Study On Effect And Mechanism Of Enhancement For AKD Surface Sizing

Alkyl ketene dimer (AKD) as a type of neutral and alkali sizing agent has been widely applied to paper production. AKD sizing has a slow curing in the first, while sized paper does not reach the final sizing degree, which need be ready for a long time to reach. Therefore, the reaction between the fibers and AKD is slow, and a long curing time is the main problem. Therefore, considing adding enhancement agent is one of the hot spots for paper researchers to solve the problem. In this connection, the advantages and disadvantages of enhancement agent on AKD application and development trend is discussed, then preliminary investigated on the mechanism of singzing synergism.Different enhancement agents has influence to AKD sizing are major researched in this paper. First, reacted in alkaline condition, then a cross-link and the other enhancement agent match with AKD for paper surface sizing.Then, emphasize investigated on the effects of enhancement type, dry temperature, dry time and sized paper curing time and so on for AKD sizing, furthermore optimizes the technology of enhancement and AKD surface sizing. Through study, found the optimum dosage of guar gum cross-link is 0.02%, PDMDAAC is 0.03 %, and the best ratio of PDMDAAC:Al₂(SO₄)₃ is 3:1, dry temperature and time are 120℃and 5min, therefore the sizing effect is best. Guar gum cross-link and PDMDAAC can enhance the AKD cured, which has a remarkable effect, the curing rate of sized paper increases of 64.2%, the final sizing degree is increased 44.7%, and reaches the final sizing degrees after 2h, the curing time of AKD is shortened significantly. In addition, induces the cost of AKD sizing to 62.5%.Adopt PAE and PAM as enhancement to AKD internal sizing, which can promote the hysteresis of AKD curing, sized paper effect has improved, and could achieve the end degree in four days, shortens the curing time.however, PAE has a superior sizing effect than PAM.Compration with styrene, AKD adding enhancement, its been a considerable effect with styrene, even better. Then, compration of the cost, styrene's price is higher than AKD, so use AKD sizing can reduce the cost and achieve the ideal results. However, AKD sized paper, both internal; purface or double sizing, does not have a ideal waterproof effect to hot water.To explore the mechanism of enhancement agent to enhance AKD sizing, this article research and analysis in different pieces of sized paper: with SEM study on the surface structure of sized paper before and after curing, which explained the addition of enhancement in AKD has a more spray than ordinary AKD and the fibers arranges orderly, combined closely. Adding enhancement in AKD, the contact angle of paper increased, the effect of waterproof is improved, the guar gum cross-link and PDMDAAC are together as the enhancement, whose resistance to water is best. Infrared spectra showes that, adding enhancement in the AKD, the bond of lactone ring ester is opened, and AKD properties is more stable, at the same time, a celery in addition to guar gum cross-link and PDMDAAC at the basis on the effect of the better than individual adding guar gum cross-link or PDMDAAC, then reveals that the resistance to water in the experimental results in accord.