One‐component polyurethane adhesives for green wood gluing: Structure and temperature‐dependent creep

Creep and temperature‐dependent creep, characteristic of one‐component polyurethane adhesives for wet and green structural wood gluing are two different parameters. Testing of standards‐approved commercial polyurethane adhesives for this purpose shows that while ambient temperature creep can be avoided or at least greatly limited according to the formulation used, this is not the case for temperature‐dependent creep. The commercial adhesive formulation characteristics that minimize or enhance ambient temperature and temperature‐dependent creep are identified. Basic principles on the structure of simple polyurethane adhesives influencing temperature‐dependent creep are also identified and discussed. The higher the proportion of all hardened network nodes, the lower creep is likely to be at ambient temperature. Instead, due to segment movement and easier disentanglement with increasing temperature, the lower the proportion of covalently linked nodes and the greater the proportion of just physical entanglement nodes, the greater the temperature‐dependent creep will be. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1231–1243, 2005     

基于十字交叉法的陶瓷胶粘剂剪切蠕变性能研究

本研究设计了“十字交叉法”陶瓷胶粘剂剪切蠕变试验装置,选取刚性环氧树脂及柔性硅酮结构胶进行剪切蠕变试验,研究了环境温度、剪切应力、粘结面积等因素对胶粘剂剪切蠕变的影响,通过模型拟合对胶粘剂的剪切蠕变行为进行了分析和预测,探究了两种胶粘剂的蠕变破坏模式。结果表明:采用十字交叉法能够准确便捷地测试陶瓷胶粘剂的蠕变性能。增大胶粘层柔性、提高环境温度、增大剪切应力都会加速蠕变的发展,但粘结面积对蠕变速率无明显影响。刚性环氧树脂胶粘剂试样的蠕变失效形式为粘结层内聚破坏及界面脱粘,符合时间硬化模型;柔性硅酮结构胶试样失效形式为粘结层内聚破坏,符合Burgers模型。     

水性聚氨酯的改性研究进展

聚氨酯胶粘剂作为一类具有良好性能的高分子材料,在很多领域得到应用。水性聚氨酯胶粘剂的问世,满足了日益严格的环保要求。然而水性聚氨酯胶粘剂的耐水性、耐溶剂性、耐候性等较差。本文介绍了目前国内外水性聚氨酯胶粘剂的研究现状及改性方法:交联改性、环氧树脂改性、有机硅改性、多重改性等,并指出了水性聚氨酯胶粘剂的发展趋势。     

聚氨酯胶粘剂的研究进展

综述了聚氨酯胶粘剂的合成、特性和种类。概述了近年来国内外聚氨酯胶粘剂的研究和应用进展,重点介绍了聚氨酯胶粘剂的发展动态和几类主要的聚氨酯胶粘剂,并对其进行了分析,结合实际情况对今后聚氨酯胶粘剂的发展方向作出了展望。     

涂料印花环保粘合剂的研究进展

简述了涂料印花的特点及国内外涂料印花粘合剂的研究现状与发展趋势。详述了新型环保粘合剂(如用无甲醛交联单体、水性聚氨酯、有机硅等进行改性的聚丙烯酸酯类印花粘合剂和水性聚氨酯类印花粘合剂)的聚合体系,具体介绍了聚合工艺的改进,包括核壳乳液聚合、互穿网络乳液聚合以及辐射引发聚合等,对涂料印花粘合剂的研究方向进行了分析。     

国内有机硅改性胶黏剂的研究进展

综述了近年来国内有机硅改性胶黏剂的研究进展,对有机硅改性环氧树脂、丙烯酸树脂、酚醛树脂、脲醛树脂和聚氨酯胶黏剂的制备和性能进行了较为详尽的叙述,展望了有机硅改性胶黏剂的发展前景。     

Creep response of thixotropic ambient temperature cure adhesives measured by DMTA in static tension and shear

The technology for bonding in rods into timber structures for repair, reinforcement and forming primary connections is now well established. An ambient temperature cure adhesive is required for bonding on site and for overhead application thixotropic (shear thinning) characteristics are essential. At the same time bonded-in components may experience service temperatures of 50 °C or more, especially in roof spaces. It is commonly supposed that an adhesive with a glass transition temperature (Tg) below the in-service temperature will suffer from potential creep unless it is tightly cross-linked. In this paper the creep properties of three epoxy-based, thixotropic adhesives are investigated, which are less heavily cross-linked and possess Tg values between 30 and 60 °C. The adhesives are subjected to a creep load in tension within a Dynamic Mechanical Thermal Analyser used in static mode with a step-wise increase in temperature and a range of stress levels. A unique laminated shear specimen has been developed comprising an adhesive layer sandwiched by two thin wood veneers so that the adhesive layer can be stressed in shear. The results demonstrate that in the temperature range between Tg and Tg+15 °C the thixotropic adhesives creep to a limit, behaving as classic viscoelastic polymers and above Tg+15 °C they behave like rubbers with no creep. At high stresses and temperatures the adhesives eventually fail by rupture of the adhesive bonds. In conclusion, thixotropic adhesives are seen to possess a unique combination of physical and chemical properties, which enable them to function above Tg under creep load.     

