Hot melt bonding process for e.g. bonding shoe soles - using isocyanate-contg. prepolymer(s) from di:isocyanate(s) and polyester-diol(s) based on dodecane:di:oic acid and diol(s)

摘要

Bonding surfaces with NCO gp-contg. prepolymers (I) based on polyester-diol(s) (II) and di-isocyanate(s) (III), comprises applying (I) as a hot melt adhesive to at least one of the bonding surfaces. Novelty is that (a) (II) are derived from dodecanedicarboxylic acid (IV) and even-numbered diol(s) with at least 6 C atoms, (b) (I) contains not above 1.8 wt.% NCO gps., (c) (I) has Mn at least 4500 and (d) (I) is applied by spin-spraying and the coated surface is then immediately brought into contact with the other surface to form the joint. Specifically (II) is derived from (IV) and hexane-1,6-diol and has mol.wt. 4000-7000, and (III) is diphenylmethyldiisocyanate; ratio (NCO gps.):(NCO-reactive gps.) in (I) = (2.1:1)-(1.4:1); (I) is applied by a spin-bonding process; a preheated, adhesive-free surface is brought into contact with the surface which is coated with adhesive, under pressure and possibly with shaping. USE/ADVANTAGE - The process is useful for bonding wood, glass, ceramics, leather or plastics, etc. in applications such as component assembly, bookbinding, etc.; due to its rapid crystallisation, resulting in a rapid build-up of strength, the adhesive system enables fast cycle times on conventional bookbinding machines, and enables the prodn. of flat laminates with high early strength properties (as required, e.g. for bonding shoe soles, furniture, etc.).