To most European, notably German automotive OEM, the „DIESEL-Gate“ caused an unexpected turnaround towards emission claims and emission reduction on CO2 and electric mobility in general, the more so since the general public was shocked and got fundamentally critical towards honesty and basic trust of this industry, and even politics switched from low co-operative gear to increasingly opposing overdrive. For sure upcoming is in Europe the fixed emission maximum per fleet of just 95 grams of CO2/km (which translates into 4 liters of gas consumption/per 100km) in 2021, the ban of Diesel powered cars from 2024 onwards inside the Peripherique area of Paris, followed by other EU cities like Oslo and Stockholm; furthermore a minimum EV and hybrid quota for then EU-27 of at least 15% by 2030, and most likely but still pending Diesel bans in a number of German cities like Munich, Stuttgart, Düsseldorf and Hamburg.
Outside Europe China is even more ambitious having set a minimum quota of EV and hybrid at 15% by 2019, and a maximum average fleet consumption of fuel to 5l/100 km from 2020 onwards. In the USA CAFE standards will require for passenger cars by 2025 a fleet average emission of maximum 143 grams of CO2 per mile, or a mere 89 grams/km, given, however, that Mr. Trump does not sack it in-between. Japan and South Korea will also toughen emission and mileage requirements, thus we see a sharply rising legal pressure on automotive OEM to really focus and concentrate on lightweighting for gaining better fuel efficiency, and to concentrate on EV and combined hybrid range-extending technology! Strange enough today and tell tailing for Germany’s automotive OEM is for instance the fact that presently Germany’s Yellow Mail (Deutsche Post) is largest producer for exclusively e-driven micro trucks in that country utilized for mail delivery in inner cities, and in future for many other commercial uses as well. On EV they, not DAIMLER, BMW and/or VW/AUDI compete with TESLA on the global market today, nor have they learned so far from TOYOTA, NISSAN and some Chinese OEM like BYD what EV and hybrid mobility is really all about. This includes the fuel cell option that was first optimized for transportation purposes by DAIMLER, but later-on abandoned and taken over by the Japanese, who concentrate on liquid Hydrogen, however, instead of using LNG as much cheaper & more convenient low emission power source.
Nevertheless, the established OEM will either quickly learn by committing themselves to energy storage and e-mobility, or ultimately take the faith of NOKIA, BORGWARD, GRUNDIG or TELEFUNKEN going down the drain. High annually repeating fines will be charged to those OEM if they miss the then valid emission standards and EV quota, thus time is running short, and that is excellent news for automotive A&S, plus for injection and potting resins all associated with the quickly forming transition to electric mobility ranging from high energy storage batteries to a dense network of charging points to further increase of wind energy harvesting. In fact EV in future will play a vital role in balancing supply & demand of electricity – a benefit often over-lookedeven by experts when discussing EV.
In my presentation I will in detail analyze how this over-all scenario translates in A&S plus potting resin demand, what their specific quality requirements actually are, and what type of unmet needs still have to be addressed quickly by A&S formulators for ensuring best performance. One critical example will be Maintenance, Repair and Overhaul (MRO) during normal vehicle service, and the need for battery and vehicle recycling at the end of service life. And here revers bonding or “disbonding-on-command” becomes a rejuvenating and indispensable requirement. Any chemical and/or physical technology that helps to provides safe answers will be welcomed and guaranty a true market success. More details will be given during my presentation and in the hopefully vibrant discussion to follow.
Polyurethanes have been used for many years to produce high-performance materials. Croda offers biobased polyols that bring excellent durability and high flexibility, while ranging from soft to high-strength, depending on the application need. The bio-based polyols are valuable for reactive polyurethane adhesives and thermoplastic hot-melts.
The polyols allow durability and extreme performance while enhancing the product sustainability. These polyols are based on natural oils with enhanced wetting and flow on the substrate and offer lasting (low temperature) flexibility. The hydrocarbon character imparts water repellency and affinity for a wide range of substrates, including plastics, composites and metal, which is required for lightweight design. Furthermore, the bio-based polyols offer a unique combination of hydrolytic, thermo-oxidative and UV stability, which is highly relevant for demanding automotive applications like bonding under the hood, sealing of electronics and sensors or adhesion in displays.
Epoxy adhesives are used for structural bonding of automotive body parts. Croda offers B-Tough reactive toughening agents to enhance impact performance while adding moisture resistance to the bond. In case waterborne adhesives are preferred for VOC-reduction and environmental reasons, polymeric surfactant Maxemul 9107 can be used to allow dispersing the polymer resin into water.
