Preparation Of Surface Active And Hydrophobically Associating Type Of DMDAAC Polymer And Its Application In Paper Sizing Process

Alkenyl Succinic Anhydride (ASA) is an important paper sizing agent. The conventional emulsifiers of ASA have many drawbacks such as high cost or bad emulsifying ability. In the dissertation, a DMDAAC copolymer both have hydrophobically associating property and prominent surface activity, is designed and synthesized based on DMDAAC polymer, and successfully used in paper sizing process as emulsifier of ASA. The utilization covered many drawbacks related to conventional ASA emulsifier, and widen the application fields of hydrophobically associating water soluble polymers meanwhile.The target polymer is named as PDAMM and is copolymerized by DMDAAC, acrylamide (AM), maleic di-ester type of Gemini surfactant (MDE), hydrophobic monomer butyl methacrylate (MBA) or octyl methacrylate (MOA). MDE used both as the solubilization aid of MBA or MOA, taking place of conventional surfactant, and as a monomer. Suitable methods are adopted in structure characterization of PDAMM. PDAMM has two glass transition temperature (Tg), such as 198.57℃and 120.98℃, which shows it have a block structure.Various influencing factors during the preparation of PDAMM are studied. The conversion rate are increased by improving of the initial concentration of the initiator and the reaction temperature, decreased by improving of the initial concentration of DMDAAC, MDE and MBA (or MOA); the cationic grade are increased by improving of the reaction temperature, the initial concentration of the initiator and DMDAAC, decreased by improving of the initial concentration of MDE and MBA (or MOA); the intrinsic viscosity of the polymer shows a trend of rising first and falling afterward by improving of the initial concentration of the initiator, and decreased by improving of the reaction temperature, the initial concentration of DMDAAC, MDE and MBA (or MOA).Influence of PDAMM's structure to its hydrophobically associating property and surface activity are studied. Hydrophobically associating property is enhanced by increasing of content and hydrophobic property of hydrophobic monomer and intrinsic viscosity of the polymer when hydrophobic monomer is under its saturate solubilizing amount and PDAMM have good water soluble property. PDAMM has a prominent surface activity. The apparent surface tention of PDAMM solution is affected by its hydrophobically associating property, and has a minimum value at the critical association concentration, such as 45.04mN/m (25℃).Influence of PDAMM's structure to its property of emulsifying ASA is studied. When ASA concentration is 0.50%, ASA latex emulsified by PDAM (DMDAAC- AM-MDE copolymer) breaks in 30 minutes, while ASA latex emulsified by PDAMM (MBA content in PDAMM is 2.00%) remains unbroken in 15 hours. It is proved that the hydrophobic groups cause the main hydrophilic chain of PDAMM to migrate toward and wrap ASA particles, so that the stability of ASA latex is enhanced.ASA emulsifier PDAMM-4N is carried out by optimizing according to the emulsion capability and the sizing effects. PDAMM-4N have monomers contents of DMDAAC = 70.00%, AM = 18.00%, MDE = 10.00%, MBA = 2.00%, and has intrinsic viscosity value of around 0.40 dL/g. The equivalent particle size, radium size distribution and stabilities of ASA latex prepared by PDAMM-4N are all meet the sizing requests.Application technology of ASA/PDAMM-4N latex is studied. Suitable sizing conditions are: ASA is emulsified with the ratio of 1:1 to PDAMM-4N, retention aid system is composed of 1% cationic starch and 0.02% cationic polyacrylamide, filling amount of CaCO₃ is no higher than 25%, drying temperature is 100-105℃, sizing pH is between 6-8. Besides, ASA/PDAMM-4N latex can be used under a high sheering condition and within a broad range of water rigidity. ASA/PDAMM-4N latex can meet the industrial application requests, sizing with it cost 39.14 Chinese Yuan, lower than that of AKD, another commonly used neutral sizing agent.An ASA sizing model is firstly proposed. When only ASA dosage w is concerned, the modelhas a simplified expression of t =1/a-b·w, the related coefficients is 0.9788, and the meanabsolute deviation is 13.48%. When only fix quantity G is concerned, the model has a simplifiedexpression of t =G²/m-n·G, the related coefficients is 0.9932, and the mean absolute deviationis 11.12%.