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1、INTERNATIONAL STANDARD IS0 8781-I First edition 1990-l 1-15 p-a -_ -;-;I:y-z -., : -is S b) preparation of reduced pastes from each of these dispersions; c) determination of the rate of development of the tinting strength as a function of the amount of work done (this latter is related to the in- cr
2、emental stages of dispersion). The rate of development of tinting strength is assessed either by calcu- lating the percentage increase between two stages of dispersion or graphically. . . . III Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=N
3、ASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:02:28 MDTNo reproduction or networking permitted without license from IHS -,-,- INTERNATIONAL STANDARD IS0 8781-1:1990(E) Pigments and extenders - Methods of assessment of dispersion characteristics - Part 1: Assessment from the chan
4、ge in tinting strength of coloured pigments 1 Scope This part of IS0 8781 specifies a method for assess- ing, on the basis of tinting strength, the dispersion characteristics of coloured pigments which have been dispersed by one of the methods described in IS0 8780. It should be read in conjunction
5、with IS0 8780-I. The method is of general use for comparing similar pigments, for example a test pigment against an agreed reference pigment. 2 Normative references The following standards contain provisions which, through reference in this text, constitute provisions of this part of IS0 8781. At th
6、e time of publication, the editions indicated were valid. All standards are subject to revision, and parties to agreements based on this part of IS0 8781 are encouraged to investi- gate the possibility of applying the most recent edi- tions of the standards indicated below. Members of IEC and IS0 ma
7、intain registers of currently valid International Standards. IS0 105-A01:1989, Textiles - Tesfs for cotour fasf- ness - Part AOI: General principles of fesfing. IS0 591:1977, Titanium dioxide pigments for paints. IS0 787-24:1985, General methods of fest for pig- ments and extenders - Part 24: Deferm
8、inafion of relative tinting strength of coloured pigments and relative scattering power of white pigments - Photometric methods. IS0 8780-1:1990, Pigmenfs and exfenders - Methods of dispersion for assessment of dispersion charac- teristics - Part 1: Introduction. IS0 8780-2:1990, Pigmenfs and extend
9、ers - Methods of dispersion for assessmenf of dispersion charac- teristics - Parf 2: Dispersion using an oscitlafory shaking machine. IS0 8780-3:1990, Pigmenfs and extenders - Methods of dispersion for assessment of dispersion charac- teristics - Part 3: Dispersion using a high-speed impeller mitt.
10、IS0 8780-4:1990, Pigments and extenders - Methods of dispersion for assessment of dispersion charac- teristics - Part 4: Dispersion using a bead mitt. IS0 8780-5:1990, Pigments and exfenders - Methods of dispersion for assessment of dispersion charac- teristics - Part 5: Dispersion using an automati
11、c multer. IS0 87806:1990. Pigments and extenders - Methods of dispersion for assessment of dispersion charac- ferisfics - Part 6: Dispersion using a triple-roll mitt. 3 Definitions For the purposes of this part of IS0 8781, the follow- ing definitions apply, plus the definitions given in IS0 8780-I.
12、 3.1 coloured pigment paste: A dispersion of a col- oured pigment in a binder system. 3.2 white pigment paste: A dispersion of a white pigment in a binder system. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/99725
13、45001 Not for Resale, 04/25/2007 02:02:28 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 8781-1:1990(E) 3.3 reduced paste (reduction paste): A paste re- sulting from mixing a coloured pigment paste (3.1) with a white pigment paste (3.2). 4 Principle The pigment under t
14、est and, if provided, the agreed reference pigment are each dispersed in stages un- der specified conditions in an agreed binder system. After each incremental dispersion stage, a portion of the mill base is taken and mixed separately with a white pigment paste to form a reduced paste. The tinting s
15、trength (K/S value) of each reduced paste is determined as described in IS0 787-24. The percentage increase in tinting strength between two dispersion stages is calculated in order to assess the ease of dispersion of the pigment. Alternatively, a graph of the development of the tinting strength may
16、be prepared. 5 Required supplementary information For any particular application, the test method specified in this part of IS0 8781 needs to be com- pleted by supplementary information. The items of supplementary information are given in annex A. 6 Materials 6.1 White pigment The type of white pigm
17、ent used shall be agreed be- tween the interested parties, and shall be compat- ible with the binder system used in the preparation of the coloured pigment paste. Unless otherwise agreed, titanium dioxide, grade R2, complying with the requirements of IS0 591 shall be used. 6.2 White pigment paste Pr
18、epare the paste by dispersing the white pigment (6.1) in the binder system agreed for the dispersion of the test pigment. The pigment concentration shall be agreed. NOTE 1 For low-viscosity pastes, a suitable dispersion may contain about 20 % of titanium dioxide. For high- viscosity pastes, a suitab
19、le paste may contain about 40 % of titanium dioxide (see, for example, the paste specified in sub-clause 5.1 of IS0 787-24:1985). 7 Apparatus Ordinary laboratory apparatus and glassware, to- gether with the following: 7.1 Balance, capable of weighing to 0,l mg. 7.2 Film applicator, to give films of
20、adequate thick- ness from the reduced paste (see 8.2). 7.3 Substrates, for application of the reduced paste. Coated cards or glass plates have been found to be suitable. 7.4 Black and white contrast charts, for checking that an adequate film thickness of the reduced paste has been applied (see 8.2).