With these ingredients, adhesives can be used to enhance sustainability, allowing lightweight, durability and solutions for electrical and self-driving vehicles.
Why is adhesives technology gaining greater scrutiny now? Because car manufacturers are more and more turning towards polymer-based composites to replace steel and aluminum. This results in a growing need to find effective ways to bond these types of mixed materials to one another. In some applications, adhesives need to provide structure and rigidity, and in others they have to be flexible and pliable – while at the same time providing a nearly unbreakable bond.
Today one of the major challenges to designers of hybrid multi-substrate systems in modern, lightweight automotive car bodies is to overcome the different coefficients of thermal expansion (CTE) when creating bonds between these very different materials that must last for many years. The market needs an adhesive that offers both high strength and high elasticity at the same time.
In answer to this need, Henkel has developed the new adhesive Loctite UK 2015, which is based on a two-component polyurethane technology. This adhesive is ideally suited to bond structural body parts in the assembly line, regardless of whether they are made of fiber-reinforced plastics, e-coated steel or e-coated aluminum.
The successful usage of laser pretreatment of polymeric materials in adhesive technology can be justified by two different phenomena that may occur during treatment:
The constant challenges of car body lightweighting are being solved by the use of high strength steel, aluminum, magnesium and other non-traditional materials such as carbon fiber reinforced plastic (CFRP). Working in parallel, new material joining products and systems must be developed to enable the use of these materials in vehicles. Sika has been the innovation partner for automotive OEMs in developing these solutions for car body engineering, including SikaPower® and Sikaflex® adhesive products and SikaReinforcer® structural inserts.
Sika will be featuring its latest innovations in car body lightweighting. Highlights include Sikaflex®- Ultra High Modulus one-component PUR for structural and crash resistant bonding of mixed material, in particular for bonding CFRP to aluminum in non-conventional body shop; as well as Sikaflex®- Ultra Low Modulus one-component PUR for roof panel stiffening and damping. The presentation will also provide an overview of the success behind the current VW e-Golf where Sika’s High Strength Bonding solution, using SikaPower® adhesive and SikaReinforcer® structural inserts, was engineered and implemented to enable a weight saving of more than 2.5 kg per vehicle while still fulfilling the most demanding crash requirements.
For corrosion protection and forming ease automotive steel sheets are commonly oiled. Structural adhesives, especially epoxy based, are capable of absorbing the oil to some extent during curing. No systematic research has been performed to assess the effect of remaining corrosion protection oil on structural properties of adhesives and joints.
Hence, in this work the influence of different amounts of corrosion protection oil on the bulk properties of an adhesive and the bonding properties of steel joints is investigated. Therefore, a model adhesive, strongly related to a commercial automotive type, is used and a commercial corrosion protection oil. The used substrates are hot-dip galvanized zinc (GI) and zinc-aluminum-magnesium (ZM) coated steel sheets supplied by voestalpine Stahl. The oil is either applied on the substrate surface or admixed to the adhesive. The influence of oil on the thermo-mechanical properties of the adhesive, prepared as bonded joint, in case of the applied oil on the substrate, and bulk material, in case of admixed oil, is characterized using Dynamic Mechanical Analysis (DMA). Bonding strength is examined via tensile lap shear tests with additional fracture pattern evaluation. Additionally, the effect of oil on the curing properties of the adhesive is analyzed with Differential Scanning Calorimetry (DSC).
Regarding the curing behavior a shift of the exothermic peak to higher temperatures with growing amount of admixed oil was ascertained. Furthermore, the glass transition temperature was slightly reduced indicating a plasticisation effect.
Under confined conditions, shrinkage may influence the formation of interphases in adhesively bonded joints and negatively impair their strength and durability. Therefore mastering the curing kinetics and the physicochemical changes in the transition from the liquid to the solid state seems essential to successfully process adhesives in demanding applications.
The local mechanical properties of interphases adjacent to the surface of adherents have a strong impact on the performance and durability of structural adhesive joints under detrimental service conditions. In this presentation, a methodology for gaining insight into the local mechanical properties of polymer interphases in structural adhesive joints made with ambient temperature curing epoxy adhesive will be presented. Localized stress-strain-properties in the cross-section of shear-loaded adhesive joints will be related to thermal and mechanical curing conditions.
