ASTM D6280-98

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Designation: D 6280 – 98
Specification for
Zinc Phosphate Pigments
This standard is issued under the fixed designation D 6280; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (e) indicates an editorial change since the last revision or reapproval.
1. Scope dihydrate (Zn (PO ) ·2H O) or a mixture of zinc phosphate
3 4 2 2
dihydrate and zinc phosphate tetrahydrate (Zn (PO ) ·4H O)
1.1 This specification covers three types of pigments com- 3 4 2 2
or predominately of zinc phosphate tetrahydrate which is free
mercially known as zinc phosphate each of which may or may
from extenders, diluents, and other pigments.
not be available in specific grades delineated by particle size or
4.2 Zinc phosphate shall be a chemically prepared pigment
oil absorption.
and shall be of such type and grade as to conform to the
1.1.1 Type I—Zinc Phosphate, dihydrate predominant.
requirements prescribed in Table 1. They shall additionally be
1.1.2 Type II—Zinc Phosphate, dihydrate tetrahydrate mix-
free of extenders, modifiers, diluents, alteration of stoichiomet-
ture.
ric chemical structure, co-reacted precipitates, and carbon-
1.1.3 Type III—Zinc Phosphate, tetrahydrate predominant.
aceous material.
2. Referenced Documents
4.3 The desired properties of the pigment, other than as
herein indicated, shall be subject to mutual agreement between
2.1 ASTM Standards:
interested parties and shall be based upon a satisfactory match
D 153 Test Method for Specific Gravity of Pigments
between any submitted sample and a previously agreed upon
D 185 Test Method for Coarse Particles in Pigments, Pastes,
reference sample.
and Paints
D 280 Test Method for Hygroscopic Moisture (and Other
5. Classification
Matter Volatile Under the Test Conditions) in Pigments
5.1 Type I—which consists predominately of zinc phosphate
D 281 Test Method for Oil Absorption of Pigments by
dihydrate (Zn (PO ) ·2H O) and exhibits a differentiating loss
3 4 2 2
Spatula Rub Out
on ignition of the dried pigment at 600 °C between 8.5 and 10.0
D 1208 Test Method for Common Properties of Certain
weight %.
Pigments
5.2 Type II—which consists essentially of a mixture of zinc
D 1210 Test Method for Fineness of Dispersion of
phosphate dihydrate (Zn (PO ) ·2H O) and Zinc Phosphate
3 4 2 2
Pigments-Vehicle Systems by Hegman-Type Gage
Tetrahydrate (Zn (PO ) ·4H O) and exhibits a differentiating
D 2448 Test Method for Water Soluble Salts in Pigments by 3 4 2 2
loss on ignition of the dried pigment at 600 °C between 10.0
Measuring the Specific Resistance of the Leachate of the
2 and 14.0 weight %.
Pigment
5.3 Type III—which consists predominately of zinc phos-
3. Significance and Use phate tetrahydrate (Zn (PO ) ·4H O) and exhibits a differenti-
3 4 2 2
ating loss on ignition of the dried pigment at 600 °C between
3.1 Zinc phosphate functions as both a chemical and a
14.0 and 18.0 weight %.
pigment. As a pigment it is used in a variety of applications
including that of corrosion inhibiting paints.
6. Sampling
4. Composition and Properties 6.1 Two samples shall be taken at random from different
packages from each lot, batch, days pack or other unit of
4.1 Zinc phosphate pigment is a white corrosion inhibiting
production in a shipment. When no markings distinguishing
pigment consisting either predominately of zinc phosphate
between units of production appear, samples shall be taken
from different packages in ratio of two samples for each 5000
This test method is under the jurisdiction of ASTM Committee D-1 on Paint
kg, except for those shipments of less than 5000 kg where two
and Related Coatings, Materials, and Applications and is the direct responsibility of
samples shall be taken. At the option of the interested party the
Subcommittee D01.31 on Pigment Specifications.
samples may be tested separately or as a composite sample
Current edition approved June 10, 1998. Published October 1998.
Annual Book of ASTM Standards, Vol 06.03.
