Standard Test Method for Determination of Copper Release Rate From Antifouling Coatings in Substitute Ocean Water

Importancia y uso:

4.1 This test method is designed to provide a laboratory procedure to quantify and characterize the release rates of copper from antifouling coatings in substitute ocean water over a period of immersion under specified laboratory conditions of constant temperature, pH, salinity, and low copper concentration. Quantitative measurement of the release rate is necessary to help in selection of materials, in providing quality control, and in understanding the performance mechanism.

4.2 Results from this test method establish a pattern of copper release from an antifouling coating over a minimum of 45 days exposure under controlled laboratory conditions. Copper release rates from antifouling paints in-service vary over the life of the coating system depending on the formulation and on the physical and chemical properties of the environment. Factors such as differences in berthing locations, operating schedules, length of service, condition of paint film surface, temperature, pH, and salinity influence the actual release rate under environmental conditions. Results obtained using this test method do not reflect actual copper release rates that will occur in-service, but provide comparisons of the release rate of different antifouling formulations in substitute ocean water under the prescribed laboratory conditions.

4.3 By comparison with copper release rate measurements obtained either by direct measurements of copper release rate from AF coating systems on ship hulls, or copper release rate measurements from AF coating systems from harbor exposed panels, all available data indicate that the results of this test method (Test Method D6442) significantly overestimate the release rate of copper when compared to release rates under in-service conditions. Published results demonstrate that this test method produces higher measurements of copper release rate than from direct in-situ measurements for the same coating on in-service ship hulls and harbor-exposed panels. The difference between the results of this test method and the panel and ship studies was up to a factor of about 30 based on data for several commercial antifouling coatings.3, 4 Realistic estimates of the copper release from a ship's hull under in-service conditions can only be obtained from this test method where the difference between the results obtained by this test method and the release rate from an AF coating in-service is taken into account.

4.4 Where the results of this test method are used in the process of generating environmental risk assessments, for environmental loading estimates, or for regulatory purposes, it is most strongly recommended that the relationship between laboratory release rates and actual environment inputs is taken into account to allow a more accurate approximation of the copper release rate from antifouling coatings under real-life conditions. This can be accomplished through the application of appropriate correction factors.4

Subcomité:

D01.45

Referida por:

D6903-07R26

Volúmen:

06.02

Número ICS:

87.040 (Paints and varnishes)

Palabras clave:

antifouling coating; copper; release rate;