Investigation of Adhesion Performance of Aqueous Polymer Latex Modified by Polymeric Methylene Diisocyanate

Aqueous polymer isocyanate (API), which has good adhesive properties at ambient temperature and excellent resistance to warm/boiling water, and is friendly to the environment, is widely used in the timber-processing industry. To prepare high performance API, vinyl acetate homopolymer and copolymer emulsion were respectively cross-linked by three types of polymeric methylene diisocyanate (p-MDI). The potlife, curing time, bonding strength, and water resistance of API adhesives were tested with different cross-linkers and varying loadings (5-20%). Also the effect of polyvinyl alcohol (PVOH) content of aqueous vinyl latex on the performance of API was investigated. It was shown that the potlife and curing time of API were obviously influenced by the types of cross-linker and its loading. Correct loadings of p-MDI as crosslinker can remarkably improve the adhesive performance of aqueous polymer emulsion at ambient temperature. Excess cross-linker cannot maintain such an effect of strengthening and may decrease considerably the bond properties of API. The warm- and boiling-water resistance of API improved markedly with increasing cross-linker loading, where emulsifiable isocyanate gave better cross-linking performance, and p-MDI mixed with organic solvent was the secondbest. With the increase of PVOH content, the curing time of API increased, but no statistically apparent differences in the potlife of API were found. The bonding performance of API was improved as PVOH content increases, but excess PVOH also weakenes the warm- and boiling-water resistance of the joint.     

Investigation on fracture performance of aqueous polymer isocyanates in terms of energy release rate

In order to investigate the fracture performance of aqueous polymer isocyanates (APIs), an analytical expression for the energy release rate of adhesively-bonded three-point bending specimens has been derived from linear elastic fracture mechanics (LEFM) and the energy release rates of nine API samples are evaluated. Experimental results show that a proper loading of polymeric diphenylmethane-4,4′-diisocyanate (p-MDI) as cross-linker can improve the resistance of aqueous polymer latex adhesive layer to cracking. Excess cross-linker cannot maintain such an effect of strengthening and may decrease considerably the energy release rate of API polymer. When the loading of polyisocyanate is less than the critical value, the polymer cross-linked by aqueous emulsified p-MDI has a higher resistance to cracking. In contrast, polymers modified by p-MDI blended with an organic solvent have much better performance.     

API固化反应过程的特性研究

使用不同性能的多官能度异氰酸酯作为水性高分子异氰酸酯(API)胶粘剂的交联固化剂,当主剂与交联固化剂混合均匀时,考察了不同种类羧基丁苯(SBR)胶乳及不同性能的交联固化剂对胶粘剂在固化过程中的黏度、胶接剪切强度和固化速率的影响,探索了API胶粘剂的固化反应机制,并且利用差示扫描量热(DSC)法研究了API胶粘剂的固化反应速率随温度变化的规律。研究结果表明,SBR-1的适用期达到2h,最大剪切强度为5.5 MPa;交联固化剂的种类是影响API胶粘剂适用期和胶接性能的重要因素,环境温度和胶液调配后的放置时间是影响API胶粘剂固化反应速率的重要因素。     

接触快速固化型水基木材胶黏剂的研究

用PVOH为保护胶,通过乳液聚合制得了带有活性反应基团的聚醋酸乙烯酯乳液,并以此为甲组分,以含有酰肼基团的高分子聚合物为乙组分,制成了可快速固化的接触固化型木材胶黏剂,实现了木材的快速粘接。并对PVOH及酰肼基团的含量对胶黏剂性能的影响进行了研究。结果表明：所制胶黏剂的最佳配比为甲组分中PVOH含量为4．5％,乙组分中酰肼基团浓度为0．8mol／L。     

改性氧化淀粉填充聚乙酸乙烯酯制备API胶主剂

淀粉经氧化后再与尿素缩合改性,作为聚乙酸乙烯酯乳液的填充剂,制备一种胶合板用水性高分子-异氰酸酯胶（API）主剂。实验研究了氧化剂用量、改性淀粉填充量、聚乙烯醇用量以及异氰酸酯用量对胶合板湿强度的影响,确定了较佳的配比,制得了一种低成本、环保的API胶主剂。     

乙烯基乳液-异氰酸酯木材胶粘剂的研究

介绍了一种乙烯基乳液－异氰酸酯木材胶粘剂，探讨了配方中主要成分对胶粘剂性能的影响。该胶具有良好的胶接性、耐水性。     

水性异氰酸酯交联剂/VAE复合胶粘剂的制备与应用

将六亚甲基二异氰酸酯(HDI)三聚体在自制的丙烯酸树脂乳液中乳化,制得水性异氰酸酯交联剂乳液;然后将交联剂乳液与VAE乳液(醋酸乙烯-乙烯共聚乳液)复配,制得木材用胶粘剂。结果表明:当m(丙烯酸树脂)∶m(异氰酸酯)=2∶1、m(水性异氰酸酯交联剂乳液)∶m(VAE乳液)=1∶2、施胶量为300 g/m2和热压温度为110～130℃时,细木工板的胶接强度(0.85 MPa)、横向静曲强度(22.6 MPa)和耐水性(80℃热水中浸泡10 h不开胶)均达到较佳值,并且均符合GB/T 9 846-2004标准。     