The authors kindly acknowledge funding by the German Research Foundation DFG in the framework of their 4th young academics academy “Material Science and Material Engineering” with grants from the Federal Ministry of Education and Research (BMBF).
Adhesive; Epoxy; Interphase; Shrinkage; Gelation; Stress-Strain-Analysis
The trend in the area of electrical and electronic devices is leading to a significant increase in miniaturization and to an increase in the performance output. The arrangement of the components in electrical circuits is further compressed. These development trends inevitably lead to increased heat generation and heat spots. In order to maintain or even optimize the performance of the components, efficient heat management is becoming increasingly important. The optimized and efficient heat dissipation is one of the most important requirements for the new development of electrical and electronic devices.
With heat conductive adhesives as a thermal interface, the thermal stress can be reduced in the case of bonding and, moreover, a permanent mechanical fixing can be realized. Thus, the use of thermally conductive adhesives provides a number of important advantages.
Thermosets are widely used in E & E applications, but metals are still the most important materials in heat management. When used in conjunction with electrical components with high energy densities (processors, light-emitting diodes, electric motors, batteries, electronics, etc.), new requirements for efficient heat dissipation with simultaneous electrical insulation performance are required. Metallic fillers achieve a high thermal conductivity, but at the same time the adhesive becomes electrically conductive. This is not constructive for many E & E applications. Through the use of both ceramic and mineral fillers, an electrical insulation can be achieved parallel to the improvement of the thermal conductivity.
The talk should present how to increase effectively the thermal conductivity of adhesives with mineral fillers with simultaneous electrical insulation properties by using the example of 2K epoxy glue. The presentation will include basic information concerning thermal conductivity, investigation results and application examples as well.
Batteries represent the most promising electrical energy storage system for many applications. Especially lithium ion batteries grow in their importance for the portable devices and electric mobility field. The individual constituent parts in such batteries are graphite as anode and lithium metal oxide as cathode material. In addition, carbon black and the binder consisting of polyvinylidene fluoride (PVdF) are added. This polymer is quite expensive and needs to be solved in N-methyl-2-pyrrolidone (NMP), a toxic solvent. This requires numerous expensive efforts for safety regulations.
In order to improve the carbon footprint and reduce the harmful ingredients, an epoxy-based binder system based on renewable raw materials will be developed for the application in lithium ion batteries. The properties this binder have to provide are a good adhesion to ensure the contact between electrode material and collector foil, interaction with the electrolyte for ionic conductivity and compatibility with the active materials for electric conductivity.
The starting materials of this investigation are two component adhesive binders of modified conventional epoxides and epoxidized plant oils which were tested with hardeners like fatty amines and anhydrides. The bio-content varies from 20 up to 100%.
Furthermore, the new epoxy resins are evaluated in terms of mechanical strength and flexibility, compatibility with the electrolyte solution, processibility and adhesion strength for applications in lithium ion batteries.
A bio-based route to the production of trans-β-farnesene has recently been commercialized. Trans-β-farnesene is capable of being polymerized by both anionic and cationic pathways, creating low molecular weight polymers with structure-property relationships unique within the diene class of monomers.
Trans-β-farnesene is produced through fermentation of sugar feedstocks. The pathway offers an alternative to petroleum-based feedstocks derived as by-products of naptha or ethane cracking. Anionic polymerization of the monomer produces a highly branched "bottle-brush" structure, with rheological properties that are markedly different from those of linear diene polymers. Specifically, a lack of entanglements is observed even at relatively high molar masses. For dihydroxyl-terminated oligomers, Tg as a function of molar mass follows a trend opposite non-functional materials.
Trans-β-farnesene is cationically polymerizable and enables to produce a new generation of tackifiying resins, having unique properties.
The synthesis and characterization of trans-β-farnesene-based polymers will be presented. Their main properties will be also reviewed in order to demonstrate their applications in Adhesive Industry.
NX-2026™(3-pentadeca-dienyl-phenol) is a very high purity cardanol derived from the bio-oil Cashew Nutshell Liquid. In a previous paper, this substance has demonstrated various benefits including favorable deblocking conditions, lower viscosity, and excellent storage stability in comparison to commonly used phenolic compounds. One of the most known deblocking methods involves the exposure to elevated temperatures: for example, 3-pentadeca-dienyl-phenol blocked MDI can be deblocked at temperature close to 150°C. However, not all the substrates (e.g. plastics) and applications can tolerate such high temperatures for deblocking; therefore, the possibility to tune the deblocking conditions can be a valuable tool to further highlight the applicability of 3-pentadeca-dienyl-phenol as a versatile alternative to traditional prepolymers’ blocking agents.
