EP3368204A1

EP3368204A1 - Metal dispersion with increased stability

Info

Publication number: EP3368204A1
Application number: EP16781113.2A
Authority: EP
Inventors: Alexander Rösch; Carsten Schaefer
Original assignee: Clariant International Ltd
Current assignee: Clariant International Ltd
Priority date: 2015-10-30
Filing date: 2016-10-12
Publication date: 2018-09-05
Also published as: JP2018535321A; US20180340083A1; IL258734A; TW201731587A; WO2017071949A1; CN108348884A; CA3003504A1; TWI697355B; KR20180077252A

Abstract

The invention relates to metal dispersions containing 50 to 80 wt.% of silver nanoparticles, 15 to 45 wt.% of water, and a dispersant, said dispersant containing copolymers that contain 1 to 99 wt.% of structural units of the formula (1), in which R represents hydrogen or C₁-C₆-alkyl, A represents C₂-C₄ alkaline groups, and B represents C₂-C₄ alkaline groups, with the proviso that A differs from B, and m, n independently of each other represent a whole number from 1 to 200, and 1 to 99 wt.% of structural units of the formula (2), in which Xa represents an aromatic or aliphatic group with 1 to 30 C atoms, said group optionally containing one or more heteroatoms, for example 1, 2, or 3 heteroatoms, of N, O, and S, Z_a represents H or (C₁-C₄)-alkyl, Z_b represents H or (C₁-C₄)-alkyl, and Z_c represents H or (C₁-C₄)-alkyl.

Description

Metal dispersion with increased stability

The present invention relates to the use of copolymers which contain metal particulate sols having a metal particle content of 50 to 80% by weight.

stabilize.

Metal particles within the meaning of the present invention include nanoparticles and submicroparticles. Nanoparticles in the sense of the present invention are defined as particles that are smaller than 100 nm in at least one dimension. Microparticles are particles that are between 1 pm and 1000 prn in all three dimensions. Submicroparticles are defined as particles which are greater than 100 nm in all three dimensions and which are smaller than 1 μm in at least one dimension. A sol or colloid is a dispersion of nano- or sub-microparticles in a liquid.

Important criteria for the properties and applications of

Nanoscale and submicroscale metal particles provide, inter alia, the average particle size, the particle size distribution, the colloid-chemical

Stability of the dispersion, the processing and physico-chemical

Characteristics of the particles.

The prior art discloses various methods for producing metallic nanoparticles. A well-known principle is the direct chemical reduction of dissolved metal ions in the liquid phase. The aim of many variants of this method is the production of colloid-chemically stable dispersions of metallic nanoparticles with narrow particle size distribution and defined surface properties.

The term "colloidally chemically stable" means that the properties of the colloidal dispersion or of the colloids hardly change even during the usual storage time before the first application or a break between two production cycles

Flocculation of the colloids take place, which negatively affects the product quality would affect. Usually, by determining the solids content of the upper part of a dispersion, the sedimentation /

Aggregation of particles determined. A strong decrease in the solids content indicates the low colloidal stability of the dispersion.

An essential component for the synthesis of nanoscale metal dispersions is the dispersing additive used. This must be present in an amount sufficient to disperse the metal particles, but in a later application should minimize the function of the metals and therefore be present in low concentration as possible. Excessive occupancy of the surface can also lead to an unfavorable influence on the physico-chemical properties of the metal sols.

Metal dispersions are used primarily in microelectronic components as conductors, semiconductors or for shielding electromagnetic fields. The

Metal particles must be applied finely dispersed without agglomeration first, and should form a continuous layer after a hardening process. It is particularly advantageous for this hardening process a) to spend as little energy as possible or b) to reduce the hardening time. This should make it possible to use temperature-sensitive substrates.

This u. a. for security reasons, z. B. by eliminating the flash point, water-dispersible metal dispersions solvent-containing systems preferred. For economic and technical reasons, the use of highly concentrated metal dispersions is sought, as this allows a great deal of freedom for further formulation.

The preparation of aqueous metal dispersions is described in various ways in the literature.

