Fifteenth annual meeting of the adhesion society

Intabond 92: Fifth International Conference on Speciality Adhesives for Laminating and Coating Penta Hotel, Heathrow, London, UK, 1 5-16 June 1 992

Mr Derek Miles and his colleagues at Dermd Research Ltd are to be congratulated on running a two-day conference of high quality on their rather spectalized aspect of adhesives in the present t~mes when one hears of so many meetings which are having to be cancelled Just on 80 people met at the Penta Hotel for the two days of th~s event In the hght of all the varied pressures - - legal and social - - for enwronmentally favourable processes, users of adheswes have little optmn but to seek to change from solvent-based products and hazardous processes such as flame lamination. Th~s concern for 'greener" methods of producing the various products formed the main focus for this meetmg The opening paper by K.W. Allen of The City University, London reviewed some of the more fundamental aspects of laminating for textdes This was followed by F.A Goosens of Stork Brabant BV, The Netherlands, who considered some of the problems of control in these processes. Then A.S. Masters of 3M (UK) spoke on the apphcations of hotmelt adhesives m the shoe industry After lunch, F A Woodruff of WEB Processing Ltd rewewed some of the specific problems of flame laminating and the ' alternatwe techniques which can replace th~s, parUcularly emphastzing the sigmficance of thermoplastic powder methods Derek Miles followed, in his m~mitable style, talking about the selection of appropriate types of adhesive for laminating and coating. This led on to a discussion of the techmques for pattern coating of hot-melt adhesives by G Taverner of Mercer Hot Melt Systems. C.M. Klatte of Machtex, The Netherlands, then gave a significant paper on the rapid development of polyurethane adheswes to meet contemporary demands Next there was one of the more 'scarey' papers, at least from the viewpoint of a thoroughly old-fashioned chemist, discussing the effects of the Control of Substances Hazardous to Health (COSHH) Regulations in the

adhesives industry and given by J Delaine, a consultant in this field. The first day closed with a paper on repulpable hot-melt adhestves for the paper and board industnes, by H D a h m a n e of Datec Adhesives Ltd. H Scholten of Huls AG, G e r m a n y opened the second day wath a paper on acceptable techmques for laminating textdes in motor cars, and he was followed by Derek Mdes discussing some newer techmques used m thts same field here in the UK. Then P.T Judd of Dritex International Ltd spoke on heat seal powder adhesives of high performance, and B J. Sikkel of 3M (UK) discussed the parttcular use of film forms of thermoplastic adhesives G. McCutcheon of Cremer and Warner Ltd followed with a consideration of the toxic aspects of fumes from heat lamination and thetr consequences - - another area of frightemng ~mplications, at least for the costs involved The second afternoon began with a presentatton by P Godfrey of Caswell & Co Ltd on the development of some novel water-based laminating adheswes Then R Conway from WEB Processing Ltd spoke about the efficient removal by incineration of solvent vapours after textde coating, and all its advantages C_ Jarrell of the Nordson Corporation, USA. spoke about contemporary technology for the apphcauon of hot-melt materials to fabnc A Wildey of Orr & Boss Consultants gave a very dluminatmg paper on the true nature of waste and methods for tts reduction to a m i m m u m Finally N.J Rowbottom spoke on the techniques of cryogemc g n n d m g and its particular advantages for commlnutlon of thermoplastic adhesive materials Overall this was a very useful and interesting conference wath some very worthwhde presentations 1 look forward to the sixth m the series

I< W. Allen Adhesion Science Group, City Universtty London, UK

Fifteenth Annual Meeting of the Adhesion Society Hdton Head, SC, USA, 16-19 February 1992

With 180 participants and 75 presentations, this meeting, led by C h a i r m a n Jim Boerio, was the largest so far in the annual meetings of the Adhesion Society and second only to the International Adhesion Society meeting in Wilhamsburg in 1987. The Society presented an award for 'Excellence in Adhesion

Science" to Professor AJ. Kinloch (of Imperial College, UK) for his work on fracture mechanics applied to adhesion, of which he gave some examples. Presentations covered all fields of adhesion and the average standard of the papers was fairly good. The fact that adhesion science is so close to adhesion

