【作者】 丁可力；

【导师】 陈瑞英； 王旭；

【作者基本信息】 福建农林大学 ， 林业工程， 2009， 硕士

【摘要】 随着林业加工产业的发展,特别是人造板工业的迅速发展,中密度纤维板产量的增长和使用范围越来越广泛,市场对其各项物理力学性能要求越来越高,特别是对防水性能的要求也越来越高。国内外中密度纤维板行业主要以固体石蜡或熔融石蜡作为防水施加剂,已经难以满足先进的中密度纤维板生产制造工艺的要求。采用乳化石蜡作为防水剂,应用于中密度纤维板的生产,既能提高中密度纤维板的防水性能,又不影响其强度等性能,同时节省石蜡用量降低成本,是中密度纤维板生产企业亟待解决的重要课题之一。对提高中密度纤维板的品质和拓宽应用领域具有重要意义。本课题进行了乳化石蜡防水剂在中密度纤维板生产中的应用研究,比较了熔融石蜡、减少的熔融石蜡和乳化石蜡防水剂的防水效果、力学性能和经济效益;采用三因素三水平正交试验分析,并探讨乳化石蜡对中密度纤维板厚度的影响,得出以下结论:1.采用生产上正常使用熔融石蜡量和直接减少熔融石蜡使用量的对比试验,得出减少熔融石蜡使用量的MDF吸水厚度膨胀率为11.12%,明显高于正常使用量,说明减少熔融石蜡施加量对MDF的吸水厚度膨胀率增加比较大,无法保证MDF的质量。因此,以减少传统熔融石蜡用量降低成本是不可行的。2.通过正交试验和极差分析得出:影响MDF吸水厚度膨胀率的因素,密度为最大,UF施加量其次,石蜡量影响最小;较优工艺参数:密度为800kg/m3,UF施加量为10%,乳化石蜡施加量为1.0%。在一定量范围内,随着乳化石蜡施加量、UF施加量和密度的增加,MDF的吸水厚度膨胀率减小、内结合强度增大。然而当乳化石蜡施加量从1.0%上升到1.3%,MDF的内结合强度反而下降。3.采用优化工艺压制厚度分别为21mm、15mm和6mm的MDF,其吸水厚度膨胀率分别为5.782%、7.0285%和11.307%;国家标准中规定MDF随着厚度减少,允许厚度膨胀率相对指标值增加,说明乳化石蜡作为防水剂用于生产薄、中、厚三种规格的MDF,均符合国家标准要求,是可行的。4.与熔融石蜡相比,乳化石蜡稳定性高,流动性好,颗粒细小,扩散性和均匀性好,在蜡水界面形成具有一定机械强度,使得界面膜的强度增强。因此采用乳化石蜡防水剂来生产MDF时,可减少石蜡用量,既提高MDF防水性能,又能保证力学强度。5.用乳化石蜡防水剂等量替代熔融石蜡防水剂生产MDF,可以节省15%～20%左右的石蜡成本。例如使用1%复合乳化石蜡,MDF的防水剂成本下降了13.5元/ m3。对于年产5万m3的MDF企业,每年可以节约65万元左右。按我国2008年的MDF产量,一年可以节约成本3亿6千多万元。因此采用乳化石蜡防水剂替代熔融石蜡使用,可以降低企业生产成本,提高经济效益。更多还原

【Abstract】 With the development of forestry processing industry, particularly the rapid development of wood-based panel industry, the production of Medium Density Fiberboard (MDF) has increased dramatically and its application is wider and wider. In addition, the market is demanding higher physical and mechanical properties on the MDF, with focus on the waterproof performance. Two kinds of waterproofing additives– solid wax and melted wax, are widely used in the domestic and oversee MDF industry. However, they are increasingly difficult to meet the requirements of advanced manufacturing process. Using emulsion wax as a waterproofing agent in the MDF production not only can improve the waterproof performance without affecting its strength properties, but also can reduce wax usage and costs. Consequently, solving this problem is highly important to the MDF production enterprises, which also has immense implications in improving the quality of MDF and broadening its application areas.The primary purpose of this study is to examine the application of the emulsion wax in the MDF production and to compare the waterproof performance, mechanical properties and economic benefits associated with MDF using three different waxes as waterproofing agent, including melted wax, reduced melted wax and emulsion wax. Three factors (density, the amount of emulsion wax and glue) and three-level orthogonal analysis are used as a means to explore the impacts of emulsion wax on the thickness of MDF. Some principal conclusions are listed below:1.Comparison experiments were conducted to examine the impacts of reducing the amount of melted wax used in the MDF production on the Thickness Swelling (TS) of MDF. The resulted average TS was 11.12% with reduced amount of melted wax usages, which was fairly higher than that of normal amount of melted wax usage. It is evident that directly reducing the amount of melted wax usage in the MDF production has a relative great influence on TS and could not guarantee the quality of MDF. As a result, lower costs could not be achieved by merely reducing the amount of conventional melted wax usage in the MDF production.2.The results of orthogonal test and range analysis indicated that amongst all the factors affecting the MDF TS, the density was greatest, followed by the glue amount, and the amount of wax usage was least. The better process parameters obtained from the experiments were that the density of 800kg/m3, the amount of adhesive applied to 10 % and emulsion wax amount of 1.0%. Within a certain range, as the amount of emulsion wax and glue and density increased, the TS decreased and the internal bonding strength (IB) increased. However, when the amount of emulsion wax was increased from 1.0% to 1.3%, IB began to decline.3.Using the optimizing process obtained by the orthogonal experiments to produce the MDF with the thickness of 21mm, 15mm, and 6mm, The TS respectively were 5.782%, 7.0285% and 11.307%.As national standards, with the reduce of thicknes of MDF,allow have a high Thickness Swelling .The results showed that using emulsion wax as waterproofing agent for the production of thin, medium, thick three kinds MDF were in line with national standards for MDF and was feasible.4. Compared with the melted wax, emulsion wax has high stability, good fluidity, small particles, good diffusion and homogeneity and has a certain mechanical strength in the wax-water interface making the intensity of interfacial film increase. Therefore, when using the emulsion wax as waterproofing agent to produce MDF, could both reduce the amount of wax and improved the waterproof performance and guaranteed the strength to meet the practical application.5. Using the same amount of emulsion wax as a substitute to melted wax in the MDF production, the costs can be reduced by 15-20%. For example, if 1% of compound emulsion wax was used as waterproofing agent, the costs could be reduced by 13.5 yuan / m3. For a MDF producer with the annual capacity of 50000 m3, the costs saved are around 650000 yuan. Given the total MDF production of 2008 in China, the total costs saved can reach 360 million yuan for one year. As a result, using emulsion wax instead of melted wax as a waterproofing agent in the MDF production can reduce production costs as well as increase economic efficiency.更多还原