For example, US Pat. No. 2,902,400 (Moudry et al.) Discloses the use of microscopic silver particles obtained by the chemical reduction of silver nitrate

Hydroquinone and tannic acid are obtained as disinfectants. to Stabilization special gelatine products are chosen and in one

discontinuous procedure implemented. A continuous synthesis with clearly defined polymeric dispersing aids has not been described. A separation of unreacted starting materials or formed reaction products was not carried out. The dispersed microparticles obtained at a concentration of 0.6% by weight were diluted to 1: 50,000 with deionized water.

US-2,806,798 describes a process for producing yellow colloidal

Silver brine for photographic applications. As stabilizing agents are described polyethylene glycols or polypropylene glycols or glycerol in connection with polyvinyl alcohol, polyvinyl esters and acetals. Copolymers consisting of (meth) acrylic monomers are not used in the document. To reduce various silver salts in the examples toxic

Hydrazine hydrate described. The purification is carried out by precipitation in acetone and redispersing in water. The silver sol thus obtained is embedded in photosensitive layers. On conductivity of sintered silver particles is not discussed.

In US 3,615,789 colloidal silver is used for color filter systems and photographic layers. As flocculants are sulfonated

Diaminobiphenyl described and as a protective colloid gelatin use.

Both classes of substance contain sulfur and are therefore an additive for the

Preparation of pure silver compounds unsuitable (formation of AgS). The

Preparation of colloidal silver with a final weight fraction of

1, 3 - 4.2% silver is carried out by a batch procedure and involves several complex purification steps. However, there is no reference to the

Temperature dependence of the silver particles.

The synthesis of silver oxide nanoparticles and their conversion to metallic silver is discussed in EP-A-1493780. The conductive composition comprises a particulate silver compound and a binder and optionally

Reducing agent and a binder. Silver oxide, silver carbonate, silver acetate and the like are used as the particulate silver compound. Ethylene glycol, Diethylene glycol, ethylene glycol diacetate and other glycols are considered

Reducing agent used. A fine powder of a thermosetting resin such as a polyvalent styrene resin or polyethylene terephthalate having a

average particle diameter of 20 nm to 5 pm is used as a binder. The particulate silver compound is reduced to elemental silver at temperatures above 50 ° C in the binder, which together

merge. However, EP-A-1493780 does not disclose how highly concentrated aqueous dispersions of silver nanoparticles produce a conductive layer at temperatures below 150 ° C.

Ruy et al., Key Engineering Materials, Vol. 264-268 (2004), pages 141-142 teaches the synthesis of nanoscale silver particles using homopolymeric ammonium salts. Silver nitrate is converted to elemental silver with sodium borohydride or hydrazine. An aqueous, maximum 10% silver dispersion having a particle size <20 nm is obtained. No statements are made regarding the storage stability and the sintering behavior at low temperatures below 130 ° C.

US Pat. No. 8,227,022 describes the preparation of aqueous dispersions of metallic nanoparticles in a two-stage process. For this purpose, in a first substep, a dissolved metal salt is prereduced with a water-soluble polymer and completely reduced by a reducing agent. In a second partial step, the nanoparticles are concentrated and redispersed by a second dispersant. The described preparation process was carried out in small, customary amounts in the laboratory and gives a silver dispersion with max. 18% Ag share. The proportion of dispersant relative to silver was found to be 5.7% at best. The values listed in Table 4 show that even at relatively low levels

Temperatures from 60 ° C, a conductivity is generated. This is disadvantageous because such conditions lead to premature sintering of the metal particles due to the waste heat within the printing process or due to the printing-related heating of the substrate and thus cause the failure of the machines used. In US Pat. No. 8,460,584, a method is described how low molecular weight carboxylic acids (C chain length C4-C20) silver nanoparticles can be prepared. After precipitation of the particles, they can be dispersed in organic solvents (toluene) and oleic acid. An ecologically harmless

Dispersion in water is not described. To determine the electrical conductivity, the product is applied to a glass plate and sintered at a temperature of 210 ° C. The conductivity is 2.3 E04 S / cm

(= 2.3 E06 S / m). A method for producing concentrated nanoscale metal oxide dispersions and their further use in the production of nanoscale metal particles has been described in WO 2007/1 18669. There are metal oxides by means

Reduced formaldehyde to elemental silver. The metal particles are dispersed in the aqueous phase by the addition of a dispersing aid. Through the use of the dispersing aid, the metal particulate sols and their oxidic precursors have a high colloid-chemical stability.

