共查询到19条相似文献,搜索用时 93 毫秒
1.
2.
我国木材胶粘剂发展概况 总被引:2,自引:0,他引:2
综述中国木材胶粘剂概况.报告了脲醛树脂、酚醛树脂、三聚氰胺-甲醛树脂、单宁胶、本素胶、木材的本体聚合等胶粘剂与粘合技术的改进,并提出有关建议。 相似文献
3.
4.
酚醛树脂胶粘剂的研究进展 总被引:1,自引:2,他引:1
主要介绍了酚醛树脂胶粘剂的研究现状与进展方向,综述了酚醛树脂和酚醛树脂胶粘剂的改性方法。性能的改善提高了酚醛树脂胶粘剂的应用价值,扩大了其使用范围。 相似文献
5.
6.
7.
8.
生物油-酚醛树脂改性淀粉胶粘剂的研究 总被引:1,自引:1,他引:0
为了提高淀粉胶粘剂的耐水性和降低其生产成本,以生物油-PF(酚醛树脂)作为淀粉胶粘剂的改性剂,采用单因素分析法探讨了氧化剂种类、聚合反应温度及固化剂用量等因素对改性淀粉胶粘剂主要性能的影响。结果表明:制备改性淀粉胶粘剂的较佳工艺条件是以高锰酸钾和硫酸为氧化剂,聚合反应温度为75℃,w(固化剂)=12%(相对于胶粘剂总质量而言);在较佳工艺条件下制成的改性淀粉胶粘剂具有良好的胶接性能,并且克服了传统淀粉胶粘剂遇水易开胶、传统PF胶粘剂中游离醛释放量较高等缺点,可广泛用于Ⅱ类胶合板的生产。 相似文献
9.
10.
11.
制备了不同尿素用量的系列尿素改性酚醛(PUF)树脂体系(当尿素用量为苯酚质量的0、25%、43%、66%时分别记为PF、PUF-1、PUF-2、PUF-3),并将其用于制备胶合板,研究树脂在胶合板加工过程中的变化。结果表明:PUF-3树脂与桉木和杨木的接触角为79.6°和81.1°,小于PF树脂的,PUF对桉木相容性比杨木优良,PF树脂则相反;对4种树脂进行DSC分析显示,PF、PUF-1、PUF-2、PUF-3固化速率最大温度分别为146.8、171.4、171.8和171.8℃;PUF-3和面粉共混体系的流变行为显示该共混体系110℃开始发生固化反应,(130±5)℃为较合适的热压温度;对热压前后PF和PUF-3进行热重分析,结果发现PUF的耐高温性能优于PF,热压后形成的结构耐热性也更好;4种树脂压制的胶合板性能达到E0级,甲醛释放量均小于0.5mg/L,胶合强度分别为1.42、1.11、0.98和0.92MPa。 相似文献
12.
The reaction of polycondensation of phenol-formaldehyde (PF) resins in the presence of wood was confirmed to have a lower energy of activation than of the PF resin alone. Under the low temperature and short curing times characteristic of the application of PF resins as thermosetting wood adhesives DSC, TGA, chemical kinetics, and IR of PF resins and relevant model compounds were carried out. These indicated that two effects appear to be present when a PF resin cures on a wood surface, both induced by the polymeric constituents of the substrate, namely carbohydrates and lignin. These appear to be (1) the catalytic activation of the resin self-condensation induced particularly by carbohydrates such as crystalline and amorphous cellulose and hemicelluloses and (2) the formation of resin/substrate covalent bonding, particularly in the case of lignin. The first appears to be, by far, the major cause of the lowering of the activation energy of PF resins curing. The contribution of the second has been found to be very small and often negligble under the conditions pertaining to thermosetting wood adhesives applications. Molecular mechanics results appear to indicate that the marked catalytic activation of PF resins autocondensation and curing appears to be induced by the strong set of PF adhesive/substrate secondary forces interactions which appear to weaken bonds which, by cleavage, lead to PF resins autocondensation. © 1994 John Wiley & Sons, Inc. 相似文献
13.
Liquefaction of southern pine wood in phenol in 30–40 : 70–60 weight ratios resulted in homogeneous liquefied materials, which were directly used to synthesize phenol–formaldehyde (PF)‐type resins. The synthesized resins showed good physical and handling properties: low viscosity, stability for storage and transportation, and resin applicable by a common sprayer. Particleboard panels bonded with the synthesized resins showed promising physical properties and significantly lower formaldehyde emission values than those bonded with the urea–formaldehyde resin control. One deficiency observed for the synthesized resins was lower internal bond values, which might be overcome the use of a hot‐stacking procedure. Overall, the process of wood liquefaction with limited amounts of phenol as a solvent was shown to have the potential of providing practical, low‐cost PF‐type resins with very low formaldehyde emission potentials. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
14.
加快绿色化 迎接新世纪 总被引:1,自引:0,他引:1
在知识经济走向我们的时代 ,木材胶粘剂加快绿色化 ,成为生态材料 ,进入高技术产业行列。在我国 ,下世纪前十年内 ,低毒脲醛胶将成为主流产品 ;现用树脂胶的改性技术日益成熟 ,如三聚氰胺改性脲醛 (MUF)、苯酚改性脲醛 (PUF)等 ;利用天然资源制造的可降解胶粘剂用量提高 ,如木素胶、单宁胶、豆蛋白胶等 ;新产品用胶不断出现 ,如水性异氰酸酯等。另外 ,集科研、开发、生产于一体的专业胶粘剂产业将较快增长。 相似文献
15.
