WO2012066119A2 - Utilisation de métallocène-polypropylène dans le thermoformage - Google Patents

Utilisation de métallocène-polypropylène dans le thermoformage Download PDF

Info

Publication number
WO2012066119A2
WO2012066119A2 PCT/EP2011/070446 EP2011070446W WO2012066119A2 WO 2012066119 A2 WO2012066119 A2 WO 2012066119A2 EP 2011070446 W EP2011070446 W EP 2011070446W WO 2012066119 A2 WO2012066119 A2 WO 2012066119A2
Authority
WO
WIPO (PCT)
Prior art keywords
polypropylene
sheet
composition
metallocene
article
Prior art date
Application number
PCT/EP2011/070446
Other languages
English (en)
Other versions
WO2012066119A3 (fr
Inventor
Fabienne Radermacher
Cristo Boukalidis
Original Assignee
Total Petrochemicals Research Feluy
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Total Petrochemicals Research Feluy filed Critical Total Petrochemicals Research Feluy
Publication of WO2012066119A2 publication Critical patent/WO2012066119A2/fr
Publication of WO2012066119A3 publication Critical patent/WO2012066119A3/fr

Links

Classifications

    • 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

Definitions

  • the present invention relates to sheets and thermoformed articles comprising a polypropylene layer, which consists of a polypropylene composition comprising a polypropylene produced with a metallocene-based polymerization catalyst.
  • the present invention further relates to a process for producing such sheets and thermoformed articles.
  • thermoforming a soft polymer sheet is draped over or into a form or mold.
  • a thermoforming process comprises for example the steps of
  • thermoforming is a low-pressure and low-temperature process.
  • the polymer sheet serving as feedstock for the thermoforming process may for example be produced by melt-extrusion.
  • melt-extrusion one often refers to "extrusion- thermoforming" to denote the complete process with the two distinct processing stages of
  • thermoforming stage wherein the polymer is formed or shaped.
  • Extrusion-thermoforming comes in numerous variations. It may for example be done either in-line, i.e. the sheet coming from the sheet-extrusion stage is directly fed to the thermoforming stage, or off-line, i.e. the sheet is stored for some time before being fed to the thermoforming stage.
  • extrusion-thermoforming polypropylene is of great interest because it combines low cost and good productivity with good mechanical and chemical properties.
  • the difficulty lies in finding the balance between the polymer properties required to have good processability both, in the extrusion stage as well as in the thermoforming stage. These requirements may in some cases even exclude each other.
  • high melt strength may improve the performance in the thermoforming stage, at the same time this might for example require higher extruder pressures or higher die pressures or higher melt temperatures in the extrusion stage to produce a sheet of a quality suited for the subsequent thermoforming stage.
  • thermoforming and extrusion-thermoforming are for example given in J.L. Throne, Understanding Thermoforming, Carl Hanser Verlag, Kunststoff, 1999 and in J.L. Throne, Thermoforming, Carl Hanser Verlag, Kunststoff, 1987.
  • melt flow index as measured according to ISO 1 133, condition L, at 230°C and 2.16 kg
  • melt flow index as measured according to ISO 1 133, condition L, at 230°C and 2.16 kg
  • thermoforming stage It is a further objective to provide a process for the production of a thermoformed article, wherein the processability in the extrusion stage is improved, while the processability in the thermoforming stage remains comparable.
  • thermoforming stage Furthermore, it is an objective to provide sheet that can be well processed in the thermoforming stage.
  • any of these objectives can be met by providing sheet or thermoformed articles comprising a polypropylene layer consisting of a polypropylene composition comprising a polypropylene produced with a metallocene-based polymerization catalyst, wherein the polypropylene has specific properties.
  • an article comprising a polypropylene layer, said polypropylene layer consisting of a polypropylene composition comprising at least 50 wt%, relative to the total weight of said polypropylene layer, of a polypropylene produced with a metallocene-based polymerization catalyst, wherein the article is a sheet or a thermoformed article, and the polypropylene has a melt flow index of at least 10 dg/min and of at most 25 dg/min, as determined according to ISO 1 133, condition L, at 230°C and 2.16 kg.