In one embodiment of the document WO 2007/1 18669, dispersing aids are selected from the group comprising alkoxylates, alkylolamides, esters,

Amine oxides, alkylpolyglycosides, alkylphenols, arylalkylphenols, water-soluble homopolymers, random copolymers, block copolymers, graft polymers, polyethylene oxides, polyvinyl alcohols, copolymers of polyvinyl alcohols and polyvinyl acetates, polyvinylpyrrolidones, cellulose, starch, gelatin,

Gelatin derivatives, amino acid polymers, polylysine, polyaspartic acid,

Polyacrylates, polyethylene sulfonates, polystyrenesulfonates, polymethacrylates,

Condensation products of aromatic sulfonic acids with formaldehyde,

Naphthalenesulfonates, ligninsulfonates, copolymers of acrylic monomers, polyethyleneimines, polyvinylamines, polyallylamines, poly (2-vinylpyridines) and / or polydiallyldimethylammonium chloride. The document does not specify the stability and conductivity of the brine produced.

WO-2012/055758 discloses a method with a foreign element doped metal particles to represent the electrical conductivity at low To reach sintering temperatures. In an example according to the invention, an Ag sol was prepared which had a conductivity of 4.4 E + 06 S / m after one hour at 140 ° C. A comparative sample without RuO2 doping gave a specific conductivity of 1 S / m after one hour at 140.

The application US-2006/044384 describes the use of random and terpolymer of methacrylic acid and polyethylene glycol dimethacrylate (PEGMA). Examples use hydroxyl-terminated PEGMA having a molecular weight of 256 g / mol or 360 g / mol. It is stated in paragraph [0009] that the non-ionic fraction should have a chain length below 1000 g / mol. The reduction to elemental silver occurs with toxic hydrazine. Ag sols having a concentration of up to 30% by weight are prepared. In order to ensure a sufficient stability of the particles are 10 - 100 wt .-%

(based on silver), dispersants necessary. An electrical conductivity was detected, but neither the parameters (layer thickness,

Temperature) still one unit revealed. The storage stability of the produced particles has not been investigated.

All of the methods described for the production of nano- and submicron-scale metal particles have significant disadvantages. So z. B. the process described not industrially represent or the particles produced have a very high loading with dispersant. If the particles are to produce an electrical conductivity, then the sintering is only at relatively high

Temperatures of at least 140 ° C instead and therefore is not suitable for use on temperature-sensitive polymeric substrates.

Object of the following invention was thus to find a dispersant, which on the one hand the industrial production highly concentrated

Metal dispersions allows and ensures high colloid-chemical stability even when stored up to 60 ° C. The dispersions thus prepared should after a coating process and a thermal or

photonic treatment become electrically conductive even at relatively low temperatures from 90 ° C and therefore for temperature-sensitive plastic substrates be applicable. Another goal is to generate better conductivity than the prior art at the same sintering temperatures and times.

As has surprisingly been found, copolymers based on mixed alkoxylated (meth) acrylic acid derivatives and acrylic monomers are very suitable as dispersants for the preparation of nanoscale

Metal particles. In comparison to known, homogeneously alkoxylated

Methacrylic acid derivatives, the aqueous nanoscale metal dispersions prepared with the copolymer according to the invention have a significantly better storage stability at room temperature, in particular up to 60 ° C. At elevated temperatures, however, surprisingly, a reversal of the stability can be determined, which means that the particles produced with the polymers according to the invention sinter already from a temperature of 90 ° C. So z. B. good conductivity values even at low sintering temperatures of at least 1, 8 E06 S / m, in particular of 2.0 E06 S / m at 90 ° C, at least 2.9 E06 S / m, in particular 3.1 E06 S / m at 1 10 ° C and at least 5.2 E06 S / m, in particular 5.4 at 130 ° C, can be achieved. The

Therefore, metal dispersions according to the invention also allow it

to use temperature-sensitive substrates as substrate and still achieve good conductivities, which was previously not possible with the known metal dispersions.

