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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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喷蒸真空热压刨花板板坯内部的温度场特性 总被引:6,自引:0,他引:6
研究了喷蒸真空热压杨木大片刨花板坯内部的温度分布特征。实验结果表明,平行于热压板的板坯中心平面内的温度分布比较均匀,沿板坯厚度方向各点的温度分布差异较大。在喷蒸真空热压过程中,板坯内部的温度上升速率比传统热压快得多。 相似文献
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喷蒸热压新工艺技术及其在国内外人造板工业中的应用开发 总被引:2,自引:0,他引:2
喷蒸热压技术是近10余年来国际上发展起来的一种人造板生产新工艺,是当代热传导技术、计算机控制技术综合应用于人造板工业的高新技术成果。国外已有利用这种技术压制刨花板、定向结构板、中密度纤维板和一些非木质人造板的成功范例;国内也有一些厂家和院校正在研究和试制喷蒸热压机,并取得了初步的成绩。它的推广应用必将对我国人造板工业的发展起到积极的作用。 相似文献
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1 项目简介该项目是在多年喷蒸-真空热压技术研究的基础上和实施国家林业局科技成果推广项目"厚型中密度纤维板制造技术"中形成的,由南京林业大学和福建龙岩紫金集团永定紫金木业有限公司共同完成.项目针对目前国内缺少厚型中密度纤维板产品及制造技术,重点研究喷蒸-真空热压工艺、蒸汽喷射及真空抽吸系统以及厚型中密度纤维板后期加工技术三个核心问题,研究制造厚型中密度纤维板的最佳工艺参数,通过实验室试验和工业化生产试验,获得自主知识产权,形成了有自己特色的厚型中密度纤维板成套技术(包括工艺和设备),并在工业化生产中推广应用.该项技术可大幅度缩短生产时间,节省能耗,降低成本;产品及制造技术填补国内空白. 相似文献
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人造板喷蒸热压工艺是近年来研究开发的一种新型热压工艺,其热压性能显著优于普通热压工艺。介绍了人造板喷蒸热压技术原理、方法以及喷蒸热压工艺的研究进展,并对喷蒸热压工艺的研究方向提出了一些看法。 相似文献
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喷蒸及真空处理装置是南京林业大学拥有的实用新型专利技术(专利号ZL99229141.0)。该装置具有可进行表面、侧面喷蒸及真空处理等特点,其结构合理、功能多、性能可靠、操作方便。因此,我们利用该装置对本公司人造板分厂的部分热压机进行了技术改造。1 改造前热压机存在的问题1.1 热压超厚板(材)对生产效率及其质量的影响 目前,生产人造板使用的热压机基本上都采用传统的饱和蒸汽作介质加热,受热压的板(材)坯是通过热压板接触传导方式加热的。板(材)坯基本上 相似文献
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刘恩永 《林业机械与木工设备》2002,30(8):36-37
蒸汽喷蒸热压是近年来研究开发的一种热压新技术,它可以提高中密度纤维板和刨花板的生产效率,保证产品质量,减少能耗,降低成本,在中密度纤维板和刨花板生产中具有广阔的应用前景.1蒸汽喷蒸方法简介 运用蒸汽喷蒸技术的热压机具有较特殊的结构,即热压机的压板表面上钻有直径为3mm左右且按一定规律排列的蒸汽喷射孔.为防止细小纤维和刨花堵塞蒸汽喷射孔,压板上垫有防腐蚀、防氧化的金属网垫.网垫的边部用橡皮密封,以防止蒸汽泄漏(见图1). 当压机闭合且板坯被压缩后,通过压板上的蒸汽喷射孔向板坯内喷射具有一定温度和压力的水蒸汽,水蒸汽从板坯表面冲向芯层,对纤维和刨花加 相似文献
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LI Xiazhen XIE Lisheng REN Haiqing XU Ming . Research Institute of Wood Industry Chinese Academy of Forestry Beijing P.R.China . School of Industry Central South University of Forestry Technology Changsha P.R.China 《中国林业科技(英文版)》2007,6(4):31-37
The general steam-injection pressing is mainly used for produce particleboards and medium density fiberboard. However, it is difficult to produce soft fiberboard with desired strength. However, the closing steam-injection pressing that based on the steam-injection pressing could. The wooden frame sealing up the slab could prevent the steam from emitting when the steam injected into the slab. The caloric released by steam condensation make the slab reach high temperature level for a short period. This method is very appropriate for making thick panels in theory, especially for the soft fiberboard. It makes a great leap forward on the hot pressing process that for wood-based panels. Moreover, it will be a meaningful technological breakthrough in developing new products and improving wood utilization. 相似文献
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Kenaf composite panels were developed using kenaf bast fiber-woven sheets as top and bottom surfaces, and kenaf core particles as core material. During board manufacture, no binder was added to the core particles, while methylene diphenyldiisocyanate resin was sprayed to the kenaf bast fiber-woven sheet at 50 g/m2 on a solids basis. The kenaf composite panels were made using a one-step steam-injection pressing method and a two-step pressing method (the particleboard is steam pressed first, followed by overlaying). Apart from the slightly higher thickness swelling (TS) values for the two-step panels when compared with the one-step panels, there was little difference in board properties between the two composite panel types. However, the two-step pressing operation is recommended when making high-density composite panels (>0.45 g/cm3) to avoid delamination. Compared with single-layer binderless particleboard, the bending strengths in dry and wet conditions, and the dimensional stability in the plane direction of composite panels were improved, especially at low densities. The kenaf composite panel recorded an internal bond strength (IB) value that was slightly low because of the decrease of core region density. The kenaf composite panel with a density of 0.45 g/cm3 (one-step) gave the mechanical properties of: dry modulus of rupture (MOR) 14.5 MPa, dry modulus of elasticity (MOE) 2.1 GPa, wet MOR 2.8 MPa, IB 0.27 MPa, TS 13.9%, and linear expansion 0.23%. 相似文献
