CA1139488A - Process for production of chemically blended composition of non-elastomeric ethylene resins - Google Patents
Process for production of chemically blended composition of non-elastomeric ethylene resinsInfo
- Publication number
- CA1139488A CA1139488A CA000356263A CA356263A CA1139488A CA 1139488 A CA1139488 A CA 1139488A CA 000356263 A CA000356263 A CA 000356263A CA 356263 A CA356263 A CA 356263A CA 1139488 A CA1139488 A CA 1139488A
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- copolymer
- ethylene
- polymer
- alpha
- weight
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Abstract
Abstract of the Disclosure This invention relates to an improved process for production of a chemically blended composition of non-elastomeric ethylene resins. Thus the invention provides: in a process for the production of a chemically blended com-position of non-elastomeric ethylene resins in a multiplicity of steps in the presence of a catalyst composed of a transition metal catalyst component and an organometallic compound, which comprises (a) a step of forming (i) an ethyl-ene polymer or an ethylene/alpha-olefin copolymer having an alpha-olefin con-tent of up to 15% by weight, said polymer or copolymer (i) having an intrinsic viscosity (n) of 0.3 to 3, and (b) a step of forming (ii) an ethylene/alpha-olefin copolymer having an alpha-olefin content of 0.2 to 30% by weight which is more than that of the polymer or copolymer (i), said copolymer (ii) having an intrinsic viscosity (n) of 1 to 12 which is at least 1.5 times that of the polymer or copolymer (i), said step (a) being performed first and then step (b) being performed in the presence of the product of step (a), or step (b) being performed first and then step (a) being performed in the presence of the product of step (b); the improvement wherein in steps (a) and (b), ethylene is polymerized or copolymerized with the alpha-olefin.
(1) in the presence of a catalyst composed of (A) a highly active titanium catalyst component containing titanium, magnesium and halogen and being capable of yielding an ethylene polymer in an amount of at least 250 g/milli-mole of a titanium atom.hr.kg/cm2 of ethylene pressure and (B) an organoaluminum compound, (2) so that the weight ratio of the polymer or copolymer (i) formed ill step (a) to the copolymer (ii) formed in step (b) is (30-less than 60) :
(above 40 - 70), and (3) so that the resulting chemically blended composition has an intri-sic viscosity (n) of 1 to 6 and an alpha-olefin content of 0.2 to 20% by weight.
(1) in the presence of a catalyst composed of (A) a highly active titanium catalyst component containing titanium, magnesium and halogen and being capable of yielding an ethylene polymer in an amount of at least 250 g/milli-mole of a titanium atom.hr.kg/cm2 of ethylene pressure and (B) an organoaluminum compound, (2) so that the weight ratio of the polymer or copolymer (i) formed ill step (a) to the copolymer (ii) formed in step (b) is (30-less than 60) :
(above 40 - 70), and (3) so that the resulting chemically blended composition has an intri-sic viscosity (n) of 1 to 6 and an alpha-olefin content of 0.2 to 20% by weight.
Description
~ his invention relates to an i~?roved process for production of a chemically blended ccmposition of non-elastomeric ethyl ene resins having superior proces-sability, impact strength and resistance to environmental 5 stres~ cracking and being free from a trouble of fish eyesO
Suitable ethylene resins for use in producing various molded products such as tubes, bottles and other receptacles b~y extrusion molding or blow moldi.ng are 10 those whi ch have good processability in melt-molding and give molded articl es having high impact strength and high resistance to environmental stress cracki ngO
Known proposals for providing a non-elastomeric ethylene resin composition having these desirable pro-15 perties are discLosed, for example~ in Japanese PatentPublication NoO 22007/70 (corresponding to British Pa~tent No~ 1,03] ,869~ or Japanese ~aid-Open Patent Publication No 19637/73 (corresponding to West German DOS 2,233~983 and British Patent NoO 1~391.,804) which involve use of 20 a composition containing (a) a homopolymer of ethylene or a copolymer of ethylene and a small amount of an alpha~
olefin having a medium degree of molecular weig~t an.d (b) a high-molecular-weigh-t copolymer o~ ethylene and a minor proportion of an alpha-olefi.n~ the amOunt of the alpha 25 oleîin being larger than that in the copolymer (a)O
.:
~ he first-mentioned prior Patent ~blication discloses a physically blended composition consisting of 15 to 50% by weight of a linear ethylene resin havi-ng a melt index of 2 to 20 as an ethylene polymer or co-polymer corresponding to (a) and 85 to 5~/0 by weight ofa high-molecular-weight ethylene/butene-l copolymer having a melt index of OoO001 to 005 as a resin component correspondin.g to (b)~ Preparation of such a physically blended composition has the disadvantage that a ph~sical blending means is required, and unless the blending is performed in the liquid state in solution in a suitable solvent, the blending becomes insufficient, and a number of fish eyes occur in the resulting molded articles~
~he latter-mentioned prior patent discloses a method for preparing a chemically blended composition including an embodiment of forming an ethylene polymer or an ethylene~alpha-olefin copolymer corresponding to (a) above and forming an ethylene~alpha-olefin copolymer corresponding to (b) above in the presence of the result-ing product (a)O As the resulting chemically blendedcomposition, a composition consisting o~ at least 6~/o by wel~lt of the polymer or copolymer (a) and 5 to ~/0 by weight of the copolymer (b) is recommended. The Patent also states that; unlike the physically blended com-position~ favorable results are obtained with a chemicallyblended composition containing no-t more than 4~% by weight of the copolymer (b). The largest con-tent of the copolymer (b) formed in all of the Examples in this Patent is 26% by weightO The Patent discloses only ordinary Ziegler catalysts, and fails to describc the use of a highly active titanium catalyst component containing titanium, magnesium and halogenO In this Patent, the polymerization is carried out under such conditions that the resulting polymer dissolves in a polymerization solvent.
It has been lound however that when a chemically blended composition having the polymer or copol~Jmer (a) and the copolymer (b) in the propor-tions recommended in the above patent is formed by slurry polymerization~
molded articles produced from -the resulting composition cannot be free from the trouble of fish eyes=
l'he present inventors have made investigc-Ltions in order to provide a method for producing a che~ically blended comLposition of ethylene resins which has imLproved processability, impact stre~-~gth and resistance to en-vironmental stress cracking while avoiding the trouble of fish eyes which has heretofore been difficult to avoid simultaneously with the achievement of these improved propertiesO
It has consequently been found that L chemically blended composition of ethylene resins having supcrior processability~ high impact strength and superior resis-tance to environmental s-tress cracXing and being ~ree from fish eyes can be easily produced by a process for the production Or a chemically blended composition of non-elastomeric ethylene resins in a multiplicity of steps in the presence of a catalyst composed of a tran-sition metal catalyst component and an organometallic compound, which comprises (a) a step of forming (i) an ethylene polymer or an ethylene/a]pha-olefin copolymer having an alpha olefin con-tent of up -to 15% by weight9 said polymer or copolymer (i) having an intrinsic v-i.scosity ~) of 003 to 3~ and (b) a step of forming (ii) an ethylene/alph&-ol.efin copolymer ha~.ng an alpha-olefin content of 002 to 30/0 by weight which is more than that of the polymer or copolymer (i), said copolymer (ii) having an in-trinsic viscosity (^l~) of 1 to 1~ which is at least 105 times that of the polymer or copolymer (i), step (a) being perf(rmed first and then s-tep (b) being perf-)rmed 35 in the presence of the product of step (a), or step (b) being performed first and then step (a) being per-formed in th.e presence of the product of step (b), ~139~88 characterized in that ethylene is polymerized or co-polymerized with the alpha-olefin under conditions (l) to (3) belo~ in steps (a) and (b)o (l) ~he polymerization or copolymerization is carried out in the presence of a catalyst composed of (A) a highly active titanium catalyst component containing titanium9 magnesium and halogen and being capable of yielding an ethylene polymer in an amount of at least 250 ~millimole of a titanium atomohrokg/cm2 of ethylene pres~ure and (~) an organoaluminum compoundO
Suitable ethylene resins for use in producing various molded products such as tubes, bottles and other receptacles b~y extrusion molding or blow moldi.ng are 10 those whi ch have good processability in melt-molding and give molded articl es having high impact strength and high resistance to environmental stress cracki ngO
Known proposals for providing a non-elastomeric ethylene resin composition having these desirable pro-15 perties are discLosed, for example~ in Japanese PatentPublication NoO 22007/70 (corresponding to British Pa~tent No~ 1,03] ,869~ or Japanese ~aid-Open Patent Publication No 19637/73 (corresponding to West German DOS 2,233~983 and British Patent NoO 1~391.,804) which involve use of 20 a composition containing (a) a homopolymer of ethylene or a copolymer of ethylene and a small amount of an alpha~
olefin having a medium degree of molecular weig~t an.d (b) a high-molecular-weigh-t copolymer o~ ethylene and a minor proportion of an alpha-olefi.n~ the amOunt of the alpha 25 oleîin being larger than that in the copolymer (a)O
.:
~ he first-mentioned prior Patent ~blication discloses a physically blended composition consisting of 15 to 50% by weight of a linear ethylene resin havi-ng a melt index of 2 to 20 as an ethylene polymer or co-polymer corresponding to (a) and 85 to 5~/0 by weight ofa high-molecular-weight ethylene/butene-l copolymer having a melt index of OoO001 to 005 as a resin component correspondin.g to (b)~ Preparation of such a physically blended composition has the disadvantage that a ph~sical blending means is required, and unless the blending is performed in the liquid state in solution in a suitable solvent, the blending becomes insufficient, and a number of fish eyes occur in the resulting molded articles~
~he latter-mentioned prior patent discloses a method for preparing a chemically blended composition including an embodiment of forming an ethylene polymer or an ethylene~alpha-olefin copolymer corresponding to (a) above and forming an ethylene~alpha-olefin copolymer corresponding to (b) above in the presence of the result-ing product (a)O As the resulting chemically blendedcomposition, a composition consisting o~ at least 6~/o by wel~lt of the polymer or copolymer (a) and 5 to ~/0 by weight of the copolymer (b) is recommended. The Patent also states that; unlike the physically blended com-position~ favorable results are obtained with a chemicallyblended composition containing no-t more than 4~% by weight of the copolymer (b). The largest con-tent of the copolymer (b) formed in all of the Examples in this Patent is 26% by weightO The Patent discloses only ordinary Ziegler catalysts, and fails to describc the use of a highly active titanium catalyst component containing titanium, magnesium and halogenO In this Patent, the polymerization is carried out under such conditions that the resulting polymer dissolves in a polymerization solvent.
