出口胶合板甲醛释放量变化分析

应用GB／T17657——1999《人造板及饰面人造板理化性能试验方法》中的干燥器法,对胶合板样品甲醛释放量进行测定,分析总结了出口胶合板甲醛释放量变化规律。     

出口胶合板甲醛释放量变化分析

应用GB/T 17657—1999《人造板及饰面人造板理化性能试验方法》中的干燥器法,对胶合板样品甲醛释放量进行测定,分析总结了出口胶合板甲醛释放量变化规律。     

Zur Bedeutung von schnellwüchsigen Baumarten als Rohmaterial für die Holzwerkstoffherstellung unter besonderer Berücksichtigung von Pappelholz für Spanplatten

In the Federal Republic of Germany increasing attention is paid to the possibilities of using midi- and minirotation poplar wood as raw material for wood-based panels. In the article a brief account is given on the state of knowledge regarding the behaviour of poplar wood in particleboard manufacture. Debarked poplar chips are easily bondable with conventionel organic and inorganic binders. The use of a high amount of bark is deleterious to the physical-mechanical properties of boards, however, bark decreases the formaldehyde release of wood-based panels significantly. Due to its low density, poplar wood can be used for the production of high strength particleboards at low density level. The paper shows that no comprehensive data is available on the behaviour of tension wood towards bonding. Moreover, no detailed information is accessible on the gluability of juvenile wood. In the paper experimental results are reported concerning the properties of particleboards from 5-year old balsam poplar trees using UF- and PF-resins as binders. The results indicate clearly that there are no significant differences in the bonding strength between different clones. Using UF-resins boards with acceptable quality can be made from chips containing about 25% bark. The PF-bonded boards showed acceptable dry bonding strength. However, the wet strength was fast above or fast below the value required by the standard.     

Indoor wood dust analysis during machining with an original experimental device

Particles generated by wood machining have a proven impact on the health of users and woodworkers. The aim of this study was to quantify and describe wood particles in solid and gas phases to reliably and reproducibly characterise these emissions. First, we developed an experimental device that produced particles from solid wood and wood-based panels using portable machine tools. The objective was to study the particles emitted by wood machining while avoiding ambient pollution. Based on own technical specifications, the experimental system was defined and composed of various elements that integrated treatment of inlet air through wood machining to the analysis section that allows solid and gas phases. The first experiments were carried out in sanding and sawing modes on materials used in construction, including solid wood (spruce) and composite panels (particle board (PB), oriented strand board (OSB), and medium density fibreboard (MDF)). Wood-based panels showed more emissive behaviour than solid wood, both for the solid phase and the gas phase. These tests validate the feasibility of generating and measuring particles and emissions of volatile organic compounds (VOCs). Further modifications to the experimental device would enable us to integrate additional devices, such as toxicological ones, to better understand the impact of these wood particles on the health of woodworkers.

     

木材工业用胶黏剂低毒化研究进展

从合成树脂型胶黏剂的改进和生物质胶黏剂开发利用两方面,总结了木材工业用胶黏剂的低毒化研究进展,并提出根据我国国情着力发展生物质胶黏剂的建议。     

实验检测人造板甲醛释放量的几点建议

人造板甲醛释放量是人造板检测的重要指标之一,也是人造板市场和国家监管的主要指标。本文就人造板检测中穿孔萃取法检测甲醛释放量的细节性事项提出一些建议。     

实验检测人造板甲醛释放量的几点建议

人造板甲醛释放量是人造板检测的重要指标之一,也是人造板市场和国家监管的主要指标。本文就人造板检测中穿孔萃取法检测甲醛释放量的细节性事项提出一些建议。     

浅议低游离甲醛人造板中游离甲醛的测定

探讨低游离甲醛人造板的游离甲醛测定方法，对如何有效降低测定误差及提高其精确度的各种影响因素进行分析。     

On the formaldehyde release of wood particles

The emission of formaldehyde from softwood particles, as measured by the flask method (EN 717-3), depends highly on the particle size. Therefore, no definite value for the formaldehyde release from wood can be given.     

