| 摘要 |
A bowling pin 16 is moulded from an unsaturated cyclic acetal based A-stage thermosetting resin in which there is uniformly dispersed a quantity of weight-compensating particulate material. The thermosetting resin is preferably derived by heating in the presence of diethyl sulfate either the 3,9 dialkenylspirobi(meta-dioxane) or the 5-ethyl 5-hydroxymethyl 2-propenyl (meta-dioxane) type of monomer. The former type of monomer includes diallylidene pentaerythritol and dicrotonylidene pentaerythritol, whilst the latter type includes monocrotonylidene trimethylolpropene. The particulate filler material comprises minute hollow spheres of either phenolic resin or glass. The pin preferably comprises a shell 18 of the same thermosetting resin as the main pin form 16, reinforced with glass fibres and containing titanium dioxide.
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