Epoxy-phenolic-nitrile adhesive

In addition to epoxy-phenolic adhesives three-part epoxy-phenolic-nitrile rubber systems are used in metal-metal edge joints and honeycomb constructions [208], These add toughness not available in most EP systems and improve peel strengths. When used on honeycomb, the NR-P is normally applied to the aluminum skin and the EP to the honeycomb for assembly. Service temperature limitations are those imposed by the NR-P part. 

Several important types of adhesives used to obtain high-strength bonds are the epoxies, epoxy -phenolics, nitrile-phenolics vinyl-phenolics... 

Polymer blends are often used in adhesive formulations where properties associated with rigid polymers (high temperature resistance, chemical resistance, etc.) must be obtained along with properties associated with tough, elastic polymers (impact strength, high peel strength, etc.). Examples of these adhesive systems are nylon-epoxy, phenolic-nitrile, epoxy-polysulfide, epoxy-nitrile, and epoxyurethane. 

Several specialised adhesives are available for extreme high-temperature service. These include epoxy phenolic, nitrile phenolic, quinoxaline [1] bismaleimides [2-4], polyimide [5, 6], and polybenzimidazoles [7]. They are used mainly in aerospace applications [8]. 

Film adhesives They resemble hot melts and heat-activated adhesives in the sense that heat is used for activation with a subsequent cure schedule, which may include additional heat application under pressure. They may contain lightweight fabrics, nylon, polyester, glass mats in the form of carrier cloth. Thus, the adhesive thickness may be controlled uniformly. Epoxies, phenolics, nitrile-elastomers, polyamides, PVC, polyvinyl butyl, ethylene-carbolic acid copolymers are available in film form with or without carrier cloths. 

Five of the most important two-polymer adhesives used in films and tapes include vinyl-phenolics, epoxy-phenolics, nitrile-phenoUcs, nylon-epoxies, and elastomer-epoxies. Neoprene-phenolics are available in organic solutions and in supported and unsupported... 

Adhesives recommended include epoxies, nitrile-epoxy, nitrile-phenolic, PI, and epoxy-phenolic. PI adhesives provide strengths of 11.0—12.4 MPa at 316°C. These adhesives are not used for skin-to-core bonds because the... 

Adhesives recommended are epoxies, phenolic-polyvinyl butyral, epoxy-phenolic, nitrile-phenolic, polyurethane, neoprene, butadiene-nitrile mbber, cyanoacrylates, resorcinol-polyvinyl butyral, furane, and urea-formaldehyde. 

The most common aerospace adhesives include nitrile epoxy systems, epoxy polyamides, epoxy phenolics, and various unmodified epoxies [18]. Polyimides... 

The early aerospace adhesives were primarily based on epoxy resin chemistry. However, unique applications requiring high temperatures and fatigue resistance have forced the development of epoxy-phenolic, epoxy-nitrile, epoxy-nylon, and epoxy-vinyl adhesives specifically for this industry. The aerospace industry has led in the development and utilization of these epoxy-hybrid adhesives. 

Typically tape or film epoxy adhesives are modified with synthetic thermoplastic polymers to improve flexibility in the uncured film and toughness in the cured adhesive. Epoxy resins can also be blended with phenolic resins for higher heat resistance. The most common hybrid systems include epoxy-phenolics, epoxy-nylon, epoxy-nitrile, and epoxy-vinyl hybrids. These hybrid film adhesives are summarized in Table 13.2, and structural properties are shown in Table 13.3. 

FIGURE 15.17 Effect of adhesive on the durability of etched 6061-T6 aluminum alloy joints exposed to a marine environment. (1) Two-part epoxy, (2) one-part epoxy, (3) nitrile-phenolic, (4) vinyl-phenolic, (5) vinyl-phenolic.33... 

Epoxy and nitrile-phenolic adhesives have been used to bond polyolefin plastics after plasma surface preparation. Shear strengths in excess of 3000 psi have been reported on... 

Structural adhesives that are commonly used for composites are supplied in two basic forms semisolid B-stage film and thixotropic pastes. The film adhesives are cast or extruded onto carrier fabrics or films and partially cured to a semisolid. They can easily be handled, cut, and applied to the joint area. There is no need for mixing, metering, or dispensing of liquid components. In use, these adhesive systems are activated by heat and pressure. The semisolid B-stage film liquefies briefly on application of heat and then cures to an insoluble state. Epoxy, polyimides, epoxy-nylons, epoxy-phenolic, and nitrile-phenolic adhesives are available as B-stage film. 

Polyethylene and Polypropylene Acceptable bonds have been obtained between treated polyolefin surfaces with polar adhesives, such as epoxies, or solvent cements containing synthetic rubber or phenolic resin. The solvent adhesives are applied to both surfaces and the solvents allowed to evaporate before the parts are joined. Recommended epoxies are the anhydride-cured and amine-cured types. Also suitable is a two-component, polyamide-modified epoxy compound. Other adhesives that provide adequate bond strength to treated polyolefins include styrene-unsatmated polyester and solvent-type nitrile-phenolic (15). 

Phenolic Adhesives recommended are neoprene and urethane elastomer, epoxy and modified epoxy, phenolic-polyvinyl butyral, nitrile-phenolic, polyester, cyanoacrylates, polyurethanes, resorcinols, modified acrylics, polyvinyl acetate, and urea-formaldehyde (1). 

Epoxies are not the only resins used in aerospace bonding. A common formulation is a nitrile/phenolic film adhesive. A typical formulation may consist of the following (pbw) ... 

According to one author, epoxy-phenolic adhesives for high-temperature applications were developed during World War II at Forest Product Laboratories in Madison, Wisconsin, and nitrile phenolic adhesives shortly after World War II [9, pp. 153, 156]. A patent for epoxy resins was applied for in Germany in 1934, and the inventor disclosed that it could be hardened with equivalent amounts of amines, diamines, or polyamines and that it showed strong adhesion [14, p. 8]. Epoxy resins are believed to have been commercialized in the United States first by the former Jones Dabney Company sometime after 1942. 

Chem. Descrip. N-(2-Aminoethyl-3-aminopropyl trimethoxy silane CAS 1760-24-3 EINECS/ELINCS 212-164-2 Uses Adhesion promoter and pigment treatment for coatings, adhesives coupling agent used for epoxies, phenolics, melamines, nylons, PVC, acrylics, polyolefins, polyurethanes, nitrile rubbers food pkg. adhesives Regulatory FDA 21CFR 175.105,175.300 Use Level 0.05-16%... 

Structural adhesives are not usually applied directly to the prepared metal. Rather, a primer is applied first. The primers are usually of the same generic chemical composition as the adhesive being used over them (i.e., epoxy primer to epoxy adhesive). The primers may or may not contain a corrosion inhibiting pigment and may or may not have to be cured before application of the adhesive. EC-1593 is a 350 F (121 C) curing nitrile-phenolic primer while EC-3917 is a chromated epoxy-phenolic primer curing... 

In this Institute, there are approximately 200 research personnel and one fourth of them are working on adhesives in two laboratories, one pilot-plant, one testing group and one adhesive-film manufacturing and testing facility. Their research and development broadly covered structural adhesives, strain gauge adhesives, wood adhesives, second-generation acrylics, anaerobic adhesives and composite binders. Their products varied from J-01 to J-53. There were at least thirty different kinds of adhesive and sealant, for example, nitrile-phenolics, modified epoxies, acrylics and epoxy-phenolics. 

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