Chemistry of easy-care and durable press finishes

4 Chemistry of easy-care and durable press finishes  

Urea-formaldehyde (U/F) products are readily synthesised from water solutions of urea and formaldehyde at pH 7.5-9. The resulting iV,iV-dimethylol urea (DMU) is often modified by further reaction at pH 8-9 with methanol to the more stable and liquid dimethylether of DMU (dimethoxymethyl urea) as shown in Fig. 5.1. These reactions are equilibrium reactions with significant concentrations of the starting compounds. These equilibria are the reasons for the high content of free and easily released formaldehyde found with U/F products. Because of their high reactivity, unmodified U/F finish baths must be used within a few hours. The high stiffness and firmness of the U/F finish can be important for rayon fabrics which often are considered too limp when compared with cotton. The U/F finish gives the best elastic resilience.  

DMU is highly reactive finish baths have to be used in a few hours Low stability to hydrolysis, low durability to laundering High chlorine retention 

High content and release of formaldehyde Very high elastic resilience. 

A typical DMDHEU commercial product is made from about 45 % DMDHEU, 9 % diethylene glycol and 2 % methanol. This product could contain less than 

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