Patent GB-770454-A (GB)
Title: Improvements in or relating to thermoplastic adhesives
IPC: C09J7/35
Filed: 1954-05-28
Abstract: A thermoplastic adhesive characterized by non-tackiness at room temperature and by the property of becoming tacky upon heating to a predetermined temperature higher than room temperature and remaining tacky for a substantial time interval following subsequent cooling to substantially room temperature, and which comprises as the essential constituents thereof a major proportion of a thermoplastic resin and a specific thermoplastic plasticizer both having softening points higher than room temperature and at least one of the softening points being lower than the boiling point of water, is produced by forming a hot melt comprising at least the essential constituent of the composition having the softening point lower than the boiling point of water, adding to the melt an aqueous dispersion of a rubbery material not readily soluble or otherwise incorporable from a dry state in the melt, heating the melt to a temperature sufficient to boil away the aqueous carrier from the dispersion while mixing the melt to effect thorough dispersion therein irrespective of the degree of compatibility of the rubbery material in the melt, adding to the melt any of the essential constituents thereof not already present, while maintaining the temperature of the melt above the softening point of all constituents thereof, thereafter cooling the melt to a temperature below the softening point of the plasticizer, and effecting rapid setting of the melt to solid and non-tacky consistency by mixing therewith a small quantity of the same specific plasticizer in finely-divided solid form.  The final melt may be applied as a film on a supporting surface, followed by cooling and rapid setting as above.  The thermoplastic resin may be a coumarone-indene resin and the plasticizer may be diphenyl phthalate, Ncyclohexyl paratoluene sulphonamide, tri-(ptert. butyl phenyl) phosphate, or pentaerythritol ester of rosin.  The rubbery material may be butadiene-styrene copolymer, or a nitryl-styrene acrylonitrile copolymer.  Compositions described include also polystyrene. Specifications 711,465 and 757,551, [Group VIII], are referred to.ALSO:A thermoplastic adhesive characterized by non-tackiness at room temperature and by the property of becoming tacky upon heating to a predetermined temperature higher than room temperature and remaining tacky for a substantial time interval following subsequent cooling to substantially room temperature, and which comprises essentially a major proportion of a thermoplastic resin and a specific thermoplastic plasticizer both having softening points higher than room temperature and at least one of the softening points being lower than the boiling point of water, is produced by forming a hot melt comprising at least the essential constituent of the composition having the softening point lower than the boiling point of water, adding to the melt an aqueous dispersion of a natural rubber, heating the melt to a temperature sufficient to boil away the aqueous carrier from the dispersion while mixing the melt to effect thorough dispersion therein irrespective of the degree of compatibility of the rubber in the melt, adding to the melt any of the essential constituents thereof not already present, while maintaining the temperature of the melt above the softening point of all constituents thereof, thereafter cooling the melt to a temperature below the softening point of the plasticizer, and effecting rapid setting of the melt to solid and non-tacky consistency by mixing therewith a small quantity of the same specific plasticizer in finely divided solid form.  The final melt may be applied as a film on a supporting surface, followed by cooling and rapid setting as above.  The thermoplastic resin may be a coumarone-indene resin and the plasticizer may be diphenyl phthalate, N-cyclohexyl paratoluene sulphonamide, tri (p-tertbutyl phenyl) phosphate or pentaerythrital ester of resin. Specifications 711,465 and 757,551 [both in Group VIII] are referred to.