Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/16—Copolymers of ethene with alpha-alkenes, e.g. EP rubbers
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F210/00—Copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond
  • C08F210/04—Monomers containing three or four carbon atoms
  • C08F210/06—Propene

Definitions

• the present invention relates to a polypropylene random copolymer endowed with some features especially suitable for injection molding application and for melt blown and compounding applications.
• Polypropylene random copolymer has been used for several years for casting cups and molds.
• a polypropylene having a melt flow rate lower than 100 g/10 min is described for injection molding in particular for the obtainment of contact lenses and other precision application.
• an object of the present invention is a polypropylene resin comprising a propylene copolymer said polypropylene resins is endowed with the following features: a) a propylene copolymer having a melt flow rate (MFR) (ISO 1133) (230°C/2.16 kg) comprised between 90 and 3000 g/10', preferably between 120 and 3000 g/10' and more preferably between 130 and 2500 g/10' measured on the powder; b) distribution of molecular weight MwMn lower than 4; preferably lower than 3; more preferably lower than 2.5; c) hexane extractables determined according FDA regulations of less than 2.6 wt.%, more preferred less than 2,0 wt.% even more preferred less than 1.7 wt.% and most preferred less than 1 wt.% d) xylene solubles of less than 2.2 wt.%, more preferred less than 1.7 wt.% e) isotactic pentads (
• a propylene copolymer having a melting point measured by DSC higher than 130 0 C, preferably between 135 and 153°C more preferably between 139 and 153°C and even more preferably between 145°C and 153°C measured on the powder; with the proviso that the propylene copolymer was not visbroken.
• the process for visbreaking a polymer consists in increasing the MFR of the latter by lowering the molecular weight of the polymers by means of chemical reactions such as radical reaction initiated by peroxides.
• the polymers obtained in this way presents some drawback, such as an high yellowing index, for this reason the polypropylene resin object of the present invention does not contains residues of peroxidic compounds.
• the polypropylene resin of the object of the present invention is further endowed with the following features: g) haze measured according to ASTM D 1003 (lmm placque) comprised between 5% and 25%; preferably between 7% and 20%; more preferably between 7% and 15%; h) flexural modulus measured according ISO 178 comprised between 1100 N/m and 2000 N/m ; preferably comprised between 1200 N/m and 2000 Nm and most preferably between 1350 N/m 2 and 2000 N/m 2 .
• the polypropylene resins having a MFR value between 90 and 500 g/10' at 230 0 C have at a shear rate of 100 1/s at 250 0 C a viscosity between 100 Pas and 11 Pas, more preferred between 80 Pas and 11 Pas and most preferably between 50 Pas and 11 Pas
• the polypropylene resins having a MFR value higher than 500 g/10' at 230 0 C of the present invention have at a shear rate of 1500 1/s at 250 0 C a viscosity between 11 Pas and 1 Pas, more preferred between 10 Pas and 1 Pas and most preferably between 7 Pas and 1 Pas
• the propylene copolymer of the present invention has preferably a content of 2,1 -insertions lower than 0.5%, more preferred ⁇ 0.3 %. measured by C NMR spectroscopy. The content of 1,3 insertions is preferably below 0.2 % , more preferred ⁇ 0.1 %.
• the comonomers used in the propylene copolymers are ethylene or 1 -butene.
• the amount of comonomer in the propylene copolymer ranges preferably from 0.1% to 4% by mol, more preferably from 0. 1% by mol to 3% by mol.
• the polypropylene resin of the present invention preferably further comprises customary amounts of customary additives known to those skilled in the art, e.g.
• Customary stabilizers include antioxidants such as sterically hindered phenols, sterically hindered amines or UV stabilizers, processing stabilizers such as phosphites or phosphonites, acid scavengers such as calcium stearate or zinc stearate or dihydrotalcite, as well as calcium, zinc and sodium caprylate salts.
• the propylene copolymer compositions of the present invention contain one or more stabilizers in amounts of up to 2% by weight.
• Suitable lubricants and mold release agents are, for example, fatty acids, calcium, sodium or zinc salts of fatty acids, fatty acid amides or low molecular weight polyolefin waxes, which are usually used in concentrations of up to 2% by weight.
• Possible fillers are, for example, talc, calcium carbonate, chalk or glass fibers, and these are usually used in amounts of up to 50% by weight.
