| Paper historic relics are important historical and cultural heritages. As the years pass, due to various factors, a large number of paper historic relics have been deteriorated, such as being mildewing, yellowing, crumbling, embrittling, contaminating. The current situation of conservation of paper relics is not optimistic.So it is very meaningful to protect them.Chemical reinforcement is one of the important methods to protect the paper, which can effectively prevent the paper from further damage. This paper mainly studied on synthesis of styrene-acrylic emulsion and its application on protection of paper relics. Styrene-acrylic emulsion is a kind of widely used polymer which could obviously improve the mechanical properties of paper, improve the toughness of paper fiber, thicken the fiber of paper, prevent the breakage of fiber and prolong the preservation life of paper. What is more, styrene-acrylic emulsion has good film forming properties, transparency, corrosion resistance, weather resistance and little effect on the appearance of paper. So it is expected to be used for the protection of paper relics in the future.In this paper,with methylmethacrylate(MMA) and styrene(ST) as hard monomers,butyl acrylate(BA) as soft monomer,ammonium persulfate(APS) as initiator, sodium dodecylsulfate(SDS) and alkylphenol polyoxyethylene ether(OP-10)as emulsifiers,sodium bicarbonate as pH buffer, polyvinyl alcohol(PVA) as base fluid,a styrene- acrylate emulsion for protecting paper relic was synthesized.The synthesis conditions wereoptimizedby single factor experiment. We studied different factors(such as emulsifying temperature, emulsifier ratio, dosage of emulsifiers, emulsifying time) on the effect of the quality of pre-emulsion. The effect of different factors(such asratio of soft and hard monomer, hard monomer ratio, dosage of initiator, time for adding monomer pre-emulsion, mass concentration of PVA base, reaction temperature, optimum storage solids content and so on) on the quality of emulsion polymerization product were studied too. The styrene-acrylic emulsion was also applied on the reinforcement of paper and by the characterization of paper, the best application concentration of SAE and drying temperature were determined. We investigatedthe effect of styrene-acrylic emulsion on the aging resistance of paper, different kinds of papers and writing on paper. In order to meet the needs of more paper reinforcement, the styrene-acrylic emulsion, carboxymethyl cellulose and polyvinyl acetate emulsion were mixed and the optimum mixture ratio was determined.The research results showed that the best emulsification condition were: m(OP-10):m(SDS)=1.3:1.0 or 1.0:1.3, emulsifying temperature and time were 50 ℃and 0.5h respectively, w(emulsifier) =1.6%. The best reaction condition were: m(soft monomer):m(hard monomer)=1.0:1.0, m(MMA):m(St)=2.0:1.0, w(emulsifier)=0.41%, w(initiator)=0.38%, m(SDS):m(OP-10)=1.0:1.0, w(PVA base)=4.0%, w(storage solids content)=15.0%, temperature 80.0℃, time for adding monomer pre-emulsion 3.0 h. The emulsion which was synthesized under the mentioned experimental conditions had good quality, low gel rate, high monomer conversion rate, good water resistance performance. And the emulsion could obviously improve the mechanical properties of paper.We applicated the styrene-acrylic emulsion on paper, then through single factor experiment the optimum concentration and the optimum drying temperature(5% and 50℃) were determined respectively. The mechanical properties of paper which were treated under the mentioned conditions were greatly improved and the appearance changes of the paper was within the scope which could not be recognized by naked eye. Through the aging experiment, it was found that the styrene-acrylic emulsion had a good anti-thermal aging performance, good anti-ultraviolet aging performance, and could significantly improve the mechanical properties and aging resistance of the paper.The results showed that the optimum compound ratio of SAE, CMC, PVAc respectively were: m(SAE):m(CMC)=10.0:1.0, m(SAE):m(PVAc)=10.0:2.0, m(SAE):m(CMC):m(PVAc)=10.0:1.0:0.5. The compound emulsion which compounded under the mentioned proportion can meet the needs of different paper reinforcement,which further expanding the scope of the application of styrene-acrylic emulsion on protection of paper relics. |
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