Process for producing a shiny laminate structure at low temperatures

Abstract

Process for producing a layer structure, which comprises the steps: E1. provision of a composition comprising i. gold (Au) particles in an amount in the range from 0.1 to 50% by weight; ii. a balance to 100% by weight of a polar, protic organic solvent; iii. less than 5% by weight of water, where the % by weight, in each case based on the total mass of the composition, add up to 100% by weight; E2. application of the composition to a substrate to give a precursor; E3. heating of the precursor to a temperature in the range from 25 to 200 C. to give the layer structure.

Claims

1. A process for producing a layer structure, which comprises the steps: E1. providing a composition comprising i. gold (Au) particles in an amount in the range from 0.1 to 50% by weight; ii. a balance to 100% by weight of a polar, protic organic solvent; iii. less than 5% by weight of water; and iv. a mercapto-carboxyl compound of the general formula (I), or a salt thereof, wherein the general formula (I) is: SHR.sub.1COOH, where R.sub.1 is a substituted, unsubstituted, branched or unbranched, cyclic or polycyclic C.sub.1-C.sub.20-hydrocarbon radical, where the % by weight, in each case based on the total mass of the composition, add up to 100% by weight; and wherein the composition has a pH in the range from 3 to 8; E2. applying the composition to a substrate to give a precursor; and E3. heating the precursor to a temperature in the range from 25 to 300 C. to give the layer structure.

2. The process as claimed in claim 1, wherein the gold particles have a diameter in the range from 1 to 25 nm.

3. The process as claimed in claim 1, wherein the viscosity of the composition is selected in the range from 1 to 100000 mPas at a temperature of 20 C.

4. The process as claimed in claim 1, wherein the protic, polar organic solvent comprises at least 20% by weight of a polyalcohol.

5. The process as claimed in claim 4, wherein the polyalcohol has from 2 to 20 carbon atoms.

6. The process as claimed in claim 4, wherein the polyalcohol is selected from the group consisting of 1,2-ethanediol, 1,2-propanediol, 1,3-propanediol, 1,2,3-propanetriol (glycerol), 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2,3-butanetriol, 1,2-dihydroxybenzene, 1,3-dihydroxybenzene, 1,4-dihydroxybenzene, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene, 1,4-dihydroxy-2,5-dinitrobenzene, L-adrenaline, a monosaccharide, a disaccharide, a monosaccharide or disaccharide in mixtures with a liquid polyol, 1,1,1-tris(hydroxymethyl)propane, 2,2-dimethylpropane-1,3-diol, a polyethylene glycol, and mixtures of at least two thereof.

7. The process as claimed in claim 1, wherein the substituted, unsubstituted, branched or unbranched, cyclic or polycyclic C.sub.1-C.sub.20-hydrocarbon radical has at least one, preferably two or all, of the following properties: e1. at least one of the carbon atoms of the C.sub.1-C.sub.20-hydrocarbon radical has been replaced by at least one nitrogen atom, an oxygen atom, a phosphorus atom, a sulfur atom, a hydroxyl group, a carboxyl group, a halide, an amine, an amide, a phosphate group, a sulfate group or a combination of at least two thereof; or e2. the C.sub.1-C.sub.20-hydrocarbon radical can be substituted by a substituted, unsubstituted, branched or unbranched, cyclic or polycyclic C.sub.1-C.sub.20-hydrocarbon radicals or the C.sub.1-C.sub.20-hydrocarbon radical can be branched; or e3. at least one of the carbon atoms of the C.sub.1-C.sub.20-hydrocarbon radical has been replaced by an aromatic radical or in the case of a 5-, 6- or 7-membered heteroaromatic ring by 1, 2, 3 or 4 nitrogen, oxygen and sulfur atoms, wherein the heteroaromatic radical can be substituted by halogen atoms, hydroxyl, nitro, amino groups, protected amino radicals, cyano, trifluoromethyl groups, hydrocarbon radicals having from 1 to 4 carbon atoms, alkoxy radicals having from 1 to 4 carbon atoms.

8. The process as claimed in claim 1, wherein the composition comprises from 0.1 to 4% by weight of the mercapto-carboxyl compound, based on the total mass of the composition.

9. The process as claimed in claim 1, wherein the mercapto-carboxyl compound is selected from the group consisting of L-cysteine, D-cysteine, -L-glutamyl-L-cysteinylglycine (glutathione), (RS)N-(2-mercapto-1-oxopropyl)glycine (tiopronin), mercaptosuccinic acid, N-acetylcysteine, thiosalicylic acid, dimercaptosuccinic acid, L-methionine, D-methionine, thiourea, 2-mercaptopropionic acid, thioglycerol, thiodipropionic acid, cystine, methyl 3-mercaptopropionate, Na thioglycolate and mixtures of at least two thereof.

