EP2100912A1 - Use of polymers for modifying the surface tension of secure particles - Google Patents

Abstract

Use of a polymer in the form of polymerized units comprising: (a) a monomer containing amide unit (I), (b) a monomer containing amide unit (II); (c) acrylic and/or methacrylic acid; and/or (d) further monomers comprising 3-6C ethylenically unsaturated carboxylic acids such as crotonic acid, maleic acid, maleic acid anhydride, fumaric acid, itaconic acid or their salts or half esters, or sulfonic acid compound (III) or their salts, preferably alkali metal- and ammonium salts for dispersing solid particles in liquid, preferably aqueous media, is claimed. Use of a polymer in the form of polymerized units comprising: (a) a monomer containing an amide unit of formula (H 2C=CR 1>-CO-NH-R 2>-N +>R 3>R 4>R 5>X ->) (I), (b) a monomer containing an amide unit of formula (H 2C=CR 6>-CO-NR 7>R 8>) (II); (c) acrylic and/or methacrylic acid; and/or (d) further monomers comprising 3-6C ethylenically unsaturated carboxylic acids such as crotonic acid, maleic acid, maleic acid anhydride, fumaric acid, itaconic acid or their salts or half esters, or sulfonic acid compound of formula (H 2C=CR-CO-NH-CR1aR2aR3a-SO 3H) (III) or their salts, preferably alkali metal- and ammonium salts for dispersing solid particles in liquid, preferably aqueous media, is claimed, where the polymer is water-soluble at 20[deg] C, and the amount of the component (c) is not more than 25 wt.%, R 1>H or 1-4C-alkyl; R 2>1-12C alkylene; R 3>-R 5>H, 1-18C-alkyl or phenyl residue; X ->anions from the group of halo, sulfate or alkyl sulfate for hydroxide, phosphate, acetate, formate or ammonium; R 6>R 1>; R 7>, R 8>H, 1-4C alkyl or 3-6C cycloalkyl; and R, R1a-R3a : H or 1-4C alkyl. Provided that R 7>and R 8>are not simultaneously represents a hydrogen atom. Independent claims are included for: (1) the solid particles, produced by contacting carrier particles in an aqueous medium with the polymer, where the polymer remains in the aqueous medium and after treatment the solid particles are separated, dried or left the particles in the medium; and (2) a method for galvanic or autocatalytic metal deposition on metal surfaces, preferably for nickel plating of metal surfaces, comprising adding aqueous nickel solution containing at least one nickel salt, organic acid and inorganic phosphorus compound to an aqueous dispersion of boron nitride particles, and contacting the solution with the metallic surface until dispersion layer from metal and boron nitride particles are separated.

Description

The present invention relates to the change in the surface charge of solid particles measured via their zeta potential, and the use of such modified particles for the preparation of stable suspensions, for example in galvanic processes and as additives in lubricant compositions, in organic solvents, in polymeric materials, as flotation or as Auxiliary in aqueous slurries of clay minerals or in cosmetic or pharmaceutical compositions.

Various applications for solid particles are known in the art, which are dispersed in liquid, preferably aqueous media. These include, for example, dyes which contain dispersed pigments, but also dispersed fillers in polymers or dispersions in the field of pharmaceuticals, cosmetics or detergents and cleaners are known. Also in the manufacture of ceramics, clay dispersions (the so-called slip) are used. In the flotation, for example of ores also dispersions are used. A further technical example of dispersions occurs in the galvanization of metal surfaces (or according prepare other surfaces): For example, boron nitride (BN) is used in the galvanic nickel plating of metal surfaces in dispersed form in the galvanic bath, as the BN then together with the nickel the metal surface precipitates and improves the physical properties of the nickel layer. Dispersions are systems of several phases, one of which is dispersed continuously ( dispersing agent ) and at least one more (dispersed phase, dispersant ). Examples of dispersions are emulsions (liquid phases insoluble in one another), aerosols or the suspensions in question in the form of dispersed solid, preferably non-metallic, inorganic particles in a liquid phase. A molar dispersion is the molar-disperse distribution of one substance in another, ie here is a real solution. The energy for producing a dispersion can be supplied, for example, chemically, electrochemically, electrically or mechanically (by grinding, by means of ultrasound, etc.). In principle, dispersions are prone to phase separation (sedimentation), so that stabilization with emulsifiers or protective colloids is carried out during their preparation and storage. Alternatively or in addition thereto, the electrostatic repulsion in the same direction charged pigment or polymer particles is also exploited (electrostatic stabilization).

In practice, there is often the problem that the particles can be dispersed poorly or not at all in an aqueous or other liquid medium: In many cases, surfactants are used as dispersants for the preparation or stabilization of the dispersions. There is therefore a continuing need to better disperse solid inorganic particles in liquids, preferably in aqueous media. The reason for the difficulties in the dispersion, d. H. the fine distribution of the solid particles occurs in the liquid medium is to be seen in the fact that the surface charge on the surface of the particles, a uniform incorporation into the solvent, preferably not water or only partially.

