Novel acrylic pressure-sensitive adhesive (PSA) containing silver particles

Acrylic pressure-sensitive adhesives (PSAs) are generally considered as nonelectrically conductive materials. The electrical conductivity is incorporated into acrylic polymer after blending with electrical conductive additives like silver particles. After the addition of electrically conductive silver filler, the main and typical properties of PSAs such as tack, peel adhesion, and shear strength will decline. This study is the first trial which reveals that the acrylic self-adhesive basis must be synthesized with ameliorated initial performances like high tack and excellent adhesion. Currently, the electrically conductive solvent-borne acrylic PSA containing silver fillers are not commercially available on the market. They are promising materials which can be applied for the manufacturing of diverse technical or medical high performance self-adhesive products, such as broadest line of special electrically conductive sensitive tapes.     

New Developments in the Area of Solvent-Borne Acrylic Pressure-Sensitive Adhesives

Since their introduction half a century ago, acrylic pressure-sensitive adhesives have been successfully applied in many fields. In the last fifty years or so, acrylic pressure-sensitive adhesives (PSAs) have made tremendous strides from what was virtually a black art to what is now a sophisticated science. So much so that larger manufacturers of pressure-sensitive adhesives and even their polymer suppliers now use very expensive equipment to study pressure-sensitive adhesive behavior. The three properties which are useful in characterizing the nature of pressure-sensitive adhesives are tack, peel (adhesion) and shear (cohesion). The first measures the adhesive's ability to adhere quickly, the second its ability to resist removal by peeling, and the third its ability to hold in position when shear forces are exerted. The performances of pressure-sensitive adhesives, such as tack, peel and shear, based on polyacrylates synthesized through co-polymerization of acrylate monomers and formulated in organic solvents mixtures are, to a large degree, determined by the molecular weight of acrylic copolymer, polymerization method and especially by the type and quantity of the crosslinking agent added to the PSA. Newly developed solvent-borne PSAs are used in protective foils, removable and repositionable self-adhesive products, water-soluble PSAs and water-dispersible self-adhesive products, photoreactive UV-crosslinkable self-adhesive tapes, and dual-crosslinkable PSAs for self-adhesive tapes with post-crosslinking potential characterized by enhanced cohesion at higher temperatures. The mentioned water-soluble PSAs, water-dispersible self-adhesive products and photoreactive UV-crosslinkable self-adhesives are synthesized in organic solvents as solvent-borne acrylic PSAs.     

Influence of iron carbide filler in carbon matrix on the adhesive properties of acrylic pressure-sensitive adhesives

Inorganic fillers can improve coating properties, such as scratch resistance and UV stability and can significantly enhance the fillers usability in coatings and realize new market opportunities. In the pressure-sensitive adhesive (PSA) technology the inorganic fillers are used to change the very important properties of pressure-sensitive adhesives, such as tack, peel adhesion and shear strength. In the current study, the above mentioned properties of synthesized acrylic PSA using iron carbide filler in carbon matrix were investigated. The acrylic PSA containing iron carbide filler (Fe₃C,C) was examined with SEM/EDX technique and the PSA adhesive and cohesive properties were examined by using a special strength machine according to AFERA tests. The conclusion is that the application of this kind of fillers allows the manufacturing of self-adhesive materials with moderate adhesiveness and very good removability.     

复合填料/聚丙烯酸酯导电压敏胶的制备与性能

针对导电胶黏剂（ECA）在实用中所遇到填料组分单一、易团聚、对基体力学性能影响较大等问题,本文利用不同组分填料间的架桥、插层等“协同”效应,将一定比例的碳黑（CB）、碳纤维（CF）、碳纳米管（CNTs）、纳米石墨微片（NanoG）复合作为导电填料加入到聚丙烯酸酯压敏胶（PSA）中,采用溶液共混法超声分散,得到填料添加量小、导电性能和力学性能良好的导电PSA。运用多种检测手段对导电PSA的电学性质、微观结构、热稳定性和力学性能进行了分析。结果表明,复合填料组成为CF 3%、NanoG 5%、CNTs 5%（均为质量分数）时,导电PSA的电导率达到3.0×10?2S/cm,180°剥离强度为0.38kN/m。     

Recent Developments on Epoxy-Based Thermally Conductive Adhesives (TCA): A Review

The development of new polymer-based conductive adhesives with specific performances and improved conductivity are increasingly critical for thermally interface material (TIM). Epoxy resins have been widely used as a common interface material for conductive adhesives due to its well-known ability to accept wide range of fillers possibly derived from carbon, metallic or ceramic sources. These conductive fillers with high inherent thermal conductivity, together with a possibility to characterize and manipulate the system, leads to the production of thermally conductive adhesives with higher knowledge content for a number of electronics applications.     