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Low-density sandwich panels of veneer-overlaid fiberboards of 12 mm thickness for structural use were manufactured at densities of 0.3–0.5g/cm3 using an isocyanate compound resin adhesive and steam injection pressing method. The effects of board density, veneer thickness, and resin content on the fundamental properties of sandwich panels were examined, with the following results: (1) The dry moduli of rupture and elasticity in the parallel direction of sandwich panels with thicker veneers were superior. The dry moduli of rupture and elasticity in the parallel direction of sandwich panels with 2.0 mm thick veneer at densities of 0.4–0.5 g/cm3 were 40–60 MPa, and 5–8 GPa, which were two and four times as much as those of homogeneous fiberboards, respectively. (2) The higher-density panels exhibited tensile failure at the bottom veneer surface during static dry bending in a parallel direction, whereas lower-density panels experienced horizontal shear failure in the core. (3) The dimensional stability of sandwich panels had good dimensional stability, with negligible springback after accelerated weathering conditions. (4) The thermal insulation properties of sandwich panels were found to be much superior to other commercial structural wood composite panels.Part of this report was presented at the 47th annual meeting of the Japan Wood Research Society, Kouchi, April 1997 相似文献
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Xiang-Ming Wang Bernard Riedl Robert L. Geimer Alfred W. Christiansen 《Wood Science and Technology》1996,30(6):423-442
Summary To better understand the curing and bonding behavior of phenol-formaldehyde (PF) resin under dynamic conditions, flakeboards were manufactured either by conventional pressing at 7% or 12% mat moisture content or by steam injection pressing with 10 or 20 seconds steaming duration. Resin-impregnated glass-cloth samples and lap-shear tension specimens were embedded in the core of each flakeboard. After the flakeboards were pressed for various periods of times, the samples and specimens were quickly retrieved. The degree of resin cure was determined on the resin-impregnated glass-cloth samples by dynamic mechanical analysis. The bond strengths were measured from the lap-shear tension specimens on a mechanical testing machine. The results of resin curing and bonding were then correlated to the performance of the resin-bonded boards, which were evaluated by internal bond, modulus of rupture, modulus of elasticity, and thickness swelling. Resin curing and lap-shear bonding did not proceed simultaneously. In conventional pressing, the mat moisture content (MC) at 12% favored resin curing, but slightly retarded lap-shear bonding, as compared to 7%MC. In steam injection pressing, the rates of resin curing and lap-shear bond strength development were much faster for 20 seconds than for 10 seconds of steaming duration. Longer press times were needed to obtain boards with maximum strength in the 12%MC conventional pressing and the 20-s steam duration steam injection pressing than in those conditions where moisture content was lower or steam time was less. The need for longer press times must be attributed to higher internal vapor pressures and/or lower wood and resin component strengths, rather than to incomplete cure or bonding.This material is based on work supported by the Ministry of International Affairs, Quebec Government, the Natural Sciences and Engineering Research Council of Canada, and Laval University (Quebec City). The work was also supported by the U.S. Department of Agriculture under research joint venture agreement FP-92-1835 相似文献
