MXPA01000148A - Polyethylene compositions having improved optical and mechanical properties and improved processability in the melted state - Google Patents
Polyethylene compositions having improved optical and mechanical properties and improved processability in the melted stateInfo
- Publication number
- MXPA01000148A MXPA01000148A MXPA/A/2001/000148A MXPA01000148A MXPA01000148A MX PA01000148 A MXPA01000148 A MX PA01000148A MX PA01000148 A MXPA01000148 A MX PA01000148A MX PA01000148 A MXPA01000148 A MX PA01000148A
- Authority
- MX
- Mexico
- Prior art keywords
- ethylene
- copolymers
- chr
- alpha
- propylene
- Prior art date
Links
- 239000000203 mixture Substances 0.000 title claims abstract description 39
- -1 Polyethylene Polymers 0.000 title claims abstract description 23
- 239000004698 Polyethylene (PE) Substances 0.000 title claims abstract description 19
- 229920000573 polyethylene Polymers 0.000 title claims abstract description 19
- 230000003287 optical Effects 0.000 title description 10
- 239000005977 Ethylene Substances 0.000 claims abstract description 22
- VGGSQFUCUMXWEO-UHFFFAOYSA-N ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 claims abstract description 22
- 239000004711 α-olefin Substances 0.000 claims abstract description 15
- 229920005606 polypropylene copolymer Polymers 0.000 claims abstract description 11
- 229920001577 copolymer Polymers 0.000 claims description 25
- 229920001684 low density polyethylene Polymers 0.000 claims description 7
- 239000004702 low-density polyethylene Substances 0.000 claims description 7
- CTQNGGLPUBDAKN-UHFFFAOYSA-N o-xylene Chemical compound CC1=CC=CC=C1C CTQNGGLPUBDAKN-UHFFFAOYSA-N 0.000 claims description 6
- 238000005429 turbidity Methods 0.000 claims description 6
- 239000008096 xylene Substances 0.000 claims description 6
- 125000004432 carbon atoms Chemical group C* 0.000 claims description 4
- 239000010410 layer Substances 0.000 claims description 3
- 239000002365 multiple layer Substances 0.000 claims description 2
- 229920000092 linear low density polyethylene Polymers 0.000 abstract description 19
- 239000004707 linear low-density polyethylene Substances 0.000 abstract description 19
- 239000003054 catalyst Substances 0.000 description 16
- 238000000034 method Methods 0.000 description 8
- 229920000642 polymer Polymers 0.000 description 7
- VXNZUUAINFGPBY-UHFFFAOYSA-N 1-butene Chemical compound CCC=C VXNZUUAINFGPBY-UHFFFAOYSA-N 0.000 description 6
- 238000006116 polymerization reaction Methods 0.000 description 6
- 150000001875 compounds Chemical class 0.000 description 5
- 241000424123 Trachinotus baillonii Species 0.000 description 4
- 230000000875 corresponding Effects 0.000 description 4
- 238000002156 mixing Methods 0.000 description 4
- 238000002360 preparation method Methods 0.000 description 4
- 210000001138 Tears Anatomy 0.000 description 3
- 125000004805 propylene group Chemical group [H]C([H])([H])C([H])([*:1])C([H])([H])[*:2] 0.000 description 3
- LIKMAJRDDDTEIG-UHFFFAOYSA-N 1-Hexene Chemical compound CCCCC=C LIKMAJRDDDTEIG-UHFFFAOYSA-N 0.000 description 2
- TWRXJAOTZQYOKJ-UHFFFAOYSA-L MgCl2 Chemical compound [Mg+2].[Cl-].[Cl-] TWRXJAOTZQYOKJ-UHFFFAOYSA-L 0.000 description 2
- YWAKXRMUMFPDSH-UHFFFAOYSA-N Pentene Chemical compound CCCC=C YWAKXRMUMFPDSH-UHFFFAOYSA-N 0.000 description 2
- 238000007792 addition Methods 0.000 description 2
- 239000001273 butane Substances 0.000 description 2
- 238000000113 differential scanning calorimetry Methods 0.000 description 2
- 229920001971 elastomer Polymers 0.000 description 2
- 239000000806 elastomer Substances 0.000 description 2
- 229920001038 ethylene copolymer Polymers 0.000 description 2
- 238000001914 filtration Methods 0.000 description 2
- 230000004927 fusion Effects 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 229910052749 magnesium Inorganic materials 0.000 description 2
- 239000011777 magnesium Substances 0.000 description 2
- 239000000463 material Substances 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 2
- 239000003381 stabilizer Substances 0.000 description 2
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 2
- UQFJIMBGIHVYIX-UHFFFAOYSA-N 1,2$l^{2}-oxaluminane Chemical compound C1CC[Al]OC1 UQFJIMBGIHVYIX-UHFFFAOYSA-N 0.000 description 1
