LOW-VISCOSITY HOT MELT ADHESIVE COMPOSITIONS Russian patent published in 2008 - IPC C09J153/02 C09J7/02 

FIELD: adhesives.

SUBSTANCE: invention relates to stable low-viscosity hot melt adhesive compositions, to special block copolymers used therein, and also to tapes and labels including said compositions. Objective of invention is to provide hot melt adhesive compositions having viscosity by 5% lower or higher than initial value when heated for 24 h at 177°C and having melt viscosity = 80 Pa·s at 177°C. Composition comprises: (a) at least one block copolymer containing at least two terminal polyvinyl-aromatic blocks and at least one core block composed of copolymerized isoprene/butadiene mixtures at weight ratio between 45:55 and 55:45 and having polyvinyl-aromatic content 17-20%, apparent common molecular mass 180000-190000, content of 1,2-vinyl bonds and/or 3,4-vinyl bonds not more than 15 wt% in conjugated diene blocks while bonding efficiency 63 to 80% at weight ratio 40-45% of the total mass of composition; (b) aliphatic/aromatic hydrocarbon resin increasing adhesiveness, containing less than 16 wt % of aromatic structure as measured by H-NMR method, having glass transition temperature (Tg) 30 to 55°C as measured by differential scanning calometry technique, and softening point (Ring & Ball) between 85 and 95°C at weight ratio 45-55% of the total mass of composition; and (c) plasticizer in amount 5-15% of the total mass of composition.

EFFECT: optimized physicochemical characteristics.

3 cl, 4 tbl, 2 ex