Electroplating bath and method for producing dark chromium layers

Patent metadata

Field	Value
Publication number	US-9689081-B2
Application number	US-201214113247-A
Country	US
Kind code	B2
Filing date	Apr 27, 2012
Priority date	May 3, 2011
Publication date	Jun 27, 2017
Grant date	Jun 27, 2017

Abstract

The invention relates to methods and plating baths for electrodepositing a dark chromium layer on a workpiece. The trivalent chromium electroplating baths comprise sulphur compounds and the methods for electrodepositing a dark chromium layer employ these trivalent chromium electroplating baths. The dark chromium deposits and workpieces carrying dark chromium deposits are suited for application for decorative purposes.

First claim

The invention claimed is:

1. An electroplating bath for deposition of a dark chromium layer on a workpiece, the electroplating bath comprising:
(A) trivalent chromium ions;
(B) carboxylate ions;
(C) at least one pH buffer substance; and
(D) at least one coloring agent,
wherein the at least one coloring agent comprises a coloring agent selected from:
2-Amino-4-methanesulfinyl-butyric acid,
1,1-Dioxo-1,2-dihydro-1lambda*6*-benzo[d]isothiazol-3-one,
Prop-2-yne-1-sulfonic acid,
Methanesulfinylmethane, and
2-(1,1,3-Trioxo-1,3-dihydro-1lambda*6*-benzo[d]isothiazol-2-yl)-ethanesulfonic acid, and
wherein the at least one coloring agent optionally further comprises at least one coloring agent selected from sulphur containing compounds having the general Formula (II):

wherein
═X represents ═O, or a free electron pair;
R 3 represents —R 5 , —CH═CH 2 , —CH 2 —CH═CH 2 , —CH═CH—CH 3 , —CH 2 —CH 2 —CH═CH 2 , —CH 2 —CH═CH—CH 3 , —CH═CH—CH 2 —CH 3 , —C≡CH, —CH 2 —C≡CH, —C≡C—CH 3 , —CH 2 —CH 2 —C≡CH, —CH 2 —C≡C—CH 3 , —C≡C—CH 2 —CH 3 , —C(—NH 2 )═NH,

R 4 represents —R 5 , —OR 5 , —(CH 2 —)r—CH(—NH 2 )—COOH, —(CH 2 —)r—CH(—NH—CH 3 )—COOH, —(CH 2 —)r—CH(—N(—CH 3 ) 2 )—COOH, —(CH 2 —)r—CH(—NH 2 )—CO—OCH 3 , or —(CH 2 —)r—CH(—NH 2 )—CO—OCH 2 —CH 3;
R 5 represents —H, —CH 3 , —CH 2 —CH 3 —CH 2 —CH 2 —CH 3 or —CH 2 —CH 2 —CH 2 —CH 3 ;
r is an integer from 0 to 4 or;
R 3 and R 4 taken together represent a linear chain structure in order to build one of the following ring structures including the central sulphur atom of Formula (II):

R 10 represents, —CH 3 , or —CH 2 —CH 3 ;
or salts, tautomeric forms, betaine structures thereof; and
(E) ferrous ions.

2. The electroplating bath according to claim 1 , wherein the at least one coloring agent further comprises the coloring agent wherein
R 3 and R 4 taken together represent the linear chain structure in order to build one of the following ring structures including the central sulphur atom of Formula (II):

wherein R 10 represents, —CH 3 , or —CH 2 —CH 3 .

3. The electroplating bath according to claim 1 , further comprising chloride ions.

4. The electroplating bath according to claim 1 , wherein the concentration of the coloring agent according to general Formula (II) ranges from 0.01 g/L to 100 g/L.

5. The electroplating bath according to claim 1 , wherein the concentration of the ferrous ions ranges from 40 mg/L to 280 mg/L.