- CRSBERNSMYQZNG-UHFFFAOYSA-N 1-Dodecene Chemical compound CCCCCCCCCCC=C CRSBERNSMYQZNG-UHFFFAOYSA-N 0.000 description 1
- 229940106006 1-EICOSENE Drugs 0.000 description 1
- GQEZCXVZFLOKMC-UHFFFAOYSA-N 1-hexadecene Chemical compound CCCCCCCCCCCCCCC=C GQEZCXVZFLOKMC-UHFFFAOYSA-N 0.000 description 1
- HFDVRLIODXPAHB-UHFFFAOYSA-N 1-tetradecene Chemical compound CCCCCCCCCCCCC=C HFDVRLIODXPAHB-UHFFFAOYSA-N 0.000 description 1
- 238000001644 13C nuclear magnetic resonance spectroscopy Methods 0.000 description 1
- AFFLGGQVNFXPEV-UHFFFAOYSA-N Decene Chemical compound CCCCCCCCC=C AFFLGGQVNFXPEV-UHFFFAOYSA-N 0.000 description 1
- 229920002943 EPDM rubber Polymers 0.000 description 1
- 238000004566 IR spectroscopy Methods 0.000 description 1
- CCCMONHAUSKTEQ-UHFFFAOYSA-N Octadecene Chemical compound CCCCCCCCCCCCCCCCC=C CCCMONHAUSKTEQ-UHFFFAOYSA-N 0.000 description 1
- AQSJGOWTSHOLKH-UHFFFAOYSA-N Phosphite Chemical class [O-]P([O-])[O-] AQSJGOWTSHOLKH-UHFFFAOYSA-N 0.000 description 1
- 239000000654 additive Substances 0.000 description 1
- 150000001336 alkenes Chemical class 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminum Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 239000002216 antistatic agent Substances 0.000 description 1
- 238000007664 blowing Methods 0.000 description 1
- 238000009835 boiling Methods 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- 229910052799 carbon Inorganic materials 0.000 description 1
- 238000005266 casting Methods 0.000 description 1
- 239000003795 chemical substances by application Substances 0.000 description 1
- 125000000058 cyclopentadienyl group Chemical group C1(=CC=CC1)* 0.000 description 1
- 150000001993 dienes Chemical class 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000001125 extrusion Methods 0.000 description 1
- 230000002349 favourable Effects 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 239000010408 film Substances 0.000 description 1
- 239000003063 flame retardant Substances 0.000 description 1
- 239000007789 gas Substances 0.000 description 1
- 238000005227 gel permeation chromatography Methods 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 229910052736 halogen Inorganic materials 0.000 description 1
- 238000010438 heat treatment Methods 0.000 description 1
- VLKZOEOYAKHREP-UHFFFAOYSA-N hexane Chemical compound CCCCCC VLKZOEOYAKHREP-UHFFFAOYSA-N 0.000 description 1
- 229920001519 homopolymer Polymers 0.000 description 1
- VAMFXQBUQXONLZ-UHFFFAOYSA-N icos-1-ene Chemical compound CCCCCCCCCCCCCCCCCCC=C VAMFXQBUQXONLZ-UHFFFAOYSA-N 0.000 description 1
- 239000003999 initiator Substances 0.000 description 1
- 229910052747 lanthanoid Inorganic materials 0.000 description 1
- 150000002602 lanthanoids Chemical class 0.000 description 1
- 229920005684 linear copolymer Polymers 0.000 description 1
- 238000011068 load Methods 0.000 description 1
- 239000000314 lubricant Substances 0.000 description 1
- 229910001629 magnesium chloride Inorganic materials 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 229910052757 nitrogen Inorganic materials 0.000 description 1
- 239000002667 nucleating agent Substances 0.000 description 1
- 239000002530 phenolic antioxidant Substances 0.000 description 1
- 239000000049 pigment Substances 0.000 description 1
- 239000004014 plasticizer Substances 0.000 description 1
- 229920000306 polymethylpentene Polymers 0.000 description 1
- 229920000098 polyolefin Polymers 0.000 description 1
- 229920001155 polypropylene Polymers 0.000 description 1
- 238000010992 reflux Methods 0.000 description 1
- 239000002356 single layer Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000011949 solid catalyst Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 230000000707 stereoselective Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000000725 suspension Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 150000003609 titanium compounds Chemical class 0.000 description 1
Abstract
Polyethylene composition comprising (percentages by weight):A) from 60 to 95%of an LLDPE copolymer having a density from 0.905 to 0.935 g/cm3, Mw/Mn values less than 4 and F/E ratio values greater than 20;B) from 5 to 40%of one or more crystalline copolymers of propylene selected from among defined copolymers of propylene with ethylene and/or higher alpha-olefins.