In this study, Cardolite will present different approaches to control deblocking conditions. Firstly, 3-pentadeca-dienyl-phenol blocked prepolymers based on aromatic (MDI, TDI) and aliphatic (HDI, IPDI) isocyanates are prepared, characterized for their deblocking temperatures and used as model substrates for the study. Key factors for controlling deblocking conditions including catalysts, deblocking agents (amines, polyols), and solvents will be investigated.
Birch tar was used widely as an adhesive as early as the Middle Paleolithic to early Mesolithic era. Neanderthals produced tar through the dry distillation of birch bark as early as 200,000 years ago.
Ends of fletching of arrows were fastened with birch-tar and birch-tar-and-rawhide lashings were used to fix the blade of axes in the Mesolithic period. In cooperation with The Centre for Baltic and Scandinavian Archaeology (Zentrum für Baltische und Skandinavische Archäologie – ZBSA) that operates as non-university research institute with an international orientation under the aegis of the Stiftung Schleswig-Holsteinische Landesmuseen Schloss Gottorf (Foundation of the Schleswig-Holstein State Museums at Schloss Gottorf), Jowat has tested birch tar samples that were made at ancient conditions. Tests included modern techniques such as DMA, TGA, DSC and FTIR, as well as tensile testing of glued samples. During testing even true replica of projectile foreshafts made of reindeer antler were equipped with Hamburgian lithic shouldered points and hurled on an organic target (deer) employing different mounting techniques (e.g. birch tar adhesives) and acceleration media. The goal was on the one hand to learn something about the performance of this ancient glue compared to modern adhesives and on the other hand to identify whether archaeological finds were parts of ancient projectiles.
Biological adhesives are produced by many organisms, ranging from bacteria and fungi to much larger animals and plants for a variety of purposes as construction, predation, defence, locomotion and attachment, just to mention some. Moreover many of these secretions have advantages over synthetic counterparts in terms of biocompatibility, long term stability, application range and mechanical properties.
Knowledge of its composition, structural design and interactions with surfaces would be helpful not only to understand biological adhesives but also to mimic these properties for artificial applications.
The COST Action “European Bioadhesives Network” aims to unite the widespread European expertise in the field of biological adhesives (spanning biology, physics, chemistry, and engineering) by streamlining and pooling knowledge, methods and techniques. We aim to understand the fundamentals of natural bonding principles and test these natural systems in vivo and in vitro, paving the way for future technical applications. Beside the European academia and industrial community we also aim to raise public awareness of the diversity of bioadhesives and necessity to characterize and evaluate these secretions.
Regenerative medicine urgently needs biocompatible adhesives suitable for therapeutic use in the treatment of small bone fractures. Such an adhesive should allow rapid bonding of the bone fragments without the need for the attachment of plates and screws. The use of biological glue from marine mussels, so-called mussel-adhesive proteins (MAPs) - as potential environmentally-friendly bio-inspired adhesives - could be a solution to this problem. In nature, mussel secrets adhesive proteins and efficiently adheres to stone and other inorganic surfaces and even to man-made products such as metal and plastic (e.g. Teflon) materials. The secret of these bio-glues is the presence of catechol groups in the side chain of the non-proteinogenic amino acid L-dopa which is produced post-translationally by tyrosine hydroxylation and is capable of surface adhesion.
So far, adhesives have been established in clinical practice mainly in the field of skin closure and as hemostyptics. The advantages of adhesives also make them interesting for the adhesion of the mucous membrane, musculature, and parenchymatous organs. Soft tissue adhesives are of particular interest when fixation of tissue by suture is not applicable, e.g., in case of surgery areas of limited accessibility (middle ear, endonasal, pharynx/larynx/trachea) or when endoscopic and minimally-invasive techniques are employed. An adhesive bonding with subsequent fixation by scar tissue could be a significant improvement of the surgery results and wound healing. The preconditions for the use of adhesives in soft tissues are biocompatibility and biodegradation of both the adhesive itself and its degradation products. The glue has to develop a sufficient adhesive force under moist conditions, allowing an immediate functional use of stress-bearing implant beds.
