The utility of aqueous polymeric dispersions (also called aqueous polymeric emulsions) in the preparation of paints, coatings, adhesives and caulks or sealants is well known. Water based or water borne polymer dispersions are often preferred because of theft relatively low cost, ease of application and relatively low amounts of volatile organic compounds (VOC) contained therein. There is an increasing need for higher solids dispersions which will provide faster setting times for use on high speed production equipment. High solids adhesive bases may also find use as replacements for conventional hot melt (100% solids) material which requires elevated temperatures with consequent expenditures of considerable energy. In addition to the need for high solids dispersion for such applications, it is also essential that the dispersions remain sufficiently low in viscosity that they can be applied using conventional equipment. Considerable effort has been expended to provide aqueous dispersions of polymeric materials which are characterized by a high solids content.
Pressure-sensitive adhesives find use in a wide variety of applications, such as automotive, aerospace, construction and electrical markets, either in the form of tapes or as adhesive coatings on other backings. As the society becomes more aware of the significance of environmental protection, industrial products such as adhesive that is harmful to the ecological environment are gradually being replaced and eliminated.
Coated surfaces, especially those coated with modern low VOC coatings containing 100 g/L. VOC or less, such as moldings and panels often become visibly discolored after contact with water repeatedly or over extended periods of time. This problem is enhanced when high polymer content coatings are used on the surfaces. Other issues that can occur with painted surfaces are blistering and surfactant leaching, wherein water-soluble components are extracted from the coatings and deposited on the coated surface. Minimizing the amount of water-soluble ingredients has been used to reduce surfactant leaching. However, the water-soluble components are generally substituted with volatile organic compounds (VOCs), resulting in an environmentally undesirable product.
Surfactants have widely been used as emulsification, dispersion, cleaning, wetting and foaming. Emulsifiers for emulsion polymerization, which are used upon producing polymers by emulsion polymerization, are known not only to take part in polymerization-initiating reactions and polymer-forming reactions but also to affect the mechanical stability, chemical stability, freezing stability, storage stability and the like of the resulting emulsions. Further, they are also known to give significant effects on physical properties of the emulsions, such as particle size, viscosity and foaming potential and, when formed into films, physical properties of the films, such as waterproofness, weatherability, adhesion and heat resistance.
Surfactants can also be used as reactants, often called reactive surfactants. Surfactants used in polymerization are also called polymerizable and/or copolymerizable surfactants. Among the reactive surfactants, those containing one or more phenyl ether groups as hydrophobic groups have found wide-spread utility for their excellent properties such as emulsifying property, dispersing property, and polymerization-stabilizing property. Thus, surfactants that are based on alkyl phenol ethoxylates (APES) have been widely used in emulsion polymerization. In recent years, however, a concern has arisen about a potential problem that nonyl phenol ethoxylates may show false hormone effects on organisms to disrupt the endocrine system, that is, the so-called endocrine problem has arisen, so that research has also been conducted in efforts to provide replacements for the reactive surfactants containing one or more phenyl ether groups.
Accordingly, there is a need in the art for an aqueous dispersion and/or emulsion with ultra-high solids but environmentally friendly in preparations and applications.