However, solution approaches are already known in the prior art. So describe the US 4,098,654 and US 4,302,374 the use of nonionic surfactants to stabilize PTFE particles. In the US 145,517 Chemical plating processes are described in which surfactants based on organic non-fluorinated compounds are used to stabilize finely divided solids in a plating bath. However, there is still the need to improve the stabilization of solid particles not only in the field of galvanic baths but to generally optimize the dispersing behavior of solids in liquid media.

It has surprisingly been found that certain water-soluble polymers are suitable for improving the dispersing properties of solid particles, preferably inorganic particles, in liquid, preferably in aqueous media.

1. a) H₂C=CR¹-CO-NR-R²-N⁺R³R⁴R⁵ X^-
   wobei R¹ für ein Wasserstoffatom oder einen Alkylrest mit 1 bis 4 C-Atomen steht, R² für einen linearen oder verzweigten Alkylenrest mit 1 bis 12 C-Atomen und R³, R⁴, R⁵ unabhängig voneinander ein Wasserstoffatom, einen Alkylrest mit 1 bis 18 C-Atomen oder einen Phenylrest bedeuten, und X^- für ein Anion aus der Gruppe der Halogene, Sulfate bzw. Alkylsulfate, für Hydroxid, Phosphat, Acetat, Formiat oder Ammonium steht, und
2. b) H₂C=CR⁶-CO-NR⁷R⁸
   wobei R⁶ für ein Wasserstoffatom oder einen Alkylrest mit 1 bis 4 C-Atomen steht und R⁷ und R⁸ jeweils unabhängig voneinander für ein Wasserstoffatom, einen Alkylrest mit 1 bis 4 C-Atomen oder einen C3-C6 Cycloalkylrest stehen, mit der Maßgabe, dass R⁷ und R⁸ nicht gleichzeitig für ein Wasserstoffatom stehen, und
3. c) Acryl- und/oder Methacrylsäure und / oder
4. d) weitere Monomere aus der Gruppe der C3-C6 einfach ethylenisch ungesättigten Carbonsäuren wie Crotonsäure, Maleinsäure, Maleinsäureanhydrid, Fumarsäure, Itaconsäure, sowie deren Halbester, und Salze oder H₂C=CR-CO-NH-CR'R"R"'-SO₃H sowie deren Salze, insbesondere die Alkalimetall- und Ammoniumsalze, wobei R, R', R" und R"' unabhängig voneinander für ein Wasserstoffatom oder einen Alkyl(en)rest mit 1 bis 4 C-Atomen steht,

enthalten, mit der Maßgabe, dass in dem Polymer das Monomere c) in Mengen von höchstens 25 Gew.-% bezogen auf das Polymer enthalten ist, zur Dispergierung fester Teilchen in flüssigen, vorzugsweise wässerigen Medien.A first subject of the present application relates to the use of at 20 ° C in water-soluble polymers which in the form of polymerized units at least one monomer

1. a) H ₂ C = CR ¹ -CO-NR-R ² -N ⁺ R ³ R ⁴ R ⁵ X ^-
   where R ^{1 is} a hydrogen atom or an alkyl radical having 1 to 4 C atoms, R ^{2 is} a linear or branched alkylene radical having 1 to 12 C atoms and R ³ , R ⁴ , R ⁵ are each independently a hydrogen atom, an alkyl radical 1 to 18 carbon atoms or a phenyl radical, and X ^{- represents} an anion from the group of halogens, sulfates or alkyl sulfates, for hydroxide, phosphate, acetate, formate or ammonium, and
2. b) H ₂ C = CR ⁶ -CO-NR ⁷ R ⁸
   wherein R ^{6 represents} a hydrogen atom or an alkyl group having 1 to 4 carbon atoms and R ⁷ and R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 4 C atoms or a C 3 -C 6 cycloalkyl group, with the proviso in that R ⁷ and R ^{8 are} not simultaneously a hydrogen atom, and
3. c) acrylic and / or methacrylic acid and / or
4. d) other monomers from the group of C3-C6 monoethylenically unsaturated carboxylic acids such as crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid and their half-esters, and salts or H ₂ C =CR-CO-NH-CR'R "R"' -SO ₃ H and salts thereof, in particular the alkali metal and ammonium salts, where R, R ', R "and R"' independently of one another represent a hydrogen atom or an alkyl (ene) radical having 1 to 4 C atoms,

with the proviso that in the polymer, the monomer c) is contained in amounts of at most 25 wt .-% based on the polymer, for the dispersion of solid particles in liquid, preferably aqueous media.

The polymers are known compounds known in the art EP 1 767 554 A1 the applicant are described, wherein in the document, a manufacturing method for these polymers is disclosed.

There are now preferred such polymers according to the above description, the weight fraction of monomers c) is less than 15 wt .-% and in particular equal to or less than 10 wt .-%. A preferred weight range for the monomer c) is 5 to 25, preferably 5 to 15 and in particular from 5 to 10 wt .-%, each based on the total weight of the polymer.

