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1.
低毒脲醛树脂胶粘剂在E1级胶合板中的应用   总被引:1,自引:0,他引:1  
在低毒脲醛树脂胶粘剂合成过程中加入淀粉或氧化淀粉,能有效地改善胶合板板坯的预压性能和胶合板的胶接强度.当淀粉、氧化淀粉加入量为合成低毒脲醛树脂胶粘剂所用尿素量的30%~40%时,达到较好的使用效果.通过在低毒脲醛树脂胶粘剂调制过程中加入低成本API对低毒脲醛树脂胶粘剂进行改性,亦能改善胶合板板坯的预压性能和胶合板的胶接强度.试验表明,随着低成本API加入量的增加,胶合板的预压性能、胶接强度都有明显提高.考虑成本原因,低成本API的加入量为3%~10%即可达到较好的使用效果.改性低毒脲醛树脂胶粘剂能适应多层胶合板的生产。  相似文献   

2.
在低毒脲醛树脂胶粘剂合成过程中加入淀粉或氧化淀粉,能有效地改善胶合板板坯的预压性能和胶合板的胶接强度。当淀粉、氧化淀粉加入量为合成低毒脲醛树脂胶粘剂所用尿素量的30%~40%时,达到较好的使用效果。通过在低毒脲醛树脂胶粘剂调制过程中加入低成本API对低毒脲醛树脂胶粘剂进行改性,亦能改善胶合板板坯的预压性能和胶合板的胶接强度。试验表明,随着低成本API加入量的增加,胶合板的预压性能、胶接强度都有明显提高。考虑成本原因,低成本API的加入量为3%~10%即可达到较好的使用效果。改性低毒脲醛树脂胶粘剂能适应多层胶合板的生产。  相似文献   

3.
3.胶头的硬度规格 胶头硬度是在制作胶头时配料中所添加的硅油量的多少有关,一般应用在溶剂型油墨中的胶头配料中添加的硅油量是不多的。胶头中,硅橡胶与硅油的比例,有60%:40%~100%:0%,这些比例的变化就可以制作出肖氏硬度为50°~40°,40°~30°,30°~20°等硬度不同的胶头来。其硬度会影响印刷质量和印刷中胶头的使用寿命,硬胶头的印刷效果好、寿命长(例如承印面曲率大的工件等)。  相似文献   

4.
近年来,为提高平装书刊的装订质量,书刊印刷企业普遍采用和推广了胶订工艺。胶订工艺以其工艺流程短,出书快、书本平整美观、装订质量稳定、生产效率高而受到各书刊印刷厂的青睐。目前,胶订书刊在整个出版发行数量中已占有越来越大的比重。胶订工艺是一种利用胶粘剂作联接材料将书帖联结、使其成为册的一种平装书籍加工装帖方法,所用的胶粘剂即热熔胶是一种100%可熔性聚合物固体,经加热熔融到一定温度(一般在160℃~180℃),达到所需的流动性和粘附力时,通过涂胶轮将胶液按一定的胶层厚度、刷胶长度、正确起始位置涂抹到…  相似文献   

5.
鞋博士信箱     
一般来说,胶粘鞋的开胶主要由以下原因造成:1、粘附破坏。在帮脚和外底这两个被粘物中,只有某一个被粘物的粘合面上有胶粘剂、且胶粘剂与该被粘物粘合牢固,而另一个被粘物的粘合面上无胶粘剂或大面积缺胶(如图1A所示)。因此,开胶的根源在无胶粘剂的部件上,即该部件的粘合面未经处理(包括砂磨起绒和处理水处理)或处理程度不足;砂磨起绒后粘合面未进行除尘净化;刷胶前干燥处理程度不足,使部件的含湿量大;刷胶前粘合面上有与胶液不相容的物质或其它隔离物;胶粘剂浓度过大或刷胶方法不当而产生浮胶等。2、內聚破坏。两个被粘物的粘合面上都有胶粘剂,且  相似文献   

6.
段瑞华  翁祥港  赵鹏  帅李 《中国造纸》2023,42(10):118-124
木质素作为自然界中储量最丰富的天然酚类聚合物,是制备酚醛树脂胶黏剂原料中苯酚的潜在替代品。本文分析了工业木质素分离过程中,木质素结构和反应活性的变化,总结了工业木质素预处理或改性的理化方法,并概括了利用改性工业木质素合成的木质素基酚醛树脂胶黏剂的应用性能,最后对开发高木质素取代率和高性能的木质素基酚醛树脂胶黏剂的前景进行了展望。  相似文献   

