阅读说明：本技术 用于通过有机纳米层保护贵金属基底的组合物和方法 (Compositions and methods for protecting noble metal substrates through organic nanolayers ) 是由 科琳·内利亚斯 玛丽安娜·巴托雷蒂 于 2020-03-06 设计创作，主要内容包括：本发明涉及用于保护贵金属基底的组合物以及在贵金属基底上获得有机保护纳米层的方法。此外,本发明涉及具有有机保护纳米层的贵金属基底。(The present invention relates to a composition for protecting a noble metal substrate and a method for obtaining an organic protective nanolayer on a noble metal substrate. Furthermore, the present invention relates to a noble metal substrate having an organic protective nanolayer.)

1. A composition for protecting a precious metal substrate selected from gold, palladium, silver, platinum, rhodium, ruthenium and alloys thereof with each other and other alloy formations, against the transfer of colour and other additives from leather, wherein the composition is an aqueous solution comprising:

a) at least one compound of the general formula I

Wherein

R₁Or R₂Is independently selected from

A mercapto group, a hydroxyl group,

the presence of hydrogen in the gas phase,

alkyl, hydroxyalkyl, alkoxy and alkoxyalkyl, alkylthio and alkylthioalkyl, where each is C₁-C₁₂And is straight-chain or branched,

aralkyl, allyl or acetyl, where each is unsubstituted or substituted,

selected from amino, monoalkylamino and dialkylamino groups,Nitrogen functions of aminoalkyl, monoalkylaminoalkyl, dialkylaminoalkyl and corresponding ammonium functions at straight-chain or branched alkyl, where each is C₁-C₁₂And are and

a combination thereof, and

sodium, potassium and ammonium salts thereof, and

b) at least one buffering agent.

2. The composition according to claim 1, wherein the composition,

characterized in that R is₁And R₂Independently of one another, are selected from

A mercapto group, a hydroxyl group,

the presence of hydrogen in the gas phase,

linear and branched alkyl, alkoxy, where each is independently of the others C₁-C₃In the above-mentioned manner, the first and second substrates are,

primary and secondary amino groups, where each is independently of the other C₁-C₅In the above-mentioned manner, the first and second substrates are,

linear or branched alkylthio, where each is independently of the other C₁-C₈One of, and

a combination thereof, and (c) a combination thereof,

preferably selected from

A mercapto group, a hydroxyl group,

the presence of hydrogen in the gas phase,

alkoxy, where each of them is independently of the other C₁-C₃In the above-mentioned manner, the first and second substrates are,

primary and secondary amino groups, where each is independently of the other C₁-C₃In the above-mentioned manner, the first and second substrates are,

linear or branched alkylthio, where each is independently of the other C₁-C₆One of, and

a combination thereof.

3. The composition according to any one of claims 1 or 2,

characterized in that said compound has the general formula II:

wherein

R is selected from

A mercapto group, a hydroxyl group,

the presence of hydrogen in the gas phase,

alkyl, hydroxyalkyl, alkoxy and alkoxyalkyl, alkylthio and alkylthioalkyl, where each is C₁-C₁₂And is straight-chain or branched,

aralkyl, allyl or acetyl, where each is unsubstituted or substituted,

nitrogen functions chosen from amino, monoalkylamino and dialkylamino, aminoalkyl, monoalkylaminoalkyl, dialkylaminoalkyl groups and corresponding ammonium functions at linear or branched alkyl groups, where each is C₁-C₁₂And are and

a combination thereof.

4. The composition according to any one of claims 1 to 3,

characterized in that said compound has the general formula II:

wherein

R is selected from

A mercapto group, a hydroxyl group,

the presence of hydrogen in the gas phase,

alkyl, hydroxyalkyl, alkoxy and alkoxyalkyl, alkylthio and alkylthioalkyl, where each is C₁-C₁₂And is straight-chain or branched,

aralkyl, allyl or acetyl, where each is unsubstituted or substituted,

a combination thereof.

