Patent GB-762933-A (GB)
Title: Platform sole shoe and method of making such shoe
IPC: A43B13/28
Filed: 1954-11-26
Abstract: 762,933. Moulding shoe sole rubber compositions. MISHAWAKA RUBBER & WOOLLEN MANUFACTURING CO. Nov. 26, 1954 [March 16, 1954], No. 34391/54. Classes 70 and 87(2). [Also in Group VII] Moulding shoe soles. A pre-moulded outersole and foxing unit 20, Figs. 2, 6 has a cavity 21 therein to receive, for adhesive attachment thereto, a platform layer 16 which forms part of a lasted shoe upper component of which an upper 10 which may be of leather, also forms part. The unit 20 may be formed by slosh moulding from rubber or rubbery material, which solidifies and cures on the application of heat, to form a layer of varying thickness on the walls of a mould 26 as shown in Fig. 4. The unit 20 may be applied to the assembled shoe upper, as shown in Fig. 6, by the aid of a flared slip ring 25 to spread the foxing 23 and hold the cemented surfaces apart until the parts are properly centred, after which the ring is removed and the parts pressed and rolled into intimate adhesion, when the completed shoe is removed from the mould. This latter may be of aluminium or other metal of high heat conductivity prepared from a completed shoe or a model of each shoe made for example, of rubbery material, high melt wax, low melt metal, plaster of Paris &c. by casting, spraying or electro-deposition. The models may be used for making other moulds by preparing negatives therefrom. Rubber compositions. Fluid plastisol dispersions made from polyvinyl chloride resins of the type sold under the Registered Trade Mark " Geon " and " Vinylite," also Registered Trade Mark, are suitable for making the tmit 20. A suitable dispersion is given as: -Dioctyl phthalate 45 parts as plasticizer ; titanium oxide pigment 10 and dioctyl phthalate 30 parts as pigment dispersion, dibasic lead phosphite 3 parts as stabiliser, and " Geon " 121 Polyvinyl chloride 100 parts as resin. Other suitable plasticizers are tricresyl phosphate, trioctyl phosphate, dioctyl adipate, dioctyl sebacate, polydi-2-ethylhexyl azelate, diethylene glycol and tributoxyethyl phosphate. The mould is first heated to a uniform temperature of about 250‹F. and the plastisol is allowed to stand in contact with the mould walls for about 105 seconds during which time a layer forms on the interior walls of the mould the thickness of which depends on the portion of the wall on which it is formed. Excess plastisol is then poured off and allowed to drain and the mould reheated to about 350‹F. to set and cure the remaining plastisol. The unit is stripped from the mould after it has cooled below 150‹F. and its edges trimmed off, ready for adhesive attachment to the upper component. Suitable cements for the purpose may be prepared from butadiene acrylonitrile copolymers containing 25-40 per cent acrylonitrile, such as " Hycar " (Registered Trade Mark) OR-15 or Paracril (Registered Trade Mark) C. A mill mixed cement may comprise Ground " Paracril " C, 100 parts, antioxidant BLE powder 1 part, extra light calcined magnesium oxide 5 parts, zinc oxide 9 parts, stearic acid 0À3 parts, silene EF calcium silicate 24 parts, pigment 5-10 parts and sulphur 3 parts. A churn mixed cement may comprise in addition to the stock just mentioned 36 parts of rubber chloride and 427 parts of methyl ethyl ketone. 4 parts of " Butyl Eight " dithiocarbamate accelerator as added. Zinc dibutyl dithiocarbamate and zinc ethyl dithiocarbamate accelerators may also be used.