Description
POLYETHYLENE COMPOSITIONS THAT HAVE IMPROVED OPTICAL AND MECHANICAL PROPERTIES AND CAPACITY OF
IMPROVED PROCESSING IN CASTING STATE
DESCRIPTIVE MEMORY
The present invention relates to polyethylene compositions containing a linear copolymer of low density of ethylene (LLDPE, for its acronym in English) having a narrow molecular weight distribution, and a crystalline copolymer of propylene. The films obtained from said compositions possess an excellent balance of mechanical and optical properties. In addition, the aforementioned compositions are easily processable in their molten state, since they do not require large energy costs in the machines used for their processing and do not cause high pressures in the heads of the machines. The ethylene copolymer used for the compositions of the present invention possesses a molecular weight distribution, in terms of the ratio between the weight average molecular weight (PMP) and the number average molecular weight (PMn), which is in terms of PMp / PMn, which is particularly narrow (corresponding to the values of PMp / PMn less than 4) and therefore, typical of the polyethylenes obtained with metallocene catalysts.
»^^. ^^^^^^^^^^^^^^^^^^^^ 11 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ In this regard, the compositions of the present invention differ from the compositions described in published patent applications WO 93/03078 and WO 95/20009, in which the LLDPE copolymer (which is mixed with a crystalline copolymer of propylene) is prepared with Ziegler-Natta catalysts and therefore has PMp / PMn values typically greater than or equal to 4. In accordance with the US patent 4,871, 813, it is possible to prepare copolymers of LLDPE having PMp / PMn values of less than 4 (from 2.5 to 6) even when the catalyst used is of the Ziegler-Natta type, however in the examples only one LLDPE copolymer is used which it has a PMp / PMn value of 4. Also, in the US patent cited above, the LLDPE copolymer is mixed with a propylene copolymer; however, the crystallinity of this propylene polymer is somewhat low, as indicated by the low values of heat of fusion (less than or equal to 75 J / g) and, in particular, the degree of crystallinity (less than 35%) . The aforementioned documents show that by means of the addition of the propylene copolymer to the LLDPE copolymer, polyethylene compositions are obtained which have an improved processing capacity in their molten state, in the aforementioned sense. In accordance with the patent of E.U.A. 4,871, 813, this effect is achieved without substantially changing the optical and mechanical properties of
the film, compared with those of a film obtained from the pure LLDPE copolymer. In accordance with the published patent application WO 95/20009, the addition of the crystalline propylene copolymer is capable of improving the processing capacity in the molten state, as well as the resistance of the polyethylene film to impact and tearing. However, the optical properties of the compositions possessed by an LLDPE copolymer obtained with Ziegler-Natta catalysts and a propylene copolymer are lower, in particular as regards the values of turbidity and brightness, with respect to those typical of a LLDPE copolymer obtained with metallocene catalysts and having relatively high F / E ratio values, ie greater than 20. The aforementioned LLDPE copolymers obtained with metallocene catalysts generally show turbidity values
less than about 20% and brightness values greater than about 30% (measured in blown film of a thickness of 25 μm by the method described in the examples). Corresponding to said high values of turbidity and gloss, said LLDPE polymers also possess satisfactory values of impact resistance (Dart test) and tear resistance (Elmef).
