Development of lightweight wood-cement composite board using microballoon of fine pulvernized volcanic glass(micro-Shirasu-balloons)

为了制造轻质木水泥复合板，将微白松气球的各个部分混合到水泥粘合刨花板中。预计气球的加入不仅会使它们更轻，而且还会改善一些性能。因为气球是火山玻璃细粉化后的燃烧产物，具有极低密度、低导热性、低吸湿性、高熔点、高耐热性和不燃性。试验板材的配比为：水泥/木屑比（wood ratio）： 2.0、2.5气球/水泥比（Balloon ratio）： 0-0.5目标密度：0.6-1.2板材尺寸：350x350x15mm。通过对所制板材的物理试验和观察，总结出以下几点：(1)在较高的气球比下，木材比为2.5的高密度板材无法控制目标厚度。(2)板材表面状况明显改善，尤其是低密度板材。(3)在密度为0.8及以上的板材中，当气球比为0.1和0.2时，其弯曲性能和内粘接质量都得到了改善。即使是密度为0.8的板材，其抗弯强度也符合JIS《高密度水泥结合刨花板》的要求。但是，当气球比小于0.2时，这些性能下降。(4)在球囊比大于0.1的情况下，浸渍24h后板材的厚度膨胀明显减小，特别是密度较高的板材。(5)当球囊比为0.3及以上时，密度为1.2的板材导热系数降低了5 ~ 10个百分点，当球囊比为0.2及以上时，密度为1.0和0.8的板材导热系数降低了5 ~ 10个百分点。(6)所有试验板材均具有较高的耐火性能，符合JIS内饰面材料不燃性等级2的要求。

In order to make lightweight wood-cement composite board, various parts of micro-Shirasu-balloon were mixed into cement-bonded particleboard. It was expected that the addition of the balloon would not only make them lighter, but also improve some properties. Because the balloon is the burning product from fine pulvernized volcanic glass and possesses very low density, low thermal conductivity, low hygroscopicity, highly melting point, highly heat resistance and incombustibility. Boards for test were made at the mixture ratio under the conditions as follows :Cement/wood chip ratio(Wood ratio) : 2.0,2.5Balloon/cement ratio(Balloon ratio) : 0-0.5Target density : 0.6-1.2 Board size : 350x350x15mmResults were summarized from physical tests and observation of the boards made as follows :(1)Target thickness could not be controlled in higher density board of the wood ratio of 2.5 at higher Balloon ratio.(2)Surface condition of the boards was improved remarkably, especially in lower density boards.(3)Bending properties and internal bond quality were improved in the boards of the density of 0.8 and more at lower ballon ratio of 0.1 and 0.2. Even the board with the density of 0.8 met the requirements of JIS of High Density Cement-Bonded Particleboard in bending strength. But, those properties decreased in the boards of the balloon ratio less than 0.2.(4)Thickness swelling after 24h soaking test was reduced remarkably in the boards at the balloon ratio of 0.1 and more, especially in higher density boards.(5)Five to ten percentile reduction of thermal conductivity was recognized in the boards of the density of 1.2 at the balloon ratio 0.3 and more, and of the density of 1.0 and 0.8 at the balloon ratio 0.2 and more.(6)All of the boards for test showed high fire resistance and met the requirements of the JIS incombustibility grade 2 of Internal Finish Material.