Preparation of composite board using foil-laminated and plastic-laminated liquid packaging paperboard as raw materials

We investigated the properties of composite board formed using base sheets of aluminum foil-laminated and polyethylene (PE) plastic-laminated liquid packaging paperboard (LP) as an alternative to recycling these items in wastepaper stream. Boards of different specific gravities ranging from 0.55 to 0.75 were made by pressing shredded LP blended with urea resin having resin content of 6%–10% at 180°C. Subsequently, we also prepared mixed particleboard [wood (WD) particles and LP mixed], three-layered particleboard (LP as the middle layer, WD in the upper and lower layers), and wood particleboard all having resin content of 10% and various specific gravities. Static bending and internal bonding strengths and thickness swelling of the specimens were determined to examine their properties. At the same specific gravity, the properties of LP particleboards were affected by their resin content. The modulus of rupture (MOR), modulus of elasticity (MOE), and internal bond strength of the LP particleboards increased with increasing specific gravity of the boards at the same resin content, but thickness swelling of the LP particleboards showed the reverse trend. The average MOR of the LP particleboards approximated that of the mixed particleboards and was greater than those of the three-layered particleboards and wood particleboards. Internal bond strength and thickness swelling of the LP particleboards were smaller than those of the other particleboards. Based on the above observations, we deemed that LP can be made into composite boards with adequate properties either alone or mixed with wood particles.     

Upgrading of urea formaldehyde-bonded reed and wheat straw particleboards using silane coupling agents

Reed and wheat straw particleboards bonded with urea formaldehyde (UF) resin were manufactured from two different material configurations (i.e., fine and coarse particles). The board densities were in the range of 0.550–.90g/cm³. The effects of particle size and board density on the board properties were examined. The properties of particleboard produced from fine particles were better than those made from coarse particles. An increase in board density resulted in a corresponding improvement in the board properties. The properties of OF bonded reed and wheat straw particleboards were relatively lower than those of commercial particleboards. Three silane coupling agents were used to improve the bondability between the reed and wheat particles and OF resin. Results of this study indicate that all the board properties were improved by the addition of silane coupling agent. The degree of improvement achieved from each coupling agent was different; epoxide silane was found to be more effective for reed straw particleboard, and amino silane was better for wheat straw particleboard.     

刨花形态,树皮含量及石膏质量与石膏刨花板性能的关系

对刨花形态、树皮含量及石膏粉质量与石膏刨花板性能之间关系的研究结果表明:保持一定的刨花长度有利于提高石膏刨花板的静曲强度;石膏刨花板的静曲强度随着木刨花中树皮含量的增加而下降,但把树皮作为填料加入石密刨花板能使板子强度得以提高,不同产地的石膏粉制成的石膏刨花板性能差异很大,按建筑石膏粉标准测定的性能指标及相组成与石膏刨花板的性能之间无显著的相关关系。     

Properties of white birch (Betula papyrifera) outer bark particleboards with reinforcement of coarse wood particles in the core layer

? This study proposes substituting traditional raw materials in the surface layers of wood particle-boards with the water resistant white birch (Betula papyrifera) outer bark particles, which can help improve the dimensional stability of manufactured mixed particleboards, thereby alleviating shortages of raw material in a cost-efficient manner.

? Mixed particleboards were fabricated in the laboratory using untreated or alkali treated white birch outer bark particles as substitute material. These particles were resinated successively with three percentages of phenol-formaldehyde resin. Overall, the results of this study clearly demonstrate that the panels could be manufactured using up to 45% of the proposed substitute material and still maintain the required mechanical and physical properties.

? Alkali treatment was used to remove natural wax from bark particles surface which hinders resin adhesion. This treatment negatively affected mechanical and physical properties of finished panels and the variation of phenol-formaldehyde resin percentage in the bark particles significantly affected only their hardness.

? Panel with untreated bark particles in the surface layers, resinated with 5% phenol-formaldehyde resin was selected as the best with the help of a statistical analysis carried out in a factorial complete block design, especially from the dimensional stability criterion.

     

Properties of wheat straw particleboards bonded with different types of resin

Wheat straw particleboard bonded with a urea–formaldehyde (UF) resin, usually employed in the manufacture of wood-based particleboards, or with a resin based on epoxidised oil was manufactured using a compression molding machine. The effects of resin type on internal bond strength, flexural modulus, and thickness swelling were examined. The properties of boards using UF resins were poor. Internal bond strength and thickness swelling, linked to adhesion quality, were especially low. The high compatibility between straw particles and oil-based resin was explained in terms of straw surface free energy. In straw, this parameter exhibits a much lower polar component than wood species and leads to higher compatibility with resins based on oil than with water-soluble systems like UF.     

