GB/T 5211.12-1986 Determination of resistivity of aqueous extracts of pigments GB/T5211.12-1986 Standard download decompression password: www.bzxz.net

National Standard of the People's Republic of China
Determination of resistivity of the aqueous extract of pigments
Determination of resistivity of the aqueous extract of pigments
This standard specifies the general test method for determining the resistivity of the aqueous extract of pigments1) (specific resistivity). This method is applicable to all pigments (except those that are obviously soluble in water). UDC 667.622
GB 5211.12-86
This standard is equivalent to the international standard ISO787/141973 "General test methods for pigments and extenders - Part 14: Determination of resistivity of aqueous extracts". bZxz.net
Note: ① The resistivity of the aqueous extract of pigments is only a property of the pigment and has nothing to do with the amount of water-soluble substances. ② The standard temperature for determination is 23℃. However, different temperatures may be used after consultation between the relevant parties, as long as necessary corrections are made to take into account the temperature difference. ③When this general method is applicable to a specific pigment or extender, it is sufficient to refer to the terms of this method in the product standard of the pigment or extender and indicate the changes required due to the characteristics of the product. Only when this general method is not applicable to a specific product should a special method be specified to determine the resistivity of the water extract.
1 Reagents
All reagents used are analytically pure.
1.1 Pure water, resistivity not less than 25002·m (conductivity not higher than 0.4×10μS/cm). 1.2 Alcohol, resistivity not less than 25002·m (conductivity not higher than 0.4×10μS/cm). 1.3 Potassium chloride solution, 0.02mol/L
2 Apparatus
2.1 Centrifuge or high-speed centrifuge (use when necessary). 2.2 Filter paper, slow quantitative filter paper, diameter 12.5~18cm. Wash with pure water until the resistivity of the filtrate is greater than 20002·m (conductivity is not higher than 10.5×10μS/cm).
2.3 Beaker, 100ml, or other container suitable for matching with conductivity electrode. 2.4 Thermometer, minimum graduation is 0.2℃. 2.5 Bridge or conductivity meter 2)
2.6 Conductivity electrode, conductivity cell constant K is about 1.3 Determination of conductivity cell constant\)
3.1 The method for preparing potassium fluoride standard 1 solution is to dilute potassium chloride solution (1.3) with pure water (1.1) to a known concentration (see Notes ① and ②), and use conductivity electrode (2.6) to measure the resistance R or conductivity C of the solution at 23℃. Instructions for use:
1) ISO787/14 stipulates the determination of resistivity, while this standard also determines conductivity. The relationship between resistivity (p,) expressed in Q,m and minimum conductivity (1,) expressed in μS/cm is 10-10 × 10'.
2) ISO787:14 uses a bridge to measure resistivity, while this standard also uses a conductivity meter. Applicable conductivity meters include DDS-11A. 3) 1SO787/14 measures the liquid resistance when measuring the conductivity cell constant and obtains K using formula (1). This standard lists the solution conductivity formula (2) for obtaining K.
Published by the National Bureau of Standards on August 26, 1986
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Implementation on August 1, 1987
GB 5211.12—86
3.2 Calculate the conductivity cell constant K according to formula (1) or (2). KR
武：R -—
-Measured resistance, 2;
p-—-Resistivity of potassium chloride solution at the concentration used at 23℃, 2·m (0.002mol/L solution is 34.4Q·m see Figure '
Conductivity of potassium chloride solution at the concentration used at 23℃, μS/cm; Conductivity measured by conductivity electrode, μS.
Note: (! If potassium chloride solutions of different concentrations are used, the corresponding 0 is obtained from the figure.②·Generally speaking, changing the concentration of potassium chloride solution has little effect on the conductivity cell constant, but for high accuracy, a potassium chloride solution of a fixed concentration must be used, whose resistivity is similar to that of the solution to be measured. When using a bridge for measurement, the measured value should be located at the middle 1/3 of the dial.00 .
·8 Li Shen
4 Test steps
Carry out parallel determination of two samples.
4.1 Water wettability test of pigment
Resistivity of potassium chloride at 23℃
Concentration mol/L
Take a small amount of pigment, add boiling distilled water, and observe the water wetting. If the sample is easily wetted by water, follow the operation method in 4.2. If the sample is not easily wetted by water, it indicates that it is hydrophobic, and follow the operation method in 4.3. 1204
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GB 5211.12-86
4.2 Hydrophilic pigments
4.2.1 Weigh 20±0.01g of the pigment sample and transfer it to a weighed beaker of appropriate volume 41. Note: * Generally speaking, a 250ml beaker is suitable, and a 400ml beaker is best for some pigments that are prone to foaming. To prevent foam overflow when boiling, organic pigments usually use a 600ml beaker.
Add 180g of boiling hot pure water (1.1), slowly boil for 5 minutes under constant stirring, cool to about 60℃, add water to a net weight of 200g, stir well, filter directly with filter paper (2.2), discard the first 10ml of filtrate, and filter the filtrate into a clean and dry beaker (2.3) 41. When using a centrifuge or high-speed centrifuge to separate pigments, wash the test tube, or rinse the test tube with a small amount of slurry, and pass the separated upper clear liquid through the filter paper. , discard the first 10ml of filtrate. 4.2.2 Rinse the conductivity electrode (2.2) with pure water (1.1) and then with the filtrate, place it in the filtrate 4, move the conductivity electrode up and down to remove air bubbles, adjust the filtrate temperature to 23±0.5℃, immerse the conductivity electrode about 10mm below the liquid surface, and position it upright in the middle of the beaker, and read the resistance or conductivity value with a bridge or conductivity meter (2.5). At 23±0.5℃ At least 5 measurements should be made. When using a bridge, the reading should be as close to the middle of the scale as possible. 4.3 Hydrophobic pigments
Weigh 20±0.01g of the pigment sample, transfer it to a weighed beaker of suitable volume, moisten it with 4-16g of methanol (1.2), and stir well. While stirring, slowly add boiling pure water (1.1) to obtain a uniform slurry, then dilute it with boiling pure water to a total of 200g and stir well. Cool to about 60℃ and filter directly with filter paper (2.2), discard the first 10ml of filtrate, filter the filtrate into a clean and dry beaker (2.3), and measure according to 4.2.2.
Representation of results
Calculate the resistivity p, (2·m) of the pigment water extract at a specified temperature t℃ according to formula (3). pr
The average value of the measured resistance, 2,
Formula i: R,-
Conductivity cell constant.
Calculate the conductivity Lt (μS/cm) of the pigment water extract at the specified temperature t℃ according to formula (4). Lt
Where: C,————the half mean of the measured conductivity value, μS. Note: When using a conductivity meter for measurement, the instrument has a conductivity cell constant adjustment device, which can directly read L. Take the average value of two measurements and express the result accurate to 1%. Test report
The test report shall at least include the following:
Type and name of the test pigment
Amount of methanol (for hydrophobic pigments)
Differences from the operation specified in this test, especially temperature; whether the test pigment is hydrophilic or hydrophobic,
Test results as described in Chapter 5,
Test date.
（3）
（4）
Additional Notes:
GB 5211.12-86
This standard was proposed by the Ministry of Chemical Industry of the People's Republic of China and is under the jurisdiction of the National Technical Committee for Standardization of Paints and Pigments. This standard was drafted by the 13th Working Group of the Technical Committee for Standardization of Pigments Testing Methods. The main drafter of this standard is Zhang Xiuyun.
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