Preparation primer compositions

The Effect of Adhesive Primers. In practice, adhesive bonds involving metal adherends often use primers as pretreatments of the metal surface prior to bonding. Table IV shows the durability of composite-metal bonds prepared with adhesive C over a series of primers (of varying corrosion resistance) in 240 hour salt spray test. The results indicate that the performance of bonds is directly related to the corrosion resistance of the primer used to prepare the adherend surface. In general, the adhesion of the primer to the steel adherend, rather than the adhesive chemistry. 

This work discusses the structure of films formed by a multicomponent silane primer as applied to an aluminum oxide surface as well as the interactions of this primer with the adhesive and oxide to form an interphase region with a distinct composition and properties. The mecanical properties and durability of adhesive joints prepared using this primer system have yet to be evaluated. 

IR data. Spectroscopic techniques were then employed to determine more about the composition of the fracture surfaces. ATR of the adhesive side of the fracture surfaces showed only slight differences in the composition of the organic phase near the interface as a result of applying primer to the adherend surface before applying the adhesive. The spectrum shown in Fig. 7C (obtained with the 45° KRS-5 reflection element) is the difference between a sample prepared from an unprimed adherend (Fig. 7B) and one prepared from a primed... 

CHAPTER 17 THE PREPARATION OF NITRO TETRAZOLES LNTA forms heavy, granular, yellowish white crystals, which are not very soluble in water—the crystals are more readily soluble in hot water. LNTA detonates when heated to 220 Celsius, and is slightly more percussion sensitive then mercury fulminate as a result, its use in priming compositions has been questioned, but it can be safely desensitized by mixing with dextrose, flour, or gum Arabic immediately after preparation. The desensitized product can be successfully used in priming compositions for use in bullet primers and the like. ... 

The hardcoat is a silicone-silica composite prepared by hydrolysis of alkoxysilanes in the presence of water and colloidal silica, and can contain an alkoxysilylated UV absorber for protection of the polycarbonate. Adhesion of the topcoat to polycarbonate is provided by a primer, which is a solution of acrylic polymer. The primer is coated on polycarbonate and air dried to a 0.5 pm thick film. The topcoat is applied over the primer layer and air dried before curing at 130 °C for at least 30 min. 

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 addition to the solvents used in adhesives, solvents are needed for surface preparation and primers. Their composition may vary and is usually designed for a particidar substrate, often using fast evaporating solvents and environmentally unfriendly materials with significant adverse health effects. 

They dominate the field of wood adhesives and represent one of the largest volumes of any synthetic adhesive. Phenolics are also among the lowest-cost adhesives and may be formulated as water dispersions, to allow penetration into the cell structure of wood which is important for the formation of permanent bonds. Beyond the wood and wood products area, unmodified phenolics are used mainly as primers, to prepare metal surfaces for bonding, and as binders, for such varied products as glass wool insulation mats, foundry sand, abrasive wheels, and brake lining composites. Phenolics are supplied either as one-component, heat-curable liquid solution, as powder, or as liquid solution to which catalysts must be added. The curing mechanisms are different for these two groups. "... 

Mitsubishi Chemical manufactures a seismic retrofit material Replark and have formed a joint venture with Fiberite in the USA. Replark is a UD carbon fiber tape with low epoxy resin content with a fiberglass scrim backing to facilitate handling in the field. The application entails the preparation of the concrete, application of an epoxy primer, putty and resin, followed by the requisite number of layers of Replark tape and additional resin, to form a cured composite and finally, the application of a surface coat to improve the appearance. Fiberite use type 12k T300 or AS4C carbon fiber and the Replark is offered in areal weights from 175 300 gm . ... 

Corrosion protection by ICPs has been well documented in several reviews [136-141]. The use of ICP-based core-shell latexes for the corrosion protection of steel is a relatively new field of research, and a recent review has proposed the exploitation of such possibihties [142]. In a recent study, we found that ICP-based core-shell latexes offer the possibility of achieving anticorrosion properties [143], though the presence of pinholes or scratches in the coatings enhances the corrosion rate of metals. This problem may be due to poor dispersion of the composite particles in the insulating resin systems, and future research will need to develop conductive polymer-based anticorrosive primers for metals. The anticorrosive properties of PANI-coated polystyrene latex microspheres has been reported recently [144]. PS-PANI composite particles with core-shell structure were prepared by chemical oxidative polymerization of anihne monomer in the presence of a PVP-stabilized PS latex suspension. The reduced form of the particle was obtained by adding hydrazine mono hydrate to the suspension. Both oxidized and reduced PANI-PS particles were used to obtain a PANI-PS-coated iron electrode (PANl-PS-Fe). Pure PANI... 

Also, as the thickness of the adhesive bondline increases, read through problems become worse. The heat resistance of urethane-bonded SMC composites has also been a problem. This is believed to be due to the out-gassing of volatiles from the plastic which decreases the bond integrity. This is evidenced in Table VI, which compares the heat resistance of metal-metal bonds and SMC composites prepared with urethane adhesives. It can also be seen that the composition of the SMC has a significant affect on the heat resistance. The urethane-modified SMC was also reported to give off less volatiles than the unmodified SMC. Recent work has indicated that certain primers may be able to protect the adhesive from the substrate. 

Once cleaned, the metal surfaces are coated with a primer prepared by rollmilling 200 g of adhesive composition and 5(X) g of methanol. A first layer of primer is appUed to the metal parts, dried for 10 min at 90°C, covered with a second layer of primer and finally dried at 90°C for 1 h in an air circulating oven. The adhesive film is inserted between the two primed metal surfaces and the assembly is placed between the platens of a hydraulic press preheated to 316°C. A pressure of 0.3-0.5 MPa is applied and the test specimens are cured at 316°C for 1.5 h, before cooling down to 100°C under pressure. The assemblies are removed from the press and postcured in an air circulating oven as follows the temperature is raised from 20 to 300°C in 1 h, then from 300 to 350°C in 5 h and left at 350°C for 5 h. The lap shear strength values determined at different temperatures are plotted in Fig. 29 for TU-2 Ti/li assemblies [curve (a)] and ZIO CNT 1810 stainless steel coupons [curve (b)]. 

Adhesive monomers were dissolved in ethanol at a concentration of 5 wt% to form bonding agents. The primer was prepared by mixing compositions A and B in Table 1 for 30 sec just before use. Dimethyl-p-toluidine in composition A was the accelerator for the initiation with benzoyl peroxide by a redox mechanism. 

Barium styphnate has been used for firearms in Britain since World War II [2]. The type of production process and shape of prepared crystals determines the application of this primary explosive. It is used in delay composition, as an ingredient of primary compositions, as a component of compositions for electric primers or igniters, delay compositions, and so on [2, 3, 75, 76]. 

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