摘要:
Silicon-containing peroxyester compounds, for example, represented by the following formula: ##STR1## useful as a polymerization initiator, which compounds can produce vinyl chloride polymers having a high quality in a high yield and in a short reaction time.
摘要:
Novel 1,1,2,2-tetramethylpropylperoxy esters are provided. They are useful as a polymerization initiator in polymerizing vinyl chloride, vinylidene chloride and vinyl acetate monomers, with the advantage of completing polymerization within a short time.
摘要:
A vinyl chloride polymer is prepared through suspension polymerization of a vinyl chloride monomer in the presence of a polymerization initiator in a reactor. The reactor is charged with up to 4/5 of the overall monomer charge to initiate polymerization. Polymerization is carried out under a certain saturated vapor pressure of P1 kgf/cm.sup.2 at a preset polymerization temperature. When the internal pressure of the reactor declines to P2 kgf/cm.sup.2, the remainder of the overall monomer charge is continuously fed to the reactor so as to maintain the internal pressure within the range of (P1-.DELTA.P) wherein .DELTA.P=P1-P2 ranges from 0.1 to 2.0 kgf/cm.sup.2. A vinyl chloride polymer having a high degree of polymerization is efficiently produced while alleviating the load of heat removal.
摘要:
A process for producing a vinyl chloride polymer is provided which includes the steps of: (A) suspension polymerizing vinyl chloride or a monomer mixture containing vinyl chloride, in an aqueous medium to obtain a polymer slurry; (B) stripping unreacted monomers remaining in the polymer slurry; and (C) subjecting the polymer slurry having passed through the step (B), to dehydration at a temperature of from 80° C. to 95° C., preferably within 60 minutes after the stripping. According to this process, the polymer cake obtained after the polymer slurry Is dehydrated can be made to have a greatly low water content. Hence the drying time in the drying step can be shortened to bring about an improvement in productivity and also to achieve a reduction of energy consumption in the drying step and consequently a reduction of production cost. Vinyl chloride polymer dried products having good anti-initial discoloration properties can be obtained.
摘要:
A process for producing a vinyl chloride polymer, including the steps of (a) subjecting a vinyl chloride monomer alone or a monomer mixture containing a vinyl chloride, to suspension polymerization in water; (b) subjecting the resultant vinyl chloride polymer slurry to stripping to remove an unreacted monomer remaining therein; and (c) dehydrating the polymer slurry having been subjected to stripping. In the polymerization step (a), the ratio of water/monomer is set in a weight ratio of from 0.80 to 1.50, and the viscosity at 20° C. of the polymer slurry to be fed to the stripping step is previously kept adjusted to 0.30 Pa·s or lower. In the stripping step (c), the residual unreacted monomer in the polymer slurry can efficiently be removed using steam in a smaller quantity, thus the vinyl chloride polymer can be produced at a high productivity.
摘要:
A process for regenerating unreacted vinyl chloride monomers is provided which has the step of compressing by means of an compressor an unreacted vinyl chloride monomer recovered from a process of vinyl chloride polymer production; compressing the same in contact with a lubricating oil fed into the compressor. In this process, the lubricating oil contains a polymerization inhibitor. Hence, even when this lubricating oil is circulated and reused as a lubricating oil after its separation from the unreacted vinyl chloride monomer, any vinyl chloride monomer remaining in the lubricating oil can effectively be kept from polymerizing in lubricating-oil circulation lines.
摘要:
A steel sheet for soft-nitriding has a composition containing: C: 0.05% or more to 0.10% or less; Si: 0.5% or less; Mn: 0.7% or more to 1.5% or less; P: 0.05% or less; S: 0.01% or less; Al: 0.01% or more to 0.06% or less; Cr: 0.5% or more to 1.5% or less; V: 0.03% or more to 0.30% or less; and N: 0.005% or less, on a mass percent basis, wherein a ratio of amount of solute V to the V content (amount of solute V/V content) is more than 0.50, and balance comprises Fe and incidental impurities, and a complex-phase microstructure containing ferrite and pearlite.
摘要:
A steel sheet for soft-nitriding has a composition containing: C: 0.05% or more to 0.10% or less; Si: 0.5% or less; Mn: 0.7% or more to 1.5% or less; P: 0.05% or less; S: 0.01% or less; Al: 0.01% or more to 0.06% or less; Cr: 0.5% or more to 1.5% or less; Nb: 0.005% or more to 0.025% or less; and N: 0.005% or less, on a mass percent basis, such that C and Nb satisfy 0.10≦Nb/C≦0.30 (where C and Nb are respective contents of the elements (by mass %)), wherein balance comprises Fe and incidental impurities, and a microstructure that is a complex-phase microstructure containing ferrite and pearlite, and the microstructure having a ratio of a microstructure other than the ferrite and the pearlite of 1% or less, and the microstructure having a ratio of polygonal ferrite in the ferrite of less than 50%.
摘要:
A vertical chain memory includes two-layer select transistors having first select transistors which are vertical transistors arranged in a matrix, and second select transistors which are vertical transistors formed on the respective first select transistors, and a plurality of memory cells connected in series on the two-layer select transistors. With this configuration, the adjacent select transistors are prevented from being selected by respective shared gates, the plurality of two-layer select transistors can be selected, independently, and a storage capacity of a non-volatile storage device is prevented from being reduced.
摘要:
A sample stage device (10) is so configured as to calculate ideal position information xtg(i), tg(i) per predetermined period that is unaffected by drive conditions relating to gaps (25, 26), etc., and to determine, per predetermined cycle and in real time, deviations dx(i), dy(i) between real-time measured positions x(i), y(i) by position detectors comprising laser interferometers (33, 34), etc., and ideal position information xtg(i), tg(i). In addition, it calculates, based on deviations dx(i), dy(i) thus determined, such speed command values vx(i), vy(i) for motors (27, 28) that measured values x(i), y(i) would follow ideal position information xtg(i), tg(i), and performs stable and high-speed positioning control for a sample table (11) through feedback control that controls speed in real time. Thus, with respect to a sample stage device, it is possible to provide a stable and high-speed positioning control method for a sample table, which is capable of suppressing noise caused by thermal drift and vibration, without being affected by drive conditions, such as the initial states of gaps, etc.