Session 20: Adhesives & Sealants III
Chair: Stephan Hinterwaldner, Hinterwaldner Consulting, DEThe third adhesives session is dedicated to new innovations on curing and novel concepts from natural origin, either principles mimicking nature or raw materials from natural resources such as biobased resins. Additionally novelties such as the use of photolalent bases to improve control over the curing process and the development of new additive technologies are discussed as well as the investigation of the curing behaviour of reactive resins.
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Wednesday Morning 9.00 – 12.30h
Room Istanbul
20.1 9.00 – 9.30 h Inductive hotmelt adhesives curing – a new approach Prof. Christian Lammel, IFF, DE Modern serial processes have cycle times within seconds or few minutes. Unfortunately most polymers have a curing time of minutes, hours or even days. For this reason, it is very important to accelerate cross-linking reactions by increasing the temperature. IFF GmbH develops and distributes special induction heating equipment, which is exactly designed for these purposes: The inductive heating of the parts or special fillers (nanoferrites) is used for getting initial strength within seconds to make a further processing possible. This contact-free heating technology has the best efficiency which reduces energy consumption and costs. Furthermore a new bonding technology with a pre-applicable adhesive has been developed, which reduces the bonding process to a heating process and leads to safe and reproducible bonded joints without any previous knowledge needed. It is possible to do the structural bonding of fasteners within seconds.  | ||
| 20.2 9.30 – 10.00 h Cure monitoring of reactive adhesives Stephan Knappe, NETZSCH Gerätebau, DE For the investigation of the curing behavior of reactive resins, Dielectric Analysis (DEA) in accordance with ASTM E 2038 or E 2039 has stood the test of time. For measurements of the ion conductivity, which is calculated from the dielectric loss factor, or its reciprocal value, the so-called ion viscosity, single- and multiple-channel equipments with different sensor types are available. The great advantage of DEA is that it can be employed not only on a laboratory scale, but also in process. The paper presents the DEA technique and various applications examples for the curing of reactive adhesives. | ||
| 20.3 10.00 – 10.30 h Lessons from nature – Nanotbionics for novel adhesives Dr. Marius Kölbel, MaterialInnovation, DE Nanotechnology and bionics could be the next trend in adhesion. Inspiration comes from nature. The sticking mechanisms of geckos, insects, spiders and climbing plants are based on nanoscale effects. Now that their functional principles are well understood, the road to their technical use is paved. Combinations of different natural principle broaden the scope of potential applications. Novel adhesives for industry, surgery, dental repair and climbing robots come into reach. The main challenges are regeneration and reversibility. For the latter there is an approach nature does not know: magnetic nanoparticles. This contribution will give an overview of recent discoveries and innovations from research institutes and R&D departments the world over. 10.30 – 11.00 h Networking: Refreshments & Coffee Break | ||
| 20.4 11.00 – 11.30 h Novel biobased thermosetting resin Prof. Jukka Seppälä, Helsinki University of Technology, FI There is an increasing need and interest to develop feasible alternatives for petroleum based polymers and resins. From environmental perspective, it would be important to overcome the problems due to the plastic wastes and reduce the use of fossil fuels. Here we introduce thermosetting resin that is substantially based on green renewable feed stock materials. Lactic acid is a bio-based monomer produced in large quantities and polymerized to high molecular weight thermoplastics through ring opening polymerization of lactides. The direct polycondensation of lactic acid leads to oligomers with molecular weights up to 10 000g/mol . These oligomers are lack the mechanical properties needed for typical polymer applications. We have developed biobased resin by which aliphatic hydroxyl acids, such as lactic acid, can be polymerized into poly(lactic acid) by direct polycondensation with a use of suitable catalyst. Our technology produces low-melting, easily processable thermoset oligomers which are made from hydroxy acids and polyol monomers, end-group modifiers, components bringing unsaturated site to end-groups and possibly components to modify properties such as hydrophobicity or elasticity. The molecular architecture, branching, molecular weight and different monomer units can be varied to produce different lactic acid based precursors. Resins are cured by free radicals to produce mechanically excellent polymers with properties from elastic to rigid, touch materials. Crosslinking of the resin to a high molar mass crosslinked polymer takes place by heat, radical producing compounds, UV or VIS light or other radical exposure. Crosslinkable poly(lactic acids) are suitable as coating materials to produce water, moisture and grease barrier on e.g. paperboard. In addition, they can be used as thermoset binders in filled, fibrous or laminated structures. Biobased thermosets can be processed by a wide variety of processing methods, such as spray lay up lamination, resin transfer moulding (RTM), resin film infusion (RFI), compression moulding (CM) and sheet moulding compounding (SMC). Totally or substantially biobased composite applications can be designed by combining biopolymers with natural biofibres such as cellulose, cotton, hemp, jute, flax. Some of these will be reported in this presentation. | ||
| 20.5 11.30 – 12.00 h Influence of radiofrequency bonding procedures on the performance of PVAs dispersion adhesives Dr. Fabio Chiozza, Vinavil, IT The radiofrequency generators are used in the wood industry sector for drying the adhesives because they allow a reduction in the production time while maintaining unchanged the performance of the bond-line. The primary effect of electromagnetic fields is the dissipation of the energy in form of heat, thus allowing the rapid desiccation and, for appropriate products, the promotion of eventual cross-linking. However little is known on the effects related to some operating conditions, such as quantity of glue, exposure time and frequency of the generator. Moreover, the type of adhesive used is generally not taken into account. The performances of three PVAc dispersions applied with various bonding procedures (such as pressing time, adhesive spreading, bonding pressure etc.) and spread on two different wood species were tested according to the most relevant reference standards (EN204-205, EN-14256-14257, ISO 6238) and were analysed in order to select the procedure giving the maximum efficiency to the process. | ||
| 20.6 12.00 – 12.30 h New opportunities in adhesives using photolatent bases technology Benno Blickenstorfer, Ciba, CH The cross-linking of suitable formulations by base-catalyzed polymerization and polycondensation reactions is well known for use in conventional coating applications and is highly attractive for certain applications. Furthermore, latent base catalysts are an attractive possibility to improve control over the curing process of such formulations while maintaining cure speed and the excellent properties of the cured article. The use of light as the trigger is very attractive in order to achieve optimum control over the curing process. Transferring the experiences from coatings, this paper will report on the design and the application of photolatent bases into adhesives formulations, as this technology is able to offer considerable economic and ecological advantages. It will show that this new class of catalyst considerably expands the scope of the UV technology into new formulations, thus providing the end user with the advantage of full control of the curing process, while producing adhesives of outstanding performance. | ||
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