Shuttlecocks

Abstract

Abstract 1441110 Shuttlecocks DUNLOP Ltd 6 Feb 1974 [24 Feb 1973] 9206/73 Heading A6S Shuttlecock striking-caps are made by moulding a semi-rigid polyurethane foam, the foam having an indentation hardness in the range 30 to 75 units (ASTM D 2240). The foam-forming reaction may be carried out in a single stage, the reaction mixture comprising a suitable polyol, a polyisocyanate, a crosslinking agent, a catalyst, and a blowing agent. The polyol may be a polyether polyol e.g. a polyoxyalkylene trio], of molecular weight not exceeding 6000, or a polyester polyol e.g. a partially crosslinked diethylene glycol adipate, of molecular weight not exceeding 3000, these polyols all possessing a high proportion of primary hydroxyl end groups. The polyisocyanate, used in 5% stoichiometric excess based on polyol, is preferably a liquid at temperatures above 20‹C and may be a suitably modified diphenyl, methane diisocyanate or tolylene diisocyanate. The crosslinker may be a diol e.g. butane-1, 4-diol, or a triol e.g. glycerol, whilst the catalyst may be tetraethylene diamine or triethylene diamine. The blowing agent may be water and, if desired, a polysiloxane-oxyalkylene block copolymer may be added as surfactant. Reaction temperature may 'be between 20 and 65‹C as appropriate, mouldings being removable after 5 minutes curing time. The mouldings do not shrink appreciably after 7 days at 50‹C. A "two-stage process" involving prepolymers may also be used.

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