The polymers of the invention comprise as polymerized monomers at least three different monomers a) to d). In this case, all polymers are included which contain either the monomer units a), b) and c), or a), b) and d) or a), b), c) and d) side by side. It is also within the meaning of the present invention possible to use mixtures of the listed polymers.

Monomer component a)

The monomers of this type follow the general formula

H ₂ C = CR ¹ -CO-NH-R ² -N ⁺ R ³ R ⁴ R ⁵ X ^-

where R ^{1 is} a hydrogen atom or an alkyl radical having 1 to 4 C atoms, R ^{2 is} a linear or branched alkylene radical having 1 to 12 C atoms and R ³ , R ⁴ , R ⁵ are each independently a hydrogen atom, an alkyl radical 1 to 18 carbon atoms or a phenyl radical, and X is an anion from the group of halogens, sulfates or alkyl sulfates, for hydroxide, phosphate, acetate, formate or ammonium. Particular preference is given to those monomers of type a) in which R ^{1 is} a methyl radical, R ^{2 is} a CH ₂ -CH ₂ -CH _{2 group} , and R ³ , R ⁴ and R ^{5 are} each methyl. X ^- represents a suitable counterion such as halide, hydroxide, sulfate, hydrogen sulfate, phosphate, formate or acetate, preferably chloride. These are known to those skilled in the art under the name 3-trimethylammoniumpropylmethacrylamidchlorid (MAPTAC).

Monomer component b)

The second, necessarily in the polymers of the invention contained monomer is a nitrogen-containing ethylenically unsaturated compound of the following general formula:

H ₂ C = CR ⁶ -CO-NR ⁷ R ⁸

where R ^{6 is} a hydrogen atom or an alkyl radical having 1 to 4 C atoms and R ⁷ and R ⁸ , each independently of one another represent a hydrogen atom, an alkyl radical having 1 to 4 C atoms or a C 3 -C 6 cycloalkyl radical, with Provided that R ⁷ and R ^{8 are} not simultaneously a hydrogen atom. These are therefore alkylacrylamides. Particular preference is given to N-isopropylacrylamide, also known by the abbreviation NIPAM.

Monomer component c)

As the third component c) ethylenically unsaturated acids and their salts, such as acrylic or methacrylic acid are suitable. Acrylic acid (AA) is the most preferred monomer here. Particularly suitable salts are their alkali metal and ammonium salts.

Monomer component d)

Further monomers may additionally or instead of component c) be contained in the polymers according to the invention as building blocks. They are selected from the group of C3-C6 monoethylenically unsaturated carboxylic acids such as crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid and their half-esters, and salts or H ₂ C =CR-CO-NH-CR'R "R"'- SO ₃ H and their salts, in particular the alkali metal and ammonium salts, where R, R ', R "and R"' independently of one another represent a hydrogen atom or an alkyl (ene) radical having 1 to 4 C atoms. Particularly preferred is the monomer of the type d), the molecule having the general formula H ₂ C = CR-CO-NH-CR'R "R '" - SO ₃ H, in particular a derivative, the 2-acrylamido-2 methylpropanesulfonic acid (AMPS) is emphasized.

There may be further monomer units in addition to the above-mentioned a) to d) in the polymers of the invention, in which case nitrogen-containing monomers are particularly preferred. Examples are dimethyldiallylammonium chloride (DADMAC), 2-dimethylaminoethyl (meth) acrylate (DMAE (M) A), 2-diethylaminoethyl (meth) acrylate, 3-dimethylaminopropyl (meth) acrylamide (DMAP (M) A), 3-dimethylamino-2, 2-dimethylpropyl acrylamide (DMADMPA), as well as the optionally resulting therefrom by protonation or quaternization derivatives, in particular 2-trimethylammoniumethyl (meth) acrylate chloride and 3-Diethylmethylammoniumpropylacrylamidchlorid.

The polymers used according to the invention are water-soluble, ie that at least 0.1 g of the polymer in 100 ml of water at 20 ° C are soluble. The polymers are ampholytic, ie the polymers have both acidic and basic hydrophilic groups and behave acidic or basic depending on the condition. The polymers of the invention preferably have a mean molecular weight (weight average molecular weight, M _w), measured by gel permeation chromatography aqueous (GPC) with light scattering detection (SEC-MALLS), in the range of 10,000 to 500,000 Da. Preferably, the molecular weight of the polymers is between 50,000 and 350,000 Da and in particular between 100,000 and 250,000 Da. A particularly preferred range may be between 110,000 and 140,000 Da.

The various monomer building blocks a) to d) preferably coexist in certain selected proportions. Preference is given in each case to those polymers which contain the component b) in excess (both based on moles and on Weight of the components) to components a) and c). Preferred here are polymers in which the molar ratio between the monomers a), b) and c) in the range of 1: 10: 1 to 5: 10: 5 and preferably in the range of 4: 10: 1 to 4: 10: 3 and especially in the range of 3: 8: 2 to 3: 8: 1.

