DE2559749A1 - PROCESS FOR MANUFACTURING SHAPED BODIES FROM POLYLACTAMES BY ACTIVATED ANIONIC POLYMERIZATION OF MEDIUM LACTAMES - Google Patents

Description

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B 549-19 / Sa

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March 31, 1977

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Harwe AG, Schönenwerd / Switzerland

Process for the production of molded articles from polylactams by activated anionic polymerization of medium lacquer

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The invention relates to a method for producing molded articles from polylactams through activated anionic polymerization of medium lactams. Under the expression used here "Medium lactams" are lactams with 12 to 15 carbon atoms understood in the lactam ring, i.e. the lactams of n-tridecanoic, myristic and η-pentadecanoic acid and particularly preferably the Lauric acid.

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Telephone: Telegraph: Office hours: Bank accounts: Postal check account:

Lindau (08382) 6917 054374 by appointment Bayer. Vereinsbank Lindau (B) No. 120 8578 (BLZ 73520074) 'Munich 295 25-8C

Hypo-Bank Lindau (B) No. 6670-278 920 (BLZ 735 206 42) Volksbank Lindau (B) No. 51720 000 (BLZ 735 90120)

In the polymerization of lactams, it is known that the monomer becomes Lactam melted and the melt with at least one Catalyst and at least one activator mixed, whereupon the polymerization reaction takes place, for which from CH-PS 479 and DT-OS 2 108 759 it is also already known to carry out the polymerization in such a way that a portion of the lactam melt is incorporated mixes the catalyst and the activator into the other part.

US Pat. No. 3,793,255 also discloses a process for producing moldings by activated anionic polymerization known from laurolactam, in which two lactam melts are separated with a catalyst and an activator under respective nitrogen exposure and processed over separate and under the same temperature exposure as the melts standing pipes are fed to a mixing device and then flow into a form, the processed Partial melts on their way to the mixing device to flow through each of a siphon-like coiled pipe system are brought. It is made from the usual polycaprolaktam completely different properties of the polymer obtained.

The flaw of this process, however, lies in the fact that, although initially polymerized cast products of very excellent Properties can be obtained, but these properties drop very sharply after a short period of time and finally, in numerous cases, products with inadequate properties are obtained »

A modification of this process is proposed in DT-OS 25 07 549 for the production of molded articles from polylactams. Here, for example, a Pol3 ^r laurinlactam is obtained from laurinlactam with the following properties that differ completely from the known polycaprolactams:

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_{a yield stress 0 Q} measured according to DIN 53 455 of approx. 470 to approx. 520 kp / cm,

an elongation measured according to DIN 53 455 at yield stress £, - of approx. 17 to approx. 25 % _f

a tensile strength 6b measured according to ISO R 527 of approx 500 to about 630 kgf / cm,

_{an elongation at break £ R} measured according to ISO R 527 of approx. 200 to 350 %,

a modulus of elasticity E measured in accordance with DIN 53 457 Section 2.3 from about 19,000 to about 22,000 kgf / cm,

_{a limit bending stress O n} measured in accordance with ISO R 178 of approx. 750 to approx. 1000 kp / cm,

_{a notched impact strength a v} measured according to DIN 53 453 of about 55 to 65 kpcra / cm,

^{a ball indentation hardness 10 »f} measured according to DIN 53 456 level C of approx. 1000 to approx. 1050 kp / cm,

an abrasion resistance of about 158 to about 129 mnr / rpm,

a time elongation stress Ö-1/10000 measured according to DIN 53 444

Λ 1

(23 ° c / 95 90 from about 50 to about 60 kp / cm and

a creep modulus E / IOOO (O 20.0) measured according to DIN 53 444 from about 13,000 to about 14,000 kgf / cm.

However, this method is not yet free from deterioration either in the course of a longer pot life, "pot life" being understood here as the time during which the catalyst-containing Partial melt and the activator-containing partial melt are kept separate before mixing and pouring.

