Study the Yellowing Factors of Pre-cat Etherified DMDHEU Resin
|Keywords||Precatalyzed 2D resin Anti-crease After baking Clothing Yellowing|
Dimethylol dihydroxy ethylene urea resin (ie DMDHEU referred 2D resin) is currently the most widely used anti-crease finishing agent. 2D resin has four hydroxyl groups can be reacted with the cellulose fibers crosslinked network, so its cotton, viscose and blended fabric with good durable press finishing effect. However, 2D and formaldehyde emission resin-yellowing big disadvantage. Reduce N-methylol amide resin formaldehyde release an effective way the resin hydroxyl molecules etherification, a common methylated, ethereal, ethylene glycol and polyethylene glycol ethers and so on. The modified resin in general use, general finishing process conditions, whiteness, formaldehyde content can be reduced to a satisfactory level. This two-step synthesis from 2D resin finishing process conditions and process conditions to explore the impact of 2D resin yellowing various factors. In the synthesis stages: discovery of residual glyoxal resin inside its derivatives can cause yellowing, this problem has been confirmed by experiments; different manufacturers glyoxal, glyoxal and its derivatives are not the same content, degree of yellowing of synthetic resin are different, It was found, BASF produced minimal yellowing glyoxal; 2D Resin different synthesis conditions, glyoxal and the reaction conversion rate byproducts rate is not the same, B dialdehyde conversion and the reaction byproducts caused by resin yellowing rate is one of main factors. When synthesis conditions: the reaction pH = 4, the reaction time was 2h, the reaction temperature is 50 ~ 55 ℃, the reaction byproducts in the lowest, then the resulting resin yellowing min. Aspect ratio of the raw material, glyoxal, urea, formaldehyde molar ratio of 0.99 ︰ 1 ︰ 1.8, the resultant resin is preferably whiteness; the etherification stage, 2D resin etherified hydroxyl group in position 4 and 5 can cause yellowing of the resin, etherification optimum conditions: the reaction temperature is 50 ~ 55 ℃, the reaction time was 30min, the reaction pH of 3-4. Finishing process conditions: magnesium chloride hexahydrate as catalyst with the best whiteness, and the amount of 5% to 6%; finishing working solution pH is not less than 5; small Ca 2 sup>, Fe 2 sup>, Cu 2 sup>, Al 3 sup> metal ions does not affect the finishing fabric whiteness; finishing work was added in urea formaldehyde capture diethylene glycol, etc. agents will reduce the finishing fabric whiteness; With the increase of the amount of resin, curing time, finishing fabric whiteness gradually decreased.