Patent GB-936356-A (GB)
Title: Bowling pin
IPC: B29C44/16
Filed: 1961-05-23
Abstract: Bowling pins of cellular plastic or elastomeric material are given an outer protective covering, e.g. a four coat system consisting of (1) an epoxy resin priming coat, (2) a modified nitrocellulose sealing coat, (3) an ethyl cellulose protective coating and (4) a top coat of modified nitrocellulose.  The coatings may be applied by conventional techniques.ALSO:A bowling pin is made of a foamed synthetic resinous cellular composition having an average expanded weight of from about 20 to 45 pounds per cubic foot.  In preferred embodiments (1) the pin has a synthetic resinous non-cellular shell and (2) the pore size of the cellular structure uniformly decreases as the distance from the centre of the pin increases.  The bowling pin may be made by expanding an expandable resin composition in an appropriately shaped mould, or in the recess of a non-cellular shell introduced first into the mould, e.g. by blow moulding, casting, centrifugal casting, injection moulding, compression or transfer moulding, hot moulding or extrusion moulding techniques.  The she may be slightly undersize before expansion of the core inside it. Alternatively the cellular component may be pre-formed before placing in the non-cellular shell, or the shell may be coated on to or cast in a mould round the pre-formed cellular component. The pin may contain a reinforcing rod, which may be of fibreglass, wood, metal, nylon, polymerized formaldehyde resin or cellulose acetate butyrate.  The cellular component may be polyurethane; polyvinyl chloride, e.g. a plastisol containing a blowing agent, copolymers of polyvinyl chloride, with vinylidene chloride and vinyl acetate, and mixtures thereof with butadiene-acrylonitrile copolymer; polystyrene, polymethylstyrene, styrene-butadiene-acrylonitrile or styrene-acrylonitrile copolymers; phenol-aldehyde resins including those cellular structures made by binding hollow phenolic spheres together with an epoxy, polyester or phenolic resin; rubber; epoxy, resins, e.g. esters containing epoxy groups and condensation products of epichlorohydrin and bis-phenol; polyesters; cellulose acetate; or polyethylene or polypropylene-each expanded in such a manner as is most suitable for the resin in question.  Suitable materials for the outer shell are polyethylene, polypropylene, nylon, epoxy resin, polyurethane, ethylcellulose, polyformaldehyde, cellulose acetate or propionate, copolymers of ethylene or propylene with butene, or a terpolymer of ethylene, butylene and acrylonitrile.  When no outer shell is used the cellular pin may be coated with (1) an epoxy resin primer, (2) a modified nitrocellulose sealing coat, (3) an ethyl cellulose protection coat and (4) a top coat of nitrocellulose.  The base of the pin may be reinforced with nylon or cellulose acetate butyrate, e.g. as described in U.S.A.  Specification 1,585,123.  A hollow or partially hollow cylindrical plastic cap may be inserted into the top of the pin.  A number of specific examples are given of the manufacture of bowling pins.  In one case a plasticizer (didecyl phthalate) is added to the foaming mixture to modify the elastic properties of the finished pin.  U.S.A.  Specifications 2,357,458, 2,578,911 and 2,681,321 also are referred to.ALSO:A bowling pin is made of a foamed synthetic resinous cellular composition having an average expanded weight of from about 20 to 45 pounds per cubic foot.  In preferred embodiments (1) the pin has a synthetic resinous non-cellular shell and (2) by using an excess of the composition to be expanded, the pore size of the cellular structure uniformly decreases as the distance from the centre of the pin increases.  The bowling pin may be made by expanding an expandable resin composition in an appropriately sloped mould, or in the recess of a non-cellular shell introduced first into the mould, e.g. by blow moulding, casting, centrifugal casting, injection moulding, compression or transfer moulding, hot moulding or extrusion moulding techniques.  The shell may be slightly undersize before expansion of the core inside it. Alternatively the cellular component may be preformed before placing in the non-cellular shell, or the shell may be coated on to or cast in a mould round the pre-formed cellular component. The pin may contain a reinforcing rod, which may be of fibreglass, wood, metal, nylon, polymerized formaldhyde resin or cellulose acetate butyrate. The cellular component may be polyurethane; polyvinyl chloride, e.g. a plastisol containing a blowing agent, copolymers of polyvinyl chloride with vinylidene chloride and vinyl acetate and mixtures thereof with butadiene-acrylonitrile p  copolymers; polystyrene, polymethylstyrene, styrene-butadieneacrylonitrile or styrene-acrylonitrile copolymers; phenol-aldehyde resins including those cellular structures made by binding hollow phenolic spheres together with an epoxy, polyester or phenolic resin; rubber; epoxy resins, e.g. esters containing epoxy groups and condensation products of epichlorohydrin and bis-phenol; polyesters; cellulose acetate; or polyethylene or polypropylene-each expanded in such a manner as is most suitable for the resin in question.  Suitable materials for the outer shell or polyethylene, polypropylene, nylon, epoxy resin, polyurethane, ethylcellulose, polyformaldehyde, cellular acetate or popionate, copolymers of ethylene or propylene with butene, or a terpolymer of ethylene butylene and acrylonitrile. When no outer shell is used the cellular pin may be coated with (1) an epoxy resin primer (2) a modified nitrocellular sealing coat (3) an ethyl cellular protective coat and (4) a top coat of nitrocellular.  The base of the pin may be reinforced with nylon or cellular acetate butyrate, e.g. as described in U.S.A. Specification 1,585,123.  A hollow or partially hollow cylindrical plastic cap may be inserted into the top of the pin.  A number of specific examples are given of the manufacture of bowling pins. In one case a plasticiser (didecyl phthalate) is added to the foaming mixture to modify the elastic properties of the finished pin.  U.S.A. Specifications 2,357,458, 2,578,911 and 2,681,321 also are referred to.