ASTM D6280-98(2014)

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Designation: D6280 − 98 (Reapproved 2008) D6280 − 98 (Reapproved 2014)
Standard Specification for
Zinc Phosphate Pigments
This standard is issued under the fixed designation D6280; 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 (´) indicates an editorial change since the last revision or reapproval.
1. Scope
1.1 This specification covers three types of pigments commercially known as zinc phosphate each of which may or may not be
available in specific grades delineated by particle size or oil absorption.
1.1.1 Type I—Zinc Phosphate, dihydrate predominant.
1.1.2 Type II—Zinc Phosphate, dihydrate tetrahydrate mixture.
1.1.3 Type III—Zinc Phosphate, tetrahydrate predominant.
1.2 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.
2. Referenced Documents
2.1 ASTM Standards:
D153 Test Methods for Specific Gravity of Pigments
D185 Test Methods for Coarse Particles in Pigments
D280 Test Methods for Hygroscopic Moisture (and Other Matter Volatile Under the Test Conditions) in Pigments
D281 Test Method for Oil Absorption of Pigments by Spatula Rub-out
D1193 Specification for Reagent Water
D1208 Test Methods for Common Properties of Certain Pigments
D1210 Test Method for Fineness of Dispersion of Pigment-Vehicle Systems by Hegman-Type Gage
D2448 Test Method for Water-Soluble Salts in Pigments by Measuring the Specific Resistance of the Leachate of the Pigment
3. Significance and Use
3.1 Zinc phosphate functions as both a chemical and a pigment. As a pigment it is used in a variety of applications including
that of corrosion inhibiting paints.
4. Composition and Properties
4.1 Zinc phosphate pigment is a white corrosion inhibiting pigment consisting either predominately of zinc phosphate dihydrate
(Zn (PO ) ·2H O) or a mixture of zinc phosphate dihydrate and zinc phosphate tetrahydrate (Zn (PO ) ·4H O) or predominately
3 4 2 2 3 4 2 2
of zinc phosphate tetrahydrate which is free from extenders, diluents, and other pigments.
4.2 Zinc phosphate shall be a chemically prepared pigment and shall be of such type and grade as to conform to the requirements
prescribed in Table 1. They shall additionally be free of extenders, modifiers, diluents, alteration of stoichiometric chemical
structure, co-reacted precipitates, and carbonaceous material.
4.3 The desired properties of the pigment, other than as herein indicated, shall be subject to mutual agreement between
interested parties and shall be based upon a satisfactory match between any submitted sample and a previously agreed upon
reference sample.
5. Classification
5.1 Type I—which consists predominately of zinc phosphate dihydrate (Zn (PO ) ·2H O) and exhibits a differentiating loss on
3 4 2 2
ignition of the dried pigment at 600°C between 8.5 and 10.0 weight %.
This specification is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.31 on Pigment Specifications.
Current edition approved Nov. 1, 2008Dec. 1, 2014. Published November 2008December 2014. Originally approved in 1998. Last previous edition approved in 20032008
as D6280 – 98 (2003).(2008). DOI: 10.1520/D6280-98R08.10.1520/D6280-98R14.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6280 − 98 (2014)
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
5.2 Type II—which consists essentially of a mixture of zinc phosphate dihydrate (Zn (PO ) ·2H O) and Zinc Phosphate
3 4 2 2
Tetrahydrate (Zn (PO ) ·4H O) and exhibits a differentiating loss on ignition of the dried pigment at 600°C between 10.0 and 14.0
3 4 2 2
weight %.
5.3 Type III—which consists predominately of zinc phosphate tetrahydrate (Zn (PO ) ·4H O) and exhibits a differentiating loss
3 4 2 2
on ignition of the dried pigment at 600°C between 14.0 and 18.0 weight %.
6. Sampling
6.1 Two samples shall be taken at random from different packages from each lot, batch, days pack or other unit of production
in a shipment. When no markings distinguishing between units of production appear, samples shall be taken from different
packages in ratio of two samples for each 5000 kg, except for those shipments of less than 5000 kg where two samples shall be
taken. At the option of the interested party the samples may be tested separately or as a composite sample formed by blending in
equal quantities the samples from the same unit of production.
