Patent GB-1191904-A (GB)
Title: A Process and an Apparatus for Flocking Articles
Inventor: BERNDT GERHARD
IPC: B05C19/00
Filed: 1967-05-24
Abstract: 1,191,904. Flocking; coating apparatus. FARBENFABRIKEN BAYER A.G. 24 May, 1967 [22 Sept., 1966], No. 24141/67. Headings B2E and B2L. [Also in Division D1] Flocked objects are produced by coating with a plastic or liquid adhesive composition including a solvent, removing most of the solvent to leave a layer of adhesive which is almost non-tacky but just sufficiently tacky for flocks to adhere thereto, flocking and then reducing the viscosity of the adhesive, and hardening the adhesive, the object being vibrated whilst it is being flocked and/or subsequently. If a thermoplastic adhesive is used the various changes in the viscosity of the layer of adhesive are brought about by heating apart from the hardening step. When dispersion or solution adhesives are used the state of reduced viscosity is obtained by applying solvents, and solidification is brought about by drying. The adhesive may be a cross linking adhesive e.g. a mixture of a pre-cross linked low molecular weight polyester, a precross-linked high molecular weight polyester in solution in ethyl acetate, and an aromatic polyisocyanate containing urethane groups. The low molecular weight polyester may be a hydroxyl polyester modified by urethane groups, such as that obtained from an adipic acid/diethylene glycol polyester cross linked with trimethylol propane, by reaction with modified tolylene diisocyanate. A suitable high molecular weight polyester is a condensation product of a glycol/adipic acid polyester, which may contain some hydroxyl groups, with tolylene diisocyanate. A suitable aromatic isocyanate is tolylene diisocyanate modified with trimethylol propane and butane diol. A web of material 2 from a supply roll 1 is led over an applicator roll 3 and during its subsequent treatment is supported on guide rollers 13. A coating knife 5 for applying a layer 6 of adhesive is provided with an earth connection 4, and is arranged above the applicator roll 3, and is followed by the drier 7. A first flocking unit 8 comprises a flock distributor 9 incorporating a brush roller 10 beneath which is arranged a grid electrode 11 connected to a high-voltage source 12 one terminal of which is earthed. A vibration mechanism 15 consisting of rotating hexagonal rods 14 is arranged beneath the web 2 below the flocking unit 8. A second flocking unit 8' with flock distributor 9', brush roller 10' and grid electrode 11', and a second vibration mechanism 15' are identical to the first. A solvent applicator 16 is arranged above the web 2 whilst a heater 17 combined with a vibration mechanism 15" is provided beneath the web 2. Beyond the heater 17 there is another vibration mechanism 15"'. The flocks can be aligned by the field applied to an auxiliary electrode 18. A drier 19 is used to solidify the adhesive and where this treatment comprises heat-treatment a cooling unit 20 is provided after 19. The counter electrode for the flocking zone is provided by the layer of adhesive 6 which is electrically conductive and which is connected through the knife 5 provided with the earth terminal 4 to the earth pole of the high voltage source 12.