  • step (c) melt-extruding the molten polypropylene composition obtained in step (b) through a slit die to form an extrudate;
  • polypropylene has a melt flow index of at least 10 dg/min and of at most 25 dg/min, as determined according to ISO 1 133, condition L, at 230°C and 2.16 kg.
  • a polypropylene composition comprising at least 50 wt%, relative to the total weight of said article, of a polypropylene produced with a metallocene-based polymerization catalyst in the production of a sheet or a thermoformed article, wherein the polypropylene has a melt flow index of at least 10 dg/min and of at most 25 dg/min, as determined according to ISO 1 133, condition L, at 230°C and 2.16 kg.
  • melt flow index abbreviated as "MFI”
  • MI2 melt index
  • sheet is defined as having a thickness in the range from 500 pm to 2000 pm, and preferably from 700 pm to 1500 ⁇
  • tetrahydroindenyl signifies an indenyl group wherein the six-membered ring has been hydrogenated to form 4,5,6,7-tetrahydroindenyl.
  • the article provided for herein is a sheet or a thermoformed article and comprises a polypropylene layer consisting of a polypropylene composition comprising at least 50 wt%, relative to the total weight of said polypropylene composition, of a polypropylene produced with a metallocene-based polymerization catalyst.
  • said polypropylene composition comprises at least 60 wt%, more preferably at least 70 wt% or 80 wt%, even more preferably at least 90 wt% or 95 wt%, and still even more preferably at least 97 wt% or 99 wt%, relative to the total weight of said polypropylene composition, of a polypropylene produced with a metallocene-based polymerization catalyst.
  • said polypropylene composition consists of a polypropylene produced with a metallocene-based polymerization catalyst.
  • the article provided for herein further comprises a polyethylene layer, which consists of a polyethylene composition comprising at least 50 wt%, relative to the total weight of said polyethylene composition, of a polyethylene produced with a metallocene-based polymerization catalyst, wherein the polypropylene layer and the polyethylene layer are directly adjacent to one another, i.e. without a tie layer in between.
  • a polyethylene layer which consists of a polyethylene composition comprising at least 50 wt%, relative to the total weight of said polyethylene composition, of a polyethylene produced with a metallocene-based polymerization catalyst, wherein the polypropylene layer and the polyethylene layer are directly adjacent to one another, i.e. without a tie layer in between.
  • the polypropylene composition used herein may further comprise a thermoplastic polymer different from the polypropylene produced with a metallocene-based polymerization catalyst as defined in the present application.
  • the polyethylene composition used herein may further comprise a thermoplastic polymer different from the polyethylene produced with a metallocene-based polymerization catalyst as defined in the present application.
  • Preferred suitable thermoplastic polymers are for example propylene homopolymers, copolymers of propylene and at least one comonomer, ethylene homopolymers, copolymers of ethylene and at least one comonomer, wherein said at least one comonomer is defined as stated below.
  • Suited propylene homopolymers or copolymers may be produced with a Ziegler-Natta polymerization catalyst.
  • Suitable ethylene homopolymers or copolymers may be characterized by different densities and may be produced with various polymerization catalysts, such as chromium-based polymerization catalysts, metallocene-based polymerization catalysts or Ziegler-Natta catalysts, or by a radical polymerization process.
  • polymerization catalysts such as chromium-based polymerization catalysts, metallocene-based polymerization catalysts or Ziegler-Natta catalysts, or by a radical polymerization process.
  • the melt flow index of the polypropylene composition resp. the melt index of the polyethylene composition used herein it is preferred that they are within the same ranges and values as defined below for the polypropylene resp. the polyethylene.
  • the polypropylene used herein has a melt flow index of at least 10 dg/min, preferably of at least 1 1 dg/min and most preferably of at least 12 dg/min.
  • the polypropylene used herein has a melt flow index of at most 25 dg/min, preferably of at most 20 dg/min, more preferably of at most 19 dg/min and most preferably of at most 18 dg/min.
