GB/T 15344-2020Methods for physical test of talc (English PDF)

3.1 Sampling

3.1.1 The sampling of talc lumps shall be conducted in accordance with GB/T 2010.

3.1.2 The sampling of talc powder shall be conducted in accordance with GB/T 15342.

4.3 Method for pH Value Determination of Water Extract of Talc Powder

4.3.1 Materials and apparatuses The materials and apparatuses required for the pH value determination of water extract of talc powder are as follows:

a) Balance: the division value is not greater than 0.0001 g;

b) Temperature-adjustable electric furnace with asbestos net;

c) Acidity meter: the accuracy is 0.02;

d) Beaker: 250 mL; 100 mL;

e) Measuring cylinder: 100 mL;

g) Filter paper: slow speed;

h) Distilled water: remove carbon dioxide through boiling; cool it down to room temperature; pH value is 6.8 ~ 7.2.

4.3.2 Test procedures

4.3.2.1 Weigh-take about 5 g of sample (accurate to 0.0001 g); place it in a 250 mL beaker.

4.3.2.2 Pour 10 mL of distilled water into the beaker. Use a glass rod to carefully stir it, so as to completely wet the sample. Then, pour in 90 mL of distilled water; mark the height of the liquid level on the outer wall of the beaker.

4.3.2.3 Place the beaker on the electric furnace to boil it, then, adjust the temperature control knob of the electric furnace to below 300 W. Slightly boil it at a low temperature for 5 min (during the process of slight boiling, keep stirring it and supplement the amount of water lost in evaporation); remove it, and cool it down to room temperature. Use a pH meter to determine the pH value of the suspension liquid.

4.3.3 Result expression and tolerances Take the arithmetic mean value of two parallel test results as the report value. In addition, in accordance with GB/T 8170, round it off to two decimal places. If the absolute error of two parallel test results is greater than 0.2, then, the samples shall be re-prepared for the determination.

4.4 Method for Sedimentation Velocity of Talc Powder

4.4.1 Materials and apparatuses addition, in accordance with GB/T 8170, round it off to one decimal place.

4.4.4 Tolerances The absolute error of two parallel test results shall be not greater than 2 mL. Otherwise, the determination shall be re-conducted.

4.5 Method for True Density Determination of Talc Powder

4.5.1 Materials and apparatuses The materials and apparatuses required for the determination of true density of talc powder are as follows:

a) Balance: the division value is not greater than 0.0001 g;

b) Electric-heated thermostatic water bath: the sensitivity is ± 1 °C;

c) Temperature-adjustable electric furnace with asbestos net;

d) Vacuum desiccator with vacuum air pump;

e) Pycnometer: 50 mL;

h) Distilled water.

4.5.2 Test procedures

4.5.2.1 Vacuuming method with pycnometer (Method A) 4.5.2.1.1 Use distilled water to fill a clean and dry pycnometer with an already-known mass (if there are bubbles in the pycnometer, remove them). 4.5.2.1.2 Put on the cap of the pycnometer filled with liquid; place it in a 25 °C ± 1 °C thermostatic water bath for

0.5 h (when the liquid level in the capillary tube of the pycnometer drops, the same liquid shall be added in time to fill it up). Take out the pycnometer; use filter paper to quickly dry the exterior part of the pycnometer. However, DO NOT wipe off water on the capillary end. Weigh it (accurate to 0.0001

g) to obtain m3. 4.5.2.1.3 Pour out the distilled water from the pycnometer, then, dry it again. Fill the pycnometer with kerosene; repeat the steps of 4.5.2.1.2 to obtain m4. 4.5.2.1.4 After washing and drying the pycnometer again, weigh-take about 5 g of the dried sample, put it into the pycnometer. Put on the cap, then, weigh it (accurate to 4.5.2.2.3 Remove the pycnometer; cool it down to room temperature. Then, pour in freshly boiled distilled water that is cooled down to room temperature, so that the water level in the bottle is 2 mm ~ 3 mm below the mouth of the pycnometer. Slowly put on the stopper (at this moment, the capillary shall be filled with water, but there shall be no bubbles); quickly dry the exterior part of the pycnometer. However, DO NOT wipe off water on the capillary end. Weigh it (accurate to 0.0001

g) to obtain m8. 4.5.2.2.4 Pour out the sample and water in the pycnometer. After washing it, pour in freshly boiled distilled water that is cooled down to room temperature, so that the water level in the bottle is 2 mm ~ 3 mm below the mouth of the pycnometer. Use a stopper to plug it; quickly dry the exterior part. DO NOT wipe off water on the capillary end. Weigh it (accurate to 0.0001

g) to obtain m3. Record the temperature of the water at room temperature. 4.5.2.2.5 The density 1 [expressed in (g/cm3)] of the sample shall be calculated in accordance with Formula (5): Where, 2

---water density at t (°C), expressed in (g/cm3), see Appendix A; m8

---the mass of the pycnometer and the distilled water and the sample, expressed in (g).

