Double-sided Coated Thick High-strength Bamboo Plywood Production Process

With the development of national economy and the improvement of standard of living of people increasingly demand in market for every kind of artificial plywood is larger. But our country lumber resource is relatively lesser and forest overlay rate is only 16.55%, which is far less than the average level of developing country. Therefore national science committee and construct ministry set down and regulate research direction, they think that whether we can use our resourceful bamboo to produce bamboo plywood which meets demand for the industry section of constructing, automobile manufacture, packing, decorating, furniture and container manufacture. It has been more than ten years history since bamboo plywood as new artificial plywood come into market for the first time. It is used for the concrete-mould plywood and the railway motherboard or container motherboard.Bamboo has the short growth cycle, and the rebirth ability is strong. The resource in china is very abundant, therefore the bamboo plywood is full of the developing respect. Presently in the production of bamboo plywood we commonly adopt the cold technology which has some advantages but exists some outstanding shortcomings such as the long yielding period, the low efficiency and the large consumption of water and energy. Therefore some people attempt to adopt the heat technology. But this technology has the phenomena on the surface of product such as the large transformation, the low flatness and brightness, drumming easily and rumple.To solve effectively the shortcoming of the heat technology I prepare to study a kind of mid-temperature phenol formaldehyde adhesive that suits for the heat technology and the heat -pressing method correspondingly. The adhesive can cure rapidly and avail to the demand of mid-temperature curing because of its low curing temperature by the way of elevating the rate of polymerization in PF resin , adjusting the mol-ratio of formaldehyde, NaOH and phenol and also adding a little accelerant. I can determine end-point of its reaction in the course of experiment through controlling the viscosity of resin. After dealing with statistically experimental data I analysis the curing influence of the different factors to PF resin at the 105-115℃,and ascertain the most excellent prescription and yielding craftwork. At last I validate the reliability through repeated experiment. Experiment present that when the mol-ratio of phenol: formaldehyde:NaOH:H2o is the ratio of 1:1.75:0.4:11.5 ,and the quantity of accelerant is fourpercent of the quantity of phenol, the viscosity is 360-420 seconds the resin can cure at the mid-temperature.Bamboo plywood use one or two wooden-boards covering the surface of motherboard , which can solve the problem of milling difficulty because bamboo's rigidity is great. The feasible thickness of wooden-board ought to be 3.0mm and its glue quantity is 100g/m2 or so. The pressure divided to three sections is unloaded. Also technology parameter is decided by experimental analysis. Experiment present that when the heat pressing temperature on the motherboard is 105-115℃,the pressure is 2.8Mpa,and the time holding pressure in high pressing stage equal to 60s/mm.and the rate of moisture in the bamboo motherboard is 12-18% the technical parameter is the most excellent. After milling surface motherboard is plastered with the PF dipped paper that may be one or two ones depending on need. The most excellent technical parameter in term of experiment is heat pressing temperature 140-145℃, the time of heat pressing 3.5-4min, the largest pressure 2.8Mpa,and volatilization content of dipping paper 6-10%.PF resin can cure rapidly at the mid-temperature, as establishes favorable conditions that adopt the heat technology in the production of bamboo plywood. Because heat pressing temperature is low consumption of energy can be decreased, also produce cost can be reduced. Milled motherboard can resolve many problems such as the larger thickness tolerance on the surface of general bamboo plywood presently, the l...