Conferences

Citation

(2009), "Conferences", Pigment & Resin Technology, Vol. 38 No. 6. https://doi.org/10.1108/prt.2009.12938fac.002

Conferences

Article Type: Conferences, training and publications From: Pigment & Resin Technology, Volume 38, Issue 6

Predicting the service life of organic coatings “options and constraints”

1 day Symposium, January 21, 2009

Paper 1

Strategic options for service life prediction – an overview

Jon Graystone

PRA

Within the Coatings Industry estimates of durability or service life are often made by a relative comparison with products that have an established performance profile. Ideally however a lifetime prediction is quantified in chronological terms but with many caveats as to how this can be expressed. Coatings are expected to maintain both appearance and protective functions which are subjected to many environmental factors.

Premature catastrophic failure is clearly undesirable but most failure is of a more gradual nature with stochastic elements. Defining a clear “end-of-life” condition is seldom possible and results must usually be expressed in statistical terms. The performance of coatings formulation is significantly modified by external factors including the substrate, application conditions and design aspects of the structures or objects to which they are applied. Criteria for failure are significantly different between the Architectural and various Industrial market sectors.

Strategic decisions for service life prediction (SLP) must thus start with clear objectives in order for the merits of different methodologies to be properly assessed. The choice of methodologies is broad with both probabilistic and deterministic options. Arguably durability is best established by real-time exposure in the actual location and circumstances where the coating is to be deployed. Such an approach is expensive and time consuming consequently there is a wide gamut of alternatives. These range from exposure under more severe but still “natural” conditions to various accelerating devices and test methods. Overlaid upon this is the question of what to measure; it could be a customer perceived performance factor, or a correlating mechanical property or a more fundamental investigation of the chemistries involved using the full range of modern analytical equipment.

Both the experimental design and data handling will be influenced by the methodology chosen. Descriptive and Scientific methodologies have been described with several variants. Data analysis of the results may deploy established mathematical techniques including regression analysis and non- parametric statistics. Other options include times series analysis and reliability methodologies. Inasmuch that there is much prior knowledge about durability some consideration should also be given to Bayesian methods. Ultimately the information gained should be succinctly expressed in the form of a predictive model which might be purely phenomenological, but ideally based on deterministic principles that can be validated, and provide a direct link between laboratory and field experience.

Paper 2

Predicting the service life of infrastructure materials: a case study

Jonathan Martin

National Institute of Standards & Technology

Paper 3

Spectroscopic studies of degradation in coil coating polyester in the real world and on accelerated testing

James Maxted and Dr Wanrui Zhang

Becker Industrial Coatings

Considerable efforts have been made in the last decade to better characterise the chemical as well as the macro changes in weathered coatings. A variety of spectroscopic techniques have been utilised to compare what happens in a raft of accelerated weathering tests with a well-characterised environment like Florida. A further challenge now presents itself to the coatings formulator with the globalisation of many industries such as coil coating of metal sheeting. As proven technologies are transferred and used in different parts of the globe, how can we be sure that they will perform well in as yet untried environments? Can the performance in Florida or Europe be used to predict the coating's performance in equally demanding (sometimes more demanding) environments elsewhere?

This paper will describe the strategy that Becker has adopted to meet this challenge. An intensive study of how macro property changes in polyester melamine coil coatings correlate in a range of global environments and accelerated tests, has confirmed that different locations impart different emphasis onto the well-known agents of degradation: water, UV, and temperature. Techniques such as continuous and step scan PAS FTIR and Confocal Ramen spectroscopy have been used to better establish the link between these macro changes in the surface and bulk chemistry of the binders and also the impact of pigment chemistry to the overall degradation of appearance in different global locations. Only when the relative importance of individual stresses and their impact on the different components of the formulations are better understood, can coatings be properly formulated to meet local performance demands, at suitable cost, in a rapid and reliable manner.

Paper 4

Service life prediction of wood claddings by in-situ measurement of wood moisture content: ongoing research: status after approximately, 5 years of outdoor weathering

Berit Lindegaard

Danish Technological Institute

The Danish Technological Institute is in co-operation with industry partners running a project aiming at predicting the service life of different wood protecting systems.