However, the LLDPE copolymers obtained with metallocene catalysts show an unsatisfactory processing capacity in the molten state. This is why it is particularly convenient to obtain
polyolefin compositions having the aforementioned optical properties, with the best possible balance of impact resistance and tear strength and good processability in their molten state. In the patent of E.U.A. No. 5,674,945, there are disclosed polyethylene compositions 10 containing a copolymer of LLDPE obtained with metallocene catalysts and a propylene copolymer having a density greater than or equal to 0.900 g / m2. In particular, a copolymer containing 0.2 mol% of butene and a copolymer containing 3.4 mol% of ethylene and 1.6 mol% of butene is used in the examples. In both cases, the relative amount of propylene copolymer in the polyethylene compositions is 10% by weight, and the transparency of the films obtained from said compositions turns out to be substantially free of change compared to the transparency of the films obtained from
the corresponding LLDPE copolymers in their pure state. In addition, the films obtained from the aforementioned compositions show high values of tensile modulus of elasticity,
'? lÉíi_r •• - "-'" - '-' •. * .. »• > - -J- *** ** _? _ Dl_Hi_riíM _? ___ áÉ ?? __ ^ rii_M ___ MÉ_tt _ ^ __ M higher than those of the films obtained from the corresponding LLDPE copolymers in their pure state, and high breaking load values. The technical problem of obtaining an excellent balance of optical properties, resistance to impact and resistance to tearing is not considered. Now, polyethylene compositions have been created that completely satisfy the aforementioned requirements, thanks to an unusual and particularly favorable balance of mechanical and optical properties and processing capacity in the molten state. Accordingly, the object of the present invention is constituted by polyethylene compositions compng (percentages by weight): A) from 60 to 95%, preferably from 60 to 90%, most preferably from 70 to 88%, of a copolymer of ethylene with an alpha-olefin CH2 = CHR, in which R is an alkyl radical containing from 1 to 18 carbon atoms
carbon (LLDPE copolymer), said copolymer having a density of 0.905 to 0.935 g / cm3, preferably 0.910 to 0.930, most preferably 0.915 to 0.925 g / cm3 (measured in accordance with ASTM D 4883), PMp / PMn values less than 4, preferably from 1.5 to 3.5, most preferably from 1.5 to 3 (measured by GPC, ie gel permeation chromatography) and
F / E ratio values greater than 20, preferably from 25 to 70, most preferably from 25 to 50 (measured in accordance with ASTM D 1238); B) from 5 to 40%, preferably from 10 to 35%, most preferably from 12 to 30%, of one or more crystalline copolymers of
propylene selected from (i) copolymers of propylene with ethylene containing from 3 to 8%, preferably from 4 to 6%, of ethylene; (ii) copolymers of propylene with one or more alpha-olefins CH2 = CHR ', wherein R1 is an alkyl radical having from 2 to 8 carbon atoms or an aryl radical, containing from 5 to 25%, preferably from 8 to 20%, of alpha-olefins CH2 = CHR '; (Ii) copolymers of propylene with ethylene and one or more alpha-olefins CH2 = CHR ', wherein R1 has the aforementioned meaning, and contains from 0.1 to 8%, preferably from 0.5 to 5%, most preferably from 1 to 4%, ethylene, and from 0.1 to 20%, preferably from 1 to 15%, most preferably from 2.5 to 15%, in
Particularly from 2.5 to 10%, of alpha-olefins CH2 = CHR ', with the proviso that the total content of ethylene and alpha-olefins CH2 = CHR' in the copolymers (ii) is greater than or equal to 5%. %. Optionally, in order to improve the optical properties, the compositions of the present invention may contain, in addition to the
components A) and B), from 0.5 to 10%, preferably from 1 to 6%, by weight of a LDPE polyethylene (component C), in relation to the total weight of A) + B) + C). As seems obvious from the above description, polymers containing two or more types of comonomers are also
include in the definition of copolymers. The aforementioned compositions are generally characterized by turbidity values of less than or equal to 25%, preferably less than or equal to 20%, in particular between 20 and 5%, and
gloss values greater than about 30%, in particular between 30 to 60% (measured in blown film of a thickness of 25 μm by the method described in the examples). In addition, the compositions of the present invention are generally characterized by dart test values greater than or
Equal to 150 g, preferably greater than or equal to 200 g, in particular between 150 and 400 g, preferably between 200 and 400 g (measured in blown film of a thickness of 25 μm by the method described in the examples). In addition, the compositions of the present invention show particularly high tear strength values (Elmendorf), as such and in consideration with the dart test values. Generally, said values are greater than or equal to 400 g (measured in blown film of a thickness of 25 μm by the method described in the examples) in the transverse direction (DT), in particular between 400 and 800 g, and greater than or Equal to 150 g in the machine direction (DM); preferably greater than or equal to 200 g, in particular between 150 and 350 g, preferably between 200 and 350 g. Generally, component A) of the compositions of the present invention have an ethylene content greater than or equal to 60% by weight, in particular from 60 to 99%, preferably greater than or equal to 70% by weight, in particular from 70 to 99%, most preferably greater than or equal to 80% by weight, in particular from 80 to 99%.
