Master batch method

In the most common production method, the semibatch process, about 10% of the preemulsified monomer is added to the deionised water in the reactor. A shot of initiator is added to the reactor to create the seed. Some manufacturers use master batches of seed to avoid variation in this step. Having set the number of particles in the pot, the remaining monomer and, in some cases, additional initiator are added over time. Typical feed times ate 1—4 h. Lengthening the feeds tempers heat generation and provides for uniform comonomer sequence distributions (67). Sometimes skewed monomer feeds are used to offset differences in monomer reactivity ratios. In some cases a second monomer charge is made to produce core—shell latices. At the end of the process pH adjustments are often made. The product is then pumped to a prefilter tank, filtered, and pumped to a post-filter tank where additional processing can occur. When the feed rate of monomer during semibatch production is very low, the reactor is said to be monomer starved. Under these... 

The validation protocol should be prepared after the master batch record is approved and signed by responsible parties (i.e., the manufacturer and NDA or ANDA holder). The batch directions should be detailed and easily understood. For example, mixing speeds and times, mixer positions, and method of adding ingredients should be explained clearly. The protocol must agree in process descriptions and flowcharts and be specific enough to remove any ambiguities on process conditions, decisions, or product specifications. For these reasons, it is usually beneficial to prepare a production-sized, prevalidation batch with the proposed final batch record. This batch should also be completely tested and meet finished product specifications. 

Proper production process execution and performance of analytical procedures relies on comprehensive, clearly stated, and unambiguous documentation. This is necessary whether the document is used to initiate an activity (e.g., process, method, work instruction) or contains results that will be reviewed by someone else. A master batch record that can be easily misinterpreted by trained operators is a serious source of process variability. Similarly, if the analytical method is not written in a clear, concise, and sufficiently detailed manner, interpretation may be different from analyst to analyst, also resulting in higher than expected variability and perhaps an OOS result. Process and analytical documentation should be written with the user in mind and authored by individuals with intimate familiarity with the task to be carried out. The written procedures should be concise or crisp, yet contain sufficient technical detail to lead trained operators and analysts through the same set of operations with the outcome being the same when applied to the same material(s). 

According to a JSR patent Nd-catalysis allows for the polymerization of BD in the presence of carbon black. By this method a BR/carbon black master batch is obtained. The master batch technology eliminates time and energy consuming mixing of carbon black and rubber [340,341]. According to this patent the content of bound rubber (amount of rubber which can be extracted from a carbon black/rubber mixture with an appropriate solvent, e.g. toluene) is increased and vulcanizate properties are improved. 

Adams and Baker illustrate a method for determining the carbon black concentration of the master batch, and also the per cent of the master batch that must be added to the natural polythene in the pre-... 

Such signature must not be accepted as an agreement to repeat its deviation in future batches, unless the master manufacturing method has to be amended accordingly. 

On the other hand, low hysteresis mixes can be achieved by dispersion methods that increase interaggregate distances prolonged or two-stage mixing or master-batch techniques have been used in order to decrease hysteresis (Hess, 1991 Sone et al., 1992). 

In the manufacture of color master batches, the current industry practice is to perform eritieal color measurements off-line. Typically, a sample of the pelletized color concentrate is diluted with natural resin at a standard ratio and milled, extruded or injection molded into a physieal form suitable for visual and instrumental evaluation. These methods are slow and labor intensive. Furthermore, they do not lend themselves well to statistical process eontrol strategies because of the time lag between production and testing. Since relatively few samples can be examined, laboratory measurements may not give a true indication of the consistency of the concentrate product over the entire manufacturing process. 

Kurokawa et al. [258-260] developed a novel but somewhat complex procedure for the preparation of PP/clay nanocomposites and studied some factors controlling mechanical properties of PP/clay mineral nanocomposites. This method consisted of the following three steps (1) a small amount of polymerizing polar monomer, diacetone acrylamide, was intercalated between clay mineral [hydrophobic hectorite (HC) and hydrophobic MMT clay] layers, surface of which was ion exchanged with quaternary ammonium cations, and then polymerized to expand the interlayer distance (2) polar maleic acid-grafted PP (m-PP), in addition was intercalated into the interlayer space to make a composite (master batch, MB) (3) the prepared MB was finally mixed with a conventional PP by melt twin-screw extrusion at 180°C and at a mixing rate of 160 rpm to prepare nanocomposite. Authors observed that the properties of the nanocomposite strongly dependent on the stiffness of clay mineral layer. Similar improvement of mechanical properties of the PP/clay/m-PP nanocomposites was observed by other researchers [50,261]. 

A two-step method was used to prepare carbon nanotube (CNT)/(EVA)/(PE) and CNT/(PC)/PE composites. First, CNT-EVA and CNT-PC master batches were obtained by solution-phase processing, and second, the CNT master batches were melt mixed with PE. Phase morphological observations revealed decrease in the size of the dispersed particles in the composites (Li et al. 2007). 

Owing to the large aspect ratio of individual day platelets, the performance of nanocomposites is sensitive to the degree of dispersion and, thus, to the preparation method. For example, better performance has been reported for PP-based PNC prepared by the master batch (MB) method than by a single pass (SP) [378]. A similar... 

Table 5.3 lists the principal experimental methods used in dynamic mechanical testing. Of the experiments considered below, the thermal scan mode (method 1) is the technique most commonly used by thermal analysts. Here typical applications in quality control or processing look for differences in material batches, thermal history, different grades, reactivity, and other characteristics. The stepped isotherm (or step isothermal) experiment (method 2) is used mainly in studies involving detailed mechanical property determination for structural analysis, vibration damping applications, and for determining time-temperature superposition master curves. Method 3 (fast scan or single isotherm) is application specific. 

The dyed PP spunbonds are very important and they can be produced by three methods mixing of natural chips with master batch chips, mixing of natural chips with dyestuff powder, and melting of the master batch in a second extruder and metering of this melt into the main extruder, where it is mixed with the main melt stream. 

Spin dyeing can be carried out with the following methods addition of master batch granulates to the naturally white spinning quantity, admixture of the... 

---