Annual Book of ASTM Standards, Vol 06.01.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
D 6280
TABLE 1 Zinc Phosphate Pigment Properties
Property TYPE I TYPE II TYPE III
ZnO, weight percent 62.6 - 65.1 62.6 - 65.1 62.6 - 65.1
(on ignited sample)
P O , weight percent 34.9 - 37.4 34.9 - 37.4 34.9 - 37.4
2 5
(on ignited sample)
Loss on ignition, weight 8.5 - 10.0 10.0 - 14.0 14.0 - 18.0
percent (of dried pigment)
GRADE GRADE GRADE
Mean Particle Size F M C F M C F M C
(microns) < 2.5 2.5-5.0 > 5.0 same same
Oil adsorption > 30 30 - 15 < 15 same same
Matter soluble in water, 6500 6500 6500
specific resistance,
(min. ohm - cm)
Moisture and other volatile 0.5 0.5 0.5
matter (105 - 110° C)
Specific gravity, g/cm 3.0 - 3.5 3.0 - 3.5 3.0 - 3.5
Hegman grind 6 min 6 min 6 min
Coarse particle
percent residue 325 M (45 0.5 max 0.5 max 0.5 max
μm)
pH, aqueous suspension 6 - 8 6 - 8 6 - 8
formed by blending in equal quantities the samples from the 7.1.4 Coarse Particles—Test Method D 185.
same unit of production. 7.1.5 pH—Test Method D 1208.
7.1.6 Specific Resistance—Test Method D 2448.
7. Test Methods
7.1.7 Moisture—Test Method D 280.
7.1 Tests shall be conducted in accordance with the follow- 7.1.8 Chemical Analysis—Incorporated in this specification
ing test methods. Test procedures not incorporated here and not
as Annex A1 and Annex A2.
covered by ASTM test methods shall be mutually agreed upon 7.1.9 Loss on Ignition—Incorporated in this specification as
between the interested parties.
Annex A3.
7.1.1 Specific Gravity—Test Method D 153, Method B.
8. Keywords
7.1.2 Oil Absorption—Test Method D 281.
7.1.3 Hegman Grind—Test Method D 1210. 8.1 analyical; zinc; zinc phosphate
ANNEXES
(Mandatory Information)
A1. TEST METHOD FOR DETERMINATION OF ZINC CONTENT FOR ZINC PHOSPHATE TYPE PIGMENTS
A1.1 Scope establish the appropriate safety and health practices and
determine the applicability of regulatory limitations prior to
A1.1.1 This test method covers the determination of the
use.
zinc content for zinc phosphate monohydrate, dihydrate, tet-
rahydrate, or mixtures of these various crystal water content
A1.2 Reference Documents
pigments.
A1.1.2 This standard does not purport to address all the
A1.2.1 ASTM Standards:
safety concerns, if any, associated with its use. It is the
responsibility of whoever uses this standard to consult and
D 6280
Test Method for Determination of Loss on Ignition for Zinc A1.5.5 Primary Standard Zinc Oxide (0.2 N solution)—
Phosphate Type Pigments Accurately weigh 4.0690 g of oven dried ZnO. Dissolve in 250
D 1193 Specification for Reagent Water mL of the buffer solution and dilute to 500 mL. (Conversely,
you can weigh up approximately 4.0 g of ZnO, create the
A1.3 Summary of Test Method
solution, and standardize it using the primary standard grade
A1.3.1 A weighed sample taken from Annex A3, Test ZnO.)
A1.5.6 0.2 N Disodium Ethylendiaminetetraacetate Dihy-
Method for Determination of Loss on Ignition for Zinc
Phosphate Type Pigments completed analysis (that is, sample drate (EDTA)—37.2 g of EDTA per litre of aqueous solution.
contains no associated crystal water), is dissolved in ammonia
A1.6 Procedure
buffer, complexed with disodium ethylendiaminetetraacetate
A1.6.1 Weigh approximately 0.25 g ( see Annex A3) in
dihydrate (EDTA) and back titrated with a standard zinc
duplicate to the nearest 0.1 mg. Place in respective Erlenmeyer
solution to an eriochrome black T endpoint where the percent
flasks. Add 25 mL of the pH 10 buffer solution. Stir gently to
ZnO is determined.
dissolve. Pipet 50.00 mL of the EDTA solution into each
respective Erlenmeyer flask. Dilute to 200 mL with dionized
A1.4 Significance and Use
water. Add 6 to 7 drops of eriochrome Black T indicator. Titrate
A1.4.1 This test method provides a reliable means for
with the 0.2 N ZnO solution to a wine - red endpoint. Run a
determination of the percent ZnO for zinc phosphate pigments.
blank by titrating 50.00 mL EDTA containing 25 mL of pH 10
The percent ZnO content for the product gives evidence of the
buffer solution with the 0.2 N ZnO solution.
chemical purity of the pigment.
A1.7 Calculations
A1.5 Reagents and Materials
A1.7.1 Calculate the percent ZnO as follows:
A1.5.1 Purity of Reagents—Reagent grade chemicals shall
~V –V ! 3 N ZnO 3 4.069
b s
be used in this test, unless otherwise indicated. It is intended
% ZnO 5 (A1.1)
Mass of Sample
that all reagents shall conform to th
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