Monomodal copolymer of ethylene for injection molding and process for its preparation

Patent metadata

Field	Value
Publication number	US-10626202-B2
Application number	US-44908208-A
Country	US
Kind code	B2
Filing date	Jan 15, 2008
Priority date	Feb 1, 2007
Publication date	Apr 21, 2020
Grant date	Apr 21, 2020

Abstract

Monomodal copolymers of ethylene and molding compositions comprising such copolymers, wherein the copolymers have a density determined according to DIN EN ISO 1183-1, variant A in the range from 0.938 to 0.944 g/cm3, a melt index MFR21 determined according to ISO 1133 at 190° C. under a load of 21.6 kg in the range from 12 to 17 g/10 min, a weight average molar mass Mw in the range from 140 000 g/mol to 330 000 g/mol, a polydispersity Mw/Mn in the range from 9 to 17, and a content of comonomer side chains per 1000 carbon atoms Cx equal to or above a value defined via equation (I) Cx=128.7−134.62×d′, wherein d′ is the numerical value of the density of the copolymer in g/cm3, the use of the copolymers for producing injection-molded articles, as well as injection-molded articles comprising the copolymers, and process for the preparation of such monomodal copolymers.

First claim

What is claimed is:

1. A process comprising:
copolymerizing ethylene with at least one C 3 -C 12 1 -olefin to produce a monomodal copolymer comprising ethylene and at least one 1-olefin, wherein the monomodal copolymer has:
(i) a M w in a range of from 150,000-300,000,
(ii) a polydispersity M w /M n in a range of from 11-16,
(iii) a density determined according to DIN EN ISO 1183-1, variant A of 0.940-0.942 g/cm 3 ,
(iv) a melt index MI 5 of 0.5-1 g/10 min,
(v) a melt index MFR 21 (ISO 1133; 190° C., 21.6 kg) of 12-17 g/10 min,
(vi) an environmental stress cracking resistance of 25-49 hours, and
(vii) 0.1 to 10 C x comonomer side chains per 1000 carbon atoms, wherein C x is equal to or above a value defined by the equation (I)
C x =128.7−134.62× d′   (I),

wherein d′ is the numerical value of the density of the copolymer in g/cm 3 ,
(viii) 0.1-1% by weight of an additive; and
(ix) a spiral length of greater than 40 cm at an MFR 21 of 14-15.6, and
preparing an injection molded article comprising the monomodal copolymer of ethylene and at least one 1-olefin.

2. The process according to claim 1 , wherein ethylene and at least one C3-C12 1-olefin are copolymerized in the presence of a chromium catalyst.

3. The process according to claim 1 , wherein the copolymerization is conducted in at least one gas-phase reactor.

4. The process according to claim 1 , wherein the copolymerization is carried out at a temperature which is in a range restricted by an upper limit defined by equation (III)
T H =173+6 d ′/(0.840− d ′)  (III)

and a lower limit defined by equation (IV)
T L =178+7.3 d ′/(0.837− d ′)  (IV)

in which the variables have the following meanings:
T H is the highest reaction temperature in ° C.;
T L is the lowest reaction temperature in ° C.; and
d′ is the numerical value of the density d of the copolymer to be synthesized.

5. The process according to claim 1 , wherein the injection molded article is selected from the group consisting of a cap, closure, screw cap, screw closure, tube shoulder, engineering part pipe fitting and fuel tank module part.

Assignees

• Foettinger Klaus
• Hecker Manfred
• Berger Lothar
• Karer Rainer
• Lilge Dieter
• Basell Polyolefine Gmbh

Inventors

• Foettinger Klaus
• Hecker Manfred
• Berger Lothar
• Karer Rainer
• Lilge Dieter

Classifications

• C08F210/16 Primary

  Copolymers of ethene with alpha-alkenes, e.g. EP rubbers · CPC title

• C08F2500/12

  Melt flow index or melt flow ratio · CPC title

• C08F2/34

  Polymerisation in gaseous state · CPC title

• C08F2500/11

  Melt tension or melt strength · CPC title

• C08F4/24

  Oxides · CPC title