EN ISO 8780-3-1995 en Pigments and Extenders - Methods of Dispersion for Assessment of Dispersion Characteristics - Part 3 Dispersion Using a High-Speed Impeller Mill《颜料和体质颜料 评定分散性.pdf
《EN ISO 8780-3-1995 en Pigments and Extenders - Methods of Dispersion for Assessment of Dispersion Characteristics - Part 3 Dispersion Using a High-Speed Impeller Mill《颜料和体质颜料 评定分散性.pdf》由会员分享,可在线阅读,更多相关《EN ISO 8780-3-1995 en Pigments and Extenders - Methods of Dispersion for Assessment of Dispersion Characteristics - Part 3 Dispersion Using a High-Speed Impeller Mill《颜料和体质颜料 评定分散性.pdf(17页珍藏版)》请在麦多课文档分享上搜索。
1、A BRITISH STANDARD Pigments and extenders - Methods of dispersion for assessment of dispersion characteristics Part 3. Dispersion using a high-speed impeller mill The European Standard EN IS0 87803 : 1995 has the status of a British Standard . 3s EN IS0 17803 : 1995 National foreword . This Part of
2、BS 3483 has been prepared under the direction of the Pigments, Paints and Varnishes Standards Policy Committee. It is identical with IS0 8780-3 : 1990 Pigments and extenders - Methods of dispersion for assessment of dispersion characteristics - Part 3 : Dispersion using a high-speed impeller mill, p
3、ublished by the International Organization for Standardization (ISO) . In 1994 the European Commiaee for standardizatjon (CEN) accepted Is0 87803 : 1990 as European standard EN Is0 87803 : 1994. As a consequence of implementing the European Standatxi this British standard is renumbered as WEN Is0 87
4、80-3 and any reference to J3S 3483 : Part D3 is the rotational frequency, in revolutions per minute, of the impeller shaft; m 1,3 D to 30 -I Figure 1 - Schematic section of a serrated-disc impeller mill 2 STD-BSI BS EN IS0 8780-3-ENGL 1775 lb24bb7 b77570 7bb = IS0 8780-31990(E) The type and diameter
5、 of the disc, the geometry of the vessel and the speed of the disc shall be agreed on and recorded in lhe tecl report. NOTE 2 A vessel with a double wall to allow circulation of a liquid to control the temperature is recommended, and a lid with a central aperture may also be provided. NOTE 3 The dia
6、meter of a vessel used in an industrial- scale mill is normally two lo three times the diameter of the impeller, or sometimes even greater. The vesselldisc geometry and the disc speed specified in this part of IS0 0780 make allowance for the small diameter of a lab- oratory disc. 4.2 Spatula. 5 Bind
7、er system The binder system shall be agreed on between the interested parties. The test report shall state the binder, the solvent and the concentration of the binder in the solvent, as well as giving information on the rheological properties (for example viscosity or flow time) of the binder system
8、. 7.2 Determination of mill base composition Add sufficient binder system to cover the 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 ha
9、s been added when a toroid is first formed Continue to add pigment until the toroid starts to collapse and again note the pigmenl 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
10、 vessel. Weigh the pre- determined amount (see 7.2) of the pigment into a separate container. If the criterion for assessing the dispersion charac- teristics is to be the evaluation of the development of tinting strenglh (see IS0 8781-l), the masses of the pigment and of lhe binder system shall be d
11、e- termined to within 0,5%. For other methods of as- The same batch of binder system shall be used for sessment (for example fineness of grind, see all tests in the same series. IS0 8781-2. and change of gloss, see IS0 8781-3). wider tolerance ranges may be agreed on. 6 Sampling 8.2 Pre-mixing If ap
12、propriate, bring the vessel and the binder sys- tem to the agreed temperature (see 8.3). Immerse the impeller to the agreed depth (see 4.1.2). Take a represen1a1ive sample Of the product to be lested. as described in IS0 842. 7 Mill base composition With the impeller running at a low speed, graduall
13、y incorporate the pigment within a period of 5 min. Add the Diament at such a rate that a small amount of unwetted pigment always remains visible on the surface. Stop the motor, raise the impeller and, us- ing a spatula (4.2). scrape off any pigment adhering to the impeller shaft and walls of the ve
14、ssel into the mili base. 8.3 Dispersion 7.1 General requirements It is essential that the mill base assumes a flow pattern in the form of a toroid (or doughnut). The concentrations of pignient and binder system re- quired to give this pattern shall be determined by prior experiment. Lowei- ihe impel
15、ler into lhe vessel to lhe agreed 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 depends on the wetting properties of the binder system for the pigment being t
16、ested. NOTE 4 It may be preferable to operate the laboratory mill under non-ideal conditions so that differences be- tween pigments are exaggerated. lt has been found in practice that, with well-formulated mill bases, differences between easily dispersible pigments are minimized so that this test me
17、thod is insensitive. 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 now pat- lern is unsalisfaclory, adjust lhe amount of pigrnent or binder system in the vessel until the flow pattern is correct an
18、d then, using the revised proportions, repeal the procedure from 8.1. Take tecl portions of the mill base afer each of several (agreed) stirring times as follows: Stop the impeller after each of a niimber of agreed stirring times (for example 4 min. 8 min, 16 min. 3 STD-BSI BS EN IS0 8760-3-ENGL 197
19、5 LbZbb7 Ob77571 T2 IS0 8780-31990(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 have to be further di
20、spersed 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. The procedure shall b
21、e 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 kw minutes. shall be agreed on between the intere
22、sted parties. 9 Test report The test report shall contain at least the following information: . a) all details necessary to identify the product tested: b) a reference io this pari of IS0 8780; c) the items of supplementary inforniation referred to in annex A: d) any deviation rom the procedure spec
23、ified: e) the dale(c) o the test. 4 Annex A (normative) Required supplementary information ,i 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 interest
24、ed parties and may be derived, in part or totally, from an international or national standard or other document related to the product und er test. a) Type and complete details of the impeller mill b) Binder system (see clause 5). c) Composition of the mill base (see 7.1) and ils temperature (see 8.
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