SILVER PASTE AND COATINGS PRODUCED THEREFROM

Abstract

The present invention relates to an oxidation-stable silver paste comprising silver nanoparticles, and to the use of a paste of this type for the production of decoration elements having a metallic luster on articles having an outer silicate surface, such as porcelain, ceramic, bone china, glass or enamel, to metallic coatings on such substrates and to a process for the production of coatings of this type.

Claims

1. A silver paste comprising the following components: A) 10 to 40% by weight of nanoparticles comprising silver or a silver-containing alloy, where the nanoparticles have a D.sub.50 value, measured using the volume-based laser diffraction process, of 30 300 nm, B) 10 to 30% by weight of at least one organic compound containing silicon, C) 30 to 70% by weight of a solvent or solvent mixture, D) 15 to 35% by weight of at least one natural resin, E) 0 to 30% by weight of at least one organic metal, alkaline-earth metal or alkali metal compound, where the chemical element is selected from the group Ag, Au, Bi, Ca, Co, Cr, Cu, Fe, Ir, K, Mg, Mn, Na, Nb, Ni, Os, Pd, Pt, Os, Rh, Ru, Sn, Ti, W, V, Zn, Zr, F) 0 to 10% by weight of one or more synthetic additives, and G) 0 to 10% by weight of at least one synthetic resin, where the percent data are based on the total weight of the silver paste and add up to 100%.

2. The silver paste according to claim 1, wherein the silver nanoparticles employed are monodisperse.

3. The silver paste according to claim 1, wherein the silver nanoparticles employed have been stabilized.

4. The silver paste according to claim 1, wherein the organic compound of component B) is selected from the group polysilazanes, polysiloxanes, silicones, silicone-modified alkyd resins, silicone polyester resins, polysilsesquioxanes, polysilanes, polysilanols or derivatives thereof and mixtures of the said organic compounds and polymers.

5. The silver paste according to claim 1, where the solvent is selected from the group alcohols, aromatic solvents, ketones, esters, ethers, ether alcohols, saturated and unsaturated aliphatic hydrocarbons or amides or mixtures thereof.

6. The silver paste according to claim 1, where the natural resin is selected from the group non-hydrogenated, partially hydrogenated and/or fully hydrogenated resins based on colophony, non-hydrogenated, partially hydrogenated and/or fully hydrogenated resins based on colophony esters, non-hydrogenated, partially hydrogenated and/or fully hydrogenated resins based on crude tall oil, non-hydrogenated, partially hydrogenated and/or fully hydrogenated resins based on crude tall oil esters, terpene-based resins and/or the respective derivatives thereof and mixtures of the said resins.

7. The silver paste according to claim 1, wherein the metal compound of component E) is selected from the group acetates, resinates, sulforesinates, mercaptides, thiolates, carboxylates, ethylhexanoates and alcoholates.

8. The silver paste according to claim 1, wherein the additive of component F) is selected from the group thixotropic agents, flow-control agents, dispersants, rheology modifiers, antifoams, surfactants, fillers and dyes.

9. The silver paste according to claim 1, wherein component G) is a synthetic resin selected from the group phenolic, amino, epoxy, polyester, polyacrylate, alkyd, polyurethane, polyamide, vinyl and furan resins.

10. The silver paste according to claim 1, wherein said nanoparticles of component A) have a D.sub.50 value of 30-200 nm.

11. The silver paste according to claim 1, wherein said nanoparticles of component A) have a D.sub.50 value of 50-100 nm.

12. The silver paste according to claim 1, wherein the proportion of component A) in the silver paste is 10-30% by weight.

13. The silver paste according to claim 1, wherein the proportion of component A) in the silver paste is 15-25% by weight.

14. The silver paste according to claim 1, wherein proportion of component B) in the silver paste is 12-28% by weight.

15. The silver paste according to claim 1, wherein proportion of component B) in the silver paste is 14-25% by weight.

16. A process for the preparation of a silver paste according to claim 1, comprising intimately mixing all components A) to D) and optiocally components E), F) and/or G) with one another, giving a ready-to-use silver paste.

17. The process according to claim 16, wherein the mixing is carried out using a rotor-stator homogenizer, a triple-roll mill or a speed mixer.

18. A method of producing a coating, decoration element, or inscription on an article having a porcelain, bone china, ceramic, glass or enamel surface comprising applying to said surface a silver paste according to claim 1.

19. The method according to claim 18, wherein, after application of the silver paste to the surface, the silver paste is subsequently treated at a temperature of 400-900° C.

20. The process according to claim 18, the paste is applied to the surface by curtain coating, roller coating, spin coating, impregnation, pouring, dripping, squirting, spraying, knife coating, ink-jet printing, screen printing, gravure printing, offset printing, pad printing, pen painting, or brush painting.

