Study On The Dimensional Stability Of Medium Density Fiberboard Produced By Modified Urea-formaldehyde Resin

With the rapid economic development and the improvement of people's living standards in China,the decoration expenditure also increases,which accelerates the rapid development of wood-based panel industry.By the end of 2006,the wood-based panel output had reached 74.29 million m~3,of which medium density fiberboard amounted to 24.67 million m~3 and at present,the productive capacity of fiberboard by dry process has reached 30 million m~3.China has become the first country in the world to produce wood-based panel and medium density fiberboard.Various problems in quality rise with the rapid development of wood-based panel industry For example,there are thickness-welling problems in the use of the medium density fiberboard, which affects its quality and the quality of other related products.On the one hand,it does harm to consumers' interests and causes economic loss.On the other hand,it results in high rate of waste products,a waste of resources and the rise of production costs of the enterprises. It starts with the issue,referring extensively to related information at home and abroad and involving my own ideas and the actual production.It studies and explores he dimensional stability of medium density fiberboard,which applying melamine modified urea-formaldehyde resin in medium density fiberboard.Based on a large number of single factors,repeated experiments,the research shows that with the dosage of adhesion,density and the amount of paraffin increasing,the dimensional stability of medium density fiberboard improves;the change of temperature within a relatively small area,has a small effect on dimensional stability; along with the amount of catalyst,ammonia and hexamethylenamine increasing,the dimensional stability of medium density fiberboard shows a decreasing trend.On the basis of experiments,it analyses the reason why different factors influence the dimensional stability of medium density fiberboard.It also demonstrates the changes of the index of mechanical properties such as IB,MOE and MOR,influenced by different factors.By orthogonal tests,it explores the effect on the dimensional stability of MDF by the hot pressing temperature and the amount of paraffin with their interrelationship.Thereby,it infers the primary and secondary factors influencing dimensional stability in the process of production.Finally,on the basis of experiments above,it comes to the optimum techniques of producing medium density fiberboard.It further verifies the accuracy of the conclusions through testing and provides the reliable basis for application in actual production as reference.