Primers for Bonding Polyolefin Substrates with Alkyl Cyanoacrylate Adhesive

Polyolefins, such as polypropylene and polyethylene, are among the most commonly-utilized plastics in the world, but, because of their non-polar surfaces, are among the most difficult to bond with adhesives. A surface treatment is required before adhesive application to achieve good adhesion.

Alkyl cyanoacrylates are widely used instant adhesives, e.g. Super Glue^®, for bonding a variety of substrates, such as metal, plastics, glass, wood, and leather. It would be desirable to bond polyolefins with these adhesives because of their availability and ease of use. Amines and ammonium carboxylates, possessing long alkyl chains, were evaluated as adhesion promoting primers for alkyl cyanoacrylate adhesives on polyolefins.

Among trialkyl amines, trialkylammonium carboxylates, and tetraalkylammonium carboxylates, trialkylammonium carboxylate primers produced an adhesive bond so strong that the failure occurred at the polyolefin substrate. Trialkylammonium carboxylate primers also demonstrated excellent performance retention over prolonged atmospheric exposure prior to application of the adhesive. Trialkyl amines and tetraalkylammonium carboxylates also promoted adhesion but lost maximum effectiveness on exposure to the atmosphere. The cause of the deterioration in amine primer effectiveness over prolonged exposure was identified to be trialkylammonium bicarbonate formation and/or diffusion of the primer into the polyolefin surface.     

Primers for Bonding Polyolefin Substrates with Alkyl Cyanoacrylate Adhesive

Polyolefins, such as polypropylene and polyethylene, are among the most commonly-utilized plastics in the world, but, because of their non-polar surfaces, are among the most difficult to bond with adhesives. A surface treatment is required before adhesive application to achieve good adhesion.

Alkyl cyanoacrylates are widely used instant adhesives, e.g. Super Glue^®, for bonding a variety of substrates, such as metal, plastics, glass, wood, and leather. It would be desirable to bond polyolefins with these adhesives because of their availability and ease of use. Amines and ammonium carboxylates, possessing long alkyl chains, were evaluated as adhesion promoting primers for alkyl cyanoacrylate adhesives on polyolefins.

Among trialkyl amines, trialkylammonium carboxylates, and tetraalkylammonium carboxylates, trialkylammonium carboxylate primers produced an adhesive bond so strong that the failure occurred at the polyolefin substrate. Trialkylammonium carboxylate primers also demonstrated excellent performance retention over prolonged atmospheric exposure prior to application of the adhesive. Trialkyl amines and tetraalkylammonium carboxylates also promoted adhesion but lost maximum effectiveness on exposure to the atmosphere. The cause of the deterioration in amine primer effectiveness over prolonged exposure was identified to be trialkylammonium bicarbonate formation and/or diffusion of the primer into the polyolefin surface.     

触变性氰基丙烯酸酯胶粘剂的开发研究

阐述了触变性氰基丙烯酸酯胶粘剂的合成方法及其优越性。     

表面处理对硅橡胶胶粘剂胶接性能的影响

本文着重研究了不同表面处理条件下硅橡胶胶粘剂的粘接性能。有机硅烷偶联剂对提高硅橡胶胶粘剂的粘接性能有显著效果,其中以GPJ－43的处理效果为最佳。铝合金试样机械打磨后采用不同溶剂清洗对粘接性能也有影响,其中以三氯乙烯的效果为最好。磷酸阳极化是很有效的表现处理方法。对铝－铝粘接界面的分析发现,硅橡胶胶粘剂粘接接头的破坏一般为胶粘剂的内聚破坏或胶粘剂与偶联剂界面的粘附破坏。     

高强度耐热环氧胶带的研制

所研制的是耐热性环氧胶，通过选择基材（包括处理方法）、固化促进剂和耐热性改性剂等，并改进胶带的制法，得到了粘接强度高、耐热性好、使用期长的环氧胶带，选择好的促进剂，不但可以提高固化速度，还可以使胶带具有较长的适用期，先溶解双氰双胺，再将其它组合加入到胶液，得到的胶带的性能较好。     

Zinc Coated Steel/Epoxy Adhesive Systems: Investigation of the Interfacial Zone by FTIR Spectroscopy

The present study takes advantage of the ability of Fourier Transform Infrared Spectroscopy (FTIR) for the analysis of ultrathin organic films on metals. FTIR in the reflection mode (IRRAS) is used in order to study the interaction of ultrathin films of dicyandiamide (hardener of most one-pack epoxy resins) with various substrates, model ones such as gold or zinc and industrial ones such as steel and zinc-coated steels.

