Investigation of a new natural adhesive composed of citric acid and sucrose for particleboard

The development of a natural adhesive composed of materials derived from non-fossil resources is a very important issue. In this study, only citric acid and sucrose were used as adhesive materials for particleboard. A water solution in which citric acid and sucrose were dissolved was used as an adhesive, and the manufacture of particleboard with a target density of 0.8 g/cm³ was attempted under a press condition of 200 °C for 10 min. The optimum mixture ratio of citric acid and sucrose and the optimum resin content was 25–75 and 30 wt%, respectively. The modulus of rupture (MOR) and the modulus of elasticity in bending were 20.6 MPa and 4.6 GPa, respectively. The internal bond strength (IB) was 1.6 MPa, indicating that the adhesive had excellent bond strength. The thickness swelling (TS) after water immersion for 24 h at 20 °C was 11.9 %. The board did not decompose even under more severe accelerated treatments. This meant that the adhesion had good water resistance. The MOR, IB and TS of the board were comparable to or higher than the requirement of the 18 type of JIS A 5908 (2003). Consequently, there is a possibility that a mixture of citric acid and sucrose can be used as a natural adhesive for particleboard.     

Characterization of bagasse binderless particleboard manufactured in high-temperature range

This paper describes the features of binderless particleboard manufactured from sugarcane bagasse, under a high pressing temperature of 200–280 °C. Mechanical properties [i.e., modulus of rupture (MOR) and elasticity (MOE) in dry and wet conditions, internal bonding strength (IB)] and dimensional stability [i.e., thickness swelling (TS)] of the board were evaluated to investigate the effect of high pressing temperature. Recycled chip binderless particleboards were manufactured under the same conditions for comparison, and particleboards bonded with polymeric methylene diphenyl diisocyanate (PMDI) resin were manufactured as reference material. The target density was 0.8 g/cm³ for all of the boards. The results showed that the mechanical properties and dimensional stability of both types of binderless boards were improved by increasing the pressing temperature. Bagasse showed better performance than that of recycled chip as a raw material in all evaluations. Bagasse binderless particleboard manufactured at 260 °C had an MOE value of 3.5 GPa, which was equivalent to the PMDI particleboard, and a lower TS value of 3.7 % than that of PMDI particleboard. The MOR retention ratio under the dry and wet conditions was 87.0 %, while the ratio for the PMDI particleboard was only 54.6 %. The obtained results showed the possibility of manufacturing high-durability binderless particleboard, with good dimensional stability and water resistance, which previously were points of weakness for binderless boards. Manufacturing binderless boards under high temperature was effective even when using particles with poor contact area, and it was possible to express acceptable properties to allow the manufacture of particleboards. Further chemical analysis indicated a contribution of a saccharide in the bagasse to the improvement of the board properties.     

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.     

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.     

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。     

Evaluation of the self-bonding ability of sugi and application of sugi powder as a binder for plywood

Binderless particleboards were manufactured from sugi (Cryptomeria japonica D. Don) heartwood and sapwood by hot-pressing (pressure: 5 MPa; temperatures: 180°, 200°, and 220°C; times: 10, 20, and 30 min), and the board properties [internal bonding (IB), thickness swelling (TS), water absorption (WA)] were investigated to evaluate the self-bonding ability. The IB, TS, and WA of the boards from sugi heartwood were better than those of the boards from sugi sapwood at any hot-pressing condition. Therefore, it was suggested that the self-bonding ability of sugi heartwood was superior to that of sugi sapwood. Then, sugi heartwood and sapwood powder with grain size 10 βm were used as a binder for plywoods. Four kinds of plywood were manufactured from the combination of powder and veneer, both of which were prepared from sugi heartwood and sapwood under the same hot-pressing conditions as the binderless particleboard, and the adhesive shear strength and wood failure of the plywood were investigated. As a result, the plywood composed of sugi heartwood veneer met the second grade of JAS for plywood, when either powder was used as a binder, when they were pressed at 200°C for 20–30 min and 220°C for 10 min.     

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.     

Utilization of sweet sorghum bagasse and citric acid for manufacturing of particleboard II: influences of pressing temperature and time on particleboard properties

Development of environmentally friendly particleboard made from sweet sorghum bagasse and citric acid has recently attracted attention. In this study, we investigated the effects of pressing temperature and time on physical properties, such as dry bending (DB), internal bond strength (IB), and thickness swelling (TS) of particleboard. Wet bending (WB), screw-holding power (SH), biological durability, and formaldehyde emission of particleboard manufactured under effective pressing temperature and time were also evaluated. Particleboards bonded with phenol formaldehyde (PF) resin and polymeric 4,4′-methylenediphenyl isocyanate (pMDI) were manufactured as references. Effective pressing temperature and time were 200?°C and 10 min, respectively. It was clarified that DB, IB, and TS satisfied the type 18 requirements of the JIS A 5908 (2003), and were comparable to those of particleboard bonded with PF and pMDI. The WB and SH of particleboard did not satisfy type 18 of JIS. Particleboard manufactured under effective pressing conditions had good biological durability and low formaldehyde emission. Based on the results of infrared spectra measurement, the degree of ester linkages increased with increased pressing temperature and time.     