UF/PDMI组合胶黏剂在刨花板生产中的应用

采用脲醛树脂(UF)/聚合异氰酸酯(PDMI)组合胶黏剂,以不同的组合配比在较低热压温度(160℃)条件下用高含水率(9.0%)杂木刨花制备刨花板,检测其静曲强度、内结合强度以及2h和24h吸水厚度膨胀率。结果表明:聚合异氰酸酯(PDMI)的引入,可以显著提高刨花板的物理力学性能和耐水性能;将刨花终含水率提高至9.0%可节约刨花干燥能耗达13.0%以上;与脲醛树脂胶黏剂(UF)相比,使用PDMI/UF配比为1∶9的(10.0wt%PDMI)组合胶黏剂可以提高刨花板静曲强度80%,提高内结合强度150%;在不添加防水剂的条件下,可以将板材的2h吸水厚度膨胀率由31.0%提高至21.0%。该研究可为刨花板节能环保生产提供新思路。     

Investigation of the effects of bark fiber as core material and its resin content on three-layer MDF performance by response surface methodology

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.     

Effect of furnish type and high-density raw material from mill residues on properties of particleboard panels

The purposes of this study were to examine the use of furniture mill residues containing high-density raw materials in particleboard production and to evaluate the effect of mixing several types of furnish on board performance. Wood wastes collected from the furniture industry in Japan containing matoa (Pometia pinnata), Douglas-fir (Pseudotsuga menziesii), and sugi (Cryptomeria japonica) with different particle shapes were prepared as raw materials for use in the manufacture of experimental particleboards. Seven board types and three mixed boards were manufactured with three replications. Methylene diphenyl diisocyanate (MDI) resin was applied at 6 % content in mat preparation. The pressing conditions were temperature of 180 °C, initial pressure of 3 MPa, and pressing time of 5 min. The target density was 0.72 g/cm³. This study showed that matoa particleboard had properties suitable for use in interior applications, although its properties were considered inferior compared with other particleboards. Improvement of matoa particleboard could be achieved by mixing with higher quality wood particles such as those from sugi or Douglas-fir. The furnish type used in this study affected board performance. All residues from furniture mills have the potential to be used for particleboard production, even when they contain different furnish types and wood species.     

Effect of thermo-mechanical refining on properties of MDF made from black spruce bark

The effects of thermo-mechanical refining conditions on the properties of medium density fiberboard (MDF) made from black spruce (Picea mariana) bark were evaluated. The bark chips were refined in the MDF pilot plant of Forintek Canada Corporation under nine different refining conditions in which preheating retention time was adjusted from 3 to 5 to 7 min and steam pressure was set at either 0.6, 0.9 or 1.2 MPa. The resulting bark fibers were blended with 12% UF resin (based on oven-dry fiber weight) using a mechanical blender. The resinated fibers were manually formed into fiber mats and hot-pressed into MDF panels using consistent parameters. Two panels for each refining condition were produced, resulting in a total of 18 panels. Analysis of variance (ANOVA) was used to analyze the significance of factors. Regression coefficients and 3D contour plots were used to quantify the relationship between panel properties and the two test factors. The results from this study indicated that the preheating retention time was a significant factor for both modulus of rupture (MOR) and modulus of elasticity (MOE), the steam pressure was a significant factor for internal bond strength (IB), MOR and MOE, whereas both factors were insignificant for thickness swelling, water absorption and linear expansion. The properties of MDF panels were quadratic functions of retention time and steam pressure. Compared to the ANSI standard for 120-grade MDF, most panels with a nominal density of 950 kg/m³ had very high IB (>1 MPa) and acceptable MOR, MOE and dimension stabilities. These results suggest that black spruce bark residues can be considered as a potentially suitable raw material for manufacturing MDF products.     

Straw-wood composites bonded with various adhesive systems

In order to study the feasibility of utilizing wheat straw as an alternative raw material for panels, experimental one-layer particleboards were produced by mixing straw with industrial wood particles in various proportions (100:0, 75:25, 50:50, 25:75, 0:100). Three different adhesive systems were used for blending the raw materials: a UF resin (E₂ grade), a PMDI resin and various UF:PMDI combinations (10:0, 8:2, 7:3, 6:4, 5:5). The evaluation of the mechanical and hygroscopic properties of panels showed the following results: Partial replacement of wood particles from straw in panels bonded with pure UF resin resulted in deterioration of all properties except linear swelling. Partial or whole substitution of wood by straw in PMDI bonded panels, improved the bending strength and all hygroscopic properties of the panels but reduced the internal bond (dry and wet) and screw holding strength, although to a much smaller degree compared to UF bonded panels. The properties of panels bonded with various UF:PMDI combinations and comprising 50% wood and 50% straw were considerably improved by increasing the PMDI content. In terms of the properties, pure straw panels or panels made of certain wood/straw mixtures, if bonded with PMDI resin or the appropriate UF:PMDI combination, can be used for specific applications where high quality panels are required according to the specifications of the related standards. Received 11 February 1998     

