Vinyl! chloride polymerisation in aq. suspension - with addn. of water-soluble dispersant before and after start of conversion to give dense porous prod.

摘要

Prodn. of vinyl chloride homo-, co- or graft polymers contg. 50 - 100 wt.% vinyl chloride units is carried out in aq. suspension in the presence of oil-soluble catalyst(s), water-soluble dispersant(s) (I) and opt. additional non-water-soluble dispersant(s) (II) and/or other additives at 35-90 degrees C. The novel feature is that 12-50, pref. 15-35 wt.% of the total amt. of (I) is added before the start of polymerisation and the rest of (I) and opt. (II) is added after heating the charge to is not 35, pref. min is not 45 degrees C but before the conversion reaches 3, pref. 2%. (I) consists of partially acetylated PVA (IA) with 5-25 wt.% acetate gps., methylcellulose (IB) methylhydroxyethylcellulose (IC) methylhydroxypropylcellulose (ID) methylhydroxybutylcellulose (IE) and/or hydroxypropylcellulose (IF).