  • the polypropylene used herein has a molecular weight distribution (MWD), defined as M w /M n , i.e. the ratio of weight average molecular weight M w over number average molecular weight M n , of at least 1 .0, more preferably of at least 1 .5 and most preferably of at least 2.0.
  • M w /M n molecular weight distribution
  • the polypropylene used herein has a molecular weight distribution, defined as M w /M n , of at most 4.0, more preferably of at most 3.5, even more preferably of at most 3.0, and most preferably of at most 2.8.
  • Molecular weights can be determined by size exclusion chromatography (SEC) as described in the test methods.
  • the polypropylenes having a melt flow index of at least 10 dg/min, preferably in combination with a narrower molecular weight distribution, as defined in the present application process well, both in the extrusion stage and in the thermoforming stage.
  • the sheet and thermoformed articles produced with such a polypropylene have comparable mechanical properties as compared to sheet and thermoformed articles produced with a "conventional" polypropylene recommended for thermoforming.
  • the polypropylene used herein is characterized by a high isotacticity, for which the content of mmmm pentads is a measure.
  • the content of mmmm pentads is at least 90 %, more preferably at least 95 %, and most preferably at least 97 %.
  • the isotacticity may be determined by 13 C-NMR analysis as described in the test methods.
  • the polypropylene used herein preferably is a propylene homopolymer or a random copolymer of propylene and up 6.0 wt%, relative to the total weight of said random copolymer, of at least one comonomer, said at least one comonomer being different from propylene, though propylene homopolymer is preferred.
  • the preferred random copolymer is a random copolymer of propylene and up to 5.0 wt%, more preferably up to 4.5 wt%, and most preferably up to 4.0 wt% of at least one comonomer, relative to the total weight of said random copolymer.
  • Preferred comonomers are a-olefins having from one to 10 carbon atoms.
  • Preferred a-olefins are ethylene, butene-1 , pentene-1 , hexene-1 , octene-1 and 3-methyl-pentene-1 .
  • More preferred ⁇ -olefins are ethylene and butene-1 .
  • the most preferred a-olefin is ethylene.
  • the polypropylene used herein is characterized by a melting temperature T me it of at most 160°C.
  • T me melting temperature
  • the present inventors believe that the lower melting temperature of the polypropylenes used herein seems to permit easier processability in the extrusion stage and also allows reducing the cycle time in the thermoforming stage.
  • the polypropylene used herein is characterized by lower melting temperatures so that less energy is required in the thermoforming stage to heat the sheet to a temperature at which it can be thermoformed.
  • less time is required for heating (assuming that the heaters are run at the same temperatures)
  • less time is required for cooling the formed sheet because less energy has to be removed.
  • the polypropylene used herein is characterized by a percentage of 2, 1 -insertions, relative to the total number of propylene molecules in the polymer chain, of at least 0.1 %.
  • the percentage of 2, 1 -insertions is at most 1 .5 %, more preferably at most 1 .3 %, even more preferably at most 1 .2 %, still even more preferably at most 1 .1 %, and most preferably at most 1 .0 %.
  • the method for determining the percentage of 2, 1 -insertions is given in the test methods.
  • the polypropylene used herein comprises a nucleating agent, more specifically an a-nucleating agent.
  • nucleating agent is defined as a chemical compound that raises the crystallization temperature of the polypropylene.
  • Suitable nucleating agents for use in the present invention can be selected from any of the nucleating agents known to the skilled person. It is, however, preferred that the nucleating agent be selected from the group consisting of talc, carboxylate salts, sorbitol acetals, phosphate ester salts, substituted benzene tricarboxamides and polymeric nucleating agents, as well as blends of these.
  • Examples for carboxylate salts are organocarboxylic acid salts. Particular examples are sodium benzoate and lithium benzoate.
  • the organocarboxylic acid salts may also be alicyclic organocarboxylic acid salts, preferably bicyclic organodicarboxylic acid salts and more preferably a bicyclo[2.2.1 ]heptane dicarboxylic acid salt.
  • a nucleating agent of this type is sold as HYPERFORM® HPN-68 by Milliken Chemical.
