Preparation Of The Water-borne, Low-temperature Curable Polyacrylate Latex And Its Application In The Textile

In this paper, water-borne and low-temperature curable polyacrylate (PA) latexes (non-formaldehyde, low formaldehyde) were synthesized through the pre-crosslinking technique based on environmental friendly profile. Such PA latexes were applied in the pigment printings and fabric coatings. There is no-AOX pollution when the latexes were being prepared and used. In this study the suitable cross-linkages were already introduced into the copolymers in the polymerization stage. When the latexes were applied to the web and dried, strong enough films were formed. And the curing process was omitted. This was of great importance both in economical and environmental aspects.The non-formaldehyde water-borne PA latex was developed by definitely introducing cross-linkages in polymer chains with a polyfunctional crosslinking monomer A The low-formaldehyde PA latex was prepared based on the pre-crosslinking technique by the addition of a limited amount of N-methylolacrylamide (NMA) in the reaction system. Interpenetrating networks were formed when the low-formaldehyde film was cured at a suitable temperature. Such a film would possess excellent performances.In this paper, the action mode of NMA in the traditional polyacrylate emulsions was studied by extracting the traditional self-curable PA latex film before curing and comparing the properties of two kinds of model latices A and B. Where model A was prepared according to the traditional self-curable PA latex and the model B was a blend of polyacrylates emulsion and an aqueous solution of poly-NMA. The total proportions of the ingredients were adjusted just the same as of model A. The influences of monomers, the dosages of crosslinking monomer A and emulsifier etc. were investigated. The film-forming properties and the mechanical properties, solvent resistance, Tg, surface morphology of polymer film, the basic properties of latex were also studied extensively. Performance of latex used as pigment printing binder, fabric coating on cotton and nylon fabrics were evaluated. The only weakness of the non-formaldehyde product could be decreased or even eliminated by core-shell polymerization technique.The results obtained were as follows: 1. The conventional emulsion polymerization of acrylic monomers with N-methylolacrylamide (NMA) couldn't produce real copolymers because of the large water solubility of NMA. A soluble PNMA was formed in the aqueous phase, and the polymer formed was in deed a blend of polyacrylates emulsion and poly-NMA solution. On curing, the -NCHaOH groups of PNMA film would condense with each other to form a network of PNMA in which the PA molecular long chains were be "tightened" in bundles, or be confined in the meshes of the networks.2. During the developing process of the low-temperature curable, non-formaldehyde PA latices, the monomers were chosen based on the organic / inorganic ratios, and the co-polymerization reactivity ratios. The effects of crosslinking monomer A and B were also compared. The emulsifiers used were compounded systems composed of anionic and nonionic surfactants. Other conditions such as initiator, reaction temperature, and the amount of MAAalso influenced the properties of the latices.3. In preparation of the low-formaldehyde PA latex, a certain amount of N-methylolacrylamide was added in the reaction system to introduce the interpenetrating networks into the film by curing at a suitable temperature. And the performance of the film was excellent. The formaldehyde releasing from the coated fabric was below 30ppm.4. The key point of the low temperature curable, non-formaldehyde PA latex was the introduction of crosslinkage by addition the monomer A, a multifunctional monomer, and the extent of pre-crosslinking. The results showed that the products had excellent properties when the content of crosslinking monomer A in non-formaldehyde latex lay between 5% to 6%.5. The particle size of latex was mainly concentrated in the range of 0.3~0.65 n m, and the particle size distribution was narrow, therefor...