Process for metallizing nonconductive plastic surfaces
View Patent ↗The present invention relates to a process for metallizing electrically nonconductive plastic surfaces of articles. During the process, the rack to which the said articles are fastened is subjected to a treatment for protection against metallization. Subsequently, the articles are metallized by means of known processes, wherein the racks remain free of metal.
1. Process for metallizing electrically nonconductive plastic surfaces of articles, comprising the separate process steps of:
A) fastening the article to a rack,
B) etching the plastic surface with an etching solution;
C) treating the plastic surface with a solution of a metal colloid or of a compound of a metal, the metal being selected from the metals of transition group I of the Periodic Table of the Elements and transition group VIII of the Periodic Table of the Elements, and
D) metallizing the plastic surface with a metallizing solution;
wherein the rack is treated with a solution comprising iodate ions and the treatment of the rack with a solution comprising iodate ions is performed prior to process step C).
2. Process according to claim 1 , wherein the treatment of the rack with a solution comprising iodate ions
takes place prior to process step A) or
takes place between process steps A and B) or
takes place between process steps B) and C).
3. Process according to claim 1 , wherein the following further process step is performed between process steps A) and B):
A i) treating the plastic surface in an aqueous solution comprising at least one glycol compound.
4. Process according to claim 3 , wherein the at least one glycol compound is selected from compounds of the general formula (I)
wherein
n is an integer from 1 to 4; and
R 1 and R 2 are each independently —H, —CH 3 , —CH 2 —CH 3 , —CH 2 —CH 2 —CH 3 , —CH(CH 3 )—CH 3 , —CH 2 —CH 2 —CH 2 —CH 3 , —CH(CH 3 )—CH 2 —CH 3 , —CH 2 —CH(CH 3 )—CH 3 , —CH 2 —CH 2 —CH 2 —CH 2 —CH 3 , —CH(CH 3 )—CH 2 —CH 2 —CH 3 , —CH 2 —CH(CH 3 )—CH 2 —CH 3 , —CH 2 —CH 2 —CH(CH 3 )—CH 3 , —CH(CH 2 —CH 3 )—CH 2 —CH 3 , —CH 2 —CH(CH 2 —CH 3 )—CH 3 , —CO—CH 3 , —CO—CH 2 —CH 3 , —CO—CH 2 —CH 2 —CH 3 , —CO—CH(CH 3 )—CH 3 , —CO—CH(CH 3 )—CH 2 —CH 3 , —CO—CH 2 —CH(CH 3 )—CH 3 , —CO—CH 2 —CH 2 —CH 2 —CH 3 .
5. Process according to claim 1 , wherein the plastic surface has been manufactured from at least one electrically nonconductive plastic and the at least one electrically nonconductive plastic is selected from an acrylonitrile-butadiene-styrene copolymer, a polyamide, a polycarbonate and a mixture of an acrylonitrile-butadiene-styrene copolymer with at least one further polymer.
6. Process according to claim 1 , wherein the following further process step is performed between process steps B) and C):
B i) treating the plastic surface in a solution comprising a reducing agent for manganese dioxide.
7. Process according to claim 6 , wherein the reducing agent for manganese dioxide is selected from hydroxylammonium sulphate, hydroxylammonium chloride and hydrogen peroxide.
8. Process according to claim 1 , wherein the iodate ions are in the form of metal iodates.
9. Process according to claim 8 , wherein the metal iodates are selected from sodium iodate, potassium iodate, magnesium iodate, calcium iodate and the hydrates thereof.
10. Process according to claim 8 , wherein the concentration of the metal iodates is between 5 g/l and 50 g/l.
11. Process according to claim 1 , wherein the solution comprising iodate ions further comprises an inorganic acid.
12. Process according to claim 11 , wherein the inorganic acid is selected from sulphuric acid and phosphoric acid.
13. Process according to claim 11 , wherein the inorganic acid is in a concentration ranging from 0.02 mol/l to 2.0 mol/l based on a monobasic acid.
14. Process according to claim 1 , wherein the treatment of the rack with a solution comprising iodate ions takes between 1 and 20 minutes.
15. Process according to claim 1 , wherein the treatment of the rack with a solution comprising iodate ions is executed at a temperature between 20° C. and 70° C.
16. Process according to claim 2 , wherein the following further process step is performed between process steps A) and B):
A i) treating the plastic surface in an aqueous solution comprising at least one glycol compound.
17. Process according to claim 16 , wherein the at least one glycol compound is selected from compounds of the general formula (I)
wherein
n is an integer from 1 to 4; and
R 1 and R 2 are each independently —H, —CH 3 , —CH 2 —CH 3 , —CH 2 —CH 2 —CH 3 , —CH(CH 3 )—CH 3 , —CH 2 —CH 2 —CH 2 —CH 3 , —CH(CH 3 )—CH 2 —CH 3 , —CH 2 —CH(CH 3 )—CH 3 , —CH 2 —CH 2 —CH 2 —CH 2 —CH 3 , —CH(CH 3 )—CH 2 —CH 2 —CH 3 , —CH 2 —CH(CH 3 )—CH 2 —CH 3 , —CH 2 —CH 2 —CH(CH 3 )—CH 3 , —CH(CH 2 —CH 3 )—CH 2 —CH 3 , —CH 2 —CH(CH 2 —CH 3 )—CH 3 , —CO—CH 3 , —CO—CH 2 —CH 3 , —CO—CH 2 —CH 2 —CH 3 , —CO—CH(CH 3 )—CH 3 , —CO—CH(CH 3 )—CH 2 —CH 3 , —CO—CH 2 —CH(CH 3 )—CH 3 , —CO—CH 2 —CH 2 —CH 2 —CH 3 .
18. Process according to claim 2 , wherein the following further process step is performed between process steps B) and C):
B i) treating the plastic surface in a solution comprising a reducing agent for manganese dioxide.
19. Process according to claim 3 , wherein the following further process step is performed between process steps B) and C):
B i) treating the plastic surface in a solution comprising a reducing agent for manganese dioxide.
20. Process according to claim 16 , wherein the following further process step is performed between process steps B) and C):
B i) treating the plastic surface in a solution comprising a reducing agent for manganese dioxide.