It has been lound however that when a chemically blended composition having the polymer or copol~Jmer (a) and the copolymer (b) in the propor-tions recommended in the above patent is formed by slurry polymerization~
molded articles produced from -the resulting composition cannot be free from the trouble of fish eyes=
l'he present inventors have made investigc-Ltions in order to provide a method for producing a che~ically blended comLposition of ethylene resins which has imLproved processability, impact stre~-~gth and resistance to en-vironmental stress cracking while avoiding the trouble of fish eyes which has heretofore been difficult to avoid simultaneously with the achievement of these improved propertiesO
It has consequently been found that L chemically blended composition of ethylene resins having supcrior processability~ high impact strength and superior resis-tance to environmental s-tress cracXing and being ~ree from fish eyes can be easily produced by a process for the production Or a chemically blended composition of non-elastomeric ethylene resins in a multiplicity of steps in the presence of a catalyst composed of a tran-sition metal catalyst component and an organometallic compound, which comprises (a) a step of forming (i) an ethylene polymer or an ethylene/a]pha-olefin copolymer having an alpha olefin con-tent of up -to 15% by weight9 said polymer or copolymer (i) having an intrinsic v-i.scosity ~) of 003 to 3~ and (b) a step of forming (ii) an ethylene/alph&-ol.efin copolymer ha~.ng an alpha-olefin content of 002 to 30/0 by weight which is more than that of the polymer or copolymer (i), said copolymer (ii) having an in-trinsic viscosity (^l~) of 1 to 1~ which is at least 105 times that of the polymer or copolymer (i), step (a) being perf(rmed first and then s-tep (b) being perf-)rmed 35 in the presence of the product of step (a), or step (b) being performed first and then step (a) being per-formed in th.e presence of the product of step (b), ~139~88 characterized in that ethylene is polymerized or co-polymerized with the alpha-olefin under conditions (l) to (3) belo~ in steps (a) and (b)o (l) ~he polymerization or copolymerization is carried out in the presence of a catalyst composed of (A) a highly active titanium catalyst component containing titanium9 magnesium and halogen and being capable of yielding an ethylene polymer in an amount of at least 250 ~millimole of a titanium atomohrokg/cm2 of ethylene pres~ure and (~) an organoaluminum compoundO
(2) ~he polymerization or copolymerization is carried out so that the weight ratio of the polymer or copolymer (i) formed in step (a) to the copolymer (ii) formed in step (b) is (30 - less than 60): (abo~e ~ - 70)O
(3) The polymerization or copolymerization is carried out so that the resulting chemically blended composition has an intrinsic viscosity ~ of l to 6 and an alpha-olefin content of 002 to 2~/o by weightO
It has been found that the above improvement can be achieved even when the polymerization or copoly-merization is carried out under slurry polymerization conditionsc It is an object of this invention therefore to provide an improved process for production of a chemically blended composition of non-elastomeric ethylene resinsO
The above and other objects and advantages of this invention will become more apparent from the follow-ing descriptionO
In the present invention, the intrinsic viscosity (~ denotes an intrinsic viscosity determined in decalin at 135C~
In the process of this invention, the polymeri-zation or copolymerization in the ~ulti-step process comprising steps (a) and (b) is carried out in the presence of a catalyst composed of (A) a highly active titanium catalyst component containing titanium, magnesium and halogen and being capable of yielding an ethylene 1. ~;,3~
polymer i~ ar! amount of a-t least 250 g/millimol~ ~f titanium atom~hr~kg/cm2 of ethylene pressure~ and (B~
an organ~aluminum compound ~condition (1))~
~`he amOllnt of the ethylene polymer yielded is preferab3y at least 400) more preferably at lea.ct 700, g/mil'limole of titanium atom hrok ~cm2 of ethylene pres-sureO 'here is no particular upper limit to the amoun-t of the eth.ylene polymer yielded9 but for example~ -the upper lir,lit may be about 5000 g/millimole of tîtaniwn atomuhrk ~cm2 of ethylene pressure D In the preser,t invention, the amoun~t of the ethylene polymer yi~lded is that under the conditions for practicing the steps (a) and (b)o A titanium catalys-t component activa-ted with a magnesium compound is preferred as the highly ac-tive titanium catalyst componentO Examples of the highly active titanium catalys-t component (A) are a so]id titanium catalyst component containing magnesium~ titanium arid halogen as essential ingredients9 and a titaniw-n catalyst component in solution form composed of a magnesium com-pound, a solubilizing agent and a titanium compound d.is-solved in a 'hydrocarbon solventO Titanium in -the highly active cat-alyfi-t co~ponent is usually tetravalent or tri-valentO 'I'he solid titanium ca-talyst component (A) has a titanium content of preferably about 0O2 to about 18%
by weight, more preferably about 0O3 to abou-t 15~jh by weight, and a halogen/titanium mole ratiO of abou-t 4 to about 300, more preferably about 5 to about 200 D Further-more, it has a specific surface area of preferably at least about 10 m2/g~ more preferably about 20 to about 1000 m /g~ especially preferably a'bou-t 40 to abou-t 900 m2/g.
Such a solid hig'nly active titanium catalyst component (A) is widely knownj and is basically obtained by a method which comprises reac-ting a magnesium com~ound with a titanium compound to obtain a product having a high speci~ic surface area~ or a method which comprises reacting a m~agnesium compound having a high specific surface area with a titanium compoundn According to a typical exrLmple, it is prepared by copulverization of a magnesium compound and a -ti-tanium compound, reaction a~
eleva-ted. temperatures of a magnesium compound having a sufficiently high specific surface area with a titanium compound, or reaction at elevated temperatures of an oxygen-containing magnesium compound with a titaniur.
compound, or by a method which corLLprises reacting a magnesiuml compound treated with an electron donor, ~rith a titanium co~Lpound with or without prior treatment with an organoaluminum co~Lpound or a halogen-containing silicon compoundt.
Various magnesium compounds are available for the production of the highly active solid titanium cata-lyst component (A)~ Exampl~s include magnesium chloride, magnesium bromide., magnesium iodide, magnesium fluoride9 magnesiul-n hydroxide9 magnesium oxide, magnesium h~droxy-halides, alkoxymagnesiums, alkoxy Magnesium halides, aI~loxy magn~siums9 aryloxymagnesium halides, alkyl magnesium halides, and mixtures of these~ These col,Lpounds may be produced by any method of productionO The magnesium compounds nay contain other metals or electron donors~
Tetravalent titanium co~L~ounds of the formula Ti(OR)4 ~LXm (wherein R represent~s a hydrocarborl radical containing 1 to 12 carbon a-toms, X is haloc~en9 .~ml 0~ m~ 4) can be cited as examples oL the titarliUm com~ollnd used for production of the highl.y active solid titanium catn-lyst compo~!ent (A)o ~xamples include titanium te-tra-halid~s such as7 Tic]4~ TiBr4 or TiI4; alkoxytitaniumtrihalidcs such as Ti(OCH3)C13, Ti(OC2H5)Clz, Ti(O n-C4H9)C13~ Ti(OC2H5)Br~, and Ti(O iso-C4H9)Br3; alko~y-titanium dihalides su~h as Ti(OCH3)2C12, Ti(OC2H5)2C12, Ti(O n-C~Hg)2Cl2, and Ti(OC2H5)2Br2; trialkoxytitanium monohalides such as Ti(OCH3)3C19 Ti(OC2H5)~C19 Ti(O n-C4H9)zCl and Ti(OC2H5)~Br; and tetraalkoxytitanium such as Ti~OCH3)4, Ti(OC ~ 5S49 and Ti(O n-C~H9)4~ There can 5 ~t~
al.so be Gited titanium trihalicl.ec:;, such ax titanium. tri.-chloride, obtained by reducing titanium -tetrahalides with reducing agents such as aluminur.l~ titanium, hydrogen ox organoalurlinum compounds~ Thcse titanium c~mpounds can be utilized in combinatiorl wi-th each otherO
~ he electron donors used in the forr:la~tiorl of the highly c~c-t;ve titanium catalys~t component are9 for exa~ple, oxygen-containing compounds such as carboxylic .~cids, esters, c~thcrs, aci.d amides, aldehydes, alcoholsa ketones and water~ and nitrogen-containing compounds such as nitriles. More specifically, they include alipha-tic or aromati.c carboxylic acids, aliphatic or aromatic carboxylic acid cst~rsc" aliphatic or alicyclic ethers, aliphatic or aromatic kctones, aliphatic aldehydes, aliphatic alcohois, aliphatic acid amines~ water, alipha-tic or aromatic nitrilesg and aliphatic or aroma~tic aminesO
It is recoL~ended that usually the electron donor be chosen ~rom alipha-tic carboxylic acids having 1 to 12 carbon atOrls9 aromatic carboxylic acids having 7 or 8 carbon atoms, esters between aliphatic saturatcd carboxylic acids having 1 -to 12 carbon atoms or aliphatic unsaturated carboxylic acids having 3 to 12 carbon atoms and aliphatic saturated alcohols having 1 to 12 carbon ato~s or aliphatic unsaturated alcohols having 2 to 1.2 carbon atoms, esters between aronati( carboxylic acids having 7 to 12 carbon atoms and aliphatic alcohols having 1 -to 12 carbon atoms, aliphatic ethers having 2 -to 12 c,rbon atomC" cyclic ethers h?ving 3 or 4 carbon atoms, aliphc-ltic k~-t~-nes, hav-ing ? to 13 carbon atoms9 aliphatic aldehydes h~ving 1 -to 12 carbon. a-toms, aliphatic alcohols having 1 -to -L2 carbon atoms, aliphatic acid a~ides having 1 to 12 carbon a-toms, aliphatic nitriles having 2 to 12 carb~n atoms9 aromatic ni-triles h.lving 7 -to 12 carbon atoms, aliphatic ar~.nes having ] t~, 12 carbon atoms~ and Iromatic amines having 5 to 7 ca.rb(:)n a~tomsO
Specific examples o~ these elec-tron donors are aliphatic carboxylic acids such as aceti^ acid~ propionic ~ ~, Q ~
c?Cid9 V?~ `riC acid and aeryJie acicl; ~rcmcrltLc c-~:.bo~.~lie aeids sucll s benzoie aeid sr pht~Lalie ~eid9 a:lipJlc-ltic earboxyl;c ?eid estt?rc. sueh C'ts rc,~-thyl. formate9 l~ eyl.
