y z z z z z i
Figure 6 3D laminating of PVC film onto 3D panels made of MDF . This is a heat laminating on a vacuum press courtesy of Burkle Germany . 1 PVC film 2 laying pallet 3 supports for the panels 4 3D MDF boards 5 heating plates 6 top sealing frame 7 preheating pressure 8 pressure chamber 8.1 vacuum Chapter 5 Thermosetting formaldehyde based adhesives, by Dr A. Pizzi, a detailed study of UF, PF, RF and MF adhesives and glues, their chemistry and their uses in woodworking, panels and furniture this...
The Volkersen View
The overlap joint was first analysed by Volkersen in 1938 and he concluded that the maximum concentration of shear stress in an adhesive at the ends of an overlap nc max was where A is a dimensionless coefficient and W is a function of the moduli and adherend thickness. If both the adherends are the same size and the same material, then W 2 and the equation becomes The maximum shear stress is therefore dependent on the dimensionless coefficient A, which can be calculated using the following...
List of Suppliers for UV Curing Techniques Adhesives and UV Equipment
photoinitiators, acrylate monomers, oligomers EDD K-H201, D-67056 Ludwigshafen, Germany. BASF Corporation, USA, 3000 Continental Drive N. Mt. Olive, NJ 07828, Tel. 973 426-4575, Fax 973 426-4676 ww.basf-corp.com Products N-vinyl caprolactam, N-vinyl formamide, vinyl ethers, tert-butyle acrylate, butanediomonoacrylate, tertiary butyl methacrylate BASF Corporation Performance Chemicals for Coatings 4330 Chesapeake Drive, Charlotte, NC 28216, USA, Tel. 704 735-1242, Fax 704 398-4353 Web...
Release Coatings
The PSA covered substrates used by the tag and label industry need to be protected during storage by a film which should be easily removed just before use, without loss of shear strength. Such release coatings consist usually of a plastic film or a paper coated with a uniform and thin film of a reactive silicone which is cross-linked via chemical processes promoted by heat or UV-radiation 124,125 . Silicones are known to lack adhesion to most substrates because of their low surface energy, a...
Wa [ydyd yd ydypyp yf YP
It has been noted earlier that Chin, McCullough and Wu 57 measured contact angles for water and diiodomethane on surfaces of silicon, silicon which had been fluorinated with Cl3Si CH2 2 CF2 7CF3, and polydimethylsiloxane, and calculated surface energy components using both geometric and harmonic means. They also calculated work of adhesion by both methods, and also measured it directly using Figure 18 Dependence of work of adhesion upon the surface tension of the aqueous phase, for a range of...
Knife and Doctor Blade Coating
Figs. 38 and 39 show these equipments. The adhesive forms a thick fillet behind the adjustable knife. There are three systems refer to Figs 38-41 - knife over roll coater Fig. 38 , - floating knife where the coating blade rests on the web away from the roll, - doctor blade where the knife is replaced by a rounded doctor blade for a smoother application Fig. 40 . Usually, adjustable springs press the knife or doctor blade against the web. There are several possible shapes for the knife Fig. 41...
WaterSwelling Sealants
Among the wide range of Sika's construction sealants, the water-swelling sealant, SikaSwell , shows some construction features and is described here. In the construction area, optimal sealing is often required between hardened and fresh concrete, between two pre-cast concrete elements, etc. The special formulated moisture-reactive sealant offers a watertight construction joint in such applications. In contact with water, the sealant swells within 7 days to more than 100 of its original volume...
Structural Adhesives
A considerable amount of work has been devoted to the bonding of two elements by means of UV-curable structural adhesives 78-92 . The two parts of the assembly can be identical homolaminates or of a different nature heterolaminates , and consist either of flexible films like polyesters, poly vinyl acetate , nylon, aluminium foils and paper, or rigid transparent plates like poly methylmethacry-late , polycarbonates, poly vinylchloride and mineral glass. Obviously, one of the two parts must be...
Sikas PURHybrid Products
In the following section, representative PUR-Hybrid products are described for the construction and industry market segments 6.8.3.1. PUR-Hybrid Systems for Construction For indoor or outdoor joints subject to high movement, sealing can be done with the universal construction sealant Sikaflex -20 AT. Such joints fulfill the rigorous DIN 18540 ISO 11600, F25LM standard Fig. 81 . SikaBond -66 AT is a universal assembly adhesive for construction as it is a phthalate-free PUR-Hybrid adhesive with...