7. Test Methods
7.1 Tests shall be conducted in accordance with the following test methods. Test procedures not incorporated here and not
covered by ASTM test methods shall be mutually agreed upon between the interested parties.
7.1.1 Specific Gravity—Test Methods D153, Method B.
7.1.2 Oil Absorption—Test Method D281.
7.1.3 Hegman Grind—Test Method D1210.
7.1.4 Coarse Particles—Test Methods D185.
7.1.5 pH—Test Methods D1208.
7.1.6 Specific Resistance—Test Method D2448.
7.1.7 Moisture—Test Methods D280.
7.1.8 Chemical Analysis—Incorporated in this specification as Annex A1 and Annex A2.
7.1.9 Loss on Ignition—Incorporated in this specification as Annex A3.
8. Keywords
8.1 analytical; zinc; zinc phosphate
D6280 − 98 (2014)
ANNEXES
(Mandatory Information)
A1. TEST METHOD FOR DETERMINATION OF ZINC CONTENT FOR ZINC PHOSPHATE TYPE PIGMENTS
A1.1 Scope
A1.1.1 This test method covers the determination of the zinc content for zinc phosphate monohydrate, dihydrate, tetrahydrate, or
mixtures of these various crystal water content pigments.
A1.1.2 This standard does not purport to address all the safety concerns, if any, associated with its use. It is the responsibility of
whoever uses this standard to consult and establish the appropriate safety and health practices and determine the applicability of
regulatory limitations prior to use.
A1.2 Reference Documents
A1.2.1 ASTM Standards: Test Method for Determination of Loss on Ignition for Zinc Phosphate Type Pigments
D1193 Specification for Reagent Water
A1.3 Summary of Test Method
A1.3.1 A weighed sample taken from Annex A3, Test Method for Determination of Loss on Ignition for Zinc Phosphate Type
Pigments completed analysis (that is, sample contains no associated crystal water), is dissolved in ammonia buffer, complexed with
disodium ethylendiaminetetraacetate dihydrate (EDTA) and back titrated with a standard zinc solution to an eriochrome black T
endpoint where the percent ZnO is determined.
A1.4 Significance and Use
A1.4.1 This test method provides a reliable means for determination of the percent ZnO for zinc phosphate pigments. The percent
ZnO content for the product gives evidence of the chemical purity of the pigment.
A1.5 Reagents and Materials
A1.5.1 Purity of Reagents—Reagent grade chemicals shall be used in this test, unless otherwise indicated. It is intended that all
reagents shall conform to the specifications of the Committee on Analytical Reagents of the American Chemical Society, where
such specifications are available. Other grades may be used, provided it is first ascertained that the reagent is of sufficiently high
purity to permit its use, without lessening the accuracy of the determination.
A1.5.2 Purity of Water—Unless otherwise indicated, references to water shall be understood to mean Type II of Specification
D1193.
A1.5.3 Buffer Solution (pH 10)—350 ml of concentrated NH OH + NH Cl and H O to give 1000 mL.
4 4 2
A1.5.4 Eriochrome Black T Indicator (0.5 %)—0.25 g eriochrome Black T + 2.2 g hydroxylamine hydrochloride per 50 mL
methanol.
A1.5.5 Primary Standard Zinc Oxide (0.2 N solution)—Accurately weigh 4.0690 g of oven dried ZnO. Dissolve in 250 mL of the
buffer solution and dilute to 500 mL. (Conversely, you can weigh up approximately 4.0 g of ZnO, create the solution, and
standardize it using the primary standard grade ZnO.)
D6280 − 98 (2014)
A1.5.6 0.2 N Disodium Ethylendiaminetetraacetate Dihydrate (EDTA)—37.2 g of EDTA per litre of aqueous solution.
A1.6 Procedure
A1.6.1 Weigh
...