Study On The Synthesis And Application Of Modified Acrylate Copolymer Surface Sizing

In recent years,a higher requirement for paper quality,especially for paper surface properties has been put with the rapid development of printing and paper industry.A kind of efficient surface sizing agent was required to solve the complex wet end chemistry problems caused by paper internal sizing,and improve the paper properties.The research and application of synthetic polymer surface sizing agents,one important type of which is acrylate copolymer emulsion.has been received extensive attentions for excellent performances and higher sheet retention.There were the problems in common styrene-acrylic emulsion,such as low hardness,bad film forming properties,low drying efficiency,serious Summer back-stick and so on.In this paper,the modification of acrylate emulsion was sudied in many reaction systems by particle designing and introduction of functional monomer.In organic/inorganic composite system,the influnce of the types and amounts of emulsifiers,silica sol dosage,reaction temperature,reaction time on the acrylate emulsion properties.The optimal synthesis conditions were obtained that the amount of KL-100,silica sol and initiator APS was 6%,1%and 0.7%of the monomer,respectively,Hard and soft monomer ratio was 1:1,reaction temperature was 75?,reaction time was 3 h,In epoxy modified system,the four facters of AA dosage,ECH amount,reaction temperature and time were researched.Its optimum conditions were as follows:reaction temperature of 75?,reaction time 2 h,the amount of emulsifier of 6%,holding time 1 h,initiator dosage of 1%,AA and ECH total of 2%(1:1),hard and soft monomer ratio of 1:1,the APS,sodium bicarbonate and pentanol.dosage of 0.7%,0.6%and 0.5%,respectively.The influnce factors of emulsifier amount,hard and soft monomer ratio,functional monomer dosage,cross linking pH,reaction time and temperature on the properties of acrylic emulsion were studied in ketone hydrazine inner crosslinking system.hard and soft monomer ratio was 3:7,reaction temperature was 70 ?,nuclear reaction time was 5 h,the shell reaction time was 2 h,the amount of emulsifier was 6%,holding time was 1h,cross linking pH was 9,functional monomer dosage was 3%,initiator dosage was 1%.These were optimum reaction conditions.In this paper,the properties and the sizing effect on paper of emulsion synthetized in organic/inorganic composite system,epoxy modified system and ketone hydrazine inner crosslinking system were compared.The results showed that the properties and sizing effect of emulsion prepared in ketone hydrazine inner crosslinking system were much better than that in organic/inorganic composite system and epoxy modified system.of which solid content was 300%,the conversion rate was up to 99%,and the gel rate was only 0.04%,the cobb60 and gloss of the base paper after surface sizing was 4 and 24(75°),respectiely.Finally,a preliminary analysis of the pattern and factors in film-forming process was conducted.The results showed that all of the glass transition temperature of the emulsion polymer,the minimum film forming temperature,particle size,solid content and the paper characteristics have an important impact on emulsion film-forming and film natures.