7 mbar.A method according to claim 10, wherein a pressure to apply the Ink through the nozzle is at most 10 mbar, preferably at most 7 mbar. 12. Gebruik van de inkt volgens een van de conciusies 1 tot 8 in een drukmethode, waarbij de inkt in het bijzonder wordt aangebracht door een nozzle.Use of the ink according to any one of claims 1 to 8 in a printing method, wherein the ink is particularly applied through a nozzle.