formate, ~-thyl aeetatt9 buty] aeetate9 vin-yl acet?~-te9 methyl aer~late, oetyl aeetate, etlLyl laura-te ^nd oe-tyl laurate; aromatie earboxylie aCi d es-ters sueh as r^~ethyl benzoe-.~te., ~thyl benzoate9 oetyl p hydroxybenzoc?te~ e~nd dioetyl phthalc~Ate; aliphatie ~c.thtrs .sueh cas ethy] ether9 hexyl ether9 allylbutyl ether and methylundeeyl ether~
eyelie ethers sueh ?S tetrahydrc)fllran9 dioxanc ancl. tri-oxane; aliPhatie ke-tones sueh as aee-tone9 methyl i~s.~butyl ketone, e-tllyl butyl ketone and dihexyl ke-torle9 ar~llatiC
ketones such as .?ee-tophenone; aliphc?tie aldehydes ueh c?s propionaldehyde; alipha-tic alcohGls such as netharlol9 ethanol9 ic.opropanol9 hexa~nol., 2--c-thylhexanol9 oetanol and doean~ lipha-tie nitril.(:s sueh as aee-tonit;rile, valeronitri:~e I.nd Ic:ry].oni-t:rile~ arorl~?tie nitril e5 sueh as benzcni-trile arld phth~ )rlitrilej ~nd alipha~tic aeid c-,Lr.~.i.deS such as ~eetar.~ideO l'h.^ aleohol.s are nocst preferred~
The orgc~Anoc~lurlinurl e(~r.p()uncl used in preparing the high:Ly Ietive titarliUr.l eatalyst eorLponen-t (A) ILay be ehosen fr-~ those exer~Lpli.-fied he-reirlbelow about -the organoalw~inur. e~?talyst eonponen-t (B) in this inv~ntionO
'rhe hal.ogFl-l-contairling silicon cor.~.pound used in preparing the highl.~ aetive titaniur~ ea-talyst eomponent is a COr.pOUnd having ha.logt~n diree-tly bonded to a silieon atJ~I9 and ineludesg for exar~p1.e~, si]ie(~r:l tetraha]ides, silieo:r alkylhalid.es9 c:ilicon llkoxy:hali.(Les, arlcl halop~jlyciloxant;~
Speeifie exar~ples are SiC149 CH~SiCL39 (CHz)2Si(,1 (CH ) SiCl~ (CHzO)SiCl3s (C?~5o~2~icl2~ ( 2 5 -3 (C6H50)SiC13 ~ ypica] me-thods for preparing the highly aetive ti-taniu~l e~-t.~lyst eo~ponent (A) are cLiselosed9 f~r exc^~ple, in Japanese P.-tent I:ublication NoO 3409?/71, Japanese 3~5 ~atent E~lblication NoO 34094/71. (correspondin~ -to U. SO
P~~tent No 3~759,884 -:,ncl :E3riti~;n Pc~tent No~ 19189,038)9 J~?panese P?tent Publication NoO 34098/71 (corrcsp ~rcLing 3~
to United States Patent No. 3,644,318 and ~est German DOS 1,795,197), Japanesc Patent Publication No. 41676/72 (corresponding to British Patent No. 1,286,867);
Japanese Patent Publication No. 46269/72 (corresponding to British Patent No.
1,292,853), Japanese Patent Publication No. 32270/75 (corresponding to United States Patent No. 4,071,674, and British Patent No. 1,433,537), and Japanese Patent Publication No. 1796/78 (corresponding to United States Patent No.
It has been found that the above improvement can be achieved even when the polymerization or copoly-merization is carried out under slurry polymerization conditionsc It is an object of this invention therefore to provide an improved process for production of a chemically blended composition of non-elastomeric ethylene resinsO
The above and other objects and advantages of this invention will become more apparent from the follow-ing descriptionO
In the present invention, the intrinsic viscosity (~ denotes an intrinsic viscosity determined in decalin at 135C~
In the process of this invention, the polymeri-zation or copolymerization in the ~ulti-step process comprising steps (a) and (b) is carried out in the presence of a catalyst composed of (A) a highly active titanium catalyst component containing titanium, magnesium and halogen and being capable of yielding an ethylene 1. ~;,3~
polymer i~ ar! amount of a-t least 250 g/millimol~ ~f titanium atom~hr~kg/cm2 of ethylene pressure~ and (B~
an organ~aluminum compound ~condition (1))~
~`he amOllnt of the ethylene polymer yielded is preferab3y at least 400) more preferably at lea.ct 700, g/mil'limole of titanium atom hrok ~cm2 of ethylene pres-sureO 'here is no particular upper limit to the amoun-t of the eth.ylene polymer yielded9 but for example~ -the upper lir,lit may be about 5000 g/millimole of tîtaniwn atomuhrk ~cm2 of ethylene pressure D In the preser,t invention, the amoun~t of the ethylene polymer yi~lded is that under the conditions for practicing the steps (a) and (b)o A titanium catalys-t component activa-ted with a magnesium compound is preferred as the highly ac-tive titanium catalyst componentO Examples of the highly active titanium catalys-t component (A) are a so]id titanium catalyst component containing magnesium~ titanium arid halogen as essential ingredients9 and a titaniw-n catalyst component in solution form composed of a magnesium com-pound, a solubilizing agent and a titanium compound d.is-solved in a 'hydrocarbon solventO Titanium in -the highly active cat-alyfi-t co~ponent is usually tetravalent or tri-valentO 'I'he solid titanium ca-talyst component (A) has a titanium content of preferably about 0O2 to about 18%
by weight, more preferably about 0O3 to abou-t 15~jh by weight, and a halogen/titanium mole ratiO of abou-t 4 to about 300, more preferably about 5 to about 200 D Further-more, it has a specific surface area of preferably at least about 10 m2/g~ more preferably about 20 to about 1000 m /g~ especially preferably a'bou-t 40 to abou-t 900 m2/g.
Such a solid hig'nly active titanium catalyst component (A) is widely knownj and is basically obtained by a method which comprises reac-ting a magnesium com~ound with a titanium compound to obtain a product having a high speci~ic surface area~ or a method which comprises reacting a m~agnesium compound having a high specific surface area with a titanium compoundn According to a typical exrLmple, it is prepared by copulverization of a magnesium compound and a -ti-tanium compound, reaction a~
eleva-ted. temperatures of a magnesium compound having a sufficiently high specific surface area with a titanium compound, or reaction at elevated temperatures of an oxygen-containing magnesium compound with a titaniur.
compound, or by a method which corLLprises reacting a magnesiuml compound treated with an electron donor, ~rith a titanium co~Lpound with or without prior treatment with an organoaluminum co~Lpound or a halogen-containing silicon compoundt.
Various magnesium compounds are available for the production of the highly active solid titanium cata-lyst component (A)~ Exampl~s include magnesium chloride, magnesium bromide., magnesium iodide, magnesium fluoride9 magnesiul-n hydroxide9 magnesium oxide, magnesium h~droxy-halides, alkoxymagnesiums, alkoxy Magnesium halides, aI~loxy magn~siums9 aryloxymagnesium halides, alkyl magnesium halides, and mixtures of these~ These col,Lpounds may be produced by any method of productionO The magnesium compounds nay contain other metals or electron donors~
Tetravalent titanium co~L~ounds of the formula Ti(OR)4 ~LXm (wherein R represent~s a hydrocarborl radical containing 1 to 12 carbon a-toms, X is haloc~en9 .~ml 0~ m~ 4) can be cited as examples oL the titarliUm com~ollnd used for production of the highl.y active solid titanium catn-lyst compo~!ent (A)o ~xamples include titanium te-tra-halid~s such as7 Tic]4~ TiBr4 or TiI4; alkoxytitaniumtrihalidcs such as Ti(OCH3)C13, Ti(OC2H5)Clz, Ti(O n-C4H9)C13~ Ti(OC2H5)Br~, and Ti(O iso-C4H9)Br3; alko~y-titanium dihalides su~h as Ti(OCH3)2C12, Ti(OC2H5)2C12, Ti(O n-C~Hg)2Cl2, and Ti(OC2H5)2Br2; trialkoxytitanium monohalides such as Ti(OCH3)3C19 Ti(OC2H5)~C19 Ti(O n-C4H9)zCl and Ti(OC2H5)~Br; and tetraalkoxytitanium such as Ti~OCH3)4, Ti(OC ~ 5S49 and Ti(O n-C~H9)4~ There can 5 ~t~
al.so be Gited titanium trihalicl.ec:;, such ax titanium. tri.-chloride, obtained by reducing titanium -tetrahalides with reducing agents such as aluminur.l~ titanium, hydrogen ox organoalurlinum compounds~ Thcse titanium c~mpounds can be utilized in combinatiorl wi-th each otherO
~ he electron donors used in the forr:la~tiorl of the highly c~c-t;ve titanium catalys~t component are9 for exa~ple, oxygen-containing compounds such as carboxylic .~cids, esters, c~thcrs, aci.d amides, aldehydes, alcoholsa ketones and water~ and nitrogen-containing compounds such as nitriles. More specifically, they include alipha-tic or aromati.c carboxylic acids, aliphatic or aromatic carboxylic acid cst~rsc" aliphatic or alicyclic ethers, aliphatic or aromatic kctones, aliphatic aldehydes, aliphatic alcohois, aliphatic acid amines~ water, alipha-tic or aromatic nitrilesg and aliphatic or aroma~tic aminesO
It is recoL~ended that usually the electron donor be chosen ~rom alipha-tic carboxylic acids having 1 to 12 carbon atOrls9 aromatic carboxylic acids having 7 or 8 carbon atoms, esters between aliphatic saturatcd carboxylic acids having 1 -to 12 carbon atoms or aliphatic unsaturated carboxylic acids having 3 to 12 carbon atoms and aliphatic saturated alcohols having 1 to 12 carbon ato~s or aliphatic unsaturated alcohols having 2 to 1.2 carbon atoms, esters between aronati( carboxylic acids having 7 to 12 carbon atoms and aliphatic alcohols having 1 -to 12 carbon atoms, aliphatic ethers having 2 -to 12 c,rbon atomC" cyclic ethers h?ving 3 or 4 carbon atoms, aliphc-ltic k~-t~-nes, hav-ing ? to 13 carbon atoms9 aliphatic aldehydes h~ving 1 -to 12 carbon. a-toms, aliphatic alcohols having 1 -to -L2 carbon atoms, aliphatic acid a~ides having 1 to 12 carbon a-toms, aliphatic nitriles having 2 to 12 carb~n atoms9 aromatic ni-triles h.lving 7 -to 12 carbon atoms, aliphatic ar~.nes having ] t~, 12 carbon atoms~ and Iromatic amines having 5 to 7 ca.rb(:)n a~tomsO
Specific examples o~ these elec-tron donors are aliphatic carboxylic acids such as aceti^ acid~ propionic ~ ~, Q ~
c?Cid9 V?~ `riC acid and aeryJie acicl; ~rcmcrltLc c-~:.bo~.~lie aeids sucll s benzoie aeid sr pht~Lalie ~eid9 a:lipJlc-ltic earboxyl;c ?eid estt?rc. sueh C'ts rc,~-thyl. formate9 l~ eyl.