秸秆刨花板性能分析

对普通木质刨花板、麦秸刨花板及稻草刨花板进行了密度、含水率、吸水厚度膨胀率、静曲强度和弹性模量、内结合强度、表面结合强度及握钉力的测试,结果表明,麦秸刨花板在强度方面不及木质刨花板,稻草刨花板在抗弯性能上也无法满足要求,两种秸秆板的握钉力都较差。产生上述差距的关键原因是板坯的密度,另外,与原料形态、加工工艺、机械设备等也有关系。     

Investigation of a new natural particleboard adhesive composed of tannin and sucrose

In the face of dwindling fossil fuel resources and the environmental imperative to reduce emissions associated with petrochemistry, there is strong demand for a wood composite bonding procedure using natural alternatives. In this study, particleboards were manufactured with a new material adhesive composed of tannin and sucrose, and hot-pressed at 200 °C for 10 min, to a target density of 0.8 g/cm³. We found optimal values for the mat moisture content, the ratio of tannin to sucrose and the resin content of 3–6 wt%, 25/75 and 30–40 wt%, respectively. When the particleboards were manufactured under these optimum conditions, the modulus of rupture and the modulus of elasticity were in the range of 19.6–21.2 MPa and 4.6–5.0 GPa, respectively. The internal bond strength was in the range of 1.1–1.3 MPa. Based on these results, the mechanical properties of particleboard bonded with tannin and sucrose were higher than the requirements of the JIS A 5908 type 18 standard (2003). In the thickness swelling test (TS), the value was in the range of 20–23 %; as the ratio of sucrose and resin content increased, the TS value decreased. The reaction mechanism between tannin and sucrose was studied by fourier transform infrared spectroscopy, and the dimethylene ether bridges were observed. Consequently, it is possible that a tannin and sucrose mixture can be used as a natural adhesive for particleboard.     

The influence of silane coupling agent and poplar particles on the wet-tability,surface roughness,and hardness of UF-bonded wheat straw （Triticum aestivum L.）/poplar wood particleboard

We used silane coupling agents to improve the bonding ability between wheat straw particles and UF resin, and investigated surface properties （wettability and surface roughness） and hardness of parti-cleboard made from UF-bonded wheat straw （Triticum aestivum L.） combined with poplar wood as affected by silane coupling agent content and straw/poplar wood particle ratios. We manufactured one-layered particleboard panels at four different ratios of straw to poplar wood par-ticles （0%, 15%, 30% and 45% wheat straw） and silane coupling agent content at three levels of 0, 5% and 10%. Roughness measurements, average roughness （Ra）, mean peak-to-valley height （Rz）, and root mean square roughness （Rq） were measured on unsanded samples by using a fine stylus tracing technique. We obtained contact angle measurements by using a goniometer connected to a digital camera and computer sys-tem. Boards containing greater amounts of poplar particles had superior hardness compared to control samples and had lower wettability. Panels made with higher amounts of silane had lower Rq values.     

Effect of log position in European Larch (Larix decidua Mill.) tree on the technological properties of particleboard

The impact of log position in European Larch (Larix decidua Mill.) tree on the physical, mechanical, and surface properties of the particleboard was investigated. The logs were divided into five segments from the butt to the top of tree, which were 0–3 m, 3–6 m, 6–9 m, 9–12 m, and 12–15 m, respectively. The fiber length and wall thickness of the wood decreased with the increase in the tree height while the lumen diameter decreased. Similarly, the amount of cellulose and lignin decreased with the increase in tree height while the amount of hemicelluloses increased. The highest solubility values (hot and cold water, NaOH, and alcohol-benzene) and pH of the wood were found in the butt log, followed by the middle log, and top log, respectively. The physical (thickness swelling, water absorption) and mechanical properties (modulus of rupture, modulus of elasticity, and internal bond), and surface quality (surface roughness and contact angle) of the particleboards were negatively affected by increasing tree height. The best properties were obtained for the particleboards produced from the particles of the butt log (0–3 m).     