Particular preference is given in particular to those polymers in which the molar ratio between components a) and b) is from 1:10 to 1: 1 and in particular from 1: 5 to 1: 1.

Based on mol% of the respective monomers, preferably 20 to 30% of monomer a), 50 to 70% of monomer b) and 10 to 20% of monomer c) are contained. If, instead of component c), the monomer component of type d) is present, the same conditions apply analogously. However, particularly preferred polymers may be those which contain both monomers of type c) and of type d) side by side. Preferably, the monomer units c) and d) are then present in a molar ratio of 2: 1 to 1: 2, more preferably in a ratio of 1: 1, side by side. Particularly preferred polymers with four different monomer building blocks have molar ratios a): b): c): d) of 2: 4: 1: 1 to 1: 10: 1: 1. A particularly preferred ratio is 3: 8: 1: 1.

Preferred polymers are in particular those in which the monomer a) is selected from those compounds of the general formula in which R ^{1 is} a methyl group, R ^{2 is} an alkylene radical having 3 C atoms, R ³ , R ⁴ and R ^{5 are} each methyl radicals and X is chloride, the monomer b) is selected from those compounds of the general formula in which R ⁶ and R ^{7 are} a hydrogen atom and R ^{8 is} an isopropyl radical and monomer c) is acrylic acid. Also preferred are polymers in which the monomer a) is selected from those compounds of the general formula in which R ^{1 is} a methyl group, R ^{2 is} an alkylene radical having 3 C atoms, R ³ , R ⁴ and R ^{5 are} each methyl and X is are chloride, the monomer b) is selected from those compounds of the general formula in which R ⁶ and R ^{7 are} a hydrogen atom and R ^{8 is} an isopropyl radical and monomer c) for H ₂ C = CR-CO-NH-CR ' R "R"'- SO ₃ H and salts thereof, in particular the alkali metal and ammonium salts, where R, R', R "and R"'independently of one another represent a hydrogen atom or an alkyl radical having 1 to 4 C -Atoms stands, is.

Particularly preferred, and therefore a separate and independent object of the present invention, is a 20 ° C water-soluble polymer containing at least three different monomers a), b), c) and / or d), it being true that the monomers a) and b) must necessarily be present in a molar ratio of 1: 1 to 1:10 and in addition the monomers c) and / or d), wherein as monomer a) the 3-trimethylammonium propylmethacrylamidchlorid (MAPTAC), as monomer b) the N-isopropylacrylamide (NIPAM), as monomer c) acrylic acid (AA) and / or methacrylic acid (MA), as Monomer d) 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS) are selected, with the proviso that in the water-soluble polymer, the monomer c) in amounts of at most 25 wt .-% based on the total weight of the water-soluble polymer is. There are preferred such polymers according to the above description, the weight fraction of monomers c) is less than 15 wt .-% and in particular equal to or less than 10 wt .-%. A preferred weight range for the monomer c) is 5 to 25, preferably 5 to 15 and in particular from 5 to 10 wt .-%, each based on the total weight of the polymer.

These polymers can also be described by the following formula scheme:

The indices m, n, p and q represent the number of monomer building blocks NIPAM, MAPTAC, AA and AMPS in the polymer molecule. However, the sequence of the building blocks in the polymers according to the invention is generally not necessarily predetermined; rather, all sequences of the individual building blocks, whether blocks of the individual monomers or their purely statistical sequence in the molecule, are encompassed.

In this predefined polymer type, those derivatives are particularly preferred which contain the monomers MAPTAC, NIPAM and AMPS in weight ratios of from 25 to 50% MAPTAC, 40 to 75% NIPAM and 1 to 15% AMPS polymerized, with the proviso that the percent summer gives 100.

An independently preferred polymer is one which contains the monomers MAPTAC, NIPAM and AA polymerized in the weight ratios of 25 to 50% MAPTAC, 40 to 75% NIPAM and 1 to 15% AA, with the proviso that the percentages of the percents are 100 results. Finally, independently of this, a water-soluble polymer at 20 ° C. is also preferred in that it contains the monomers MAPTAC, NIPAM, AA and AMPAS in a weight ratio of 25 to 45% MAPTAC, 40 to 70% NIPAM, 1 to 15% AA and 1 to 15% AMPS contains, provided that the sum of the percentage shares 100.

Polymers as described above can be made by polymerization processes known to those skilled in the art. They can be prepared, for example, by solution polymerization or bulk polymerization. Preferably, they are prepared by solution polymerization, ie, a polymerization of monomers in solvents and / or water, in which both the monomers and the polymers resulting from them are soluble. Furthermore, the polymerization can be carried out with presentation of the total amount of monomer or with monomer feed, batchwise, semicontinuously or continuously. Preferably, the polymerization is carried out as a batch polymerization with or without monomer feed.

The above-described water-soluble polymers have the property of measuring the surface charge of solid particles measured e.g. via their zeta potential of an aqueous dispersion of the particles to reload.

