GB/T 7048-2012Colour carbon black -- Determination of blackness (English PDF)

5.4 of this Edition);

- Deleted the provision on syringe volume, and only its accuracy was specified (5.5

of GB/T 7048-2003; 5.5 of this Edition);

- Added "dryer" (5.6 of this Edition);

- Added "tough, conical" to "ink knife" (5.6 of GB/T 7048-2003; 5.7 of this Edition);

- Deleted "Figure 1" of GB/T 7048-2003, and added Figure 1 of this Edition;

- Deleted the provisions on the size of glass plates (5.7 of GB/T 7048-2003; 5.9 of

this Edition);

- Changed "ink film-making device" to "ink film-making device, groove depth (0.07

~0.10) mm, capable of preparing a film with uniform thickness (see Figure 1)"

(5.9.2.1 of GB/T 7048-2003; 5.8 of this Edition) ;

- Deleted the "glass slide film preparation method" and related instruments and

analysis steps h. At the same time, changed the numbering and content of the

analysis steps accordingly (5.9, 8.8, 8.8.2, 8.9.2 of GB/T 7048-2003; Chapter 8

of this Edition);

- Edited the provisions on drying of the sample in "Sampling" of the previous edition

into the steps of this Edition, and made appropriate modifications. At the same

time, added notes (6.2 of GB/T 7048-2003; 8.1.1 of this Edition);

- Added "Place the ink slurry on one end of a smooth and clean glass plate (5.9) for

Colour carbon black - Determination of blackness

WARNING -- Personnel using this standard shall have practical experience in

regular laboratory work. This standard does not point out all possible safety issues.

Users are responsible for taking appropriate safety and health measures and

ensuring that the conditions specified in relevant national laws and regulations are

met.

8.1 Preparation of ink slurry (prepare double ink slurry)

8.1.1 Dry an appropriate amount of carbon black specimen and standard specimen (4.3)

according to the provisions of GB/T 3780.8. Place them in a desiccator (5.6) to cool to

room temperature.

NOTE: Carbon black shall not be re-dried.

8.1.2 Weigh (0.4±0.000 1) g of the dried test specimen and standard specimen (8.1.1)

respectively.

8.1.3 Place a weighed portion of carbon black in the center of the lower plate of the mill

(5.2).

8.1.4 Use a syringe (5.5) to draw 2.0 mL of refined linseed oil 4# (4.2). Add it to the

carbon black on the lower plate. Use an ink knife to mix the carbon black and refined

linseed oil 4# thoroughly. Apply a round cake in the center. Clean the ink sticking to

the ink knife as much as possible onto the plate of the grinder. Minimize the loss of ink.

8.1.5 Close the upper plate of the grinder and start grinding at a pressure of 0.017 MPa

for 50 r.

8.1.6 Open the upper plate. Use the ink knife to transfer the ink slurry adhering to the

upper plate to the lower plate as much as possible. Then, as the lower plate rotates, use

the ink knife to collect all the ink slurry at the center of the lower plate. Clean the ink

slurry adhering to the ink knife as much as possible onto the plate of the grinder. Close

the upper plate. Continue grinding for 50 r. Repeat this operation 3 times. Grind the ink

slurry for a total of 200 r.

8.1.7 Collect the ink on sulphuric acid paper or glass paper (4.5) or place it on one end

of a smooth and clean glass plate (5.9) for later use.

8.1.8 Clean the grinding machine plate with a solvent (e.g., ethanol) (4.1) and cotton

wool or soft tissue paper (4.4).

8.2 Preparation of ink film

8.2.1 Use the ink applicator (5.8) to scrape the ink from one end of the glass plate to the

other end within 2 s~3 s with appropriate and stable pressure to form an ink film.

8.2.2 The width of the ink film is about 50 mm. The surface shall be uniform, flat and

opaque. Otherwise, collect the ink with an ink knife and repeat the steps in 8.2.1 until

a satisfactory ink film is obtained.

8.3 Determination of ink reflectivity

8.3.1 Adjust the reflectometer to "0" according to the instrument manual.

8.3.2 Place the standard ink film carrier under the reflectance head. Align the light hole

of the reflectometer with the surface of the ink film (the part 20 mm away from the two

ends of the ink film is not considered). Turn the instrument calibration knob. Set the

reflectivity to 50 (scale). Measure the reflectivity of four different parts. Read the

readings after the instrument stabilizes (15~20) s. If the four readings are all between

49.5~50.5, it is considered to meet the requirements, otherwise prepare a new standard

ink film. At the same time, measure the reflectivity of another standard ink film.

8.3.3 Place the sample ink film carrier under the reflectivity head. Align the light hole

of the reflectometer with the surface of the ink film (the area 20 mm away from both

ends of the ink film is not considered). Measure the reflectivity of the ink at 4 different

locations. After the instrument stabilizes (15~20) s, record each reading and take the

average value.