ASTM_D_6619_-_00_2016.pdf

Designation:D661900(Reapproved 2016)Standard Practice forIncorporating Pigments by High Speed Dispersion1This standard is issued under the fixed designation D6619;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.Scope1.1 This practice covers the dispersion of pigments using alaboratory size high-speed impeller mill.It is similar intechnical content to ISO 8780-3.NOTE1This practice is restricted to mill bases of moderately highviscosity due to either high vehicle concentration or high pigmentconcentration,or both,which can produce high shear force.It is notintended to provide a means of formulating either pilot plant or full-scalemill base compositions(scaling up the process from laboratory equipmentto factory mills is not simple).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 8780-3 Pigments and ExtendersMethods of Disper-sion for Assessment of Dispersion CharacteristicsDispersion Using a High Speed Impeller Mill23.Significance and Use3.1 High speed dispersion is a commonly used dispersionmethod in the coatings industry.For the purpose of thispractice,“high speed”would normally be understood to be arange of RPM between 3 000 and 10 000.This practiceprovides a reference for its use,so that a producer and user canstandardize on an incorporation technique.This will minimizedifferences in the millbase,and allow the interested parties toconcentrate on the physical,chemical,or optical methods to berun.4.Apparatus4.1 High-speed Impeller Mill,consisting of a cylindricalvessel and a horizontal disk stirrer blade driven by a motor.Adisk with a serrated edge is commonly used.4.1.1 Drive UnitThe power rating of the drive unit shallbe sufficient to maintain the peripheral speed of the disk at anagreed value.A reduced rotational speed shall be available forpre-mixing in accordance with 6.2.The motor of the drive unitshall be mounted on a stand together with the impeller shaft sothat its height can be adjusted.There shall be a clamping devicefor the vessel at the foot of the stand,such that the impellershaft is concentric with the vessel.4.1.2 Disk and Vessel:4.1.2.1 The diameters of the vessel and the disk shall besuch that there is adequate clearance between the disk periph-ery and the walls of the vessel(see Fig.1).If the disk isserrated,it shall be mounted so that the direction of movementof the serrations is such that the mill base flows in thedirections shown in Fig.1.4.1.2.2 The degree of dispersion achieved will depend onthe type of disk used.Fig.1 shows only one type.4.1.2.3 The type and diameter of the disk,the geometry ofthe vessel,and the speed of the disk shall be agreed upon andrecorded in the test report.NOTE2A vessel with a double wall to allow circulation of a liquid tocontrol the temperature should be employed,if necessary.A lid with acentral aperture may also be provided.NOTE3The diameter of a vessel used in an industrial scale mill isnormally two to three times the diameter of the impeller,or sometimeseven greater.The vessel/disk geometry and the disk speed specified makeallowance for the small diameter of a laboratory disk.5.Vehicle System5.1 The vehicle system shall be agreed upon between theinterested parties.Agreement will be necessary on the vehicle,the solvent,the concentration of the vehicle in the solvent,aswell as any critical temperature sensitivity or rheologicalproperties(for example viscosity)of the vehicle system.Thesame batch of vehicle system shall be used for all tests in thesame series.6.Mill Base Composition6.1 General Requirements:6.1.1 It is essential that the mill base assume a pattern in theform of a toroid(or doughnut).The concentrations of pigmentand vehicle system required to give this pattern shall bedetermined by prior experiment.6.1.2 In order to develop high shear in the mill,a highviscosity mill base is desirable.Thus,high pigment loadings or1This practice is under the jurisdiction of ASTM Committee D01 on Paint andRelated Coatings,Materials,and Applications and is the direct responsibility ofSubcommittee D01.24 on Physical Properties of Liquid Paints and Paint Materials.Current edition approved Dec.1,2016.Published December 2016.Originallyapproved in 2000.Last previous edition approved in 2012 as D6619 00(2012).DOI:10.1520/D6619-00R16.2Available from American National Standards Institute(ANSI),25 W.43rd St.,4th Floor,New York,NY 10036,http:/www.ansi.org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United St