镀铜碳纳米管导电胶的研究

通过化学镀方法制备了镀铜碳纳米管,用透射电镜(TEM)对其表面形貌进行表征;并以镀铜碳纳米管为填料制备了环氧树脂导电胶。结果表明:镀铜碳纳米管上的镀层的质量、填料在树脂中的分散性以及填料的质量分数对于导电胶电性能和黏结性能起着决定因素。     

有机硅压敏胶的研究进展

综述了国内外有机硅压敏胶的研究开发现状,着重分析了溶剂型、高固含量型、非芳香族溶剂型和无溶剂型有机硅压敏胶的特点和组成与性能的关系,并对有机硅的应用前景作了展望。     

Behavior of Pressure-Sensitive Adhesives Filled with Metallized Inorganic Particles

The electrically conductive pressure-sensitive composite adhesives based on acrylic polymer and silver-coated inorganic particles have been investigated in this article. The electrical conductivity of the pressure-sensitive adhesives containing silver coated spherical inorganic particles is lower at the same concentration of the filler in comparison with silver coated inorganic fibers, the strength of adhesive joint to aluminum being higher in the case of the pressure-sensitive adhesive containing silver-coated inorganic fibers. After the thermal treatment the strength of adhesive joint to aluminum of electrically conductive pressure sensitive adhesives increases significantly. The suitable concentration proposition of the silver-coated inorganic filler in the pressure-sensitive adhesive requires a compromise solution of the problem taking into account the ultimate adhesive and electrical properties of the investigated pressure-sensitive adhesives composites.     

树脂型压敏胶的研究进展

对近年来出现的各种类型树脂型压敏胶进行了分类,综述了各类压敏胶的优缺点及改性方法。展望了树脂型压敏胶的应用前景和发展方向。     

Synergistic effect of carbon fillers in electrically conductive nylon 6,6 and polycarbonate based resins

The electrical conductivity of polymeric materials can be increased by the addition of carbon fillers, such as carbon fibers, carbon black, and synthetic graphite. The resulting composites could be used in applications such as electromagnetic and radio frequency interference shielding and electrostatic dissipation. A significant amount of work has been conducted varying the amount of single conductive fillers in a composite material. In contrast, very limited work has been conducted concerning the effect of combinations of various types of conductive fillers. In this study, three different carbon fillers were used: carbon black, synthetic graphite pareticles, and pitch based carbon fiber. Two different polymers were used: nylon 6,6 and polycarbonate. The goal of this project was to determine the effect of each filler and combinations of different fillers on the electrical conductivity of conductive resins. A 2³ factorial design was analyzed to determine the effects of the three different carbon fillers in nylon 6,6 and polycarbonate. The results showed that carbon black caused the largest increase in composite electrical conductivity. The factorial design analysis also showed that combinations of different carbon fillers do have a positive synergistic effect, thereby increasing the composite electrical conductivity.     

Electrically conductive adhesives with a focus on adhesives that contain carbon nanotubes

On the basis of an analysis of results presented in the literature, the currently existing knowledge about relationships between the microstructural and physical properties of hard coatings is discussed. Particular emphasis is placed on the role of microstructural features, such as grain boundaries, nonequilibrium structures, impurities, and texture, in controlling the film hardness. On the basis of an analysis of results presented in the literature, the currently existing knowledge of electrically conductive adhesives (ECAs) is discussed. Particular focus is placed on the results obtained with ECAs that contain carbon nanotubes (CNTs) as conductive fillers. The review is divided in curable ECAs based on epoxy resins, and noncurable conductive hot melts and pressure‐sensitive adhesives based on thermoplastic polymers. More literature results were found for epoxy/conductive filler ECAs than for other adhesives. Confirming the assessments made in a book by Li et al., which refers to nanotechnologies in ECAs, we found that only a reduced number of articles allude to polymer/CNT ECAs. Our analysis of the results includes a study of the balance between the viscosity, immediate adhesion, solidification process, electrical conductivity, and mechanical properties of the adhesives. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

