Adhesion formulations

The bulk physical properties of the polymers of the 2-cyanoacryhc esters appear in Table 2. AH of these polymers are soluble in /V-methy1pyrro1idinone, /V,/V-dimethy1foTm amide, and nitromethane. The adhesive bonding properties of typical formulated adhesives are Hsted in Table 3. 

Adhesives. Clays, especially kaolin and attapulgite, are widely used in various adhesive formulations. Adhesives (qv) containing clays can be derived from natural products such as starch or protein, or be whoUy synthetic, eg, latex, hot melt, emulsion, etc. 

Table 10. Resins Used to Formulate Adhesives, Sealants, Etc From Styrenic Block Copolymers...

T Urethanes not shown because of great differences in physical properties, depending on formulations. Adhesion characteristics should he related by actual test data. Any system which shows concrete failure when tested for surfacing adhesion should he rated excellent with decreasing rating for systems showing failure in cohesion or adhesion below concrete failure. 

In formulating adhesives, it is desirable to use materials with low cost. For specialty adhesives such as the acrylics, it is preferred to use commodity chemicals with a range of other uses. Minor components such as reactive rubbers, functional monomers and some additives are specially synthesized for acrylics, but these are expensive due to low volume. 

After metal pretreatment it is essential that a suitably formulated adhesive primer is used, because p.v.c. does not itself adhere to metals. 

Adhesive Formulation. Adhesives for testing consisted of 100 parts resin, 10 parts wheat flour as extender, 4 parts commercial additive, and 2 parts water. This formulation is recommended by Japanese board manufacturers. Adhesives without wheat flour were also formulated to examine the bond strength of the neat lignin based resins. 

Generally, the bonding obtainable with fire-retardant-treated wood is satisfactory for decorative purposes. Treated wood members can be bonded into structural assemblies with specially formulated adhesives under optimum bonding conditions (8). 

The formulator has the unenviable task of responding to the latest issues impacting the end users of adhesives and devising the technology and resources to come up with practical solutions. It may seem that as soon as a product is developed, tested, and commercialized, the demands change. This is, of course, not necessarily the fault of the end user. There are many outside influences that affect the end users processes, just as there are many influences affecting the type of raw materials and equipment that can be utilized for formulating adhesives and sealants. 

There are basically two types of epoxy acrylate resins used in formulating adhesive systems. One is a vinyl ester resin that is used in two-component adhesive formulations much as a DGEB A epoxy or a polyester resin is. The other is a special type of resin that is used in radiation cure processes. This latter type of epoxy acrylate does not have any free epoxy groups, but reacts through its unsaturation. 

The formulated adhesives are generally available as films or solvent solutions. They are commonly used as laminating adhesives for film or metallic foil because of their high peel strength. A composition consisting of a plasticized polyvinyl chloride copolymer and an epoxy resin can be cured with an aliphatic polyamine, which will crosslink by reacting with both resins. This adhesive possesses excellent adhesion to metals. 

Fillers can be used as pigments to provide color to the epoxy formulation. Adhesive coloring is used to match the color of substrates. Different coloring is often added to each component in a two-part epoxy as a method for determining efficient mixing of the components. The resultant color from the mixture helps the user know that the mix ratios are close and that the degree of mixing is sufficient. 

Nargiello, M., Hydrophobic Silicas Contribute to Consistency in Formulating, Adhesives Age, July 1989, pp. 30-31. 

Adhesion promoters are a group of specialty bifunctional compounds that can react chemically with both the substrate and the adhesive. The adhesion promoter forms covalent bonds across the interface that are both strong and durable. Adhesion promoters can be applied directly to the substrate, similar to primers, or they can be mixed with the adhesive itself. When mixed into the adhesive formulation, adhesion promoters are sometimes referred to as coupling agents because they can interact with both the substrate and the other fillers in the formulation. 

Several studies have shown that a microwave cure cycle can be developed that provides equivalent performance properties to a thermal cure cycle. Table 14.9 shows the processing and performance characteristics of three commercial one-component epoxy adhesives cured via microwave and conventional thermal energy. Certain commercial epoxy adhesives could contain a large number of bubbles due to volatiles present during the cure cycle and the fast rate of cure. Therefore, specifically formulated adhesives for microwave curing may be necessary to optimize performance. 

The reactions of amines and isocyanates are important in adhesives because of the possible reaction of isocyanates with water. Because isocyanates react readily with water, raw materials used in formulating adhesives must be dry, and the compositions must be protected from moisture, including atmospheric humidity, during storage. The first reaction... 

Although preliminary studies suggest that face-laminations can be obtained using adhesives made from condensed tannins that pass the standards of the American Institute of Timber Construction (< ), less is known about how to formulate adhesives using these materials for end-jointing of wood. This study, funded by the USDA Small Business Innovation Research Program, was undertaken to develop adhesive formulations containing 50% of sulfite extracts obtained from the bark of southern pine trees and demonstrate their use in... 

Monosaccharides (e.g., glucose), disaccharides (e.g., sucrose), and oligosaccharides can be obtained readily from natural sources, either directly or by hydrolysis of natural carbohydrate polymers. These can be used to either modify synthetic adhesive resins or to replace them altogether. In addition, reactive derivatives could be synthesized from these compounds and used to formulate adhesive polymers. 

Process aid (antifoam and deaeration agent in, e.g., paper and textile industry, in agrochemicals, dispersion production and formulation, adhesives)... 

Genamine. [Hoechst Celanese] Ethoxylated amines raw material for cosmetics, agric. formulations, adhesives. 

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