5. The composition according to any one of claims 1 to 4,

characterized in that said compound is selected from

5-methylthio-1, 3, 4-thiadiazole-2-thiol, in which R is₁＝CH₃S and R₂＝SH，

5-methyl-1, 3, 4-thiadiazole-2-thiol, wherein R is₁＝CH₃，R₂＝SH，

2-amino-5-methyl-1, 3, 4-thiadiazole, in which R is₁＝CH₃，R₂＝NH₂，

1,3, 4-thiadiazole-2, 5-dithiol, in which R is₁＝R₂Is equal to SH, and

their sodium, potassium and ammonium salts.

6. The composition according to any one of claims 1 to 5,

characterized in that the compound of formula I or II is present partly in its oxidatively coupled form (formula III), i.e. as a disulfide, preferably disodium bis (1,3, 4-thiadiazol-2-yl) disulfide-5, 5' -dithiolate (formula III, R ═ SNa)

7. The composition according to any one of claims 1 to 6,

characterized in that the concentration of the compound of formula I, formula II or formula III is 5 to 500mmol/L, preferably 10 to 250mmol/L, more preferably 15 to 100 mmol/L.

8. The composition according to any one of claims 1 to 7,

characterized in that the buffer is selected from

Citric acid and its salts, and the salts thereof,

phosphoric acid and its salts, and salts thereof,

boric acid and its salts, and salts thereof,

monocarboxylic, dicarboxylic and tricarboxylic acids and salts thereof, preferably selected from formic acid and salts thereof, acetic acid and salts thereof and rochelle salts, and

a combination thereof, and (c) a combination thereof,

wherein the concentration of the buffer in the composition is preferably from 1 to 100g/L, more preferably from 5 to 70g/L, most preferably from 10 to 50 g/L.

9. The composition according to any one of claims 1 to 8,

characterised in that the composition has a pH of from 2 to 10, preferably from 4 to 8, more preferably from 5 to 7.

10. The composition according to any one of claims 1 to 9,

characterised in that the only solvent in the composition is water.

11. A process for obtaining an organically protected nanolayer on a noble metal substrate wherein the substrate is exposed to the composition of any one of claims 1 to 10.

12. The method of claim 11, wherein the first and second light sources are selected from the group consisting of,

characterised in that the substrate is exposed to the composition by immersion preferably for at least 5 minutes, more preferably from 10 to 30 minutes, most preferably from 15 to 20 minutes.

13. The method according to any one of claims 11 or 12,

characterized in that the substrate is exposed to the composition under cathodic and/or anodic polarization, preferably in the form of a pulsed current.

14. The method of any one of claims 11 to 13,

characterised in that after exposing the substrate to the composition, the substrate is exposed to water for cleaning, preferably by immersion.

15. The method of any one of claims 11 to 14,

characterized in that the noble metal substrate comprises or consists of a noble metal selected from the group consisting of gold, palladium, platinum, ruthenium and alloys thereof.

16. A noble metal substrate having an organic protective nanolayer as a protective layer obtainable by the method according to any one of claims 10 to 14.

17. A product comprising a noble metal substrate and a leather part, wherein the noble metal substrate has an organic protective nanolayer as a protective layer obtainable by the method according to any one of claims 11 to 15.

18. The product of claim 17, wherein said composition is in the form of a tablet,

characterized in that said product is selected from the group consisting of bags, shoes, jewelry, accessories and combinations thereof.

Examples

To illustrate the formation of organic protective nanolayers from solutions of substituted 1,3, 4-thiadiazole heterocycles on noble metal surfaces introduced in the above description of the invention, Tip Enhanced Raman Spectroscopy (TERS) and Scanning Tunneling Microscope (STM) studies were performed to monitor the quality and morphology of SAMs developed in the process. Furthermore, atomic force imaging (AFM) is also applied.

1) Sample preparation

A set of wafers with 100nm Au deposited on cleaved mica by thermal evaporation under vacuum was used as the substrate.