The reason for this unsatisfactory behavior on the one hand and the rather rapid failure to achieve optimal properties of products over time is not simply a

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watch. However, it has been under extensive research found in the scope of the present invention that on the one hand the catalyst-containing lactam melt is more viscous, than the activator-containing lactam melt, so that this already results in an uneven flow of the separate melts and causing an uneven feed to the mixing zone. Try to make the viscosity of the two more uniform Partial melting by increasing or decreasing temperature of the individual melts also failed, as this resulted in the most favorable one required for uniform spraying Temperature changed and deteriorated products were obtained. In these tests it was also found that with regard to the two partial melts and the temperature at the injection nozzle very special temperature conditions have to be observed in order to achieve useful results at all. However, even if the above two points were strictly observed, it was found that this was still not the case was sufficient to obtain a satisfactory product, but that it is additionally required that a part

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the gases arising or occurring in the mixing zone and the partial polymerisation which takes place there are discharged from this mixing zone and must be returned to the boiler in order to obtain an excellent product.

An object of the invention is therefore a process for the production of molded articles from polylactams, in which from properties that differ from the known polycaprolactams over a longer period of time can be obtained and the disadvantages described above do not occur.

A further object consists in a device suitable for carrying out such a method.

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The accompanying drawing shows a particularly preferred configuration of such an embodiment of the device shown, partly in section.

The invention relates to a process for the production of molded articles from polylactams by the activated anionic polymerization of lactams, in particular laurolactam, in which two lactam melts are prepared separately with a catalyst and an activator with the respective exposure to nitrogen and via separate pipes that are subject to the same temperature exposure as the melts are fed to a mixing device and then flow into a form, which is characterized in that (a) to a partial lactam melt held in a separate kettle with stirring a known polymerization catalyst at below 17O ¹ G and above 160 ° C with a tolerable deviation of + 1 ⁰ O is added and stirred, (b) offset in time to an equivalent partial lactam melt kept in a separate kettle with stirring a known activator at one, a few ⁰ C lower than that of the first Melt present, but is added and stirring is also within the range of temperature below 170 ⁰ C to above 160 ⁰ C and a tolerable deviation of + 1 ⁰ C temperature, melting the above, according to (a) and (b) obtained while maintaining their temperatures each withdrawn by a gear pump from their tanks and from the two gear pumps via straight pipelines with a slight incline of a maximum of 10 ° relative to the horizontal, the pipelines being at least 1/3 larger in volume than they correspond to the delivery rate of the pump Guided mixing zone and there ^{briefly mixed at a temperature between 170 and 175 0} C and sprayed or potted through the spray head without pressure or with low pressure, with at least part of the resulting or entrained gases via the pipelines and gear pumps during the spraying or pouring conveyed back into the mixing tank rden. 709837/0045

The invention is explained in more detail below with reference to the drawing. As an example of the description, the manufacture chosen from molded articles made from polylaurolactam, though According to the invention, the other middle lactams can also be used, with only slightly modified ones Temperature ranges that a person skilled in the art can easily determine in simple experiments are necessary. In the drawing only the fundamentally essential parts are described, while it goes without saying that control elements, shift levers, thermometers and pressure gauges, supply lines and derivatives are also available.

In the schematic representation of the drawing, two basically identical boilers 1 and 1a are shown, which are equipped in the usual way with agitator blades 2 driven by agitators 3 and 3a and with baffle disks 4. The jacket of the boiler is equipped with heating devices that can be regulated within narrow temperature ranges, whereby electrical heating elements, superheated steam or hot oil and the like can be used as heating media in the completely customary quiet manner. The heating device is indicated schematically with 5. At the lower end, the boilers are equipped with lockable outlets 6 and 6a, while at the upper end there is a three-way valve 7 with a filler neck 8 reaching into the boiler and a two-way valve 9. Furthermore, on the upper part of each boiler there is a bomb 10 or 10a with release levers 11, 11a, which are used to release the catalyst into the boiler 1 and the activator into the boiler 1a. Further, in the boiler wall, a thermostat 12 is inserted, which has a response accuracy of at most 1.5 ⁰ G.

Vertically below the outlets 6 and 6a of the boiler are two gear pumps 13 and 13a with counter-rotating gears and a lower drain 15 and 15a, respectively. The gears are of considerable size and run fairly slowly in order to avoid any severe turbulence in the melt passing through them.

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By adjusting the pump, the quantities of melt flowing out of the melting kettle 1 and 1a can be precisely regulated.