21、 7.5 Automatic mullet-, for preparation of the re- duced paste when using a high-viscosity binder system, or beaker, of glass or polyethylene, for preparation of the reduced paste when using a low- viscosity binder system. 7.6 Spectrometer, capable of measuring at wave- lengths between 400 nm and 70
22、0 nm, or photometer, with filters appropriate to the pigment under test, or tristlmulus calorimeter. 7.7 Cardboard template, of approximately 0,5 mm to 0,8 mm thickness, with a circular hole of the same diameter as the photometer (see 7.6) port, for use in measurements on wet films. 6 Procedure 8.1
23、Preparation of the reduced paste 8.1.1 Select an appropriate procedure from IS0 8780 to prepare the pigment dispersion. Take test portions of the coloured pigment paste at the chosen dispersion stages (see 10.1). 8.1.2 Take suitable amounts of the coloured pigment paste and white pigment paste (6.2)
24、, weigh to an accuracy of 0,5 % or better, and mix to provide a reduced paste of suitable depth of shade (see note 2). Mix in accordance with the appropriate pro- cedure described in 8.1.3. NOTE 2 A suitable reference depth of shade would be between II3 and l/25 of the reference depths for textiles
25、(see I.90 105A01:1989, clause 12) (e.g. reflectance or reflectance factor between 15 % and 50 %). 8.1.3 Use one of the following procedures, as ap- propriate. a) With a low-viscosity paste, mix the coloured pigment paste and the white pigment paste in the beaker (see 7.5) by stirring with a glass ro
26、d or a spatula until the mixture is homogeneous. En- sure that the mixing is thorough and carried out in a uniform manner, avoiding excessive shear 2 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for
27、 Resale, 04/25/2007 02:02:28 MDTNo reproduction or networking permitted without license from IHS -,-,- and periodically returning material adhering to the slirrer to the bulk of the mixture. b) With a high-viscosity paste, mix the coloured pigment paste and the white pigment paste using the automati
28、c muller (see 7.5) without application of a load on the upper plate. Place the weighed arnounts of the coloured pigment paste and white pigment paste on to the lower plate of the auto- matic muller (see note 3). Mix together using the minimum effort, with the aid of the spatula. Dis- tribute the pas
29、te at several points at a distance of about 35 mm from the centre of the lower plate or spread it in the form of a ring with an internal diameter of 40 mm and an external diameter of 100 mm (see note 4). After the top plate has been fitted, with no load applied, mix in four stages of 25 revolutions
30、each. After each stage, homogenize the mixture with the spatula and spread it as before. Do not mix pastes of high viscosity with pastes of low viscosity. NOTE 3 It is recommended that pigment pastes be weighed on a transparent plastics sheet. The bulk of the paste is then transferred with a spatula
31、 to the lower plate and the remainder can be scraped off the sheet on to the upper plate. NOTE 4 It is advisable to lay a paper ring of the requi- site shape as a pattern beneath the glass plate. 8.1.4 Prepare a reduced paste with the agreed ref- erence pigment following the same procedure. 8.2 Asse
32、ssment of the reduced paste Carry out an initial test by applying reduced paste to a contrast chart (7.4) to determine visually the minimum thickness required to give complete hid- ing. Then, using the film applicator (7.2), apply at least the minimum thickness of the reduced pastes of the test samp
33、le and the agreed reference pigment in quick succession on separate substrates (7.3) to give wet films of uniform thickness. A wet-film thickness of more than about 100 pm incurs the risk of floating and flooding. Thus, to minimize separ- ation, if an opaque film is not obtained with a wet- film thi
34、ckness of 100 pm, a second and, if necessary, a third film shall be applied after the first has dried. When the film starts to get tacky, carry out the fol- lowing rub-out tesl. (see note 5). Lightly rub part of each film with a finger. Compare visually the differ- ence in depth of shade between the
35、 rubbed and the non-rubbed surfaces (see note 6). If specified, allow the film to dry in accordance with the agreed or specified conditions. Otherwise con- tinue as described in clause 9. Carry out the photo- metric measurements (see clause 9) on reduced pastes that have been prepared consecutively