Some examples of alpha-olefins CH2 = CHR present in component A) of the compositions of the present invention are propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl l-1-pentene, 1-ketene, 1 -decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene. Some preferred examples are 1-butane, 1-hexane and 1-octane. Generally, component A) possesses E values of molten material flow rate (MFR E in accordance with ASTM D 1238) from 0.1 to 100 g / 10 min. In addition, said component A) preferably has a fraction content soluble in xylene at 25 ° C less than or equal to 5% by weight. The trace of the DSC (Differential Scanning Calorimetry) of said component A) preferably shows a single melting peak (typical of a crystalline phase); this peak is generally located at a temperature greater than or equal to 100 ° C. LLDPE copolymers having the aforementioned characteristics for component A) are known in the art and can be obtained by conventional polymerization processes (in gas phase, in suspension or in solution) using catalysts comprising a compound of an element of transition, preferably Ti, Zr or Hf, or of the lanthanide series, wherein this element is combined with at least one cyclopentadienyl group, and a cocatalyst, in particular an alumoxane or a compound capable of forming an alkyl cation.
• riRTTÉIf1 ^ - - "- - - • ***» ^ * "'*' *» > ^ * > ~ * "* < '»> ~ * - ~ * ™ - -.- w «« * ^ * Some examples of the aforementioned catalysts and polymerization processes are described in published patent application WO 93/08221. Some examples of alpha-olefins CH2 = CHR 'present in component B) of the compositions of the present invention are 1-butane, 1-pentene, 4-methylpentene-1, 1-hexene and 1-ketene. 1 -butene is preferred. Generally, component B) has L values of melt flow rate (MFR L in accordance with ASTM D 1238) of 0.1 to 500 g / 10 min., preferably from 1 to 50, most preferably from 6 to 25 10 g / 10min. Preferably said component B) has density values (measured in accordance with ASTM D 4883) of less than 0.9 g / cm3, in particular of 0.890 to 0.899, most preferably 0.892 to 0.899. In addition, said component B) preferably has the following characteristics: content of fraction insoluble in xylene at 25 ° C greater than 70% by weight, very preferably greater than or equal to 75%, in particular greater than or equal to 85% in weight; heat of fusion (measured in accordance with ASTM D 3418-82) greater than 50 J / g, most preferably greater than or equal to 60 J / g, in particular greater than or equal to 70 J / g, for example from 75 to 95 J / g; melting point (measured in accordance with STM DD 3418-82) less than 140 ° C, most preferably 120 to 140 ° C;