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practice means that many works are essentially devoted to applied science - - under contract. Most workers don't have the time (or money) to address the fundamental questions that their work raises One thanked his sponsor, saying, ' . if he knew what I did with his money)' A. Gent (University of Akron, USA) showed that our current understanding of the relationship between fracture energy and adhesion does not account for the high dissipation factor measured at low speed. Similarly, H.P. Schreiber (Polytechmc Institute of Montreal, Canada) presented results obtained upon measuring solvent-polymer interactions and showed that, despite Its previous success, the acid-base theor2,' could not explain his results Meaningful testing remains a problem at high adherence levels (and physicists are cautious about testing equations on low adherence systems) D. Dillard showed that the peel tesL the blister test and its variants apply for fracture energies up to 200 J m -, above this value only the double cantilever beam (DCB) test gives sensible results as in wedge testing The speaker also showed how a flat DCa specimen could be loaded at constant energy release rate Too many researchers use pull or lap shear testing to characterize lnterfacial modificatmns when it is known that these tests are very insensitive to interfacml changes. This point was exemplified by G.L. Anderson who showed that the DCB configuratmn revealed a strength reduction of some adhesives in the presence of oily surfaces that was not detected by shear testing. This has obvious practical consequences It was also shown that some adhesives are able to displace the oily contamination as well as do silanes The effect of surface treatment deserves careful study and meaningful testing. Treating styrenebutadiene rubber with trichlorocyanuric acid gives good results, but only for short treatment times; too long a treatment produces weak boundary layers which decrease adhesion (J.M Fernandez, University of Alicante, Spain). Analysis proved that plasma treatment of LARC-TPI results in the formation of a low molecular weight overlayer which reduces adhesion (J.W. Chin, Virginia Polytechnic Institute, USA) Functional groups on polymer surfaces may undergo chemical reactions which allow the surface properties to be controlled. The fluorine on fluoropolymer surfaces may be transformed into carboxylic groups. giving rise to classical reactions and changing surface properties (T.J. McCarthy, Umversity of Massachusetts, USA).

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With the development of surface analy-hcal tools more and more information has become available on the compositmn of surfaces and interphases' however, the mterpretatmn of such data ~s not always simple. The presence of alummium on the adhesive side of a fractured aluminium-bonded joint does not always mean that fracture occurred in superficial alumina layers When an adhesive comes into contact with a sohd, complex chemical modifications occur Metals can dissolve in adhesives and lead to erroneous conclusions For example, Versamid epoxy adhesive produces alumimum carboxylates at the alummium side of the interface which could be responsible for the adhesion (N G Cave, Umversity of Cincinnati, USA), Hardener segregation at the surface is also often observed. Some laboratories are equipped wath scanning tunnelling or atomic force microscopes which give astounding information about the state of the surface. When a student, I thought atoms were impossible to observe! Now surfaces are seen at the AngstrOm level. R.C White (Columbia Umverslty) described a polylm~de surface while P. Chartier (St Gobain Recherche Center, France) described the surface of glass after debonding of a polyurethane hot melt Instead of spending t~me doing experiments, J.F, Maguire (Southwest Research Institute, USA) prefers to simulate the interactions of a polymer chain with a solid surface on his computer. We were able to watch on screen how the polymer chum adsorbs and folds over an ideal surface to ensure its minimum energy, New reactive monomers have led to new adhesives and elastomers such as bipropynones (F W. Harris, University of Akron, USA) and also to new thermoplastics such as benzocyclobutene (K_J. Bruza. Dow Chemical, USA), There are many fields where adhesion applies, the most spectacular probably being medicine. B.J. Love et al_ (Georgia Institute of Technology, USA) showed how to modify adhesives for dental restoration and Katz (Israel Institute of Technology) presented photographs o f bone cicatrization through use of polyurethane adhesives to consolidate a fractured bone As Is usually the case with such large meetings, all the presentatmns cannot be summarized; the above is an overview of those communications which struck this reviewer the most

J. Cognard Asulab SA, SMH Group Neuch~tel, Switzerland