| Pigment printing is one of the most important printing techniques in the world. Unlike other printing techniques, pigment printing is able to cover the whole spectrum of prints on almost all substrates practically. Essential reasons for the success of pigment printing include the simplicity of the process, the fact that no cost-intensive afterwash is necessary, and the fact that it is one of the techniques of least pollution ecologically.Pigments have no natural affinity to fibers and they must be bonded to fibers by a high molecular weight film-forming polymer, namely binder. Binder plays a paramount role in pigment printing because it is responsible for the holding of the non-substrate pigments onto the fabrics and it has great influences on the performance of the printed fabrics, especially on the handle and color fastness. In order to increase the abrasion-resistance of the print on the fabric to washing or rubbing, monomers containing multi-functional groups (mainly N-hydroxymethyl acrylamide in China) are usually adopted to produce cross-links within binders and between binders and cellulose. But this results in a big problem: the content of free and released formaldehyde on the finished pigment printed textiles is as high as 5OOppm, much higher than the eco-standards of 300ppm for outer garments and 20ppm for baby wear, which are the standards laid down by Europe. It is known that formaldehyde is a skin irritant, and it will give rise to potential problems of dermatitis if such textiles are worn next to the skin. Therefore, great concerns have been focused on the reduction or eliminationof released formaldehyde on pigment prints.An alternative approach is to develop a novel cross-linking system, which does not release free formaldehyde after printing. It is with this idea that we set the major task to synthesize a new kind of eco-friendly and self-crosslinkable binder to replace melamine formaldehyde based binders.The main task and conclusions are shown as below:1 In order to find a new kind of self-crosslinkable monomer, which could replace the traditional cross-linking monomer N-hydroxymethyl acrylamide but not affect the final properties of the binder, several multifunctional reactive monomers were selected and used in the binder. A new kind of self-crosslinking system composed of soft monomer BA, hard monomer St, and self-crosslinking monomer GA, multifunctional reactive monomer M and hydrophilic monomer AA was designed. The results show that there are some mutual influences between reactive monomer M, glycidyl acrylate and acrylic acid. The properties of the binder are the best when the ratio among them is the same. The new binder does not release free formaldehyde and the handle and color fastnesses of the printed fabric surpass those of fabrics treated by the traditional binders, which use N-hydroxymethyl acrylamide as the self-crosslinking monomer.2 Synthesizing parameters of glycidyl acrylate were studied. Glycidyl acrylate is a multi-functional monomer, which has high reactivity but is usually difficult to be synthesized and separated. Based on the fact that using sodium acrylate instead of acrylic acid to react with glycidyl chloride could improve the yield of GA, and the fact that glycidyl chloride could solve the mid-product but not sodium acrylate, a phase transition reactive system was designed. The product could be stored at low temperature steadily, and could be applied in emulsionpolymerization successfully. It was proved that the temperature is the most important factor; the influence of the catalyst was also important while the reaction time and the amount of the glycidyl chloride relatively affected little. The optimum conditions for synthesizing GA are as follow: temperature 80-85, catalyst 1-3%, solvent 39-69ml, reaction time 4-6h IR spectrum shows that the product is an acrylate with glycidyl groups in its molecule.Extensive studies on the polymerization kinetics about this new binder were carried out. Influential factors such as the propertie... |
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