The measurement of the zeta potential is a common method for the characterization of solid / liquid dispersions. Dispersed particles can become electrically charged, for example by adsorption of ions on their surface. As a result, an electric double layer forms on the surface of these electrically charged particles, which is firmly bound to the particles and causes an apparent volume increase. This solid layer is enveloped by a mobile and diffused ion layer. The potential ψ ₀ at the particle surface now drops linearly within the solid ion layer with the thickness δ to the value ψ _δ in order to return approximately exponentially in the diffuse layer to the value 0. The potential difference between the inner solid ion layer ψ _δ and the Point within the diffuse ion layer, where the potential has decreased to 1 / e • ψ _δ , is called the zeta potential.

ζ =

Zeta-Potential (in mV)

s =

Dielektrizitätskonstante des Dispersionsmittels

ν =

elektrophoretische Wanderungsgeschwindigkeit ( in cm/s)

η =

Viskosität des Dispersionsmittels (Poise, 1 Poise = 0,1 Pa • s)

E =

Feldstärke (in mV)

f =

Zahlenfaktor (Reibungsfaktor), der von der Form der Teilchen, ihrer Leitfähigkeit und der Größe der Teilchen im Vergleich zur Dicke der diffusen Doppelschicht abhängt

The zeta potential can be determined directly from the direction of migration and the velocity of the dispersed particles in the electric field, based on the following relationship: $$\zeta =\frac{f\cdot \mathit{\pi }\mathit{\cdot }\mathit{\nu }\mathit{\cdot }\mathit{\eta }}{e\cdot \epsilon }$$

ζ =

Zeta potential (in mV)

s =

Dielectric constant of the dispersant

ν =

electrophoretic migration rate (in cm / s)

η =

Viscosity of the dispersing agent (poise, 1 poise = 0.1 Pa · s)

E =

Field strength (in mV)

f =

Number factor (friction factor), which depends on the shape of the particles, their conductivity and the size of the particles compared to the thickness of the diffuse double layer

Depending on the size of the particles to be examined, the migration rate is measured either by light microscopic observation or, in particular in the case of smaller particles, by means of laser correlation spectroscopy.

The polymers used according to the invention cause the respective treated particles to undergo a transloading to the surface, for example from a positive to a negative charge value, or vice versa. Preferred are changes from a negative to a positive zeta potential of the particles.

An object of the present application relates to solid particles preparable by contacting a carrier particle in an aqueous medium with a polymer as described above. For this purpose, the solid particles in an aqueous medium are contacted with a polymer as described above with the polymer itself in the aqueous solution and the polymer solution mixed with the solid particles. After the treatment, the solid particles are separated from the solution, for example by filtration and the separated particles are then dried. However, it is also conceivable and according to the invention to leave the particles dispersed in the aqueous polymer solution and to use them further.

Preferably, the polymer solution in the treatment of the solid particles is carried out at a temperature of 10 to 90 ° C, preferably 15 to 35 ° C and especially at 18 to 30 ° C.

The pH during the process is preferably in the range of <1 to 14, preferably between 1 and 14 and can, especially in Galavin baths particularly preferably in the acidic range, in particular in the range of 1 to 5 and advantageously in the range of 1 to 3 lie. Therein, the method according to the invention advantageously differs from the prior art, which uses surfactants which are generally no longer stable under such extreme conditions.

The particles which are preferably treated with the polymers preferably have a diameter between 10 and 0.00001 mm, with particles with diameters of 1 to 0.0001 mm or 0.1 to 0.001 mm being preferred. Also preferred are those particles in which an aqueous solution of the polymer is used which has a weight fraction of polymer of from 0.01 to 30% by weight, preferably from 0.1 to 15 and in particular from 1 to 10% by weight. %, in each case based on the total weight of the aqueous solution.

The particles according to the invention are preferably inorganic (preferably at room temperature = 21 ° C.) solid particles selected, in particular, from the group of oxides, hydroxides, carbides, borides, sulfides or nitrides. Particularly preferred are the nitrides and carbides, with very particular preference being given to boron nitride (BN), silicon carbide (SiC) and boron carbide (B ₄ C). The particles are preferably non-metallic, inorganic particles.

The solid particles thus translocated on the surface, which are also the subject of the present invention, and the aqueous dispersions of such particles can preferably be used in galvanic processes (electrolytic or chemical) or as additives in lubricant compositions, or in organic solvents or in polymeric materials. However, such particles according to the invention can also be used as flotation auxiliaries or as aids for the slurry of clay minerals.