A practically straight conveyor pipe 16 leads from the pump outlet 15, 15a to the inlet head of the mixing zone 9, which can be shut off by means of a shut-off 17 The order of magnitude is up to a maximum of 10 °, preferably 5 °. The dimensioning of the volume of this tube 16 is also very important for the invention. It must namely be dimensioned to a volume which is practically twice as large as the delivery rate of the gear pumps 13 and 13a. This means that during operation this conveying pipe may be filled up to about halfway by the outflowing melt and under no circumstances may more than 2/3 of this pipe be filled with the melt. Of course, this delivery pipe is also thermally insulated. The funnel-shaped mixing zone 19, in which the catalyst-containing or activator-containing melts coming from the melting kettles 1 and 1a via the conveying pipe 16 or the conveying pipe (not shown) from the pump 13a flow, serves to smoothly mix the two melts, carefully avoiding any strong flow or turbulence is to be avoided. The mixing zone runs out into a lockable pouring nozzle 20. The entire Gießkop.f 22 is also kept at a certain temperature by means of heating devices (not shown), with a thermostat likewise ensuring a very precise temperature ^{constancy with an accuracy of response of around 1 ° C.} If necessary, a weak agitator 23 with a small agitator blade 24 can be attached in the mixing zone in the center above the pouring head. As a rule, however, this agitator and the actuation of the impeller are not required and the impeller may only

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be operated extremely slowly, as too much agitation causes a disturbing flow or turbulence. Basically the agitator only serves to remove any jams that may occur and to ensure a smoother outflow bring.

During operation, the agitator 3 is operated in the boilers 1 and. 1a equivalent amounts of the lactam melt are introduced through the filler neck 8 and at the same time nitrogen is also introduced through this neck by means of the three-way valve 7 to flush the kettle. Care must be taken to exclude air, oxygen and atmospheric humidity during the entire process, without the measures required for this having to be specified, since they are familiar to any person skilled in the art. After the appropriate temperature setting has been reached in each boiler, the required amount of catalyst, which is generally in the range from about 0.1 to 0.6 mol%, preferably 0.3 to 0, is first fed to the boiler 1 from the bomb 10 by means of the lever 11 , 4 MoI-SKi, based on lactam, lies, released and stirred. The temperature of the catalyst-containing melt is then held at and below a value of 170 ⁰ C and above a value of 160 ⁰ G, preferably in the range from 169.5 to 167.5 ⁰ C for fifteen minutes to half an hour, preferably about 20 Minutes, stirred. The introduction of nitrogen is also recommended during this period.

Calculated from the addition of the catalyst to melting kettle 1 becomes with a delay of 5 to 15 minutes, preferably about 10 minutes, to the partial lactam melt in the melting kettle 1a from the bomb 10a by means of the release lever 11 then the activator in an amount of about 0.05 to 0.5 mol-? 6, preferably 0.08 to 0.15 mol%, based on lactam, added and the activator-containing melt in the boiler 1a at a somewhat

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lower lying than the temperature of the melt in the boiler 1 in the temperature range below 17O ⁰ C and 16O above ³ G, preferably maintained at a temperature range of 166-164 ^C C.

This delayed addition ensures that the viscosities of the partial melts in both tanks are approximately the same. The catalysts and activators used are quite common. As examples of catalysts for the production of the polylactams, metallic sodium, sodium amide, alkali lactams, anhydrous ethanol and carbon dioxide may be mentioned, of which sodium amide is particularly preferred. Examples of activators in the production of the polylactams are isocyanates, for example phenyl isocyanate, substituted lactams, for example N-aryl lactams and III-cyanol lactams, substituted ureas and reaction products of carbamic acid chloride with heterocyclic compounds such as imidazole. The use of phenyl isocyanate as activator is particularly preferred. After the two Teilschroelzen have been stirred for the required time of about 1/2 hour for the catalyst-containing melt and a stirring time shortened by 5 to 15 minutes for the activator-containing melt, casting can begin in casting molds that do not need to be heated beforehand and atich none Heat dissipation and the like. Need to be started. For this purpose, after opening the corresponding closures, the melt from the boiler 1 enters the gear pump 13, which is matched with the additional gear pump 13a in terms of the delivery rate and then flows through the inclined delivery pipe 16, which is filled up to 2/3 by the flowing melt at the most v / ground, into the mixing zone 19. In a mirror-inverted manner, the activator-containing nozzle flows from the melting vessel 1a also into this common mixing zone 19. When the two partial melts are mixed, the polymerization reaction begins and it occurs partly through decomposition of the catalyst and activator, partly a considerable amount of gas due to the reaction and partly due to entrained gases. This amount of gas forms above the mixing zone and in the free part of the conveyor pipe

