木质素基豆粕胶黏剂胶合板热压工艺研究

以酶解木质素和豆粕为原料制备了木质素基豆粕胶黏剂,优化了木质素基豆粕胶黏剂应用于杨木胶合板的热压工艺参数,探讨了不同工艺参数对胶合板胶合强度的影响。试验结果表明,木质素基豆粕胶黏剂制备胶合板的优化热压工艺参数为热压温度120℃、热压时间7.5 min(75 s/mm)、热压压力0.9 MPa、单面施胶量180 g/m²;影响胶合板胶合强度的工艺参数主次顺序是热压温度、热压压力、施胶量、热压时间;采用优化热压工艺条件制备3层胶合板,其Ⅱ类胶合强度大于1.0 MPa,符合GB/T 9846-2015《普通胶合板》中Ⅱ类胶合板要求。     

花生蛋白基胶黏剂应用于胶合板热压工艺研究

为了推广花生蛋白基胶黏剂在胶合板中的应用以减少甲醛的释放,优化花生蛋白基胶黏剂应用于杨木胶合板热压条件,分析热压条件对胶合板湿态胶合强度的影响。结果表明:4个因素对湿态胶合强度的影响大小依次为:热压温度热压时间涂胶量热压压力;胶合板的最佳热压条件为热压温度120℃、热压时间8 min、热压压力1. 2 MPa、涂胶量220 g/m~2,在此条件下制备的胶合板湿态胶合强度为1. 09 MPa,符合GB/T 9846—2015中I类胶合板的要求(≥0. 70 MPa),且该热压工艺条件在工业化生产中能够实现。红外光谱分析表明固化后花生蛋白基胶黏剂亲水性基团减少,同时酰胺键增加,说明内部基团发生交联反应。     

三种特种性能胶

D5046型(冷、热压)胶 D5046型(冷、热压)胶适用于热压和冷压二种工艺。该胶用于多层胶合板、多层实木、多层竹木、复合地板等胶合。     

豆渣苯酚液化树脂胶热压桦木胶合板的研究

通过正交试验法,探讨用豆渣苯酚液化树脂胶压制桦木三层胶合板的热压工艺,并对结果进行极差和方差分析,得到最优热压工艺参数:热压温度160 ℃、热压压力1.2 MPa、热压时间5 min、涂胶量240 g/m2.在此工艺参数条件下压制的桦木胶合板,试板的胶合强度可满足GB/T 9846-2004中Ⅰ类胶合板的要求.     

影响薄木饰面家具板件透胶率的因素研究

以红栎、白栎、槭木、黑胡桃等薄木为饰面材料，杨木多层胶合板为基材，研究了添加剂用量、涂胶量、热压压力、热压温度、热压时间等工艺因素对不同树种薄木饰面家具板件透胶率的影响。研究结果表明，红栎贴面板透胶最严重，其次是槭木和黑胡桃，白栎透胶最少。对于红栎，涂胶量是最重要的影响因素；对于槭木，涂胶量和热压压力是最重要的影响因素；对于黑胡桃，热压压力的是最重要的影响因素；对于白栎，热压温度和热压时间是最重要的影响因素。     

豆胶制造速生杨木Ⅱ类胶合板的工艺研究

研究了热压温度、热压压力、热压时间和涂胶量对豆胶制造速生杨木Ⅱ类胶合板性能的影响,得出了较佳工艺参数。     

胶合板发明专利

正申请号:CN201611236014.9发明名称:一种胶合板及其制备方法公开号:CN106827109A申请人:中国林业科学研究院木材工业研究所摘要:一种胶合板及其制备方法。所述胶合板包括多层单板,所述胶合板的表面一层或更多层单板内含有防腐剂和/或阻燃剂。方法包括:将单板表面涂覆胶黏剂,将单板叠加,先预冷压后热压或热压固化胶黏剂,最后通过浸注处理使所述胶合板的表面一层或更多层单板内含     

木塑复合胶合板热压复合因子研究

以杨木单板、低密度聚乙烯制备木塑复合胶合板为研究对象,采用正交试验L9（3^4）系统分析了热压温度、热压时间和塑料加入量等热压复合因子对胶合性能的影响。采用方差与极差方法进行试验分析,结果显示在试验选定的因子水平下,热压温度和热压时间对胶合强度影响不显著,塑料加入量对胶合强度影响非常显著,胶合强度随塑料加入量的增加而增加。筛选出最佳工艺复合因子：热压温度140℃、热压时间3min、塑料加入量0．34Kg／m2,采用此工艺条件制备的胶合板进行性能验证,其胶合强度大大高于胶合板国家标准中Ⅱ类胶合板的性能要求。     

