Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F110/00—Homopolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F110/02—Ethene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/02—Ethene

Definitions

• the present invention relates to a process for the polymerization of ethylene or copolymerization of ethylene with vinylically unsaturated comonomers at temperatures from 110 to 350 ° C. and pressures from 1000 to 4000 bar in the presence of peroxidic polymerization initiators.
• the invention further relates to the use of non-polymerizable carboxylic acids in such processes.
• the present invention was therefore based on the object of avoiding the use of such peroxides which decompose at low temperature and nevertheless of achieving an effective and controllable initiation of the polymerization.
• Both homopolymers of ethylene and copolymers of ethylene with various vinylically unsaturated comonomers can be prepared by the process according to the invention.
• One embodiment of the process according to the invention therefore consists in the copolymerization of ethylene with ⁇ , ⁇ -unsaturated carboxylic acids or derivatives of such carboxylic acids.
• the ⁇ , ⁇ -unsaturated carboxylic acids which can be used as comonomers in the process according to the invention are generally short-chain carboxylic acids having 3 to 8 carbon atoms. Examples include acrylic acid, methacrylic acid, crotonic acid, maleic acid and fumaric acid, acrylic acid and methacrylic acid being preferred comonomers.
• esters of C to C 6 alkanols that is to say ethyl, propyl, butyl, pentyl and hexyl esters, can also be used as comonomers.
• Another preferred embodiment of the process relates to the copolymerization of ethylene with vinyl acetate.
• the polymerization and copolymerization process according to the invention is preferably carried out at temperatures between 140 and 320.degree. C., particularly preferably between 160 and 300.degree. C., with polymerizations being carried out with sensitive comonomers, in particular carboxylic acid esters, preferably at temperatures below 220.degree.
• the preferred pressure range for carrying out the method according to the invention is between 1500 and 3500 bar, in particular between 2000 and 3000 bar.
• the process according to the invention can be carried out in various reactors known to the person skilled in the art.
• processes in Ruhr autoclaves such as those for 3
• Tubular reactors are understood to mean tubular polymerization vessels, the ratio of the length to the diameter of the pressure-resistant tubes generally being in the range from 10,000 to 60,000 to 1.
• Information on ethylene high-pressure polymerization processes using tubular reactors can be found, for example, in "Ulimanns Encyklpadie der technical chemistry", 1980, 4th edition, volume 19, pages 167 to 178, Verlag Chemie GmbH, D-6940 Wemheim.
• reactor types can be used, e.g. Reactors with or without cold gas addition, reactors with pressurized water cooling, etc.
• the polymerization is initiated by peroxidic polymerization initiators.
• peroxides are considered which only decompose m radicals at relatively high temperatures. Decay temperature is understood to mean the temperature at which 50% of the peroxide molecules disintegrate within one minute.
• Suitable peroxidic polymerization initiators are, for example, 1,1-bis (t-butyl peroxy) cyclohexane, 1,1-bis (t-butyl peroxy) butane, t. -Butylperoxy- 3, 5, 5 - t ⁇ methylhexanoat, t.-Butylperoxybenzoat, 2, 5 -Bis (t. -Butylperoxy) -2,5 -dimethylhexane, t. - Butyl cumyl peroxide, diet. -butyl peroxide and 2, 5 -bis (t .butylperoxy) 2, 5 -d ⁇ methyl-3 -hexin m consideration, particularly preferred is tert. -butyl peroxide used.
• those with a decomposition temperature of at least 150 ° C. are used as peroxidic polymerization initiators. Both individual peroxides and mixtures of different peroxides can be used.
• aliphatic and aromatic carboxylic acids come into consideration as non-polymerizable carboxylic acids with which the rate of decomposition of the peroxidic initiators can be influenced.
• Short-chain aliphatic carboxylic acids in particular C 1 -C 4 -alkane carboxylic acid, have proven particularly useful for regulating the peroxide decomposition in the course of the polymerization.
• the use of acetic acid is particularly advantageous.
• the amount or concentration of the non-polymerizable carboxylic acids used depends on the type and decomposition temperature of the peroxides used and on the desired initiator activity. It must therefore be tailored to the specific polymerization requirements. In general, amounts of 0.05 to 1.0% by weight, in particular 0.08 to 0.8% by weight, based in each case on the total amount of ethylene in the polymerization mixture, have proven useful.
• the polymerization mixture can additionally contain customary additives, such as molecular weight regulators.
• molecular weight regulators such as hydrogen, ketones, aldehydes, alcohols, ethers and linear and branched hydrocarbons. Propane, propylene, methyl ethyl ketone or propionaldehyde are preferably used.
• the polymerization regulators are generally used in amounts of 0.2 to 5 mol percent, based on the ethylene to be polymerized.
• ethylene was polymerized at a throughput of 1.4 t / h under a pressure of 2800 bar and an inlet temperature of 180 ° C.
• TBPIN tert-butyl per - 5 oxy-3, 5, 5 - trimethylhexanoate, decomposition temperature 160 ° C
• DTBP di-tert-butyl peroxide , Decay temperature 190 ° C
• Ethylene 5 was polymerized under conditions similar to those in Example VI, but without TBPIN and in the presence of 0.1% by weight of acetic acid. See Table 1 for results
• Ethylene was polymerized under the conditions of Example 1, but in the presence of 0.5% by weight of acetic acid. See Table 1 for results

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• Chemical & Material Sciences (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Polymerisation Methods In General (AREA)
• Polymerization Catalysts (AREA)

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• 1998
  • 1998-04-24 DE DE19818216A patent/DE19818216A1/de not_active Withdrawn
• 1999
  • 1999-04-12 BR BR9909845-8A patent/BR9909845A/pt not_active Application Discontinuation
  • 1999-04-12 JP JP2000545896A patent/JP2002513048A/ja active Pending
  • 1999-04-12 EP EP99917973A patent/EP1090044A1/de not_active Withdrawn
  • 1999-04-12 CN CN99805437A patent/CN1298414A/zh active Pending
  • 1999-04-12 HU HU0101834A patent/HUP0101834A3/hu unknown
  • 1999-04-12 KR KR1020007011751A patent/KR20010034822A/ko not_active Application Discontinuation
  • 1999-04-12 WO PCT/EP1999/002450 patent/WO1999055738A1/de not_active Application Discontinuation

Non-Patent Citations (1)

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