Suitable additives are described, for example, in Additives 25  for Plastics Handbook, John Murphy, Elsevier, Oxford 1999  or Plastics Additives Handbook Hans Zweifel, Hanser,  Munich 2001.  The content of phenolic OH end groups was obtained by IR  measurement. For this purpose, a differential measurement of  a solution of 2 g of polymer in 50 ml of dichloromethane 60  compared with pure dichloromethane was carried out, and the  difference in extinction at 3582 cm-$^{1 }$was determined.  The coating test simulates the behaviour of the correspond› ing material in the injection-moulding process in respect of  coating formation. The coating test was carried out as fol› lows:  Relative Solution Viscosity  The relative solution viscosity was determined in dichlo› romethane at a concentration of 5 g/1 at 25°  C.  Content of Phenolic OH End Groups:  Coating Test:  The examples which follow serve to illustrate the invention  by way of example, without implying any limitation.  The invention therefore also provides mouldings or extru› dates produced from the polycarbonates according to the  invention, such as, for example, disks for writable optical data  storage means or materials from the automotive glazing sec› tor, such as, for example, light-diffusing plates.  The polycarbonates according to the invention are out› standingly suitable as substrate materials for transparent  injection-moulded parts, in particular for injection-moulded  parts that are to be coated, such as, for example, transparent  sheets, lenses, optical storage media or carriers for optical  storage media, or articles from the automotive glazing sector,  such as, for example, light-diffusing plates. It is accordingly  possible to produce from the polycarbonate according to the  invention in particular optical storage media or carriers for  optical storage media, such as, for example, writable optical  data storage media, which have good coatability and wetta› bility and are suitable, for example, for the application of dyes  from solution, in particular from non-polar media. In addi› tion, the optical injection-moulded parts produced from these  polycarbonates have a lower tendency to contamination.  The addition of these substances is preferably carried out in  conventional devices to the finished polycarbonate.  The additives and added substances, or mixtures thereof,  can be added to the polymer melt in the form of a solid, that is  to say in the form of a powder, or in the form of a melt.  Another type of metering is the use of masterbatches, that is  to say a mixture of the additive or added substance with the  polymer, preferably with polycarbonate, which has been  homogenised by compounding, or mixtures of masterbatches  of the additives or additive mixtures.  In order to achieve the desired properties, the different  additives can be combined with one another. These additives  and added substances can be added to the polymer melt indi› vidually or in any desired mixtures or in a plurality of differ› ent mixtures, either directly during isolation of the polymeror  after the melting of granules in a so-called compounding step.  carbonates. However, for the reasons described at the begin› ning, the amount of additives used must be kept as small as  possible. Examples of such additives are mould release  agents based on stearic acid and/or stearic alcohol, particu› larly preferably pentaerythritol stearate, trimethylolpropane  tristearate, pentaerythritol distearate, stearyl stearate and  glycerol monostearate, as well as conventional heat stabilis› ers.  20 g of polymer granules were dried for 4 hours at 120°  C.  and then placed in a small aluminium dish having a diameter  of 80 mm. The small dish was then placed in a metal block  which had a circular recess with a diameter of 85 mm and a  depth of 50 mm, the metal block already having been heated  electrically to 300°  C.  The recess in the metal block was covered with a 0.03 mm  thick aluminium foil, and a coolable metal block was in tum  applied from the rear side. This metal block is provided with  cooling channels through which water at an approximate  temperature of 20°  C. flows.  During the measuring time, which is 4 hours, volatile con› stituents evaporating out of the granules condense on the  aluminium foil. When carrying out the measurement it must  be ensured that the aluminium foil effectively seals the  sample chamber to the outside.  The test apparatus was subsequently cooled down to ambi› ent temperature, When ambient temperature had been  reached, the aluminium foil was removed and weighed on a  microbalance. The amount of condensate was determined  from the difference in the weight of the foil before and after  the test. The coating value is the weight of the coating pre› cipitated on the foil relative to the original weight of the  granules, in percent.  Measurement of the Electric Field Strength:  The influence of the process according to the invention was  checked by means of measurements of the electric field  strength on finished injection-moulded parts, in the present  case on disks. The following injection-moulding parameters  and conditions were established for the production of these  optical disks:  Machine: Netstal Discjet  Matrix: audio stamper  Cycle time: 4.4 s  Substrate dimensions: audio CD  Temperature of the composition: 310-33 0°  C.  Tool temperature, matrix side: 60°  C.  Before the start of the injection-moulding process, a new  audio stamper was inserted into the machine. Before the new  stamper was inserted, the entire injection-moulding installa› tion was cleaned of previous material so that the measured  values were not falsified.  The electric field strength was measured using a field meter  from Eltec (EMF 581230). Immediately after the end of the  injection-moulding process, the disk was removed by means  of a robot arm and deposited. The disk was not allowed to  come into contact with metal, because otherwise the measure› ment is impaired. Furthermore, any ionisers present had to be  switched off.  The field meter was positioned above the disk at a distance  of 100 mm from the horizontal disk surface. The distance of  the field meter from the inside edge of the disk was 29 mm and  was oriented centrally over the writable surface. The disk was  not moved. Measurement of the field accordingly took place  within a period of from 3 to 10 seconds following completion  of the injection-moulding process.  The measuring device was connected to an x/y plotter, on  which the values were printed out. A particular integral value  of the electric field was accordingly assigned to each mea› sured disk. In order to limit the amount of data, 100 measure- ments were carried out after the start of the process, that is to  say the corresponding electric field strength on the surface of  the first 100 disks was recorded. After in each case 60 min- utes, a further 100 measurements were carried out. After the  3rd series of measurements, that is to say after about 2 hours,  the measurement was stopped.  EXAMPLES  US 7,814,626 B2  22  21 