用于药物透皮吸收制剂的压敏胶的新进展

药物制剂的发展很大程度上依赖于药用辅料的发展，一种新型高分子药用辅料的开发将会带动一类新剂型和一大批药物新制剂的发展，药用压敏胶的发展对于药物透皮吸收制剂的发展至关重要，本文主要综述了国内外用于药的透皮吸收制剂的压敏胶的发展现状，包括几种通用压敏胶和压敏胶的最新进展。     

Conductivity of polymethylmethacrylate filled with carbon black or carbon fibres under oscillatory shear

The electrical conductivity of polymer composites containing conductive fillers is strongly influenced by the structure of the particle network. Therefore, the change of this network under deformation in the molten state is of great interest, in order to obtain materials with desirable electrical properties. In this work polymethylmethacrylate containing carbon black or carbon fibres was exposed to oscillatory shear deformations and the electrical conductivity of the materials was measured simultaneously. It was found that the particle networks in the composites filled with carbon fibres were more sensitive to deformation than those of the carbon black composites. The stability of the networks increased with growing amount of fillers. Furthermore, it could be shown that conductive and rheological networks behave completely different under shear deformations.     

Viscoelastic Properties of Pressure-Sensitive Adhesives

Recent studies on the correlation of viscoelastic properties of pressure-sensitive adhesive (PSAs) with industry standard performances such as peel, tack and shear are reviewed and discussed. One notewothy feature in these correlations is the separation of the bonding and debonding steps in PSA adhesion, which specifies the characteristic bonding and debonding frequencies of different PSA tests. Viscoelastic windows (VW) for different types of pressure-sensitive adhesives (PSAs) proposed by these workers are also compared and discussed. The observed good correlations reaffirm the importance of bulk viscoelastic properties to PSA adhesion performances.     

Synergistic effects of carbon fillers in electrically and thermally conductive liquid crystal polymer based resins

Adding conductive carbon fillers to insulating thermoplastic resins increases composite electrical and thermal conductivity. Often, as much of a single type of carbon filler is added to achieve the desired conductivity, while still allowing the material to be molded into a bipolar plate for a fuel cell. In this study, varying amounts of three different carbons (carbon black, synthetic graphite particles, and carbon fiber) were added to Vectra A950RX Liquid Crystal Polymer. The resulting single filler composites were tested for electrical resistivity (1/electrical conductivity) and thermal conductivity. In addition, the effects of single fillers and combinations of two different carbon fillers were studied via a factorial design. The results indicated that for the composites containing only single fillers, synthetic graphite, followed by carbon fiber, cause a statistically significant decrease in composite electrical resistivity. Composites containing only synthetic graphite, followed by carbon black, and then carbon fiber cause a statistically significant increase in thermal conductivity. For the combinations of two different fillers, the composites containing carbon black/synthetic graphite and synthetic graphite/carbon fiber had a statistically significant and positive effect on thermal conductivity. It is possible that thermally conductive pathways are formed that “link” these carbon fillers, which results in increased composite thermal conductivity. POLYM. COMPOS., 2008. © 2008 Society of Plastics Engineers     

Stress Relaxation During Bond Formation and Adhesion of Pressure-Sensitive Adhesives

Relaxation properties and adhesion of pressure-sensitive adhesives (PSAs) have been studied with the Probe Tack method under the conditions corresponding to the adhesive bond formation. Typical representatives of various PSA classes are examined: adhesives based on the styrene-isoprene-styrene (SIS) block copolymer, polyisobutylene of two molecular weights, acrylic and silicone PSAs. By comparison of the adhesive and relaxation behaviors of different PSAs it has been established that the PSA relaxation contributes appreciably to the strength of the adhesive bond and underlies the impact of contact time on adhesion. Direct correlation has been established between the compressive stress relaxation in the course of bond formation and the mechanism of debonding. All the examined PSAs can be classified into two groups: 1) the fluid-like PSAs that are capable of relaxing fully under compression (PIB, silicone adhesives) and 2) the PSAs, which reveal a residual unrelaxed stress. Physically crosslinked SIS and chemically crosslinked acrylic adhesives exemplify the PSAs of the second group. The occurrence of two peaks on the debonding stress-strain curves is typical of the PSAs of the second group. High adhesive strength requires the contribution of the longer relaxation times that vary for different PSAs in the range from 150 to 800 s. Minimum values of the longer relaxation times are featured for fluid adhesives, whereas the maximum values are found for crosslinked, network, and entangled adhesives. The adhesive strength achieves its maximum when the slow relaxation processes become dominating. Relative contributions of viscous and elastic deformations to relaxation properties of PSAs are assessed in terms of the Deborah number.     