__________ • -. - 3-*-- . .-. . ___..___ ftfflff-i ***** - > - «» > * «• -» »- • - • ---. ^. ^ M ^^ Mi.
PMp / PMn values greater than 3.5, in particular from 3.5 to 15. The crystalline propylene copolymers having the above-mentioned characteristics for component B) are known in the art, and can be obtained by conventional polymerization processes using Ziegler-Natta catalysts stereospecific supported by magnesium halides. Said catalysts contain, as an essential component, a solid catalyst component comprising a titanium compound having at least one titanium-halogen bond and an electron donor compound, both supported by a magnesium halide. As cocatalysts a alalkyl compound and an electron donor compound are generally used. Catalysts having the aforementioned characteristics are described, for example, in the patent of E.U.A. 4,399,054 and European Patent 45977. The LDPE (low density polyethylene) polymer constituting component C) of the compositions of the present invention is an ethylene homopolymer or an ethylene copolymer containing minor amounts of comonomers, such as acrylate butyl, prepared by high pressure polymerization using free radical initiators. The density of said LDPE polymer generally ranges from 0.910 to 0.925 g / cm 3 (measured in accordance with ASTM D 4883).
* * ¿?? **? I. . ^ •• -! •! , ^ T * A ^ __ te_f_____ ^ _ ^.-_ > ___ ¿_...---; . ... _ Mfl Afc_ «, The MFR E values of said LDPE polymer are generally in the range of 0.1 to 50 g / 10 min, preferably 0.3 to 20 g / 10 min. LDPE polymers having the above characteristics mentioned for component C) are known in the art. Some specific examples are commercially available polymers with the trade names of Escorene, and Lupolen (BASF). In addition to the aforementioned components, the compositions of the present invention may contain other polymeric components, such as olefin elastomers, or ethylene / propylene (EPR) or ethylene / propylene / diene (EPDM) elastomers, and additives commonly used in the process. technical, as stabilizers (in particular phenolic antioxidants and process stabilizers such as organic phosphites), pigments, fillers, nucleating agents, releasing agents, lubricating and antistatic agents, flame retardants and plasticizers. The compositions of the present invention can be prepared by means of polymerization processes in two or more consecutive steps, using at least one step the catalysts described above for the preparation of component A) and at least one different step in the catalysts. of Ziegler-Natta described above for the preparation of component B), and optionally adding component C) by mixing in the molten state.
Naturally, it is also possible to prepare the compositions of the present invention by mixing components A), B), and optionally C), in the molten state. The melt mixing processes conveniently used are of the conventional type and are based on the use of mixing devices known in the art, such as single and double-screw extruders. In view of its easy processing capacity in the molten state and its excellent optical and mechanical properties, the compositions of the present invention are particularly suitable for the preparation of molded articles in general, and in particular of film, single layer or multiple layers , either fused or mono or biaxially oriented, including blown films, in which at least one layer comprises the aforementioned compositions. The processes for the preparation of blown film are well known in the art and comprise an extrusion step through a head with an annular opening. The product of this stage is a tubular extrudate that is inflated with air, to obtain a tubular bubble that cools and collapses to obtain the film. The following examples are given for the purpose of illustrating but not limiting the present invention. The following materials are used for these examples:
^ teA .. > . *. - * «- * - tJB__i ___« u ^^^ 1 ^^ M? »*.
A) Copolymer of LLDPE ethylene / 1-ketene copolymer, marketed by DOW CHEMICAL COMPANY under the name "Affinity-1570", containing 10.8% by weight of 1-ketene (deteed by 13C NMR) and having the following 5 characteristics: Density (ASTM D 4883): 0.9130 g / cm3 PMpPMn (GPC): approx. 2.5 MFR E (ASTM D 1238): 1.0 g / 10 min F / E (ASTM D 1238): 41 10 Soluble in xylene at 25 ° C (% by weight): 3.2
B) Crystalline propylene copolymer A propylene copolymer having the following characteristics is used: Butene content (% by weight) 5.3 Ethylene content (% by weight): 2.2 Density (g / cm3): 0.895 MFR L (g / 10 min): 6 Soluble in xylene at 25 ° C (% by weight) 10
Note: the aforementioned contents of butene and ethylene are measured by IR spectroscopy, the density by ASTM D 4883, and the insoluble content in xylene (and hence the soluble content) is deteed by the following method:
__? i_i__g? _l_M ____ M_É kiiíii? á? l l_ft_p_rlimi? i - "* • - * • '" - .. - ^ «-___-_ * __ a_ 2.5 g of copolymer together with 250 cm3 of oxylene are placed in a conical glass flask, equipped with condenser and magnetic stirrer. The temperature rises to the boiling point of the solvent in 30 minutes. The clear solution thus formed is allowed to reflux with stirring for another 30 minutes. The closed flask is then placed in a water and ice bath for 30 minutes and then in a water bath under a thermostat at 25 ° C for 30 minutes. The solid formed is filtered on paper at a high filtration rate. 100 cm3 of the liquid obtained from the filtration are emptied into an aluminum container, previously weighed, and everything is placed in a
heating plate to evaporate the liquid in a stream of nitrogen. The container is then placed in an oven at 80 ° C and kept under vacuum until a constant weight is reached. The aforementioned propylene copolymers are prepared using high performance Ziegler-Natta catalysts and
stereospecificity, supported by magnesium chloride, in the polymerization.