formate, ~-thyl aeetatt9 buty] aeetate9 vin-yl acet?~-te9 methyl aer~late, oetyl aeetate, etlLyl laura-te ^nd oe-tyl laurate; aromatie earboxylie aCi d es-ters sueh as r^~ethyl benzoe-.~te., ~thyl benzoate9 oetyl p hydroxybenzoc?te~ e~nd dioetyl phthalc~Ate; aliphatie ~c.thtrs .sueh cas ethy] ether9 hexyl ether9 allylbutyl ether and methylundeeyl ether~
eyelie ethers sueh ?S tetrahydrc)fllran9 dioxanc ancl. tri-oxane; aliPhatie ke-tones sueh as aee-tone9 methyl i~s.~butyl ketone, e-tllyl butyl ketone and dihexyl ke-torle9 ar~llatiC
ketones such as .?ee-tophenone; aliphc?tie aldehydes ueh c?s propionaldehyde; alipha-tic alcohGls such as netharlol9 ethanol9 ic.opropanol9 hexa~nol., 2--c-thylhexanol9 oetanol and doean~ lipha-tie nitril.(:s sueh as aee-tonit;rile, valeronitri:~e I.nd Ic:ry].oni-t:rile~ arorl~?tie nitril e5 sueh as benzcni-trile arld phth~ )rlitrilej ~nd alipha~tic aeid c-,Lr.~.i.deS such as ~eetar.~ideO l'h.^ aleohol.s are nocst preferred~
The orgc~Anoc~lurlinurl e(~r.p()uncl used in preparing the high:Ly Ietive titarliUr.l eatalyst eorLponen-t (A) ILay be ehosen fr-~ those exer~Lpli.-fied he-reirlbelow about -the organoalw~inur. e~?talyst eonponen-t (B) in this inv~ntionO
'rhe hal.ogFl-l-contairling silicon cor.~.pound used in preparing the highl.~ aetive titaniur~ ea-talyst eomponent is a COr.pOUnd having ha.logt~n diree-tly bonded to a silieon atJ~I9 and ineludesg for exar~p1.e~, si]ie(~r:l tetraha]ides, silieo:r alkylhalid.es9 c:ilicon llkoxy:hali.(Les, arlcl halop~jlyciloxant;~
Speeifie exar~ples are SiC149 CH~SiCL39 (CHz)2Si(,1 (CH ) SiCl~ (CHzO)SiCl3s (C?~5o~2~icl2~ ( 2 5 -3 (C6H50)SiC13 ~ ypica] me-thods for preparing the highly aetive ti-taniu~l e~-t.~lyst eo~ponent (A) are cLiselosed9 f~r exc^~ple, in Japanese P.-tent I:ublication NoO 3409?/71, Japanese 3~5 ~atent E~lblication NoO 34094/71. (correspondin~ -to U. SO
P~~tent No 3~759,884 -:,ncl :E3riti~;n Pc~tent No~ 19189,038)9 J~?panese P?tent Publication NoO 34098/71 (corrcsp ~rcLing 3~
to United States Patent No. 3,644,318 and ~est German DOS 1,795,197), Japanesc Patent Publication No. 41676/72 (corresponding to British Patent No. 1,286,867);
Japanese Patent Publication No. 46269/72 (corresponding to British Patent No.
1,292,853), Japanese Patent Publication No. 32270/75 (corresponding to United States Patent No. 4,071,674, and British Patent No. 1,433,537), and Japanese Patent Publication No. 1796/78 (corresponding to United States Patent No.
4,071,672, and British Patent No. 1,452,314).
Compounds having one Al-C bond in the molecule can be used as the organoaluminum compound (B) constituting the catalyst used in this invention.
Examples are (I) organoaluminum compounds of the general formula Rl Al(OR2) H X
(wherein R and R represent a hydrocarbon group such as an alkyl or alkenyl group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms, and may be identical or different, X represents halogen, m is a number represented by O<m<3, n is a number represented by O<n<3, p is a number represented by O_p<3, and q is a number represented by O<q<3 with the proviso that m + n ~ p + q = 3);
and (II) complex alkylated products of aluminum and a metal of Group I of the periodic table which is represented by the general formula MlAlR14 (wherein M
represents Li, Na or K, and Rl is the same as defined above).
Examples of the organoaluminum compounds (I) are comE~ollnds of the gen-eral formula Rl Al(OR )3 in which Rl and R2 are as defined above, and m ispreferably a number represented by 1.5<m<3; compounds Or the general formula R AlX3 m wherein Rl is as defined above, X represents a halogen atom, and m is preferably a number represented by O<m<3; compounds represented by the general formula R A1113 wherein R is as defined above, and m is preferably a number represented by 2<m<3; and compounds of the general formula RlmAl(OR ) Xq wherein R and R2 are as defined above, X represents a halogen atom, O<m<3, O<n<3, O<q<3, and m + n + q = 3.
3~
Specific examples of the organoaluminum compounds (I) are trialkyl aluminums such as triethyl aluminum and tributyl aluminum; trialkenyl aluminum such as triisoprenyl aluminum; partially alkoxylated alkyl aluminum, for example, dialkyl aluminum alkoxides such as diethyl aluminum ethoxide and dibutyl aluminum butoxide; alkyl aluminum sesquialkoxides such as ethyl aluminum sesquiethoxide and butyl aluminum sesquibutoxide; dialkyl aluminum halides such as diethyl alum-inum chloride, dibutyl aluminum chloride and diethyl aluminum bromide; alkyl aluminum sesquihalides such as ethyl aluminum sesquichloride, butyl aluminum sesquichloride and ethyl aluminum sesquibromide; partially halogenated alkyl aluminums, for example, alkyl aluminum dihalides such as ethyl aluminum dichlor-ide and propyl. aluminum dichloride; dialkyl aluminum hydrides such as diethyl aluminum hydride and dibutyl aluminum hydride; partially hydrogenated alkyl aluminums, for exampl.e, alkyl aluminum dihydrides such as ethyl aluminum dihy-dride and propyl aluminum dihydride; and partially alkoxylated and halogenated alkyl a].uminums such as ethyl aluminum ethoxychloride, butyl aluminum butoxy-chloride and ethyl aluminum ethoxybromide. As compounds similar to (I), organo-aluminum compounds having at least two aluminum atoms bonded through an oxygen or nitrogen atom may also be used. Examples of such compounds are 2 5)2 (C2H5)2, (C4H9)2AlOAl(c4H9)2 and (C21l5)2AlNA~(c 1-1 ) Examples of the compounds (II) are LiAl(C2H5)4 and LiAl(C7H15)~l.
Among the above-exemplified organoaluminum compounds, trialkyl alum-inums, and alkyl aluminum halides are preferred.
In the process of this i.nvention, an ethylene polymer or an ethylene/
alpha-olefin copolymer havi.ng an alpha-olefin content of up to 15% by weight, preferably up to 10~ by weight, which has an intrinsic viscosity [n]
3~
of 0.3 to 3, preferably 0.4 to 2.5, is formed in step (a). If the alpha-olefin contellt of the coyolymer (i) formed in step (a) exceeds the above-specified upper limit, the resulting chemically blended composition has poor resistance to envi-ronmental stress cracking. If the intrinsic viscosity of the polymer OI' copoly-mer (i) is lower than the above-specified lower limit, the composition has poor processability and molded articles prepared therefrom have marked surface rough-ening. On the other hand, if the intrinsic viscosity of the resulting composi~
tion is lower than the lower limit specified above, the impact strength or tear strength of the resul~ing composition is reduced.
In step (b) of the process of this invention, an ethylene/alpha--olefin copolymer (ii) is formed. The alpha-olefin content of the copolymer (ii) is larger than that of the polymer or copolymer (i), and is 0.2 to 30% by weight, preferably 0.3 to 20% by weight. The intrinsic viscosity of the copolymer (ii) is at least 1.5 times, preferably at least 2 times, that of the polymer or co-polymer (i), and is 1 to 12, preferably 1.5 -to 10.
When the alpha-olefin content and melt index of the copolymer (ii) ob-tained in step (b) are within the above-specified ranges~ the resulting chemical-ly blended composition has markedly improved impact strength and resistance to environmental stress cracking.
The steps (a) and (b) are performed in an optional order. Specifical-ly, step (a) is first performed and then step (b) is performed in the presence of the product of step (a); or step (b) is first performed, and then step (a) is performed in the presence of the product of step (b). In any case, the two steps (a) and (b) should be carried out sequentially. In other words, the polymeriza-tion in the second step must be performed in the presence of the polymerization product of the first step. A chemically blended composition having ., 3~
reduced occurrence of fish eyes is easier to obtain by using in the second step -the catalyst used in the first step, without addiilg a fresh supply of the titan-ium catalyst component in the second step.
In the process of this invention, the polymerization or copolymeriza-tion should also be carried out so that the ratio of the amount of the polymer or copolymer (i) formed in step ~a) to that of the copolymer (ii) formed in step (b) is (30 - less than 60): (above 40 - 70), preferably (40 - 55): (45 - 60) [con-dition (2)]. Furthermore, the polymerization or copolymerization should be car-ried out so that the resulting chemically blended composition has an intrinsic viscosity [n] of 1 to 6 and an alpha~olefin content of 0.2 to 20% by weight [con-dit iOII ( 3)].
By performing the polymerization or copolymerization under a set of conditions (1) to (3) described above, a chemically blended composition of non-elastomeric ethylene resins having the aforesaid improved properties can be formed with a good reproducibility of quality, and this can be achieved even by the slurry polymerization mode.
If the amount of the copolymer (ii) is less than 40% by weight which is outside the range specified in condition (2) above, fish eyes tend to form.
In the practice of the process of this invention, a multi-step process comprising steps (a) and (b) spec:ified above is employed, and the polymerization or copolymerization is carried out under a specified set of conditions (1), (2) and (3). The polymerization or copolymerization itself can be performed by known means.
Thc polymerization or copolymerization may be carried out in the liquid phase or gaseous phase in the presence or absence of an inert solvent. The liq-uid-phase polymerization can be performed in slurry or solution. The process of this invention exhibits marked effec-ts when applied to slurry polymerization or gaseous-. '.
1~3~
phase polymerizatio]l. Examples of inert solvents that can be used in the poly-merizatiorl are aliphatic hydrocarbons such as butane, pentane, hexane, heptane, octane, decane, dodecane and kerosene; alicyclic hydrocarbons such as cyclopent-ane, methylcyclopentane, cyclohexane and methylcyclohexane; and aromatic hydro-carbons such as benzene, toluene, xylene or ethylbenzene.
In performing the liquid-phase polymerization, it is desirable to use about 0.0005 to about l millimole, preferably about 0.001 to about 0.5 millimole, calculated as titanium atom, of the highly active titanium catalyst component (A), and the organoaluminum catalyst component (B) in an aluminum/titanium atomic ratio of from about 1 to about 200, preferably from about 10 to about 500, both per liter of the liquid phase. In performing the gaseous-phase polymerization, it is desirable to use about 0.0005 to a.bout 1 millimole, preferably about 0.001 to about 0.5 millimole, calculated as titanium atom, of the highly active titan-ium catalyst component (A), and the organoaluminum compound in an aluminum/titan-ium atomic ratio of from about 1 to about 2000, preferably from about 10 to 1000, both per liter of the polymerization zone.
