What are the dye index tests?

Dye Appearance Comparison

Reference Standard: GB250-1995 Grey Scale for Assessment of Color Change (eqvIS0105/A02-1993)

Test Method:

1. Dye Particle Size Comparison Method

Place approximately 20g of the test sample and the same weight of the standard sample side by side on a piece of filter paper. Use a glass rod to smooth the surface of the dye. Visually compare the particle sizes of the two.

2. Dye Color Comparison Method

Place approximately 20g of the test sample and the same weight of the standard sample side by side on a piece of filter paper. Use a spatula to smooth the surface of the powder.

Compare the color and brightness differences between the test sample and the standard sample, and evaluate according to the Grey Scale (ISO105/A02-1993).

3. Evaluation Method:

Refer to the Grey Scale for Color Change (eqvIS0105/A02-1993) and classify into five grades.

Solubility

Reference Standard: IS0105-Z09:1995

Equipment and Materials: Balance (accuracy ±0.1g), beaker, glass rod, solubility tester, filter paper, induction cooker

Test Method: 

1. Solubility:

a) Prepare 100ml of water in a 200ml beaker at a specified temperature of 95°C + 2°C. b) Stir 1/10 (±0.01g) of the specified total amount of dye in the beaker at 630 rpm for 30 seconds. After stirring at this temperature for 5 minutes, prepare for filtration.

c) Preheat the Büchner funnel to 95°C and maintain this temperature throughout the filtration process. d) Before filtration, moisten the qualitative filter paper (N0.5A, 15cm) in the Büchner funnel with 95°C water. e) Adjust the vacuum to 3-4 kPa, equivalent to a vacuum of 300-400 mm of water column.

f) Filter the dye solution at 95°C + 2°C, measuring the filtration time with a stopwatch. Then, add 20 ml of water to the beaker, rinse the beaker, and filter again.

9) Allow the filter paper to completely dry at room temperature before evaluation.

h) Determine the degree of dissolution based on the filtration time and the presence of residue on the filter paper. i) Pour the filtrate into a beaker, allow it to cool, and observe the stability of the dye solution at room temperature.

Dye Dust Emission Test

Reference Standards:

GB/T 6693-1997 (eqv IS0 105-Z05:1996)

GB250-1995 Grey Scale for Assessing Color Change (eqv IS0105/A02-1993)

Principle: Dust is generated by passing the dye sample through a dust generator. The dust-laden air is drawn into the beaker using a vacuum and transported to the testing point. The amount of dust generated is quantitatively assessed by visual inspection, gravimetric analysis, or photometry.

Equipment and Materials: Balance (accuracy ±0.1g), dust meter, stopwatch, filter paper, tweezers

Test Method:

a) Secure filter paper (No. 5C) to the filter paper holder, place it on the dust generator, and close the valve to ensure airtightness.

b) Accurately weigh 10g ± 0.1g of dye using a balance and place it in the hopper at the top of the device.

c) Start the timer and quickly open the sliding valve, allowing the dye to fall through the tube to the bottom of the dust chamber.

d) Five seconds after opening the valve, start the vacuum pump. The pumping time is 120 seconds, the flow rate is 5 L/min, and the dye falls to a height of 815 mm ± 5 mm.

e) When the pump stops, turn off the power.

f) Carefully remove the filter paper with dust using tweezers. Visually assess staining using a gray scale.

g) Clean the test apparatus after each test. If washing with damp cloth, be sure to dry completely after washing.