This allows the use of temperature-sensitive substrates. Likewise, an improved electrical conductivity can be achieved while reducing the time load.

The present invention solves the problem and therefore relates to metal dispersions containing as dispersants copolymers containing 1 - 99 wt .-%

Structural units of the formula (1) wherein

R is hydrogen or O-Ce alkyl

A C2-C4 alkylene group and,

B is C 2 -C 4 alkylene group, with the proviso that A is different from B and m, n independently of one another are an integer from 1 to 200, and from 1 to 99% by weight of structural units of the formula (2)

is an aromatic or aliphatic radical having 1 to 30 carbon atoms, optionally one or more, for. B. 1, 2, or 3

Contains heteroatoms N, O and S,

is H or (C 1 -C ₄ ) -alkyl,

is H or (Ci-C-4) -alkyl and

is H or (Ci-C ₄ ) -alkyl. The embodiments of the invention described below relate to the use:

R is in a preferred embodiment of the invention for

Hydrogen or methyl.

A and B represent C2-C4 alkylene groups with the proviso that A is not equal to B. That is, the structural units of formula (1) can be up to 200

C2-C4 alkoxy units may be alkoxylated, either being to a blockwise alkoxylation with at least two

Ethylene oxide, propylene oxide or butylene oxide or a (random)

Mischalkoxylierung with at least two of ethylene oxide, propylene oxide or butylene oxide can act.

Preferably, A and B are an ethylene or propylene group. A is preferably a propylene group and B is an ethylene group. Specifically, A is a propylene group and B is an ethylene group, provided that m = 2 to 7 and n = 50 to 200, preferably m = 2 to 6 and n = 50 to 200, very preferably m = 3 to 6 and n = 50 to 200.

The macromonomers based on structural units of the formula (1) are accessible by the polymerization of alkoxylated acrylic or methacrylic acid derivatives (hereinafter the term acrylic acid also refers to the methacrylic acid). These are by alkoxylation of acrylic acid or 2-alkylacrylic acid or

Acrylic acid monoesters of ethylene glycol, propylene glycol or butylene glycol (2-hydroxyethyl acrylate, 2-hydroxypropyl acrylate or 2-hydroxybutyl acrylate) or 2-alkylacrylic acid monoesters of ethylene glycol, propylene glycol or

Butylene glycol (2-hydroxyethyl-2-alkyl acrylate, 2-hydroxypropyl-2-alkyl acrylate or 2-hydroxybutyl-2-alkyl acrylate) available.

Particularly preferred are the alkoxylated acrylic acid derivatives

DMC-catalyzed alkoxylation of 2-hydroxypropyl acrylate or 2-hydroxypropyl-2-alkyl acrylate, especially by DMC-catalyzed alkoxylation of 2-hydroxypropyl-2-methacrylate. In contrast to traditional alkaline catalyzed alkoxylation, DMC catalysis allows a highly targeted synthesis of monomers with well-defined properties while avoiding

unwanted by-products. DE-102006049804 and US-6034208 teach the benefits of DMC catalysis.

The following list contains preferred synthesis examples analogously to the above synthesis instructions: The composition of the structural units of the formula (1) is preferably at least one of the following polyglycols: polyglycol 1 polyalkylene glycol methacrylic acid ester (formula (1), m = 2, n = 12-13; (AO) corresponds to [CH ₂ CH (CH ₂ ₃₎ O)]; (BO) corresponds

(CH2CH2O)); Molar mass approx. 750 g / mol

Polyglycol 2 Polyalkylene glycol methacrylic acid ester (Formula (1), m = 2, n = 17-19; (AO) corresponds to [CH ₂ CH (CH ₃ ) O)]; (BO) corresponds to (CH 2 CH 2 O)); Molecular weight about 1000 g / mol

Polyglycol 3 Polyalkylenglykolmethacrylsäureester (formula (1), m = 5, n = 38-40; (AO) corresponding to [CH ₂ CH (CH ₃₎ O)]; (BO) corresponds

(CH2CH2O)); Molecular weight about 2000 g / mol

Polyglycol 4 Polyalkylene glycol methacrylic acid ester (Formula (1), m = 5, n = 95-105; (AO) corresponds to [CH ₂ CH (CH ₃ ) O)]; (BO) corresponds

