生物质木材胶黏剂的研究进展

综述了几种重要生物质木材胶黏剂即单宁、木素、大豆蛋白、淀粉及木材原料基木材胶黏剂的研究进展情况,分析了生物质木材胶黏剂的应用现状,探讨了生物质木材胶黏剂的研究方向及发展趋势.     

人造板用大豆蛋白胶黏剂研究进展

目前人造板用胶黏剂仍以醛类树脂胶黏剂为主导,存在人居环境甲醛污染和依赖化石资源等问题。随着人们环保意识提高、不可再生资源日益减少以及人造板环保等级要求的不断提升,以生物质资源为原料、水为分散介质的大豆蛋白胶黏剂,作为一种环保、可再生木材胶黏剂显示出巨大的发展潜力,但其耐水胶接性能差等问题仍制约其工业化应用,为木材工业研究热点之一。笔者综述了近年来国内外研究者在提高人造板用大豆蛋白胶黏剂耐水胶接性能方面的研究进展,重点介绍了提高大豆蛋白胶黏剂耐水胶接性能的改性方法,并分析了其改性机制与存在问题,包括蛋白质变性、接枝改性、酶改性、交联改性、大豆多糖改性、仿生改性、纳米材料改性、复合改性等,同时对提高大豆蛋白胶黏剂固体含量、降低黏度、改善抗霉变性能等方面研究进行了综述。探讨了大豆蛋白胶黏剂改性研究方向,并对其科学意义以及应用发展趋势进行了展望,以期为生物质木材胶黏剂的深入研究和在木材工业中的进一步推广应用提供理论与经验指导。     

玉米酒精粕基木材胶黏剂的制备及其性能

以玉米酒精粕(DDGS)为原料、聚酰胺环氧氯丙烷树脂(PAE)为交联剂、水溶性豆粕(SM)为增强剂制备玉米酒精粕基木材胶黏剂,对比了DDGS与SM蛋白质含量及其氨基酸种类与含量,测试了胶黏剂黏度与制备胶合板的胶合强度,表征了固化胶黏剂功能性基团、热稳定性、断面形态,解析了DDGS基胶黏剂组分对性能的影响规律与增强作用机制。结果表明:与SM相比较,DDGS中蛋白含量低46.3%,蛋白质亲水侧链氨基酸含量低22.0%,疏水侧链氨基酸高43.4%,DDGS蛋白溶解性和反应活性低于SM蛋白;当原料m(DDGS)∶m(SM)=3∶1时,胶黏剂制备胶合板耐水胶合强度为0.91 MPa,较DDGS胶黏剂提高727.3%,达到国家Ⅱ类胶合板标准要求,同时原料成本降低29.2%;相比SM胶黏剂,m(DDGS)∶m(SM)=1∶3时,胶黏剂制备胶合板耐水胶合强度提高7.5%,达1.43 MPa,其原因是SM的加入提高了胶黏剂交联密度;胶黏剂黏度降低了32.4%,更容易渗透到木材孔隙中形成机械结合力;DDGS中含有7%纤维,可以对胶黏剂产生物理增强作用,阻碍裂隙延伸,提高内聚力。因此,利用DDGS为原料可有效制备耐水木材胶黏剂并用于胶接人造板,有利于推动蛋白基木材胶黏剂的工业化应用。     

大豆蛋白-丙烯酸酯复合胶黏剂的研究

利用大豆蛋白大力发展绿色环保型胶黏剂,可以降低木材工业界的产品成本和对石化产业的依赖性。大豆基胶黏剂用于刨花板时表现出类似于或优于脲醛树脂胶黏剂的力学性能,这就表明,大豆基胶黏剂可以代替脲醛树脂胶黏剂用于室内建设和家具行业等领域中,从而避免了脲醛树脂胶黏剂中有毒气体的散发。笔者主要是研究配制出符合制造Ⅱ类胶合板用胶,满足其国标,从而达到保护环境、节省不可再生资源和降低成本的目的。通过实验得出2.5g大豆蛋白、10gPVA、36gMMA、0.32gAPS和200g水所制得的改性大豆蛋白胶胶合强度优异,且成本降低。通过正交实验确定出最佳的压板工艺条件:120℃、2MPa、5%固化剂所制得的胶合板为最优异。     

植物酚类PF树脂胶的研究现状及发展趋势

利用植物酚类化合物代替苯酚制备酚醛树脂胶黏剂,可扩大酚类原料来源,降低生产成本,并促进资源的可持续利用.通过对木素胶黏剂、单宁胶黏剂、木材液化产物胶黏剂和木材热解油胶黏剂的研究进展和现状进行系统归纳,指出目前植物酚类化合物胶黏剂存在的问题,并对其发展做出了预测.     

