Study On Alkali Lignin Modified As Paper Reinforcing Agent

Now secondary fibers and herbs fibers are broadly used for pulp and paper in paper industry for protecting the environment and reducing the lumber dosage. However, because of those fibers' characteristics, it has been become a burning problem that the paper product made from those fibers has a defect of bad strength and low quality. As is well known, adding reinforcing agent to pulp properly is an effective way to deal with paper strength.The black liquor from chemical pulping industry, in which the solid has 90 percent of the paper industry pollution, is the main pollution source. Now it mainly takes burning way to reclaim alkali wastes, but the value of organic matter as forward recovery is not high as recovery. So the research on alkali lignin enjoys large economic and social value.The paper has researched and discussed the preparation, strengthening effect, composing and strengthening mechanisms of 3 resins, which are modified lignin (ML), modified lignin-beetle (ML-UF) and modified lignin-melamine formaldehyde resin (ML-MF).The basic structural motive of alkali lignin is similar with phenol, containing phenol-carbonyl, alcohol-carbonyl, metonym and other active groups, and it can set off a reaction of carbonyl modification. By modification, modified lignin can react with UF and MF, which have function of strengthening effect, then the product are added to pulp. In pulp, this product can make a structure with fiber and strengthen the strength among fiber, therefore, the strength of paper or paper boxes can be improved.Based on lignin' s structure characteristics, alkali lignin is modified by formaldehyde, then modified lignin is composed of ML-UF, ML-MF with beetle(UF) and melamine formaldehyde resin(MF) and the best conditions of these three reactions are optimized, as follows:①Lignin modification: formaldehyde dosage 6.33 milli-mol per gram lignin, potential of hydrogen(pH) 10.5, reactive temperature 65℃, reactive time 90 minutes;②ML-UF reaction: ML dosage 40%, pH 8.5, reactive temperature 45℃, reactive time 3.5 hours; ③ML-MF reaction: ML dosage 80%, pH 8.5, reactive temperature 45℃, reactive time 3.0 hours.It is shown from applicative experiments of three modified product (ML, ML-UF, ML-MF) : When the variables of pH, reinforcing agent are 4.5 to 5.5,6%, respectively, paper strength is the best, and the added values of paper dry strength are...