Vacuum forming

Abstract: A plastic mold assembly comprising a male and female section for casting soft contact lenses from a polymerizable feed material wherein compensation for polymerization shrinkage is attained and disengagement of the male and female mold sections is facilitated by providing one flexible and one rigid mold section. Good optical properties of the mold surfaces are obtained by forming the mold sections entirely from a thermoplastic material such as polystyrene that will not crystallize when cooled from a melt. In one embodiment a plurality of flexible male sections having convex molding surfaces and a plurality of rigid female sections having concave molding surfaces are supported on frames to attain an increased production rate of finished soft contact lenses.

Abstract: Injection molding of thin plates of micro sized features was studied in order to manufacture micro-fluidic devices for bioMEMS applications. Various types of mold inserts—CNC-machined steel, epoxy photoresist, and photolithography and electroplating produced nickel molds—were fabricated and tested in injection molding. The feature size covers a range of 5 microns to several hundred microns. Issues such as surface roughness and sidewall draft angle of the mold insert were considered. Two optically clear thermoplastics, PMMA and optical quality polycarbonate, were processed at different mold and melt temperatures, injection speeds, shot sizes, and holding pressures. It was found that the injection speed and mold temperature in injection molding greatly affect the replication accuracy of microstructures on the metal mold inserts. The UV-LIGA produced nickel mold with positive draft angles enabled successful demolding. Numerical simulation based on the 2D software C-MOLD was performed on two types of cavity fillings: the radial flow and the undirectional flow. The simulation and experimental data were compared, showing correct qualitative predictions but discrepancies in the flow front profile and filled depth.

Abstract: The present invention is directed to a composition comprising polystyrene or polypropylene with at least 0.05% (w/w) of an additive or wetting agent, the article of manufacture comprised thereof, such as a mold for making contact lenses and the mold assembly containing said mold, and the use of such mold so to minimize defects, such as holes, puddles, chips and tears in the lens.

Abstract: An edible, water-soluble, thermoplastic molding composition comprising a starch material, a neutral inorganic alkali salt of protein material, water, an edible plasticizer, an edible lubricant, and other additives. This composition shows excellent moldability and processability when subjected to various constomery dry processes for molding and processing customary plastics, such as compression molding, transfer molding, extrusion molding, blow molding, inflation molding, injection molding, vacuum forming, pressure forming, heat sealing, etc. Transparent or translucent shaped articles obtained from the above composition have unique properties such as gas impermeability, solubility in water, edibility, biodegradability, etc., and may be utilized with favorable results in various fields such as food industry, feedstuff industry, agriculture, fisheries, etc. The shaped articles, if necessary, can be allowed to have any balance between its water resistance and its water-solubility by ultraviolet irradiation or by the incorporation of a protein-coagulating agent.