Description

EXAMPLES

Example 1

[0097] A resin solution prepared from 50% of Dymerex™ (colophony resin from Eastman) and 50% of 1-methoxy-2-propanol is employed as binder. 3 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in ethanol, solids content 45%, NanoComposix), 2 g of a polymer mixture (Dowsil™ Fluid 593: polydimethylsiloxane/silicone resin mixture, Dow Chemicals), 0.1 g of platinum resinate MR7801-P (Alfa Chemistry), 0.2 g of bismuth(III) 2-ethylhexanoate (ABCR) and 0.7 g of 1-methoxy-2-propanol are subsequently added. The mixture formed is stirred until homogeneous.

[0098] The silver paste obtained in this way, which is particularly suitable for brush application, is then applied to a glass by brushing. After drying, the decorated glass is fired at 560° C. for 30 minutes. In this way, a particularly lustrous, dark platinum-like decoration is obtained on the glass surface.

Example 2

[0099] A resin solution, prepared from 70% of Dymerex™ (colophony resin from Eastman) and 30% of Dowanol DPM (dipropylene glycol monomethyl ether), is employed as binder. 4 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in ethanol, solids content 45%, NanoSaar AG), 1 g of a polymer mixture (Dowsil™ Fluid 593: polydimethylsiloxane/silicone resin mixture, Dow Chemicals), 0.1 g of platinum resinate MR7801-P (Alfa Chemistry), 0.2 g of bismuth(III) 2-ethylhexanoate (ABCR) and 0.7 g of 1-methoxy-2-propanol are subsequently added. The mixture formed is stirred until homogeneous.

[0100] The viscous silver paste obtained in this way, which is suitable for printing, is then applied to a glass. After drying, the decorated glass is fired at 560° C. for 30 minutes. In this way, a lustrous, platinum-like decoration is obtained on the glass surface.

Example 3

[0101] A resin solution, prepared from 60% of Poly-Pale™ (partially dimerized colophony resin from Eastman) and 40% of terpineol, is employed as binder. 4 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in DPM, solids content 45%, DOWA Electronics Materials Co., Ltd.), 1 g of a polymer mixture (DX175 from Shin-Etsu), 0.1 g of platinum resinate (Fuji), 0.2 g of bismuth(III) 2-ethylhexanoate and 0.7 g of 1-methoxy-2-propanol are subsequently added. The mixture formed is stirred until homogeneous.

[0102] The metal paste obtained is then applied to a glass by means of screen printing. After drying, the decorated glass is fired at 560° C. for 30 minutes. In this way, a silk, platinum-like decoration is obtained.

Example 4

[0103] A resin solution, prepared from 50% of Poly-Pale™ (partially dimerized colophony resin, Eastman) and 50% of terpineol, is employed as binder. 4 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in DPM, solids content 45%, DOWA Electronics Materials Co., Ltd.), 2 g of a polymer mixture RHODORSIL HARZ 6405 X (methylphenyl-silicone resin from Bluestar Silicones), 0.1 g of palladium resinate (Alfa Chemistry), 0.2 g of bismuth(III) 2-ethylhexanoate and 0.7 g of 1-methoxy-2-propanol are subsequently added. The mixture formed is stirred until homogeneous. The silver paste formed, which is particularly suitable for screen printing, is then applied to a glass by means of screen printing. After drying, the decorated glass is fired at 560° C. for 30 minutes. In this way, a lustrous, whitegold-like decoration is obtained.

Example 5

[0104] A resin solution, prepared from 50% of balsam resin (TER Chemicals) and 50% of 1-methoxy-2-propanol, is employed as binder. 4 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in terpineol, solids content 50%, PV Nanocell), 2 g of a polymer mixture (Dowsil™ Fluid 593: polydimethylsiloxane/silicone resin mixture (Dow Chemicals), 0.1 g of platinum resinate MR7801-P (BOC Science) are subsequently added. The mixture formed is stirred until homogeneous.

[0105] The paste formed, which is particularly suitable for screen printing, can then be applied to a glass. After drying, the decorated glass is fired at 600° C. for 30 minutes. In this way, a particularly lustrous, very bright platinum-like decoration is obtained.

Example 6

[0106] A resin solution, prepared from 50% of gum rosin (Sigma-Aldrich) and 50% of 1-methoxy-2-propanol, is employed as binder. 4 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in terpineol, solids content 50%, DOWA Electronics Materials Co., Ltd.), 2 g of a polymer mixture (Dowsil™ 2502, Cetyl Dimethicone, Dow Chemicals), 0.1 g of palladium resinate (Daiken) are subsequently added. The mixture formed is stirred until homogeneous.

[0107] The paste formed can then be applied to a glass by means of screen printing, spraying or brushing. After drying, the decorated glass is fired at 560° C. for 30 minutes. In this way, a lustrous, dark white-gold-like decoration is obtained.

Example 7

[0108] A resin solution, prepared from 60% of balsam resin (TER Chemicals) and 40% of 1-methoxy-2-propanol, is employed as binder. 4 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in terpineol, solids content 50%, PV Nanocell), 2 g of a polymer mixture (Dow-Sil 593), 0.1 g Au resinate (Hereaus) are subsequently added. The mixture formed is stirred until homogeneous.