浅谈缩短热压时间的几种途径

建湖县万友人造板有限公司在胶合板生产中,由于热压时间长制约了胶合板产量的提高,笔者通过多次小样试验和批量生产,达到了缩短热压时间,提高胶合质量的目的。１严格控制脲醛树脂的质量胶合板质量的好坏,脲醛树脂胶的质量是关键。我厂自行研制生产了不脱水低克分子比低毒性的ＤＱ－３型脲醛树脂胶,该胶改变传统的生产工艺,由２次投料改进为３次投料,由大碱性投料→酸性投料→碱性投料,促进了二羟甲基脲的大量生成,形成稳定线性结构树脂。该胶有３个鲜明特点：①耐水性能好。在冷水中摇匀能形成“胶钉”抱成一团,粘烧杯不容易被冷…     

胶合板用黑荆树单宁胶粘剂

用PF和PUF树脂代替聚甲醛作交联剂配制单宁胶,系统进行了交联剂用量、pH值及涂胶量、陈放时间、热压温度和时间等胶压工艺条件压板试验.在此基础上压制了60×60cm椴木、马尾松胶合板,证明该单宁胶压制的板符合GB9846.488标准中I类胶合济的质量要求.     

Effects of resin open time and melamine addition on cold pre-pressing performance of a urea–formaldehyde resin

The pre-pressing performance of urea formaldehyde resins has a significant impact on plywood production efficiency. This paper reports on the effects of the time elapsed after the addition of the hardener (“resin open time”) and of a melamine addition on the cold pre-pressing performance of UF resins. The changes in pH and viscosity, the thermal behaviour, and the structural composition as well as the performance during cold pre-pressing of veneers were investigated. Cold pre-pressing performance was measured by testing pre-pressed three-ply plywood stacks. The results showed that the cold pre-pressing performance is enhanced with longer time after preparation of the resin mix before application onto the veneers and also by longer pre-pressing times. All plywood stacks with at least 2 h pre-pressing time reached the so-called G1 grade (where the re-opened area of the cold pre-pressed plywood stack was 0), which meets the industrially accepted requirements for plywood fabrication. Further, the addition of melamine improved the cold pre-pressing behaviour compared to the investigated UF resin without melamine, showing an earlier start of the development of the pre-pressing shear strength and higher G grades at the various cold pressing times. There are two main reasons for the enhanced cold pre-pressing performance of the resin under the investigated conditions: (1) influence of the “resin open time”: a certain further condensation of the resin after preparing the glue mix (addition of hardener) leading to increased molar mass and viscosity ultimately transforming the resin from liquid-state to gel-state; (2) a higher methylol content in the resin after incorporation of melamine into the resin, which enhanced the formation of hydrogen bonds between the resin and the wood surface. These conclusions represent a feasible approach for the improvement of the cold pre-pressing properties and thus the practical applicability of UF resins with low molar ratios.     

Cold tack of urea formaldehyde resins as an important factor in plywood production

The ability of urea formaldehyde (UF) resins to develop cold tack is needed in plywood production during pre-pressing in a cold press to ensure that the veneers stick together, can be transported, and fit into a multi-daylight hot press. The influence of defined factors on the cold tack was analyzed by determining the tensile shear strength of uncured birch veneers bonded with UF resin, and the statistically significant impact factors were determined. The factors tested were lay-up time, resin amount, resin age, moisture content, veneer temperature and pre-press time. Moisture content and veneer temperature had the highest impact on the cold tack of UF resins. A negative impact of high moisture content on the tensile shear strength and therefore on the cold tack of UF resins was proven as well as a positive impact of a comparably high (30 °C) veneer temperature. Lay-up time and pre-press time showed a minor impact on the tensile shear strength. Models were created using Design-Expert software to calculate the optimum operation conditions for cold tack.     

Exterior plywood resins formulated from Pinus pinaster bark extracts

Phenol-tannin-formaldehyde resins prepared by copolymerization of resoles andPinus pinaster bark tannins were used for bonding eucalyptus plywood boards. The dependence of board quality on the formaldehyde/phenol ratio F/P, the overall soda/phenol ratio S/P and the viscosity of the resol was studied using a 2×2×2 factorial design. The most critical of the variables studied was S/P, the best results being obtained with its lower value. A follow-up study using a lower S/P value confirmed this trend, better results being obtained than with commercial phenolic resins. Moreover, the pine-based resins allowed a press temperature of 160°C to be used, which further improved board quality.     