  • Examples for sorbitol acetals are dibenzylidene sorbitol (DBS), bis(p-methyl- dibenzylidene sorbitol) (MDBS), bis(p-ethyl-dibenzylidene sorbitol), bis(3,4- dimethyl-dibenzylidene sorbitol) (DMDBS), and bis(4-propylbenzylidene) propyl sorbitol.
  • DBS dibenzylidene sorbitol
  • MDBS bis(p-methyl- dibenzylidene sorbitol)
  • DDBS bis(p-ethyl-dibenzylidene sorbitol)
  • DDBS bis(3,4- dimethyl-dibenzylidene sorbitol)
  • DDBS bis(4-propylbenzylidene) propyl sorbitol
  • phosphate ester salts are salts of 2,2'-methylene-bis-(4,6-di-tert- butylphenyl)phosphate. Such phosphate ester salts are for example available as NA-1 1 or NA-21 from Asahi Denka.
  • substituted tricarboxamides are those of general formula (I)
  • R1 , R2 and R3, independently of one another, are selected from C1-C20 alkyls, C5-C12 cycloalkyls, or phenyl, each of which may in turn by substituted with C1-C20 alkyls, C5-C12 cycloalkyls, phenyl, hydroxyl, C1-C20 alkylamino or C-i- C20 alkyloxy etc.
  • C1-C20 alkyls are methyl, ethyl, n-propyl, n-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl, 1 , 1 -dimethylpropyl, 1 ,2-dimethylpropyl, 3-methylbutyl, hexyl, heptyl, octyl or 1 , 1 ,3,3-tetramethylbutyl.
  • C5- C12 cycloalkyl examples are cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, adamantyl, 2-methylcyclohexyl, 3-methylcyclohexyl or 2,3-dimethylcyclohexyl.
  • Such nucleating agents are disclosed in WO 03/102069 and by Blomenhofer et al. in Macromolecules 2005, 38, 3688-3695.
  • polymeric nucleating agents examples include polymeric nucleating agents containing vinyl compounds, which are for example disclosed in EP-A1 - 0152701 and EP-A2-0368577.
  • the polymeric nucleating agents containing vinyl compounds can either be physically or chemically blended with the metallocene random copolymer of propylene and one or more comonomers. In physical blending the polymeric nucleating agent containing vinyl compounds is mixed with the metallocene random copolymer of propylene and one or more comonomers in an extruder or in a blender.
  • the metallocene random copolymer of propylene and one or more comonomers comprising the polymeric nucleating agent containing vinyl compounds is produced in a polymerization process having at least two stages, in one of which the polymeric nucleating agent containing vinyl compounds is produced.
  • Preferred vinyl compounds are vinyl cycloalkanes or vinyl cycloalkenes having at least 6 carbon atoms, such as for example vinyl cyclopentane, vinyl-3-methyl cyclopentane, vinyl cyclohexane, vinyl-2-methyl cyclohexane, vinyl-3-methyl cyclohexane, vinyl norbornane, vinyl cylcopentene, vinyl cyclohexene, vinyl-2- methyl cyclohexene.
  • the most preferred vinyl compounds are vinyl cyclopentane, vinyl cyclohexane, vinyl cyclopentene and vinyl cyclohexene.
  • polymeric nucleating agents are poly-3-methyl-1 -butene, polydimethylstyrene, polysilanes and polyalkylxylenes. As explained for the polymeric nucleating agents containing vinyl compounds, these polymeric nucleating agents can be introduced into the metallocene polypropylene either by chemical or by physical blending.
  • high-density polyethylene such as for example Rigidex HD6070EA, available from INEOS Polyolefins, or a polypropylene having a fractional melt flow, or a polypropylene that comprises a fraction of fractional melt flow.
  • nucleating agents such as for example a blend of talc and a phosphate ester salt or a blend of talc and a polymeric nucleating agent containing vinyl compounds.