胶黏剂在人造板上的应用现状

分析了胶黏剂在人造板行业的利用情况,阐述了环保型胶黏剂、生物质黏剂及其它胶黏剂的研究进展和应用现状,以期为木材胶黏剂的发展提供了一定的参考。     

利用脱脂豆粉制备木材胶黏剂合成工艺初探

由于世界范围内石油资源的紧缺和传统木材用胶黏剂引发的环境问题,使得木材胶黏剂工业重新重视研发豆基胶黏剂。笔者以脱脂豆粉为原料,以尿素、戊二醛为改性试剂制备复合改性木材胶黏剂。分别探讨了尿素浓度、反应温度、反应时间以及戊二醛添加量对改性胶黏剂胶合性能及耐水性的影响,并采用FT-IR分析复合改性胶黏剂样品中活性基团的变化,探索耐水胶合强度增强机理。通过试验结果分析,在试验研究范围内较优合成工艺参数为:尿素浓度为2.0M、反应时间1.0h、反应温度40℃、戊二醛添加量为2.0%(以脱脂豆粉质量为基准)。经30℃热水浸泡处理后,胶合强度达到0.85MPa。     

国内乳液胶黏剂在木材工业中的应用现状与趋势

乳液胶黏剂具有无甲醛释放、常温快速固化的特性,能够适应当前国内木材工业用胶黏剂的要求。本文介绍木材加工用乳液胶黏剂的种类、改性方法及生产研究现状,在此基础上提出木材加工用乳液胶粘剂的发展趋势。     

单宁基木材胶黏剂的研究进展

在常见凝缩类单宁结构特征基础上,讨论了单宁与醛的反应机理,总结了单宁基木材胶黏剂存在的问题及其解决办法,并综述了单宁基木材胶黏剂的应用研究进展.     

我国木材工业用胶黏剂与胶接技术现状和展望

介绍木材工业使用胶黏剂的种类、性能及其特性,以及我国木工胶黏剂生产应用的现状、存在的问题和发展趋势.从被胶接材料、调配胶技术、胶接的表界面和胶接性能角度出发,提出了木材胶接技术对合理使用胶黏剂和提高胶接效能的重要作用问题.     

我国木材工业用胶黏剂产业现状及发展趋势

在我国木材工业中,三醛胶使用量较大,同时其他胶种的应用领域不仅局限在木材工业,交义较多,不易统计,笔者主要通过分析和总结我国三醛胶产业现状来论述我国木材工业用胶黏剂产业发展趋势,提出了市场需求是推动木材工业用胶黏剂产业发展的原动力的观点。     

Urea-formaldehyde microspheres as a potential additive to wood adhesive

Urea formaldehyde (UF) resins are important for wood industry due to their attractive properties at reasonable price. Particulate fillers added to UF are of interest with regard to improving the functionality of UF and also in terms of reduced UF consumption. To study their potential as filler, solid UF microspheres were synthesized and characterised respecting its morphology, chemical curing and thermal stability. Marigold flower structured spheres with diameters between 5 and 20 µm are presented and application trials demonstrated that high amounts of UF may be replaced by solid microspheres without impairing adhesive bond strength of solid wood bond lines. Fluorescence microscopy showed that microspheres greatly reduce adhesive penetration into the wood substrate, retaining the modified adhesive in the bondline. UF microspheres may thus be considered as viable filler for UF adhesives, particularly with regard to the possibility of endowing them with added functionality like self-healing properties.     

木材工业用淀粉基胶粘剂的研究现状及其展望

我国木材加工行业对胶粘剂的需求量很大,但目前市场上绝大多数都是三醛类胶粘剂,环保型胶粘剂种类很少,而淀粉胶粘剂恰好能较好的解决这一问题.重点综述了国内外木材加工行业用淀粉胶粘剂的研究现状及其优缺点,并在此基础上对其进行展望.     

纳米木粉在木材工业的应用前景展望

纳米技术作为一个新突破点,在木材工业上也将产生新的技术革命.本文就纳米技术在木材工业上的发展及应用前景进行展望,预测未来纳米技术可能对木材工业产生的影响.木材变成纳米尺寸后,木材的材料特异性质、尺寸效应及其变化机理都可能发生变化.当木粉变成纳米的粒度以后,原来木材理化指标都将发生改变.在细粉状态下进行木材液化可以改变木材液化的方式和成本,使木材液化真正工业化.在复杂木雕制品的加工中,采用RPM技术利用CAD直接将纳米木粉形成各种复杂木雕制品,可能开创一种新的木材加工方法.利用纳米木基复合材料和高分子材料细胞结构重组将开创人造板科学研究的新领域.纳米木粉生产的无污染胶粘剂可代替含甲醛的有毒胶,胶粘剂的绿色革命可能从木材的纳米技术开始.木磁材料和木绝磁材料的研究将使磁材料和绝磁材料生产的成本下降,在纳米材料中,纳米木粉的成本可能是最低的.     

Evaluation of decay resistance of wood products made from borax-impregnated wood and bonded with a formaldehyde-free cornstarch and tannin adhesive

? At present, the production of wood composites mainly relies on the petrochemical-based and formaldehyde-based adhesives such as phenol-formaldehyde (PF) resins and urea-formaldehyde (UF) resins, which are non-renewable and therefore ultimately limited in supply.