7.
徐若愚  张静  龚方红 《中国造纸》2011,30(10):24-27
制浆黑液中的降解木质素含有酚羟基结构,可以替代部分苯酚制备酚醛树脂.以NaOH为催化剂,采用二次缩聚法制取酚醛树脂胶黏剂.实验表明,当黑液添加量为15%时,胶黏剂的黏度比空白实验增加1倍,游离甲醛含量降低了27%,胶合强度提高了13.2%.红外光谱分析表明,黑液中的木质素与游离甲醛反应生成有羟甲基的物质,该物质能与酚醛树脂胶粘剂中的物质发生反应,从而既降低了甲醛含量又提高了胶黏剂的胶合强度.  相似文献   

8.
人造板产品游离甲醛问题的思考   总被引:2,自引:0,他引:2  
新世纪来临之际,林产品工业正发生着史无前例的变化,人造板工业也在不断飞跃发展和更新。有资料预测,21世纪前10年,我国人造板产量将达3000万m3。世界木材工业用胶粘剂约占总胶粘剂产量的70%。而木材工业用胶中,脲醛树脂胶将占到65%-70%。  相似文献   

9.
人类采用胶粘剂进行胶接已有数千年的历史,而合成胶粘剂的发展仅是本世纪二十年代的事情。从原料来看,以高分子材料为主要原料的胶粘剂约占胶粘剂总数的80%,而氯丁胶粘剂又占橡胶胶粘剂的80%;就品种而论,仅美国胶粘剂品种就有五十种以  相似文献   

10.
BL-甲醛消纳剂具有低成本、降醛效果明显、本身环保无毒、使用方便等优点。试验结果表明:当BL-甲醛消纳剂添加量为1%时,刨花板的甲醛释放量降低达40%~75%,力学性能保持基本不变,且符合GB/T4897—92刨花板国家标准要求;胶粘剂的凝胶时间有所缩短。  相似文献   

11.
利用制浆黑液中的碱木素为主要原料,经过羟甲基化改性,甲醛缩合制备纤维板胶黏剂,探索改性木素胶黏剂粘结效果。用正交试验方案设计对碱木素改性、胶黏剂制备工艺进行优化。研究表明:将碱木素进行羟甲基化改性,其活性明显提高。最佳的优化条件:甲醛用量7mmol·g-llignin,pH值10,反应温度70℃,反应时间120min;改性碱木素最佳的加入量比例为20%。用碱木素制备改性木素胶黏剂可利用造纸黑液木素资源,而且具有广泛的应用前景。  相似文献   

12.
Rotary cut beech (Fagus sylvatica L.) veneers were treated with four different lignin phenol formaldehyde (LPF) solutions using dimethyl sulfoxide (DMSO) as a solvent. Four of these veneers were bonded with PF adhesive to produce four-layer laminated veneer lumber (LVL). To synthesize the LPF solutions, a commercial phenol formaldehyde resin (PF resin) was individually mixed with three different technical lignins (Indulin AT, BioChoice lignin, organosolv lignin) and lignin cleavage products (LCP) at a ratio of 3:2 (60%:40%). Differential scanning calorimetry showed an increased curing temperature for the LPF resins in comparison to the PF resin. The mechanical and water-related properties of the LPF-modified LVL were shown to be similar or slightly improved compared to PF-modified LVL. Fungal degradation experiments with white-rot fungus (Trametes versicolor) and brown-rot fungus (Coniophora puteana) exhibited no significant differences in the mass loss of the LPF-modified and PF-modified samples except in one case: LVL made from veneers treated with Indulin AT exposed to the white-rot fungus. The resistance to weathering of LVL samples made from veneers treated with technical lignins was low; however, specimens treated with LCP and the reference PF resin displayed a higher resistance to weathering. It is concluded that technical lignins or LCP can, to a certain extent, be used as a substitute for crude-oil based PF resin.  相似文献   

13.
Suitability of lignin–phenol–formaldehyde (LPF) resoles was investigated for manufacturing paper-based high-pressure laminates. As lignin source, pine kraft lignin and spruce sodium lignosulfonate were compared, substituting 40 wt% of phenol by lignin in each case. The synthesized resins were characterized for their viscosity development, solid content, pH, free formaldehyde as well as free phenol content and B-time. Paper-based high-pressure laminates were manufactured using the two different resins. The laminates were exposed to different test climates and were compared for boiling water resistance, thickness swelling, bending properties and impact energy. The results indicate that pine kraft lignin performs superior to spruce sodium lignosulfonate for utilization in paper based laminates for outdoor usage due to a lower affinity of the pine kraft LPF laminates to water.  相似文献   

