What is Dacron?
The basic component of Dacron is polyethylene glycol terephthalate, and its molecular formula is [-OC-Ph-COOCH2CH2O-]n; it is also called polyester fiber (PET).
The production and properties of Dacron oligomers:
Start with the polymerization principle of Dacron, here are three stages of Dacron synthesis:1. start stage: monomers turn to oligomers ;
2. middle stage: oligomers are converted into polymers;
3. later stage: the molecular weight of the product increases, the viscosity increases, and the reaction stops.
The main component of Dacron oligomer is cyclic trimer, and its structure is the same as below:
The cyclic trimer has a highly symmetrical structure and is easy to accumulatively crystallize. The melting point of the cyclic trimer is 310 degrees centigrade, and its thermal stability and chemical stability are relatively higher. The cyclic trimer accounts for more than 70% of the Dacron oligomers. When the disperse dyes are dyed at 130-135 DEG C, the solubility is less than 2mg/L. Therefore, it is difficult to remove in the dyeing process of Dacron.
Another structure of Dacron oligomer is linear oligomer. Linear oligomer accounted for about 25% of Dacron oligomer, and there are polar groups in its molecular structure. It has some kind of solubility in water and has little effect on the dyeing of Dacron.
To sum up, the main influencing element of the dyeing of Dacron oligomer is cyclic trimer.
Effects of Dacron oligomer on dyeing:
1. Oligomers deposit in the dyeing equipment , effecting the circulation and heat transfer of dye liquor;
2. Oligomers are deposited on the fabric and it causes color differences and stains;
3. Oligomers migrate from the inner of fiber to the surface, affecting the feel and appearance;
4. Oligomers cause the friction of yarn increases, causing the decline of yarn quality.
5. Oligomers coalesce with disperse dyes to form stains that are difficult to remove.
1. Dyeing under alkaline conditions, the ester groups of oligomers are easy to hydrolyze and produce water-soluble carboxylic acid sodium groups, which can reduce the concentration of oligomers in solution and inhibit the precipitation of crystals. Alkali resistant disperse dyes are already used in some varieties.
2. Oligomer inhibitor, a high temperature-resistant oligomer inhibitor allows oligomers to disperse at high temperatures and reduces crystal precipitation. Oligomer inhibitor is generally anionic, nonionic, surface active compounds, to know more about it, you can go and check the model of Oligomer Inhibitor DF-30.
3. High temperature drainage, this method can reduce the attachment of oligomer.
4. Biological enzyme treatment, the relative data shows that the enzyme can effectively break the cyclic trimer, and with good dispersion of surfactant, it can remove oligomer.