In collaboration with our project partners, we developed innovative and biocompatible soft tissue glues for application in the wet milieu of the inner body surfaces (mucosa, muscles, conjunctive tissue, and endothelium). The aim of our experimental investigations was to examine the developed adhesive systems with regard to their suitability for mucosal adhesion with the associated special requirements, and to evaluate physical and biological properties in vitro and in vivo.
In a self-developed in vitro test setting, suitable adhesive systems for the use in soft tissue were evaluated.
Additionally, cell culture investigations were performed using NIH3T3 cell line and MC3T3-E1 cell line. The vitality of cultured cells which were treated with extracts of the developed adhesives was determined with a viability assay.
Furthermore, using an in vivo cartilage mucosa model on New Zealand White Rabbits the use of the selected adhesives in a typical surgical field was tested. The following parameters could be evaluated in a standardized manner using this animal model: bonding in a moist environment, fixation of tissue (mucosa on cartilage), and applicability via minimally-invasive surgical instruments. A histomorphometric module for distance measurements was developed for the standardized evaluation of histological specimens. Thus, in addition to the light microscopic evaluation, a good histological comparison of the different adhesives was possible.
The in vitro tests revealed that the polyester urethane based adhesive system is well suited for the adhesion of soft tissue in a moist environment. The six most suited adhesives showed a medium to strong adhesive power both in the wet bonding of test specimens and in the bonding of porcine mucosa and musculature. The moist ambient environment could be simulated very well with the in vitro test and it was possible to evaluate application-oriented methods. Also, the cell culture investigations indicated a positive influence of the new adhesives on the viability of cultured cells.
This test procedure enabled the evaluation of various one- and two-component adhesive systems with physically or chemically induced polymerization. Due to the intensive in vitro testing, the number of suitable adhesives for animal experiments could be narrowed down considerably.
The short-time animal experiment demonstrated the suitability of two particular polyester urethane adhesives with very good biocompatibility and adhesive properties. The two selected adhesives were evaluated with very good results in terms of biocompatibility, absorption and application properties in the long-term animal trial. Both adhesives are polyester urethanes with terminal isocyanate groups in combination with polyoxyethyleneamine as activator.
Pressure-sensitive adhesives based on silicone materials have emerging potential as adhesives in healthcare products, in particular for gentle skin adhesion.
Two challenging problems have been addressed 1.) the development of thin, self-adhesive films for reversible attachment to fragile structures like the tympanic membrane and 2.) the investigation of complex mechanical interaction of soft elastomers with surfaces possessing high surface roughness, like skin. Here, we characterized in detail the adhesion properties of composite films possessing a thickness between 50 µm and 350 µm. Self-adhesive thin films composed of two different polydimethylsiloxane elastomers have been developed for the treatment of tympanic membrane perforations. The adhesion characteristics of the elastomers have been studied in response to film thickness and roughness by normal adhesion measurement and peel-tests. In order to influence cellular migration and proliferation, the effect of passive protein adsorption onto adhesion mechanics and biocompatibility has been analyzed.
Taken together, reversible attachment of the patches to the tympanic membrane of mice exhibiting an experimentally induced tympanic membrane perforation has been achieved.
The use of adhesive tapes in medical devices are becoming ever more popular, not only because of their primary functions such as fixing dressings, protecting wounds and securing devices in place but also because when used in combination with other materials they can support the healing processes, allow gentle removal, improve moisture management, enhance patient comfort and extend device wear times.
When designing medical adhesive tapes many questions arise which to answer demands a profound knowledge of how skin functions while also understanding how adhesion science can be used to overcome skin-bonding challenges.
Medical practitioners, adhesive developers and tape engineers have focused their attention on advanced materials that are able to fulfill the highly demanding applications where direct contact to skin plays a crucial role, such as wound care dressings, surgical drapes, transdermal drug delivery devices and diagnostic sensors. Only by selecting the correct combination of components will the product be optimized to meet the design needs of the medical device while keeping skin safe.
On the other side, testing the performance of medical tapes is one of the major challenges constantly faced by the adhesive industry. For this purpose Lohmann presents the “Smart bonding approach” focused on designing adhesive properties, matching advanced materials for technical requirements and skin safety and developing customized characterization methods mimicking skin and application conditions.
At Lohmann, as the Bonding Engineers, we transfer our expertise with raw materials, state-of-the-art technologies and specific testing capabilities to adapt the design to deliver the best performance-based product. We remain a constant and reliable partner during the whole process.