  • the nucleating agent may be introduced into the metallocene polypropylene by blending it with a nucleating agent, which is either in pure form or in form of a masterbatch, for example by dry-blending or by melt-blending. It is within the scope of the present invention that the nucleating agent can be introduced into the metallocene polypropylene by blending it with a nucleated thermoplastic polymer, wherein said thermoplastic polymer is different from the metallocene polypropylene
  • the nucleating agent or the blend of nucleating agents - if comprised at all - is present in the metallocene polypropylene in an amount of at least 50 ppm, preferably at least 100 ppm. It is present in an amount of at most 5000 ppm, preferably of at most 4000 ppm, even more preferably of at most 3000 ppm and most preferably of at most 2000 ppm.
  • the polypropylene used herein may also comprise further additives, such as by way of example, antioxidants, light stabilizers, acid scavengers, lubricants, antistatic additives, and colorants.
  • antioxidants such as by way of example, antioxidants, light stabilizers, acid scavengers, lubricants, antistatic additives, and colorants.
  • the polypropylene used herein is a metallocene polypropylene, i.e. it is produced with a metallocene-based polymerization catalyst, with the metallocene-based polymerization catalyst comprising a bridged metallocene component, a support and an activating agent.
  • a metallocene-based polymerization catalyst comprising a bridged metallocene component, a support and an activating agent.
  • Such metallocene-based polymerization catalysts are generally known in the art and need not be explained in detail.
  • the metallocene component can be described by the following general formula
  • R a is the bridge between R b and R c , i.e. R a is chemically connected to R b and R c , and is selected from the group consisting of -(CR 1 R 2 ) P - -(SiR 1 R 2 ) p - - (GeR 1 R 2 ) p - -(NR 1 )p- -(PR 1 ) P - -(N + R 1 R 2 ) P - and -(P + R 1 R 2 ) P - and p is 1 or 2, and wherein R 1 and R 2 are each independently selected from the group consisting of hydrogen, d-do alkyl, Cs-Cs cycloalkyi, C6-C15 aryl, alkylaryl with C1-C10 alkyl and C6-C15 aryl, or any two neighboring R (i.e.
  • R a is -(CR 1 R 2 ) P - or -(SiR 1 R 2 ) p - with R 1 , R 2 and p as defined above.
  • R a is -(SiR 1 R 2 ) p - with R 1 , R 2 and p as defined above.
  • Specific examples of R a include Me 2 C, ethanediyi (-CH 2 -CH 2 -), Ph 2 C and Me 2 Si.
  • M is a metal selected from Ti, Zr and Hf, preferably it is Is.
  • X 1 and X 2 are independently selected from the group consisting of halogen, hydrogen, C1-C10 alkyl, C6-C15 aryl, alkylaryl with C1-C10 alkyl and C6-C15 aryl.
  • X 1 and X 2 are halogen or methyl.
  • R b and R c are selected independently from one another and comprise a cyclopentadienyl ring.
  • Preferred examples of halogen are CI, Br, and I.
  • Preferred examples of C1-C10 alkyl are methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, and tert-butyl.
  • Preferred examples of C5-C7 cycloalkyi are cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.
  • Preferred examples of C6-C15 aryl are phenyl and indenyl.
  • alkylaryl with C1-C10 alkyl and C6-C15 aryl are benzyl (- CH 2 -Ph), and -(CH 2 ) 2 -Ph.
  • R b and R c may both be substituted cyclopentadienyl, or may be independently from one another unsubstituted or substituted indenyl or tetrahydroindenyl, or R b may be a substituted cyclopentadienyl and R c a substituted or unsubstituted fluorenyl.
  • R b and R c may both be the same and may be selected from the group consisting of substituted cyclopentadienyl, unsubstituted indenyl, substituted indenyl, unsubstituted tetrahydroindenyl and substituted tetrahydroindenyl.
  • unsubstituted is meant that all positions on R b resp. R c , except for the one to which the bridge is attached, are occupied by hydrogen.
  • substituted is meant that, in addition to the position at which the bridge is attached, at least one other position on R b resp.
  • R c is occupied by a substituent other than hydrogen, wherein each of the substituents may independently be selected from the group consisting of d-do alkyl, C5-C7 cycloalkyl, C6-C15 aryl, and alkylaryl with C1-C10 alkyl and C6-C15 aryl, or any two neighboring substituents may form a cyclic saturated or non- saturated C4-C10 ring.
