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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
14、ds on the wetting properties of the binder system for the pigment being tested. NOTE 4 It may be preferable to operate the laboratory mill under non-ideal conditions so that differences be- tween pigments are exaggerated. It has been found in practice that, with well-formulated mill bases, differenc
15、es between easily dispersible pigments are minimized so that this test method is insensitive. Lower the impeller into the vessel to the agreed depth. Adjust the speed of rotation to that agreed. Confirm, from the flow pattern, that the mill base composition is satisfactory (see 7.2). If the flow pat
16、- tern is unsatisfactory, adjust the amount of pigment or binder system in the vessel until the flow pattern is correct and then, using the revised proportions, repeat the procedure from 8.1. Take test portions of the mill base after each of several (agreed) stirring times as follows: Stop the impel
17、ler after each of a number of agreed stirring times (for example 4 min, 8 min, 16 min, 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 19:18:36 MDTNo reproduction or networking
18、 permitted without license from IHS -,-,- IS0 8780-3:1990(E) 32 min) and take a small test portion. Measure the temperature of the mill base and adjust to an agreed temperature before re-starting the impeller. NOTE 5 The method described can also be adopted as a pre-mix procedure for mill bases that
19、 have to be further dispersed by a laboratory bead mill in accordance with IS0 8780-4. 8.4 Stabilization If necessary, for example if the mill base is not sta- ble enough, stabilize each test portion after its re- moval from the mill base by adding, for example, more binder and/or special additives.
20、 The procedure shall be agreed on between the interested parties. 8.5 De-aeration If necessary, allow any air bubbles within the test portions to escape before proceeding to assess the dispersion. The means by which this is achieved, for example by allowing to stand for a few minutes, shall be agree
21、d on between the interested parties. 9 Test report The test report shall contain at least the following information: 4 b) cl d) e) all details necessary to identify the product tested; a reference to this part of IS0 8780; the items of supplementary information referred to in annex A; any deviation
22、from the procedure specified; the date(s) of the test. 4 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 19:18:36 MDTNo reproduction or networking permitted without license from
23、IHS -,-,- IS0 8780-3:1990(E) Annex A (normative) Required supplementary information The items of supplementary information listed in this annex shall be supplied as appropriate to enable the method to be carried out. The information required should preferably be agreed between the interested parties
24、 and may be derived, in part or totally, from an international or national standard or other document related to the product under test. b) 4 4 e) a) Type and complete details of the impeller mill r) (see 4.1). Binder system (see clause 5). Composition of the mill base (see 7.1) and its temperature
25、(see 8.3). Stirring times (see 8.3). Stabilization procedure (see 8.4). De-aeration procedure (see 8.5). 5 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 19:18:36 MDTNo reproduc
26、tion or networking permitted without license from IHS -,-,- IS0 8780-3:1990(E) - - UDC 667.622:541.16.052:542.22 Descriptors: paints, pigments, extenders, dispersibility, dispersing Price based on 5 pages Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/26/2007 19:18:36 MDTNo reproduction or networking permitted without license from IHS -,-,-