By adding H at 4.9mL₂To O was added 100 μ L of a solution containing the thiazole compound and a conducting salt/buffer to prepare a starting solution. The final concentration of active compound was 50mM (except for compounds 1 and 2) and the mixture was heated for homogenization.

For passivation, a brass faceplate from Ossian (5.0x 3.5cm x 0.3cm thickness) was used, on which the different layers given below were plated.

White bronze

Furthermore, white bronze is a commercial product from Coventya, under the name Auralloy 450LF, which is a Cu-Sn-Zn lead-free alloy plated from cyanide-based plating solutions. The composition of the ternary alloy is in the following range (wt.%):

Cu：51-55％

Sn：28-31％

Zn：14-19％。

the solution consisted of the following commercial products:

AURALLOY 450LF PAE

AURALLOY 450LF BRIGHENER: 3 to 5mL/L

AURALLOY 450LF SURFACT: 1.5 to 3mL/L

Yellow bronze

Furthermore, the yellow bronze is a commercial product from Coventya, named Auralloy 270LF or Auralloy 250LF, which is a Cu-Sn-Zn lead-free alloy plated from cyanide-based plating solutions. The composition of the ternary alloy is in the following range (wt.%):

Cu：70-80％

Sn：15-23％

Zn：3-10％。

gold (Au)

The gold underlayer is prepared from a typical acidic gold bath. This acid gold-based Coventya reference is PARADOR 9812 NF.

The gold substrate was flame cured and then soaked in the solution for 15 minutes. A first rinse is then performed with water, followed by placing the sample in pure water for at least 30 minutes.

The different conditions used for the samples are listed in table 1 below.

TABLE 1

2) Sample characterization

To obtain a spectrum of molecules, specific wavelengths are applied to collect the response of the molecules in frequency, the specific response of the molecules being dependent on the binding forces between atoms within the molecules.

For molecule 1 shown in fig. 1, three specific peaks were obtained, corresponding to the vibrations of N ═ N and S — C bonds, included at 1400cm^-1A strong response, which is characteristic of thiadiazole heterocycles.

These responses are also present for molecule 2 shown in figure 2, although not as apparent as the first example.

Example 1

Molecule 1

As a first step, an image of STM (scanning tunneling microscope) of the protected gold surface is obtained in order to screen the obtained nanolayers and to obtain a surface area that can be further characterized. FIG. 3 shows the measurement at 300X 300nm²Characteristic image obtained on the surface (sample 1). We can observe on fig. 3 that on the surface we obtain white nanoparticles, which in the following description will be referred to as clusters. These clusters may be small oligomers that form in solution and deposit on the substrate during nanolayer formation. Notably, these clusters remained after water washing, indicating that the bond between the nanolayer and the gold atoms was strong. Due to the TERS analysis, cluster composition and the presence of a nanolayer on a homogenous portion of the surface (referred to as a homogenous surface) can be identified.

The TERS spectrum of clusters or homogeneous regions is obtained in order to highlight the presence of organic nanolayers on both regions. For this purpose, an STM scan image is performed, stopping the scan when a cluster is identified. Spectra were then recorded for 20 seconds at and around the clusters and showed similar responses at different intensities (see fig. 4 and 5).

TERS analysis of clusters bonded to surfaces and planar surfaces confirmed the presence of five-membered heterocyclic compounds. In fact, when analyzing the gold surface that has been treated with the five-membered heterocyclic compound solution, the peaks previously identified as characteristic in the solution are again found (fig. 1). At 1075cm^-1And 1400cm^-1Significant lines were found nearby. The results highlight the uniform presence of 2, 5-dimercapto-1, 3, 4-thiadiazole across the surface, with a heterogeneous distribution in view of oligomer formation in the solution. However, the spectrum on a flat surface exhibits two significant peaks as defined in FIG. 1, the effect of 2, 5-dimercapto-1, 3, 4-thiadiazole in solutionThis should confirm the presence of the molecules on the planar surface.

Example 2

Molecule 2

Similar studies were performed to confirm the presence of 5-amino-2-mercapto-1, 3, 4-thiadiazole on the gold surface.