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an extremely beneficial air cushion for carrying out the process. It is now very important for the success of the present Process according to the invention that .these resulting gases do not remain as a whole in the casting compound and discharged into the molds through the pouring nozzle 20, but that at least some of these gases pass through the for this purpose larger-sized delivery pipes 16 and the opposing gear part of the gear pumps back into the Mixing vessel 1 and 1a are returned. From these mixing tanks they pass through like the introduced nitrogen gas the filler neck and the two-way valve 9.

It has also been found to be very advantageous that the stirrers in the kettles in Remain calm, otherwise in an inexplicable way in the polymerizing materials in the foimaa segregation can occur. In no case should the gear pumps and the agitators be allowed to operate at this speed be operated that foam formation occurs. Rather, it must be used in every way for uniform, steady mixing to be taken care of.

It has also proven to be very important that the pouring head 22 and the pouring nozzle are kept at a slightly higher temperature than the temperature of the incoming partial melts, namely within a range of approximately above 170 ³ C to 175 ⁰ C, preferably 171 to 173 ⁰ C.

As a very advantageous if not shown in the drawing, the attachment proved of heat shields in addition to the pouring head, which are heated to about 190 to 220 ⁰ C, which heat the emerging jet on the one hand and on the other hand, shield the environment of moisture. Potting takes place practically without pressure, even if pressures down to the low pressure range can be used.

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It is interesting that in the present implementation there is no significant heat development either during the reaction or during the solidification, as is otherwise the case with porylactams and polyamides, so that no preheating or removal of heat from the molds is necessary, local overheating itself are excluded in the large casting and products can be obtained with hitherto not Polylaktamen properties obtained, for example, show no melting point, but disintegrate crumbly after solidification when heated to temperatures of about 220 to 28O ⁰ C. In particular, they have a high degree of crystallinity and, as a result, result in very enormous strength values, as can be seen from Table I below.

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Table I.

characteristic Measurement method dimension 470 - - ..52O dimension 46 - 51 C Mechanical properties 17-25 Stretching tension & § DIN 53 455 kp / cm ² 500-630 N./inm ² 49-62 Elongation at stretching tension. Se DIN 53 455 200-350 Tear strength C ^ ISO R 527 kp / cm ² 19,000-22,000 N / mm ² 1864-2158 elongation ζ χ ISO R 527 q /
/ 0 750-1000 74-98 Young's modulus E DIN 53 457 from 2.3. kp / cm ~ " 55-65 N / mm ² 55-65 irenz bending stress og ISO R 178 kp / cm ^ 1000-1050 N / mm ² 98-103 impact strength a ^. DIN 53 453 ρ
kpcm / cmi 158-129 kJ / m ² Ball indentation hardness 10 " DIN 53 456 level C kp / cm 50-60 N / mm ² 4.9-5.9 A. abrasion resistance Taber-Abrazer mnr / rpm I3OOO - 14000 1275-1373 Time expansion stress <w1000
(23 ° C / 95%) ⁷ DIN 53 444 kp / cm N / mm ² Creep modulus E / 1000, (q 20.0
1 '' DIN 53 444 kp / cm Ν / ranr

(O CO CaJ

O O

cn

cn cn CD

to

- VS-

It is essential that these physical properties be obtained not only at the beginning of the potting but also at the End of potting and after several interruptions of the casting operation are obtained. That is a major benefit compared to the procedure according to US Pat. No. 3,793,255 Gußraasse is dragged along, the crystallinity is lower and after a longer period of casting, the strength values drop significantly and sometimes to the point of uselessness. According to the invention In contrast, there is no bubble formation, a void-free and homogeneous product from start to finish. end of Potting with excellent properties.

