RUBBER FOR BABY BOTTLE NIPPLES, PACIFIERS, & SYRINGE PLUNGERS

摘要

The production of a protein free synthetic polyisoprene which has both low levels of chemical impurities and good physical properties has yet to be realized. It has now been envisioned that the use of neodymium catalyzed polyisoprene will offer the combined advantages of both a clean, as well as, high cis-1,4 polymer. Synthesis of polyisoprene rubber using a neodymium based catalyst system is described. Characterization of the material shows the absence of an ultra high molecular weight fraction and the presence of very high cis-1,4-microstructure. Gum stock and black filled compound studies comparing neodymium polyisoprene with natural rubber, titanium polyisoprene, and lithium polyisoprene have been performed. Results indicate that polyisoprene rubber synthesized using a neodymium catalyst system (Nd—PI) has similar stress-strain and tear properties as synthetic titanium polyisoprene. Analysis of residual volatile, extractable, and oligomer levels indicates Nd—PI is indeed a clean source of high cis synthetic polyisoprene.

主权项

1. A breast hood to be connected to a milk pump, said breast hood comprising a wall means forming an outer surface and an inner surface, said inner surface being substantially conical so as to have a wide opening end for engaging a female breast, and a small opening end, said outer surface being of a first, relative rigid material, while said inner surface is comprised of polyisoprene rubber made with a neodymium catalyst, wherein the polyisoprene rubber is made by a process which comprises polymerizing isoprene monomer in the presence of a neodymium catalyst system and terminating the polymerization with an alkaline aqueous neutralizer solution, wherein the neodymium catalyst system is prepared by (1) reacting a neodymium carboxylate with an organoaluminum compound in the presence of isoprene for a period of about 1 minutes to about 12 hours to produce neodymium-aluminum catalyst component, and (2) subsequently reacting the neodymium-aluminum catalyst component with a dialkyl aluminum chloride for a period of at least 30 minutes to produce the neodymium catalyst system, wherein the dialkyl aluminum chloride is added to the neodymium-aluminum catalyst component over a period of at least 30 minutes.