共查询到19条相似文献，搜索用时 187 毫秒
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刨花板板坯表面增湿处理—缩短热压周期的有效途径 总被引：1，自引：0，他引：1
本文阐明，刨花板板坯表面增湿是缩短热压周期的有效途径及其原理，影响增湿效果的主要因素是热压板温度、增湿量、增湿层厚度比。 相似文献
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脲醛胶热压时的预固化常造成压制后毛板表面的碎料剥落，需加大砂光量去除预固化层方能使成品板符合标准。为解决使用脲醛胶的板材在热压过程中的预固化问题，北京林业大学开发研制了ＬＧＰ人造板板坯表面处理剂。ＬＧＰ表面处理剂为无毒、无刺激性、无腐蚀性粉体，使用时配制成液体，喷施于板坯表面及垫板上。ＬＧＰ表面处理剂价格低廉，据测算，每张４×８（英尺）板的处理费仅需０．１５元。１９９９年８月北京林业大学与天水币小陇山林业实验局纤维板厂在该厂进行了生产性试验。试验结果证实了：（１）ＬＧＰ表面处理剂能减轻预固化现象… 相似文献
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喷蒸真空热压水溶性酚醛胶杨木大片刨花板 总被引：3，自引：0，他引：3
我国防水人造板生产目前普遍采用酚醛树脂胶（PF），热压周期长，生产效率低。笔者采用南京林业大学饱和蒸汽喷蒸试验压机，压制水溶性PF胶杨木大片刨花板。结果表明，采用喷蒸真空热压（SIVP）技术，热压时间可缩短到传统热压的35％左右；板的吸水厚度膨胀率（TS）缩小33％；在相同施胶量下，板的内结合强度（IB）提高的15％，同时甲醛释放量降低约24％；但板的抗弯性能有较大幅度的下降；此外，板材芯层最低密度值比传统热压的板增高，断面密度分布趋于均匀。 相似文献
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复合型脲醛树脂固化剂的初步研制 总被引：1，自引：0，他引：1
报道一种多组分复合型固化剂研制的初步结果。该复合型固化剂除ＮＨ４Ｃｌ组分外，尚含有木材表面活化剂Ａ、甲醛清除剂Ｂ和其它助剂Ｃ。其中表面活化剂Ａ通过提高木材与胶粘剂之间的交联程度而提高胶合强度，同时该表面活化剂也有助于提高树脂固化速度；甲醛清除剂Ｂ可进一步降低板材甲醛释放量；助剂Ｃ可提高热压过程中板坯芯层温度，这对提高热压效率和提高胶粘剂固化程度均有积极影响。 相似文献
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研究刨花板板坯表面增湿处理对其热压过程中表面、中心层温度变化的影响,比较分析不同板材密度和厚度、板坯含水率及热压温度等工艺条件下,板坯中心层的升温速度随其坯表面喷水量的变化曲线,总结出板坯表面增湿处理对其中心层温度的影响规律. 相似文献
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柔性电热板加热摞式热压工艺的研究与实践 总被引：1，自引：1，他引：0
在单层大开档压机中，将数块特殊制作的柔性电加热板按一定方式直接置于成摞堆放的板坯中对板坯进行加热加压。板坯为多层胶合板或细木工板。几年的研究与实践证明：与目前通常的刚性压板热压相比，板坯压缩率较小（低于４％），能源消耗也较低，电耗为３０～５０ｋＷｈ／ｍ３。在单板含水率为１４％～１８％的条件下，仍然有十分可靠的胶合，胶合强度均大于１．２ＭＰａ。 相似文献
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中纤板压力-板坯厚度曲线的研究与应用探讨 总被引：1，自引：1，他引：1
进行了常温下的中纤板板坯压缩过程的压力-板坯厚度曲线初步研究,得出板坯厚度与面压呈幂函数关系的试 验结论。探讨了试验曲线在中纤板多层压机液压系统设计中的应用。 相似文献
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结合实例，本文介绍了中纤板铺装机的结构和工作原理，分析了影响板坯铺质量的因素，对如何有效控制板坯的铺装质量进行了探讨。 相似文献
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The effects of using 100% black spruce (Picea mariana) bark fibers as core layer material accounting for up to 70% of the board and its resin content (between 6 and 10%) on the
properties of three-layer medium-density fiberboard (MDF) were investigated using a full factorial experimental design with
two independent variables and three levels. Five response variables, namely internal bond strength, modulus of rupture, modulus
of elasticity, thickness swelling and water absorption were statistically analyzed using a response surface methodology and
two-way analysis of variance. The effects of the proportion of core layer (bark fibers) and its resin content on panel properties
were significant. All properties studied were positively affected by increasing core layer resin content. The effects of the
proportion of core layer (bark fibers) on mechanical properties and water absorption were negative, but positive on thickness
swelling. Simultaneous optimization of panel properties indicated that at a density of 850 kg/m3, a three-layer MDF with a core layer resin content of 6.5%, a face resin content of 12 and 60% of core layer proportion (spruce
bark fibers) would satisfy the minimum requirements of ANSI standard for 130-grade MDF. Overall, black spruce bark, a major
residue source in the Eastern Canada, should be considered as a supplemental furnish for the core layer materials of a three-layer
MDF. 相似文献
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Medium-density fibreboard (MDF) was produced from fibres treated with maleated polypropylene wax. The objectives of this study
