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
  • C08F210/04—Monomers containing three or four carbon atoms
  • C08F210/06—Propene
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L23/00—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers
  • C08L23/02—Compositions of homopolymers or copolymers of unsaturated aliphatic hydrocarbons having only one carbon-to-carbon double bond; Compositions of derivatives of such polymers not modified by chemical after-treatment
  • C08L23/10—Homopolymers or copolymers of propene
  • C08L23/14—Copolymers of propene
  • C08L23/142—Copolymers of propene at least partially crystalline copolymers of propene with other olefins
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B32—LAYERED PRODUCTS
  • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
  • B32B27/00—Layered products comprising a layer of synthetic resin
  • B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2203/00—Applications
  • C08L2203/16—Applications used for films
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L2314/00—Polymer mixtures characterised by way of preparation
  • C08L2314/02—Ziegler natta catalyst

Definitions

• the present disclosure relates to a polymer compositions comprising a propylene ethylene random copolymer fit for producing films in particular blown and cast films having improved features in particular a reduced number of gels.
• Such kind of polypropylene compositions is widely used for making films in the packaging field, especially in the food packaging field, but also for the packaging non food products and for the production of non-packaging items.
• Packaging examples are the primary packaging of hygienic items, textile articles, magazines, mailing films, secondary collation packaging, shrink packaging films and sleeves, stretch packaging films and sleeves, form-fill-seal packaging films for portioning various types of articles such as bags, pouches or sachets, vacuum formed blisters.
• Examples of form-fill-seal applications are the packaging of peat and turf, chemicals, plastic resins, mineral products, food products, small size solid articles.
• Non packaging items are for example synthetic clothing articles or medical and surgical films, films which are formed into flexible conveying pipes, membranes for isolation and protection in soil, building and construction applications, films which are laminated with non-woven membranes.
• WO 2011/036077 relates to heat-sealable polyolefin films comprising an heterophasic propylene copolymer and a butene- 1 (co)polymer having a content of butene- 1 derived units of 75 wt% or more and a flexural modulus (MEF) of 70 MPa or less.
• a butene- 1 (co)polymer having a content of butene- 1 derived units of 75 wt% or more and a flexural modulus (MEF) of 70 MPa or less.
• WO201 8/211107 relates to a polyolefin composition
• a polyolefin composition comprising a random copolymer of propylene and a polymer of 1 -butene wherein preferably the 1 -butene polymer is a 1 -butene copolymer having a 1 -butene derived units content lower than 50 wt%.
• WO 20110/064131 relates to a polyolefin composition comprising from 70 to 95 wt% of a copolymer of propylene and from 5 to 30 wt% of a butene copolymer having a flexural modulus of 60 MPa or less.
• an object of the present disclosure is a polymer composition
• a polymer composition comprising:
• an object of the present disclosure is a polymer composition
• a polymer composition comprising:
• a Melt Flow Rate measured according to ISO 1133-2011 -(190 °C, 2.16 Kg) ranging from 1.0 to 5.5 g/10 min; preferably from 2.1 to 4.8 g/10 min; more preferably from 2.4 to 4.1 g/10 min;
• Flexural modulus measured according to ISO 178 - 2010 ranging from 50 MPa to 250 MPa; preferably ranging from 80 MPa to 210 MPa; more preferably ranging from 92 MPa, to 174 MPa;
• the melting temperature measured according to Iso 11357-2013 ranging from 83°C and 108 °C, preferably ranging from 84°C and 103 °C; more preferably ranging from 88°C and 100 °C, form I; the sum of the amounts of A) and B) being 100 wt%.
• copolymer refers to polymers containing only two comonomers such as propylene and ethylene or 1 -butene and ethylene or propylene and 1 -butene.
• the relative content of isolated to block ethylene sequences 1(E) is higher than 60. 1 ; preferably higher than 65.0; more preferably higher than 68.0; even more preferably higher than 70.1;
• 1(E) is the relative content of isolated to block ethylene sequences (%); PEP is the mol fraction of propylene/ethylene sequences in the sample; PEE is the mol fraction of propylene/ethylene sequences in the sample; EEE is the mol fraction of propylene/ethylene sequences in the sample and wherein all sequence concentrations being based on a statistical triad analysis of 13 C-NMR data.
• the melting point, Tm and the ethylene content wt% C2 fulfills the following relation:
• the 1(E) is the relative content of isolated to block ethylene sequences (%) and is an indication of the randomness of the polymer.
• random is referred to a propylene ethylene copolymer having (IE) higher than 65.0 %.
• the 2, 1 insertion are not detectable at the 13 C NMR spectra acquired on a Bruker AV-600 spectrometer equipped with cryoprobe, operating at 160.91 MHz as described in the examples.
• Random Propylene ethylene copolymer (A) does not contain propylene homopolymer fraction.
