Several Performance Test Methods for Disperse Dyes

Diffusion, dispersion, high temperature dispersion stability, tar content and thermal mobility and other five aspects. The key to these properties is the quality of fillers and lignin mixed into disperse dyes.

Diffusion testing

Accurately weigh 1g dye, add 30mL water 100mL, stir with a glass rod, the suspension of the dye with a straw dripping 4-5 drops on the filter paper, observe its natural osmotic ring, good diffusion is the area Big. Some dye solutions have 1 to 2 layers of bleeder drips. The area is not large. The dye solution is an aqueous solution outside of the circumstance. This kind of dye is best applied with a diffusing agent 20% to 30% of the amount of the diffusing agent MF. Or, add 2g/L disperse dye repair agent to improve the dye diffusivity and improve the dye transferability. Do not apply diffuser N at very warm temperatures because it is not resistant to high temperatures.

Dispersion detection

The remaining dye solution was heated on a constant temperature electric furnace to 70° C. to 72° C., left the heat source, and stirred with a glass rod to observe whether the dye on the beaker wall and the glass rod was sticky. If the fluidity of the dye solution is good, there is almost no stain on the glassware, indicating that the dye has good dispersibility and can be dyed at 100°C or under high temperature and high pressure.

High temperature dispersion stability test

The above dye solution is still poured into a glass stainer cup, placed in a dyeing machine, and treated at 130° C. and 0.18 MPa for 30 minutes. After the removal, it is observed whether the solution is thickened and slowly poured onto the filter paper (filter paper can generally be placed in 50 mL. On beakers), the shorter the filtration time, the better. If a thickened dye solution is observed after heating, a sticky feeling is felt with the finger, indicating that the high temperature dispersion stability of the dye is poor. When the dye is used, measures should be taken to supplement the MF of the diffusing agent in the amount of 20% to 30% of the dye. If the hardness of the water used in production is too high, disperse dyes can cause secondary agglomeration when added to the dye bath. To prevent this, first the pH of the dyeing bath should be stabilized with ammonium sulfate; secondly, the addition of 1 to 2 g/L of dispersed chelating agent can be improved. Must not add sodium hexametaphosphate as a water softener, because sodium hexametaphosphate loses the ability to complex calcium and magnesium ions under high temperature and high pressure conditions, and to a certain extent, it can also increase the pH value of the dye bath and destroy the dye bath. Stability. If there is a slight increase in the color of the surface of the fiber, the color fastness is decreased, and when it is severe, dark color changes occur. In actual production, once the above phenomenon occurs, the clarity of the color can be improved by reduction cleaning, or the addition of a dispersing chelating agent to the reducing bath is more effective.

Tar content detection

Most of the diffusing agents currently produced use crude methyl naphthalene, in which the impurity content is high, not only tar but also other compounds. Generally, after the heated and unheated dye solution is poured on the filter paper, if the filter paper is fine and irregular black spots, it can be regarded as tar and other impurities. If the content of impurities is small, just add some leveling agents with good dispersing emulsifying ability in the prescription, and the problem of moderate or deep coloring is not significant. If there is more tar content, a bright layer of oil-like gold will appear on the surface of the dye solution. 2g/L dispersant WA can be added during dyeing and a small amount of suds suppressor is added before the dye is added. Practice has proved that this "one-off multi-use" identification method is very suitable for printing and dyeing enterprises, and easy to operate.

Thermal mobility detection

After polyester products are dyed with disperse dyes, during the heat treatment such as heat setting and ironing, the dyes inside the fibers migrate out of the fibers and become contaminated with other fibers. It is different from the sublimation fastness, but it can be simulated using sublimation / ironing fastness testing methods. That is, with a piece of dyed polyester, two nylon and vinegar fabrics are attached to both sides, and after hot pressing at 180° C. for 30 seconds, the thermal migration performance is judged on the basis of the color obtained on the attached fabric. Generally, it is better to use a gray card at level 3 or higher, and vice versa. For dyeing products that require high color fastness, dyes with poor thermal migration cannot be used.