synthetic latices; products of the copolymerization of diene hydrocarbons with vinylpyridines or their homologues. The most common vinylpyridine latices are copolymers of butadiene (I) and 2-methyl-5-vinylpyridine (II); their general formula is
The content of vinylpyridine monomer units in vinylpyridine latices does not exceed 30 percent. Ternary copolymers, which contain styrene, acrylonitrile, and methacrylic mers in addition to the vinylpyridine mers, are also known. The density of vinylpyridine latices is 0.92-0.98 g/cm3, and their glass-transition temperature is about 70° C. They are soluble in benzene, toluene, and gasoline; latices containing more than 15 percent vinylpyridine are soluble in ketones and esters. Because of the presence of pyridine groups, vinylpyridine latices are comparatively resistant to the action of ionizing radiation. The ability of the pyridine groups to undergo various chemical reactions makes it possible to use not only systems containing sulfur and organic accelerators but also those containing metal chlorides and organic halogen-containing compounds, such as tetrachloroquinone, for the vulcanization of vinylpyridine rubbers. Black-filled cured rubbers made from vinylpyridine latices by means of ordi-nary vulcanizing formulas are characterized by greater strength and better resistance to wear and cold than those made from butadiene-styrene rubbers. Cured rubbers made from vinylpyridine latices in the presence of tetrachloroquinone have valuable special properties: resistance to oil, solvents, and synthetic greases at temperatures up to 200° C. Unlike cured rubbers made from butadiene-acrylonitrile raw rubbers, these properties of the cured rubbers are combined with great cold resistance. A shortcoming that restricts the use of vinylpyridine latices is the tendency of rubber stocks based on them to scorch.
Vinylpyridine latices are produced in a number of countries: SKMVP (USSR), Bunatex VP (Federal Republic of Germany), and Philprene VP (USA). They are used in the production of tires and to make cold-resistant and oil-resistant sealing parts in aviation, motor transportation, and other branches of industry. Latex copolymers of butadiene and 2-vinylpyridine are used to impregnate tire cord.