초록 ▼

A method for molding composite structural plastic components is disclosed wherein such components are cast from a polymerizable thermoset or thermoplastic composition in a conventional metalcasting mold. In the instant invention, a low viscosity thermoset or thermoplastic composition having reinforc

A method for molding composite structural plastic components is disclosed wherein such components are cast from a polymerizable thermoset or thermoplastic composition in a conventional metalcasting mold. In the instant invention, a low viscosity thermoset or thermoplastic composition having reinforcing fibers distributed therein is poured into conventional metalcasting molds, obviating the need for high heats and pressures associated with injection or compression molding of composite materials as taught in the prior art. In the case of a thermoset resin, the object to be fabricated is fully cured by the action of a catalyst at relatively low exothermic resin temperatures. In the case of a thermoplastic resin, curing is generally achieved independently of high added heat and pressure. If using a thermoplastic such as nylon 6 in the present invention, a preferred method of use involves the addition and combination of fiber reinforcements while the nylon 6 resin is being manufactured. The process for manufacturing nylon 6 involves three components: a monomer (i.e. caprolactam), an activator and a catalyst. The typical activator is HDI-caprolactame pre-polymer and caprolactam, and the typical catalyst is aliphatic cyclic amide, sodium salt. Typical activator and catalyst ratios are 0.50-3% by weight. Components used in the production of thermoplastic resins are often available in a solid form which must be liquefied so as to be suitable for pouring into a mold. One method of liquefying solid forms of caprolactam requires melting of the monomer into a liquid and then using a catalyst and activator to complete chemical transition into a flowable thermoplastic resin and ultimately a solidified part. The catalyst and activator complete the cure into a solid nylon 6 part without the need for high added heat or injection pressures. Caprolactam monomer is also available in a molten form and nylon casting activators can be acquired in liquid form, showing similar performance in the casting process and in the finished parts. However, all three components (monomer, activator and catalyst) are usually manufactured in a solid flake form. Whether thermoset or thermoplastic, the selected resin has a sufficiently low viscosity so as to allow mixture of the resin with high percentages of reinforcement fibers and suspension of the reinforcement fibers therein. During mixing and curing, the resin's viscid state prevents the fibers from settling or grouping, thereby achieving desirable dispersion of the fibers therein. This method furthermore enables fabrication of high quality composite structural plastics in traditional soft molds and molds produced using rapid prototyping techniques. The mold itself may be made by constructing a pattern of the object to be molded and casting the mold in a liquid or soft formable material such as wax, plastic rubber or spray metal which may use extractable cores therein. Structural plastic molds made with this process can be used for prototype or production purposes. This economical molding technique permits production of quality structural molds and plastics utilizing low cost molds heretofore used only in the prototyping of plastic visual aids.

대표청구항 ▼

1. A method of fabricating at least one composite structural plastic component from a flowable polymerizable composition, comprising the steps of:a.) providing a mold selected from a group of molds used alternatively in a process for casting structural metal objects from molten metal poured therein;

1. A method of fabricating at least one composite structural plastic component from a flowable polymerizable composition, comprising the steps of:a.) providing a mold selected from a group of molds used alternatively in a process for casting structural metal objects from molten metal poured therein; b.) selecting a flowable polymerizable composition; c.) combining said flowable composition with a plurality of short reinforcement fibers into a flowable mixture; d.) de-aerating said mixture for a time sufficient to lower viscosity of said composition so as to simultaneously retain pourability of said mixture and sufficiently cure and suspend said fibers in said composition; e.) pouring said mixture into said mold; f.) curing said composition so as to form a composite structural plastic component thereby; and g.) removing said component from said mold.