Dispersion Acrylic

Acrylic acid, the main precursor to acrylic adhesives had been synthesized in the mid 1800s and the first acrylic acid esters were made and characterized at the turn of the century [62]. The first commercial launch of acrylic polymers in the form of poly(methylmethacrylate) took place in 1927 when the German company Rohm and Haas AG introduced this new plastic to the market. Soon after, other companies such as BASF introduced acrylic dispersions. 

Chlorinated vinyl acrylic dispersions (for epoxide adhesives)... 

The consumption of polymer dispersions in 1997 was 10xl06 t. The market is divided among styrene-butadien dispersions (35 %), dispersions containing vinyl acetate (32 %), styrene and styrene-acrylate dispersions (25 %) and others in minor quantities. They have many applications coatings and paints, adhesives, textile finishing, paper coatings and others. When used as coatings the dispersions should be suitable for food contact. Many substances can be used as monomers ... 

The waterborne basecoat consists of a urethane or an acrylic dispersion with passivated aluminum for metallic glamour. The aluminum must be passivated to prevent reaction with water and the evolution of hydrogen gas. Passivating agents can include polymers, hexavalent chromium (now mandated for removal), or phosphate esters. The basecoat is pre-baked (with infrared or thermal ovens) to release the majority of the water prior to clear-coat application. 

Relationship of Morphology to Mechanical Properties of Rapidly Polymerizing Acrylic Dispersions... 

Figure 1. Impact fracture surface of polymerized acrylic dispersion, no dimethacrylate, SEM 17.5X...

Figure 6. Flexural (0.05 in./min) fracture surface of polymerized acrylic dispersion containing 12% tetraeth-ylene glycol dimethacrylate, SEM 16 X...

Figure 7. Fracture surface of the interface of a molded acrylic artificial tooth with polymerized acrylic dispersion (60 vol % beads), SEM 850X...

Figure 9. Fracture surface of polymerized acrylic dispersion (67 vol % beads), polarized transmitted light microscopy 68 X...

Figure 12. Oscilloscope trace of impact fracture of polymerized acrylic dispersion time scale = 50 fisec per division...

The mechanical properties of rapidly polymerizing acrylic dispersions, in simulated bioconditions, were directly related to microstructural characteristics. The volume fraction of matrix, the crosslinker volume in the matrix, the particle size distribution of the dispersed phase, and polymeric additives in the matrix or dispersed phase were important microstructural factors. The mechanical properties were most sensitive to volume fraction of crosslinker. Ten percent (vol) of ethylene dimethacrylate produced a significant improvement in flexural strength and impact resistance. Qualitative dynamic impact studies provided some insight into the fracture mechanics of the system. A time scale for the elastic, plastic, and failure phenomena in Izod impact specimens was qualitatively established. The time scale and rate sensitivity of the phenomena were correlated with the fracture surface topography and fracture geometry in impact and flexural samples. 

Degen, A. and Kosec, M., Influence of pH and ionic impurities on the adsorption of poly(acrylic) dispersant onto a zinc oxide surface, 7. Am. Ceram. Soc., 86, 2001, 2003. 

Sulphosuccinic acid diesters play a role above all in American polymerization formulations. They are rarely used as principal emulsifiers, but rather to control secondary properties, for example, for the production of highly concentrated low viscosity acrylate dispersions. The branched sodium di-2-ethyl hexyl sulphosuccinate is widely used, combining favourable emulsifier properties with excellent wetting power. Dicyclohexyl sulphosuccinate has a particularly high CMC and a particularly high surface tension [48]. 

Acrylate dispersions are among the best performing aqueous adhesives, since they require no plasticizers to render them flexible and allow no plasticizer migration from the plastic materials (impermeable boundary). These dispersions are therefore always used in products in which hazards to humans must be excluded, for example in wound bandages. 

Solubilizable Dispersions (19). The chemistry of solubilizable acrylic dispersions is a hybrid of emulsion and water-reducible technology. These polymers are synthesized by emulsion techniques but contain acidic or basic functionality that renders them water soluble upon neutralization with an appropriate titrant. For example, if the solubilizing functionality is acidic, the polymer will behave like an emulsion below a certain critical pH range, like a highly swollen emulsion within the critical pH range, and like a true water-soluble polymer at sufficiently high pH values. Such polymers offer a favorable balance of properties for many coating applications. 

Asterite. [ICI Chem. Polymers Ltd/ Acrylics] Acrylic dispersions. 

Colloid. [Rhone-Poulenc/Perf. Resins Coatings] Polycarboxylate salts, acrylics dispersant, vise, stabilizer for paints defoamer latex processing aid. 

Products of Emulsion Polymerizalion. This is the most useful process for polymerizing the acrylate esters, producing stable dispersions with excellent film-forming properties. These acrylate dispersions are employed in the paper, rubber, textile, leather, and paint industries. 

In the paper industry, acrylate dispersions are used for clear, greaseproof coatings, as binders for clay coatings, and as heat-sealing adhesives. 

The application having the greatest possibilities for growth is emulsion paints. Paints made from acrylic dispersions have tire usual desirable properties associated with acrylic polymers, particularly color retention,... 

At the phenomenological level it may be known that Solvent A works well with acrylic dispersions while Solvent B is better for vinyl dispersions. Experimentally the important question of how much to add can be determined by systematic experimentation. However, for fine tuning some theoretical knowledge about the influence of transient solvent on the glass transition temperature (Tg), and tihe influence this will have on the minimum film forming temperature (MFT) is usefiil. This would undoubtedly lead to some consideration of the distribution (partitioning) of the solvent between the aqueous and polymer phases, which can be... 

In conventional exterior-use paints SB dispersions have largely been replaced by styrene-acrylate dispersions, and their use is now restricted to special applications (corrosion protection primers, wood primers, mortar modification) where low film permeability to gases, water vapor, etc., and complete resistance of the polymer to hydrolysis are necessary. In order to achieve a uniform surface and thus improve printability, paper and card are coated with paper-coating colors. Carboxylated SB dispersions are used in these paints as binders. 

Aqueous acrylic dispersions are being increasingly used for wood coatings or corrosion protection coatings. These paints are often not baked instead, mechanical... 

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