The experiment of dyeing temperature and dyeing bath ratio of CD cationic pigment paste

The experimental purpose: CD series textile cationic dyeing water based pigment paste developed by ourselves can directly combine with fabric cellulose matrix. The particle size of pigment dispersed in pigment paste is about 2 microns, color is depth and vividness, so can be made "one-step dyeing" with it. This dyeing process is simple, can save energy and labor, reducing colored waste water discharge. And this experiment purpose is finding out the suitable bath ratio of CD water based pigment paste, in order to make the data preparation for users.

The experimenters: CD product project team members of Shanghai Caison R&D Dept.

The experimental material: CD series textile cationic dyeing pigment paste, matched CAISON CDB-1 cationic binder, cotton knitted fabric 105g/m2.

The experimental equipment: commonly small equipment in lab;

The testing method: dip dyeing way, preparing different ratios of CD cationic pigment paste liquid, then make dyeing rate calculation after dyeing finished when using different dyeing temperstures， and record the data.

The standard dyeing liquid ratio: separately formulate 1mg/L, 2.5mg/L, 5mg/L, 7.5mg/L, 10mg/L, 15mg/L, 20mg/L.

Testing a certain concentration of dip dyeing, then take out some residue dyeing liquid and dilute to a lower concentration according to certain proportion,  making the comparison with standard concentration of dyeing liquid and determine the concentration diluted. At last, calculating the residual liquid concentration Ci before dilution. The dyeing uptake is calculated as follows:

The dyeing uptake = (1 - Ci / Co) × 100%

 Co---- dyeing liquid concentration before dyeing;

 Ci---- dyeing liquid concentration after dyeing;

Experimental results

1. Temperature factor：

The dye uptake of dip dyeing with CD series pigment paste is higher than normal pigment paste, 6-8% dyeing concentration is almost dyed fully. So we just to choose the lower concentration which also can reach the same dyeing uptake to check the connection of completion time and tempreature.

According to this experimental result, CD series pigment paste dyeing in higher temperature is better for reducing of residue concentration after high concentration dyeing. But we can find that over high dyeing liquid temperature will cause color creases on dyed fabric. So the low temperature is needed at the beginning of dyeing process, to avoid bigger dyeing uptake and unevenly dyeing. Now we can know that CD series cationic pigment paste dip dyeing would make uniform heating way of first low and ther high, and heating temperature should not be too high. The dyeing process is just uniform heating and then heat preservation.

Dyeing principle of CAISON CD series cationic water based pigment paste, is the pigment fine particles are being on competitive situation of textile fibers electrostatic interaction and water surface tension during the textile dyeing process. When the electrostatic force is greater than the surface tension, the pigment fine particles will be adsorbed on the textile fibers. When textile fiber is fully absorbed by pigment particles, the diffusion movement of pigment particle is more intense, pigment particle is easily released from the fabric. If higher temperature, this phenomenon is more obviously. So the temperature holding time of the dip dyeing should not be too long.

2. Dyeing bath ratio confirmation.

The dyeing bath ratio is the key point that pigment dyeing paste and textile fiber can reach the equilibrium concentration. Controlling the dyeing bath ratio is very important for textile dyeing effect. This experiment is to test the ratio and each amount of CD cationic pigment paste, water and textile fabric in the dyeing process.

CD series cationic pigment paste is the same as reactive dyes, dyeing ratio has a certain influence on the dyeing depth of textile fabrics.

When the pigment paste amount is a certain, the dyeing uptake will decrease along with the bath ratio is increasing, and the residual pigment paste amount will increase based on it. For the dyeing levelness, when bath ratio is lower, dyeing is unevenly. And the bath ratio reaches 1:30, the dyeing liquid is almost colorless when dyeing is finished. 

So the conclusion of this testing is that the reasonable dyeing bath ratio is 1:30 for CD series cationic water based pigment paste.