摘要:
A method for preparing a flexible or semi-flexible polyurethane foam by reacting an organic polyisocyanate with a polyol in the presence of urethane catalyst, water as a blowing agent, optionally a silicone surfactant, and a cell opening additive characterized in that the cell opening additive comprises an aqueous dispersion of particles comprising a wax substance and optionally an emulsifier, at least 35% of the particles having a size of 0.2 to 5 microns and a melting point which ranges from 0 to 55.degree. C. below the maximum foam exotherm temperature.
摘要:
A method for preparing a polyurethane flexible molded by reacting an organic polyisocyanate with a polyol in the presence of urethane catalyst, water as a blowing agent, optionally a cell opener, and a silicone surfactant cell stabilizer having the formula: Me3Si(OSiMe2)x(OSiMeG)yOSiMe3 wherein x has an average value from 1 to 4.5 and y has an average value from 0.75 to 7.5, the value of x/y is from 0.25 to 5 and the value of x+y is from greater than 5 to 9, G is a group having the formula —D(OR″)mA where D is a divalent organic linking radical, R″ is an alkylene group, m has an average value from 1 to 5, and A denotes an —OR′″ or an —OOCR′″ group, where R′″ is selected from the group consisting of methyl, ethyl, and a combination of methyl and ethyl.
摘要:
A method for preparing a polyurethane flexible foam which comprises reacting an organic polyisocyanate with a polyol in the presence of urethane catalyst, water as a blowing agent, optionally a cell opener, and a polydimethylsiloxane cell stabilizer composition which comprises at least 90 wt % of polydimethylsiloxane molecules having the formula: Me3Si(OSiMe2)nOSiMe3 where n is 5 to 7, provided at least 15 wt % of each of the three molecules in which n is 5, 6 and 7 is present.
摘要:
A method for preparing a polyurethane flexible molded by reacting an organic polyisocyanate with a polyol in the presence of urethane catalyst, water as a blowing agent, optionally a cell opener, and a silicone surfactant cell stabilizer having the formula: Me3Si(OSiMe2)x(OSiMeG)yOSiMe3 wherein G is a group having the formula —D(OR″)mA where D is a divalent organic linking radical, R″ is an alkylene group, m has an average value from 1 to 5, A denotes an —OR′″ or an —OOCR′″ group, where R′″ is selected from the group consisting of methyl, ethyl, and a combination of methyl and ethyl, x has an average value from 1 to 3 and y has an average value from 0.25 to 1, the value of x/y is from 2.5 to 5 and the value of x+y is from 1.5 to 3.5.
摘要:
A method and an apparatus or machining a workpiece include the use of a cryogenically cooled oxide containing ceramic cutting tool. The method involves cryogenic cooling of the cutting tool during a cutting operation, which cooling results in enhanced wear resistance and fracture resistance of the cutting tool. A preferred embodiment involves jetting a cryogenic fluid directly at the cutting tool.
摘要:
A process is set forth for cold rolling of a metal strip, wherein the metal strip passes through a nip between two counter-rotating rolls, driven in counter-rotation substantially at room temperature, wherein a cold and/or liquefied gas, preferably an inert gas, is blown into the area of the nip or roll gap. A roll stand according to the present invention comprises two counter-rotating rolls forming a nip or rolling gap and nozzle means for blowing a cold and/or liquefied gas, preferably an inert gas, through at least one orifice of said nozzle means into the area of the roll nip. Preferably, the temperature of the cold and/or liquefied gas is appreciably lower than room temperature.
摘要:
A method for preparing a polyurethane flexible molded or rigid foam by reacting an organic polyisocyanate with a polyol in the presence of urethane catalyst, water as a blowing agent, optionally a silicone surfactant cell stabilizer, and a cell opener characterized in that the cell opener comprises the reaction product of 1,1,1,3,5,5,5-hepta(hydrocarbyl)-trisiloxane coupled with polyalkyleneoxide mono allyl ether and capped with a C1-C20 hydrocarbyl group-containing succinic anhydride.
摘要:
An apparatus and a method are disclosed for reducing a thickness of a thermomechanically-affected layer on an as-machined surface of a hard metal workpiece being machined by a hard cutting tool exerting a thermomechanical load on a surface of the workpiece. The method involves reducing the thermomechanical load on the surface of the workpiece, and the apparatus includes a means for reducing the thermomechanical load on the surface of the workpiece.
摘要:
A method and apparatus are set forth for transferring a cryogenic fluid. A polymeric, coaxial (i.e. “tube-in-tube” geometry) transfer line is utilized where a first portion of the cryogenic fluid flows through the inner tube while a second portion flows through an annulus between the inner tube and outer tube which annulus is at a lower pressure than the inside tube. In one embodiment, the inner tube is substantially non-porous and the transfer line is preceded by a flow control means to distribute at least part of the first and second portions of the cryogenic fluid to the inner tube and annulus respectively. In a second embodiment, the inner tube is porous with respect to both gas permeation and liquid permeation such that both a gaseous part and a liquid part of the first portion permeates into the annulus to form at least a part of the second portion.
摘要:
A cryogenic fluid jet is used in an apparatus and a method for remote cooling of a cutting tool engaged in machining a workpiece under high-energy conditions, such as high-speed machining, hard-turning, cutting of difficult to machine materials, and combinations thereof. The apparatus and method use a stabilized, free-expanding cryogenic fluid jet having a pulse cycle time less than or equal to about 10 seconds. The apparatus and method increase the cleanliness of machined parts and chips and machining productivity of hard but brittle tools, including but not limited to tools which should not be cooled with conventional cooling fluids.