ASTM_D_4217_-_07_2013.pdf

Designation:D421707(Reapproved 2013)Standard Test Method forGel Time of Thermosetting Coating Powder1This standard is issued under the fixed designation D4217;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method determines the length of time athermosetting coating powder takes to gel on a polished metalsurface at a specified temperature,such as 204C(400F).Thedetermination of the gel time is a very simple method for thecharacterization and quality control of coating powders.However,the gel time determined by this method is notdirectly related to the time for the coating powder to cure inpractical applications.1.2 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ISO Standards:ISO 81306:1992 Coating powdersPart 6:Determinationof gel time of thermosetting coating powders at a giventemperature23.Terminology3.1 Definitions:3.1.1 coating powder,nfinely divided particles of resin,either thermoplastic or thermosetting,generally incorporatingpigments,fillers,and additives and remaining finely dividedduring storage under suitable conditions,which,after fusingand possibly curing,give a continuous film.3.1.2 cure time of a coating powderthe time required fora thermosetting coating powder to sufficiently chemicallycrosslink at a given temperature to provide the required coatingproperties.3.1.3 gel time of a coating powderthe interval required ata given temperature for a coating powder to be transformedfrom a dry solid to a gel-like state.3.1.4 powder coating,ncoatings which are protective ordecorative,or both,formed by the application of a coatingpowder to a substrate and fused in a continuous film by theapplication of heat or radiant energy.3.1.5 thermosetting,adjdescribing a material that,whenheated per a minimum recommended cure condition,under-goes a chemical reaction and a permanent change to a moredurable state capable of specific properties as designed forsubstrate protection or decoration,or both.4.Significance and Use4.1 This test method is useful for selecting coating powdersthat gel in the desired time at the specified temperature.Themethod is not useful for determination of cure time.5.Apparatus5.1 Hot Plate,3having an electrically heated metal blockwith a polished surface capable of being maintained at tem-peratures between range 130 to 230C(266 to 466F)to within62C(64F).The temperature should be controlled by meansof a thermoregulator.NOTE1There are expected differences in results between this methodand ISO 81306 which requires a heating block with small depressions.5.2 Stopwatch or Timer,accurate to at least 1 s.5.3Stirrer,of very low heat capacity and of suitable size.Wooden stirrers with dimensions of 2 mm by 6 mm by 130 mmor(116in.by14in.by 5 in.)have been found suitable.5.4 Surface Contact Thermocouple,suitable for use at 150to 250C(300 to 480F)and reading no greater than 1C(2F).5.5 Measuring Spoon,of 1.25 cc(14tsp)capacity.5.6 Scraper,made of material softer than that of the heatingblock,for removing the test material from the heating blockwithout scratching its surface.6.Selection of Specimens6.1 Obtain a representative sample of the coating powder.1This test method is under the jurisdiction of ASTM Committee D01 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.51 on Powder Coatings.Current edition approved June 1,2013.Published July 2013.Originally approvedin 1982.Last previous edition approved in 2007 as D4217 07.DOI:10.1520/D4217-07R13.2Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.3The sole source of supply of the Model SS-200 hot plate known to thecommittee at this time is Thermo-Electric Co.,455 Route 30,Imperial,PA 15126.If you are aware of alternative suppliers,please provide this information to ASTMInternational Headquarters.Your comments will receive careful consideration at ameeting of the responsible technical committee,1which you may attend.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 6.2 Store the sample of coating powder in accordance withthe manufacturers recommendations,after sampling and priorto testing.6.3 A specimen shall consist of approximately 1.25 ml(14tsp)of coating powder.7.Procedure7.1 Place the hot plate in a draft-free location or use athree-sided draft shield constructed to eliminate drafts.7.2 Allo