10. The process as claimed in claim 1, wherein the composition comprises at least one further metal selected from the group consisting of silver (Ag), platinum (Pt), palladium (Pt), copper (Cu), rhodium (Rh) and combinations of at least two thereof.

11. The process as claimed in claim 1, wherein the composition further comprises a surface-active substance.

12. The process as claimed in claim 1, wherein a protective layer is applied at least to a part of the layer structure in a further step E4.

13. The process as claimed in claim 1, wherein the substrate is selected from the group consisting of a paper, a wood, a textile, a glass, a polymer, a metal, a ceramic, a keratinized layer and combinations of at least two thereof.

14. The process as claimed in claim 1, wherein the substrate has a conductivity of less than 10.sup.13 S/cm.

15. The process as claimed in claim 1, wherein the application of the composition in step E2 is carried out by means of a brush, a screen, a felt pen, a fountain pen or a nozzle.

16. A precursor of a layer structure obtained by means of process steps E1 and E2 of the process as claimed in claim 1.

17. The precursor as claimed in claim 16, wherein the precursor has at least one of the following properties: V1. a thickness of the substrate in the range from 0.1 mm to 5 cm; V2. a thickness of the composition applied in step E2 in the range from 0.1 m to 70 m; V3. a conductivity of the substrate of less than 10.sup.13 S/cm; or V4. a conductivity of the composition applied in step E2 in the range from 10.sup.1 S/cm to 10.sup.8 S/cm.

18. A composition comprising: z1. gold (Au) particles in an amount in the range from 0.1 to 50% by weight; z2. water in the range from 0 to 5% by weight; z3. a polar, protic, organic solvent as balance to 100% by weight; and z4. a mercapto-carboxyl compound of the general formula (I), or a salt thereof, wherein the general formula (I) is: SHR.sub.1COOH, where R.sub.1 is a substituted, unsubstituted, branched or unbranched, cyclic or polycyclic C.sub.1-C.sub.20-hydrocarbon radical, where the % by weight, in each case based on the total mass of the composition, add up to 100% by weight; and wherein the composition has a pH in the range from 3 to 8.

19. The composition as claimed in claim 18, wherein the composition comprises at least one further component selected from: z4. polyvinylpyrrolidone in an amount in the range from 0 to 10% by weight, based on the total mass of the composition; or z5. a polyalcohol in an amount in the range from 0 to 90% by weight, based on the total mass of the composition.

20. The composition as claimed in claim 19, wherein the polyalcohol is selected from the group consisting of 1,2-ethanediol, 1,2-propanediol, 1,2,3-propanetriol (glycerol), 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2,3-butanetriol, 1,2-dihydroxybenzene, 1,3-dihydroxybenzene, 1,4-dihydroxybenzene, 1,2,3-trihydroxybenzene, 1,2,4-trihydroxybenzene, 1,4-dihydroxy-2,5-dinitrobenzene, L-adrenaline, a monosaccharide, a disaccharide, a monosaccharide or disaccharide in mixtures with a liquid polyol, 1,1,1-tris(hydroxymethyl)propane, 2,2-dimethylpropane-1,3-diol, a polyethylene glycol, and mixtures of at least two thereof.

21. The composition as claimed in claim 18, wherein the gold particles have a particle size D.sub.50 of 20 nm or less.

Description

(1) In the following,

(2) FIG. 1 shows a schematic depiction of the process steps of a process according to the invention;

(3) FIG. 2a shows a schematic depiction of a precursor according to the invention;

(4) FIG. 2b shows a schematic depiction of a layer structure according to the invention;

(5) FIG. 2c shows a schematic depiction of a layer structure according to the invention with additional protective layer;

(6) FIG. 2d shows a schematic depiction of an object comprising a layer structure according to the invention;

(7) FIG. 3 shows an electron micrograph of a composition according to the invention as per example 1 sample a);

(8) FIG. 4 shows an electron micrograph of a further composition according to the invention as per example 1 sample b);

(9) FIG. 5 shows an electron micrograph of a further composition according to the invention as per example 1 sample c).