In the performance of the process of this invention, the catalyst com-ponents may be additionally fed in the second step, but the titanium catalyst component should preferably not be additionally supplied in the second step.
The suitable polymerization temperature :is about 20 to about 300 C, preferably about 50 to about 200C, and the suitable polymerization pressure is atmospheric pressure to about 100 kg/cm .G, preferably about 2 to about 50 kg/cm .G. The gaseous-phase polymerization can be performed in the same way as in the liquid-phase polymerization except that the polyrnerization temperature is below the temperature at which the polymer melts, especially at about 20 to about 100C. To control , ., ~ ~3~
the intrinsic viscosity [~] of the polymer, hydrogen is preferably utilized.
Examples of the alpha-olefin to be copolymerized with ethylene include propylene, l-butene, l-pentene, l-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, l-octene, l-decene, l-tetradecene, and l-octadecene. Of these, alpha-olefins having 3 to 10 carbon atoms are preferred.
After the polymerization is over, the resulting chemically blended com-position can be separated in the same way as in the production of polyethylene by an ordinary Ziegler method. In many cases, the product can be used in variousapplication without performing any operation of removing the catalyst. The chem-ically blended ethylene resin composition obtained by the process of this inven-tion is suitable for extrusion molding or blow molding. It has good processabil-ity, and molded products prepared therefrom have high impact strength and high resistance to environmental stress cracking. Moreover, since the molded productshave a substantially reduced number of fish eyes, they are suitable for use as bottles, pipes, films and cable coatings.
The following Examples and Comparative Examples illustrate the process of this invention more specifically.
Example 1 Synthesis of a catalyst Commercial]y available anhydrous magTIesillTll chloride (5 moles) was sus-pended in 10 liters of dehydrated and purified hexane in a stream of nitrogen.
With stirring, 25 moles of ethanol was added dropwise over 1 hour, and the reac-tion was performed for 1 hour at room temperature. Then, 12 moles of diethyl aluminum chloride was added dropwise at room temperature, and the mixture was stirred for 2 hours. Then, 5 moles of titanium tetrachloride was added. The mixture was heated to 60C, and with stirring, reacted for 3 hours. The result-ing solid was separated by decantation, repeatedly washed with purified hexane, and then suspended in hexane. The ~s~
concentration of Ti in the hexane suspension was determined by titration. A
part of the reslllting solid was dried under reduced pressure, and examined for composition. It was found that one gram of the solid contained 72 mg of titan-ium, 205 mg of magnesium and 610 mg of chlorine.
Polymerization A 200 liter first-stage polymerization vessel was charged continuously with 50 liters/hr of dehydrated and purified hexane, 80 millimoles/hr of tri-ethyl aluminum, and 2 millimoles/hr, calculated as Ti atom, of the supported catalyst obtained above. While discharging the contents of the polymerization vessel at a predetermined rate, ethylene and hydrogen were introduced at 80C
into the vessel at a rate of 15.5 kg/hr, and 26 Nm3/hr, respectively. Ethylene was thus polymerized continuously in the first stage with an average residence time of 2 hours at a total pressure of 7 kg/cm .
The hexane suspension containing polyethylene formed by the polymeriza-tion (ethylene polymer content 300 g/liter; intrinsic viscosity [~] of polyethyl-ene 1.10; melt index of the polymer 24.0 g/10 min) was conducted -to a flush drum at the sanne temperature as the polymerization temperature. ~Iydrogen contained in the suspension was separated, and the residue was wholly introduced into a 200 liter second-stage polymerization vessel. Without supplying additional catalyst, purified hexane was fed at a rate of 50 liteIs/hr, arld wh-ile discharging the con-tents of the vessel at a predetermined rate, ethylene, l-butene, and hydrogen were introduced at a rate of 15.5 kg/hr, 600 g/hr, and 1.2 Nm3/hr, respectively.
~hus, ethylene was copolymerized continuously with l-butene in the second stage with a residence time of l hour at a total pressure of 7 kg/cm2.
The effluent from the second-stage polymerization vessel contained 300 g/liter/hr of an ethylene polymer composition. The polymer had an intrinsic viscosity [~] of 2.65 and a melt index of 0.22 g/10 min.
~ ~t3~
The ethylelle polymer composit-.on contained 0.3~% by weight of l-butene comonomer, and had a density of 0.955 g/cm .
The ratio of the polymers in -the first and second stages was 50 : 50, and the ethylene copoiymer formed in the second-stage polymerization vessel alone had an intrinsic viscosity ~] of 4.20, and a l-butene content of 0.96% by weight.
The total activity of the catalyst in the first and second steps was 1610 g-poly-mer/millimole of Ti.hr.kg/cm of ethylene pressure.
The resulting ethylene polymer composition obtained by the above method was subjected to a standard testing method for environmental stress cracking de-scribed in ASTM-D-16g3-70 (bent strip method, 25% by weight solution of surfac-tant Antarox* A400) to determine F~o (the time that elapsed until cracking occur-red in 50% of samples, as determined from the logarithmic probability distribu-tion). The F50 of the resulting composition was more than 1000 (i.e., no cracks formed in the samples even after a lapse of more than 1000 hours). TIIUS, the re-sulting ethylene polymer composition had very good resistance -to environmental stress cracking.
Fish eyes of the resulting composition were measured by the following method. It was found that there was hardly any formation of fish eyes, and the fish eyes rating of the composition was 5.
It is seen from the above results that the resulting composition had very good properties for blow molding.
Measurement of fish eyes The composition was pelletized by a pelletizer. Using the resulting pellets, an inflation film, 30 microns thick, was prepared. The film was cut off to a size of 30 cm x 30 cm, and the number of fish eyes was counted. The number was rated as follows.
~ligher ratings show lesser numbers of fish eyes, and thus better quality of the film.
*Trademark - 16 -. ~ ,. . .
: ,, 9~
Number of fish eyes Rating _ .
6 ~ 10 4 31 or more Examples 2 to 13 An ethylene polymer composition was produced in the same way as in Example 1 except that the ratio of the amount of the polymer in the first step to that of the second step, the proportions of the comonomers fed in the first and second steps, the type of the comonomers, and the polymerization conditions were changed as shown in Table 1. The F50 of the resulting ethylene polymer com-position was measured by the me-thod of ASTM-D-1693-70. It was found that in these examples, ethylene polymer compositions having much better resistance to environmental stress cracking than the composi-tions obtained in Comparative Ex-amples were obtained. Moreover, fish eyes hardly formed in molded articles pre-pared from the composition obtained in these Examples. The results are shown in Table 1.
Comparative Example l Example 1 was repeated except that l-butene was copolymerized with ethylene in the firs-t s1:ep to form an ethylcne copolymer having an intrinsic vis-cosity [n] of 1.04, a melt index of 31.0 g/10 min., a density of 0.952 g/cm3 and a l-butene content of 1.04% by weight, and the product was continuously fed into the second-stage polymerization reactor. The ethylene polymer composition con-tinuously discharged from the second-stage polymerization vessel had an intrinsic viscosity [nl of 2.68, a melt index of 0.24 g/lO min. and a density of 0.954 g/cm3. The ethylene polymer formed only in the second-stage polymerization ves-sel had an intrinsic viscosity [n] of 4.32, and did not contain l-butene. The total activity of the catalyst in the first and ; - 17 -,....
second stages was 1~70 g of polymer/millimole of Ti atom.hr.kg/cm2 of ethylene pressure.
The resultillg ethylene polymer composition was tested for resistance to environmental stress cracking by the method of ASTM-D-1693-70, and was found to have an F50 of 28 hours, which was much shorter than those in the Examples.
Comparative Example 2 A 200-liter single-stage continuous polymerization vessel was continu-ously charged with 50 liters/hr of dehydrated and purified hexane, 80 millimoles/
hr of triethyl aluminum, and 1.5 millimoles/hr, calculated as Ti atom, of the supported catalyst obtained in Example 1, and while ciischarging the contents of the polymerization vessel at a predetermined speed, ethylene, l-butene, and hy-drogen were introduced at 80C at a rate of 15.0 kg/hr, 350 g/hr, and 6 Nm3/hr, respectively. Thus, ethylene and l-butene were copolymerized under a total pres-sure of 7 kg/cm .
The ethylene copolymer formed continuously by the polymerization had an intrinsic viscosity [n] of 2.61, a melt index of 0.29 g/10 min., a l-butene content of 0.43% by weight, and a density of 0.953 g/cm . The activity of the catalyst was 1150 g of polymer/millimole of Ti atom.hr.kg/cm of ethylene pres-sure. The resistance to environmental stress cracking of the resuLting ethylene copolymer was examined by the same methocl as ;n Example 1. It was found to have an F50 of 97 hours, shc)wing much inferior stress cracking resistance to that in the Examples.
Comparative Example 3 In the procedure of Example 1, l-butene was fed substantially equally to the first-stage and second-stage polymerizat:ioll vessels. In the first-stage polymerization vessel, an ethylene copolymer having an intrinsic viscosity Ln]
of 1.08, a melt index of 24.0 g/10 min., a density oE 0.959 g/cm3 and a l-butene content `, ' of 0.51% by weight was obtained, and continuously fed into the second-stage poly-merization vessel. The e-thylene polymer composition which continuously flowed out of the second-stage polymerization vessel had an intrinsic viscos;ty [n] of 2.66, a melt index of 0.28 g/10 min., a density of 0.954 g/cm and a 1-butene colltent of 0.50% by weight.
The polymer formed in the second-stage polymerization vessel alone had an intrinsic viscosity [n] of 4.24 and a l-butene content of 0.49% by weight.
The total activity of the catalyst in the first and second stages was 1440 g of polymer/millimole of Ti atom.hr.kg/cm of ethylene pressure.
The environmental stress cracking resistance of the resulting ethylene polymer composition was examined by the same method as in Example 1. It was found to have an F50 of 144 hours, showing inferior stress cracking resistance to that in the Examples.
Comparative Example 4 In the procedure of Examples 12 and 13, l-butene was fed substantially equally to the first-stage and second-stage polymerization vessels. In the first-stage polymerization vessel, an ethylene copolymer having an intrinsic vis-cosity [n] of 0.79, a Melt index of 125 g/10 min., a density of 0.955 g/cm3, and a l-butene content of 5.3% by weight, and was continuously fed into the second-stage polymerization vessel. The ethylene polymer composition which flowed con-tinuously from the second-stage polymerization vessel had an intrinsic viscosity [n] of 3.21, a melt index of 0.10 g/10 min., a l-butene content of 5.3% by weight, and a density of 0.933 g/cm3. The copolymer formed only in the second-stage polymerization vessel had an intrinsic viscosity [n] of 5.63 and a l-butene content of 5.3% by weight. The total activity of the catalyst in the first and second stages was 820 g of polymer/millimole of Ti atom.hr.kg/cm of ethylene pressure.
