Cyanoacrylate glass bonding

Environmental performance The durability (see Durability - fundamentals) of cyanoacrylate adhesive bonds is reasonably good on rubbers and some polymer substrates. However, on glass and metals, both thermal and moisture durability are low. 

In many cases, glass and even porcelain bondings are carried out as repairs in households. In such cases, it has to be pointed out that, compared to the two-component reactive adhesives, in particular epoxides, cyanoacrylates show only a limited bond strength in the face of high temperature and humidity stress in connection with rinsing agents in the cleaning equipment. 

During the transformation of a monomer into a polymer, many atoms separated by van der Waals distances ( 5 A) participate in the formation of covalent bonds (1-3 A). Therefore during polymerization, an increase in the macroscopic density ensues, while on the molecular level a decrease in free volume and entropy occurs while the cooperativity of motions increase. Concomitantly the glass temperature can increase by more than 100 °C. Several important adhesive systems are based on this increase. The cyanoacrylate Super Glue starts as a monomer with a Tg <0 °C and it polymerizes to a linear soluble polymer with a Tg which is in the neighborhood of 100 °C upon appUcation under anaerobic conditions. For linear polymers the simple equation [74]... 

Methyl-2-cyanoacrylate n. A fast setting adhesive used for bonding cellulosics, nylon, polyesters, acrylics, polystyrene, and polyurethanes to each other and to other materials such as woods, metals, and glass. Catalyzed by atmospheric moisture or lightly applied methanol, the adhesive polymerizes without loss of solvent. For best results, the surfaces to be bonded should mate closely. 

Anaerobic sealants Cyanoacrylates Ultraviolet-cured sealants Methyl methacrylate Metal and glass glues Epoxy diacrylates (vinyl resins) Acrylic dental bonding agents... 

Ethyl cyanoacrylate is contained in instant glues for metal, glass, rubber, plastics, textiles, tissues and nails. It polymerizes almost instantaneously in air at room temperature and bonds immediately and strongly to surface keratin. Beauticians are exposed to contact dermatitis from nail glues. 

Cyanoacrylates are not recommended for permanent bonding of rubber to glass or glazed ceramics as the cyanoacrylate will de-bond from the glass after a relatively short time (typically 1-6 weeks). 

On the exterior of the vehicles, rubber profiles around windows and doors and the trunk lid are "lap bonded with cyanoacrylate adhesives because continuously extruded profiles cannot be used for sharp comers. To obtain effective sealing and better sliding in the case of sliding windows, these profiles are flocked by means of polyurethane-based flocking adhesives. The lenses of headlamps are joined to the housing by polyamide or polyurethane hot-melt adhesives and epoxy resins. The layers of laminated safety glass are bonded with a film based on poly(vinyl butyral). 

Refractive Index Cyanoacrylates - Of interest in the bonding of clear plastics and glass. See data sheet Notes for other classes (if stated). 

The extremely fast cure (seconds to minutes), low viscosity (mPas), and ability to form strong bonds with many substrates, including glass, ceramic, aliuninum, steel, rubber, plastic, wood, and their combinations, make the cyanoacrylates excellent for assembly line bonding. These adhesives have good solvent resistance but show some loss in bond strength on aging in water and in air at temperatures above 212°F (100°C). 

Epoxies generally have excellent adhesion to metals, ceramics and glass, although on most amorphous thermoplastics epoxies will usually he outperformed by MMA, UV adhesives or cyanoacrylates. Epoxies will bond well to thermoset plastics and are widely used for bonding sheet moulding compound door and body panels in the transportation industries. Epoxies do not adhere well to elastomers, fluoropolymers or polyolefin plastics. 

Perhaps one of the most fundamental and key properties associated with the selection of the adhesive is to make sure that it bonds well to the two materials selected. Cyanoacrylates generally have good affinity to plastics and a good number of ultraviolet (UV) adhesive grades are also particularly suited for plastics, whilst other UV adhesives (with silane additives) are more suitable for glass - the product data sheet should be studied carefully to ensure compatibility with both adherends. Epoxies are good general-purpose products and can show excellent adhesion but are slower cure. 

Glass is difficult material to stick, particularly if it is to be exposed to very humid or wet conditions. It must be thoroughly degreased, abraded and dried before applying adhesive. Cyanoacrylates are only really suitable for light duties in dry conditions, the bond is likely to fail under humid conditions. 

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