Research About The Influence From Laccase Pretreatment To The Sizing Amount Of Artificial Board

Formaldehyde is one of main pollutants of indoor environment. Sources of formaldehyde are widely. The main source of releasing is the cementing material of artificial board. To develop a production process of environmental protection artificial board is one of the most important development trend of international wood industry. Enzyme treatment is one of the most important ways to product process of environmental protection artificial board.The laccase secreted by white rot fungi is one of the main enzyme treatment methods to wood materials. Some research results have been published about the artificial board been made up with purified laccase treated wood materials. But using unpurified laccase treat wood materials has been rarely reported. The main contents of this subject are the optimization of the culture of white rot fungi and mass culture and make artificial board with unpurified laccase treated wood materials.Processing methods of optimization of the culture of white rot fungi are:change inoculation method to culture white rot fungus; use magnetic stirrer and constant temperature box instead of constant temperature culture oscillator. The method of batch culture white rot fungus to product laccase is to expand the culture vessel.(1) Change the inoculation way to culture white rot fungus has a certain influence to success rate. And this can short the time to raise the laccase activity to the peak rate. It can short 2 days to raise the laccase activity to the peak rate that using the white rot fungi mycelium pellet to inoculate instead of colony tablets. And the success rate raises to 96%.(2) Using the new inoculation way to culture white rot fungus and at the same time make a magnetic stirrer as a new culturing instrument instead of thermostatic culture box. Under the temperature of 25 DEG C, the speed of 170r/min culture conditions, and using asymmetric rotor, white rot fungi can produce high activity laccase of which the peak rate is 100U/mL higher than using the original method. Using this culture method, the success rate raises to 96%, and it can short 2 days to raise the laccase activity to the peak rate. And also, it can provide a simple operation, low energy consumption method to mass culture white rot fugus.(3) Culturing white rot fungus with magnetic stirrer and mycelium pellet inoculation way can produce the laccase of 450U/mL peak rate and the mycelium pellets have uniform size. When the culture vessel expands to 1000mL, the laccase solution production yield is 4 times more than original method production yield.(4) Under the same quantity of glue and hot press condition, the artificial board made up with laccase treated wood materials has better mechanical properties than the artificial board made up with untreated wood materials. This result shows that the wood materials treated by laccase themselves are adhesive. Under the same hot press condition, the mechanical properties of untreated medium density fiberboard can not reach the national standard when the quantity of glue is lower than 12%, and when the quantity of glue is 10% and 12% the mechanical properties of treated medium density fiberboards is still higher than national standard. When the quantity of glue dive down to 8%, the modulus of elasticity and static bending strength can still reach the national standard, and the internal bond strength is close to national standard.