Laminated sealing sheet based on plasticised PVC - has inner PVC layer with higher plasticiser content acting as plasticiser reservoir

摘要

Laminated sealing sheet based on plasticised PVC (I) has at least 2 layers of (I) of different compsn. w.r.t. auxiliaries and additives and opt. reinforcing inserts. The novel feature is that there is an inner (I) layer between 2 outer (I) layers which has a plasticiser (II) content at least 5 wt. pts. higher than that of the outer layers and acts as (II) reservoir. The outer (I) layers have a PVC/(II) wt. ratio of 75:25 to 55:45 (70:30 to 60:40) and the inner layer a ratio of 55:45 to 40:60. The (II) used in the inner layer can migrate and pref. is di-2-ethylhexyl, diisononyl, diisodecyl, C7-C9, C9-C11 or C8-C10 alkyl phthalate, tri-2-ethylhexyl or 2-ethylhexyl diphenyl phosphate, di-2-ethylhexyl azelate or diisodecyl or di-2-ethylhexyl sebacate or combinations of these, opt. with other (II). The (II) used in the outer layers is di-2-ethyl, di-n-octyl, diisooctyl, diisononyl, diisodecyl, C7-C11 or C6-C10 n-alkyl phthalate, di-2-ethylhexyl sebacate, 2-ethylhexyl diphenyl phosphate, a phenol or cresol alkylsulphonate ester or combinations of these. The thickness ratio of one of the outer layers to the (II) reservoir layer is ca. 1:2. Reinforcing inserts are provided in the inner layer or between this and an outer layer. The laminate is protected from deterioration, e.g. embrittlement and shrinkage, due to (II) loss.