(10) FIG. 1 schematically shows the steps of the process of the invention. In step E1. 30, the composition from Example 1 is provided in a container. In step E2. 40, the composition is applied to a substrate, for example in the form of a glass plate having the dimensions 7*10 cm, by means of screenprinting through a screen having a mesh opening size of 150 m using a 70 Shore rubber doctor blade. The wet film thickness of the composition is about 20 m. The substrate together with the composition forms the precursor according to the invention. The substrate together with the composition is heated at 150 C. for 1 hour under atmospheric pressure in a hot air oven from Fisher Scientific, model UT6060, in step E3. 50. Here, a gold layer is formed from the composition and a layer structure according to the invention is obtained in this way. A protective layer in the form of a commercial transparent surface coating (e.g. clear coating for automobile coating, e.g. Profix 2K MS Klarlack CP400 or Profix 2K Klarlack Matt CM10) can optionally also be applied in step E4. 60 at least to the gold layer g formed from the composition 6 or over the entire layer structure.

(11) FIG. 2a shows a precursor 12 which consists of a substrate 4 to which a composition 6 has been applied. The substrate 4 can be, for example, a paper, a glass or a ceramic. In this example, the substrate 4 is a 1 mm thick polypropylene film having the dimensions 20*20 cm.

(12) As described for FIG. 1, a layer structure 2 as shown in FIG. 2b is formed by heating the precursor 12 shown in FIG. 2a at 50 C. This layer structure 2 consists of the substrate 4 and a gold layer 8. The gold layer has a thickness of 1 m.

(13) FIG. 2c shows the layer structure 2 as per FIG. 2b, with a protective layer 10 having additionally been applied on top of the gold layer 8. As an alternative or in addition, the protective layer 10 can also be applied to the underside of the substrate 4.

(14) FIG. 2d shows an object 20 consisting of a table plate 22 to which a layer structure 2 has been applied. The layer structure 2 comprises the substrate 4, the gold layer 8 and the protective layer 10. The layer structure 2 can have the same dimensions and materials as that described for FIGS. 2a and 2b.

(15) FIG. 3 shows a transmission electron micrograph of a composition 6 according to the invention. The composition corresponds to example 1 sample a). The magnification of the transmission electron micrographs was 45000. It can clearly be seen that the round to oval gold particles have a diameter in the range from 1 to 10 nm, with about half of the particles having a diameter of less than 5 nm, corresponding to a D.sub.50 of 4.9 nm. 10% of the particles have a diameter of 2.8 nm or less, corresponding to a D.sub.10 of 2.8 nm, and 90% of the particles have a diameter of 10.1 nm or less, corresponding to a D.sub.90 of 10.1 nm. Here, particles adhering to other particles were regarded as individual particles. The diameter was determined at a free side of the adhering particles.

(16) FIG. 4 shows an image recorded using a transmission electron microscope (TEM) of the same type as described for FIG. 3. FIG. 4 shows a composition 6 as per example 1 sample b. FIG. 4 was taken at an enlargement of 45000. It can be seen in FIG. 4 that the gold particles have diameters in the range from 3 to 16 nm, with about half of the particles having a diameter of less than 10 nm, corresponding to a D.sub.50 of 9.1 nm. 10% of the particles have a diameter of 5.5 nm or less, corresponding to a D.sub.10 of 5.5 nm, and 90% of the particles have a diameter of 15.8 nm or less, corresponding to a D.sub.90 of 15.8 nm. Here, particles adhering to other particles were regarded as individual particles. The diameter was determined at a free side of the adhering particles.

(17) FIG. 5 shows an image recorded using a transmission electron microscope of the same type as described for FIG. 3. FIG. 5 shows a composition 6 of example 1 sample c) at an enlargement of 45000. It can be seen in FIG. 5 that the gold particles have diameters in the range from 7 to 40 nm. About half of the particles have a diameter of less than 27 nm, corresponding to a D.sub.50 of 24.9 nm. Here, particles adhering to other particles were regarded as individual particles. The diameter was determined at a free side of the adhering particles.

(18) As can be seen from Table 1, the gloss of the composition 6 depends on the particle size of the Au particles. While the composition 6 in FIGS. 3 and 4 appears bright, the composition 6 in FIG. 5 displays a silk finish.

(19) The transmission electron micrographs were recorded on copper grids provided with carbon films, as are customary for transmission electron micrographs.

LIST OF REFERENCE NUMERALS

(20) 2 Layer structure 4 Substrate 6 Composition 8 Gold layer 10 Protective layer 12 Precursor 20 Object 22 Table plate 30 Step E1. 40 Step E2. 50 Step E3. 60 Step E4.