木材胶粘剂用丙烯酸酯共聚乳液的研究

研制一种丙烯酸酯共聚乳液配制成水性双组分胶粘剂——丙烯酸酯共聚乳液/异氰酸酯木材胶粘剂,这种水性聚合物—异氰酸酯胶粘剂具有优异的耐水性和耐沸水性能,它是采用在含活性氢原子的聚合物乳液中加入异氰酸酯化合物交联剂的方法合成,用于集成材等木材粘接,可常温快速固化,使用方便、环境友好,具有优异的胶接性能和耐水性能,能够满足日本集成材检测标准和国家林业行业标准。     

PVAc/SiO2纳米复合乳液的性能研究

采用原位乳液聚合法制备了PVAc／纳米SiO2复合乳液,研究了纳米粒子对PVAc粘接强度和耐水性能的影响,并基于纳米压痕试验,分析了PVAc／纳米SiO2复合乳液的力学性能。研究表明,适量的纳米SiO2能显著改善PVAc胶层的粘接强度和耐水性能,并能明显提高PVAc薄膜的弹性模量、硬度及抗蠕变能力。     

单组分高周波固化木工胶的制备与性能研究

以改性VAE(醋酸乙烯-乙烯共聚物)乳液为木工胶的基体树脂、硼酸为增黏剂、异氰酸酯为交联剂和NaCl为抗冻剂等,成功制备出一种可高周波固化的单组分拼板胶。结果表明:当m(硼酸):m(聚乙烯醇)=0.4:10、w(交联剂)=5%和w(NaCl)=1.0%时,木工胶的综合性能较好,其压缩剪切强度超过欧洲DIN EN 204—2001标准;高周波固化木工胶(不必外加固化剂)的后期性能优于常规加压固化木工胶;该木工胶虽可作为某些中软质板材的拼板胶,但其对西南桦等硬木板材的粘接效果相对较差。     

软木专用水性双组分聚氨酯木器清漆的开发

以核壳型丙烯酸羟基乳液及亲水改性的异氰酸酯固化剂,开发了一种专用于软木涂装的水性双组分聚氨酯木器清漆,该涂料VOC低,涂膜干燥后具有优良的附着力、耐水性、耐醇性及抗粘连性等性能,达到软木制品饰面要求。     

Ⅰ型淀粉基API木材胶粘剂的研究

利用复合变性玉米淀粉制备了Ⅰ型淀粉基水性高分子异氰酸酯(API)胶粘剂。以复合变性淀粉乳液、二元酸、聚乙烯醇(PVA)和聚异氰酸酯(PMDI)为主要影响因素,以压缩剪切强度为评价目标,通过正交试验优化出满足JISK6806-1995要求的Ⅰ型淀粉基API胶粘剂的配方,对影响胶粘剂理化性能的因素进行了系统分析。经验证性试验证明,所优化出的最佳配方具有明显的生产可操作性,交联剂PMDI可不经封闭直接使用,完全能满足现有的木材胶合制品的生产工艺要求,其原料成本为同类进口胶粘剂的1/3,具有明显的社会环境效益和经济效益。     

用于JS防水涂料的醋丙乳液的合成

通过对一种醋丙型防水乳液共聚配方的研究,在乳液反应过程中添加AP-02保护胶和交联单体N-羟甲基丙烯酰胺、A171有机硅氧烷、丙烯酸-2-羟丙酯对醋丙乳液进行改性,提高了乳液的耐水性能、粘结强度和抗拉强度;调胶时,加入分散剂DA-02,保证水泥粉在乳液中更好地的分散。并综合各方面因素对乳液性能的影响,得出了最优配方,即w(AP-02)=1.2%(乳液总量)、w(A-171)=0.7%(单体总量)、w(NMAM)=2.0%(单体总量)、w(DA-02)=2.0%(乳液总量)时,得到醋丙型乳液可以满足聚合物水泥防水涂料的要求。     

Rheological and curing behavior of aqueous ambient self‐crosslinkable polyacrylate emulsion

An aqueous ambient crosslinkable polymer acrylic (AACPA) emulsion was obtained by adding adipic acid dihydrazide (ADH) to the polyacrylate emulsion incorporating diacetone acrylamide (DAAM), and this emulsion was synthesized by two feeding materials methods. The AACPA emulsion and its paint film were characterized with rheological measurements, laser light scattering, Fourier transform infrared, torsional braid analysis (TBA), DTA, and so on. The results showed that AACPA emulsion was pseudoplastic fluid and pseudoplasticity increased with increasing of DAAM content. The results also showed that water resistance, solvent resistance, and thermotacky temperature of AACPA paint film increased with increasing of the content of DAAM. The results dealing with curing behavior of the paint film showed that adding organic swelling solvent and organic acid to the AACPA emulsion can accelerate the curing speed of the paint film. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