新型环保涂料印花粘合剂的研究进展

简述了国内外涂料印花粘合剂的研究状况和发展趋势,介绍了制备新型环保涂料印花粘合剂的聚合体系[包括采用无甲醛交联单体、聚氨酯和有机硅等对丙烯酸酯类印花粘合剂进行改性以及合成WPU(水性聚氨酯)印花粘合剂等]和聚合工艺上的改进措施[包括无皂乳液聚合、核壳乳液聚合、互穿聚合物网络(IPNs)乳液聚合以及辐射引发聚合等],并指出了今后涂料印花粘合剂的发展方向。     

J系列胶黏剂在我公司飞机制造中的应用概况

简述了我公司使用的部分J系列胶黏剂的组成、使用工艺、用途、主要性能指标和使用评价。主要胶种包括J-29和J-118发泡胶、J-70和J-122耐腐蚀底胶、J-71和J-123芯条胶、J-116胶膜、J-160单组份改性环氧胶黏剂、J-168耐高温胶黏剂、J-185室温固化氟橡胶胶液、J-189聚氨酯胶、J-190聚合物补偿填充料、J-191环氧胶、J-192胶。该系列胶总体性能稳定,可满足我公司飞机制造要求。     

胶粘剂国内外发展概况

本文综述了胶粘剂国内外发展概况,其中包括市场需要概况,主要工业化品种主要发展趋势和发展建议。涉及的胶粘剂类型有：三醛胶、水基胶、反应型胶、溶剂型胶、热熔胶和橡胶型胶等等。     

Thermal stability of structural one‐component polyurethane adhesives for wood—structure‐property relationship

The relationship between the chemical structure of commercial polyurethanes and temperature‐dependent creep properties was determined in full scale tests and the results were compared with thermomechanical analysis. Comparison of mechanical performance with ¹³C‐NMR spectroscopy studies elucidated important structure‐property relationships, which either allow the reduction or elimination of temperature‐dependent creep in one‐component polyurethanes (1C‐PUR) adhesives for wood. The combination of the relative content of still reactive, free ? NCO groups on the polyurethane, careful selection of the degree of resin polymerization and a slower rate of reaction are the three most significant parameters that have to be controlled to overcome the problem of temperature‐dependent creep found in 1C‐PUR adhesives. The results obtained indicate that adhesives presenting a combination of a higher content of still unreacted ? NCO groups, a lower degree of polymerization and slower reaction rate are capable to counteract problems of high sensitivity of polyurethane to temperature‐dependent creep. Two commercial polyurethanes that fulfil the latter requirements and exhibit almost no creep were identified and characterized. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 5698–5707, 2006     

木材用单组分湿固化聚氨酯胶粘剂的合成

以多亚甲基多苯基多异氰酸酯(PAPI)、聚丙二醇(PPG-N210)和催化剂2,2'-二吗啉二乙基醚(DMDEE)为主要原料合成了一种木材用单组分湿固化聚氨酯胶粘剂,分析了NCO含量、催化剂用量、扩链系数对胶粘剂性能的影响,并与国内外木材用胶粘剂进行了比较。结果表明,NCO质量分数为12.3%、催化剂用量为0.1%、扩链系数为0.2,制得的胶粘剂室温固化且固化速度快,粘接性能较好,适合于木材的粘接。     

Study of Properties of One-Component Moisture-Curable Polyurethane and Silane Modified Polyurethane Adhesives

Abstract

In this paper, the curing behavior and adhesion properties of five kinds of polyurethane (PU) and silane modified polyurethane (SPU) adhesives were studied. Fourier transform infrared spectra showed that the adhesive Sikaflex-555 had an SPU structure and that the other four adhesives were one-component polyurethanes. The experimental results of curing behavior show that the tack-free times and curing rates of these adhesives were significantly affected by the relative humidity and the temperature. The adhesion of the SPU adhesive to glass sheet, zinc galvanized steel sheet and steel sheet was much better than that of PU adhesives. The tack-free times and curing rates of all the adhesives was measured during the 12 months of storage.     

Molecular design and hygrothermal resistance of high-toughness polysiloxane–polyurethane block copolymer composite adhesives

With the development of new energy sources, the demand for aluminum composite films for power batteries is expanding; at the same time, higher requirements have been put forward for aluminum composite films and adhesives. Polyurethane, as the binder of aluminum composite films, strongly affects the performance of aluminum composite films when exposed to moisture and high temperature and can lead to delamination. This thesis prepares a polyurethane and silicone block copolymer composite adhesive by adjusting the ratio of hard and soft polyurethane segments to obtain polyurethane (PU) with excellent flexibility. On the basis of block copolymerization with bis-amino-terminated organosiloxane (ATPS), obtained excellent flexibility, high peel strength, moisture resistance, and heat resistance from a polysiloxane-based polyurethane composite adhesive (PUSR). The properties are also tested using tensile tests and peel strength tests. The test results show that by adjusting the ATPS content, the flexibility and hydrophobicity of the PUSR composite adhesive further improved, with a tensile strength of 36 MPa, an elongation at break of 757%, and bonding performance of 11 N/15 mm. Additionally, the damp heat resistance of 6 N/15 mm, exceeding the international standard of 3 N/15 mm, in the power battery soft package aluminum–plastic film has potential application prospects.     

