1、Designation: D 6619 00 (Reapproved 2006)Standard Practice forIncorporating Pigments by High Speed Dispersion1This standard is issued under the fixed designation D 6619; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st 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 practice covers the dispersion of pigments using alaboratory size high-speed impeller mill. It is similar intechni
3、cal content to ISO 8780-3.NOTE 1This 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-sca
4、lemill 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 an
5、d 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
6、.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
7、 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
8、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 unitsh
9、all 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 shal
10、l 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 dispe
11、rsion 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.NOTE 2A vessel with a double wall to allow circulation of a liquid tocont
12、rol the temperature should be employed, if necessary. A lid with acentral aperture may also be provided.NOTE 3The 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 sp
13、ecified 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 se
14、nsitivity 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 doughn
15、ut). The concentrations of pigmentand vehicle system required to give this pattern shall bedetermined by prior experiment.1This 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
16、 Physical Properties of Liquid Paints and Paint Materials.Current edition approved April 1, 2006. Published April 2006. Originallyapproved in 2000. Last previous edition approved in 2000 as D 6619 - 00.2Available from American National Standards Institute (ANSI), 25 W. 43rd St.,4th Floor, New York,
17、NY 10036.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.6.1.2 In order to develop high shear in the mill, a highviscosity mill base is desirable. Thus, high pigment loadings orhigh vehicle solids, or both are usually recommended. Th
18、e bestcombination of conditions depends upon the wetting propertiesof the vehicle system for the pigment being tested.NOTE 4It may be preferable to operate the laboratory mill undernonideal conditions so that differences between pigments are exaggerated.It has been found in practice that, with well-
19、formulated mill bases,differences between easily dispersible pigments are minimized so that thispractice is insensitive.6.2 Determination of Mill Base Composition:6.2.1 Add sufficient vehicle system to cover the impeller.Start the motor at the lowest speed. Make small additions ofpigment (standard o
20、r test sample) and gradually increase thespeed to that agreed. Observe the flow pattern throughout thewhole operation and note how much pigment has been addedwhen a toroid is first formed. Continue to add pigment until thetoroid starts to collapse, and again note the pigment massadded. Select a pigm
21、ent concentration between these twopoints.7. Procedure7.1 Preliminaries:7.1.1 Weigh the predetermined amount (see 6.2)ofthevehicle system into the vessel. Weigh the predeterminedamount (see 6.2) of the pigment (standard or test sample) intoa separate container.7.2 Pre-mixing:7.2.1 If appropriate, br
22、ing the vessel and the vehicle systemto the agreed temperature (see Section 5). Immerse the impellerto the agreed depth (see 4.1.2).7.2.2 With the impeller running at a low speed, graduallyincorporate the pigment within a period of 5 min. Add thepigment at such a rate that a small amount of unwetted
23、 pigmentalways remains visible on the surface of the millbase. Stop themotor, raise the impeller and, using a spatula, scrape off anypigment adhering to the impeller shaft and walls of the vesselinto the mill base.7.3 Dispersion:7.3.1 Lower the impeller into the vessel to the agreed depth.Adjust the
24、 speed of rotation to that agreed. Confirm from theflow pattern that the mill base composition is satisfactory (see6.1). If the flow pattern is unsatisfactory, adjust the amount ofpigment or vehicle system in the vessel until the flow pattern iscorrect, and then, using the revised proportions, repea
25、t theprocedure from 7.1.7.3.2 If desired, take test portions of the mill base after eachof several (agreed) milling times as follows:7.3.2.1 Stop the impeller after each of a number of agreedmilling times (for example 4 min, 8 min, 16 min, 32 min) andtake a small test portion. Measure the temperatur
26、e of the millbase, if specified, and adjust to an agreed temperature beforerestarting the impeller.7.4 Stabilization:7.4.1 If necessary, for example if the mill base is not stableenough, stabilize each test portion after its removal from themill base by adding, for example, more vehicle or specialad
27、ditives, or both. The procedure shall be agreed upon betweenthe interested parties.7.5 Deaeration:7.5.1 If necessary, allow any air bubbles within the testportions to escape before proceeding to assess the dispersion.The means by which this is achieved, for example by allowingto stand for a few minu
28、tes, shall be agreed upon between theinterested parties.8. Keywords8.1 high speed dispersionFIG. 1 Schematic Section of a Serrated-disk Impeller MillD 6619 00 (2006)2ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin thi
29、s standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be
30、 reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theresp
31、onsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, We
32、st Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).D 6619 00 (2006)3