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本文详细论述了美国人造板工业的基本情况、主要产品的开发和研究动向、新工艺和新技术的进展、新型人造板的发展趋势、新胶种的研究和开发、施胶技术的新进展、人工林木材在人造板工业中的开发与利用、人造板的产量和进出口贸易、供需矛盾及解决途径、实现发展目标所采取的措施等。 相似文献
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This study evaluated the potential of steam pre-treatment for making highly compressed phenol-formaldehyde (PF) resin-impregnated
wood at a low pressing pressure. Sawn veneers of Japanese cedar (Cryptomeria japonica) were first subjected to saturated steam at different steaming temperatures (140°-200°C), followed by impregnation with a
20% low molecular weight PF resin aqueous solution resulting in a weight gain of around 50%-55%. Four oven-dried treated veneers
were laminated and compressed up to a pressing pressure of 1 MPa at a pressing temperature of 150°C and pressing speed of
5 mm/min, and the pressure was held for 30 min. Steam treatment, causing partial hydrolysis of hemicellulose, accelerated
the compressibility of Japanese cedar in the PF resin-swollen condition. As a consequence, a discernible increment in density
was achieved at a pressing pressure of 1 MPa due to steam pretreatment between 140° and 200°C for 10 min. It was also found
that even a short steaming time such as 2 min at 160°C is sufficient for obtaining appreciable compression of PF resin-impregnated
wood. The density, Young’s modulus, and bending strength of steam-treated (200°C for 10 min) PF resin-impregnated wood composite
reached 1.09 g/cm3, 20 GPa, and 207MPa, respectively. In contrast, the values of untreated PF resin-impregnated wood composite were 0.87 g/cm3, 13 GPa, and 170MPa, respectively. 相似文献
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Application of cure-accelerated phenol-formaldehyde (PF) adhesives for three-layer medium density fiberboard (MDF) manufacture 总被引:3,自引:0,他引:3
This study was conducted to optimize hot pressing time and adhesive content for the manufacture of three-layer medium density
fiberboard (MDF) through the cure acceleration of phenol-formaldehyde (PF) adhesives by adding three carbonates (propylene
carbonate, sodium carbonate, and potassium carbonate) in the core layer. Carbonate type, carbonate level, PF resin content,
and hot pressing time were evaluated on the basis of the performance of MDF panels prepared. The application of cure-accelerated
PF adhesives by the addition of propylene carbonate reduced both PF resin content and total hot pressing time by 38% and 29%,
respectively, for the manufacture of quality three-layer MDF panels (19.1 mm thickness) under the hot-pressing temperature
of 205 °C. The optimum concentration of propylene carbonate for cure acceleration of PF resin was found to be 3 wt% by weight
based on the resin solids. Bending properties, on one hand, were independent of carbonate type and level, and complied with
the minimum requirements by ANSI. Internal bond (IB) strength, on the other hand, was closely related with carbonate types
and level used.
Received 13 March 1999 相似文献
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To improve the properties of particleboard, boards were produced using a sealed press. With the sealed press, boards were
processed under high-temperature and high-pressure steam. This increased the saturation temperature, causing a dramatic rise
in temperature inside the board, faster curing of the binder, and a shorter pressing time. The boards were bonded with urea
formaldehyde resin, melamine urea formaldehyde resin, or poly(methylene diphenyl diisocyanate) (PMDI). The sealed press improved
the internal bond strength and thickness swelling of boards regardless of the binder used during the reduced pressing time.
The increased bonding strength improved the board properties, allowing PMDI with a lower resin content to be used for bonding
the boards. 相似文献