36、within IS0 8781-1 :1990(E) the same test series (i.e. those having approxi- mately the same age). NOTE 5 The rub-out test determines whether any pigment separation (for example floating, flooding or flocculation) has occurred. NOTE 6 Application of the reduced paste by a high- shear technique (for e
37、xample, a spray gun or hypodermic syringe) can be expected to give a film that displays a lower rub-out effect than that obtained with a film applied using a bar applicator. 9 Photometric measurement Measure the reflectivity or the reflectance factor of the non-rubbed surfaces of the films by the pr
38、o- cedure described in sub-clause 8.1.4 of IS0 787-24:1985. If a spectrometer is used, vary the wavelength of the light between 400 nm and 700 nm until a minimum value of poo or R, is obtained and measure at this wavelength. If a filter photometer or tristimulus photometer is used, select a filter t
39、hat restricts the measurements to wavelengths close to that of maximum absorption. Within one set of comparative tests, use the same wavelength or filter, selected on the basis of the maximum level of dispersion of the agreed refer- ence pigment reduction paste. Record the values of poo or R,. From
40、the measured values, obtain the corresponding values of K/S as given in IS0 787-24:1985, annex 6. NOTE 7 In certain cases, for example for information purposes, it could be of interest to make photometric measurements of the rubbed surface. This should be agreed between the interested parties. IO Ex
41、pression of results In this clause, ti is the quantity which represents the work done in the dispersion up to the end of stage i. It may be expressed in terms of time, the number of revolutions of a dispersion device, the number of passes through a triple-roll mill or simply the num- ber of stages.
42、10.1 Increase in tinting strength Choose two agreed dispersion stages 1 and 2, with stage 2 near the ultimate tinting strength. Calculate the increase in tinting strength between these two stages to the nearest whole number, using the equation where 3 Copyright International Organization for Standar
43、dization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/25/2007 02:02:28 MDTNo reproduction or networking permitted without license from IHS -,-,- IS0 8781-1:1990(E) IS is the increase in tinting strength, ex- pressed as a percentage; (K/S),
44、is the K/S value at the end of stage 1; If the range of IS values is between 50 and 100, a difference of greater than 12 shall be regarded as significant. (K/S)* is the K/S value at the end of stage 2 12 Test report When comparing the increase in tinting strength of different pigments, the same stag
45、es 1 and 2 should be used. These stages shall be stated in the test report. The test report shall contain at least the following information: 4 all details necessary to identify the product tested; 10.2 Tinting strength develapment graph Plot the K/S values obtained in accordance with clause 9 as a
46、function of ti. NOTE 8 A tinting strength development graph is useful for detailed assessment of ease of dispersion, particularly if a pigment has not yet been tested in this respect. For example, if the tinting strength development graph passes through a maximum (or the plot of the reciprocals of K
47、/S and li passes through a minimum), overgrinding, flocculation or recrystallization has occurred. A plot of the reciprocals is preferable as it yields an approximately straight line. Extrapolation of the line to l/fi = 0 (fi = 00) allows the ultimate tinting strength to be determined. Easy dispersi
48、on is indicated by a shallow slope, difficult dispersion by a steep slope (i.e. a large increase in tinting strength). 11 Significance of results If the increase in tinting strength IS is between 0 and 20, the difference in dispersibility between the test sample and the agreed reference pigment cann
49、ot be considered to be significant unless it is greater than 7. b) cl 4 4 9 9) h) a reference to this part of IS0 8781 and the rele- vant part of IS0 8780; the items of supplementary information referred to in annex A; whether wet or dry films were measured (see. 8.2 and clause 9); the increase in tinting strength IS and identifi- cation of the stages corresponding to (K/S), and (K/S)* (see lO.l), together with a statement whethe