Simultaneous veneers incising and lower pressing temperatures—the effect on the plywood pressing time

It was shown that incising of veneers (60–15 m/m²) prior to plywood bonding allowed reduction of pressing time by 8–9% for a pressing temperature of 90°C when compared to the controls. Nevertheless, with pressing temperatures lower than normal and shortened pressing times the shear strengths of the plywood met the requirements of the respective standards.     

Cure properties and adhesive performances of cure-accelerated phenol-urea-formaldehyde resins

The cure properties of cure-accelerated phenol-urea-formaldehyde (PUF) resins with different catalysts [calcium oxide (CaO), sodium carbonate (Na₂CO₃), zinc oxide (ZnO), and magnesium oxide (MgO)] were investigated by gelation test and differential scanning calorimetry (DSC) analysis. The results indicated that catalysts such as Na₂CO₃, ZnO, and MgO were capable of increasing the curing rate and decreasing the curing temperature of PUF resins, however, the CaO inhibited the cure reaction. The formation of methylene bridges was considered to be the main reaction during curing. For the ZnO- and MgO-accelerated PUF resins, the addition reaction of formaldehyde with free phenolic site may act as subsidiary reaction. The activation energies (E _a ) of cure-accelerated PUF resins other than CaO-acceleration were much lower than the control resin. The effects of catalysts and hot press temperature on adhesive performances of PUF resins were also discussed by plywood test. The PUF resins with Na₂CO₃, ZnO, and MgO had higher wet shear strength than the control resin. Hot press temperature had a strong influence on the wet shear strength as well as the catalysts. Among the catalysts, MgO had more significant improving effect on both the curing process and the wet shear strength of PUF resin.     

Simultaneous veneers incising and lower pressing temperatures—the effect on the plywood pressing time

It was shown that incising of veneers (60–15 m/m²) prior to plywood bonding allowed reduction of pressing time by 8–9% for a pressing temperature of 90°C when compared to the controls. Nevertheless, with pressing temperatures lower than normal and shortened pressing times the shear strengths of the plywood met the requirements of the respective standards.     

Preparation and characterization of wood-plastic plywood bonded with high density polyethylene film

This paper presents a study on the potential use of high density polyethylene (HDPE) film as wood adhesive for formaldehyde-free plywood. The physical–mechanical properties of the plywood, including thickness swelling (TS), water absorption (WA), tensile shear strength, modulus of elasticity and modulus of rupture were evaluated. Results show that HDPE film dosage positively affects the properties when ranging from 61.6 to 246 g/m². The performance of these panels was comparable to those of plywood made with commercial urea–formaldehyde (UF) resins. Comparisons of the dimensional stability between the two plywood demonstrated that 7-day TS and WA values of the panels bonded with UF resins were 5.10 and 23.5 % higher than those bonded with HDPE film, confirming the suitability of HDPE for the use as adhesive in wood-based composites intended for indoor applications subjected to high moisture. DMA tests show that HDPE bonded plywood was significantly inferior in thermal stability at 120 °C and above while it presented almost the same dynamic mechanical properties as UF plywood when the temperature was lower than 100 °C, making it suitable to be used as geothermal floor.     

Effects of wood species and adhesive types on the amount of volatile acetic acid of plywood by using desiccator-method

The effects of wood species and adhesive types on the amount of volatile acetic acid and pH values of plywood panels were investigated using high performance liquid chromatography (HPLC). The plywood panels bonded with PF resin emitted more volatile acetic acid than those bonded with UF resins. According to the pH measurement carried out in the absorption solutions for volatile acetic acid emissions, the pH values of beech plywood panels were found to be higher than those of alder plywood panels.     

Reduction of glue consumption in the plywood production by using previously compressed veneer

Zusammenfassung The production of plywood from previously compressed veneer allows to save up to 25% of glue, to halve the roughness of veneer and plywood and to press the plywood at a 22% lower pressure. However, the thickness of plywood reduces from 8.3 mm for uncompressed veneer to 6.4–8.0 mm for compressed veneer, and the density increases from 793 kg/m³ to 807–1005 kg/m³ accordingly.     

Improved water resistance of UF adhesives for plywood by small pMDI additions

Addition of small amounts of isocyanate (pMDI), between 10% and 15% by weight, to UF resins for plywood considerably improve the UF glue line water resistance. Analysis of the plywood by X-ray microdensitometry indicate that on both sides of the glue lines there is a local density increase which reflects either some adhesive diffusion in the wood layers immediately in contact with the glue line, or some extent of wood densification as a result of the gluing process, or both.