The most effective crosslinking reagents for durable press finishing of cellulose fibers are formaldehyde adducts of urea which release formaldehyde during the production and wearing of in such way treated clothes Formaldehyde durable press finishers are applied to the textile substrate mainly in the form of N-methylol and N-alkoxymethyl compounds
Release of formaldehyde from the textile substrate can be measured by:
STANDARD TEST METHODS
Japan Law 112 (EN ISO 14184-1)
The formaldehyde content below 20 mg/kg can not be shown to be caused by the formaldehyde which was released by the crosslinking reagent .
ALTERNATIVE TEST METHODS
edana recommended test method using HPLC
EN ISO 14184-1 standard test method Standard solutions of formaldehyde with concentration levels of 0.3, 0.6, 0.9, 3.0, 6.0, 15.0 and 30.0 mg/L in the 3,5, - diacetyl –1,4-dihydrolutidin forms were prepared. The formaldehyde derivative solution s w ere prepared in water and in matrix (extract from untreated cotton fibers). Six replicates of each concentration level were prepared From the textile substratef ormaldehyde was extracted with water at 40 C , filtered and then converted by using acetyl - acetone reagent to yellow colored compound
V alidation of absorbance measurements on UV/Vis
With Grubbs and Beck statistical test were shown that there were no aberrant values
An F – test was applied to check heteroscedasticity: standard deviation increase with the concentration
Correlation coefficient for standard water and matrix solutions was greater than 0.99
Quality coefficient (QC) was lower than permitted 5%
Anova test shows that the experimental error was smaller than lack of fit (LOF) for the linear calibration curve
Precision of standard water and matrix solutions was better than 10%
The limit of detection (LOD) was 0.628 mg/l
The limit of quantification (LOQ) was 1.197 mg/l
The amount of formaldehyde extracted for each sample can be calculated by:
U ntreated textile material and cross-linking reagent do not contain formaldehyde (7 mg/kg) .
Microcapsule’s wall s contribute to the amount of of the formaldehyde significantly :
The average formaldehyde content for the microencaptulated textile material with empty microcapsules is 715 mg/kg and 766 mg/kg for microencaptulated textile material with microcapsules filled with oils ( both results are obtained by Japan Law method ) .
Results from AATCC test for the same samples are 5.126 mg/kg and 4.174 mg/kg respectively .
indicate that only formaldehyde is released from the textile samples microencaptulated w ith and without essential oil.
Although some amount of formaldehyde is proved in pure essential oil s , amount of essential oil which is applied on textile material with microcapsules (160 g/m 2 ) contribute v e ry little to total amount of formaldehyde. This was proved by the measurements of released formaldehyde after the mechanical damages of microcapsules on the textile substrate
Results given by AATCC test 112-1978 method are expected proportionally higher as results given by EN ISO 14184-1 method.
The a verage results obtained from samles prapered in production line are lower . T hose samples satisfy eco-labeling system’s requirement. T he explanation for this phenomenon is found in different processes of curing and drying.
B y HPLC it was proven that there are no other aldehydes or ketones present on microcapsulated textile materiale
I t was proven that the amount of formaldehyde in essential oils is negligible
M icrocapsule’s wall contributes to the highest degree of the amount of formaldehyde
After washing of textile substrate, the results are considerable lower