WO2005047398A1

WO2005047398A1 - Cleaning metallised die aqueous solutions

Info

Publication number: WO2005047398A1
Application number: PCT/EP2004/012884
Authority: WO
Inventors: Till Borchert; Klaus Saitmacher; Josef Geisenberger
Original assignee: Clariant Gmbh
Priority date: 2003-11-17
Filing date: 2004-11-13
Publication date: 2005-05-26

Abstract

The invention relates to a method for removing free ions of heavy or polyvalent metals which are contained in which is characterised in that the die aqueous solution first is brought into contact with a sulphide precipitating agent, a precipitated heavy-metal sulphide is removed by filtering and, afterwards the thus treated die solution is brought into contact with a chelating ion-exchanging resin which contains iminodiacetate and/or thiol groups.

Description

description

Cleaning of aqueous solutions of metallized dyes

The present invention describes a process for the purification of water-soluble dyes which are used as color-imparting components in recording liquids and inks, in particular in inks for the ink-jet printing process.

The inkjet process is a non-contact printing process, whereby a distinction is generally made between two printing techniques: drop-on-demand and continuous stream. The drop-on-demand principle is based on the fact that the ink in the form of a drop from a nozzle - electronically controlled - is placed in the right place at the right time, whereas with continuous stream printing the ink is permanently released and then, also after electronic charging either hits the recording medium (e.g. paper), or is distracted into a receptacle.

Impurities in the dye solutions used to manufacture the inks can impair the stability of the inks, which can lead to agglomeration or even precipitation of the dye. In order to avoid blockages in the nozzles and deposits (cogation) in print heads of recording machines or printers due to contamination or foreign substances, the recording liquids or inks must meet the corresponding requirements, in particular with regard to their purity. The most important role is played by the dyes used in the inks. In particular, contamination of divalent or multivalent metal cations in the dye solutions can lead to difficulties in printing or to stability problems in the inks. In order to prevent such difficulties, it is necessary to adjust the concentrations of divalent or multivalent metal cations in the dye solutions so that they are below a critical limit concentration specified by the printer manufacturers. This is currently a maximum of 10 ppm. The heavy metals that are used to metallize the dyes are of particular importance. These are usually used in excess in the manufacturing process.

From DE-A-42 13 163 a method for removing metal ions from dye solutions is known which is to reduce the heavy metal ion content to below 10 ppm with the aid of zeolites. However, an initial concentration of metal ions of 100 to a maximum of 1000 ppm is assumed. JP 61-076553A also describes a method with which Mg, Ca, Fe, Al, Ni and Zn ions can be removed from dye solutions with the aid of a chelating resin. However, this method does not solve the present problem since it assumes a metal cation content of at most about 500 ppm. Removal of copper ions is not considered there.

The removal of the excess of free heavy metals, which can amount to more than 10% (= 100,000 ppm), to below the required limit concentration in the dye concentrate by an inexpensive process has not been possible until now without destroying the heavy metal complex of the dye molecule itself.

It has now been found that a two-stage cleaning process with a sulfide-containing precipitation reagent and a subsequent cleaning with a certain ion exchange resin can surprisingly solve this problem.

The invention relates to a process for removing free heavy metal ions and polyvalent metal ions from dye solutions, characterized in that the aqueous dye solution is first brought into contact with a sulfidic precipitant, preferably an alkali metal sulfide, alkali metal bisulfide or alkali metal polysulfide, and the precipitated heavy metal sulfide is then removed treated like this Dye solution is brought into contact with a chelating ion exchange resin containing iminodiacetate and / or thiol groups.

The dye solutions contain metallized, anionic dyes from the group of direct, acid, reactive and disperse dyes with one or more metals, preferably from the group Cu, Fe, Co, Ni, Cr, Zn, Mn and Al. Cu complex dyes are preferred for the purposes of the present invention.

The dye solutions can be used as a single component or in any

Mixtures with each other or in any mixtures with non-metal-containing

Dyes or with pigments are subjected to the cleaning process according to the invention.

The reactive dyes can be reactive, vinylized or hydroxylated

Form or, after reaction with organic O, N or S nucleophiles, in an unreactive form.

Examples of such reactive dyes are: C.I. Reactive Black 8, C.I. Reactive black

31; C.I. Reactive Blue 7, C.I. Reactive Blue 14, C.I. Reactive Blue 21, C.I.

Reactive Blue 28, C.I. Reactive Blue 38, C.I. Reactive Blue 82, C.I. Reactive Blue

89, C.I. Reactive Blue 158, C.I. Reactive Blue 182, C.I. Reactive Blue 190, C.I.

Reactive Blue 203, C.I. Reactive Blue 216, C.I. Reactive Blue 220, C.I. Reactive

Blue 244; C.I. Reactive Violet 1, C.I. Reactive violet 5; C.I. Reactive Red 6, C.I.