were to improve the dimensional stability of MDF panels by this treatment; to observe the maleated polypropylene wax distribution
within the MDF panels using conventional fluorescence microscopy; and to determine the effects of the treatment on the mechanical
properties and vertical density profile of the panels. MDF panels were produced from two resin types (urea-formaldehyde and
melamine-urea-formaldehyde) and three maleated polypropylene wax contents (0, 3 and 5%). Photomicrographs show that maleated
polypropylene wax forms agglomerates within the MDF panels which is an evidence of its poor distribution in our experimental
conditions. Our results show an important reduction on thickness swelling and water absorption after water soaking for panels
produced from treated fibres. Linear expansion and contraction in adsorption and desorption conditions between 80 and 50%
relative humidity increased following fibre treatment. However, thickness swelling and shrinkage in similar conditions showed
an important reduction following fibre treatment. The fibre treatment did not have negative effects on the mechanical properties
or the vertical density profile of MDF panels. The modulus of rupture and modulus of elasticity in bending were increased
by the treatment independently of maleated polypropylene wax content. The internal bond strength increased following the addition
of 5% maleated polypropylene wax content. 相似文献
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The purpose of this study was to evaluate compression and swelling characteristics of individual furnish elements sampled
through the thickness of lab panels pressed without resin. Commercial southern pine OSB furnish was used to press resinless
mats so individual flakes could be removed from the panel after pressing and evaluated for compression behavior. 19 flake
sets, each set consisting of 15 southern pine flakes with 0.65% wax, were marked and measured for thickness and mass. One
set of marked flakes was randomly distributed in one layer of a mat which consisted of 19 total layers; each of the 19 layers
had 15 marked flakes randomly distributed in the layer. After hot pressing each marked flake was removed from the mat. After
achieving equilibrium at 35%, 65% and 98% relative humidity, each flake was again remeasured for thickness and mass. Experimental
results include flake compaction ratio and its distribution through the mat thickness, flake thickness swelling under different
RH environments, compaction ratio-thickness swelling relationship as well as individual flake compaction ratio and thickness
swelling variations. Comparison is made to adsorption/desorption behavior of pressed flakes. Flakes from surface layers exhibited
compression of 25 to 37%, about double that of flakes in core layers. As expected, flakes from surface layers showed much
greater thickness swell than core flakes and the response was accentuated with higher EMC conditions.
Received April 26 1999 相似文献
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在中纤板板坯压缩过程的压力-板坯厚度曲线初步研究的基础上,对多层中纤板热压机的液压系统电机-油泵配置方案进行了计算比较,提出了新的设计方案。 相似文献
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研究了加速老化试验对经不同装饰后的脲醛胶中纤板物理力学性能的影响.结果表明,未经装饰的中纤板经加速老化处理后力学强度降低较快,吸水厚度膨胀率明显增大.选用的4种装饰中纤板中,三聚氰胺板的力学性能降低最大,油漆板耐久性能最好. 相似文献