Patent GB-1468471-A (GB)
Title: Latent adhesive pressure-sensitive correction materials and their production
IPC: C09J7/38
Filed: 1975-01-31
Abstract: 1468471 Coated products COLUMBIA RIBBON & CARBON MFG CO Inc 31 Jan 1975 [4 Feb 1974 22 Nov 1973] 4399/75 Heading B2E [Also in Divisions B6 and D2] A latent adhesive pressure-sensitive correction element comprises a flexible foundation having bonded thereto a latent adhesive layer comprising one or more soft, pressure-flowable adhesive resins constituting at least 10% of the layer by weight and, embedded in the layer, a particulate, inert, non-adhesive material in amount at least 5% of the total weight of the layer and particulate material, at least 10% of the weight of the particles being of a particle size greater than the thickness of the adhesive layer so that the particles project beyond the surface of the layer to provide a barrier stratum which is substantially non- adhesive to the touch, the pressure-flowable adhesive resin(s), at ambient temperature, being capable of flowing through the barrier stratum only under the effect of typing pressure to render the surface of the layer adhesive in the impressed areas and capable of bonding, under the said typing pressure, to an erroneous image present on a copy sheet and removing the image from the copy sheet, the latent adhesive layer having a greater bond strength to the flexible foundation than it has to said copy sheet. In an embodiment the flexible foundation has thereon a longitudinal strip as specified above and an adjacent strip of a pressuretransferable image composition, the image composition being pressure-transferable to a copy sheet at typing pressure. Such an element may be in the form of a split imaging ribbon half the width of which is coated with the special imaging composition and the other half is coated with a complementary latent adhesive composition adapted to remove images produced with the imaging composition from a copy sheet under the effect of typing pressure. The flexible foundation may be paper or plastics film and porous papers and treated papers such as glassine paper are preferred. Plastics films are preferable for some applications and suitable films are polyethylene terephthalate, polyethylene, polypropylene cellulose acetate and nylon. Preferred adhesives for the correction layer are elastomers such as polybutenes, polyisobutylenes, polyisoprenes, polyvinyl ethers, polybutadiene and rubbery copolymers of butadiene with acrylonitrile, styrene and other monomers, and rosin esters. An extender or diluent may be present such as polyolefins such as polyethylene, polypropylene, polystyrene, polyvinyl butyrate, nylon and acrylic polymers, and waxes such as carnauba. montan, microcrystalline paraffin wax and beeswax. Suitable particulate material for inclusion in the correction layer has a minimum particle size about three times the main thickness of the layer. The preferred materials are spheres of polymers having an average particle size of 4-25 microns, preferred materials are polyethylene and polytetrafluoroethylene. Other materials that are suitable are glass beads, silica spheres, hydrated amorphous silica particles, starch particles and clay particles.