Reactive Red 23 and C.I. Reactive Brown 18th

Examples of direct dyes are C.I. Direct Blue 76, C.I. Direct Blue 84, C.I.

Direct Blue 86, C.I. Direct Blue 87, C.I. Direct Blue 98, C.I. Direct Blue 199, C.I.

Direct Blue 202, C.I. Direct Blue 290; C.I. Direct Black 112; C.I. Direct Brown 95 and C.I. Direct Violet 47.

Examples of acid dyes are C.I. Acid Blue 87, C.I. Acid Blue 185 and C.I.

Acid Blue 249.

For the purposes of the present invention, particular preference is given to Cl Direct Blue 199 of the formula (1a), Cl Reactive Black 31 of the formula (1b), Cl Reactive Black 8, Cl Reactive Red 23 of the formula (1c).

X = H, SO.NH, SOoNa (1a)

MO, SO

(1c)

Further examples of Cu complex dyes are compounds of the formulas (1d) to (1t) below.

(1r)

In the dyes of the formulas (1b) to (1t), M is preferably hydrogen and / or sodium, depending on the pH.

The concentration of the dyes in the dye solution is preferably 1 to

30% by weight, in particular 5 to 20% by weight.

The method according to the invention usually turns the

Metallization used (heavy) metal cations Cu ²⁺ , Fe ²⁺ , Fe ³⁺ , Co ²⁺ , Co ³⁺ ,

Ni ²⁺ , Zn ²⁺ , Mn ²⁺ , Cr ³⁺ , Al ³⁺ , preferably Cu ²⁺ , removed from the dye solution.

The content of the free metal cations present in excess is in the

Usually at 50 ppm to greater than or equal to 100,000 ppm, mostly at 500 ppm to 60,000 ppm, in particular at 1000 ppm to 20,000 ppm.

As a side effect, further metal cations, in particular Ca ²⁺ and Mg ^{2+, are} removed.

The dye solutions can be used as saline process solutions or as

Examples include solutions desalted by reverse osmosis. Typical salts in Process solutions are alkali metal chlorides and sulfates.

In the first step of the cleaning process, the dye solution is treated with a precipitant, preferably sodium sulfide, sodium hydrogen sulfide or sodium polysulfide. For this purpose, the sulfidic precipitant dissolved in water is expediently metered into the dye solution and then stirred, preferably for 10 minutes to 8 hours, at a pH of 3 to 10, a pressure of 1 to 6 bar, at a temperature of 0 to 60 ° C. , in particular 10 to 30 ° C, and in an amount which corresponds approximately to the equivalent amount of the metal cations to be precipitated. Overdosing of the precipitant should be avoided, since there is always a risk of the metal being demetallized. For this reason it is also advisable to determine the approximate amount of precipitant required by performing a redox titration beforehand. In a preferred embodiment, the precipitant is metered in under potentiometric control. As soon as the potentiometer indicates a potential jump, the addition of the precipitant is stopped. For better separation of the metal sulfide, a commercially available filter aid can be added to the dye solution. This cleaning step can usually reduce the amount of heavy metal cations to 50 to 500 ppm. If the second cleaning step does not take place immediately after the first, the precipitated metal sulfide is filtered out of the dye solution by deep filtration.

The second step of the method according to the invention can take place directly after the first, or can take place independently of it both in terms of time and space. In this second step, the dye solution is post-treated with an ion exchange resin to further remove any metal cations still present. Possible ion exchangers are polymeric cation exchangers, preferably of the styrene type, with the functional groups iminodiacetate and / or thiol and the counter cations proton and sodium. Suitable ion exchange resins are commercially available, for example under the name © Amberlite IRC 748 and Amberlite GT 73 from Rohm & Haas. The ion exchange resins are expediently washed with water before use and then, if appropriate, converted to their Na form or to their H form by means of sodium hydroxide solution or sodium chloride solution. This can be done in batch or by pouring the resin into a column or other suitable container.

The treatment of the dye solution with the ion exchange resin can be carried out in a batch by stirring for 10 minutes to 24 hours, at a pH of 3 to 10, at a pressure of 1 to 6 bar and at a temperature of 0 to 80 ° C., preferably 10 to 30 ° C, and finally all insoluble constituents are separated off by filtration. In practice, the amounts of ion exchange resin used are usually between 0.01% and 20% of the mass of the dye solution, preferably between 0.1% and 5%. The dye solution can also at a pH of 3 to 10, at a pressure of 1 to 6 bar and at a temperature of 0 to 80 ° C, preferably 10 to 30 ° C, in the upstream or downstream through one or more columns or others suitable containers, which are filled with the ion exchange resin. Depending on the volume to be processed and the concentration of heavy metal ions, there are, for example, column diameters of 5 cm to 30 cm and column lengths of 50 cm to 3 m. The volume flows through the column range, for example, between 1 l / min and 20 l / min.

