PD—3改性中温合成脲醛树脂的探索

本文介绍了ＰＤ－３改性中温合成脲醛树脂的合成工艺，用２０％ＰＤ－３改性的脲醛树脂生产中的中密度纤维板，甲醛释放量可满足欧洲Ｅ２级标准。     

PD－3改性中温合成脲醛树脂的探索

本文介绍了ＰＤ－３改性中温合成脲醛树脂的合成工艺，用２０％ＰＤ－３改性的脲醛树脂生产的中密度纤维板，甲醛释放量可满足欧洲Ｅ２级标准。     

中密度纤维板真空热处理

中密度纤维板真空热处理旨在降低中密度纤维板甲醛释放量，并改进中密度纤维板性能。研究结果表明，在温度为６０℃、真空度为６６６６１Ｐａ（５００ｍｍＨｇ）的真空和加热条件下，中密度纤维板的甲醛释放主要集中在最初的２￣４ｈ内；甲醛释放量显著降低，同时板材的力学性能提高约１０％。     

三聚氰胺改性脲醛树脂胶粘剂在中密度纤维板上的应用研究

耐水性差、游离甲醛释放量高是我国中密度纤维板（ＭＤＦ）存在的两个主要问题。用三聚氰胺改性脲醛树脂（ＭＵＦ）胶粘剂生产ＭＤＦ可以有效地提高耐水性，降低游离甲醛释放量，并使得因管道施胶引起预固化问题得到有效控制。     

低毒改性脲醛树脂胶粘剂的研究

应用胶体理论,在树脂合成过程中期加入改性剂,改性剂添加量为3％,合成了性能良好的低毒改性脲醛树脂 胶。使原料成本降低8％,且树脂胶贮存稳定性好。压制的中密度纤维板,甲醛释放量达到了E1级。     

用不脱水低摩尔脲醛树脂制造低游离甲醛刨花板与中密度纤维板

试验结果表明差示扫描量热仪 (DSC)能够测得NLFS - 1型捕捉剂与甲醛反应 ,并且这种捕捉剂能够捕捉脲醛树脂胶中的大部分游离甲醛 ,其捕捉量与树脂的摩尔比或游离甲醛量有关。对于低摩尔比 ,不脱水脲醛树脂刨花板和中密度纤维板 ,仅用 5 %捕捉剂就能获得较高的捕捉能力。这些板的游离甲醛释放量均能达到欧洲E1级或国标GB -T11718- 1999A级标准。刨花板后期热处理 ,对板的内结合强度提高明显 ,但板的甲醛释放量略有增加     

环保高防潮纤维板用改性脲醛树脂胶黏剂的研制

介绍一种三聚氰胺改性脲醛树脂胶黏剂制备工艺,甲醛与尿素的摩尔比为1.0∶1,三聚氰胺添加量为11%。合成的改性脲醛树脂胶黏剂耐水性好且低毒环保,用其压制的中纤板性能满足GB/T 11718-2009《中密度纤维板》对高湿度状态下的家具型板材的使用要求,甲醛释放量达到GB 18580-2001《室内装饰装修材料-人造板及其制品甲醛释放限量》E1级环保要求。     

应用甲醛捕集剂压制环保型中密度纤维板

介绍了中密度纤维板环保的必要性,试验证明应用自制的甲醛捕集剂生产环保型中密度纤维板可行;采用正交试验,得到了合理的环保型中密度纤维板生产工艺参数：热压温度180±5℃、脲胶施加量10％、甲醛捕集剂施加量12％、热压时N25s／mm;压制的板材物理力学性能达到优等品要求,甲醛释放量满足E1级要求。     

浸渍纸饰面和封边对MDF甲醛释放的阻隔效应

采用干燥器法测定用不同浸渍纸饰面和不同材料封边的中密度纤维板甲醛释放量,分析饰面和封边对甲醛释放的阻隔效应,为企业优选浸渍纸和封边形式提供指导;探索饰面和封边对甲醛释放的阻隔机理,为控制中密度纤维板甲醛释放提供科学依据和方法。试验结果表明,饰面和封边可以大大降低中密度纤维板中甲醛向外扩散和蒸发的速率,实现降低中密度纤维板甲醛释放量;就对甲醛的阻隔作用而言,3种浸渍纸中耐磨纸的阻隔效果最差,装饰纸次之,平衡纸最好;而3种不同材料的封边方式对甲醛的阻隔效应是熔融石蜡聚氯乙烯热缩膜铝箔;不同的浸渍纸配置方式对中密度纤维板甲醛释放的影响也不同,饰面层越厚,饰面层越多,对甲醛的阻隔性能就越好。使用100g平衡纸、70g装饰纸和42g耐磨纸饰面中密度纤维板可以作为生产E_0级强化木地板的优选方案。     