4.5.3 Results and tolerances Take the arithmetic mean value of two parallel test results as the report value. In addition, in accordance with GB/T 8170, round it off to two decimal places. The absolute error of two parallel test results shall be not greater than

0.1 g/cm3. Otherwise, the determination shall be re-conducted.

4.6 Method for Fineness Determination of Grinded Talc Powder

4.6.1 Materials and apparatuses The materials and apparatuses required for the fineness determination of grinded talc powder are as follows:

a) Test sieve: it shall comply with GB/T 6003.1; the diameter of the sieve frame is 200 mm;

b) Vibrating sieving machine: the number of vibrations is 147 times/min; the radius of gyration is 125 mm; the others shall comply with the stipulations of DZ/T 0118; the end of sieving has been reached. The duration of the rinsing is about 10 min. 4.6.2.1.5 Use distilled water to transfer all the residue on the sieve to a beaker with an already-known mass; place the beaker on the temperature-adjustable electric furnace; conduct low-temperature evaporation, till it reaches dryness. 4.6.2.1.6 Place the beaker in the electrothermal drying oven. At the temperature of 105 °C ~ 110 °C, dry it for

0.5 h ~ 1 h, then, take it out. Place it in a desiccator; cool it down to room temperature, then, weigh it (accurate to 0.0001 g).

4.6.2.2 Vibrating sieving machine method (Method B) 4.6.2.2.1 Weigh-take about 20 g of the dried sample (accurate to

0.01 g); place it into a test sieve with a sieve bottom of a specified pore size. Gently shake it, so as to evenly spread the sample on the sieve. Put on the sieve cover; place it on the vibrating sieving machine frame; properly fix it. 4.6.2.2.2 Turn on the vibrating sieving machine; simultaneously, press the stopwatch for timekeeping. 4.6.2.2.3 After sieving for 5 min, cut off the power supply and stop sieving. NOTE: if manual sieving can reach the same effect, you may also directly sieve by hands without using the vibrating sieving machine. 4.6.2.2.4 Take out the test sieve, together with the sieve cover and the sieve bottom. Use a small brush (without lint) to sweep the talc powder attached to the inner side of the sieve cover and the inner periphery of the sieve frame into the sieve. Conduct manual sieving for 15 s; tap for about 20 times. 4.6.2.2.5 In accordance with 4.6.2.4, check the end point of the sieving. When the ratio of the mass of the sieve residue to the mass of the sample is less than 0.035%, then, it is considered that the end of sieving has been reached. Otherwise, in accordance with the steps of 4.6.2.2.2, continue the sieving for 2 min, then, check the end point of the sieving. Repeat this process, until the end point has been reached. 4.6.2.2.6 After reaching the end of the sieving, transfer all the sieve residue to a watch glass with an already-known mass; weigh it (accurate to 0.0001 g).

4.6.2.3 Airflow sieving method (Method C) 4.6.2.3.1 Weigh-take about 20 g of the dried sample (accurate to

0.01 g); put it into a test sieve with a specified pore size. Gently shake it, so as to evenly spread the sample on the sieve. 4.6.2.3.2 Place the sieve on the sieve base of the rotary airflow screen; put on the sieve cover. 4.6.2.3.3 Turn on the airflow screen; simultaneously, press the stopwatch for timekeeping. During sieving, control the negative work pressure to 3 103 Pa; use a small wooden hammer to gently tap the screen cover or the screen frame, so that the talc powder attached to the screen cover or the screen frame may fall into the sieve. 4.6.2.3.4 After sieving for 30 s, cut off the power supply and stop sieving. 4.6.2.3.5 Take out the test sieve, together with the sieve cover. Use a small brush (without lint) to sweep the talc powder attached to the inner side of the sieve cover and the inner periphery of the sieve frame into the test sieve. Conduct manual sieving for 15 s; tap for about 20 times. 4.6.2.3.6 In accordance with 4.6.2.4, check the end point of the sieving. When the ratio of the mass of the sieve residue to the mass of the sample is less than 0.035%, then, it is considered that the end of sieving has been reached. Otherwise, in accordance with the steps of 4.6.2.3.2 ~ 4.6.2.3.4, continue the sieving for 15 s, then, check the end point of the sieving. Repeat this process, until the end point has been reached. 4.6.2.3.7 After reaching the end of the sieving, transfer all the sieve residue to a watch glass with an already-known mass; weigh it (accurate to 0.0001 g).

4.6.2.4 Sieving endpoint check 4.6.2.4.1 Put the test sieve with sieve residue on the clean bottom of the sieve. Lift the sieve; lightly tap the sieve frame; tap for about 80 times per minute. After sieving for 1 min, stop the sieving. 4.6.2.4.2 Remove the bottom of the sieve; use a small wool sieve to transfer the sieve residue on the bottom of the sieve into a watch glass with an already-known mass; weigh it (accurate to 0.0001 g). 4.6.2.4.3 When the ratio of the mass of the sieve residue to the mass of the sample is less than 0.035%, then, it is considered that the end of sieving has been reached.