  • a substituted cyclopentadienyl may for example be represented by the general formula CsR 3 R R 5 R 6 .
  • a substituted indenyl may for example be represented by the general formula C 9 R 7 R 8 R 9 R 10 R 1 1 R 12 R 1 3 R 14
  • a substituted tetrahydroindenyl may for example be represented by the general formula C9H 4 R 1 5 R 16 R 17 R 18 .
  • a substituted fluorenyl may for example be represented by the general formula Ci 3 R 19 R 20 R 21 R 22 R 23 R 2 R 25 R 26
  • Each of the substituents R 3 to R 26 may independently be selected from the group consisting of hydrogen, C1-C10 alkyl, C5-C7 cycloalkyl, C6-C15 aryl, and alkylaryl with C1-C10 alkyl and C6-C15 aryl, or any two neighboring R may form a cyclic saturated or non-saturated C 4 -Cio ring; provided, however, that not all substituents simultaneously are hydrogen.
  • Preferred metallocene components are those having C2-symmetry or those having C-i-symmetry. Most preferred are those having C2-symmetry.
  • Particularly suitable metallocene components are those wherein R b and R c are the same and are substituted cyclopentadienyl, preferably wherein the cyclopentadienyl is substituted in the 2-position, the 3-position, or simultaneously the 2-position and the 3-position.
  • Particularly suitable metallocene components are also those wherein R b and R c are the same and are selected from the group consisting of unsubstituted indenyl, unsubstituted tetrahydroindenyl, substituted indenyl and substituted tetrahydroindenyl.
  • Substituted indenyl is preferably substituted in the 2-position, the 3-position, the 4-position, the 5-position or any combination of these, more preferably in the 2-position, the 4-position or simultaneously in the 2-position and the 4-position.
  • Substituted tetrahydroindenyl is preferably substituted in the
  • Particularly suitable metallocene components may also be those wherein R b is a substituted cyclopentadienyl and R c is a substituted or unsubstituted fluorenyl.
  • the substituted cyclopentadienyl is preferably substituted in the 2-position, the
  • Said bulky substituent may for example be -CR 27 R 28 R 29 or -SiR 27 R 28 R 29 with R 27 , R 28 and R 29 independently selected from group consisting of d-do alkyl, C5-C7 cycloalkyl, C6-C-15 aryl, and alkylaryl with C1-C10 alkyl and C6-C15 aryl, or any two neighboring R may form a cyclic saturated or non-saturated C4-C10 ring, it is preferred that R 27 , R 28 and R 29 are methyl. Examples of particularly suitable metallocenes are:
  • the metallocene may be supported according to any method known in the art.
  • the support used in the present invention can be any organic or inorganic solid, particularly porous supports such as talc, inorganic oxides, and resinous support material such as polyolefin.
  • the support material is an inorganic oxide in its finely divided form.
  • the polymerization of propylene and the one or more optional comonomers in presence of a metallocene-based catalytic system can be carried out according to known techniques in one or more polymerization reactors.
  • the metallocene polypropylene used in the present invention is preferably produced by polymerization in liquid propylene at temperatures in the range from 20°C to 100°C. Preferably, temperatures are in the range from 60°C to 80°C.
  • the pressure can be atmospheric or higher. It is preferably between 25 and 50 bar.
  • the molecular weight of the polymer chains, and in consequence the melt flow of the metallocene polypropylene, is regulated by the addition of hydrogen to the polymerization medium.
  • the metallocene polypropylene is recovered from the one or more polymerization reactors without post-polymerization treatment to reduce its molecular weight and/or narrow its molecular weight distribution, such as can be done by thermal or chemical degradation, and is often done for polypropylene produced with a Ziegler-Natta catalyst.
  • the metallocene-catalyzed polyethylene preferably is a homopolymer of ethylene or copolymer of ethylene and at least one comonomer, said comonomer being a C3 to C10 a-olefin, such as 1 -butene, 1 -pentene, 1 -hexene, 1 -octene, 1 -methylpentene, with 1 -butene and 1 -hexene being the preferred comonomers and 1 -hexene being the most preferred comonomer.