Electroplating is generally understood to mean the electrochemical surface treatment of materials, ie the electrolytic deposition of metallic (or even non-metallic) thin layers for the purpose of beautification, protection against corrosion, the production of composite materials with improved properties and the like. Electroplating encompasses the two main areas of galvanostasis and electroforming. Electroforming is used to manufacture or reproduce articles by electrolytic deposition. For this purpose, the original form first an impression (negative, mold) of gypsum, wax, gutta-percha, silicone rubber, low-melting metal alloys, etc. produced. The casting is rendered superficially electrically conductive (by chemical precipitation or vapor deposition of metals) and then coated as a negative pole in the plating liquid with the metal to be deposited (eg Cu, Ni, Ag, etc., plus pole). After completion of the electrolysis, the metal layer formed can be lifted off the mold u. if necessary pour out with filler for reinforcement. Used for the production of printing substrates in high-pressure printing, for copying works of art, manufacturers of record matrices and other technical casting molds. In contrast, the much more important, also known as electroplating Galvanostegie a method of coating objects with mostly very thin, protective and beautifying coatings of silver, gold, nickel, chromium, copper and the like on less valuable documents (eg iron) using the electric current. Examples are silvering, gilding, chrome plating, etc. It is between electroless, ie with chem. Reducing agents working methods and electrolytic processes ("electroplating") distinguished.

If the article to be plated is electrically nonconductive, it must be made conductive. The metallization of the article can also be done in vacuum (ion plating) or melting. It is also known that surface cavities of electrically non-conductive materials are provided with nucleating agents, for example palladium chloride. Galvanization in the broadest sense also includes preparatory processes, such as chemical and electrolytic degreasing, pickling, polishing (in particular so-called electropolishing) and dyeing, and in particular the chemical deposition of metal and oxide layers. In order to obtain a well-adhering electrodeposition, the workpieces to be plated must be thoroughly cleaned before being introduced into the plating bath and treated with the means of metal degreasing. The galvanic baths are divided into acidic and alkaline baths. The acid baths contain sulfates, chlorides, fluoroborates and sulfamates of the metals to be deposited, while the alkaline baths are based on hydroxo- or cyano complexes or diphosphates. In the further developed gloss galvanization is obtained as a result of using certain additives that have a leveling effect (brighteners), immediately a shiny galvanic coating, the subsequent polishing often redundant. The workup of spent galvanizing u. the removal of surfactant, metal, salt and acid residues from the Wastewater not only serves to recover valuable raw materials (recycling), but also to clean water and thus protect the environment. Since the dispersion separation of particles in metal layers takes place under chemically extreme conditions, for example very low or very high pH values and high salt loads in the electrolyte, most surface-active surfactants precipitate from the outset. In particular, the surfactants necessary for the production of dispersion deposits are therefore often aromatic surfactants or fluorinated surfactants and, precisely because of their robustness, represent a considerable burden on the environment.

A further subject of the application is therefore directed to a preferably surfactant-free process for galvanic or autocatalytic metal deposition on metallic surfaces, for example for the nickel plating of metallic surfaces, which comprises adding to an aqueous nickel solution containing at least one Ni salt, an organic acid and a inorganic phosphorus compound is an aqueous dispersion of boron nitride particles (preferably hexagonal BN) prepared as described above and then contacting this solution with the metallic surface until a metal-boron nitride particle dispersion layer has been deposited thereon ,

Furthermore, the solid particles for the purposes of the present invention are to be used as additives in lubricant compositions, in organic solvents, in pharmaceutical preparations, in cosmetic compositions or as flotation auxiliaries. Furthermore, such particles may find application in the matrix of polymeric materials (duroplastic or thermoplastic polymers), preferably in dispersed fillers in polymers, or they may find utility as an aid to the aqueous slurry of clay minerals.

The latter relates to the production of the so-called slip, which is used to produce ceramic materials, preferably porcelain. The main raw materials for ceramics are clay minerals (clay, kaolin). While the kaolins, mostly from primary deposits, have to be freed from coarse fractions prior to processing by sludge, the clays, from secondary deposits already leached by nature, can often be processed as extracted from the soil. Mordants are used as additives to reduce shrinkage during drying and firing (eg quartz, sand, ground burnt clay = chamotte), flux to lower the sintering temperature (eg feldspar) and optionally colorants (certain metal oxides, see ceramic pigments). In the dry and Half-wet preparation, all mixture components are dried, optionally crushed, mixed and moistened for shaping with water or wet steam as needed. In wet processing, the raw materials are wet-milled in drum mills or transferred by mixing with water in mixing whiskers in aqueous suspensions. This flowable so-called slip can be further processed by casting or, for example, be dewatered in chamber filter presses up to the plastically deformable state. The use of the water-soluble polymers in the sense of the technical teaching described here leads to improved stabilization of the clay particles in the slurry, the process according to the invention allowing, for example, spray-drying to reduce the transport amount and redispersing at the place of use of the clays coated in this way. Furthermore, higher solids contents in the suspension can be adjusted with particles coated in this way with the same fluidity, which both lowers the amount of water to be evaporated and thus the energy consumption during drying, and also improves the processing.

Flotation is known to be a separation process for the treatment of ores, coal, salts or wastewaters. The flotation makes the different interfacial tension of solids to liquids (mostly water) and gases (mostly air) - i. the different wetting in the water of suspended particles - use; Phenomena of adhesion, zeta potential and, in general, electrochemical double layer play a role at the interfaces. For example, metal sulfides, many metal oxides, heavy metals, carbon and diamond are readily wetted by water repellent (hydrophobic) species such as aliphatic or aromatic hydrocarbons, gait (dead rock), namely quartz, silicates, phosphates, sulfates, carbonates, halides and the like. Like. However, slightly of water u. hydrophilic substances.

