Study On Reducing Water Absorption Of Self-crosslinking Acrylate Emulsion Latex Film

Acrylate emulsion can prepared by emulsion polymerization of monomers such as acrylate,methacrylate,and acrylic acid.Acrylate emulsion has the advantages of simple synthesis,low cost,weather resistance,acid and alkali resistance,and good film formation.It is used in the fields of coatings,chemicals,leather,functional films,medical polymers,and water treatment.When used as a film-forming material,it has poor water resistance and high water absorption,this disadvantage severely limits the application range of acrylate emulsion.In order to expand the application range,it is necessary to increase the water resistance of acrylate emulsion and reduce the water absorption of latex films.In view of this,this paper conducted a study to reduce the water absorption of acrylate emulsion latex film.Firstly,the effect of the composition of emulsion polymerization on the synthesis of low water absorption acrylate latex film on the properties of emulsion and water absorption of latex film was investigated,and the basic formula of emulsion polymerization for preparing low water absorption latex film was determined;On this basis,the type and amount of internal crosslinking agent,the internal crosslinking structure of the latex particles and the effect of the external crosslinking system on the water absorption of the acrylate latex film were investigated.By optimizing the internal crosslinking structure of the latex particles,we determined formula composition and polymerization conditions of low water absorption latex film.Finally,The feasibility of using low molecular weight SMA copolymer saponification as emulsifier to synthesize acrylate emulsion with low water absorption latex film was explored.The main conclusions are as follows:(1)The amount of emulsifier,compound emulsifier ratio,initiator amount,soft and hard monomer ratio,and hydrophobic monomer St content in the composition of the synthetic acrylate emulsion all affect the water absorption of the latex film.Among them,the amount and proportion of composite emulsifier and the amount of hydrophobic monomer have the greatest influence on the water absorption of acrylate latex film.Under the premise of ensuring the stability of the emulsion,reducing the amount of emulsifier,increasing the proportion of non-ionic emulsifier in the composite emulsifier,and increasing the amount of hydrophobic monomer can greatly reduce the water absorption rate of the latex film.(2)The type and amount of internal crosslinking agent of acrylate emulsion and the crosslinking structure of the latex particles have a great influence on the crosslinking degree and water absorption of the latex film.The crosslinking structure of the latex particles is important factor.When DVB is used as the internal crosslinking agent,the dosage is 2% of the monomer,the water absorption of the latex film is the lowest.On this basis,the crosslinking structure of the latex particles was optimized,and it was found that when the crosslinking structure is that the inner crosslinking layer is within the self crosslinking layer and the amount of monomer used in the inner crosslinking layer is 20%,the core-shell structure formed is help to reduce the water absorption rate of the latex film,at this time the minimum water absorption is only 4.24%.(3)The choice of external crosslinking system has a greater impact on the water absorption.The GMA + AA cross-linking system is more suitable as the self-crosslinking system of acrylate emulsion than the AM + AA cross-linking system.When the amount of cross-linking monomer accounts for 2% of the monomer,the performance of the emulsion and latex film is better,and the water absorption is smaller at 4.79%.(4)Alkali saponified low molecular weight SMA copolymer can be used alone as emulsifier for synthetic acrylate emulsion.The acrylate emulsion prepared by using Na OH saponified SMA copolymer as emulsifier has good overall performance,and the latex film has a low water absorption of only 9.52%.