(CH2CH2O)); Molecular weight about 5000 g / mol

Polyglycol 5 Polyalkylene glycol methacrylic acid ester (Formula (1), m = 5, n = 190-200; (AO) corresponds to [CH ₂ CH (CH ₃ ) O) j; (BO) corresponds to (CH 2 CH 2 O)); Molecular weight about 12000 g / mol

Suitable structural units of the formula (2) are preferably those selected from styrenesulfonic acid, acrylamidomethylpropanesulfonic acid (AMPS), vinylsulfonic acid, vinylphosphonic acid, allylsulfonic acid, methallylsulfonic acid, acrylic acid,

Methacrylic acid and maleic acid or its anhydride, and the salts of the aforementioned acids with mono- and divalent counterions derived, and 2-vinylpyridine, 4-vinylpyridine, vinylimidazole, vinyl acetate,

Methacrylic acid glycidyl esters, acrylonitrile, tetrafluoroethylene and DADMAC, deduce. Further examples are N-vinylformamide, N-vinylmethylformamide,

N-vinylmethylacetamide, N-vinylacetamide, N-vinylpyrrolidone (NVP), 5-methyl-N-vinyipyrrolidone, N-vinylvalerolactam and N-vinylcaprolactam. In a preferred embodiment, the structural units of the formula (2) derive from N-vinylimidazole, N-vinylpyrrolidone, N-vinylcaprolactam, acrylic acid and

From methacrylic acid. The polymers to be used according to the invention contain, for example, from 99 to 70, preferably from 95 to 75, in particular from 90 to 80,% by weight of structural units of the formula (1).

In a preferred embodiment, the structural units of the formula (1) and the structural units of the formula (2) add up to 100%.

The preparation of the polymers to be used according to the invention is carried out by free radical polymerization of the monomers using a

suitable radical starter at temperatures between 50 and 150 ° C. The molecular weight of these polymers can range from 6,000 to

1 x 10 ⁶ g / mol, preferably 15,000 to 800,000, but most preferred are molecular weights between 20,000 and 600,000 g / mol.

Suitable alcoholic solvents are water-soluble mono- or

Dialcohols, such as. As propanol, butanol, ethylene glycol and ethoxylated

Monoalcohols such as butylglycol, isobutylglycol and butyldiglycol. But it can also be used alone as a solvent water. They form after the

Polymerization generally clear solutions.

The dispersant solutions thus prepared may contain other substances, such. Biocides, UV stabilizers, anti-oxidants, metal deactivators,

IR absorbers, flame retardants and the like in an amount of

0.01-1.0% by weight, preferably 0.01-0.5% by weight and most preferably

0.1-0.25% by weight.

In a preferred embodiment, the nanoscale metal particles are continuously produced in a microreaction system analogously to the document WO 2007/1 18669, Section [0027] to [0056]. The resulting metal particle sols were purified by membrane filtration and concentrated to a solids content of silver particles of 50-80 wt .-%, preferably 51-79 wt .-% and particularly preferably 52-78 wt .-%. The particle size of the silver particles is preferably in at least one dimension between 5 and 100 nm. The dispersant content is 1-9 wt .-%, preferably 2-8 wt .-% and particularly preferably 3-7 wt .-%. A TEM image of a sample prepared according to the invention of silver nanoparticles and the corresponding

Particle size distribution by volume is shown in Figures (1) and (2).

Examples: The synthesis of the copolymers is carried out as follows: in a flask with

Stirrer, reflux condenser, internal thermometer and nitrogen inlet, the polyglycol of the formula (1) and the acrylic monomer of the formula (2) and a molecular weight regulator are presented in solvent under nitrogen in the parts by weight given in the table below. The temperature is then brought to 80 ° C. with stirring and a solution of the initiator is metered in within one hour. It is stirred for two more hours at this temperature. Subsequently, further additives can be added. The table below summarizes the composition of the copolymers

