PCD - A new white colour in Cosmetic Industry:Trivalent chromium (Cr(III)).

A NEW WHITE COLOUR IN COSMETIC INDUSTRY:

TRIVALENT CHROMIUM (CR(III)).

Conference by Serge Brigot for Graindorge at PCD in February, 2015

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Some Definitions:

• Chromium (0)White metal with high corrosion and tarnish resistance.

• Chrome plate process using the Hexavalent chromium form Cr(VI) in electrolytic solution to obtain the chrome metal form (0).

(decorative,automotive,mecanical use,)

• Chromatation Chemical conversion ,using the hexavalent form,use to increase the corrosion resistance after Zinc electroplating for example,

(Automotiv in the past,military use …)

Only chrome metal = without any Cr(VI)

Cr(VI) on the top

Toxicological Profile for Hexavalent Chromium

• Formula: Chromic trioxyde: Cr03,

• Physical state,appearance: Odourless,dark red crystals,flakes or granular powder

:

• Chemicals Properties: the substance decompose above 250 °C to chromic oxide and oxygen,which increases fire azard,The

substance is a strong oxidant and reacts violently with combustible and reducing materials causing fire and explosion hazard.

• Hazard Pictograms:

• Risks: the substance is corrosive to the eyes,skin and the respiratory tracts.Corrosive on ingestion,This substance is carcinogenic to human,may cause heritable genetic damage to human germ cells,Toxic for human reproduction or development.

O - Comburant T+ - Très toxique

Trivalent Chrome

Hexavalent Chrome alternative

Toxicological Profile for Chrome sulfate (trivalent chrome)

• Formula: Cr2(SO4)3,6H2O

• Hazard and Pictogram: ?

• Risks: ?

Comparaison hexavalent/trivalent chrome

- Work Station -Hexavalent Trivalent

Carcinogenic Not carcinogenic

Lead Compound Formation Without any lead compound formation

Standard Rectifier for electric power High tension Rectifier

High tolerance for Metallics Impurities Not at all tolerance for M.I

3 steps for waste treatment 1 step

Trivalent Chrome

MétalMaximal concentrations

in the bath

Nickel < 100 ppm

Cupper < 10 ppm

Iron < 60 ppm

Zinc < 5 ppm

Lead < 10 ppm

The electrolytic bath need more cleaning treatment.

Tolerance for Metallics Impurities:

Comparative Degree of white colour by Lab measurement.

-8

-6

-4

-2

0

2

4

6

8

-1 -0,9 -0,8 -0,7 -0,6 -0,5 -0,4 -0,3 -0,2 -0,1 0 0,1 0,2 0,3 0,4 0,5 0,6 0,7 0,8 0,9 1

Hex. ChromeL=83,69

SilverL=97,49

Chrome 3L=80,05

NickelL=81,56

White bronzeL=83,94

Red

Yellow

Blue

Green

L*: Black (0) White (100) a*: Green (-) Red (+) b*: Blue (-) Yellow (+)

Conclusions

• Sustainable developement,important reduction of the impact on the environment.

• Cost of plating a few higher.• Important step in the reduction of CMR substances.• The etching step in the attack of ABS is still using the

Cr(VI) form ,but we can be hopeful of a good outcome in that regard.