Pure zinc surfaces and, to a lesser extent, zinc-coated steels are shown to react with dicyandiamide after heating at 180°C, as evidenced by the frequency shift of the absorption band (at about 2200 cm^-1) characteristic for nitrile groups. As real systems consist of thick layers of a fully formulated adhesive cured onto a metallic substrate, the direct investigation of such a buried interphase is no longer possible by FTIR and by most of the known spectroscopies. Some mechanically tested specimens are then analysed, after failure, by FTIR microspectrometry. The spectra obtained, corresponding to the fracture initiation zone which is about 100 μm in diameter, advocate for the presence of an ultrathin layer of modified polymer still covering the substrate.     

单包装金属—橡胶硫化胶粘剂的研究

介绍一种含全封闭异氰酸胶粘剂的性质。该胶粘剂用于高炭黑填充天然橡胶与金属的硫化粘接时显示出较高的粘合强度、极好的耐湿气性能和热稳定性,同时对金属—橡胶硫化粘接过程中存在的部分问题进行了探讨。     

Structural Adhesive Bonds to Primers Electrodeposited on Steel

Adhesive bond strength and durability were investigated for steel substrates which had been cathodically electroprimed before bonding. Lap shear and torsional impact strengths of two model epoxy adhesives were evaluated. Very poor strengths and durability were found for one adhesive, which was cured with a mixture of three amine curing agents. Scanning electron microscopy and analysis of primer susceptibility to interaction with the curing agents suggested that, for the high concentrations of curing agent in the amine-cured adhesive, chemical and physical degradation of the primer occurred during cure at elevated temperature.

For the second adhesive, which was cured with a single imidazole catalyst, excellent strength and durability were obtained, with no evidence of primer degradation. Surprisingly, for this adhesive, strengths to primed steel were up to 88% higher than to cleaned (i.e., degreased) bare steel. The concurrent improvements in environmental durability over bare steel, as assessed by water immersion and salt spray accelerated exposures, were attributed to the more favourable surface energetics of the adhesive/primer interface.     

含氟聚合物的研究进展

含氟聚合物因其具有优异的化学稳定性、耐热性、电绝缘性、自润滑性、不粘性、耐大气老化性等功能和特点,使其在工业的各个领域得到了广泛的应用。对近五年来含氟聚合物及含氟聚合物乳液的合成及表征的研究现状进行了综述。     

Adhesive Bonding of Clean and Oil-Contaminated Electrogalvanized Steel Substrates

The performance of two-part, amidoamine-cured epoxy adhesives on clean and oil-contaminated electrogalvanized steel (EGS) was studied using screening and lap shear tests. On exposure to boiling water, the cured epoxy adhesives with amidoamines having higher amine value delaminated from the clean and oil-contaminated EGS surfaces before those cured with amidoamines having low amine value. The results of X-ray photoelectron spectroscopy (XPS) showed that the adhesives cured with amidoamines having high amine value were unable to displace the oil from the EGS substrate. However, the durability and the strength of the adhesive bonds on the oiled EGS could be improved by adding proper amounts of silane or wetting agent to the adhesive. The preferential adsorption of amino curing agents occurred on the clean EGS surface, confirmed by XPS and reflection absorption infrared spectroscopy, and this decreased the durability of the bonds in boiling water. In addition, from XPS analyses of various specimens, different amounts of cured resins were detected in the adhesive/EGS interfacial regions which affecting the durability of the adhesive bonds. In addition, the amidoamine curing agents may form complexes on the EGS surface.     

