摘要:
The present invention is directed to polyurethane moldings produced via the RIM process. These polyurethane moldings have excellent reactivity, demold properties (at a 30s demold), and good elongation and tear strength, and comprise the reaction product of an HDI prepolymer having an NCO content of 5 to 25%, a functionality of less than 2.3, and a monomer content of less than 10%, with an isocyanate-reactive component comprising b1) at least one relatively high molecular weight organic compound containing at least about two isocyanate-reactive hydroxyl groups; b2) at least one relatively low molecular weight organic compound selected from the group consisting of diols, aminoalcohols, and mixtures thereof; and b3) at least one relatively low molecular weight hydroxyl-based crosslinking compound containing no more than one aliphatic amine hydrogen atoms capable of reacting with isocyanate groups; in the presence of at least one catalyst.
摘要:
Low friction or nearly frictionless compasses are provided. One compass embodiment includes a housing having a wall forming a chamber, the housing having a closed end and an open end. The compass includes a fluid disposed within the chamber. The compass includes a magnetized material floating in the fluid, wherein the magnetized material is operative to indicate Earth's magnetic north. The compass includes a protective face adjacent to the open end, wherein the protective face closes the open end of the chamber. Also provided is a compass that includes low friction material deposited on at least one side of the magnetized material and the adjacent closed end of the housing to create a nearly frictionless interface.
摘要:
An apparatus and method are disclosed for compensating for string tension acting upon the body of an acoustic instrument. An acoustic instrument incorporating the string tension compensating apparatus is also disclosed.
摘要:
The invention is directed to a process for preparing a Class-A surface, fiber reinforced molded article. The process broadly requires the use of two separate fiber surfacing veils with a fiber reinforcement sandwiched therebetween. A polyurethane reaction system is injected into the mold. The system requires the presence of specified hindered amines.
摘要:
An apparatus and method are disclosed for artificially aging a musical instrument is provided. The apparatus and method include oscillating the sound board of the instrument by an energy source at specific frequencies over the playing frequency range of the instrument.
摘要:
The present invention relates to a free-flowing, dry, granular powder comprising the reaction product of 4,4'-diphenylmethane diisocyanate and resorcinol, the product having an isocyanate group content of from 27 to 31% by weight, and to the process for manufacture thereof.
摘要:
The present invention is directed to a process for the production of optionally cellular, polyurea elastomer moldings by reacting a reaction mixture containing(I) a polyisocyanate,(II) a polyether having at least two isocyanate-reactive groups and a molecular weight of 1800 to 12,000 in which at least 50% of the isocyanate-reactive groups are primary and/or secondary amino groups,(III) about 5 to 50% by weight, based on the weight of component (II) of a chain extender comprising a sterically hindered aromatic diamine and(IV) about 1 to 20% by weight, based on the weight of components (II) and (III) of an active hydrogen-containing fatty acid ester having a molecular weight of about 500 to 5000 and prepared by reacting an alcohol with an aliphatic, saturated or unsaturated fatty acid, said ester being characterized in that at least one aliphatic acid which contains more than eight carbon atoms is built into the molelcule, said ester further characterized as having an acid number of 0 to 100 and a hydroxyl number of 0 to 150 with at least one of said numbers being greater than 0,wherein the fatty acid ester is initially blended with component (II), component (III) or a mixture thereof and the reaction mixture is processed as a one-shot system by the RIM process at an isocyanate index of about 70 to 130.The present invention is also directed to an isocyanate-reactive component for use in a RIM process based on components (II), (III) and (IV).
摘要:
A device for accelerating ions between a potential towards a central point in space is disclosed. The device can be used to accelerate ions along a collision path with other accelerated ions or other present particles resulting in a nuclear fusion reaction. The device improves upon the prior art by using a plasma as one of the electrodes forming the potential.
摘要:
In accordance with the invention, a reinforcing agent is added to the polyol side before the Reaction Injection Molding (RIM) process. The agent of the invention comprise particulate flakes which are characterized by their fine particle size and high aspect ratio. It was surprisingly found that the incorporation of the agent of the invention in the RIM process yields molded parts with a good combination of properties including flexural and tensile modulus heat sag and reduction in the coefficient of linear thermal expansion and high Distinctness Of Image (DOI) values.