Method for preparing coated pipe
A technology for pipes and coatings, applied in the field of compositions for polymer coating pipes
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Embodiment approach
[0069] According to a preferred embodiment, the first ethylene homopolymer or copolymer has a weight of 940-980 kg / m 3 Density and melt flow rate MFR of 100-1000g / 10min 2 , the first ethylene polymer mixture has 940-980kg / m 3 Density and melt flow rate MFR of 100-1000g / 10min 2 . Still preferably said first ethylene homopolymer or copolymer is a first ethylene homopolymer and said second ethylene homopolymer or copolymer is a second ethylene homopolymer. Thus, preferably no alpha-olefins are introduced into said first and second polymerization steps.
[0070] The second polymerization step is thus preferably carried out as a slurry polymerization to prepare MFR 2 100-1000 g / 10 min, preferably 200-800 g / 10 min of the first ethylene polymer mixture. Thus, the molar ratio of hydrogen to ethylene is suitably 250-2000 mol / kmol, preferably 300-1000 mol / kmol, particularly preferably 300-800 mol / kmol. Further, polymerization is suitably carried out at a temperature above the crit...
Embodiment 1
[0152] make capacity 50dm 3 The loop reactor was operated at a temperature of 70 °C and a pressure of 58 bar. Feed ethylene, 1-butene, propane diluent and hydrogen into the reactor so that the feed rate of ethylene is 2.0kg / h, the feed rate of 1-butene is 80g / h, and the feed rate of hydrogen is 5g / h and the feed rate of propane was 55kg / h. In addition, a solid polymerization catalyst component prepared as described in the catalyst preparation section above was introduced into the reactor along with a triethylaluminum cocatalyst such that the Al / Ti molar ratio was about 15. The production rate was estimated at 1.3 kg / h.
[0153] The slurry stream is continuously withdrawn and introduced into a loop reactor with a volume of 150 dm 3 And run at a temperature of 95°C and a pressure of 55 bar. Further ethylene, propane diluent and hydrogen were charged to the reactor to give a fluid mixture with an ethylene concentration of 5.9% by mole, a hydrogen to ethylene ratio of 110 mol...
Embodiment 2
[0158] Repeat the technological process of embodiment 1, difference is that changing volume is 150dm 3 The conditions in the loop reactor were such that the ratio of hydrogen to ethylene in the reactor was 410 mol / kmol and the ethylene concentration was 5.0 mol-%. The resulting homopolymer had an MFR of 380 g / 10 min 2 . The ratio of 1-butene to ethylene was 10 mol / kmol (resulting from prepolymerized carried-over species). Change volume to 350dm 3 The conditions in the loop reactor were such that the ratio of hydrogen to ethylene in the reactor was 420 mol / kmol and the ethylene concentration was 4.8 mol-%. The resulting homopolymer mixture had an MFR of 420 g / 10 min 2 . The ratio of 1-butene to ethylene was 5 mol / kmol (due to carryover from the previous reactor). Finally, the conditions in the gas phase reactor were adjusted so that the hydrogen to ethylene ratio in the reactor was 26 mol / kmol, the 1-butene to ethylene ratio was 420 mol / kmol and the ethylene concentration...
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Abstract
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