用红外光谱分析刨花蒸汽处理后成分的变化

用红外光谱法分析了云杉和白桦刨化蒸汽处埋后成分的变化。红外谱图不出了蒸汽处埋后刨花中的半纤维素和羟基比未处理的减少了,这是蒸汽处理改善刨花板尺寸稳定性的主要原因。红外谱图还示出了在同样的蒸汽处理条件下,白桦中半纤维素和羟基的减少程度大于云杉的减少程度,因此蒸汽处理后白桦刨花板尺寸稳定性的改善程度大于云杉刨花板的改善程度。     

Quantification of urea formaldehyde resin in wood fibers using X-ray photoelectron spectroscopy and confocal laser scanning microscopy

The potential merits of X-ray photoelectron spectroscopy (XPS) technique for the quantification of nitrogen on the wood fiber surface before and after resination with UF resin was investigated and the resin content was calculated. The bulk nitrogen content of the fibers obtained by XPS after grinding was compared with those obtained by combustion and Kjeldahl methods. Four different fluorescence staining agents were tested by UV spectroscopy. Their λ_max shifted to longer wavelengths when reacted with UF resin. Appropriate analysis conditions were tested for a satisfactory analysis of wood fibers by the confocal laser scanning microscopy (CLSM). The result obtained by CLSM was compared with that obtained by XPS.     

高压蒸汽处理对刨花表面自由基浓度的影响

本研究探索高压饱和蒸汽处理刨花对刨花表面自由基浓度的影响。研究中对云杉和桦木两种刨花经不同蒸汽压力和不同时间处理后的ESR图谱进行了分析。结果表明:不论是桦木还是云杉刨花,用1.275N/mm~2压力的饱和蒸汽处理5min后,刨花表面自由基浓度均大于未经蒸汽处理的刨花;用蒸汽处理后的刨花制板,在板的各项性能满足国标一等板要求的前提下能减少施胶量2%,而且板材吸水厚度膨胀率也有明显改善。其原因之一就是由于刨花表面自由基浓度的变化。     

Agricultural residues in panel production – Impact of silica particle content and morphology on tool wear

Abstract

Considering ongoing global deforestation and the increased demand for raw materials in all wood-processing sectors it is necessary to seek and employ alternative resources. Agricultural residues are potential sources of alternative lignocellulose-based raw materials. Research on substitute materials for wood panel production mainly focused on physical and mechanical properties of boards while much remains to be learned about machining. Therefore, studies were carried out to analyse the relationship between ash and silica content and their impact on tool wear. Ash and silica contents of agricultural residues were determined following ISO 3340. Particle morphology and elemental composition of selected materials were analysed using scanning electron microscopy and energy-dispersive X-ray analysis. Tool wear tests were carried out using particleboards made from wheat straw, canola straw and spruce. Analyses of various plant materials displayed no correlation between ash and silica content. Bio-mineralised silica structures in wheat and canola were different compared to coarse silica found in wood-based particleboard. Tool wear caused by these agricultural residues was just moderately increased compared to wood, despite the fact that their silica contents were many times higher. Furthermore, the impact of abrasive substances on wear behaviour was influenced by the density of the panels.     

改性胶粘剂对稻壳-木材复合材料性能影响的研究

稻壳的外表面覆盖有二氧化硅膜,使用传统的脲醛树脂(UF)和酚醛树脂胶(PF)生产的100％的稻壳板难以达到木质刨花板的质量指标。本研究采用以异氰酸酯(ISO)改性的脲醛树脂和酚醛树脂胶制造稻壳-木材复合材料。稻壳与木片的混合比例为1:1,施胶量为7％,设计密度0.8g/cm3。试验结果表明,3:4的ISO/UF、2:5的ISO/PF、改性胶粘剂制备的板材的物理力学性能达到国标刨花板二等品的要求;用3:4的ISO/PF改性胶粘剂制备的板材达到优等品的要求。     

LARCH BARK TANNIN ADHESIVE FOR EXTERIOR PARTICLEBOARD

INTR0DUCTI0NChinaisacountrywhichhasnotade-quateforestresources.Itsforestcoverson-lyaboutl3%ofthewh01ecountry.Inor-dertomeetthedevelopmentofnationaleconomy,wemustmakegreateffortstodevelopman-madepanelindustryandmoreefficientlyusetheforestresources.Inthepresent,becauseoftheshortsupplyofchemicalmaterials,thepriceofphenolinthemarketcontinuestogoupwhichledtheincreaseofadhesivemanufacturecost.Findingnewphenolicmateria1sinplaceofphenolisaneffectivemethodtoreducetheadhesivecost.Vegetab1etanninsar…