Synthesis Of Self-crosslinking Acrylate Emulsion And Its Self-crosslinking Reaction During Film Formation

Self-crosslinking acrylate emulsions have been widely used because of their excellent film-forming properties and ease of use,therefore,study on various self-crosslinking systems has been a hot topic in this field.The most widely used self-crosslinking systems are N-methylol acrylamide(NMA),N-hydroxyethyl acrylamide(HEAA)and diacetone acrylamide(DAAM)/adipic acid dihydrazide(ADH)three kinds of systems.For NMA and HEAA,some literatures reported that they were high-temperature self-crosslinking systems,while some literatures used them at room temperature,and there are few reports on crosslinking curing conditions of them,the differences in the reaction activity between them have not been reported so far.DAAM/ADH system was mostly used as an ambient temperature self-crosslinking system,but the cross-linking activity and the process of film formation is rarely reported.Herein,in this paper,NMA,HEAA and DAAM/ADH were used to synthesize three kinds of self-crosslinking acrylate emulsions.The effect of cross-linking monomer content on performance of the emulsions and the latex films,and the effect of the film-forming condition on the performance of the latex films were investigated.The main work is as follows.1.A series of emulsions with NMA contents varied from 0 to 5%were synthesized.The effect of NMA content on the properties of emulsions and the latex films,the effect of dodecanethiol on the internal cross-linking reaction of emulsion polymerization,and the effect of heat treatment on the properties of latex films were studied.It was found that NMA has been partially cross-linked during the emulsion polymerization process,and remaining NMA will continue to take part crosslinking after high temperature treatment.Introduction of a certain amount of chain transfer agent dodecanethiol can effectively prevent the occurrence of internal cross-linking.Therefore,NMA is a high-temperature cross-linking monomer,cross-linking at room temperature originates from the internal cross-linking during emulsion polymerization.2.A series of emulsions with HEAA contents varied from 0 to 3%were synthesized.The effect of HEAA content on the properties of emulsions and the relative latex films,and the effect of heat treatment temperature on the properties of latex films were studied.It was found that HEAA-based emulsions does not crosslink during the emulsion polymerization and at room temperature.HEAA is a high-temperature cross-linking monomer.3.A series of emulsions with DAAM contents varied from 0 to 5%were prepared.Effect of DAAM and ADH content on the properties of the emulsions and the latex films,the effect of heat treatment temperature on the cross-linking reaction activity and the properties of latex films were studied,and the film formation process of emulsion was investigated.It was found that DAAM/ADH is a low-temperature cross-linking system,and has high cross-linking reactivity even at-20?.The activity of the cross-linking reaction increases with the temperature of the film formation increasing.