,.1 r ~ 19 9~
The environmental stress cracking resistance of the resulting ethylene polymer composition was examined by the same method as in Example 1. It was found to have an F50 of 107 hours, showing inferior stress cracking resistance to that in Examples 12 and 13.
Comparative Example 5 In the procedure of Example 1, the polymerization conditions were changed so that the weight ratio of the ethylene polymer formed in the first stage to that formed in the second stage was 72/28. In the first stage, an ethylene polymer free from l-butene was obtained which had an intrinsic viscos-ity [~] of 1.63, a melt index of 3.40 g/10 min. and a density of 0.969 g/cm .
The ethylene polymer was fed continuously to the second-stage polymerization ves-sel. The ethylene polymer composition which flowed out continuously from the second-stage polymerization vessel had an intrinsic viscosity [n] of 2.69, a melt index of 0.25 g/10 min. and a l-butene content of 0.50% by weight. The polymer formed in the second-stage polymerization vessel alone had an intrinsic viscosity [n] of 5.41 and a l-butene content of 1.79~ by weight. The activity of the cat-alyst was 1020 g of polymer/millimole of Ti atom.hr.kg/cm of ethylene pressure.
The resulting ethylene polymer composition had much the same properties as the composition obtained in Example 1.
The environmental stress cracking resistance of the resulting ethylene polymer composition was examined. It was found to have an F50 of 733 hours. But the composition had a fish eye rating of 1, showing that at the time of blow molding, a number of fish eyes occurred in the molded products, and the molded products had no merchandise value.
Comparative Example 6 Synthesis of a catalyst:-Two moles of TiC14 was put into 1 liter of dehydrated and purified ker-osene in a stream of nitrogen, and a-t 0C 2.2 moles of ethyl aluminum sesquichloride was added dropwise with stirring over 2 hollrs. After the addition, the temperature was raised to 60 C
over the course of 1 hour, and the reaction was performed at 60C for 2 hours.
After the reaction, the resulting solid portion was separated by decantation, and repeatedly washed with dehydrated and purified hexane. The concentration of Ti in the hexane suspension was determined by titration. A part of the resulting solid was dried under reduced pressure, and examined for composition. It was found that one gram of the solid contained 185 mg of titanium, 570 mg of Cl and 83 mg of Al.
Polymerization:-The same 200 ml first-stage polymerization vessel as used in Example 1 was continuousLy charged with 25 liters/hr of dehydrated and purified hexane as a solvent, 100 millimo]es/hr of diethyl aluminum chloride and 12.5 millimoles/hr calculated as Ti atom of the solid catalyst prepared as above. While discharging the contents of the polymerization vessel at a predetermined rate, ethylene and hydrogen were introduced into the vessel at 80C at a rate of 8.0 kg/hr, and 14.2 Nm3/hr, respectively. Ethylene was thus contimlously polymerized in the first stage with an average residence time of 4 hours at a total pressure of 8 kg/cm .
The hexane suspension containing polyethylene formed by the polymeriza-tion (ethylene polymer content 300 g/liter, the polyethylene had an intrinsicviscosity of 1.02 and a melt index of 28.5 g/10 min.) was cond~cted to a flush drum at the same temperature as the polymerization temperature, to separate hy-drogen contained in the suspension. The residue was entirely fed into a 200-liter second-stage polymerization vessel, and without additiona]ly supplying the catalyst, purified hexane was fed at a rate of 25 liters/hr. While discharging the contents of the vessel at a predetermined rate, ethylene, l-butene and hydro-gen were introduced into the vessel 3~
at 80C at a rate of 8.0 kg/hr, 360 g/hr, and 0.8 Nm3/hr, respectively. Thus, ethylene was copolymerized with l-butene continuously with a residence time of 2 hours at a total pressure of 8 kg/cm2.
The effluent from the second-stage polymerization contained 300 g/liter.
hr of an ethylene polymer composition. The polymer had an intrinsic viscosity [n] of 2.74 and a melt index of 0.19 g/10 min. The l-butene copolymer was con-tained in the ethylene polymer composition in an amount of 0.49% by weight. The density of the ethylene polymer composition was 0.954 g/cm . The weight ratio of the polymer formed in the first stage to that formed in the second stage was 50 : 50. The ethylene copolymer formed only in the second-stage polymerization vessel had an intrinsic viscosity [n] of 4.46 and a l-butene content of 0.98~ by weight. The total activ;ty of the catalyst in the first and second stages was about 54 g of polymer/millimole of Ti.atom.hr.kg/cm of ethylene pressure. Since the catalyst activity was low, the catalyst had to be removed from the resulting ethylene polymer composition by using methanol.
The environmental stress cracking resistance of the resulting ethylene polymer composition was examined in the same way as in Example 1. It was found to have an F50 of 267 hours, showing inferior stress cracking resistance to that in Example 1. It had a fish eye rating of 3, and a number of fish eyes occurred during blow molding of the resulting composition. The moldecl products were therefore of very low merchandise value.
Comparative Example 7 The polymer obtained in the first stage of Example 1 and the polymer formed in the first stage of Example 6 were separately withdrawn from the poly-merization vessels and dried. The resulting polymers were well mixed in a ratio of 1 : 1 by a Henschel mixer, and pelletized by a pelletizer.
The pellets were molded, and their environmental stress cracking resistance was examined by the method of ASTM-D-1693-70 in the same way as in Example 1. The F50 was 580 hours, and the fish eye rating was 1.
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Compounds having one Al-C bond in the molecule can be used as the organoaluminum compound (B) constituting the catalyst used in this invention.
Examples are (I) organoaluminum compounds of the general formula Rl Al(OR2) H X
(wherein R and R represent a hydrocarbon group such as an alkyl or alkenyl group having 1 to 15 carbon atoms, preferably 1 to 4 carbon atoms, and may be identical or different, X represents halogen, m is a number represented by O<m<3, n is a number represented by O<n<3, p is a number represented by O_p<3, and q is a number represented by O<q<3 with the proviso that m + n ~ p + q = 3);
and (II) complex alkylated products of aluminum and a metal of Group I of the periodic table which is represented by the general formula MlAlR14 (wherein M
represents Li, Na or K, and Rl is the same as defined above).
Examples of the organoaluminum compounds (I) are comE~ollnds of the gen-eral formula Rl Al(OR )3 in which Rl and R2 are as defined above, and m ispreferably a number represented by 1.5<m<3; compounds Or the general formula R AlX3 m wherein Rl is as defined above, X represents a halogen atom, and m is preferably a number represented by O<m<3; compounds represented by the general formula R A1113 wherein R is as defined above, and m is preferably a number represented by 2<m<3; and compounds of the general formula RlmAl(OR ) Xq wherein R and R2 are as defined above, X represents a halogen atom, O<m<3, O<n<3, O<q<3, and m + n + q = 3.
3~
Specific examples of the organoaluminum compounds (I) are trialkyl aluminums such as triethyl aluminum and tributyl aluminum; trialkenyl aluminum such as triisoprenyl aluminum; partially alkoxylated alkyl aluminum, for example, dialkyl aluminum alkoxides such as diethyl aluminum ethoxide and dibutyl aluminum butoxide; alkyl aluminum sesquialkoxides such as ethyl aluminum sesquiethoxide and butyl aluminum sesquibutoxide; dialkyl aluminum halides such as diethyl alum-inum chloride, dibutyl aluminum chloride and diethyl aluminum bromide; alkyl aluminum sesquihalides such as ethyl aluminum sesquichloride, butyl aluminum sesquichloride and ethyl aluminum sesquibromide; partially halogenated alkyl aluminums, for example, alkyl aluminum dihalides such as ethyl aluminum dichlor-ide and propyl. aluminum dichloride; dialkyl aluminum hydrides such as diethyl aluminum hydride and dibutyl aluminum hydride; partially hydrogenated alkyl aluminums, for exampl.e, alkyl aluminum dihydrides such as ethyl aluminum dihy-dride and propyl aluminum dihydride; and partially alkoxylated and halogenated alkyl a].uminums such as ethyl aluminum ethoxychloride, butyl aluminum butoxy-chloride and ethyl aluminum ethoxybromide. As compounds similar to (I), organo-aluminum compounds having at least two aluminum atoms bonded through an oxygen or nitrogen atom may also be used. Examples of such compounds are 2 5)2 (C2H5)2, (C4H9)2AlOAl(c4H9)2 and (C21l5)2AlNA~(c 1-1 ) Examples of the compounds (II) are LiAl(C2H5)4 and LiAl(C7H15)~l.
Among the above-exemplified organoaluminum compounds, trialkyl alum-inums, and alkyl aluminum halides are preferred.
In the process of this i.nvention, an ethylene polymer or an ethylene/
alpha-olefin copolymer havi.ng an alpha-olefin content of up to 15% by weight, preferably up to 10~ by weight, which has an intrinsic viscosity [n]
3~
of 0.3 to 3, preferably 0.4 to 2.5, is formed in step (a). If the alpha-olefin contellt of the coyolymer (i) formed in step (a) exceeds the above-specified upper limit, the resulting chemically blended composition has poor resistance to envi-ronmental stress cracking. If the intrinsic viscosity of the polymer OI' copoly-mer (i) is lower than the above-specified lower limit, the composition has poor processability and molded articles prepared therefrom have marked surface rough-ening. On the other hand, if the intrinsic viscosity of the resulting composi~
tion is lower than the lower limit specified above, the impact strength or tear strength of the resul~ing composition is reduced.
In step (b) of the process of this invention, an ethylene/alpha--olefin copolymer (ii) is formed. The alpha-olefin content of the copolymer (ii) is larger than that of the polymer or copolymer (i), and is 0.2 to 30% by weight, preferably 0.3 to 20% by weight. The intrinsic viscosity of the copolymer (ii) is at least 1.5 times, preferably at least 2 times, that of the polymer or co-polymer (i), and is 1 to 12, preferably 1.5 -to 10.
When the alpha-olefin content and melt index of the copolymer (ii) ob-tained in step (b) are within the above-specified ranges~ the resulting chemical-ly blended composition has markedly improved impact strength and resistance to environmental stress cracking.
The steps (a) and (b) are performed in an optional order. Specifical-ly, step (a) is first performed and then step (b) is performed in the presence of the product of step (a); or step (b) is first performed, and then step (a) is performed in the presence of the product of step (b). In any case, the two steps (a) and (b) should be carried out sequentially. In other words, the polymeriza-tion in the second step must be performed in the presence of the polymerization product of the first step. A chemically blended composition having ., 3~
reduced occurrence of fish eyes is easier to obtain by using in the second step -the catalyst used in the first step, without addiilg a fresh supply of the titan-ium catalyst component in the second step.