The following examples further illustrate the invention.

example 1

The two kettles 1 and 1a were first flushed with nitrogen and then 20 kg of pure laurolactam were introduced into each kettle and melted therein while stirring. After the melting vessel had 1 reaches a constant temperature of 168.5 ⁰ C, was removed from the bomb 10 is an amount of 0.32 mol% of sodium, based on lactam, is added as a catalyst while maintaining the temperature and at this temperature, the contents were the kettle stirred for 25 to 30 minutes. Care was taken that the temperature did not drop more than 1 ° below the above temperature.

With a delay of 10 minutes, calculated since the addition of the catalyst to boiler 1, an amount of 0.12% phenyl isocyanate, based on lactam, was added as an activator to the melt in boiler 1a, which was kept constant ^{at 165 ° C., from bomb 10a} stirred at a constant temperature of 165 ° C. for 15 to 20 minutes.

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Then the closures to the two gear pumps and the entrances to the mixing zone of the pouring head were opened and the stirring in the kettles was interrupted, so that practically equally viscous currents were pumped through the slightly inclined delivery pipes 16 into the mixing zone, which were at 172 ⁰ C + 1 ⁰ C was maintained, but the delivery pipes were only half full and the gases formed during the mixing and the initiation of the reaction and any gases entrained re-entered the melting tank through this space via the gear pumps. Any overpressure that might arise was discharged via the two-way valve connected to the filler neck. The combined melts, which contained very little gas, emerged from the pouring nozzle by gravity and were poured into molds at normal temperature. The total casting time was about 50 minutes. Samples were taken from the molded pieces obtained at the beginning, molded pieces obtained after 30 minutes and with the molded pieces obtained after 50 minutes, whereby no fundamental differences could be found between the physical properties of these molded pieces, apart from scatter errors within 2% . All test pieces showed no blistering, were free of voids and. exceptionally homogeneous.

For comparison, the above experiment was repeated, but the apparatus specified in US Pat. No. 3,793,255 with the siphon-like feed to the pouring nozzle was used. Furthermore, the temperature in both tanks was kept the same, ie at an average value of 167 ^° C., the catalyst and activator were added simultaneously in the amounts indicated above and the gases could not be recirculated from the mixing head due to the siphon-like design.

While the first samples obtained in this comparison are definitely had comparable properties as above, after only 20 minutes there was considerable blistering and shrinkage

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formation and inhomogeneity of the samples obtained, while the final samples due to the low crystallinity had such low strength values that they were practically unusable. It was also found that in the boilers a considerable amount of the more viscous catalyst-containing melt remained.

Example 2

The above experiment according to the invention of Example 1 was repeated exactly identical, but attached to the casting head in addition flat heat shields which were heated during casting to 200 ⁰ C, but had no contact with the casting compound.

Practically identical products as in Example 1 were obtained, but they had an even better appearance.

Example 5

The experiment according to the invention according to Example 1 was exactly identical repeated, but this was an amount of 0.38 mol-5X> Anhydrous ethanol was added as a catalyst, while the addition of phenyl isocyanate as an activator in the other melting kettles was delayed by 14 minutes compared to the addition of catalyst.

Here, too, moldings with the same excellent properties as in Example 1 were obtained.

Due to the excellent properties, the new Polylactam moldings can be used in numerous fields, in particular also instead of metal moldings. You own even metallic sound.

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Claims (10)