聚氨酯胶黏剂在汽车上的应用及研究进展

介绍了几种聚氨酯胶黏剂如单组分湿固化聚氨酯挡风玻璃密封胶、双组分聚氨酯胶黏剂、水性聚氨酯胶黏剂、聚氨酯反应性热熔胶等在汽车制造和修理上的应用现状及研究进展，重点介绍了应用最为广泛的单组分湿固化聚氨酯挡风玻璃密封胶。指出汽车用聚氨酯胶黏剂将向环保和高性能方向发展。     

Addition of Urethane-Based Thickener to Waterborne Polyurethane Adhesives Having Different NCO/OH Ratios and Ionic Groups Contents

Several waterborne polyurethane adhesives containing different hard-to-soft segment ratios and ionic groups were prepared by using the acetone process. To improve the rheological properties, a 5 wt% of hydrophobically-modified ethoxylated urethane-based thickener (HEUR) was added. The adhesives were characterized by shear rate-controlled rheology, pH, particle size measurements, solids content and laser confocal microscopy. The adhesive films were characterized by plate–plate rheology, dynamic mechanical thermal analysis (DMTA) and differential scanning calorimetry (DSC). The adhesion properties were measured using T-peel tests of leather/thickened polyurethane adhesive/SBR rubber joints. The addition of the HEUR thickener produced an improvement in rheological properties of polyurethane adhesive dispersions as a result of the physical interactions between the polyurethane particles and the thickener. The addition of the HEUR thickener markedly increased the viscosity of the polyurethane adhesives, as the hard-to-soft segments ratio decreased and the ionic groups content in the polyurethane increased. As the hard segment content of the thickened polyurethane adhesive decreased, the kinetics of crystallization was favoured as a result of stronger polyurethane/thickener interactions. As a result, an improvement in the adhesive strength in the leather/thickened polyurethane adhesive/SBR rubber joints was obtained.     

耐高温有机胶粘剂研究进展

对国内外耐高温有机胶粘剂进行了综述。对环氧树脂、酚醛树脂、聚氨酯、聚酰亚胺、有机硅和氰酸酯等耐高温有机胶粘剂的性能和应用进行了全面讨论,并对其今后的发展趋势进行了展望。     

耐高温有机胶黏剂研究进展

对国内外耐高温有机胶黏剂的研究进展进行了综述。对耐高温有机胶黏剂的定义、种类做了简明阐述。对环氧树脂、酚醛树脂、有机硅、聚酰亚胺、聚氨酯、氰酸酯等耐高温胶黏剂的制备、性能和应用进行了较详细的论述。分别讨论了各种耐高温有机胶黏剂基体树脂的结构和性能特点以及提高上述胶黏剂耐高温性能的改性方法。对聚苯并咪唑和聚喹嚼啉胶黏剂进行了简介。最后,对耐高温有机胶黏剂今后的发展趋势进行了展望。     

Rheological investigation of cure kinetics and adhesive strength of polyurethane acrylate adhesive

In this work, we used rheological techniques to study both the cure characteristics and the degree of cure of polyurethane acrylate adhesive, a type of reactive adhesive used in hard disk component assembly. These results were then correlated with the tensile shear strengths of adhesives. Here, the cure characteristics of polyurethane adhesive were investigated at isothermal conditions ranging from 25 to 120°C. From the rheological results, the gelation time, the vitrification time, as well as the time required to reach the maximum degree of cure, decreased when increasing the curing temperature. The cure rates of adhesive increased with temperature in three temperature ranges, which were retardation zone, vitrification zone, and reaction‐controlled zone. The cure rates in these zones were controlled by slow diffusion, fast diffusion, and the rate of reaction, respectively. From the temperature sweep of fully‐cured adhesives, we found that the crosslinking level of adhesives increased with curing temperatures at different rates depending on the temperature zones as well. Moreover, the adhesive strength measured by tensile shear test was found to also increase correspondingly with the adhesives' T_g, indicating that the crosslinking level directly affected the adhesive strength. The strong dependence of adhesive strength with crosslinking level indicates that the crosslinking level was essential for high adhesive strength. The correlation of cure characteristics and adhesive strengths at various curing temperatures performed in this study can further provide useful information for planning appropriate curing schemes of polyurethane acrylate adhesives used in electronic and other industries. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

水性聚氨酯胶黏剂发展概况

简述可水分散性多异氰酸酯胶黏剂、乙烯基聚氨酯水性胶黏剂和水分散性聚氨酯(PUD)胶黏剂等水性聚氨酯胶黏剂国内外应用和技术发展状况,对我国水性聚氨酯胶黏剂的发展提出初步看法和建议。