In the process of this invention, the polymerization or copolymeriza-tion should also be carried out so that the ratio of the amount of the polymer or copolymer (i) formed in step ~a) to that of the copolymer (ii) formed in step (b) is (30 - less than 60): (above 40 - 70), preferably (40 - 55): (45 - 60) [con-dition (2)]. Furthermore, the polymerization or copolymerization should be car-ried out so that the resulting chemically blended composition has an intrinsic viscosity [n] of 1 to 6 and an alpha~olefin content of 0.2 to 20% by weight [con-dit iOII ( 3)].
By performing the polymerization or copolymerization under a set of conditions (1) to (3) described above, a chemically blended composition of non-elastomeric ethylene resins having the aforesaid improved properties can be formed with a good reproducibility of quality, and this can be achieved even by the slurry polymerization mode.
If the amount of the copolymer (ii) is less than 40% by weight which is outside the range specified in condition (2) above, fish eyes tend to form.
In the practice of the process of this invention, a multi-step process comprising steps (a) and (b) spec:ified above is employed, and the polymerization or copolymerization is carried out under a specified set of conditions (1), (2) and (3). The polymerization or copolymerization itself can be performed by known means.
Thc polymerization or copolymerization may be carried out in the liquid phase or gaseous phase in the presence or absence of an inert solvent. The liq-uid-phase polymerization can be performed in slurry or solution. The process of this invention exhibits marked effec-ts when applied to slurry polymerization or gaseous-. '.
1~3~
phase polymerizatio]l. Examples of inert solvents that can be used in the poly-merizatiorl are aliphatic hydrocarbons such as butane, pentane, hexane, heptane, octane, decane, dodecane and kerosene; alicyclic hydrocarbons such as cyclopent-ane, methylcyclopentane, cyclohexane and methylcyclohexane; and aromatic hydro-carbons such as benzene, toluene, xylene or ethylbenzene.
In performing the liquid-phase polymerization, it is desirable to use about 0.0005 to about l millimole, preferably about 0.001 to about 0.5 millimole, calculated as titanium atom, of the highly active titanium catalyst component (A), and the organoaluminum catalyst component (B) in an aluminum/titanium atomic ratio of from about 1 to about 200, preferably from about 10 to about 500, both per liter of the liquid phase. In performing the gaseous-phase polymerization, it is desirable to use about 0.0005 to a.bout 1 millimole, preferably about 0.001 to about 0.5 millimole, calculated as titanium atom, of the highly active titan-ium catalyst component (A), and the organoaluminum compound in an aluminum/titan-ium atomic ratio of from about 1 to about 2000, preferably from about 10 to 1000, both per liter of the polymerization zone.
In the performance of the process of this invention, the catalyst com-ponents may be additionally fed in the second step, but the titanium catalyst component should preferably not be additionally supplied in the second step.
The suitable polymerization temperature :is about 20 to about 300 C, preferably about 50 to about 200C, and the suitable polymerization pressure is atmospheric pressure to about 100 kg/cm .G, preferably about 2 to about 50 kg/cm .G. The gaseous-phase polymerization can be performed in the same way as in the liquid-phase polymerization except that the polyrnerization temperature is below the temperature at which the polymer melts, especially at about 20 to about 100C. To control , ., ~ ~3~
the intrinsic viscosity [~] of the polymer, hydrogen is preferably utilized.
Examples of the alpha-olefin to be copolymerized with ethylene include propylene, l-butene, l-pentene, l-hexene, 4-methyl-1-pentene, 3-methyl-1-pentene, l-octene, l-decene, l-tetradecene, and l-octadecene. Of these, alpha-olefins having 3 to 10 carbon atoms are preferred.
After the polymerization is over, the resulting chemically blended com-position can be separated in the same way as in the production of polyethylene by an ordinary Ziegler method. In many cases, the product can be used in variousapplication without performing any operation of removing the catalyst. The chem-ically blended ethylene resin composition obtained by the process of this inven-tion is suitable for extrusion molding or blow molding. It has good processabil-ity, and molded products prepared therefrom have high impact strength and high resistance to environmental stress cracking. Moreover, since the molded productshave a substantially reduced number of fish eyes, they are suitable for use as bottles, pipes, films and cable coatings.
The following Examples and Comparative Examples illustrate the process of this invention more specifically.
Example 1 Synthesis of a catalyst Commercial]y available anhydrous magTIesillTll chloride (5 moles) was sus-pended in 10 liters of dehydrated and purified hexane in a stream of nitrogen.
With stirring, 25 moles of ethanol was added dropwise over 1 hour, and the reac-tion was performed for 1 hour at room temperature. Then, 12 moles of diethyl aluminum chloride was added dropwise at room temperature, and the mixture was stirred for 2 hours. Then, 5 moles of titanium tetrachloride was added. The mixture was heated to 60C, and with stirring, reacted for 3 hours. The result-ing solid was separated by decantation, repeatedly washed with purified hexane, and then suspended in hexane. The ~s~
concentration of Ti in the hexane suspension was determined by titration. A
part of the reslllting solid was dried under reduced pressure, and examined for composition. It was found that one gram of the solid contained 72 mg of titan-ium, 205 mg of magnesium and 610 mg of chlorine.
Polymerization A 200 liter first-stage polymerization vessel was charged continuously with 50 liters/hr of dehydrated and purified hexane, 80 millimoles/hr of tri-ethyl aluminum, and 2 millimoles/hr, calculated as Ti atom, of the supported catalyst obtained above. While discharging the contents of the polymerization vessel at a predetermined rate, ethylene and hydrogen were introduced at 80C
into the vessel at a rate of 15.5 kg/hr, and 26 Nm3/hr, respectively. Ethylene was thus polymerized continuously in the first stage with an average residence time of 2 hours at a total pressure of 7 kg/cm .
The hexane suspension containing polyethylene formed by the polymeriza-tion (ethylene polymer content 300 g/liter; intrinsic viscosity [~] of polyethyl-ene 1.10; melt index of the polymer 24.0 g/10 min) was conducted -to a flush drum at the sanne temperature as the polymerization temperature. ~Iydrogen contained in the suspension was separated, and the residue was wholly introduced into a 200 liter second-stage polymerization vessel. Without supplying additional catalyst, purified hexane was fed at a rate of 50 liteIs/hr, arld wh-ile discharging the con-tents of the vessel at a predetermined rate, ethylene, l-butene, and hydrogen were introduced at a rate of 15.5 kg/hr, 600 g/hr, and 1.2 Nm3/hr, respectively.
~hus, ethylene was copolymerized continuously with l-butene in the second stage with a residence time of l hour at a total pressure of 7 kg/cm2.
The effluent from the second-stage polymerization vessel contained 300 g/liter/hr of an ethylene polymer composition. The polymer had an intrinsic viscosity [~] of 2.65 and a melt index of 0.22 g/10 min.
~ ~t3~
The ethylelle polymer composit-.on contained 0.3~% by weight of l-butene comonomer, and had a density of 0.955 g/cm .
The ratio of the polymers in -the first and second stages was 50 : 50, and the ethylene copoiymer formed in the second-stage polymerization vessel alone had an intrinsic viscosity ~] of 4.20, and a l-butene content of 0.96% by weight.
The total activity of the catalyst in the first and second steps was 1610 g-poly-mer/millimole of Ti.hr.kg/cm of ethylene pressure.
The resulting ethylene polymer composition obtained by the above method was subjected to a standard testing method for environmental stress cracking de-scribed in ASTM-D-16g3-70 (bent strip method, 25% by weight solution of surfac-tant Antarox* A400) to determine F~o (the time that elapsed until cracking occur-red in 50% of samples, as determined from the logarithmic probability distribu-tion). The F50 of the resulting composition was more than 1000 (i.e., no cracks formed in the samples even after a lapse of more than 1000 hours). TIIUS, the re-sulting ethylene polymer composition had very good resistance -to environmental stress cracking.
Fish eyes of the resulting composition were measured by the following method. It was found that there was hardly any formation of fish eyes, and the fish eyes rating of the composition was 5.
It is seen from the above results that the resulting composition had very good properties for blow molding.
Measurement of fish eyes The composition was pelletized by a pelletizer. Using the resulting pellets, an inflation film, 30 microns thick, was prepared. The film was cut off to a size of 30 cm x 30 cm, and the number of fish eyes was counted. The number was rated as follows.
~ligher ratings show lesser numbers of fish eyes, and thus better quality of the film.
*Trademark - 16 -. ~ ,. . .
: ,, 9~
Number of fish eyes Rating _ .
6 ~ 10 4 31 or more Examples 2 to 13 An ethylene polymer composition was produced in the same way as in Example 1 except that the ratio of the amount of the polymer in the first step to that of the second step, the proportions of the comonomers fed in the first and second steps, the type of the comonomers, and the polymerization conditions were changed as shown in Table 1. The F50 of the resulting ethylene polymer com-position was measured by the me-thod of ASTM-D-1693-70. It was found that in these examples, ethylene polymer compositions having much better resistance to environmental stress cracking than the composi-tions obtained in Comparative Ex-amples were obtained. Moreover, fish eyes hardly formed in molded articles pre-pared from the composition obtained in these Examples. The results are shown in Table 1.
Comparative Example l Example 1 was repeated except that l-butene was copolymerized with ethylene in the firs-t s1:ep to form an ethylcne copolymer having an intrinsic vis-cosity [n] of 1.04, a melt index of 31.0 g/10 min., a density of 0.952 g/cm3 and a l-butene content of 1.04% by weight, and the product was continuously fed into the second-stage polymerization reactor. The ethylene polymer composition con-tinuously discharged from the second-stage polymerization vessel had an intrinsic viscosity [nl of 2.68, a melt index of 0.24 g/lO min. and a density of 0.954 g/cm3. The ethylene polymer formed only in the second-stage polymerization ves-sel had an intrinsic viscosity [n] of 4.32, and did not contain l-butene. The total activity of the catalyst in the first and ; - 17 -,....
second stages was 1~70 g of polymer/millimole of Ti atom.hr.kg/cm2 of ethylene pressure.
The resultillg ethylene polymer composition was tested for resistance to environmental stress cracking by the method of ASTM-D-1693-70, and was found to have an F50 of 28 hours, which was much shorter than those in the Examples.
Comparative Example 2 A 200-liter single-stage continuous polymerization vessel was continu-ously charged with 50 liters/hr of dehydrated and purified hexane, 80 millimoles/
hr of triethyl aluminum, and 1.5 millimoles/hr, calculated as Ti atom, of the supported catalyst obtained in Example 1, and while ciischarging the contents of the polymerization vessel at a predetermined speed, ethylene, l-butene, and hy-drogen were introduced at 80C at a rate of 15.0 kg/hr, 350 g/hr, and 6 Nm3/hr, respectively. Thus, ethylene and l-butene were copolymerized under a total pres-sure of 7 kg/cm .
The ethylene copolymer formed continuously by the polymerization had an intrinsic viscosity [n] of 2.61, a melt index of 0.29 g/10 min., a l-butene content of 0.43% by weight, and a density of 0.953 g/cm . The activity of the catalyst was 1150 g of polymer/millimole of Ti atom.hr.kg/cm of ethylene pres-sure. The resistance to environmental stress cracking of the resuLting ethylene copolymer was examined by the same methocl as ;n Example 1. It was found to have an F50 of 97 hours, shc)wing much inferior stress cracking resistance to that in the Examples.