14.
木素与酚醛树脂结构相似,可代替部分苯酚制备酚醛树脂胶黏剂。通过对木素胶黏剂的研究现状的系统归纳,介绍了黑液木素制备酚醛树脂胶黏剂的两种方式:一是木素直接替代苯酚,二是木素经活化后再与酚醛树脂结合。合理地利用造纸废液中的黑液木素不仅可以有效地处理大量的造纸黑液,而且可以降低酚醛树脂胶黏剂的生产成本,产生可持续发展的经济效益。  相似文献   

15.
Wood joints bonded with urea-formaldehyde (UF) are weakened by cyclic swelling and shrinking. To study the failure mechanisms in UF-bonded joints, specimens were bonded with unmodified, modified (amine), or phenol formaldehyde adhesive and subjected to accelerated aging. Modification of the adhesive properties increased the cleavage fracture toughness and shear strength of bonded joints and improved the resistance of joints to cyclic swell-shrink treatment and accelerated moist-heat aging. Joints bonded with some modified urea-formaldehyde adhesives were as resistant to these treatments as joints bonded with phenol formaldehyde. Physical and mechanical origins of the improved adhesive performance were determined by microscopic analysis. Cure-shrinkage stresses precracked unmodified adhesive layers and damaged the wood interphase. The damaged interphase was especially susceptible to the effects of cyclic swelling and shrinking stresses. Certain modifiers reduced or eliminated cure-shrinkage cracking and damage to the wood. Moist-heat aging caused molecular scission in the bulk unmodified adhesive layer as revealed by the onset of shear cracking in the adhesive layer and erosion of exposed surfaces. Certain modifiers reduced or eliminated molecular scission and erosion responsible for adhesive weakening in moist-heat aging. We conclude that incorporating flexible amines in the adhesive structure improves the durability and stability of UF-bonded joints.  相似文献   

16.
Adhesive bonding of beech wood modified with a phenol formaldehyde compound   总被引:1,自引:0,他引:1  
Untreated (controls) and phenol–formaldehyde (PF)-modified beech wood (10 and 25?% solid content) were glued with phenol resorcinol formaldehyde (PRF) and polyvinyl acetate (PVAc). Shear strength of PRF-bonded specimens was higher than that of PVAc-bonded ones under dry and wet conditions irrespective of the pre-treatment. Under dry conditions, only PVAc-bonded specimens exhibited reduction in shear strength due to PF-modification with 25?% PF concentration as compared to the controls. PF treated wood provided inferior bonding under wet conditions with the exception of 25?% PF concentration specimens glued with PRF adhesive. Modification with PF resulted in a decrease of adhesive penetration into the porous network of interconnected cells, especially at 25?% PF concentration.  相似文献   

17.
Lignin-Phenol-Formaldehyde resins as adhesives in the production of plywood   总被引:2,自引:1,他引:1  
This paper reports on plywood glued by adhesives based on lignin-phenol-formaldehyde resins. Resin was obtained by polycondensation of sulphate lignin with phenol and formaldehyde in alkali medium. Sulphate lignin was separated from black liquor obtained by delignification of poplar and willow wood.  相似文献   

18.
尿醛预聚体改性木质素絮凝剂对重革废水的脱色效果   总被引:3,自引:0,他引:3  
刘德启 《中国皮革》2004,33(5):27-29
在碱性条件下 ,利用尿、醛对木质素进行共混改性 ,在尿醛的摩尔比为 1∶1时 ,所合成的尿醛木质素絮凝剂用量为 70 0mg/L时 ,色度、COD去除率分别可达到 90 %与 80 %以上  相似文献   

19.
以改性大豆蛋白胶黏剂和杨木纤维为原料,研究了改性大豆蛋白胶黏剂高密度纤维板的物理力学性能,并进行了中试生产试验。结果表明:在热压温度180℃,热压时间40 s/mm,施胶量10%,防水剂加入量1%的条件下,密度0.89 g/cm3的杨木高密度纤维板的物理力学性能可满足LY/T 1611—2003的要求,甲醛释放量满足GB 18580—2001中E1级的要求。  相似文献   

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