Copolymers

39.05 - Polymers of vinyl acetate or of other vinyl esters, in primary forms; other vinyl polymers in primary forms. - Poly(viny1 acetate) : 3905.12 - - In aqueous dispersion 3905.19 3905.21 3905.29 3905.30 - - Other - Vinyl acetate copolymers : - - In aqueous dispersion - - Other - Poly(viny1alcohol), whether or not containing unhydrolysed acetate groups - Other : 3905.91 3905.99 - - Copolymers - - Other This heading covers all vinyl polymers other than those of heading 39.04. A vinyl polymer is one whose monomer has the formula ,where the C-X bond is neither a carbon-carbon bond nor a carbonhydrogen bond. Polyvinyl ketones, where the C-X bond is a carbon-carbon bond are, therefore, excluded (heading 39.11). H CH2=C, X / r Polymers of vinyl acetate or of other \-in 1esters, of which pol (vinyl acetate is by far the most important, are not suitable for the manu acture of articles as t ey are too so and elastic. They are generally used for the preparation of lacquers, paints, adhesives, finishing or impregnatin agents for textiles, etc. Soluhons and dispersions (emulsions and suspensions) of poly(viny acetate) are used, e.g., as adhesives. g ff Poly(viny1 alcohol) is usually prepared by the hydrolysis of poly(viny1 acetate). Poly(viny1 alcohol) is available in a number of grades depending upon the content of unhydrolysed vinyl acetate grou s. These are excellent emulsifiers and dispersing agents and are used as protective colloids, ad esives, binders and thickeners in aints, pharmaceuticals and cosmetics and in textiles. Fibres produced from poly(viny1 alcoho ) are suitable for making underwear, blankets, clothing, etc. K P R t' Polyvinyl acetals can be re ared by reacting pol (vinyl alcohol) with an aldehyde such as formaldehyde or butyralde y e, or by reacting poly($nyl acetate) with an aldehyde. Other vinyl polymers include polyvinyl ethers, poly(viny1 carbazole) and poly(viny1 pymolidone). For the classification of olymers (including copolymers), chemically modified polymers and polymer blends, see the eneral Explanatory Note to this Chapter. (2' -