Claims /1. Process for the production of molded articles from polylactams ^ by the activated anionic polymerization of lactams, in particular laurolactam, in which two lactam melts are prepared separately with a catalyst and an activator under the respective application of nitrogen and fed to a mixing device via separate pipelines that are subjected to the same temperature as the melts and then flow into a mold, characterized in that (a) to a held in a separate part of the boiler-lactam melt with stirring a per se known polymerization catalyst at a below 170 ⁰ C and above 160 ⁰ C and a tolerable deviation of + 1 ⁰ C is added and stirred, (b) time-contrast offset to one held in a separate vessel equivalent part-lactam melt with stirring a per se known activator at a few ⁰ C lower than that of the first underlying melt, but also within the range from below 170 ^° C. to above 160 ^° C. with a tolerable deviation of + 1 ^° C. temperature is added and stirred, the melts obtained above according to (a) and (b) each by a gear pump while maintaining their temperatures withdrawn from their tanks and from the two gear pumps via straight pipelines with a slight incline of a maximum of 10 ° from the horizontal, the pipelines being at least 1/3 larger in volume than they correspond to the delivery rate of the pump, led to the mixing zone and added there A temperature between 170 and 175 ⁰ C is briefly mixed and injected or poured through the spray head without pressure or with low pressure, with at least some of the resulting or entrained gases being conveyed back into the mixing tank via the pipelines and gear pumps during the spraying or pouring . 7 0 9837/0045 - vf- SL 2. The method according to claim 1, characterized in that for the production of polylaurinlactam the processing temperature of the catalyst-containing melt is 169.5 to 167.5 ⁰ C and that of the activator-containing melt is 166 to 164 ⁰ C, 3. The method according to claim 1 or 2, characterized in that that with a pot life of about one hour, the time delay for adding the activator is about 5 to 15 minutes, 4. The method according to claim 1 to 3, characterized in that the stirring time before the start of spraying or pouring 20 to 30 Minutes after the addition of activator or catalyst. 5. The method according to claim 1 to 4, characterized in that the management of the melt over about 5 ° th sloping pipelines. the management of the melt about 5 ° in relation to the horizontal 6. The method according to claim 1 to 5, characterized in that the casting or spraying is carried out while the molds are shielded by means of heat shields heated ^{to about 190 to 220 0 C, in particular about 200 ° C.} 7. The method according to claim 1 to 6, characterized in that the catalyst-containing melt at a temperature of 168.5 ⁰ C and the activator-containing melt at a temperature of 165 ⁰ C with a discharge pipe inclination of 5 ° and a temperature of the spray head of 172 ⁰ C, each with a temperature tolerance of + 1 ⁰ C, are processed. 8. Polylaurin lactam obtained by one of the processes according to Claims 1 to 7. 9. Polylaurin lactam, obtained by one of the processes according to Claims 1 to 7 with the following physical characteristics: 709837 / 0CU5 - yg - a yield stress fiu measured according to DIN 53 455 of about 470 to about 520 kgf / cm, an elongation measured in accordance with DIN 53 455 at yield stress £ ₅ of approx. 17 to approx. 25%, _{a tensile strength O 1} measured in accordance with ISO R 527, from about 500 to about 630 kp / cm, _{an elongation at break £ R} measured according to ISO R 527 of approx. 200 to 350 %, a modulus of elasticity measured in accordance with DIN 53 457 Section 2.3 E from about 19,000 to about 22,000 kgf / cm, _{a limit bending stress O n} measured in accordance with ISO R 178 of approx. 750 to approx. 1000 kp / cm, _{a notched impact strength a v} measured according to DIN 53 453 of ρ -K about 55 to 65 kpcm / cm, a ball indentation hardness measured according to DIN 53 456 level C 10 " from about 1000 to about 1050 kgf / cm, an abrasion resistance of about 158 to about 129 mm / rpm, measured by means of a Taber Abrazer, a time elongation stress cL / 1000 (23 ° c / 95 %) measured according to DIN 53 444 of about 50 to about 60 kp / cm and a creep modulus E "/ 1000 (£> 20.0) of about 13,000 measured according to DIN 53 444 up to about 14,000 kgf / cm. 10. Apparatus for performing the method according to claim to 7, characterized by two separate heatable boilers equipped with agitators (3, 3a) and agitator blades (2) (1, 1a), the filler neck (8, 8a) closed on the upper part with a three-way valve (7, 7a) and two-way valve (9, 9a) and a bomb-like insertion device (10 or 10a) for catalyst or activator is equipped and a lower one Process (6, 6a) has two separate gear pumps (13, 13a) that are matched to one another, following these processes (6, 6a) 709837/0045 - w- and from these pumps to the funnel-shaped mixing zone (19) with pouring mouthpiece (20) leading opposite the horizontal up to 10 ° inclined conveyor pipes (16), which are dimensioned in terms of volume so that their passage is about twice as large is how the delivery rate of the assigned gear pumps (13 » 13a) and heating devices (21) for the pouring head (22) comprising the mixing zone (19). 709837/0045 '