Latex adhesives solvent reactivation

A unified science of adhesion is still being developed. Adhesion can result from mechanical bonding between the adhesive and adherend and/or primary and/or secondary chemical forces. Contributions through chemical forces are often more important and illustrate why nonpolar polymeric materials such as polyethylene are difficult to bond, although polycyanoacrylates are excellent adhesives. Numerous types of adhesives are available such as solvent-based, latex, pressure-sensitive, reactive, and hot-melt adhesives. 

Uses Lubricant for two-stroke cycle engines, rubber, greases, textiles reactive intermediate for resins, plasticizers, surfactants antifoam in boiler water, latex processing solvent for inks and dyes antistat in cosmetics food-pkg. adhesives defoamer for food contact Manuf./Distrib. Aldrich Trade Names Ucon LB-285... 

Lamination (sticking together of layers) of fabric, foam and film, in various combinations, can be performed using latex- and solvent-based or fusible adhesives (see Adhesive classification). In addition, adhesives are sometimes applied from solution or latex for subsequent reactivation by heat during lamination. Acrylic dispersions are the main type of latex-based adhesives used in the laminating industry butadiene rubbers and polyurethanes are also utilized in smaller quantities. The latex-based adhesives are used for aesthetic reasons and also on heat-sensitive or open-structured fabrics. The solvent-based adhesives, for example rubbers and polyurethanes, are used in applications similar to those for latex adhesives. 

A second generation of phenolic dispersions, patented by J. S. Fry (33). involved the post dispersion of phenolic resins in a mixture of water and water-miscible solvents. To conform with air pollution regulations, the solvent was held to 20 volume %, or less, of the volatiles. A heat-reactive phenolic resin dispersion (34) and a phenolic-epoxy codispersion have become commercially available based on the above technology. Supplied at 40-45% solids, these products, which have a small particle size (0.75-1.0 ym), are better film formers than the earlier dispersions. Used alone or in blends with other waterborne materials, corrosion-resistant baking coatings may be formulated for coil coating primers, dip primers, spray primer-surfacers, and chemically resistant one-coat systems. Products of this type are also tackifiers for acrylic latexes, and such systems have been employed as contact, heat seal, and laminating adhesives for diverse substrates. 

Tetrahydrofurfuryl alcohol (THFA) is used to prepare tetrahydrofurfuryl acrylate and methacrylate in transesterification reactions with lower acrylate esters. These reactive monomers are used in the formulation of ultraviolet light-curable adhesives, coating, paints, and printing inks. THFA is an effective coalescing solvent for latex paints and is used in epoxy resin formulations. The oleic acid ester of THFA is used as a plasticizer for vinyl resin products. The high solvency of tetrahydrofurfuryl alcohol for dyes permits higher dye... 

These are multifaceted polymers that are utilized in a variety of applications and in many forms emulsion, solvent solution, 100% reactive, radiation-cured, and film. In the last dozen years, consumption of acrylic adhesives jumped 175%. Construction and pressure-sensitives accounted for most of this increase. In the former, acrylic latexes are making inroads on the territory held by SBR adhesive. In pressure sensitives, the acrylics (latex, solution, and radiation cured) make up one-third of the polymer demand. In this segment, acrylic latexes grew by ten times during the last twelve years. Acrylic solutions, used for making tapes and labels, are usually applied to film substrates. 

Second in importance come high-gloss applications, where cardboard or paper is laminated to a film in order to obtain a particular optical effect shiny or matt, for instance. The third area contains a variety of applications, e.g. flat antennas, microcircuits, insulation materials, under the heading technical laminations. Most of the time, these laminations involve metal foils or plates. While food packaging and technical laminations rely mostly on reactive two-component adhesive systems - solvent-based or solvent-free, based on polyurethane chemistry (for some applications dispersions are also used they can be made up of polyurethanes, acrylics or natural raw materials like latex and casein) - high-gloss... 

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