6. The electroplating bath according to claim 1 , wherein the bath is free of compounds containing phosphorus.

7. The electroplating bath according to claim 1 , wherein the electroplating bath further comprises at least one coloring agent selected from sulphur containing compounds having the general Formula (I):

wherein
n, p, q are independently of each other integers from 0 to 4;
R 1 represents —H, —OH, —COOH, —CO—OCH 3 , —CO—OCH 2 —CH 3 , —(—O—CH 2 —CH 2 —)m—OH, —CH(—NH 2 )—COOH, —CH(—NH—CH 3 )—COOH, —CH(—N(—CH 3 ) 2 )—COOH, —CH(—NH 2 )—CO—OCH 3 , —CH(—NH 2 )—CO—OCH 2 —CH 3 , —CH(—NH 2 )—CH 2 —OH, —CH(—NH—CH 3 )—CH 2 —OH, —CH(—N(—CH 3 ) 2 )—CH 2 —OH, or —SO 3 H;
m represents an integer from 5 to 15;
R 2 represents —H, —OH, —(CH 2 —) p —OH, —(CH 2 —) p —C(—NH 2 )═NH, —CH 2 —CH 2 —(—O—CH 2 —CH 2 —) m —OH, —R 5 , —(CH 2 —) q —COOH, —(CH 2 —) q —CO—OCH 3 , —(CH 2 —) q —CO—OCH 2 —CH 3 , —(CH 2 —)q—S—(CH 2 —) 2 —OH, —CS—CH 3 , —CS—CH 2 —CH 3 , —CS—CH 2 —CH 2 —CH 3 , —CN,

R 1 and R 2 together represent a linear chain structure in order to build one of the following ring structures including the central sulphur atom of Formula (I):

R 5 represents —H, —CH 3 , —CH 2 —CH 3 , —CH 2 —CH 2 —CH 3 , or —CH 2 —CH 2 —CH 2 —CH 3 ;
R 6 , R 7 , R 8 , R 9 represent independently of each other —H, —NH 2 , —SH, —OH, —CH 3 , —CH 2 —CH 3 , —COOH, or —SO 3 H.

8. The electroplating bath according to claim 7 , wherein the coloring agent according to Formula (I) is selected from the group of sulphur containing compounds comprising:
(1) 2-(2-Hydroxy-ethylsulfanyl)-ethanol,
(2) Thiazolidine-2-carboxylic acid,
(3) Thiodiglycol ethoxylate,
(4) 2-Amino-3-ethylsulfanyl-propionic acid,
(5) 3-(3-Hydroxy-propylsulfanyl)-propan-1-ol,
(6) 2-Amino-3-carboxymethylsulfanyl-propionic acid,
(7) 2-Amino-4-methylsulfanyl-butan-1-ol,
(8) 2-Amino-4-methylsulfanyl-butyric acid,
(9) 2-Amino-4-ethylsulfanyl-butyric acid,
(10) 3-Carbamimidoylsulfanyl-propane-1-sulfonic acid,
(11) 3-Carbamimidoylsulfanyl-propionic acid,
(12) Thiomorpholine,
(13) 2-[2-(2-Hydroxy-ethylsulfanyl)-ethylsulfanyl]-ethanol,
(14) 4,5-Dihydro-thiazol-2-ylamine,
(15) Thiocyanic acid.

9. The electroplating bath according to claim 7 , wherein the concentration of the coloring agent according to general Formula (I) ranges from 0.01 g/L to 100 g/L.

10. A method for electrodepositing a dark chromium layer on a workpiece which comprises electroplating said workpiece with the electroplating bath as defined in claim 1 .

Assignees

• Schulz Klaus-Dieter
• Wachter Philipp
• Hartmann Philip
• Atotech Deutschland Gmbh

Inventors

• Schulz Klaus-Dieter
• Wachter Philipp
• Hartmann Philip

Classifications

• C25D3/06 Primary

  from solutions of trivalent chromium · CPC title

• C25D3/10 Primary

  characterised by the organic bath constituents used · CPC title

• C25D3/08

  Deposition of black chromium {, e.g. hexavalent chromium, CrVI} · CPC title