? This paper concerns the decay resistance of wood products bonded with a new, environment-friendly adhesive derived from abundant and renewable cornstarch and tannin. To improve the total resistance of the composite against both Coriolus versicolor and Coniophora puteana rot fungi, borax (di-sodium tetraborate) was added in proportions of 0.5%, 1% and 2% (w/w) to the cornstarch-tannin adhesives.

? The results show that increasing the concentration of borax in the adhesive decreased the mechanical properties of the composite. The best way to avoid this problem was to use wood impregnated with borax.

? Biodegradation studies were conducted on new composites, first without any treatment, followed by borax at 0.5% aqueous solution treatment. The results show that wood impregnated with borax, in the presence of tannin and sodium hydroxide in the adhesive improves the total resistance of the wood composite against both Coriolus versicolor and Coniophora puteana rot fungi.

     

等离子体改性热塑性树脂薄膜制备环保胶合板试验

为获得无甲醛释放的环保胶合板,将热塑性树脂薄膜(低密度聚乙烯(LLDPE)、聚丙烯(PP)、聚氯乙烯(PVC))用作胶黏剂,并利用空气介质阻挡等离子体对热塑性树脂薄膜进行表面改性处理以提高薄膜与杨木单板的界面相容性,从而获得性能良好的环保胶合板。研究了等离子体处理对胶合板胶合性能的影响,并从等离子体处理对热塑性树脂薄膜表面化学组分及其对胶合板界面形貌的影响分析其胶合机理。结果表明:在等离子体处理功率为4.5 kW、处理时间为8 m/min的条件下处理热塑性树脂薄膜,胶合板的胶合强度得到显著提高,LLDPE/杨木胶合板的胶合强度从0.49 MPa增至0.81 MPa,PP/杨木胶合板的胶合强度从0.65 MPa提高到0.84 MPa,均达到Ⅱ类胶合板标准要求。其中用等离子体处理后PVC与杨木制备的胶合板能满足Ⅰ类胶合板的标准要求,胶合强度达到0.79 MPa。XPS分析表明,等离子体改性热塑性树脂薄膜的表面发生了氧化反应,引入了含氧官能团,提高了薄膜表面极性,有利于提高薄膜与杨木单板之间的相互作用,从而使得胶合板的界面胶合更为紧密,说明等离子体处理后树脂与杨木单板的相容性提高,树脂能在单板表面更好地附着。热塑性树脂薄膜与杨木单板制备的胶合板仅有极微量甲醛释放,其主要源于木材自身,远低于国家标准对人造板甲醛释放限量的要求。研究证明等离子体处理能明显改善热塑性树脂薄膜与杨木单板的界面相容性。     

Adhesive performance of woods treated with alternative preservatives

The extended use of woods treated with traditional or alternative preservatives for exterior applications requires an assessment of wood adhesive performance. This study attempts to evaluate the performance of wood adhesives for woods treated with various waterborne preservatives. Two softwood species, i.e. Korean pine (Pinus koraiensis Sieb. et Zucc.) and Japanese Larch (Larix leptolepis [Sieb. et Zucc.] Gordon) were treated with copper–chrome–arsenic (CCA), CB-HDO, or copper azole (CY), and then bonded with four different wood adhesives such as urea–melamine–formaldehyde (UMF) resin, melamine–formaldehyde (MF) resin, phenol–formaldehyde (PF) resin, and resorcinol–formaldehyde (RF) resin. The performance of these adhesives was evaluated by measuring the dry shear strength of adhesive-bonded wood block on compression. Both UMF and MF resins produced a relatively strong adhesive strength for CY-treated pine and larch woods. The PF resin also produced good bond strength when bonded with either larch wood treated with CY or pinewood treated with CB-HDO. The best result was obtained when the CB-HDO-treated woods were bonded with RF resin. For a better bond strength development, a proper combination of adhesive, preservative, and wood species should be selected by taking into consideration of the characteristics of these three parameters as well as their interactions.     

Gluability of thermally modified beech (Fagus silvatica L.) and birch (Betula pubescens Ehrh.) wood

Abstract

One of the main disadvantages of wood is hygroscopicity resulting from its polar character. The sorption–desorption of water causes unwanted swelling and shrinkage in wood. Thermal modification substantially reduces this inconvenient feature. Unfortunately, the same chemical changes that reduce water sorption alter the polar character of the material and result in poorer wetting of thermally treated wood by waterborne adhesives. Gluability of thermally modified beech (Fagus silvatica L.) and birch (Betula pubescens Ehrh.) wood with two commercial amino resins, melamine–urea–formaldehyde (MUF) and melamine–formaldehyde (MF), and a two-component polyurethane (PUR) adhesive was investigated. Both wood species were modified according to two temperature regimes: 160°C and 190°C. Shear strengths of the joints were then determined according to EN 205:2003 standard. The results showed that thermally modified beech and birch wood can be effectively glued not only with commercially available PUR adhesives, but also with aqueous MF and MUF resins. The resultant shear strengths of the joints were limited by the strength of the thermally modified substrate.