With the continuous improvement of baby nappy technology, more and more people pay for it. At present, the basic performance technology of my country's baby nappy industry has tended to be perfected and gradually extended to wearing comfort. Therefore, the situation of each user is different, and the design of the product should also tend to be flexible. To this end, after understanding the characteristics of spandex, we now need to test whether it can really be used in product manufacturing?
Spandex is mainly dry-spun, generally using dimethylformamide (DMF) or dimethylacetamide (DMAC) as a solvent. During the curing process, the diffusion of the solvent inside the fiber to the surface is hindered, so that the harmful solvent cannot be completely volatilized, and eventually the solvent remains. At present, some developed countries have begun to explicitly prohibit the use of dry-spun spandex yarns with excessive DMF solvent residues. As the raw material of the sanitary product baby nappy, it should meet the requirements of low solvent residual rate, environmental protection, non-toxicity, and hygiene.
Many data report quantitative measurement methods of DMAC or DMF, such as washing-drying method, gas chromatography, etc., but these methods have strict requirements on operation or instruments, either low efficiency or poor reproducibility, and have certain limitations in practical analytical work . Qualitative and quantitative analysis are based on the wide application of infrared spectrometers, which are simple, intuitive and fast. On the basis of previous experiments, Sun Zhenbo established a rapid qualitative and quantitative analysis method for the residual rate of solvent (DMF or DMAC) in spandex. Select 1690cm-1 or 1665cm-1 as the analysis object, and perform quantitative analysis using the relative peak value of absorbance.
Spandex used in textile belts is usually added with silicone oil to promote high-speed production of belt looms, which is beneficial to reduce the adhesion and friction factor of the material and improve the anti-static performance. Taking into account the requirements of hot melt adhesive bonding performance, the spandex used in the baby nappy field must strictly control the oil content. In the "Chemical Fiber Oil Content Test Method" standard, the reference for the detection of oil content is pointed out.
Put the fiber into boiling water and boil, and get the ratio of the fiber shrinkage length to the original length, this data is the boiling water shrinkage rate. It is an indicator of fiber stability, expressed as a percentage, with different central values depending on the variety of fibers. The boiling water shrinkage rate of the fiber is closely related to the inside of the fiber, which reflects the residual internal stress in the fiber. The boiling water shrinkage rate increases with the increase of the internal stress. The data results of the boiling water shrinkage rate not only affect the formulation of the processing technology, but also the quality of the processed products. The spandex with high boiling water shrinkage rate is more tough and not easy to break.
There are other test indicators, but through a series of test results, it is not difficult to find that spandex as its manufacturing material is feasible under the premise of meeting the performance of baby nappy.