烟秆制备刨花板的力学性能研究

烟秆为烟草采摘烟口t-后的废弃物,为了更好的利用这种原料,利用不同含水率（9％、6％、3％、0％）和烟秆不同部位（上部、中部和下部）的刨花制成刨花板,测定刨花板的内结合强度、弹性模量和静曲强度,分析含水率和烟秆部位对刨花板力学性能的影响。结果表明,随着含水率从0增加至9％,刨花板的内结合强度从0．35MPa增加至0．58MPa,其弹性模量和静曲强度呈先增后减趋势,当含水率在6％时,烟秆刨花板的弹性模量和静曲强度最大。不同部位的烟秆刨花对刨花板的内结合强度、弹性模量、静曲强度有显著影响,其中,利用中部烟秆刨花制备的刨花板的内结合强度、弹性模量、静曲强度最小。利用烟秆刨花制备的刨花板其力学性能能达到国家标准的要求,因此利用烟秆制备刨花板是可行的。     

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.     

Manufacture of Light-weight Composite Panel from Kenaf

Light-weight composite panels were manufactured using kenaf core particles as core material and kenaf bast fiber-woven sheets as top and bottom surfaces. Methylene diphenyldiisocyanate （MDI） resin was used as the adhesive with the resin content of 4% for core particles and 50 g/m^2 for bast fiberwoven sheets. The target board densities were set at 0.35.0.45 and 0.55 g/cm^3. The composite panels were evaluated With Japanese Industrial Standard for Particleboards （JIS A 5908- 2003）.The results show that the composite panel has high modulus of rupture and internal bonding strength. The properties of 0.45 g/cm^3 density composite panel are： MOR 20.4 MPa. MOE 1.94 MPa, IB 0.36 MPa, WA142%, TS 21%. Kenaf is a good raw material for making light-weight composite panels.     

The effect of urea pretreatment on the formaldehyde emission and properties of straw particleboard

For manufacturing low-formaldehyde emission particleboard from wheat straw and urea-formaldehyde (UF) resins using urea treatment for indoor environments, we investigated the influence of urea treatment on the formaldehyde emission, physical and mechanical properties of the manufactured particleboard. Wheat straws were treated at three levels of urea concentration (5%, 10%, 15%) and 95℃as holding temperature. Wheat straw particleboards were manufactured using hotpress at 180℃and 3 MPa with two types of UF adhesive (UF-45,UF-91). Then the formaldehyde emission values, physical properties and mechanical properties were considered. The results show that the formaldehyde emission value was decreased by increasing urea concentration. Furthermore, the results indicate that the specimens under urea treatment have better mechanical and physical properties compared with control specimens. Also specimens under urea treatment at 10% concentration and UF-91 type adhesive have the most optimum physical and mechanical strength.     

LARCH BARK TANNIN ADHESIVE FOR EXTERIOR PARTICLEBOARD

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

Particleboard made from hammer milled black spruce bark residues

Summary  The disposal of bark residues is an important problem for the forest industry. An important proportion of the bark produced by the paper and lumber industries is used for energy production, but a significant amount of bark is still unused. The objective of this study was to determine the technical feasibility of making particleboards from black spruce bark residues bonded with urea formaldehyde resin and meeting the indoor performance requirements for wood particleboards. In the positive case, this would define a new use for black spruce bark residues. Fresh black spruce bark residues were obtained from a sawmill located in the northeast part of the province of Quebec, Canada. The bark was kiln-dried at 60 °C, the particles were generated from a hammermill and sieved. Particles from 0.02 to 2.0 mm were used in the surface layers and particles from 2.0 to 6.0 mm were used in the core layer. Particleboards of 540 × 560 × 16 mm were made with a laboratory hot press following a factorial design with two manufacturing variables at three levels: (1) wood particles content of the surface layers (0, 25, 50 percent); and (2) UF resin content of the surface layers (12, 14 and 16 percent) with a UF resin content in the core of 8 percent. This resulted in a factorial design of 9 different combinations repeated 3 times for a total of 27 boards. It was observed that the heating kinetics varied according to the wood particles content in the surface layers. The compression ratio of the mat and the board internal bond, modulus of elasticity, modulus of rupture, linear expansion and thickness swell were determined. The results show that it is technically possible to make particleboard from bark residues meeting the American National Standard Institute indoor requirement for wood particleboard under certain conditions. The modulus of rupture of the boards was the most critical property in this study. The best mechanical properties were obtained with a 50 percent wood content and 14 percent resin content in the surface layers. The particleboards produced in this study did not meet the minimal requirements for linear expansion. The temperature measurements performed in the core of the mat during hot pressing show that heat transfer improves with an increase in wood particles content in the surface layers. Received 15 June 1998     