Molecular Structure of Polymer/Metal Interphases

The molecular structure of interphases in aluminum/epoxy and steel/epoxy adhesive joints was characterized using infrared spectroscopy. In one series of experiments, adhesive joints were prepared by curing beams of epoxy against aluminum or steel substrates. When the joints were cooled to room temperature, the residual stresses were sufficient for crack propagation along the interface. The adhesive and substrate failure surfaces were then analyzed with reflection-absorption infrared spectroscopy (RAIR), attenuated total reflection infrared spectroscopy (ATR) and X-ray photo-electron spectroscopy (XPS). When an epoxy/anhydride adhesive was cured against aluminum substrates primed with an aminosilane coupling agent, amide and imide groups were formed in the interphase. Chemical reaction between the primary amine of the primer and the anhydride of the curing agent precluded chemical bridge formation between the primer and adhesive. Metal cations from the 2024 aluminum substrate reacted with the anhydride to form carboxylate salts on the surface. When an epoxy/tertiary amine adhesive was cured against steel substrates, evidence of oxidation of the primary amine to imine was observed in the interphase.     

Molecular Structure of Polymer/Metal Interphases

The molecular structure of interphases in aluminum/epoxy and steel/epoxy adhesive joints was characterized using infrared spectroscopy. In one series of experiments, adhesive joints were prepared by curing beams of epoxy against aluminum or steel substrates. When the joints were cooled to room temperature, the residual stresses were sufficient for crack propagation along the interface. The adhesive and substrate failure surfaces were then analyzed with reflection-absorption infrared spectroscopy (RAIR), attenuated total reflection infrared spectroscopy (ATR) and X-ray photo-electron spectroscopy (XPS). When an epoxy/anhydride adhesive was cured against aluminum substrates primed with an aminosilane coupling agent, amide and imide groups were formed in the interphase. Chemical reaction between the primary amine of the primer and the anhydride of the curing agent precluded chemical bridge formation between the primer and adhesive. Metal cations from the 2024 aluminum substrate reacted with the anhydride to form carboxylate salts on the surface. When an epoxy/tertiary amine adhesive was cured against steel substrates, evidence of oxidation of the primary amine to imine was observed in the interphase.     

The Modification of Epoxy/Metal Interphases by Adsorbed Contaminants

The interfacial region formed between an epoxy/polyamide adhesive and three metallic substrates has been investigated using x-ray photoelectron spectroscopy. The effect of adsorbed contaminants on the interfacial region has also been studied. The substrates studied were cold-rolled steel, electrogalvanized steel and 2024 aluminum. A “ship-out” oil was used to contaminate the cold-rolled steel and electrogalvanized steel whereas an aerospace hydraulic fluid was used to contaminate the 2024 aluminum. Preferential adsorption of the curing agent by the substrates was observed, the effect being most marked in the case of the electrogalvanized steel substrates. The interaction between the galvanized steel and the 2024 aluminum and the curing agent was primarily via the free amines in the polyamide curing agent. In the case of cold-rolled steel the interaction occurred via the amide component. Cold-rolled steel and 2024 aluminum protonated the curing agents. No protonation was detected in the case of the electrogalvanized steel substrates due to the formation of a zinc/amine coordination compound involving the lone pairs of electrons on the nitrogen atoms. When the contaminated cold-rolled steel substrates were studied, the adhesive displaced the majority of the ship-out oil, but no protonation of the curing agent was observed. This indicated that some residual contaminant remained associated with the cold-rolled steel substrate. The majority of the ship-out oil was not displaced from the electrogalvanized steel because the strong preferential adsorption of the curing agent by the substrates created an adhesive layer enriched in epoxy. As the epoxy resin was incompatible with the oil, this epoxy-rich layer acted as a barrier, preventing the absorption of the oil by the bulk adhesive. In the case of the 2024 aluminum substrate, the level of preferential adsorption of the curing agent was decreased, but protonation of the nitrogen groups was still observed. These results indicated that the hydraulic fluid was displaced from the 2024 aluminum in some areas.     