The post-treatment can reduce the metal cation content to below 10 ppm.

The dye solution purified in the manner described can be treated with activated carbon for further cleaning. It is then roughly pre-filtered to remove all insoluble constituents and then deep-filtered.

A crude dye solution which has been treated according to the invention but has not yet been desalinated is expediently desalinated by reverse osmosis before further use. A solution that has already been desalinated should be desalted again briefly. The dye solutions cleaned according to the invention do not lead to blockage of the printing nozzles and deposits on the print heads in the ink jet printing process and can therefore be used directly as ink jet inks or can be further processed with or without intermediate insulation. In principle, ink-jet inks are those based on water and water, microemulsion inks and inks that work according to the hot-melt process. Ink-jet inks generally contain a total of 0.5 to 15% by weight, preferably 1.5 to 8% by weight (calculated on a dry basis) of one or more dyes cleaned according to the invention. Microemulsion inks are based on organic solvents, water and possibly an additional hydrotropic substance (interface mediator). Microemulsion inks generally contain 0.5 to 15% by weight, preferably 1.5 to 8% by weight, of one or more dyes cleaned according to the invention, 5 to 99% by weight of water and 0.5 to 94.5% by weight. -% organic solvent and / or hydrotropic compound.

"Solvent based" ink-jet inks preferably contain 0.5 to 15% by weight of one or more dyes cleaned according to the invention, 85 to 99.5% by weight of organic solvent and / or hydrotropic compounds. Hot-melt inks are mostly based on waxes, fatty acids, fatty alcohols or sulfonamides, which are solid at room temperature and become liquid when heated, the preferred melting range being between approx. 60 ° C and approx. 140 ° C. Hot-melt ink-jet inks essentially consist, for example, of 20 to 90% by weight of wax and 1 to 10% by weight of one or more dyes cleaned according to the invention. Furthermore, 0 to 20% by weight of an additional polymer (as a "dye dissolver"), 0 to 5% by weight of dispersing aid, 0 to 20% by weight of viscosity modifier, 0 to 20% by weight of plasticizer, 0 to 10% by weight % Stickiness additive, 0 to 10% by weight transparency stabilizer (prevents, for example, crystallization of the waxes) and 0 to 2% by weight antioxidant. Furthermore, the dyes cleaned according to the invention are also used as colorants for color filters, both for additive and for subtractive color generation, and as colorants for electronic inks (“electronic inks” or “e-inks”) or "Electronic paper"("e-paper") suitable.

The dyes cleaned according to the invention can of course also be used in general for dyeing high molecular weight organic materials of natural or synthetic origin, for example plastics, resins, lacquers, paints, electrophotographic toners and developers, electret materials, color filters and inks, printing inks and seeds. High molecular weight organic materials which can be colored with the dyes cleaned according to the invention are, for example, cellulose compounds, such as, for example, cellulose ethers and esters, such as ethyl cellulose, nitrocellulose, cellulose acetates or cellulose butyrates, natural binders, such as, for example, fatty acids, fatty oils, resins and their conversion products, or Synthetic resins, such as polycondensates, polyadducts, polymers and copolymers, such as, for example, aminoplasts, in particular urea and melamine-formaldehyde resins, alkyd resins, acrylic resins, phenoplasts and phenolic resins, such as novolaks or resols, urea resins, polyvinylyls, such as polyvinyl alcohols, polyvinyl acetals or poly, vinyl acetate polyols, polyvinyl ether polyols, polyvinyl ether polyols , such as polystyrene, polyvinyl chloride, polyethylene or polypropylene, poly (meth) acrylates and their copolymers, such as polyacrylic acid esters or polyacrylonitriles, polyamides, polyesters, polyurethanes, coumarone indene and hydrocarbon ff resins, epoxy resins, unsaturated synthetic resins (polyester, acrylates) with the different hardening mechanisms, waxes, aldehyde and ketone resins, rubber, rubber and its derivatives and latices, casein, silicones and silicone resins; individually or in mixtures. It does not matter whether the high-molecular organic compounds mentioned are in the form of plastic masses, melts or in the form of spinning solutions, dispersions, lacquers, paints or printing inks. Based on the high-molecular organic material to be colored, the dyes cleaned according to the invention are used in an amount of 0.05 to 30% by weight, preferably 0.1 to 15% by weight.