• nucleating agents examples include inorganic additives such as talc, silica or kaolin, salts of monocarboxylic or polycarboxylic acids, e.g. sodium benzoate or aluminum tert- butylbenzoate, dibenzylidenesorbitol or its Ci-Cs-alkyl-substituted derivatives such as methyldibenzylidenesorbitol, ethyldibenzylidenesorbitol or dimethyldibenzylidenesorbitol or salts of diesters of phosphoric acid, e.g. sodium 2,2'-methylenebis(4,6,-di-tert- butylphenyl)phosphate.
• the nucleating agent content of the propylene copolymer composition is generally up to 5% by weight.
• Such additives are generally commercially available and are described, for example, in Gachter/M ⁇ ller, Plastics Additives Handbook, 4th Edition, Hansa Publishers, Kunststoff, 1993.
• MFR of the polypropylene resin of the present invention is lower than 200 g/10' it can contain from 0.03 to 1 % by weight, preferably from 0.05 to 0.25% by weight, of a nucleating agent, in particular dibenzylidenesorbitol or a dibenzylidenesorbitol derivative, particularly preferably dimethyldibenzylidenesorbitol.
• glyceryl monostearate (tradenames for these products are Loxiol EP 55, Atmer 122, Baerolub MS 90 or Atmer 129) is preferred in the present invention.
• the range contains from 0.05% by weight to 0.6% by weight, more preferred from 0.1% to 0.4% by weight.
• the polypropylene resin object of the present invention is particularly suitable to be used for injection molding.
• the polypropylene resin of the present invention can be advantageously used for obtaining cups or other similar tools.
• the value of IZOD at low temperature (0 0 C) makes the resin of the present invention particularly suitable for injection molding applications
• a further object of the present invention is the use of the propylene resin described above for the production of molded articles.
• a further object of the present invention are molded article obtained by using the propylene resin objectof the present invention.
• the random propylene copolymer of the propylene resin object of the present invention can be obtained by using a metallocene -based catalyst system.
• propylene copolymer is obtainable by using a catalyst system obtainable by contacting: a) a metallocene compound of formula (I)
• M is a transition metal belonging to group 3, 4, 5, 6 or to the lanthanide or actinide groups in the Periodic Table of the Elements; preferably M is titanium, zirconium or hafnium; X, same or different, is a hydrogen atom, a halogen atom, or a R, OR, OSO 2 CF 3 , OCOR, SR, NR 2 or PR 2 group, wherein R is a are linear or branched, cyclic or acyclic, Ci-C 4 o-alkyl, C2-C40 alkenyl, C2-C40 alkynyl, C6-C4o-aryl, C7-C4o-alkylaryl or C7-C4o-arylalkyl radicals; optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements; preferably R is a linear or branched Ci-C 2 o-alkyl radical; or two X can optionally form a substituted or unsubsti
• R 1 and R 5 are a C 1 -C 4 0 hydrocarbon radical optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements; preferably R 1 and R 5 are linear or branched, cyclic or acyclic, Ci-C 4 o-alkyl, C 2 -C 4 o alkenyl, C 2 -C 4 o alkynyl, C6-C 4 o-aryl, C 7 -C 4 o-alkylaryl or C 7 -C 4 o-arylalkyl radicals; optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table of the Elements; more preferably R 1 and R 5 are a linear or branched, saturated or unsaturated Ci-C 2 o-alkyl radical; R 2 , R 3 and R 4 , equal to or different from each other, are hydrogen atoms or C 1 -C 4 0 hydrocarbon radicals optionally containing heteroatoms belonging to groups 13-17 of the Periodic Table
• the substituent R is a linear Ci-C 2 o-alkyl radical such as methyl or ethyl radicals and the substituent R 5 is a branched Ci-C 2 o-alkyl radical, preferably the substituent R 5 is a branched Ci-C 2 o-alkyl radical wherein the carbon atom in the alpha position is a secondary or a tertiary carbon atom, such as an isopropyl radical.
• Alumoxanes used as component b) in the catalyst system according to the present invention can be obtained by reacting water with an organo-aluminium compound of formula H J A1U 3 _ J or H j Al 2 Ue -) , where the U substituents, same or different, are hydrogen atoms, halogen atoms, Ci-C 2 o-alkyl, C3- C 20 -cyclalkyl, Co-C 2 o-aryl, C 7 -C 2 o-alkylaryl or C 7 -C 2 o-arylalkyl radicals, optionally containing silicon or germanium atoms, with the proviso that at least one U is different from halogen, and j ranges from O to 1 , being also a non-integer number.
• the molar ratio of Al/water is preferably comprised between 1:1 and 100:1.