4.6.3 Result calculation The passing rate X2 [expressed in (%)] shall be calculated in accordance with Formula (6): Where, m9

---the mass of the beaker (or the watch glass) and the sieve residue, expressed in (g); m10

---the mass of the beaker (or the watch glass), expressed in (g);

4.9 Method for Fineness Determination of Fine and Ultrafine Talc Powder

4.9.1 Materials and apparatuses The materials and apparatuses required for the fineness determination of fine and ultrafine talc powder are as follows:

a) Ultrasonic disperser;

b) Beaker: 200 mL;

c) Laser particle size analyzer: 0.1 µm ~ 1,000 µm;

d) Dispersion medium: sodium hexametaphosphate solution (2 g/L) or other appropriate dispersing agents.

4.9.2 Test procedures In accordance with GB/T 19077, conduct the test.

4.10 Method for Magnet Extract Determination of Talc Powder

4.10.1 Materials and apparatuses The materials and apparatuses required for the determination of magnet extract in talc powder are as follows:

a) Balance: the division value is not greater than 0.0001 g;

b) Balance: the division value is not greater than

0.1 g;

c) U-shaped permanent magnet: the magnetic flux is not less than 0.9 10-

4.10.2.1 Weigh-take about 200 g of the sample (accurate to

0.1 g); place it on a clean paper. Spread it into a thin layer with a thickness of not more than 2 mm.

4.10.2.2 Use a clean, thin paper to wrap the magnet; move the magnet back and forth for several times at a distance of 5 mm ~ 10 mm from the surface of the sample.

4.10.2.3 Place the magnet on another piece of clean paper; open the paper wrapping the magnet, so that the magnetic particles fall on the paper.

b) Scraper fineness meter;

c) Mixer: the rotating speed is 1,000 r/min ~ 2,000 r/min;

e) Butyl acetate;

f) Plastic beaker: 500 mL;

g) Scraper: made of steel.

4.12 Method for Scraper Fineness Determination of Talc Powder...

4.12.2.1 Accurately weigh-take

55.0 g of alkyd resin; place it in a plastic beaker.

4.12.2.2 Accurately weigh-take

25.0 g of the sample, and also put it into the plastic beaker. Then, add 5 mL of butyl acetate.

4.12.2.3 Place the beaker on the mixer; stir it for 5 min, so as to thoroughly mix the sample with the resin. Then, let the beaker stand for 10 min.

4.12.2.4 Use a clean knife to take an appropriate amount of the well-mixed test liquid; place it in the deepest part of the chute of the scrapper fineness meter.

4.12.2.5 Use the thumb, the index finger and the middle finger of both hands to firmly grasp the scraper. Horizontally place it on the upper end of the scraper fineness meter; make the edge of the scrapper vertically touch the surface of the scraper fineness meter and completely coincide with it. Then, quickly pull from the deep part to the shallow part of the chute; immediately (within 5

s) observe and record the maximum scale (accurate to 1 µm) where the particles are uniformly exposed in the chute. This numerical value is the scraper fineness of the sample.

4.12.3 Result expression and tolerances Continuously perform the steps of 4.12.2.4 ~

4.12.2.5 for 5 times. The result shall be subject to the 2nd big data among the 5 data. Take the arithmetic mean value of two parallel test results as the report value. In addition, in accordance with GB/T 8170, round it off to an integer. The absolute error of two parallel test results shall be not greater than 10 µm. Otherwise, the determination shall be re-conducted.

4.13 Method for Oil Absorption Determination of Talc Powder

4.13.1 Materials and apparatuses The materials and apparatuses required for the determination of oil absorption of talc m18

---after oil-dripping, the mass of the dropping bottle and the refined linseed oil, expressed in (g); m

---the mass of the sample, expressed in (g). Take the arithmetic mean value of two parallel test results as the report value. In addition, in accordance with GB/T 8170, round it off to two decimal places.

4.13.4 Tolerances The absolute error of two parallel test results shall be not greater than

2.0 g/100 g. Otherwise, the determination shall be re-conducted.

4.14 Method for Burnt Whiteness Determination of Talc Powder

4.14.1 Materials and apparatuses The materials and apparatuses required for the determination of burnt whiteness of talc powder are as follows:

a) Whiteness meter: it shall comply with the stipulations of GB/T 5950;

b) Balance: the division value is not greater than 1 g;

c) Box-type high-temperature furnace: the highest temperature is not lower than 1,400 °C; the temperature control accuracy is ± 10 °C.

4.14.2 Sample processing

4.14.2.1 Weigh-take about 100 g of talc powder sample; place it into a crucible.

4.14.2.2 Place the crucible containing the sample in a high-temperature furnace. Slowly raise the temperature from a low temperature to 1,280 °C. At this temperature, maintain it for 60 min.

4.14.2.3 Then, take out the crucible containing the sample; put it in a desiccator to cool it down to room temperature.

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