摘要:
A process for preparing polyurethane rigid foams from polyols and polyisocyanates as well as blowing agents and optionally foam auxiliary agents, characterized in that the polyurethane rigid foam is obtained by reactingA) a polyol component with on average at least 3 hydrogen atoms, containing1. 60 to 100% of polyethers and/or polyesters with at least 2 hydroxyl groups and a molecular weight of 250 to 1,500, which have a surface tension of 6 to 14 mN/m with respect to i-pentane and/or n-pentane as blowing agent,2. i-pentane and/or n-pentane as blowing agent,3. water and4. optionally auxiliary agents and additiveswithB) a polyisocyanate with an NCO-content of 20 to 48 wt. % which has a surface tension of 4.0 to 8 mN/m with respect to i-pentane or n-pentane as blowing agentis described.
摘要:
A process for the production of rigid polyurethane foams having low thermal conductivity is described. This process comprises reacting A) a polyol component comprising: (1) at least one polyester polyol having a molecular weight of from 100 to 30,000 g/mol and containing at least two isocyanate-reactive hydrogen atoms; (2) at least one polyether polyol having a molecular weight of from 150 to 12,500 g/mol and containing at least two isocyanate-reactive hydrogen atoms and at least one tertiary nitrogen atom, and being prepared from a starter compound comprising ammonia or a compound containing at least one primary, secondary or tertiary amino group; (3) at least one polyether polyol having a molecular weight of from 150 to 12,500 g/mol and containing at least two isocyanate-reactive hydrogen atoms, and being prepared from a starter compound comprising water or a polyhydric alcohol; (4) at least one catalyst; (5) water (6) at least one blowing agent; and, optionally (7) auxiliary substances and/or additives; with B) an organic polyisocyanate having an NCO group content of from 20 to 48% by weight. Cyclopentane blown rigid polyurethane foams which exhibit low thermal conductivity and the end-use of such foams as an interlayer in a process for the production of composite components and for filling cavities is also disclosed.
摘要:
A system and method for recording, storing, transferring and viewing trace data from a processor with an embedded trace macrocell. The system provides for compression of repetitive trace records using an algorithm which identifies compressible trace record streams, creates a highly compressed processed trace record stream and stores the processed trace record stream in trace RAM. Thereafter, the processed trace record stream may be transferred to a host computer, expanded and displayed or printed for analysis.
摘要:
A handset actuated signal intercept circuit is located in a telephone central office and connected to the tip and ring leads of a telephone subscriber line. The signal intercept is operated from central office subscriber line power, but draws so small a current that it is undetectable in normal telephone usage. When a subscriber handset is lifted, the signal intercept detects dial tone and initiates a timing interval of predetermined duration. If no dialing pulses or tones are detected during this interval, the central office channel and trunk which are seized by the initiation of dial tone, are then freed for use on other subscriber lines. Alternatively, if the subscriber line is not authorized for use with touch-tone equipment, the appearance of selected touchpad tones on the subscriber line during the predetermined interval following the initiation of dial tone will activate a gate, which produces an alternating current short across the tip and ring leads of the subscriber line, and prevents further touchpad tones from getting out from the subscriber line.