API胶主剂-改性聚乙酸乙烯酯乳液的研制

用共聚方法对聚乙酸乙烯酯乳液进行改性，研究了共聚单体、助剂以及改性淀粉作为添加剂对乳液性能的影响。确定了相对较佳的配比方案，合成了一种胶合板用水性高分子-异氰酸酯（API）胶主剂。用异氰酸酯作API胶的固化剂，测得胶黏剂对木材的湿胶合强度达到1．3MPa以上，胶合板的甲醛释放量仅为0．0144mg·L^-1。实验得到了一种耐水性好、低成本、环保的API胶用主剂。     

水性木材胶粘剂的制备与性能研究

以PVA(聚乙烯醇)的醇水溶液、羟基丙烯酸酯乳液为主要原料,制得API(水性高分子-异氰酸酯)胶粘剂的主剂;然后以PAPI(多亚甲基多苯基多异氰酸酯)、DOP(邻苯二甲酸二辛酯)为主要原料,制得API交联剂。研究结果表明:PVA水溶液中有乙醇存在时,能有效提高API胶粘剂的胶接强度;当主剂中m(PVA醇水溶液)∶m(羟基丙烯酸酯乳液)=60∶30、m(水)∶m(乙醇)=78.5∶21.5和m(主剂)∶m(交联剂)=100∶15时,API胶粘剂的胶接强度和耐水性俱佳,并且其成本相对较低。     

环保型水性聚氨酯复膜胶的开发及其在软包装中的应用

合成出不同结构的水性聚氨酯(WPU)复膜胶,以PET镀铝膜(VMPET)、双向拉伸聚丙烯(BOPP)和聚乙烯(PE)为复合薄膜,探讨了聚酯结构对WPU复膜胶粘接性能的影响,分析了异氰酸酯、水性固化剂和外加溶剂等对WPU复膜胶剥离强度和干燥速率的影响。结果表明:以混合聚酯、芳香族异氰酸酯为主要原料,配合水性固化剂,合成的WPU复膜胶对多种复合薄膜具有较好的粘接性能,其平均剥离强度达到3.48N/15mm;添加少量易挥发的无害溶剂,能够提高水性复膜胶的干燥速率,其最大复合速率达到110m/min,并且完全满足工业化的生产要求。     

Improvement of water resistance of wheat flour-based adhesives by thermal–chemical treatment and chemical crosslinking

A water-resistant adhesive for plywood panels for engineered wood floors was developed using thermal–chemically treated wheat flour (WF), polyvinyl alcohol (PVA), and polymeric diphenylmethane diisocyanate (p-MDI) as the cross-linker. The thermal–chemical treatment was performed at 100°C in the presence of sulfuric acid or sodium dodecyl sulfate (SDS). Fourier transform infrared spectroscopy, X-ray diffraction spectroscopy, and scanning electron microscopy were used to investigate the chemical structure, crystalline degree, and morphology change, respectively, of the thermal–chemically treated WF. The boiling water-insoluble content and acetaldehyde values of the thermal–chemically treated WF were also evaluated and compared with those of the controls—native WF and thermally treated WF alone. The bond property evaluation showed that the water resistance of the thermal-SDS-treated WF (T-SDS-WF)-based adhesive was significantly improved, which is mainly attributed to the formation of a three-dimensional crosslinking network resulting from self-crosslinking of the wheat protein, the Maillard reaction between the wheat starch and wheat protein, and the increased crosslinking between T-SDS-WF and p-MDI. Overall, the developed WF-based adhesive is a promising bio-based candidate in the production of plywood for engineered wood floors.     

水性聚合物乳液-异氰酸酯胶粘剂适用期测试方法研究

在综述双组分粘合剂适用期现有测试方法的基础上,提出了一种新型、简捷且精度较高的“体积-时间曲线”法,实验测量了4组水性聚合物-异氰酸酯胶粘剂的适用期,并与相关标准进行了比较。     

一种环保型水性聚氨酯胶粘剂的制备与性能研究

以聚酯多元醇、二苯基甲烷二异氰酸酯(MDI)和二羟甲基丙酸(DMPA)等合成了水性聚氨酯胶粘剂。对含有亲水性羧基的高分子聚氨酯的制备过程进行了分析,实际应用结果表明:要合成性能优异的水性聚氨酯胶粘剂,需要采用水性聚氨酯乳液、固化剂、无机填料和助剂,这种高级材料制备的聚氨酯胶粘剂外观好、剥离强度强;将NMP作为溶剂,能够提高预聚体反应效率;如果要得到外观较好的半透明乳液,预聚体中DMPA用量必须控制在6%~8%左右,这些研究成果具有明显的理论和实际意义。