• Random Propylene ethylene copolymer (A) is preferably obtained with a process being carried out in a reactor having two interconnected polymerization zones, a riser and a downcomer, wherein the growing polymer particles:
• fast fluidization conditions are established by feeding a gas mixture comprising one or more alpha-olefins at a velocity higher than the transport velocity of the polymer particles.
• the velocity of said gas mixture is generally comprised between 0.5 and 15 m/s, preferably between 0.8 and 5 m/s.
• transport velocity and fast fluidization conditions are well known in the art; for a definition thereof, see, for example, "D. Geldart, Gas Fluidisation Technology, page 155 et seq., J. Wiley & Sons Ltd., 1986".
• the polymer particles flow under the action of gravity in a densified form, so that high values of density of the solid (mass of polymer per volume of reactor) are achieved, said density of solid approaching the bulk density of the polymer.
• a densified form of the polymer implies that the ratio between the mass of polymer particles and the reactor volume is higher than 80% of the "poured bulk density” of the obtained polymer.
• the "poured bulk density" of a polymer is a parameter well known to the person skilled in the art. In view of the above, it is clear that in the downcomer the polymer flows downward in a plug flow and only small quantities of gas are entrained with the polymer particles.
• the recycle gas stream is generally withdrawn from a gas/solid separator placed downstream the riser, cooled by passage through an external heat exchanger and then recycled to the bottom of the riser.
• the recycle gas stream comprises, besides the gaseous monomers, also the inert polymerization components, such as propane, and chain transfer agents, such as hydrogen.
• the composition of the barrier stream deriving from condensation and/or distillation of the gas recycle stream may be suitably adjusted by feeding liquid make-up monomers and propane before its introduction into the upper part of downcomer.
• the operating parameters of temperature and pressure are those that are usual in gas-phase catalytic polymerization processes.
• the temperature is generally comprised between 60°C and 120°C, while the pressure can range from 5 to 40 bar.
• the process for preparing the propylene ethylene copolymer of the present disclosure is carried out in presence of a highly stereospecific heterogeneous Ziegler-Natta catalyst.
• the Ziegler-Natta catalysts suitable for producing the propylene ethylene copolymer of the disclosure comprise a solid catalyst component comprising at least one titanium compound having at least one titanium-halogen bond and at least an electron-donor compound (internal donor), both supported on magnesium chloride.
• the Ziegler-Natta catalysts systems further comprise an organo-aluminum compound as essential co-catalyst and optionally an external electron-donor compound.
• the organo-aluminum compound is preferably an alkyl-Al selected from the trialkyl aluminum compounds such as for example triethylaluminum, triisobutylaluminum, tri-n- butylaluminum, tri-n-hexylaluminum, tri-n-octylaluminum. It is also possible to use mixtures of trialkylaluminum's with alkylaluminum halides, alkylaluminum hydrides or alkylaluminum sesqui chlorides such as AlEt2Cl and AhEtsCh.
• Preferred external electron-donor compounds include silicon compounds, ethers, esters such as ethyl 4-ethoxybenzoate, amines, heterocyclic compounds and particularly 2, 2,6,6- tetramethyl piperidine, ketones and the 1,3 -di ethers.
• Another class of preferred external donor compounds is that of silicon compounds of formula Ra 5 Rb 6 Si(OR 7 ) c where a and b are integer from 0 to 2, c is an integer from 1 to 3 and the sum (a+b+c) is 4; R 5 , R 6 , and R 7 , are alkyl, cycloalkyl or aryl radicals with 1-18 carbon atoms optionally containing heteroatoms.
• methylcyclohexyldimethoxysilane diphenyldimethoxysilane, methyl-t-butyldimethoxysilane, di cyclopentyldimethoxysilane, 2-ethylpiperidinyl-2-t-butyldimethoxysilane and 1,1,1 ,trifluoropropyl-2-ethylpiperidinyl-dimethoxysilane and 1,1,1 ,trifluoropropyl-metil- dimethoxysilane.
• the external electron donor compound is used in such an amount to give a molar ratio between the organo-aluminum compound and said electron donor compound of from 0.1 to 500; preferably from 1 to 100; more preferably from 2 to 50.
• Component B) is known in the art it is a 1 -butene ethylene copolymer commercially available, such as Koattro DP 8310M sold by LyondellBasell.
• the polymer composition of the present disclosure can be prepared by mechanically blending component A) and component B) in accordance with processes well known in the art.
• the polymer composition of the present disclosure can be advantageously used for the preparation of films, in particular cast and blow films.
• a further object of the present disclosure is a film comprising the polymer composition of the present disclosure in particular a further object of the present disclosure is a cast film or a blow film comprising the polymer composition of the present disclosure.
• the polymer composition of the present disclosure can further contain additives used in the art.
• the polymer composition of the present disclosure can be advantageously used as sealing layer in a multilayer film, it allows to seal the film at lower temperature.
• the polymer composition of the present invention has a very low seal initiation temperature (SIT).
• SIT seal initiation temperature
• the seal initiation temperature measured as reported in the examples, fulfils the following relation (III):
• SIT(A) is the value of the seal initiation temperature of component (A) alone;
• CB is the amount (wt%) of component B.