The Modification of Epoxy/Metal Interphases by Adsorbed Contaminants

The interfacial region formed between an epoxy/polyamide adhesive and three metallic substrates has been investigated using x-ray photoelectron spectroscopy. The effect of adsorbed contaminants on the interfacial region has also been studied. The substrates studied were cold-rolled steel, electrogalvanized steel and 2024 aluminum. A “ship-out” oil was used to contaminate the cold-rolled steel and electrogalvanized steel whereas an aerospace hydraulic fluid was used to contaminate the 2024 aluminum. Preferential adsorption of the curing agent by the substrates was observed, the effect being most marked in the case of the electrogalvanized steel substrates. The interaction between the galvanized steel and the 2024 aluminum and the curing agent was primarily via the free amines in the polyamide curing agent. In the case of cold-rolled steel the interaction occurred via the amide component. Cold-rolled steel and 2024 aluminum protonated the curing agents. No protonation was detected in the case of the electrogalvanized steel substrates due to the formation of a zinc/amine coordination compound involving the lone pairs of electrons on the nitrogen atoms. When the contaminated cold-rolled steel substrates were studied, the adhesive displaced the majority of the ship-out oil, but no protonation of the curing agent was observed. This indicated that some residual contaminant remained associated with the cold-rolled steel substrate. The majority of the ship-out oil was not displaced from the electrogalvanized steel because the strong preferential adsorption of the curing agent by the substrates created an adhesive layer enriched in epoxy. As the epoxy resin was incompatible with the oil, this epoxy-rich layer acted as a barrier, preventing the absorption of the oil by the bulk adhesive. In the case of the 2024 aluminum substrate, the level of preferential adsorption of the curing agent was decreased, but protonation of the nitrogen groups was still observed. These results indicated that the hydraulic fluid was displaced from the 2024 aluminum in some areas.     

Regeneration of Adhesive Bonding in Fiber/Resin Systems

The bond between a fiber and a surrounding polymer matrix can be weakened or completely broken by mechanical shearing. In some cases bond strength can be reduced by exposure to active environments (for example, hot water or steam). Obviously, it would be of considerable practical value if weakended or lost bonding could be regenerated. This paper presents the first results of an ongoing study of the possibility of bond repair in fiber/resin systems.

The use of the TRI microbond shear strength measurement technique makes it possible to study bond regeneration with individual fiber/resin specimens. Since the microdrop is displaced only a very short distance along the fiber during the shear strength measurement, it is a simple matter to treat a sheared drop without removing it from the fiber and then perform a second shear strength evaluation. Several systems have been studied in this manner, involving both thermosetting and thermoplastic resins. Examples of significant regeneration of both mechanically-sheared and hydrolytically-weakened bonds are given, and possible mechanisms for the bond strength regeneration are discussed.     

提高环氧胶粘剂耐热性的研究进展

介绍了耐热环氧胶粘剂的主要性能特点,论述了近年来在提高环氧胶粘剂耐热性方面所采用的方法,同时指出了耐热环氧胶粘剂的研究发展方向。     

The effect of a multicomponent silane primer on the interphase structure of aluminum/epoxy adhesive joints

The structure of films formed by a multicomponent silane primer applied to an aluminum adherend and the interactions of this primer with an amine-cured epoxy adhesive were studied using X-ray photoelectron spectroscopy, reflection-absorption infrared spectroscopy, and attenuated total reflectance infrared spectroscopy. The failure in joints prepared from primed adherends occurred extremely close to the adherend surface in a region that contained much interpenetrated primer and epoxy. IR spectra showed evidence of oxidation in the primer. Fracture occurred in a region of interpenetrated primer and adhesive with higher than normal crosslink density. The primer films have a stratified structure that is retained even after curing of the adhesive.     

用X射线仪热分析仪研究影响磷酸氧化铜胶的粘接强度因素

用X射线粉末衍射仪和综合热分析仪对不同固化用具、不同固化温度的YW -Ⅰ磷酸氧化铜无机胶进行较系统分析、研究 ,找出了影响粘接强度的因素。     

苯并恶嗪改性环氧树脂灌封胶黏剂性能的研究

苯并恶嗪作为一种可以中温固化的,无挥发份产生的耐高温树脂,目前在灌封胶黏剂领域还没有被应用.通过苯并恶嗪改性环氧树脂可以提高其耐热能,并保持原有力学性能.制备了一种苯并恶嗪改性环氧树脂灌封胶黏剂.采用红外光谱研究了其固化前后的结构变化,采用差热分析法对其固化行为进行了分析,通过热重法和动态黏弹法研究了其耐热性能.胶黏剂力学性能研究结果表明该体系在130 ℃固化5 h,具有良好的耐热性和力学性能.     

高速商标胶的研制

介绍了一种新型改性的淀粉胶粘剂的制备方法，由淀粉氧化、交联而成，该胶适用于啤酒生产线的高速贴标，它具有好的粘度稳定性和低温贮存稳定性、高固含量、不霉变、成本低等优点。