1、National Standard of the Peoples Republic of ChinaDetermination of relative tinting strength of colored pigments and relative scattering power of white pigmentsPhotometric methods GB/T13451.2-92This standard adopts equivalently the ISO787/24-1985 General methods of test for pigments and extenders; P

2、art 24: Determination of relative tinting strength of colored pigments and relative scattering power of white pigmentsPhotometric methods.1. Content and application scope:This standard regulates the general test method using photometer to determine the 2 same pigments relative tinting power and 2 sa

3、me white pigments relative scattering power.When this general method is unfit for some specific products, then should regulate one special method to determine relative tinting strength and relative scattering power of white pigments.2. Reference standard;GB 5211.16 Comparison of lighting power of wh

4、ite pigmentsGB 5211.19 Determination of relative tinting strength and colour on reduction of coloured pigmentsvisual comparison method.GB 9285 Raw materials for paints and varnishesSampling3. Definition 3.1 Tinting strength: the ability of pigments to absorb income light, so it can have the ability,

5、 for example, let the added white coloue pigments colored or colour become dark. 3.2 Absorption index ： light absorption factor of the colored binder÷density of pigments Cm.Where: -spectral absorption factor, coloured pigments amount in material, unit to be expressed by the reciprocal of film.

6、of thickness unit. Cm.To express pigment density by using ratio of the quantity of pigment to binder.3.3 Relative tinting strength: the ratio of samples absorption index to standard samples absorption index , expressed by percentage.3.4 Scattering power: The power of pigment to scatter the income li

7、ght, so after adding such pigment, the color paint has the ability of opaque and light.3.5 Scattering Index ：the spectral scattering factor÷pigment density Cm(3.2).Where: -Spectral scattering index, the amount of white pigments scattering, the unit to be expressed by the reciprocal of film thic

8、kness unit.3.6 Relative scattering power :the ratio of samples scattering index to standard samples scattering index , expressed by percentage.3.7 Reflection factor : means color paste and pigment film in the given solid angle, the ratio of radiative flux in all sides to the radiative flux in the sa

9、me lighting conditions from perfect reflecting diffuser.When the color paste and pigment film reach certain thickness, even if increase the thickness, the ratio will not change.3.8 Reflection coefficient: : the reflection when the color paste or pigment film reach certain thickness, even if increase

10、 the film thickness the reflection will not change.4. Theory:4.1 Colored pigment and black pigmentSame quality of test pitment P1 and standard pigment P2 , scatter separately in the same white color paste, to conduct photometric determination for each dispersions reflectance or reflection coefficien

11、t under condition of mini wavelength of , using value to K/S in the bellow formula and get result of relative tinting strength for the test sample.Where: -K/S value for test pigment or . -K/S value for standard pigment 4.2 White pigments:Same quality of test pigment P3 and standard pigment P4 to con

12、duct photometric determination for each dispersions reflectance factor or reflection coefficient with Y color filter under condition of wavelength 550 nm, using value of K/S in the bellow formula and get result of relative scattering power.Where: -K/S value of for test pigment. -K/S value of for sta

13、ndard sample.5. Material:5.1 Alkyd resin: Mixture based on 60% (m/m) linseed oil and 33%(m/m) phthalic anhydride, should meet requirement bellow:Acid value: not exceed 15mgKOH/g.Viscosity (solvent-free) 710 Pa.sHydroxyl value about 40KOH/g5.2 White pigment pastea. 40 portion, rutile type of TiO2b. 5

14、6 portion, alkyd resin(5.1)c. 4 portion, calcium stearateMix equally the above material with adjusting blade, then put them on triple-roller mill, grinding until the fineness on fineness gage in is less than , store in the sealed vessel, it is better to use soft pipe with svrew cap.5.3 Black pigment

15、 paste Mix up 18.7portion of high carbon black and 81.3 portion alkyd resin with adjusting blade, press for 6 runs on triple-roller mill, get equal fine dispersion. Get the paste 3.25g from 5.3.1 and 91.64 g alkyd resin(5.1) and 5.11g Synthetic silica, mix up them, the mixture through 1 run from tri

16、ple-roller mill, store the black paste in sealed vessel, it is better to use soft pipe with screw cap.6. Instrument6.1 Triple-roller mill6.2 Automatic grinder, the diameter of grind arenaceous glass is 180250mm, add power on grinder about 1 kN, running speed is 70120r/min.6.3 Paste and film vessel,

17、for example, for one appropriate vessel can provide paste film of 250 um thickness.6.4 Photometer, spectrophotometer that can conduct measurement under condition of wavelength between 400nm and 700nm, or D65 light source tristimulus colorimeter.If use tristimulus colorimeter, require that the color

18、filter should be appropriate for the tested pigment, for white pigment, use CIEY color filter.7. Sampling.Select the representative pigment sample according to GB9285.8. Test step Preparation of testing dispersion sampleGet 3 g white paste(5.2) (accurate to 0.01g) and 0.12g test sample (accurate to

19、0.0001g), put white paste in the middle of auto-grinders lower layer. Scattering testing sample on white paste, mix up equally with adjusting balde, close the grinding board and add 1kN power to grind 4 times. Every time should be 25 revolutions, collect the dispersion for use.Note: for the pigment

20、of those difficult to disperse, can increase appropriate grinding revolutions. Preparation of standard dispersion sampleAccording to preparation for test filmMove testing dispersion and standard dispersion separately to paste film vessel, assure that exposed surface is equal and horizontal.8.1. 4Determination of or Measure each films (ie. When max absorption of wavelength