• alumoxanes used in the process according to the invention are considered to be linear, branched or cyclic compounds containing at least one group of the type:
• n 1 is 0 or an integer of from 1 to 40 and the substituents U are defined as above; or alumoxanes of the formula:
• (Al- O) n 2 can be used in the case of cyclic compounds, wherein n is an integer from 2 to 40 and the U substituents are defined as above.
• alumoxanes suitable for use according to the present invention are methylalumoxane
• MAO tetra-(isobutyl)alumoxane
• TIBAO tetra-(isobutyl)alumoxane
• TIOAO tefra-(2,4,4-trimethyl-pentyl)alumoxane
• TDMBAO tefra-(2,3-dimethylbutyl)alumoxane
• Non-limiting examples of aluminium compounds that can be reacted with water to give suitable alumoxanes (b), described in WO 99/21899 and WO01/21674, are: fris(2,3,3-trimethyl-butyl)aluminium, tris(2,3-dimethyl-hexyl)aluminium, tris(2,3-dimethyl- butyl)aluminium, tris(2,3-dimethyl-pentyl)aluminium, tris(2,3-dimethyl-heptyl)aluminium, tris(2 -methyl-3 -ethyl-pentyl)aluminium, tris(2 -methyl-3 -ethyl-hexyl)aluminium, tris(2 -methyl-3 - ethyl-heptyl)aluminium, tris(2 -methyl-3 -propyl-hexyl)aluminium, tris(2-ethyl-3
• TMA trimethylaluminium
• TIBA triisobutylaluminium
• TIOA tris(2,4,4-trimethyl-pentyl)aluminium
• TDMBA tris(2,3-dimethylbutyl)aluminium
• TTMBA tris(2,3,3-trimethylbutyl)aluminium
• Non-limiting examples of compounds able to form an alkylmetallocene cation are compounds of formula D + E " , wherein D + is a Br ⁇ nsted acid, able to donate a proton and to react irreversibly with a substituent X of the metallocene of formula (I) and E " is a compatible anion, which is able to stabilize the active catalytic species originating from the reaction of the two compounds, and which is sufficiently labile to be removed by an olefinic monomer.
• the anion E " comprises one or more boron atoms.
• the anion E " is an anion of the formula BAr 4 , wherein the substituents Ar which can be identical or different are aryl radicals such as phenyl, pentafluorophenyl or bis(trifluoromethyl)phenyl. Tetrakis-pentafluorophenyl borate is particularly preferred compound, as described in WO 91/02012.
• compounds of formula BAr 3 can be conveniently used. Compounds of this type are described, for example, in the International patent application WO 92/00333. Other examples of compounds able to form an alkylmetallocene cation are compounds of formula BAr 3 P wherein P is a substituted or unsubstituted pyrrol radical.
• Non limiting examples of compounds of formula D + E " are:
• Organic aluminum compounds used as compound c) are those of formula H j AlU3- j or H J AI 2 UO- ) as described above.
• the catalysts described above can also be supported on an inert carrier. This is achieved by depositing the metallocene compound a) or the product of the reaction thereof with the component b), or the component b) and then the metallocene compound a) on an inert support such as, for example, silica, alumina, Al-Si, Al-Mg mixed oxides, magnesium halides, styrene/divinylbenzene copolymers, polyethylene or polypropylene.
• an inert support such as, for example, silica, alumina, Al-Si, Al-Mg mixed oxides, magnesium halides, styrene/divinylbenzene copolymers, polyethylene or polypropylene.
• the supportation process is carried out in an inert solvent such as hydrocarbon for example toluene, hexane, pentane or propane and at a temperature ranging from 0 0 C to 100 0 C, preferably the process is carried out at room temperature.
• an inert solvent such as hydrocarbon for example toluene, hexane, pentane or propane
• a suitable class of supports which can be used is that constituted by porous organic supports functionalized with groups having active hydrogen atoms. Particularly suitable are those in which the organic support is a partially crosslinked styrene polymer. Supports of this type are described in European application EP-633 272.
• inert supports particularly suitable for use according to the invention is that of polyolefm porous prepolymers, particularly polyethylene.
• a further suitable class of inert supports for use according to the invention is that of porous magnesium halides such as those described in International application WO 95/32995.
• the solid compound thus obtained, in combination with the further addition of the alkylaluminium compound either as such or prereacted with water if necessary, can be usefully employed in the gas- phase polymerization.
• the mmmm content was obtained modelling the experimental pentad distribution with the enantiomorphic site model.
• [H] 100 (0.5 H 2 / ⁇ [CH2]) where E 9 is the peak at 42.14 ppm, H2 is the peak at 30.82 ppm and ⁇ [CH2] is the sum of all
• Calibration is obtained by analyzing propylene/ethylene standard copolymers.