The project focuses on examining the moisture reducing effect of different protecting systems for timber claddings and the ability to maintain the appearance of the surfaces, when the wood is used in service class 3.

The examination comprises different types of coating treatments (e.g. non-permeable and permeable and solvent and water-borne types) and wood species. Different mathematical models are used to indicate the service life of the different test systems.

A façade construction is exposed to weathering at the field test area of the Danish Technological Institute (near Copenhagen). In specific locations of the construction measurements of wood moisture is done by in situ resistance moisture meters. Once a year the surface is subject to evaluation in relation to appearance, mould growth and degradation. A total of 60 test façade are now exposed. This paper will primarily focusing on treatments on Scots pine sapwood.

Paper 5

Experimental and methodology research to predict service life of organic coatings for ETICS and masonry

Sonia Lupica Spagnolo

Milan Polytechnic

Paper 6

Automotive xenon arc test methods: a correlation study

Jim Regan

Q-Lab

Don Vesey, Rick Luxgrandt

Chrysler

Lynn Pattison

BASF

Ronald Roberts, Jeffrey Quill

Q-Lab

The Society of Automotive Engineers (SAE) has recently approved two new performance-based weathering test methods to replace the older hardware-based methods. The new methods describe the exposure conditions and control tolerances rather than describing a specific hardware configuration. The publication of these new test methods was the result of years of development by the Automotive Materials Association and the SAE.

The new test methods SAE J2527 and J2412 are the performance based replacements for SAE J1960 and J1885, respectively. They do not include new test conditions. Instead, they remove all references to old outdated hardware, replacing them with clear definitions of the desired operating conditions.

Hardware based test methods limit the selection of testers. This results in severely limited technological advancements. The new performance based test standards now allow users of these test standards the ability to use the most modern, most accurate, cost most effective equipment available.

This paper reports on a cooperative research program conducted by Chrysler, BASF Corporation and Q-Lab Corporation. The goal of the research was to test the performance of the new performance-based test methods and to qualify newer xenon arc test equipment for use in automotive testing. Specifically, the research compared the results of test exposures conducted in the old-style rotating drum style testers mandated in J1960 and J1885 to exposures performed in the newer testers, covered by J2412 and J2527.

Paper 7

In situ, in vitro and in silico analysis of coating performance

Dr Jan Van den Bulcke, Doris Van Acker and Marc Stevens

Ghent University

SLP is a complex yet essential method for analysing coating performance. Accurate and precise assessment is crucial for a strong position on the market. Correct knowledge of the critical failure points, maintenance/replacement frequency and related costs are part of this approach. This paper describes the scale-dependent tools within a bio-engineering framework that are applied for coating research, ranging from modelling, X-ray tomography, lab testing, controlled fungal infestation up to continuous moisture set-ups and large-scale window frame weathering.

Paper 8

Contribution of the methanistic approach to the improved reliability of accelerated weathering tests and service life prediction

Dr Olivier Haillant

Atlas Material Testing Technology

Most of today's activity in the fields of material weathering and SLP is still proceeding from more or less empirical approaches that rely on the simulation approach developed in 1950s, where the chemical nature of the materials could not be considered.

With the improvement of analytical techniques, a more rational approach was developed in 1970s, based on the detailed analysis of the chemical evolutions of aging materials. This so-called “mechanistic” approach is gaining more and more acceptance in the plastic industry, as proven by the recent ISO Technical Committee 61 approval to promote this methodology to the status of international standard. Additionally to providing tools for estimating the change in functional properties of materials from a careful assessment of chemical evolutions, this methodology enables to check whether an accelerated test method reproduces the main degradation pathways as observed in the real life of the material.

9. Open Forum

Meeting the needs of the Coating Industry

Discussion Chaired by Peter Collins (PRA)

Scope:

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  methodologies and techniques;

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  substrate specifics;

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  education and training;

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  equipment; and

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  standards.

10. Wrap-up session

For further information, contact: PRA web site: www.pra.org.uk/conferences/servicelifeprediction/programme.htm