Cross-linking polymerization of acrylic monomers

Acrylic monomers useful in the production of films, coatings, moldings and the like are cross-linked in polymerization by a process which comprises irradiating acrylic acids, methacrylic acids and esters thereof with radiation in the presence of 10-2 to 5.0 mole percent of acetylene derivatives substituted by hydrogen radicals of aliphatic or aromatic hydrocarbons leaving one of the two hydrogen atoms to bind to carbon atoms of acetylene. The products have superior mechanical properties, heat resistance and corrosion resistance to chemicals. Cross-linking polymerization has been discovered between acrylic acids and derivatives thereof in the presence of a small amount of acetylene. This method is provided by using acetylene derivatives in the form of a liquid at room temperature and pressure. Further, the polymerization can be carried out by efficiently by irradiating with ionizing radiations or ultraviolet radiations at a high dose rate, generally 10 to 106 roentgen per second. In one of the examples, 2 cc of methyl methacrylate and 70 g of azobisisobuthyl nitrile were sealed in an ampoule together with 24.7 mg of propine-1 and kept at 400C for 16 hrs. A clear solid was produced with no soluble methyl methacrylate detected, and a gel content of 100%. In another example, 2 cc of methacrylate and 24.7 mg of propine-1 were polymerized with ultraviolet radiations from a 250W mercury arc lamp for 5 hrs with similar results. (Iwakiri, K.)