The flotation is based on the fact that wetted particles sink, but not wetted - with a grain size between 10 and 500 microns - to accumulate on the suspension (turbid) led air bubbles, to the surface migrate (creaming) and can be removed together with the foam , The wettability of the substances to be separated can be selectively influenced by the addition of flotation auxiliaries. These are chemicals that improve the wettability of various mineral surfaces. This function can also be used according to the invention polymers according to the above Description exercise. Solid, wetted with the polymers particles are suitable to improve flotation, for example, by facilitating the separation of the solids from the aqueous phase, and thus increase, for example, the yield of floated materials.

Examples 1. Preparation of a polymer according to the invention

A terpolymer according to the invention was prepared as follows: 12.4 g of MAPTAC, 1.4 g of acrylic acid and 50 g of water were mixed. The pH of the aqueous mixture was adjusted in the range of 6.5 to 7.5. Then, 8.5 g of NIPAM and 23 g of isopropanol were added, and this mixture was heated to 65 ° C. Then, as a starter, 0.15 g of 2,2'-azobis (2-amidinopropane) dihydrochloride was added and the reaction started. The mixture is heated to about 80 ° C. After the reaction had elapsed, the azeotrope water / isopropanol was distilled off at 80-100 ° C. The concentration of the resulting polymer solution was about 22 wt .-%. The pH of the solution was 5 to 7.5. The polymer had a molecular weight of 130,000 Da (measured by SEC-MALLS).

2. Preparation of inorganic particles according to the invention

Samples of boron nitride, silicon carbide, and boron carbide powders were tested: to this was added an aqueous solution containing 5% by weight of a polymer according to the synthesis under "1." produced. Each 1.0 g of the powder samples were suspended in each 99.0 g of the aqueous polymer solution and stirred for 72 hours. Subsequently, the suspension was filtered off. The residue was washed with water and dried at 80 ° C for 12 hours. The dry residue was subsequently suspended in 100 ml of water.

3. Application engineering investigations agglomeration

Compared to untreated powder samples, the treated samples agglomerated only very weakly in the aqueous suspension. Exemplary is in illustration 1 this effect is shown photographically for a boron nitride powder with 0.5 μm grain size diameter. The polymer-treated boron nitride powder is much more stable in levitation than the untreated boron nitride powder.

Zeta-potential measurement

In addition, the zeta potential of the aqueous suspensions of boron nitride, silicon carbide, and boron carbide powders was determined (see Figure 2 ). The measurement was carried out with a Coulter DELSA 440 SX measuring device. It can be seen that the untreated particles have a negative surface charge, whereas the particles treated according to the invention have been reloaded and have a positive charge. A transhipment of the original surface charge has succeeded.

galvanization

The polymer-treated boron nitride from Example 1 was used in a chemical galvanization. The chemical Ni-electrolyte; which was used for the study consists of: nickel sulfate, acetic acid, sodium hypophosphite monohydrate and a stabilizer (commercial product: SurTech ^® 835). For deposition, 10 g of treated boron nitride were used per liter of nickel bath. Scanning electron micrographs show that there is no boron nitride in the deposited nickel layer without treatment ( Figure 3 ). Boron nitride pretreated with the polymer contains about 10-20% BN ( Figure 4 ).

Claims (20)