中温合成改性低粘度脲醛树脂的试验研究

介绍了中温合成低粘度脲醛树脂的合成工艺。采用20％助剂改性后的脲醛树脂生产的中密度纤维板．其甲醛释放量满足欧洲E2级标准。     

MF—97三聚氰胺—甲醛树脂对中密度纤维板（MDF）耐湿性能影响初探

本文着重介绍了用ＭＦ－９７三聚氰胺－甲醛树脂制备准耐水级ＭＤＦ的结果。     

Utilization of pine (Pinus pinea L.) cone in manufacture of wood based composite

Physical and mechanical properties of medium density fiberboards (MDF) made from various mixtures of wood fibers and stone pine (Pinus pinea L.) cones were evaluated using European standards. MDF panels were manufactured using standardized procedures that simulated industrial production at the laboratory. Six panel types were made from mixtures of wood fiber/cone flour, 100/0, 90/10, 80/20, 70/30, 60/40, and 50/50 percents, respectively. Addition of the cone flour into the MDF significantly reduced formaldehyde emission from the panel. In addition, the addition of 10% cone flour also improved water resistance of the MDF panels made using urea–formaldehyde (UF) resin. However, further addition of the cone flour into the panel negatively influenced their water resistance. Flexural properties and internal bond strength decreased with the increase of cone flour content in the panel. The UF resin is the main source of formaldehyde emission from the UF-bonded wood-based panels. Depending on addition of the cone flour in the panels, the formaldehyde emission values ranged from 2.6% to 55.3% lower than the panels made from 100% wood fiber. Based on the findings obtained from this study, pine cone can be used as a renewable biological formaldehyde catcher as an alternative to the traditional formaldehyde catchers for E1 Class MDF manufacture.     

Property of nano-SiO2/urea formaldehyde resin

In this paper, we discuss the effects of a nanometer silicon dioxide (nano-SiO₂) coupling agent, dispersal methods and the amount of nano-SiO₂/urea formaldehyde resin. The results of our study indicate that when nano-SiO₂, using KH-550 silane as a coupling agent, was added to UF resin by discontinuous ultrasonic vibration, its properties improved effectively. When the content of nano-SiO₂ was below 1.5%, the amount of free formaldehyde decreased, and the viscosity and bonding strength of resin increased with an increase in the added nano-SiO₂, which did not prolong the curing time. The performance indices of plywood, particleboard and medium density fiberboard (MDF), hot-pressed by nano-SiO2 (1%)/UF resin (F/U molar ratio=1.2), exceeded the requirements of the National Standard. Their free formaldehyde emission reached E1 grade. Finally, we analyzed the mechanism of the strengthening effects of nano-SiO₂ on UF resin by means of infrared spectrum analysis and X-ray photoelectronic spectrum (XPS). __________ Translated from Scientia Silvae Sinicae, 2005, 41(2) [译自: 林业科学, 2005, 41(2)]     

高支化聚脲对脲醛树脂胶黏剂耐水性能和甲醛释放量的影响

引入高分子量、高支化度以及端基为尿素的高支化聚脲(HBPU)用于低摩尔比脲醛树脂(UF)改性,利用HBPU与游离甲醛的反应以及与UF组分的共缩聚反应实现树脂耐水性能的提升和人造板甲醛释放量的降低,有效平衡胶合性能和甲醛释放量之间的矛盾。在无溶剂、无催化剂条件下,通过尿素(U)与三(2-氨基乙基)胺(TAEA)的脱氨缩合反应,一步合成了具有尿素端基的HBPU,并对HBPU的分子量分布和结构进行了表征。使用HBPU水溶液,采用UF合成反应后期加入和共混2种方法对UF进行改性,通过胶合板性能测试以及甲醛释放量测定,考察了HBPU添加量和添加方式的影响。凝胶渗透色谱和碳-13核磁共振分析表明,通过本研究的合成方法可以获得具有高分子量、高支化度、尿素为端基且水溶性良好的HBPU,并且随着U与TAEA摩尔比的提高,更多尿素封端产物形成。电喷雾电离质谱对改性树脂的分析结果表明,HBPU不仅与UF中的一部分游离甲醛发生羟甲基化反应,同时与UF组分反应生成了部分共缩聚产物。胶合板性能测试结果表明,共混以及反应后期加入HBPU两种方式得到的改性树脂耐水性能均显著提升。同时,使用添加5%HBPU改性树脂制备的胶合板甲醛释放量较未改性树脂制备胶合板降低41%。HBPU改性同步实现胶合性能的提升和甲醛释放量降低的主要原因在于HBPU在提高树脂支化程度的同时,还起到捕捉游离甲醛的作用。解决UF胶合性能和人造板甲醛释放量之间矛盾的关键在于提升树脂的支化程度,同时降低树脂中游离甲醛的含量,而引入高分子量、高支化度、具有类似尿素反应活性的聚合物是同步实现胶合性能提升和甲醛释放量降低的有效途径。     