Table 1: Copolymers of the invention

Example 1 2 3 4 5 6 7 8 9 10

Polyglycol 1 (M _w = 750 g / mol) 67.7 67.7 62.5 59.8

Polyglycol _(w = 1000 M) 62.4 62.4 57.7 59.7 2 ω

e

o Polyglycol 3 (M _w = 2000) 67.7 67.7 cz

O

Polyglycol 4 (M _w = 5000)

Polyglycol 5 (M _w = 12000)

Methacrylic acid 1, 9, 3.8, 6.0, 3.9, 3.9, 1, 9

Acrylic acid 4.0 4.1 6.0 10

Vinylimidazole 1, 9 2.0 5.9

CM

Vinyl pyrrolidone 2.0 1, 9 ω

e

o Vinylcaprolactam 4.0

f 4.1

O

Έ benzyl methacrylate 3.9

isobornyl

2-ethylhexyl methacrylate 2.0

phenoxyethyl

Initiator sodium peroxodisulfate 3.1 2.2 2.3 2.3 2.3 2.3 2.6 2.6 2.2 2.2

Regulator mercaptopropionic acid 0.4 0.4 0.4 0.4 0.4 0.4 0.5 0.5 0.4 0.4

Water 25.0 26.8 26.9 25.8

solvent

Butyl glycol 24.9 26.85 26.9 29.4 29.4 25.8

Additive 1, 2-Benzisothiazol-3 (2H) -one 0.1 0.15

Table 2: Copolymers of the invention

Example 1 1 12 13 14 15 16 17 18 19 20

Polyglycol 1 (M _w = 750 g / mol)

Polyglycol 2 (M _w = 1000) 4.0

Monomer 1 Polyglycol 3 (M _w = 2000) 62.7 60.2

Polyglycol 4 (M "= 5000) 65.8 67.7 63.7 63.7

Polyglycol 5 (M _w = 12,000) 67.7 62.4 62.6 62.5

Methacrylic acid 8 2.9 3.9 3.9 8.0 4.0

Acrylic acid 2.9 2.0 4.9 4.0

Vinylimidazole 2.1 3.9

Vinyl pyrrolidone 1, 9

Monomer 2 vinylcaprolactam 4.0

Benzyl methacrylate 4.0

Isobornyl methacrylate 4.0

2-ethylhexyl methacrylate 6

Phenoxyethyl methacrylate 2.1

Initiator Sodium peroxodisulfate 2.3 2.4 2.2 2.2 2.2 2.2 2.2 2.3 2.3 2.3

Regulator mercaptopropionic acid 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4 0.4

Water 26.6 25.9 25.9 23.6 26.7

solvent

Butyl glycol 26.9 25.8 24.8 26.9 26.8

Additive 1, 2-Benzisothiazol-3 (2H) -one 0.1 0.1

Production of metal nanoparticles:

The nanoscale metal particles were continuously produced in a microreaction system analogous to document EP-2010314, section [0027] to [0056]. The resulting metal particle sols were purified by membrane filtration and concentrated to a metal content of 50-80% by weight. The dispersant content could be determined to be 1-9% by weight.

Table 3: Silver content and dispersant content

Example based silver content content of water content on copolymer dispersant

and additive

[Wt%] [wt%] [wt%]

1 57.8 3.9 38.3

2 58.1 4.0 37.9

3 56.2 3.1 40.7

4 56.4 4.8 38.3

5 53.2 3.2 43.6

6 54.8 3.3 41, 9

7 54.1 2.2 43.7

8 58.2 3.0 38.8

9 57.8 3.4 38.8

10 57.0 3.3 39.7

1 1 78.9 6.8 14.3

12 73.6 6.3 20.1

13 55.3 3.1 41, 6

14 58.7 3.8 37.5

15 54.1 5.1 40.8

16 59.8 4.0 36.2

17 67.5 5.1 27.4

18 68.4 5.6 26.0

19 58.2 5.0 36.8 20 56.8 3.8 39.4

Comparison 1 16,1 12.5 71, 4

(US 2006044384 "A")

Comparison 2 19.2 1 1, 5 69.3

(US 2006044384 "G")

Comparison 3 8 2.3 89.7

(WO-2012/055758)

Comparison 4 3, 1 18.3 78.6

(US 8227022)

For comparison, metal nanoparticles were prepared analogously to the specifications US-20060044382 (Lexmark, Example A [0019] and Example G [0023]), WO-2012/055758 (Bayer Technology Services / BTS, Example 1) and US-8227022, and US Pat Comparative Example 1, 2, 3 and 4 attached.

test results

The silver sols obtained were stored at room temperature and the solid (= sum of silver and dispersant content) of the dispersion was determined at intervals of 4, 8 and 16 weeks without stirring the sample. A decrease of the solid indicates sedimentation of the silver particles and thus a lower stability of the dispersion.