LOCTITE® Medical Devices Adhesives have been specified by Medical Device Manufacturers all over the world for decades, based on their overall portfolio of advantages, e.g. use on a wide range of materials and various geometries, allowing new design options and implementation of new materials. Any medical device application relates directly to biocompatibility, e.g. according to ISO 10993, which is certified on the polymerized adhesives, and confirmed in thousands of various medical devices by their market approvals.
The range of applications includes the whole spectra of medical devices, from diagnostic to operational instruments, from blood collection to drug delivery system or from disposable to non-disposable devices. In depth experience on adhesive dispensing and curing, part handling and preparation as well as quality inspection led to well-designed manufacturing processes, from manual operated workstations to high-output integrated automatic manufacturing lines.
Developments by Henkel in Medical Device Adhesives serve on one side the market trends, on the other side widens the use case of adhesives, by implementing new features into existing technologies as well as by combining two adhesive technologies into one product. Examples of new adhesives developments will be shared.
For fast productions in high numbers and specifically for miniaturization more and more light curing adhesives are used, due to their extremely fast curing in sometimes less then 1s. In the last years the technology of the curing lamps for such systems changed from bulb-lamps which had short life times and a big loss of intensity during life time to LED-lamps which show a lot of advantages. For example the efficiency is much higher due to the fact that the complete wavelength spectrum of a lamp is used to start the photo-initiator.
With optimized high power LED’s now a new lamp generation is possible. It performs intensities of up to 2W/cm² in area lamps with lifetimes around 10-20 times longer than bulb lamps. With the new integrated touch technology, it is very easy and comfortable to control intensities and times.
Aqueous Polyurethan dispersions based on semi-crystalline polyurethane (PU) polymers have long demonstrated their outstanding performance and are a well-established bonding technology in several demanding industrial applications. Due to their thermal activation properties and sharp melting area, these adhesives allow for efficient bonding processes with short bond strength build-up times.
To achieve highly durable bonds the semi-crystalline PU adhesives are either processed as 2-component adhesive using isocyanate crosslinkers or as 1-component adhesive dispersion containing surface deactivated solid isocyanate particles (so-called latently-reactive adhesive dispersions).
Such latently reactive adhesive dispersions are storage stable at ambient temperature, but can activated at approx. 70 – 100°C to initiate crosslinking. They can either be preapplied onto a substrate or decor film or, alternatively, used to produce a free adhesive film.
Latently reactive adhesive films are gaining increasing interest in industrial adhesive markets, because the use of films allows to avoid handling of liquid adhesive for adhesive users, and to separate adhesive application from bonding process in time and location. In addition, these PU adhesive films show excellent adhesion to several materials including and not limited to: leather, wood, paper, aluminum, steel and many plastics (PVC, PC, PA; ABS, etc.). With this new adhesive technology new applications for semi-crystalline PU adhesives could be developed.
Kaneka’s MS Polymer has proven its quality and versatile application area over more than 20years in the adhesive & sealant market. However to use it as the backbone polymer in psa-formulations its moisture curing step requires specific adaptations compared to a ‘normal’ psa-coating process (solvent, hotmelt or UV curable).
But using them as additive is pretty straightforward and adaptive in traditional psa formulations (cf. acrylics, rubber,hotmelt,..). Thanks to the wide range of MS PolymerTM types going from low to relative high Mw, various levels of functionality and branching one can move properties in different directions depending on the selected type (or combinations).
Initial studies have been done on an acrylic psa-adhesive modified with various MS Polymer grades in different concentrations to quantify the performance shift and highlight the possibilities of MS PolymerTM.
Since their commercial introduction in the 1960s, silicone PSAs have found uses in a variety of applications. Some of the long-established applications for silicone PSAs are found in industrial operations (masking, splicing, roller wrapping) as well as in electrical and electronics, medical care and healthcare, and automotive sectors. Since 2000, there has been much interest in new uses of silicone PSAs, especially in applications such as medical and industrial tapes. Silicone pressure sensitive adhesives (PSAs) have stability and flexibility that is unmatched by organic PSAs.
They have been used for many years in areas where typical organic PSAs have failed. One of the most important uses is in applications where large temperature extremes occur. Driven by needs for regulatory compliance and changing performance requirements, silicone PSAs based on new silicone chemistry and cure mechanisms have also emerged. Yet, facing the total PSA-market silicone PSAs still have an exotic touch. In this paper the history and chemistry is described which is behind that unique class of PSA.