• the film thickness is determined according to the following table.
• the IR spectra is then recorded by using a FTIR apparatus.
• the ethylene content is then calculated according to the following formula
• G is the slope of the calibration straight line
• A is the area of the band due to the methylenic sequences vs. a baseline plotted between the ends of the 790-660 cm " range, after subtraction of the isotactic polypropylene reference spectrum from the sample spectrum in the same spectral range.
• a calibration curve was obtained using 10 polystyrene standard samples (EasiCal kit by Polymer Laboratories) with molecular weights in the range from 580 to 7500000; additionally two other standards with peak molecular weight of 11600000 and 13200000 from the same manufacturer were included. It was assumed that the K values of the Mark-Houwink relationship were:
• Intrinsic viscosity was measured in tetrahydronaphtalene (THN) solution obtained by dissolving the polymer at 135°C for 1 hour.
• hexane extractables of the rancomcopolymers were measured under the same conditions used for homopolymers ( hexane under reflux)
• the ISO norm describes the procedure of measuring the MFR values til 150 g/10'.
• Capillary Rheometer at 3 differerent temperatures 200 0 C, 230 0 C and 250 0 C.
• the catalyst system is prepared as described in PCT/EP2004/007061 by using rac- dimethylsilylene(2-methyl-4(4'tertbutyl-penhyl)-indenyl) (2-isopropyl-4(4'tertbutyl-penhyl)- indenyl)zirconium di chloride prepared as described in US 2003/0149199 instead of rac- dimethylsilylbis(2-methyl-4, 5-benzo-indenyl)-zirconium dichloride.
• the catalyst system in the form of catalyst mud obtained as described in PCT/EP2004/007061 is fed in the precontact vessel in which it is diluted with about 5 (Kg/h) of propane. From the pre- contact vessel the catalyst system is fed to the prepolymerization loop in which propylene is fed at the same time according to the data reported in table 1. The residence time of the catalyst in the prepolymerization loop is about 8 minutes.
• the prepolymerized catalyst obtained in the prepolymerization loop is then continuously feed into the first loop reactor wherein propylene, ethylene and hydrogen were feed according to table 1 .
• the polymer is discharged from the first loop reactor, separated from the unreacted monomer and dried.
• the reaction conditions are reported in table 1.
• the MFR of the product is controlled via the feed of hydrogen.
• Example 1 MFR 150 g/10', 1.5 wt.% ethylene content (IR)
• Example 2 MFR 110 g/ 10 ' , 1.8 wt.% ethylene content (IR)
• Example 3 MFR 132 g/10', 2.3 wt.% ethylene content (IR)
• the pelletized material was injection moulded (ISO 1873/2).
• the production of the test specimens required for use related tests and the tests themselves were carried out in accordance with the standards indicated in table 3
• the ethylene content of Example 4 was lwt.%, the ethylene content of example 5 1,5 wt.%.
• melt viscosity was determined according ISO 11443 at three different temperatures (200 0 C; 230 0 C and 250 0 C) (table 4 and table 5) Table 4:
• Comparative Example 8 MFR 8 g/10' , 1.6 wt.% ethylene content (IR)
• the pelletized material was injection moulded (ISO 1873/2).
• the production of the test specimens required for use related tests and the tests themselves were carried out in accordance with the standards indicated in table 8 :
• the isotactic pentades (mmmm) of the polymer of comparative examples 10 and 1 1 are higher than 95 %.
• the 2.1 insertions are ⁇ 0.3% and the 1.3 insertions ⁇ 0.1
• Comparative Example 10 is a Random copolymer with the same melting point as Example 4 but lower MFR.
• the stiffness of comparative example 10 is lower than the stiffness of Example 4.
• Comparative Example 11 represents a homopolymer at a high MFR of
• Example 12 MFR 1225 g/10', 2.3 wt.% ethylene content (IR)
• Example 13 MFR 1307 g/10', 1.6 wt.% ethylene content (IR)
• Example 14 MFR 1670 g/10' 1.3 wt.% ethylene content (IR)
• Example 12 The powder of Example 12, Example 13 and Example 14 was characterized in powder form (table 12):
• the isotactic pentades (mmmm) of the polymer of examples 12-14 are higher than 95 %.
• the 2.1 insertions are ⁇ 0.3% and the 1.3 insertions ⁇ 0.1
• the melt viscosity was determined according ISO 11443 at three different temperatures (200 0 C; 230 0 C and 250 0 C) (table 11 and table 12 for example 12 and example 13).

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• 2006
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