Comparative Example 3 In the procedure of Example 1, l-butene was fed substantially equally to the first-stage and second-stage polymerizat:ioll vessels. In the first-stage polymerization vessel, an ethylene copolymer having an intrinsic viscosity Ln]
of 1.08, a melt index of 24.0 g/10 min., a density oE 0.959 g/cm3 and a l-butene content `, ' of 0.51% by weight was obtained, and continuously fed into the second-stage poly-merization vessel. The e-thylene polymer composition which continuously flowed out of the second-stage polymerization vessel had an intrinsic viscos;ty [n] of 2.66, a melt index of 0.28 g/10 min., a density of 0.954 g/cm and a 1-butene colltent of 0.50% by weight.
The polymer formed in the second-stage polymerization vessel alone had an intrinsic viscosity [n] of 4.24 and a l-butene content of 0.49% by weight.
The total activity of the catalyst in the first and second stages was 1440 g of polymer/millimole of Ti atom.hr.kg/cm of ethylene pressure.
The environmental stress cracking resistance of the resulting ethylene polymer composition was examined by the same method as in Example 1. It was found to have an F50 of 144 hours, showing inferior stress cracking resistance to that in the Examples.
Comparative Example 4 In the procedure of Examples 12 and 13, l-butene was fed substantially equally to the first-stage and second-stage polymerization vessels. In the first-stage polymerization vessel, an ethylene copolymer having an intrinsic vis-cosity [n] of 0.79, a Melt index of 125 g/10 min., a density of 0.955 g/cm3, and a l-butene content of 5.3% by weight, and was continuously fed into the second-stage polymerization vessel. The ethylene polymer composition which flowed con-tinuously from the second-stage polymerization vessel had an intrinsic viscosity [n] of 3.21, a melt index of 0.10 g/10 min., a l-butene content of 5.3% by weight, and a density of 0.933 g/cm3. The copolymer formed only in the second-stage polymerization vessel had an intrinsic viscosity [n] of 5.63 and a l-butene content of 5.3% by weight. The total activity of the catalyst in the first and second stages was 820 g of polymer/millimole of Ti atom.hr.kg/cm of ethylene pressure.
,.1 r ~ 19 9~
The environmental stress cracking resistance of the resulting ethylene polymer composition was examined by the same method as in Example 1. It was found to have an F50 of 107 hours, showing inferior stress cracking resistance to that in Examples 12 and 13.
Comparative Example 5 In the procedure of Example 1, the polymerization conditions were changed so that the weight ratio of the ethylene polymer formed in the first stage to that formed in the second stage was 72/28. In the first stage, an ethylene polymer free from l-butene was obtained which had an intrinsic viscos-ity [~] of 1.63, a melt index of 3.40 g/10 min. and a density of 0.969 g/cm .
The ethylene polymer was fed continuously to the second-stage polymerization ves-sel. The ethylene polymer composition which flowed out continuously from the second-stage polymerization vessel had an intrinsic viscosity [n] of 2.69, a melt index of 0.25 g/10 min. and a l-butene content of 0.50% by weight. The polymer formed in the second-stage polymerization vessel alone had an intrinsic viscosity [n] of 5.41 and a l-butene content of 1.79~ by weight. The activity of the cat-alyst was 1020 g of polymer/millimole of Ti atom.hr.kg/cm of ethylene pressure.
The resulting ethylene polymer composition had much the same properties as the composition obtained in Example 1.
The environmental stress cracking resistance of the resulting ethylene polymer composition was examined. It was found to have an F50 of 733 hours. But the composition had a fish eye rating of 1, showing that at the time of blow molding, a number of fish eyes occurred in the molded products, and the molded products had no merchandise value.
Comparative Example 6 Synthesis of a catalyst:-Two moles of TiC14 was put into 1 liter of dehydrated and purified ker-osene in a stream of nitrogen, and a-t 0C 2.2 moles of ethyl aluminum sesquichloride was added dropwise with stirring over 2 hollrs. After the addition, the temperature was raised to 60 C
over the course of 1 hour, and the reaction was performed at 60C for 2 hours.
After the reaction, the resulting solid portion was separated by decantation, and repeatedly washed with dehydrated and purified hexane. The concentration of Ti in the hexane suspension was determined by titration. A part of the resulting solid was dried under reduced pressure, and examined for composition. It was found that one gram of the solid contained 185 mg of titanium, 570 mg of Cl and 83 mg of Al.
Polymerization:-The same 200 ml first-stage polymerization vessel as used in Example 1 was continuousLy charged with 25 liters/hr of dehydrated and purified hexane as a solvent, 100 millimo]es/hr of diethyl aluminum chloride and 12.5 millimoles/hr calculated as Ti atom of the solid catalyst prepared as above. While discharging the contents of the polymerization vessel at a predetermined rate, ethylene and hydrogen were introduced into the vessel at 80C at a rate of 8.0 kg/hr, and 14.2 Nm3/hr, respectively. Ethylene was thus contimlously polymerized in the first stage with an average residence time of 4 hours at a total pressure of 8 kg/cm .
The hexane suspension containing polyethylene formed by the polymeriza-tion (ethylene polymer content 300 g/liter, the polyethylene had an intrinsicviscosity of 1.02 and a melt index of 28.5 g/10 min.) was cond~cted to a flush drum at the same temperature as the polymerization temperature, to separate hy-drogen contained in the suspension. The residue was entirely fed into a 200-liter second-stage polymerization vessel, and without additiona]ly supplying the catalyst, purified hexane was fed at a rate of 25 liters/hr. While discharging the contents of the vessel at a predetermined rate, ethylene, l-butene and hydro-gen were introduced into the vessel 3~
at 80C at a rate of 8.0 kg/hr, 360 g/hr, and 0.8 Nm3/hr, respectively. Thus, ethylene was copolymerized with l-butene continuously with a residence time of 2 hours at a total pressure of 8 kg/cm2.
The effluent from the second-stage polymerization contained 300 g/liter.
hr of an ethylene polymer composition. The polymer had an intrinsic viscosity [n] of 2.74 and a melt index of 0.19 g/10 min. The l-butene copolymer was con-tained in the ethylene polymer composition in an amount of 0.49% by weight. The density of the ethylene polymer composition was 0.954 g/cm . The weight ratio of the polymer formed in the first stage to that formed in the second stage was 50 : 50. The ethylene copolymer formed only in the second-stage polymerization vessel had an intrinsic viscosity [n] of 4.46 and a l-butene content of 0.98~ by weight. The total activ;ty of the catalyst in the first and second stages was about 54 g of polymer/millimole of Ti.atom.hr.kg/cm of ethylene pressure. Since the catalyst activity was low, the catalyst had to be removed from the resulting ethylene polymer composition by using methanol.
The environmental stress cracking resistance of the resulting ethylene polymer composition was examined in the same way as in Example 1. It was found to have an F50 of 267 hours, showing inferior stress cracking resistance to that in Example 1. It had a fish eye rating of 3, and a number of fish eyes occurred during blow molding of the resulting composition. The moldecl products were therefore of very low merchandise value.
Comparative Example 7 The polymer obtained in the first stage of Example 1 and the polymer formed in the first stage of Example 6 were separately withdrawn from the poly-merization vessels and dried. The resulting polymers were well mixed in a ratio of 1 : 1 by a Henschel mixer, and pelletized by a pelletizer.
The pellets were molded, and their environmental stress cracking resistance was examined by the method of ASTM-D-1693-70 in the same way as in Example 1. The F50 was 580 hours, and the fish eye rating was 1.
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Claims (5)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In a process for the production of a chemically blended composition of non-elastomeric ethylene resins in a multiplicity of steps in the presence of a catalyst composed of a transition metal catalyst component and an organometal-lic compound, which comprises (a) a step of forming (i) an ethylene polymer or an ethylene/alphaolefin copolymer having an alpha-olefin content of up to 15% by weight, said polymer or copolymer (i) having an intrinsic viscosity [n] of 0.3 to 3, and (b) a step of forming (ii) an ethylene/alpha-olefin copolymer having an alpha-olefin content of 0.2 to 30% by weight which is more than that of the poly-mer or copolymer (i), said copolymer (ii) having an intrinsic viscosity [n] of 1 to 12 which is at least 1.5 times that of the polymer or copolymer (i), said step (a) being performed first and then step (b) being performed in the presence of the product of step (a), or step (b) being performed first and then step (a) being performed in the presence of the product of step (b); the improvement wherein in steps (a) and (b), ethylene is polymerized or copolymerized with the alpha-olefin (1) in the presence of a catalyst composed of (A) a highly active titanium catalyst component containing titanium, magnesium and halogen and being capable of yielding an ethylene polymer in an amount of at least 250 g/millimole of a titanium atom.hr.kg/cm2 of ethylene pressure and (B) an organoaluminum com-pound, (2) so that the weight ratio of tile polymer or copolymer (i) formed in step (a) to the copolymer (ii) formed in step (b) is (30 - less than 60):
(above 40 - 70), and (3) so that the resulting chemically blended composition has an in-trinsic viscosity [n] of 1 to 6 and an alpha-olefin content of 0.2 to 20% by weight.
(above 40 - 70), and (3) so that the resulting chemically blended composition has an in-trinsic viscosity [n] of 1 to 6 and an alpha-olefin content of 0.2 to 20% by weight.
2. The process of claim 1 wherein the polymerization or copolymerization in steps (a) and (b) is carried out under slurry polymerization conditions.
3. The process of claim 1 wherein the weight ratio of the polymer or copolymer (i) formed in step (a) to the copolymer (ii) formed in step (b) is 40 - 55 to 45 - 60.
4. The process of claim l wherein the ethylene/alpha-olefin copolymer formed in step (a) has an alpah-olefin content of up to 10% by weight and an intrinsic viscosity [n] of 0.4 to 2.5.
5. The process of claim 1 wherein the copolymer (ii) formed in step (b) has an intrinsic viscosity [n] of 1.5 to 10 which is at least 2 times that of the polymer or copolymer (i).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000356263A CA1139488A (en) | 1980-07-15 | 1980-07-15 | Process for production of chemically blended composition of non-elastomeric ethylene resins |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA000356263A CA1139488A (en) | 1980-07-15 | 1980-07-15 | Process for production of chemically blended composition of non-elastomeric ethylene resins |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1139488A true CA1139488A (en) | 1983-01-11 |
Family
ID=4117436
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000356263A Expired CA1139488A (en) | 1980-07-15 | 1980-07-15 | Process for production of chemically blended composition of non-elastomeric ethylene resins |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1139488A (en) |
-
1980
- 1980-07-15 CA CA000356263A patent/CA1139488A/en not_active Expired
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