Heat-treatment with the vacuum-press dewatering method: chemical properties of the manufactured wood and the condensation water

Certain properties of wood can be improved with thermal modification, allowing its application fields to be considerably extended without the use of any chemical additives. This study focuses on the chemical investigation of hardwood (oak, beech, ash) products heat-treated with an industrial scale vacuum-press dewatering method (Vacu³) as well as on the evaluation of the parameters of the condensation water exhausted during the treatment. Wood modification was carried out at 195 and 210 °C. The pH value, loss of VOCs and total phenols were determined from the samples. Waste waters collected after the treatment cycles were investigated for pH, conductivity, COD, VOCs, total phenols and also for possible utilizable compounds. Release of VOCs from wood can be a health concern. Results show that the losses of the measured components were quite low. The composition of the highly acidic waste waters also depends on wood species, containing mostly phenolic compounds, aldehydes and acids. Possible ways for the utilization of these components need to be worked out in the future.     

The influence of curing conditions on properties of melamine modified wood

The curing conditions influence the material properties of wood modified with methylated melamine formaldehyde resin. To identify the most influential parameters, the process conditions were varied separately. The degree of conversion (differential scanning calorimetry; DSC), work in bending, nitrogen fixation, formaldehyde emission, formaldehyde content and content of free formaldehyde were measured to verify the influence of the curing conditions on the material properties. The temperature and duration positively influenced the curing of melamine resin as the DSC results and the nitrogen fixation indicate. However, the relative humidity (RH) had the greatest influence on the material properties: the formaldehyde properties and the work in bending differed most between dry and high RH processes with the latter producing material being less brittle and having lower formaldehyde emissions. It can be derived that DSC measurements, formaldehyde emission and -content are valuable methods to characterize the influence of curing conditions on the material properties. The formaldehyde content in combination with the emission revealed a different formaldehyde release factor for dry and high RH processes. In the future, the curing process conditions can be designed depending on the desired material properties: dry, high temperature processes will lead to more complete curing, whereas hot steam processes can be used for material with low formaldehyde emissions.     

Improving the environmental profile of wood panels via co-production of ethanol and acetic acid

The oriented strand board (OSB) biorefinery is an emerging technology that could improve the building, transportation, and chemical sectors' environmental profiles. By adding a hot water extraction stage to conventional OSB panel manufacturing, hemicellulose polysaccharides can be extracted from wood strands and converted to renewably sourced ethanol and acetic acid. Replacing fossil-based gasoline and acetic acid has the potential to reduce greenhouse gas (GHG) emissions, among other possible impacts. At the same time, hemicellulose extraction could improve the environmental profile of OSB panels by reducing the level of volatile organic compounds (VOCs) emitted during manufacturing. In this study, the life cycle significance of such GHG, VOC, and other emission reductions was investigated. A process model was developed based on a mix of laboratory and industrial-level mass and energy flow data. Using these data a life cycle assessment (LCA) model was built. Sensitive process parameters were identified and used to develop a target production scenario for the OSB biorefinery. The findings suggest that the OSB biorefinery's deployment could substantially improve human and ecosystem health via reduction of select VOCs compared to conventionally produced OSB, gasoline, and acetic acid. Technological advancements are needed, however, to achieve desirable GHG reductions.     

无甲醛人造板研究现状及应用前景

文章介绍了无甲醛人造板研究的现状、产业化进展及其应用前景,主要包括无甲醛人造板的定义、种类,无甲醛人造板的主要生产工艺过程,无甲醛人造板的性能及应用等.简要评价了无甲醛人造板研究对我国木材工业发展的影响.     

Effects of log storage conditions and steaming process on the formaldehyde emissions of particleboard manufactured from eucalyptus (E. camaldulensis) wood

The aim of this study was to determine the changes in formaldehyde emissions of eucalyptus particleboards produced from logs stored under different conditions (indoor, outdoor, and under water) or steamed. The pH and Stiasny values of particles changed significantly according to the storage condition and log steaming process. The pH values of particles obtained from steamed logs and stored outdoors for 4 months were found to be lower than those of the particles obtained from logs stored in the other aforementioned two conditions. The peaks of acetyl groups in the IR-spectra of the four group particles were similar. There was a strong relationship among the formaldehyde emission values of the panels pressed at 150 °C and the Stiasny values of the particles from which the panels were produced. The formaldehyde emission values of the panels pressed at 190 °C were lower than those of the panels pressed at 150 °C.     