LLM型UF树脂制造橡胶木和赤桉中密度纤维板

通过使用ＬＬＭ型ＵＦ树脂制造橡胶木和赤桉中密度纤维板的研究,评价用该树脂制造橡胶木和赤桉中密度纤维板的适应性。橡胶木和赤桉各５０％比例温和后施以ＬＬＭ型ＵＦ树脂,按照ＭＤＦ常规工艺压制９,１２,１６ｍｍ的试验板。结果表明：板材物理力学性能及甲醛释放量指标均达到ＧＢ１１７１８．２－８９标准规定的要求。     

脲醛树脂胶稻草中密度纤维板的性能

通过用稻草代替木材制造脲醛树脂胶稻草中密度纤维板的可行性研究 ,探讨了板材密度、施胶量和防水剂等工艺因素对稻草中密度纤维板性能的影响。结果表明 :在实验室条件下 ,当板材名义密度为 0 .8g/ cm3和施胶量为 17%时 ,脲醛树脂胶稻草中纤板性能达到现行国家标准一等品的要求 ;施加 1.2 %的石蜡乳液 ,板材的耐水性亦能满足国标要求     

纳米二氧化硅/脲醛树脂性能的研究

探讨纳米SiO2 表面处理、加入方式、用量对纳米SiO2 脲醛树脂性能的影响。结果表明 :采用KH - 5 5 0硅烷偶联剂处理纳米SiO2 表面 ,用间歇式超声波震荡法将其加入脲醛树脂中 ,能有效改善树脂性能。当纳米SiO2 用量 <1 5 %时 ,用量越大 ,树脂的胶合强度越高 ,游离甲醛含量越低 ,粘度越大 ,固化时间不变。用纳米SiO2 (用量1% ) 脲醛树脂 (F U摩尔比 1 2 )压制胶合板、刨花板、中密度纤维板 ,板的各项性能指标都超过国家标准要求 ,甲醛释放量达到E1 级水平。同时 ,通过红外光谱和X射线光电子能谱初步探索了纳米SiO2 对脲醛树脂的增强机制     

The ambient aging of wood fiber and its effect on mechanical properties of MDF panels

Fourier-transform infrared (FTIR) spectroscopy and scanning electron microscopy (SEM) were used to study ambient-aged wood fibers and their effects on the mechanical properties of medium-density fiberboard (MDF). It was found that MDF made with ambient-aged fibers had poorer mechanical properties than MDF made with fresh fibers; this difference resulted from the alterations of surface characteristics of wood fibers after ambient aging, which led to poor wettability of the urea–formaldehyde (UF) resin applied to the aged wood fibers. After 6 months of ambient aging, the concentration of carbonyl groups in the fibers increased by 144%, while the pH value of wood fiber decreased from 5.2 to 4.7. SEM showed that much more UF resin agglomerated on the surface of ambient-aged fibers and the breakage of MDF made with aged fiber frequently occurred at the resin-fiber interfaces, indicated the poorer wettability of UF resin to fibers due to the decrease in surface energy after aging.     

用异氰酸酯胶生产中密度纤维板的尝试

以异氰酸酯为胶黏剂,进行了2种原料的中密度纤维板(MDF)生产试验,分析其生产工艺的特点,并根据我国国标及日本相关标准,对板材的性能与甲醛释放量等指标进行检测。结果表明:用异氰酸酯制造的MDF,其各项指标均优于UF胶的MDF,是一种应用前景广阔的环保板材。     

Development of a novel polyvinyl acetate type emulsion curing agent for urea formaldehyde resin

High formaldehyde emission and poor water resistance are two main disadvantages of urea formaldehyde (UF) resin. For that reason, a novel polyvinyl acetate (PVAc) type emulsion curing agent was developed in this paper. PVAc type emulsions, including PVAc, the co-polymer of PVAc and N-hydroxymethyl acrylamide (PVAc–NMA), and the ternary co-polymer of PVAc, NMA, and urea (PVAc–NMA–urea), were the main components. Water, aluminum chloride, ammonium dihydrogen phosphate, polypropylene glycol, silicone oil, and urea were the other components. Under heating, aluminum chloride and ammonium dihydrogen phosphate often underwent thermal decomposition and hydrolysis in solution, produce free acid to cure UF resin, so the curing agent could enhance the curing rate, and then shorten the curing time. In this curing agent, ammonium dihydrogen phosphate and urea worked as formaldehyde removers and reacted with free formaldehyde in UF resin, thus the formaldehyde emission exuded from the plywood could be effectively limited and reduced. The bonding strength of plywood was not improved very much, especially the dry bonding strength, but the wet bonding strength was little enhanced for the active hydroxymethyl group contained in PVAc–NMA and PVAc–NMA–urea underwent a self-cross-linking reaction to improve the bonding strength and adhesion force to the bonded substrate. More importantly, the results from the industrial production experiments were shown to be very good.