Use of water-soluble polymers at 20 ° C, which in the form of polymerized units at least one monomer a) H ₂ C = CR ¹ -CO-NH-R ² -N ⁺ R ³ R ⁴ R ⁵ X ^-
where R ^{1 is} a hydrogen atom or an alkyl radical having 1 to 4 C atoms, R ^{2 is} a linear or branched alkylene radical having 1 to 12 C atoms and R ³ , R ⁴ , R ⁵ are each independently a hydrogen atom, an alkyl radical 1 to 18 carbon atoms or a phenyl radical, and X ^{- represents} an anion from the group of halogens, sulfates or alkyl sulfates, for hydroxide, phosphate, acetate, formate or ammonium, and b) H ₂ C = CR ⁶ -CO-NR ⁷ R ⁸
wherein R ^{6 represents} a hydrogen atom or an alkyl group having 1 to 4 carbon atoms and R ⁷ and R ⁸ each independently represent a hydrogen atom, an alkyl group having 1 to 4 C atoms or a C 3 -C 6 cycloalkyl group, with the proviso in that R ⁷ and R ^{8 are} not simultaneously a hydrogen atom, and c) acrylic and / or methacrylic acid and / or d) other monomers from the group of C3-C6 monoethylenically unsaturated carboxylic acids such as crotonic acid, maleic acid, maleic anhydride, fumaric acid, itaconic acid, and their half-esters, and salts or H ₂ C = CR-CO-NH-CR'R "R '" -SO ₃ H and salts thereof, in particular the alkali metal and ammonium salts, where R, R ', R "and R"' independently of one another represent a hydrogen atom or an alkyl (ene) radical having 1 to 4 C atoms, with the proviso that in the polymer, the monomer c) is contained in amounts of at most 25 wt .-% based on the polymer,
for dispersing solid particles in liquid, preferably aqueous media. Use according to claim 1, characterized in that a water-soluble at 20 ° C polymer is used, containing at least three different monomers a), b), c) and / or d), wherein it is mandatory that the monomers a) and b) in the molar ratio of 1: 1 to 1: 10 must be included and in addition the monomers c) and / or d) are contained, wherein
as monomer a) the 3-trimethylammoniumpropylmethacrylamide chloride (MAPTAC),
as monomer b) the N-isopropylacrylamide (NIPAM),
as monomer c) acrylic acid (AA) and / or methacrylic acid (MA),
as monomer d) 2-acrylamido-2-methyl-1-propanesulfonic acid (AMPS)
with the proviso that in the water-soluble polymer, the monomer c) is contained in amounts of at most 25 wt .-% based on the total weight of the water-soluble polymer. Use according to at least one of Claims 1 or 2, characterized in that in the polymer the monomers MAPTAC, NIPAM and AMPS are polymerized in weight ratios of 25 to 50% MAPTAC, 40 to 75% NIPAM and 1 to 15% AMPS, with the proviso in that the sum of the percentages gives 100. Use according to at least one of Claims 1 to 3, characterized in that in the polymer the monomers MAPTAC, NIPAM and AA are polymerized in the weight ratios of 25 to 50% MAPTAC, 40 to 75% NIPAM and 1 to 15% AA, with the proviso that the sum of the percentage shares 100. Use according to at least one of claims 1 to 4, characterized in that in the polymer the monomers MAPTAC, NIPAM, AA and AMPS in the weight ratio of 25 to 45% MAPTAC, 40 to 70% NIPAM, 1 to 15% AA and 1 to 15 % AMPS, with the proviso that the sum of percentages equals 100. Use according to at least one of claims 1 to 5, characterized in that in the polymer, the molar ratio between the monomers a), b) and c) or d) in Range of 1: 10: 1 to 5: 10: 5 and preferably in the range of 4: 10: 1 to 4: 10: 3 and in particular in the range of 3: 8: 2 to 3: 8: 1. Use according to at least one of claims 1 to 6, characterized in that in the polymer, the molar ratio between the monomers a), b), c) and d) is 3: 8: 1: 1. Use according to at least one of claims 1 to 8, characterized in that in the polymer 20 to 30 wt .-% of monomer a), 50 to 70 wt .-% of monomer b) and 10 to 20 wt .-% of monomers c) and or d) are provided with the proviso that the sum of the units amounts to 100. Use according to at least one of claims 1 to 9, characterized in that the monomers c) and d) in the weight ratio of 1: 1 are present side by side in the polymer. Use according to at least one of Claims 1 to 10, characterized in that the polymers have an average molecular weight in the range from 10,000 to 500,000 Da, preferably from 50,000 to 350,000 Da and in particular from 100,000 to 250,000 Da. Use according to at least one of claims 1 to 11, characterized in that the particles are selected from inorganic compounds, preferably from the group of oxides, hydroxides, carbides, borides, sulfides or nitrides. Use according to at least one of claims 1 to 11, characterized in that the solid particles are selected from the group boron nitride (BN), silicon carbide (SiC), or boron carbide (B ₄ C). Use according to at least one of claims 1 to 12, characterized in that the solid particles have diameters between 10 and 0.00001 mm. Solid particles preparable by contacting a carrier particle in an aqueous medium with a polymer as described in claim 1 wherein the polymer is in an aqueous solution and after treatment separates and dries the solid particles or these particles directly in the solution leaves. Particles according to Claim 14, characterized in that an aqueous solution of the polymer is used for the preparation which has a weight fraction of polymer of from 0.01 to 30% by weight, preferably from 0.1 to 15 and in particular from 1 to 10% by weight. -%, in each case based on the total weight of the aqueous solution. Particles according to at least one of claims 14 to 15, characterized in that during the preparation of the step of contacting the particles with the polymer solution at temperatures of 10 to 90 ° C, preferably from 15 to 35 ° C and in particular from 18 to 30 ° C performs. Particles according to at least one of claims 14 to 16, characterized in that the solid particles are dispersed in the preparation in the polymer solution. Use of solid particles, prepared according to claim 14, in galvanic processes (electrolytic or chemical) or as an additive in lubricant compositions, in organic solvents, in polymeric materials, or as flotation aids or as aids for the slurry of clay minerals. Use according to claim 18, characterized in that boron nitride is used as solid particles. Process for galvanic or autocatalytic metal deposition on metallic surfaces, for example for nickel plating of metallic surfaces, characterized in that an aqueous dispersion of boron nitride particles is added to an aqueous nickel solution containing at least one Ni salt, an organic acid and an inorganic phosphorus compound there are, which have been prepared according to claim 14, and then contacting this solution with the metallic surface until a metal and boron nitride particle dispersion layer has been deposited thereon

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