https://doi.org/10.15255/KUI.2002.034
Published: Kem. Ind. 52 (7-8) (2003) 327–333
Paper reference number: KUI-34/2002
Paper type: Original scientific paper
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A Comparison of Conventional and New Ecologically Acceptable Durable Pres Finishing Agents

S. Bischof Vukušić, D. Katović and I. Soljačić

Abstract

Alternative chemical methods have been explored to provide the same croslinking performance using formaldehyde-free chemicals. The most recently introduced approach, that requires more aggresive cure temperatures and a phosphorous containing catalyst, is PCA croslinking. These reactants form an anhydride between adjacent carboxyls, anhydride then reacts with the hydroxyl group of the cellulose, producing an ester group croslink that has a high stability and durability. Posibility of application DP finishing products with low formaldehyde content (modified DMDHEU) and formaldehyde free (FF) products (modified dimethyl glyoxalurea), has been investigated in this paper. Application of mixture of these products has lowered the content of free formaldehyde from č1200 ppm, resulting from application of modified DMDHEU, to č600 ppm (showed at fig. 2). Washing proces after the treatment has lowered further the content of free formaldehyde to les than 20 ppm, which fulfils even the most rigid regulations on the allowed content of free formaldehyde on textile materials. The best results of WI have been obtained with N-methyl products and lower results with applied PCA. Citric acid has shown the lowest results of WI, because of its greatest sensitivity to high cure temperatures. Under these temperatures it decomposes to unsaturated acids (aconite, itaconic and citraconic) whose double bonds are the main cause of the yellownes. Some of the PCA have shown equaly good, or even better, resilience effects compared to the conventional N-methylol agents. The greatest disadvantage of N-metylol products is tensile strength decrease, which have been partialy improved by application of etherified DMDHEU and significantly improved with the aplication of PCA. According to our investigations application of PCA has caused lowest shade changes after the DP treatment of dyed cellulose material. Greatest shade changes have been caused with the usage of Zn-nitrate catalyst (fig. 3- baths 4 and 6). Commercially, the modified DMDHEU (glicolated or methylated) is the one that is still most used today. With these products the most popular catalysts are magnesium based ones. The negative aspect of the catalysts is that they induce degradation of the cellulose as indicated by the decrease of the tensile strength of cotton fabric. Conventional DP finishing agents which are still mostly applied products, are tried to be maximally improved from the ecological point of view, since they are still in the usage, primarily, because of the economical reasons. Main alternatives to conventional N-methylated products are PCA, which are offering fulfilment of, both, ecological and economical requirements. Some of these products have already been commercialised and represent the most recent technology to challenge the existing line of formaldehyde-based products.

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Keywords

durable pres finishing, formaldehyde free, DMDHEU, DMGU, PCA