Different Adhesion Models
There currently exists no uniquely valid model of adhesion but rather a series of different models each having its own field of application. The chemists' task is to combine Note of the editor For more information about theory of adhesion the reader should refer to the chapter 1 Theory of adhesion by John Comyn, in this volume. all the different models and evaluate their individual importance from case to case. In order to achieve this, there must be sufficient information about the materials...
Condensation Prepolymers Polyimides
Historically, the adhesives based on reactive condensation prepolymers were the first materials to be extensively studied, developed and introduced to the market. One of the best performing polyimide in this category is Nolimid 380 produced by Rh ne-Poulenc after an extensive series of tests 82 . The resin binder is the mixture of monomers 30a and 30b, as well as the low molecular weight polyimide 31 of Fig. 15. Typical compositions are prepared as previously reported by mixing the two monomers...
Linear Polymer Precursors
The method used to prepare aromatic polyimides is illustrated in Fig. 8 with the reaction of 1,2,4,5-benzenetetracarboxylic acid dianhydride pyromellitic acid dianhydride, PMDA 1 and 4,4'-oxybisbenzeneamine oxydianiline, ODA 2 5 . After a charge transfer complex between compounds 1 and 2 is initially formed, propagation occurs via the amine nucleophilic attack at the carbonyl groups of the cyclic anhydride. The reaction is actually a step polycondensation, but it looks like a polyaddition or...
Photoinitiated Radical Polymerisation
Most of the radical-type photoinitiators used in UV-curable adhesives consist of aromatic ketones which are known to generate free radicals upon UV-exposure, either by homolytical cleavage of C-C bonds, or by hydrogen abstraction from a H-donor molecule 11 o c cr3 hv gt O C 'cr3 II 3 II 3 O C O RH hv gt O C R' II I Both the benzoyl and alkyl radicals initiate the polymerisation by addition to the monomer double bond. By contrast, the ketyl radical is inactive toward vinyl double bonds, so that...
Pressure Sensitive Adhesives PSAs
The concept of radiation-curable PSAs can be simply described as a rapid photoini-tiated cross-linking producing a viscoelastic material where the properties of tack, peel strength and shear resistance are predetermined 4 . It is this tackiness that causes the adhesive to stick instantly when pressed against a substrate. Depending on the peel strength, PSA tapes are considered as temporary for values below 350 N m, or permanent for peel strengths above this value. A strapping tape, which is...
Photoinitiated Cationic Polymerisation
Light-induced polymerisation is one of the most efficient methods to rapidly cure monomers that are inactive towards radical species, like vinyl ethers 49,50 or epoxides 51-54 . The subject has been recently covered extensively by Crivello and Dietlieker in an excellent textbook 55 . This technology has not yet achieved the commercial significance of corresponding free-radical processes, mainly because of the more limited choice of monomers available and their lower reactivity. The protonic...
Airless Spray
Airless spraying is based on the application of high pressure 30 to 400 bars to the adhesive, which is forced at high speed through a small orifice Fig. 25 b . As the adhesive exits the orifice and comes back to ambient pressure, it expands and breaks into fine particles. The size of the orifice determines the amount of filtration required impurities or other particles that are larger than the orifice would plug its opening. The type of adhesive and its viscosity, determine the pressure...
Facade Cladding
Elastic sealants based on synthetic elastomers such as polysulphides, silicones or polyurethanes allow the periodically alternating movements of building structures caused by temperature fluctuations to be followed in a consistent manner. It has gone unnoticed by some that owing to the development of modern elastomeric sealants, a new field of application has emerged - the load-bearing adhesive joint. The first step towards load-transmitting and movement-absorbing adhesive joints was taken...
Bonding of ParquetTimber Floors
Parquet floors need no longer be nailed as before but can be bonded or laid to float. Parquet floors can thus be laid in a time-saving manner without the need for a sub-floor. When bonding parquet onto the substrate, elastic parquet adhesives are the most appropriate for all materials involved, and are capable of adapting to the extremely different properties of wood and cement screeds. They ensure a durable bond of the parquet even under high mechanical and climatic stress. The good bond of...
Special Roll Coaters for Specific Machines
Many manufacturers of application machines are specialised in servicing a given industry, and for this industry they manufacture a range of machines which include applicators for glues and adhesives. For instance, many German companies are specialised in woodworking machines, Italian in footwear machines, etc. For their machines, these manufacturers have designed special applicators which fit to their customers' requirements. We will study here, briefly, some of their applicators, but these...