• the polymer composition of the present disclosure consists essentially of components A) and B) as above described.
• the term “consists essentially of’ means that specific further components can be present, namely those not materially affecting the essential characteristics of the compound or composition. In particular no further polymers in particular polyolefins are present in the composition.
• Xylene Solubles at 25°C have been determined according to ISO 16 152; with solution volume of 250 ml, precipitation at 25°C for 20 minutes, 10 of which with the solution in agitation (magnetic stirrer), and drying at 70°C.
• Melting point has been measured according to ISO 11357-3, at scanning rate of 20C/min both in cooling and heating, on a sample of weight between 5 and 7 mg., under inert N2 flow. Instrument calibration made with indium
• I(E) (PEP/[EEE+PEE+PEP])xl00;
• the tacticity of Propylene sequences was calculated as mm content from the ratio of the PPP mmTpp (28.90-29.65 ppm) and the whole Tpp (29.80-28.37 ppm).
• Determination of the regioinvertions determined by means of C 13 -NMR according to the methodology described by J.C. Randall in "Polymer sequence determination Carbon 13 NMR method", Academic Press 1977.
• the content of regioinvertions is calculated on the basis of the relative concentration of S a p + Spp methylene sequences.
• the content of comonomers was determined by infrared spectroscopy by collecting the IR spectrum of the sample vs. an air background with a Fourier Transform Infrared spectrometer (FTIR).
• FTIR Fourier Transform Infrared spectrometer
• C2 and 1-butene (C4) contents were used to calculate ethylene (C2) and 1-butene (C4) contents: a) Area (At) of the combination absorption bands between 4482 and 3950 cm’ 1 which is used for spectrometric normalization of film thickness. b) Area (Ac2) of the absorption band due to methylenic sequences (CH2 rocking vibration) in the range 660 to 790 cm’ 1 after a proper digital subtraction of an isotactic polypropylene (IPP) and a C2C4 references spectrum.
• IPP isotactic polypropylene
• the factor of subtraction (FCRc4) between the spectrum of the polymer sample and the C2C4 reference spectrum The reference spectrum is obtained by digital subtraction of a linear polyethylene from a C2C4 copolymer, in order to extract the C4 band (ethyl group at -771 cm-1).
• the ratio Ac2 / At is calibrated by analyzing ethylene- 1 -butene standard copolymers of known compositions, determined by NMR spectroscopy. In order to calculate the ethylene (C2) and 1 -butene (C4) content, calibration curves were obtained by using samples of known amount of ethylene and 1 -butene detected by 13 C-NMR.
• the 1 -butene content (% molar fraction C4m) of the sample was calculated as follows: ac4, bc4, cc4 ac2, bc2, cc2 are the coefficients of the two calibrations.
• Some films with a thickness of 50 pm are prepared by extruding each test composition in a a single screw Collin extruder (length/diameter ratio of screw 1 :25) at a film drawing speed of 7 m/min and a melt temperature do 210-250 °C.
• Each resulting film is superimposed on a 1000 pm thick film of a propylene homopolymer having a xylene insoluble fraction of 97 wt% and a MFR L of 2 g/10 min.
• the superimposed films are bonded to each other in a Carver press at 200°C under a 9000 kg load, which is maintained for 5 minutes.
• the resulting laminates are stretched longitudinally and transversally, i.e. biaxially, by a factor 7 with a Karo 4 Brueckener film stretcher at 160°C, thus obtaining a 20 pm thick film (18 pm homopolymer+2 pm test).
• Temperature variation must be adjusted stepwise, if seal strength is close to target select steps of 1°C if the strength is far from target select steps of 2°C.
• the target seal strength (SIT ) is defined as the lowest temperature at which a seal strength higher or equal to 1.5 N is achieved.
• Cylinders 200 (close to the hopper) -> 230°C (at the end of the extruder, before the inlet to the die) Die 240°C
• the Ziegler-Natta catalyst was prepared according to Example 5, lines 48-55, of the European Patent EP728769B 1.
• the solid catalyst component described above is contacted with aluminum-triethyl (TEAL) and with the dicyclopentyldimethoxysilane (D donor) under the conditions reported in Table 1.
• TEAL aluminum-triethyl
• D donor dicyclopentyldimethoxysilane
• the catalyst system is then subject to prepolymerization treatment at 20°C by maintaining it in suspension in liquid propylene for a residence time of 9 minutes before introducing it into the polymerization reactor.
• the polymerization was carried out in gas-phase polymerization reactor comprising two interconnected polymerization zones, a riser and a downcomer, as described in European Patent EP782587. Hydrogen was used as molecular weight regulator.
• the polymer particles exiting from the polymerization step were subjected to a steam treatment to remove the unreacted monomers and dried under a nitrogen flow.
• Component B is a commercial product sold by Lyondelbasell under the tradename Koattro DP 8310M.

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• Crystallography & Structural Chemistry (AREA)
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