| Lignin is the abundant natural resource only next to cellulose in amount industrial. Lignin is the by product of pulping and paper making, but its recycle ratio is low now. Most of the industrial lignin is discharged with waste water, which not only causes pollution but also squanders resource. The recycle of industrial lignin has great economic, social and environmental benefits. This article has made a study of the application of kraft lignin in articifial plate adhesive in order to impulse the course of the industrialization produce and application of the course.Firstly, after all kinds of methods to characterize derivatives of kraft lignin having been described and discussed, the conclusions were showed as follows: the content of carbon, hydrogen and oxygen was 32.64%, 4.28% and 33.82%, respectively. The content of lignin was 38.86%.And the main structural unit was guaiacolyl.The percentage of main function groups was followed: phenolic hydroxyl was 2.47%, alcoholic hydroxyl was 3.72%, methoxyl was 3.12%.The results were the Mn 773.2 , the Mw is 8739.6 ,the D is 11.303.Secondly, according to the chemical structure characteristics of chemical structure of kraft lignin, chemistry modification was conducted firstly.The most excellent conditions for the modification was that the proportion of kraft lignin and formaldehyde was 3:1, temperature was 80℃, reaction time was 3 hours, pH is 11. The rate of hydroxymethy lignin was 30%.At last, in the paper, low cost and reproducible kraft lignin could be used to replace nonreprod -ucible and noxious formaldehyde in the production of lignin modified urea-formaldehyde resin adhesive. The results show the capability of modified adhesive has reached to the country's standard. When the time , temperature of reaction and lignin amount of modified adhesive is respectively 2.5h, 90℃and 30%, the shearing strength of modified adhesive is higher, the quantity of dissociation formaldehyde is 0.5%. It is lower than urea formaldehyde resin adhesive.
|
PDF Full Text Request