The dyes cleaned according to the invention are also suitable as colorants in electrophotographic toners and developers, such as mono- or Two-component powder toners (also called one- or two-component developers), magnetic toners, liquid toners, latex toners, polymerization toners and special toners. Typical toner binders are polymerization, polyaddition and polycondensation resins, such as styrene, styrene-acrylate, styrene-butadiene, acrylate, polyester, phenol-epoxy resins, polysulfones, polyurethanes, individually or in combination, and polyethylene and polypropylene, which also contain other ingredients, such as charge control agents, waxes or flow aids, or can be modified with these additives afterwards. Furthermore, the dyes cleaned according to the invention are suitable as colorants in powders and powder coatings, in particular in triboelectric or electrokinetically sprayable powder coatings, which are used for the surface coating of objects made of, for example, metal, wood, plastic, glass, ceramic, concrete, textile material, paper or rubber Application come. Epoxy resins, carboxyl- and hydroxyl-containing polyester resins, polyurethane and acrylic resins are typically used as powder coating resins together with conventional hardeners. Combinations of resins are also used. For example, epoxy resins are often used in combination with carboxyl- and hydroxyl-containing polyester resins. Typical hardener components (depending on the resin system) are, for example, acid anhydrides, imidazoles and dicyandiamide and their derivatives, blocked isocyanates, bisacylurethanes, phenolic and melamine resins, triglycidyl isocyanurates, oxazolines and dicarboxylic acids.

In the following examples, percentages mean percentages by weight. The examples were carried out at room temperature (about 22 ° C.) and normal pressure.

example 1

100 g of an 8% aqueous solution of Cl Reactive Red 23 were mixed with 2 g of filter aid © Clarcel. Then a 10% aqueous sodium sulfide solution was slowly added dropwise until the potential on the potentiometer indicated a jump. The addition was stopped and stirring was continued for h. The mixture was then 2 g of water-washed ion exchanger (© Amberlite IRC748) added. The pH was kept at 4.0 to 4.5 with the addition of hydrochloric acid. The mixture was stirred for a further 2 h and then all insoluble constituents were filtered off. The ionic copper content fell from originally 18770 ppm to a value below 10 ppm.

Example 2

100 g 8% aqueous solution of C.I. Reactive Black 31 were with 2 g

Clarcel moved. Then a 10% aqueous sodium sulfide solution was slowly added dropwise until the potential on the potentiometer indicated a jump. The addition was stopped and stirring was continued for h. 2 g of water-washed ion exchanger (© Amberlite IRC748) was then added to the mixture. The pH was kept constant at 4.0 to 4.5 with the addition of hydrochloric acid. The mixture was stirred for 2 h and then all insoluble constituents were filtered off.

The ionic copper content dropped from originally 9,350 ppm to a value below 10 ppm.

Example 3

100 g of a 10% aqueous solution of C.I. Direct Blue 199 were made with 2 g

Clarcel added and the pH adjusted to 9. Then a 10% aqueous sodium sulfide solution was slowly added dropwise until the potential on the potentiometer reached one

Jump indicated. The addition was stopped and stirring was continued for h. The

The mixture was then 0.5 g of water-washed ion exchanger

The ionic copper content decreased from originally 180 ppm to a value below 10 ppm.

Claims

claims:

1) Process for removing free heavy metal ions and polyvalent metal ions from dye solutions, characterized in that the aqueous dye solution is first brought into contact with a sulfidic precipitant, the precipitated heavy metal sulfide is filtered off, and then the dye solution treated in this way with a chelating ion exchange resin containing and iminodiacetate / or thiol groups.

2) Method according to claim 1, characterized in that the dye is a metallized, anionic dye from the group of direct, acid, reactive and disperse dyes.

3) Method according to claim 1 or 2, characterized in that the dye is a dye complexed with a metal from the group Cu, Fe, Co, Ni, Cr, Zn, Mn and Al.

4) Method according to one or more of claims 1 to 3, characterized in that the dye is a copper complex dye.

5) Method according to one or more of claims 1 to 4, characterized in that the concentration of the dye in the dye solution is 1 to 30 wt .-%.

6) Method according to one or more of claims 1 to 5, characterized in that the dye solution to be cleaned contains 50 to greater than or equal to 10000O ppm of free heavy metal ions or polyvalent metal ions.

7) Method according to one or more of claims 1 to 6, characterized in that the sulfidic precipitant is an alkali metal sulfide, alkali metal hydrogen sulfide or alkali metal polysulfide. 8) Method according to one or more of claims 1 to 7, characterized in that sulfidic precipitant dissolved in water is added to the dye solution in an amount which corresponds approximately to the equivalent amount of the metal cations to be precipitated.

9) Method according to claim 8, characterized in that the metering of the sulfidic precipitant is controlled with a potentiometer.

10) Method according to one or more of claims 1 to 9, characterized in that the treatment of the dye solution with the ion exchange resin is carried out by stirring together for 10 minutes to 24 hours.

11) Method according to one or more of claims 1 to 9, characterized in that the dye solution in the upstream or downstream is passed over one or more columns which are filled with the ion exchange resin.

12) Method according to one or more of claims 1 to 11, characterized in that the dye solution is additionally desalted by reverse osmosis or a dye solution desalted by reverse osmosis is used.