ISO-8780-3-1990.pdf
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1、INTERNATIONAL STANDARD IS0 878003 First edition 1990-l I-15 ANSI hternat Dot Set Pigments and extenders - Methods of dispersion for assessment of dispersion characteristics - Part 3: Dispersion using a high-speed impeller mill Pigments et mati is the rotational frequency, in revolutions per minute,
2、of the impeller shaft; L _I lb-Q-J I,30 to 30 A a cv 0 z Ln 0 1 Figure 1 - Schematic section of a serrated-disc impeller mill 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 19
3、:18:36 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 8780-3:1990(E) The type and diameter of the disc, the geometry of the vessel and the speed of the disc shall be agreed on and recorded in the test report. NOTE 2 A vessel with a double wall to allow circulation of a
4、 liquid to control the temperature is recommended, and a lid with a central aperture may also be provided. NOTE 3 The diameter of a vessel used in an industrial- scale mill is normally two to three times the diameter of the impeller, or sometimes even greater. The vessel/disc geometry and the disc s
5、peed specified in this part of IS0 8780 make allowance for the small diameter of a lab- oratory disc. 4.2 Spatula. 5 Binder system The binder system shall be agreed on between the interested parties. The test repot-t shall state the binder, the solvent and the concentration of the binder in the solv
6、ent, as well as giving information on the rheological properties (for example viscosity or flow time) of the binder system. The same batch of binder system shall be used for all tests in the same series. 6 Sampling 7.2 Determination of mill base composition Add sufficient binder system to cover the
7、impeller. Start the motor at the lowest speed. Make small additions of pigment and gradually increase the speed to that agreed. Observe the flow pattern throughout the whole operation and note how much pigment has been added when a toroid is first formed. Continue to add pigment until the toroid sta
8、rts to collapse and again note the pigment mass added. Select a pigment concentration between these two points. 8 Procedure 8.1 Preliminaries Weigh the pre-determined amount (see 7.2) of the binder system into the vessel. Weigh the pre- determined amount (see 7.2) of the pigment into a separate cont
9、ainer. If the criterion for assessing the dispersion charac- teristics is to be the evaluation of the development of tinting strength (see IS0 8781-l), the masses of the pigment and of the binder system shall be de- termined to within 0,5 %. For other methods of as- sessment (for example fineness of
10、 grind, see IS0 8781-2, and change of gloss, see IS0 8781-3), wider tolerance ranges may be agreed on. 8.2 Pre-mixing Take a representative sample of the product to be tested, as described in IS0 842. If appropriate, bring the vessel and the binder sys- tern to the agreed temperature (see 8.3). Imme
11、rse the impeller to the agreed depth (see 4.1.2). 7 Mill base composition 7.1 General requirements With the impeller running at a low speed, gradually incorporate the pigment within a period of 5 min. Add the pigment at such a rate that a small amount of unwetted pigment always remains visible on th
12、e surface. Stop the motor, raise the impeller and, us- ing a spatula (4.2), scrape off any pigment adhering It is essential that the mill base assumes a flow pattern in the form of a toroid (or doughnut). The concentrations of pigment and binder system re- quired to give this pattern shall be determ
13、ined by to the impeller shaft and walls of the vessel into the mill base. 8.3 Dispersion prior experiment. In order to develop high shear in the mill, a high- viscosity mill base is desirable. Thus, high pigment loadings and/or high binder-solids are usually re- commended. The best combination depen
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