Thermoplastic solution acrylic resins

Thermoplastic solution acrylic resins were the first type of acrylics to be commercialised in the 1930 s, for speciality uses. In the 1950 s they began to be used for automotive applications, in the United States, replacing nitrocellulose based finishes and synthetic enamels. They offered significantly improved colour, colour stabibty and exterior durability over other polymers of similar cost. Thermoplastic acrylics are prepared by the homo/copolymerisation of acrylic monomers and are usually regarded as inert. Today two main classes of thermoplastic acrylics are commercially available ... 

The viscosity of solution polymers increases directly with molecular weight. Performance properties begin to plateau as molecular weight increases, but viscosity continues to increase. Thermosetting solution acrylic resins are polymerized to lower molecular weight than thermoplastic acrylics, since they attain their property performance by conversion to infinite three-dimensional networks by chemical reaction (forming primary chemical bonds). 

Thermoplastics in the form of a lacquer have poorer mechanical strength than the thermosetting resins but are more easily removed, should this prove necessary. Polyvinyl acetate and polyurethane are good examples of this class of consolidants, particularly on wrought iron artefacts. Many of the copper and copper-based alloys, such as bronzes and brasses recovered from the Mary Rose, were consolidated with a solution of acrylic resin dissolved in toluene (Incralac). 

Extensional flow can also be encountered in spray application. If, for example, a solution of a thermoplastic acrylic resin with above about 100,000 is sprayed,... 

As mentioned above, both thermoplastic and thermosetting type acrylic resins are commercially available for coatings, elastomers, sealants and adhesive applications. These resins are supplied in many different delivery forms such as powders or pellets, solutions in organic solvents and aqueous dispersions. These resin types are briefly described below. 

The term solution acrylics refers to acrylic resins prepared by chain-growth polymerization using a solutionbased polymerization process. Here, acrylic monomers and initiators are slowly added to an organic solvent and polymerization is carried out at a predetermined temperature and inert atmosphere with efficient stirring. Both monomers and the polymer formed are miscible in the selected solvent. With the progress of polymerization, the solution viscosity will Increase and heat transfer becomes difficult, limiting the solid content of the final solution. Both thermoplastic and thermosetting solution acrylics can be prepared by this technique. 

The use of thermoplastic acrylics in high build, heavy duty anti-corrosive systems is reported by Steed who describes top coat formulations based on thermoplastic acrylic resins, chlorinated rubber, solution vinyl resins as well as blends of two or more of these. 

Paraloid Thermoplastic Solution Grade and Solid Grade Acrylic Resins for Industrial Finishing. Rohm + Haas Publication Nov. 1991. 

In some examples it is not necessary to prepare the organometallic-coupling agent R2MX2 beforehand. Thus coating glass fibres with a heptane or alcohol solution of titanium alkoxide promotes adhesion between the fibre and polymer, e.g., acrylic, polyolefins, polyester, polyamide and other thermoplastic resins. 

Acrylics are thermoplastic resins based on acrylates or derivatives such as amides and esters. Acrylics are available as emulsions, solvent solutions, and monomer—polymer mixtures (one or two components) with a catalyst. Emulsion—solvent types set by evaporation and absorption of a solvent. Polymer mixtures set through polymerisation by heat, ultra-violet radiation and/or the action of a chemical catalyst. 

Solution thermoplastic acrylics form coherent films simply by solvent evaporation without post-filming reactions taking, place. Therefore, the properties of thermoplastic resins depend primarily on the necessity of physical entanglements between long chain molecules and secondary bonding forces (<5 kcal/mole). Thus, it is possible to obtain with the same monomer... 

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