Stress Relaxation During Bond Formation and Adhesion of Pressure-Sensitive Adhesives

Relaxation properties and adhesion of pressure-sensitive adhesives (PSAs) have been studied with the Probe Tack method under the conditions corresponding to the adhesive bond formation. Typical representatives of various PSA classes are examined: adhesives based on the styrene-isoprene-styrene (SIS) block copolymer, polyisobutylene of two molecular weights, acrylic and silicone PSAs. By comparison of the adhesive and relaxation behaviors of different PSAs it has been established that the PSA relaxation contributes appreciably to the strength of the adhesive bond and underlies the impact of contact time on adhesion. Direct correlation has been established between the compressive stress relaxation in the course of bond formation and the mechanism of debonding. All the examined PSAs can be classified into two groups: 1) the fluid-like PSAs that are capable of relaxing fully under compression (PIB, silicone adhesives) and 2) the PSAs, which reveal a residual unrelaxed stress. Physically crosslinked SIS and chemically crosslinked acrylic adhesives exemplify the PSAs of the second group. The occurrence of two peaks on the debonding stress–strain curves is typical of the PSAs of the second group. High adhesive strength requires the contribution of the longer relaxation times that vary for different PSAs in the range from 150 to 800 s. Minimum values of the longer relaxation times are featured for fluid adhesives, whereas the maximum values are found for crosslinked, network, and entangled adhesives. The adhesive strength achieves its maximum when the slow relaxation processes become dominating. Relative contributions of viscous and elastic deformations to relaxation properties of PSAs are assessed in terms of the Deborah number.     

Prospective materials for biodegradable and/or biobased pressure-sensitive adhesives: a review

A pressure-sensitive adhesive (PSA) is an adhesive system that is permanently tacky and adheres to a variety of surfaces with light pressure without phase changes. These adhesives are most commonly found in adhesive tapes such as the Scotch® tape or Post-it® notes. The majority of PSAs are petroleum-based products and usually not biodegradable. The amount of waste generated from these products is quite large as these products are considered disposable. The present review focuses on biodegradable elastomers and how they can be useful in PSAs. This review also covers some novel PSA systems that are biobased or biodegradable.     

Cross-Linking of Hot-Melt-Processible Acrylic Pressure-Sensitive Adhesives using Acid/Base Interaction

Hot-melt pressure-sensitive adhesives (PSAs) advantageously reduce or eliminate the use of organic solvents. To provide for easy processing and good coating quality, hot-melt PSAs typically are relatively low in molecular weight, but this can compromise cohesive strength. Physical cross-linking and ionic cross-linking provide thermoreversible methods to increase cohesive strength. This study focuses on the use of acid/base interaction between two polymers as a possible route toward hot melt coatable acrylate PSAs. Adhesive performance and rheological data suggest that a good balance of properties can be obtained while maintaining melt processibility. The rheological data also clearly demonstrate that the strength of the acid/base interaction and the structure of the base have a significant effect on the final properties of the adhesive.     

Relationship between the fracture energy and the mechanical behaviour of pressure-sensitive adhesives

Mechanical behaviours of two pressure-sensitive adhesives (PSAs) families, composed of elastomer copolymers or polyacrylate/acrylic copolymers, are characterised by peel tests. Fracture energy varies linearly according to the applied contact force between two levels, which depends on tackiness and cohesion of the PSA. Local fracture energies are measured by an original peeling system and they are related with the adhesive deformation. Mechanical behaviours of PSAs depend on their composition but majority of fracture energy is dissipated on the first millimetre near the bending zone where fibrils elongation is maximum. Observations of interfaces between PSAs and glass substrate underline that fracture energy varies linearly according to the contact area.