制板工艺因子对硅酸钠/酚醛树脂玉米秸秆刨花板性能的影响

采用硅酸钠/酚醛树脂胶制备玉米秸秆刨花板,考察工艺因子对试板物理力学性能的影响。结果表明:随着施胶量增加、热压温度升高、热压时间延长,试板吸水厚度率逐渐减小,静曲强度、弹性模量和内结合强度呈先增大后减小的趋势。按照优化工艺:施胶量17%、热压温度180℃,热压时间20s/mm,制备试板的吸水厚度膨胀率和力学性能均满足GB/T4897-2015《刨花板》中干燥状态下使用的家具型刨花板的(P2型)的要求。     

Blowout conditions and properties of isocyanate resin bonded particleboard manufactured from high-moisture particles using an air-injection press

Blowouts of particleboards were artificially induced by increasing the vapor pressure inside the boards. Isocyanate resin bonded boards were manufactured from high-moisture particles, and the blowouts and board properties were analyzed. Boards with a high resin content of 5 % showed high bonding strength and did not blow out when pressed at 190 °C, but blew out at a raised temperature of 210 °C to increase vapor pressure inside the boards, thereby showing that blowout occurred when vapor pressure inside the boards exceeded the bonding strength of isocyanate resin. Boards with a low resin content of 2.5 % had low bonding strength and blew out when manufactured without air injection, but were successfully manufactured with air injection that prevents blowouts. However, the injection of high-pressure air reduced the strength properties of the board and increased the coefficient of variation, likely due to the discharge of isocyanate resin from the boards. Therefore, very small local blowouts occurred inside the boards, which lowered the strength properties of some specimens and led to a large coefficient of variation. When the pressure of injected air was lowered, the strength properties increased and the coefficient of variation decreased. This was possibly because the low-pressure air allowed isocyanate resin to remain in the boards, resulting in virtually no parts showing very low-strength properties.     

烟秆/木材刨花板的初步研究烟秆

初步探讨了实验室条件下烟秆/木材刨花板的生产工艺,研究了热压时间、施胶量、密度、木刨花加入量等因素对板材的静曲强度、内结合强度、吸水厚度膨胀率的影响.实验结果表明,烟秆/木材刨花板的静曲强度和吸水厚度膨胀率较纯烟秆刨花板有所提高,内结合强度相差不大.     

复合工艺对竹/塑复合刨花板性能的影响

利用聚乙烯(PE)粉末取代部分脲醛树脂(UF)胶黏剂,与竹刨花制备三层结构竹/塑复合刨花板。通过正交试验探讨PE添加量、UF施胶量、热压温度及热压时间对竹/塑复合刨花板主要物理力学性能的影响。结果表明:较优工艺组合为PE添加量6%、UF施胶量2%、热压温度205℃、热压时间12s/mm,竹/塑复合刨花板达到LY/T1842—2009《竹材刨花板》A类理化性能指标要求;2h吸水厚度膨胀率和甲醛释放量分别为2.6%和2.4mg/100g,与普通竹材刨花板对比,分别减少了54.4%和54.7%;静曲强度达到19.6MPa,提高了14.0%。采用PE粉末替代部分UF胶黏剂生产竹/塑复合刨花板可行,且具有广泛的应用前景。     

制造工艺因素对刨花板吸水厚度膨胀率的影响

结合众多实验结果，讨论了刨花板制造工艺中12个主要因素－热压温度、热压时间、热压压力、板的密度、刨花含水率、施胶量、施蜡量、胶剂种类、刨花形态、刨花原料种类、刨花预处理、成板的二次压制处理对刨花板吸水厚度膨胀率的影响。结果表明，降低刨花板的24h吸水厚度膨胀率要通过降低其不可逆厚度膨胀率获得，而降低不可逆厚度膨胀率的实质是尽量以非膨胀功耗能释放内应力，减少粘弹性变形和胶接点破坏。研究还表明，上述12个制板要素中，除施蜡量外，都对不可逆厚度膨胀率有很大的影响，因此选择合理的制板工艺因素对刨花板的尺寸稳定性很重要。     

异氰酸酯树脂胶粘剂刨花板制板工艺研究

研究了用异氰酸酯树脂胶粘剂制造刨花板的工艺条件,详细讨论了热压温度、热压时间、密度含水率、施胶量和施蜡量和对刨花板为物理力学性能的影响。结果表明：刨花含水率是继热压工艺三个因素之后的重要影响因子。研究中还发现了“厚度膨胀率平行性”现象,对其进行的深入分析研究揭示了不可逆厚度膨胀率为２４ｈ吸水厚度膨胀率的关系,总结出板材２４ｈ吸水厚度膨胀率的改善只能通过改善不可逆度膨胀率获得。研究结果还表明,利用Ｙ