Anaerobic adhesives Plates

Glass plates varying in the surface roughness were used as model substrates in our experiments. The roughness was smoothed out by replication of supersmooth etalon surfaces of polished Si wafers. For replicate layers we used thin films of acryl anaerobic adhesives and photopolymer compounds. 

CAS 109-16-0 EINECS/ELINCS 203-652-6 Uses Adduct monomer for preparation of anaerobic adhesives and sealants, castings, plastisols, coatings, fibers, cast acrylic sheets, elec, photoresists, rubber prods., dental resins, overprint varnishes, and flexographic printing plates crosslinks and copolymerizes with other vinyl monomers imparting solv. resist., heat resist., and hardness Properties Pt-Co 100 max. clear liq. m.w. 286 vise. 10 mPa-s flash pt. 

Adhesives may also be classified by the way they are applied or cured. Hence, anaerobic adhesives are adhesives that set only in the absence of air, for instance, when confined between plates or sheets. A contact adhesive is one that is apparently dry to the touch but will adhere to itself instantaneously on contact (also called contact bond adhesive and dry bond adhesive). A heat-activated adhesive is a dry adhesive film that is made tacky or fluid by application of heat or heat and pressure to the assembly. A pressure-sensitive adhesive is a viscoelastic material that in solvent-free form remains permanently tacky. Such materials will adhere instantaneously to most solid surfaces with the application of very slight pressure. Room-temperature setting adhesives are those that set in the temperature range of 20-30°C. These are usually two-component adhesives that must be mixed before application. A solvent adhesive is an adhesive that has a volatile organic liquid as a vehicle and sets or becomes tacky after the solvent has evaporated. A solvent-activated adhesive is a dry adhesive film that is rendered tacky just before use by applicafion of a solvent. 

Plate 2 Anaerobic adhesive is used to retain the oil-impregnated bush shown at the centre. Its use here, and for the re tension of the bush supporting the end of the drive shaft, enables the gears to take up the correct spatial alignment without recourse to rigorous accuracy in their respective housings. Material Permabond A115. 

Plate 3b Application of the anaerobic adhesive prior to insertion. Several years after being repaired the bonded components are still giving daily service. Material Casco ML Grade MLF118. (Photograph courtesy Delo GMBH.)... 

Plate 4 Anaerobic adhesives and sealants are used extensively in the assembly of engines built by Lotus Cars. The one illustrated is the turbo-charged 2.2 litre engine. (Photograph by Focalpoint, courtesy Lotus Cars Ltd.)... 

Plate 6 The flywheel of the 2.2 litre Turbo is retained with six bolts. These are treated with an anaerobic adhesive to prevent loosening. Considerable stresses are involved for the flywheel can rotate up to 7000 rpm. Not only must the anaerobic adhesive prevent the loss of tension within the bolts but it must also seal the thread in order to prevent oil loss. Material Permabond A115. (Photography by Focalpoint, courtesy Lotus Cars Ltd.)... 

Plate 10 a Prior to fitting the piston head (Plate 11b) to the threaded end of the piston rod, the thread is treated with an extremely strong anaerobic adhesive to ensure that the assembly torque is maintained and that the piston is held firmly in position. The larger threaded component (left centre) is the ram cylinder end cap (see Plate 11b). Material Permabond APP460. (Photograph courtesy JCB Ltd.)... 

These types of adhesives remain fluid in the presence of oxygen but cure to solids in its absence. The simplest anaerobic adhesive consists of dimethyl acrylate ester with the peroxide catalyst system and accelerator. They cure by free-radical polymerization in the absence of oxygen. Anaerobic adhesives have strength characteristics equivalent to those of the structural adhesives. One-part anaerobic adhesives cure at room temperature in several hours, but their cure can be accelerated to minutes by high-temperature cure and by the use of certain primers/ accelerators. Such elevated temperature, primer/accelerator-assisted cure is especially recommended when anaerobic adhesives are used on inactive surfaces, such as unclean metals or plastics, or inhibiting surfaces such as plated surfaces, chromates, oxides, and anodized surfaces. 

This adhesive group has been promoted for use as a sealant. The adhesives used are acrylate acid diesters (polyester-acrylic). They are essentially monomeric thin liquids that polymerize to form a tough plastic bond when confined between closely fitting metal joints. Contact with air before use keeps the monomeric adhesive liquid. Metal surfaces accelerate the polymerization in the absence of air (anaerobic conditions). These materials will bond all common metals, glass, ceramics, and thermosetting plastics to each other. Phenolic plastics and some plated metals, such as cadmium and zinc, require a primer such as ferric chloride. Polymerization is essentially a free-radical-type addition polymerization. " ... 

Of the high-performance adhesives there is little doubt that anaerobics are uniquely capable of supplementing the retention and sealing of cylinder liners -both wet and dry. Only the strongest versions should be used and, in the most demanding circumstances, probably only the toughened variants will suffice (see Plate 17). 

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