Study On Paper Fiber Modification With Enzyme

China paper industry is meeting problems such as resource deprivation, energy shortage and pollution severity. Increasing waste paper (secondary fiber) can relieve the factors that restrict the development of China paper.But the pulp quality can decrease in the course of waste paper recycle. The pulp strength and drainage can decline with the recycle times.Pick strength is also obvious during print with the improment of high yield pulp and fastingrow hardwood in the pulp furnish. Enzymes is an environment-friendly, effective and green catalyst and has been applied in the papermaking industry wider and wider. The thesis focuses on the research of the modification of waste corrugated cardboard with biological enzyme, the removement stickies of deink news pulp with laccase/xylanase and the modification of APMP high yield pulp and hardwood.In the meantime, the modification mechanism of enzyme treating fiber is discussed. Drawing conclusions as following by research:1.Laccase/xylanase system(LXS), laccase/mediator system (LMS) and recombination xylanase can increase the paper strength of waste corrugated cardboard. Laccase' effect is better than sylanase'.In contrast with the reference, tensile strength index,ring compression index and wet tensile strength increase respectively 37.53%,23.86% and 50.35% with lOIU/g LXS treating waste paper. It proves that LXS can play the same modification role as LMS when it treats waste pulp. LXS can replace the complex and expensive LMS to treat pulp.2.The refine properties of pulps improve when they are treated with laccase/xylanase system(LXS), laccase/mediator system (LMS) or recombination xylanase.The refine effect with LXS is better than with X. It can save the 25% refine energy when the pulp treated with LXS gets the same refine degree 560SR. Enzyme can improve the drainage property of pulp and the recombination xylanase is superior to laccase/xylanase.3. Laccase/xylanase system(LXS) can remove effectively the stickies in the deink news pulp.Compared witu the virgin pulp, the stickies content respectively decrease 51.91% and 68.43% when the deink news pulp is treated with LXS and LXS+E.It can reduce the load of removement stickies in the latter process.4.LXS can effectively remove the lignin on the surface of fiber and improve the surface strength of paper when it is used to modify the hardwood or APMP.The water resistant ability of paper improves when pulp is treated with xylanase.The key factors affecting the surface strength of paper are temperature and pH. The final regression equation is Y=28.41-9.323A+1.823B. (A-pH; B-temperature)5.The free radical consistency, the advance angle of contact, the crystalline, the infrared spectrum and electronic microscope photos are analysed after the secondary fibers were treated with LXS. It explains why LXS and xylanase can improve the physical strength, the refine and drainage prpperties of pulp in theory.