Table 4: Shelf life at room temperature

Ag-sol based solids after 4 solids after 8 solids after 16 on copolymer weeks Storage weeks Storage weeks Storage

[Wt%] [wt%] [wt%]

1 61, 5 61.3 61, 6

2 62.0 62.3 61, 8

3 59.3 59.0 58.9

4 61.0 61, 2 61.0

5 56.5 56.3 56.2

6 57.8 57.9 57.8

7 56.3 56.3 56.1 8 61.0 61, 4 61.0

9 60,8 61, 0 61, 2

10 60.5 60.2 59.8

1 1 78.6 78.7 78.5

12 73.5 73.7 73.5

13 58.4 58, 1 58.0

14 62.3 62.6 62.6

15 59.3 59.3 59.1

16 63.5 63.4 63.3

17 67.2 67.1 66.8

18 68.4 68.2 67.9

19 63.5 63.3 63.2

20 60.1 60, 1 59.8

Comparison 1 25.2 20.3 12.8 (US-2006044384 "A")

Comparison 2 27.3 22.1 13, 1 (US-2006044384 "G")

Comparison 3

7.8 6.5 4, 1 (WO-2012055758 "1")

Comparison 4

20.2 19.9 19.3 (US-8227022)

As can be seen from the above table, all based on the

Polymers of the invention based on a significantly higher stability at room temperature than the silver brine on the prior art (Comparative 1-4).

For electrical testing, the obtained metal sols were applied by means of spin-coating to a 18 × 18 mm glass plate in a layer thickness of between 0.1 and 10 μm, preferably between 0.5 and 5 μm. The glass plate was then thermally sintered at a defined temperature for 60 minutes and the 4-point measuring method, the surface resistance in

[Ohms / square] measured. After determination of the layer thickness, the specific conductivity could be determined in [S / m]. Table 5: Specific Conductivity

Ag-Sol based Conductivity by Conductivity by Conductivity after on Copolymer Sintering at 90 'C Sintering by 1 10 Sintering by 130

[E06 S / m] C C

[E06 S / m] [E06 S / m]

1 3.5 3.9 5.2

2 3.8 4.1 5.3

3 3.7 4.3 5.6

4 2.5 2.9 6.0

5 2.7 4.0 5.8

6 2.3 4.2 5.5

7 1, 8 4,2 5,7

8 2.5 4.4 5.6

9 3.8 6.1 6.3

10 4.2 5.9 6.9

1 1 6.4 8.3 9.2

12 6.1 8.2 9.0

13 3.7 4.2 7.0

14 5.1 6.9 7.8

15 5.3 6.5 8.0

16 4.9 6, 1 7.4

17 5,7 7.6 8, 1

18 4.4 7.7 8.0

19 4.3 7.3 7.4

20 4.5 6.9 8.0

Comparison 1 0 0 0 (US-2006044384

"A")

Comparison 2 0 0 0 (US-2006044384

"G") Comparison 3

(WO 2012055758 0 0 4.4 (140 ° C)

"1 ")

Comparison 4

2.0 (100 ° C) k. A. 2.6 (150 ° C) (US 8227022)

Comparison 5

k. A. k. A. 2.3 (210 ° C)

(Xerox)

As can be seen from the table above, all those with the

According to polymers of the invention produced after thermal sintering, the electrical conductivity of the comparative products both with the absolute value and with the beginning of the sintering temperature. This means a lower energy input to achieve comparable electrical conductivity end product. The range of thermosensitive substrates which can be used as printing material is thereby increased.