基于干燥器法测定人造板甲醛释放量的方法验证

基于干燥器法测定人造板甲醛释放量的检测方法,系统探究其检出限、测定下限、精密度、准确度等性能参数。     

Effects of log storage conditions and steaming process on the formaldehyde emissions of particleboard manufactured from eucalyptus (E. camaldulensis) wood

The aim of this study was to determine the changes in formaldehyde emissions of eucalyptus particleboards produced from logs stored under different conditions (indoor, outdoor, and under water) or steamed. The pH and Stiasny values of particles changed significantly according to the storage condition and log steaming process. The pH values of particles obtained from steamed logs and stored outdoors for 4 months were found to be lower than those of the particles obtained from logs stored in the other aforementioned two conditions. The peaks of acetyl groups in the IR-spectra of the four group particles were similar. There was a strong relationship among the formaldehyde emission values of the panels pressed at 150 °C and the Stiasny values of the particles from which the panels were produced. The formaldehyde emission values of the panels pressed at 190 °C were lower than those of the panels pressed at 150 °C.     

Lignin-based wood panel adhesives without formaldehyde

Lignin-based wood adhesives prepared without formaldehyde substituted by non-volatile non-toxic aldehyde, namely glyoxal, were prepared and tested for application to wood panels such as particleboard. The adhesives yielded good IB strength results of the panels, enough to comfortably pass relevant international standard specifications for exterior-grade panels. The adhesives also showed sufficient reactivity to yield panels in press times comparable to those of formaldehyde-based commercial adhesives.     

利用木质废弃物生产人造板的研究现状及存在的问题

介绍了木质废弃物生产人造板的意义和研究现状,简单论述了其存在的问题和发展前景.     

On the influence of binder content in particleboards bonded with resins of high and low molar ratio on the formaldehyde release measured by the perforator method

A comprehensive literature survey and the results of investigations clearly show that the influence of resin level in particleboards on the perforator value (EN 120) depends on the molar ratio of the resin used as a binder. In case of high molar ratio resins (F:U 1.6:1) increasing the binder content in the boards leads to an increase in the perforator value of the boards. In contrast, boards bonded with very low molar ratio aminoplastic resins with molar ratio F:U of 1:1 (F:NH₂ 0.5:1) or even lower do not show any noticeable increase in the perforator value on raising the binder level. On the contrary, the measured perforator values may sometimes decline due to increase in the resin content in the boards. The perforator test seems to include two main processes taking place alongside each other: the physical extraction of free formaldehyde and the chemical hydrolysis process of the resin itself, induced by the moisture content of the boards. In case of low molar ratio resins, particularly at very low molar ratios (F:U 1:1 or even lower), free urea may also be present in the resin or added to the resin as a scavenger. Urea seems to react with extracted formaldehyde at high temperature during the extraction process. This lowers the perforator value without necessarily decreasing the emission at ambient conditions. Insofar, inextricably intertwined chemical processes seem to unfold during the extraction process. Additionally, the results show that subtle differences in the perforator value in the very low formaldehyde emission region may remain without noticeable impact on the emission measured by the chamber method (EN 717-1).     

Utilization of bark flours as additive in plywood manufacturing

Increasing demand for wood based panel products and shortage of wood as raw material have triggered many efforts to utilize residues generated annually by the forest industries including a large portion of bark in panel production. In this study, the effects of using bark flours as additives obtained from different wood species (walnut, chestnut, fir and spruce), having much polyphenol content, on some physical and mechanical properties and formaldehyde emission of plywood panels were examined. Wheat flour, which has been used widely as additive in plywood manufacturing, served as control. Plane tree (Platanus orientalis) logs were obtained for veneer manufacturing. Urea formaldehyde (UF) resin with 55 % solids content was used as adhesive. The bonding shear strength, bending strength, modulus of elasticity (MOE), density, equilibrium moisture content and formaldehyde emission of plywood panels were determined according to related standards. It was found that the use of flours obtained from the barks of chestnut and fir trees in the glue mixture decreased the formaldehyde emission of panels. The bonding strength values of the test panels made using the glue mixture including the flour of walnut and spruce barks as additive were lower than those of the panels with adhesive containing the flour of fir and chestnut barks. The panels manufactured with adhesives including the flour of fir bark gave the highest bending strength and modulus of elasticity values.