Operating conditions for depositing the nanolayers:

substrate wafer made by deposition of 100nm Au on cleaved mica by thermal evaporation under vacuum

- [ 5-amino-2-mercapto-1, 3, 4-thiadiazole ] ═ 50mM in water

-pH＝10

-temperature 40 deg.c

Immersion time 15 minutes

Flushing with demineralized water (30 minutes)

STM-TERS analysis (FIG. 6) was performed on a gold surface previously immersed in a solution of molecule 2, shown at 1413cm^-1There was a slight response indicating the presence of the thiadiazole compound. Although the spectral background is more crowded than in previous analyses, the signal is important because the results are well reproduced.

Example 3

Molecule 1 deposited in citrate/citric acid medium

The benefits of introducing conductive salts have been demonstrated by AFM and TERS analysis. Two samples were analyzed:

operating conditions for obtaining the nanolayer of sample 1 (fig. 7):

substrate wafer made by deposition of 100nm Au on cleaved mica by thermal evaporation under vacuum

- [ disodium 2, 5-dimercapto-1, 3, 4-thiadiazole ] ═ 50mM in water

-pH＝5

-temperature 40 deg.c

Immersion time 15 minutes

Flushing with demineralized water (30 minutes)

Operating conditions for obtaining the nanolayer of sample 2 (fig. 8):

substrate wafer made by deposition of 100nm Au on cleaved mica by thermal evaporation under vacuum

- [ disodium 2, 5-dimercapto-1, 3, 4-thiadiazole ] ═ 50mM in water

- [ potassium citrate ] ═ 25g/L

- [ citric acid ] ═ 7g/L

-pH＝5

-temperature 40 deg.c

Immersion time 15 minutes

Flushing with demineralized water (30 minutes)

A comparison of fig. 7 and 8 shows that with the introduction of the conductive salt, the clusters are no longer present or significantly reduced. The TERS analysis confirmed that the heterocyclic compound was strongly bound to the surface.

The enlarged image is shown in fig. 9.

In the presence of buffer/conducting salt (such as filament), the nanolayers apparently form different structures, and without this component, the SAM structure is in the form of clusters (white dots on FIG. 7).

3) Corrosion test

To demonstrate the improvement obtained by applying the innovative organic protective nanolayers compared to the prior art (octadecanethiol or 1-hexadecanethiol), it has been shown in the examples below that the nickel-free plating sequence can now be actively protected against interaction with leather using organic nanolayers.

Substrates for passivation applications:

plated brass (>15 μm)

White bronze >2 μm

Yellow bronze >3 μm

0.5 μm gold

The reference tests followed standard conditions (ISO 4611-96 hours), leather was introduced below the metal surface in the following medium:

3 minutes before the test

-black soft leather

Temperature 55 ℃ below zero

-humidity 95%

TABLE 2

Octadecanethiol and 1-hexadecanethiol were used as references for these tests, since they are compounds from the prior art (WO2009067446A 1). Octadecanethiol was applied at 7V for 10 minutes without and with cathodic polarization; 1-Hexadecylthiol was applied for 30 minutes.

The test results obtained with the prior art compounds and the different heterocyclic compounds are shown in tables 3 and 4 below.

TABLE 3

TABLE 4

Optimized operating conditions have been established to reproduce the properties of different working surfaces other than gold and gold alloys, in order to show that these metals also do not have a color transfer due to the application of the organic nanolayers.

Substrates for passivation applications:

plated brass (>15 μm)

-white bronze >4 μm

-working of the surface

The test results are shown in tables 5 and 6 below.

TABLE 5

TABLE 6

In FIG. 10, a noble metal substrate of the prior art without a protective nanolayer is shown. The sample showed darker areas as a result of color transfer from the darker leather to the substrate.

On the other hand, FIG. 11 shows a noble metal substrate of the present invention. The substrate showed a uniformly colored surface without any dark areas. Due to the protective nanolayer of the present invention, color transfer from leather to the noble metal substrate has been completely avoided.