Claims

claims

1 . Metal dispersions containing 50 to 80 wt.% Of silver nanoparticles, 15 to 45 wt.% Of water and a dispersing agent, wherein the dispersing agent

Contains copolymers containing 1-99 wt .-% of structural units of the formula (1)

wherein

R is hydrogen or Ci-Ce alkyl

A C2-C4 alkylene group and,

B is C2-C4 alkylene group, with the proviso that A is different from B and m, n are independently an integer from 1 to 200, as well as

1 to 99% by weight of structural units of the formula (2)

wherein

Xa is an aromatic or aliphatic radical having 1 to 30 carbon atoms, optionally one or more, for. B. 1, 2, or 3

Contains heteroatoms N, O and S,

Za is H or (C 1 -C ₄ ) -alkyl,

For example, H or (Ci-C4) alkyl and

Z _{c is} H or (Ci-C ₄ ) -alkyl.

2. Metal dispersions according to claim 1, characterized in that A and / or B is an ethylene or propylene group or A is a propylene group and B is an ethylene group or A is a propylene group and B is an ethylene group.

3. Metal dispersions according to claim 1 and / or 2, characterized in that m = 2 to 7 and n = 50 to 200 are.

4. metal dispersions at least one of the preceding claims, characterized in that water-soluble mono- or dialcohols or ethoxylated monoalcohols are included as a further solvent.

5. Metal dispersions according to one or more of claims 1 to 4, characterized in that it is in the composition of

Structural units of the formula (1) is at least one of the following polyglycols:

Polyglycol 1 Polyalkylene glycol methacrylic acid ester (Formula (1), m = 2, n = 12-13; (AO) corresponds to [CH ₂ CH (CH ₃ ) O)]; (BO) corresponds to (CH 2 CH 2 O)); Molar mass approx. 750 g / mol

Polyglycol 3 Polyalkylene glycol methacrylic acid ester (Formula (1), m = 5, n = 38-40; (AO) corresponds to [CH ₂ CH (CH ₃ ) O)]; (BO) corresponds to (CH 2 CH 2 O)); Molecular weight about 2000 g / mol

Polyglycol Polyalkylenglykolmethacrylsäureester 4 (formula (1), m = 5, n = 95-105; (AO) corresponding to [CH ₂ CH (CH ₃₎ O)]; (BO) corresponds to (CH 2 CH 2 O)); Molecular weight about 5000 g / mol

6. Metal dispersions according to one or more of claims 1 to 5, characterized in that the structural units of the formula (2) of N-vinylimidazole, N-vinylpyrrolidone, N-vinylcaprolactam, acrylic acid or

Derive methacrylic acid.

7. Metal dispersion according to one or more of claims 1 to 6, characterized in that it contains 1-9 wt .-% of the dispersant.

8. Metal dispersion according to one or more of claims 1 to 7, characterized in that these further additives in an amount of 0.1 to

1, 0 wt .-% included.

9. Metal dispersion according to one or more of claims 1 to 8, characterized in that the particle size of the silver particles in at least one dimension is between 5 and 100 nm.

10. Metal dispersions according to one or more of claims 1 to 9, characterized in that by sintering at temperatures of 90 ° C.

Conductivity values of at least 1, 8 E06 S / m can be achieved.

1 1. Use of copolymers containing 1-99% by weight of structural units of the formula (1)

R

"" (1)

O

V - 0) _m - (B - O) _n - H wherein

R is hydrogen or Ci-Ce alkyl

A C2-C4 alkylene group and,

B is C2-C4 alkylene group, with the proviso that A is different from B and m, n independently of one another denote an integer from 1 to 200, and also from 1 to 99% by weight of structural units of the formula (2)

wherein

Xa is an aromatic or aliphatic radical having 1 to 30 carbon atoms, optionally one or more, for. B. 1, 2, or 3 heteroatoms contains N, O and S,

Za is H or (C 1 -C ₄ ) -alkyl,

For example, H or (Ci-C-4) -alkyl and

Z _{c is} H or (Ci-C ₄ ) -alkyl

as a dispersing agent for the stabilization of metal dispersions.

12. Use of the metal dispersion according to one or more of claims 1 to 10 for the production of ink compositions, paints, coatings or graphic printed products.

13. Use of the metal dispersion according to one or more of claims 1 to 10 for the production of electrically conductive coatings