Kenji Umemura Shuichi Kawai Hikaru Sasaki Ryozo Hamada Yasusi Mizuno 《The Journal of Adhesion》1996,59(1):87-100
Steam-injection pressing is a recent development for manufacturing wood products. The curing mechanism and behavior of wood adhesives during steam-injection heating and hot-platen heating may cause differences in both chemical and physical aspects. The curing of wood adhesives under high steam pressure using an especially designed reaction cell is discussed. The adhesives used in this study were phenol-formaldehyde (PF), urea-formaldehyde (UF), melamine-formaldehyde (MF), and isocyanate (IC) resins. At different curing times, the heating temperature (steam pressure) applied to cure the adhesives was 160°C (6 kgf/cm2). Results were examined by analytical methods using FR-IR, 13C-NMR, dynamic mechanical analysis and solvent extraction. (1) By steam-injection heating, PF resin immediately cured to some degree in a few minutes and maintained an equilibrium situation. In this case, the reaction was accompanied by the disappearance of the ether structure. (2) In UF resin, results from IR data clarified different reactions between hot-platen heating and steam-injection heating. During steam-injection heating, as heating time increased, UF resin returned to its liquid state under the influence of hydrolysis. (3) MF resin was almost cured under steam-injection in a short heating time compared with hot-platen heating. (4) IC resin foamed and cured in a short heating time under steam-injection. It was proved that steam-injection heating was more effective than by hot-platen heating for IC resin. 相似文献
16.
The wood powder of Cryptomeria japonica (Japanese cedar) was liquefied in phenol, with H2SO4 and HCl as a catalyst. The liquefied wood was used to prepare the liquefied wood‐based novolak phenol formaldehyde (PF) resins by reacting with formalin. Furthermore, novolak PF resins were mixed with wood flour, hexamethylenetetramine, zinc stearate as filler, curing agent, and lubricating agent, respectively, and hot‐pressed under 180 or 200°C for 5 or 10 min to manufacture moldings. The results showed that physicomechanical properties of moldings were influenced by the hot‐pressing condition. The molding made with hot‐pressing temperature of 200°C for 10 min had a higher curing degree, dimensional stability, and internal bonding strength. The thermal analysis indicated that using a hot‐pressing temperature of 180°C was not sufficient for the liquefied wood‐based novolak PF resins to completely cure. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009 相似文献
17.
利用酚醛树脂与氯丙烯反应,合成出了烯丙基酚醛树脂(APF),并对其固化过程进行了研究。结果表明,烯丙基酚醛树脂不仅能溶于极性溶剂,还能溶于非极性溶剂,其起始固化温度为180℃,比普通的酚醛树脂高。烯丙基酚醛树脂的固化窗口为44℃,其固化是通过双键的加成反应来实现的,固化后树脂为连续相结构。 相似文献
18.
落叶松树皮生物油改性酚醛树脂胶粘剂固化动力学研究 总被引:5,自引:0,他引:5
采用差热分析(DTA)技术测定了普通酚醛树脂(PF)和生物油改性PF在固化反应过程中的热行为,综合运用Kissinger方程、Ozawa方程和Crane方程计算出两者的固化反应动力学参数。研究结果表明,普通PF和生物油改性PF的反应级数分别为0.95和0.93,平均活化能分别为118.24kJ/mol和83.62kJ/mol,指前因子分别为8.302×1010s-1和6.235×103s-1;两者的反应级数较为接近,均可归结为复杂反应,说明生物油改性PF和普通PF的固化反应模式基本相同;与普通PF相比,生物油改性PF具有相对较低的平均活化能(即固化能耗相对较低)。 相似文献
19.
Marzieh Gangi Taghi Tabarsa Sima Sepahvand 《Journal of Adhesion Science and Technology》2013,27(13):1407-1417
The aim of this work is to evaluate performances of tannin-based resins designed as adhesive in the plywood production. For this purpose, a part of phenol formaldehyde (PF) and melamine formaldehyde (MF) in the classic adhesive formulation was replaced by tannin. The physical properties of the formulated resins (rheological characterization, etc.) were measured. In order to analyze the mechanical performance of tannin-based resins, plywood panels were produced and the mechanical properties including tensile strength wood failure and three-point bending strength were investigated. The performance of these panels is comparable to those of plywood panels made by commercial PF and MF. The results showed that the plywood panels bonded with tannin–PF (PFT) and tannin–MF (MFT) resins exhibited better mechanical properties in comparison to the plywood panels made of commercials PF and MF. The introduction of small properties of tannin in PF and MF resins contribute to the improvement of the water performance of these adhesives. The formaldehyde emission levels obtained from panels bonded with tannin-based resins were lower than those obtained from panels bonded with control PF and MF. Although there are no actual reaction at all between PF, MF, and tannin, addition of tannin significantly improves the water resistance of PF and MF resins. This is a novel finding that manifests the possibility of replacing a convention PF and MF resins by tannin. Modified adhesive is one of the goals in the plywood production without changing any of their production conditions with improvement to their overall properties. 相似文献