[0109] The silver paste formed is then applied to a glass by means of screen printing, spraying or brushing. After drying, the decorated glass is fired at 560° C. for 30 minutes. In this way, a silk, white-gold-like decoration is obtained.

Example 8

[0110] A resin solution, prepared from 50% of gum rosin (Sigma-Aldrich) and 50% of terpineol, is employed as binder.

[0111] 4 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in TPM, solids content 50%, Seashell Technology, LLC), 2 g of a polymer mixture Silres® HK46 (methylsilicone resin, Wacker), 0.1 g of platinum resinate MR7801-P (Alfa Chemistry) are subsequently added. The mixture formed is stirred until homogeneous.

[0112] The silver paste formed, which is particularly suitable for screen printing, is then applied to a glass by means of screen printing, spraying or brushing. After drying, the decorated glass is fired at 620° C. for 30 minutes. In this way, a lustrous, extremely resistant platinum-like decoration is obtained.

Example 9

[0113] A resin solution, prepared from 50% of BREMAR 6091 (Robert Kraemer GmbH) and 50% of 1-methoxy-2-propanol, is employed as binder. 4 g of the above solution are initially introduced. 4 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in terpineol, solids content 50%, PV Nanocell), 3 g of a polymer mixture Durazane 1066 (silicone resin, Merck KGaA), 0.1 g of platinum resinate MR7801-P (Alfa Chemistry) are subsequently added. The mixture formed is stirred until homogeneous. The paste formed is then applied to a glass by means of screen printing, spraying or brushing. After drying, the decorated glass is fired at 560° C. for 30 minutes. In this way, a particularly scratch-resistant, lustrous, platinum-like decoration is obtained.

[0114] The decorations of Examples 1-9 are H2S-resistant, oxidation-stable and exhibit no greying in accordance with the ISO 4538-1978 (E) standard. Depending on the atmosphere, the decoration is then stable for many years.

Example 10

[0115] 40 g of cyclohexanone are heated at a temperature of 120° C. 20 g of SYNOLAC® 3132×75 from Arkema and 40 g of Rosin WW (TER Chemicals) are added with stirring until everything has dissolved. A clear brown solution is visible after cooling to room temperature. 30 g of this resin solution are removed and mixed with 10 g of Durazen 1800 (polysilazane from Merck), 1 g of bismuth(III) 2-ethylhexanoate, 0.5 g of 10% Calcium Cem-All (Borchers), 40 g of Ag nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in TPM (50% solids content in tripropylene glycol monomethyl ether) and 18.5 g of resin solution from Example 2. After brief stirring, this mixture is homogenized in a triple-roll mill. The printing paste prepared in this way is printed directly onto transfer paper with the aid of a screen-printing process (150/31 polyester) and later overprinted with L406 lacquer from Ferro and, after drying, applied to a glass and fired at a temperature of 580° C. A platinum-like hue is obtained.

Example 11

[0116] 21 g of Dowanol DPM (dipropylene glycol monomethyl ether) and 10 g of terpineol are slowly added with stirring to 12 g of 3-(trimethoxysilyl)propyl methacrylate from Aldrich.

[0117] The mixture is heated to 120° C. with stirring, and 50 g of Poly-Pale Rosin (Eastman) are then added until all resin parts have dissolved. 3 g of gold resinate MR 7901-P (Fuji) and 3 g of palladium resinate MR 4601-P (Fuji) are added. The entire solution is stirred for 3 hours until all the resinates have dissolved. 1 g of cobalt(II) 2-ethylhexanoate solution (“12% Co HexCem” from Borchers) is then added.

[0118] This mixture is homogenized in a roll mill. This paste is printed onto transfer paper with the aid of a screen-printing process (150/31 polyester) and allowed to dry in air. It is then overprinted with a lacquer, such as, for example, L406 from Ferro. After application to a glass, the coating is fired at a temperature of 560° C. A platinum hue is obtained.

Example 12

[0119] A resin solution prepared from 60% of gum rosin (Sigma-Aldrich) and 40% of terpineol is employed as binder. 4 g of the above solution are initially introduced. 3.5 g of a paste of silver nanoparticles (D.sub.50=70 nm, D.sub.90=115 nm, in terpineol, solids content 50%, PV Nanocell), 2 g of a polymer mixture (Dowsil™ Fluid 593: polydimethylsiloxane/silicone resin mixture (Dow Chemicals), 0.2 g of palladium resinate solution (MR4601-P, Wako Chemicals, w=15% in terpineol) and 0.25 g of a 50% solution of copper resinate (Kremer Pigmente) in terpineol are subsequently added. The mixture formed is stirred until homogeneous.

[0120] The silver paste obtained, which is particularly suitable for screen printing, is then applied to a glass by means of screen printing, spraying or brushing. After drying, the decorated glass is fired at 620° C. for 30 minutes. In this way, a lustrous, resistant, very bright, platinum-like decoration is obtained.