Heat Stable Adhesives
LOCTITE AEROSPACE-HENKEL TECHNOLOGIES 20021 Susana Road, Ran cho Dominguez, CA 90221, USA, Tel. 1 310-764-4600 PO Box 0994 Midland, MI 486686, USA, Tel. 1517-496-6000 18410 Butterfield Blvd, Morgan Hill, California 95037, USA, Fax 408 776-0700, 408 776-0107, www.brytetetech.com 260 Hudson River Road, Waterford NY, 12188-USA Tel. 1800-255-8886 2850 Willow Pass Road P.O. Box 312 Bay Point, CA 94565-0031, Tel. 925.458.8000, www.loctite.com Loctite Coporation, 82, rue de Maubec, 31300 Toulouse,...
Thermosetting Resins 1
Addition-type polyimides, which are thermosetting resins, were developed to improve the processability of polyimides, but their thermal stability is severely degraded by the presence of aliphatic bonds in place of the aromatic nuclei. However, the adhesive strength has been evaluated for the bismaleimide- Section 4.3.4.1 , bisnadimide- Section 4.3.4.2 and acetylene-terminated Section 4.3.4.3 imide oligomers. 4.5.3.1. Maleimide-Terminated Adhesives As previously stated, bismaleimides are...
Die Coaters
The idea that open systems do not protect the adhesives from evaporation and premature drying has led manufacturers to use closed systems, and the best one is the die or slot orifice, as shown in Fig. 53. These die or slot systems may be adapted on a roll coater. The opening of the slot may be adjusted very accurately as also the distance between the slot and the sheet and the angle. There are two types of slot die machines - those for water-based or solvent-based adhesives, - the heated slot...
Precyclised and Linear Polymers
As reported in Section 4.3.2.1, polyphenylquinoxalines are amorphous thermoplastic polymers which can be processed above their glass transition temperature. However, if not subsequently subjected to cross-linking reactions, the Tg constitutes the upper operating temperature of the bonded assembly. Another point to take into consideration with heat-resistant adhesives is that void-free bond lines can be obtained only if the solvents are completely evaporated before processing. This means that...
Equipment UV light
Ultraviolet Co. Lebanon, IN 46052, USA, Tel. 765 483-9514, 800 288-9288, Fax 765 483-9525, www.americanultraviolet.com Products UV equipment, Cure dose measurement, UV light sources, spot curing equipment, shuttered UV systems, application equipment CT 06810-7414, USA, 203 743-4059, Fax 203 792-2275, eluv electro-lite com, http www.electro-lite.com eluv Rue du Moulin de Poujard - Quartier Basleme 37160 Descartes - France Tel. 33 02 47 92 91 68, Fax 33 02 47 92 91 71, araytech wanadoo.fr,...
References
1 Rabilloud, G. and Sillion, B., European Polymer Journal, 1990, 26 9 , 967-976. 2 Rabilloud G. and Sillion, B., European Polymer Journal, 1990, 26 9 , 977-985. 3 Schwartz, H., Structural adhesives development, in Treatise on Adhesion and Adhesives, Structural Adhesives, Vol. 4. Marcel Dekker, New York, 1976. 4 Keimel, F.A., Historical development of adhesives and adhesive bonding, in A. Pizzi and K.a L. Mittal Eds. , Handbook of Adhesive Technology pp. 3-15 , Marcel Dekker, New York, 1974. 5...
Dry Film Adhesives
These are adhesive films which have been coated, usually on a carrier such as a non-woven or a plastic film, and then dried to provide a dry film of adhesive, which is supplied as rolls to the end users. Dry film adhesives provide several advantages - easy to use cut it to size, no need to apply a paste, - thickness of adhesive is perfectly controlled, - bonding viability the operator can check easily that they placed the adhesive in the joint. The adhesive may be cast either as a self...
Elastic Bonding in Practice
In this section, different applications of Elastic Bonding Technology are described. 6.8.1. Crash-Resistant Direct Glazing Adhesives One-component polyurethane adhesives for direct glazing are widely used in the automotive industry. Since about 5 of car's windshields every year are damaged, Drive-away time defines the 'fit-for-use' of vehicle after windshield repair. In case of an accident the bondline must withstand impact loading of 1. Airbag pushing against the windshield. 2. Momentum of the...
Roll Coating Different Techniques
Roll coaters may be used in two ways - either to coat sheets of paper, cardboard , labels, pieces of leather in footwear, - or roll stock such as rolls of paper, plastic films, aluminum foils. With open systems, water or volatile solvents can evaporate on the rolls. This causes thickening of the adhesive and consequently may cause a variation in the amount of adhesive applied. This can be aggravated if heat is generated by the shear forces resulting from mixing. When the rotation speed...