EXAMPLE 1
The aforementioned components A) and B) are mixed in their molten state in a single-screw extruder (Flag TR-60) under the following conditions: Temperature profile: 185, 195, 200, 205, 210, 215, 235, melted at 230 ° C; Propeller revolutions: 70 rpm; Performance: 67 kg / hr
The relative amounts of the aforementioned components are equal to 80% by weight of A) and 20% by weight of B), relative to the total weight of the composition. From the composition obtained in this way, a blown film of 25 μm thickness is prepared using a COLLIN-25 machine under the following conditions:
Temperature profile: 155, 165, 175, 185, 190, 190, 190, 190, melted 200 ° C; Propeller revolutions: 90 rpm; Performance: 67 kg / hr Blowing rate 2.5.
The properties shown in table 1 are measured in the film thus prepared. For comparison purposes, Table 1 also shows the properties of a blown film obtained and tested under the same conditions as in Example 1, but using component A) in its pure state (reference example 1).
TABLE 1
With respect to table 1, the head pressure corresponds to the pressure measured in the extruder head while the motor input refers to the extruder motor. In addition, the properties of the films shown in Table 1 are measured by the following standard ASTM methods:
Turbidity: ASTM D 1003 Brightness: ASTM D 2457 Dart test: ASTM D 1709 10 Elmendorf: ASTM D 1922.
Claims (7)
1. - A polyethylene composition comprising (percentages by weight): A) from 60 to 95% of a copolymer of ethylene with an alpha-olefin CH2 = CHR, wherein R is an alkyl radical containing from 1 to 18 carbon atoms , said copolymer having a density of 0.905 to 0.935 g / cm3, PMp / PMn values less than 4, and F / E ratio values greater than 20; B) from 5 to 40% of one or more crystalline propylene copolymers selected from (i) copolymers of propylene with ethylene containing from 3 to 8% ethylene; (ii) copolymers of propylene with one or more alpha-olefins CH2 = CHR ', wherein R1 is an alkyl radical having from 2 to 8 carbon atoms or an aryl radical, containing from 6 to 25% alpha-olefin CH2 = CHR '; (iii) copolymers of propylene with ethylene and one or more alpha-olefin CH2 = CHR ', wherein R1 has the aforementioned meaning, containing 0.1 to 8% ethylene and 0.1 to 20% alpha-olefin CH2 = CHR ', with the proviso that the total content of ethylene and alpha-olefin CH2 = CHR' in the copolymers (ii) is greater than or equal to 5%.
2. The polyethylene composition according to claim 1, further characterized in that it contains: C) from 0.5 to 10% by weight, based on the total weight of A) + B) + C), of LDPE polyethylene.
3. - The polyethylene composition according to claim 1, further characterized in that the component B) has a density less than 0.900 g / cm3.
4. The polyethylene composition according to claim 1, further characterized in that the component B) has a fraction insoluble in xylene at 25 ° C greater than 70% by weight.
5. The polyethylene composition according to claim 1, further characterized in that it has turbidity values, measured in blown film of a thickness of 25 μm in accordance with ASTM D 1003, less than or equal to 25%.
6. A film of a layer or multiple layers, characterized in that at least one layer comprises the polyethylene composition according to claim 1.
7. A blown film according to claim 6.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
MIMI98A001548 | 1998-07-07 |
Publications (1)
Publication Number | Publication Date |
---|---|
MXPA01000148A true MXPA01000148A (en) | 2001-09-07 |
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