Quality Specifications

15 октября, 2015 Pokraskin

Many standard specifications have been laid down for the more important uses of ZnO (rubber, paints, and the pharmaceutical industry). For standards, see Table 1.1 (“Zinc oxide pigments; Methods of analysis” and “Specification”). Various methods of classification are used, often based on the production process and the chemical composition. The most well known are pharmacopeias (USP, BP; DAB, Ph. Eur.); ISO 9298, T31 006 NF, ASTM D79 — 86 and ASTM D 4295 — 89. Table 2.13 shows a classification with typical data for commercially available zinc oxide grades (more detailed standard specifications see standards mentioned above).

Tab. 2.13: Classification of commercially available grades of zinc oxide (typical data).

Parameter

Indirect Process Pharmaceutical grade

Indirect Process Chemical pure grade

Direct Process Chemical pure grade

Wet process Chemical pure grade

ZnO (wt.%)

99.5

99.0

98.5

93

Pb (wt.%)

0.005

0.2

0.2

0.001

Cd (wt.%)

0.001

0.01

0.005

0.001

Cu (wt.%)

0.0005

0.001

0.005

0.001

Mn (wt.%)

0.0002

0.0005

0.005

0.001

Loss on ignition

0.2

0.25

0.25

1-5

(wt.%)

Specific surface

3-10

3-10

1-4

3-80

area (m2 g-1) Sieve residue

0.02

0.04

0.02

0.1

(%, 320 mesh)

Normally manufactures have their own standards. The terms gold seal, silver seal, red seal, green seal and white seal are still common in Europe.

2.3.5

Опубликовано в рубрике Industrial Inorganic Pigments
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