Buoys – rafts – and aquatic devices – Water skimming or walking device – Surfboard
Patent
1985-04-12
1987-12-15
Peters, Jr., Joseph F.
Buoys, rafts, and aquatic devices
Water skimming or walking device
Surfboard
264 464, A63C 1505
Patent
active
047130326
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a method of making sailboards or surfboards as well as to a sailboard or surfboard.
In a known method of this kind, a prefabricated EPS foam core has a glass fibre mat wound around it, is inserted in the mold and has epoxy resin painted or poured on it. Thereafter, the mold is closed so that the epoxy resin cures and, with the glass fiber mat, forms an impact resistant laminate. After removing the laminate from the mold, it is provided with a fine or gel layer which may, however, also be introduced in the mold already before the wound EPS foam core is inserted. This so-called epoxy technology permits laminates of high strength, low weight and good appearance to be produced.
Disadvantages with this known method are the high costs of the epoxy foam, the health hazard when processing same, and the relatively long cycle necessitated by the curing period for the epoxy foam and amounting to about 30 minutes.
The invention is based on the problem of improving a method according to the classifying portion of claim 1 so that laminates can be produced at lower costs and less health hazard with at least the same weight and strength as laminates made by the epoxy technique. It is also a problem of the invention to improve a sailboard or surfboard portion of claim 18 so that it has a low weight, high strength and low cost to produce.
To solve this problem, a method and a sailboard or surfboard of the aforementioned kind are suggested with the features of the invention mentioned in the characterising portion of the claims.
Surprisingly, it has been found that polyurethane resin that had hitherto been exclusively used as polyurethane foam for the cores of sailboards will, in conjunction with fibrous material and a suitable surface layer, result in a laminate which is very impact resistant and gives the board a high strength at a low weight. Polyurethane resin is much cheaper than epoxy resin and cures much more rapidly so that the lower cost of material and the shorter cycle periods give an overall cheaper production. In addition, its processing has fewer health hazards.
The polyurethane resin is preferably set by a reaction retarder so that there is a delay of several minutes, particularly about 10 minutes, in the chemical reaction of its components. There is then sufficient time to pour the resin onto the fiber-reinforced foam core and then insert the core in the mold and close the mold. If, in accordance with a development of the invention, the mold is then held at a temperature of about 80.degree. C. during curing of the shell laminate, one obtains a curing time of about 5 minutes. When compared with a curing time of about 30 minutes required for epoxy resin, it will become evident that the production capacity per set of tools when using the method of the invention is considerably higher. One can expect 5 times the production capacity.
Preferably, the polyurethane resin is given a low foamability so that, despite the inevitable production tolerances for the prefabricated foam core, sufficient pressure is built up in the entire shell laminate zone and any isolated departures of the foam core surface from the desired measurements will be balanced out by thickness fluctuations in the shell laminate.
The surface layer may be a gel coating with which the mold is lined before insertion of the foam core covered with saturated fibrous material, as is known per se in epoxy technology.
According to a special embodiment of the invention, the surface layer is a film of thermoplastic material with which the mold is lined before insertion of the foam core reinforced with saturated fibrous material. With a thermoplastic film as surface layer, especially the impact strength of the shell increases. In addition, introduction of a thermoplastic film in the mould is easier from a production point of view than lining the mold with a gel coating because one can dispense with treating the mold wall with a parting compound and polishing it before introducing the surface layer.
Preferably, the film is introduced in t
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Peters Jr. Joseph F.
Salmon Paul E.
TAA Technique and Administration AG
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