ASTM_D_4758_-_92_1998.pdf

Designation:D 4758 92(Reapproved 1998)Standard Test Method forNonvolatile Content of Latexes1This standard is issued under the fixed designation D 4758;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(e)indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers a quality control test fornonvolatile content of latex vehicles.The specified time-temperature conditions(180C,20 min)were selected to allowtest completion in 1 h or less.For latex vehicles used in certainair-dry or low-temperature bake coatings,as well as for thosethat contain temperature-sensitive materials,the use of a lowertemperature and other bake time will more accurately reflectthe effective nonvolatile content(Note 1).Alternative time-temperature conditions should be agreed upon between theproducer and user.NOTE1The test conditions of Test Method D 2369(110C,60 min)have been found suitable for use with many latex vehicles.1.2 This test method is not intended to be employed fordetermining the volatile organic content(VOC)of formulatedcoatings.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is responsi-bility of the user of this standard to consult and establishappropriate safety and health practices and determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:D 2369 Test Method for Volatile Content of Coatings2E 145 Specification for Gravity-Convection and Forced-Ventilation Ovens3E 300 Practice for Sampling Industrial Chemicals43.Significance and Use3.1 This test method is designed to quantify the weightpercent of a commercial,synthetic latex product that,whenincorporated into a coating product,constitutes the bindercontent of the applied coating.4.Apparatus4.1 Oven,forced-ventilation Type IIB,as specified in Speci-fication E 145,with closed vent.4.2 Balance,sensitive to 0.1 mg.4.3 Desiccator.4.4 Weighing dish,aluminum,approximately 57 mm indiameter by 18 m deep.4.5 Syringe,5-mL disposable.5.Sampling5.1 Procedures described in the Slurry Sampling section ofPractice E 300 shall be used for sampling latexes.6.Procedure6.1 For each latex to be tested,wash two aluminum disheswith a suitable reagent grade solvent(for example,toluene)orheat to constant weight to assure that volatile contaminants areremoved.Determine the tare weight of the aluminum dishes to0.1 mg.6.2 Thoroughly mix the sample on a mechanical shaker orcan roller to assure homogeneity.6.3 Draw 3.5 mL of the sample into the syringe and weighto 0.1 mg.6.4 Transfer 1.5 6 0.1 mL of the latex into a tared weighingdish and reweigh the syringe to 0.1 mg.Calculate the latexspecimen weight,S,as follows:S 5 w12 w2(1)where:w1=initial weight of syringe and latex,g,w2=weight of syringe and latex remaining after discharg-ing specimen,g.6.5 Repeat 6.4 for the duplicate determination.6.6 Transfer the aluminum dishes to an oven operating at180 6 4C and heat for 20.0 6 1 min.(Note 2).Remove fromthe oven,cool in a desiccator for 5 min at room temperatureand weigh to 0.1 mg.Determine the weight of residue,N,ineach dish as follows:N 5 W12 W2(2)where:W1=weight of dish and residue,g,W2=tare weight of aluminum dish,g.1This test method is under the jurisdiction of ASTM Committee D-1 on Paintand Related Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.33 on Polymers and Resins.Current edition approved May 15,1992.Published July 1992.Orginallypublished as D4758 88.Last previous edition D4758 88.2Annual Book of ASTM Standards,Vol 06.01.3Annual Book of ASTM Standards,Vol 14.02.4Annual book of ASTM Standards,Vol 15.05.1Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959,United States.NOTE2Add distilled water to viscous test specimen prior to baking.7.Calculation7.1 Calculate the mean weight percent nonvolatile material(%NVM)where Subscripts 1 and 2 refer to the individual datafrom the duplicate determinations:%NV 5N1/S11 N2/S223 100(3)8.Report8.1 Report the nonvolatile content to 0.01 weight%.9.Precision and Bias9.1 An interlaboratory study was conducted on this testmethod in which one operator in each of five laboratories madeduplicate determinations on each of two days on six commer-cial latices containing 44 and 65%nonvolatile matter.Thelatex polymer types were three all-acrylics,a vinyl acetate-acrylic copolymer,and acrylic terpolymer and a vinyl acetate-vinyl chloride-ethylene copolymer.Two laboratories could notrun the test on two latexes because they had gelled,and in thestatistical analysis all results obtained on one latex wererejected because they differed significantly from the others.The pooled within-laboratory standard deviation was found tobe 0.09%absolute with 20 degrees of freedom and thebetwee