  • the polyethylene used herein is a metallocene polyethylene, i.e. it is a polyethylene produced with a metallocene-based polymerization catalyst, with the metallocene-based polymerization catalyst comprising a metallocene component, a support and an activating agent.
  • metallocene-based polymerization catalysts are generally known in the art and need not be explained in detail..
  • R a is chemically connected to R b and R c , and is selected from the group consisting of -(CR 1 R 2 )p- -(SiR 1 R 2 )p- -(GeR 1 R 2 )p- -(NR 1 ) P - -(PR 1 ) P - -(N + R 1 R 2 ) P - and - (P + R 1 R 2 )p- and p is 1 or 2, and wherein R 1 and R 2 are each independently selected from the group consisting of hydrogen, d-do alkyl, Cs-Cs cycloalkyl, C6-C-15 aryl, alkylaryl with C1-C10 alkyl and C6-C15 aryl, or any two neighboring R may form a cyclic saturated or non-saturated C4-C10 ring; each R 1 and R 2 may in turn be substituted in the same way.
  • R a is -(CR 1 R 2 ) P - or - (SiR 1 R 2 ) p - with R 1 , R 2 and p as defined above. Most preferably R a is - (CR 1 R 2 ) P - with R 1 , R 2 and p as defined above. Specific examples of R a include Me 2 C, ethanediyl (-CH 2 -CH 2 -), Ph 2 C and Me 2 Si.
  • M is a metal selected from Ti, Zr and Hf, preferably it is Zr.
  • X 1 and X 2 are independently selected from the group consisting of halogen, hydrogen, C1-C10 alkyl, C6-C15 aryl, alkylaryl with C1-C10 alkyl and C6-C15 aryl.
  • X 1 and X 2 are halogen or methyl.
  • R b and R c are selected independently from one another and comprise a cyclopentadienyl ring, which may be substituted or unsubstituted.
  • unsubstituted is meant that all positions on the cyclopentadienyl ring, except for the one to which - if present - the bridge is attached, are occupied by hydrogen.
  • substituted is meant that, in addition to the position at which - if present - the bridge is attached, at least one position on the cyclopentadienyl ring is occupied by a substituent other than hydrogen, wherein each of the substituents may independently be selected from the group consisting of C1-C10 alkyl, C5-C7 cycloalkyl, C6-C15 aryl, and alkylaryl with C1-C10 alkyl and C6-C15 aryl, or any two neighboring substituents may form a cyclic saturated or non- saturated C4-C10 ring.
  • halogen are CI, Br, and I.
  • Preferred examples of C1-C10 alkyl are methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, and tert-butyl.
  • Preferred examples of C5-C7 cycloalkyl are cyclopentyl, cyclohexyl, cycloheptyl and cyclooctyl.
  • C6-C15 aryl are phenyl and indenyl.
  • alkylaryl with C1-C10 alkyl and C6-C15 aryl are benzyl (- CH 2 -Ph), and -(CH 2 ) 2 -Ph. It is, however, preferred to use a metallocene component of the following general formula, wherein
  • R a is -(CR 1 R 2 )p- or -(SiR 1 R 2 ) p - most preferably R a is -(CR 1 R 2 ) P - with R 1 , R 2 and p as defined above;
  • - M is a metal selected from Ti, Zr and Hf, preferably it is Zr;
  • - X 1 and X 2 are the same and are halogen or methyl, preferably chlorine or methyl, and most preferably chlorine;
  • R b and R c are selected independently from one another and comprise an indenyl or tetrahydroindenyl.
  • the indenyl or tetrahydroindenyl if substituted, is symmetrically substituted in position 2 or position 4 or both, and more preferably they are unsubstituted.
  • metallocene components include the following: bis(n-butylcyclopentadienyl)zirconium dichloride,
  • the polyethylene used herein has a molecular weight distribution (MWD), defined as M w /M n , i.e. the ratio of weight average molecular weight M w over number average molecular weight M n , of at least 1 .0, more preferably of at least 1 .5 and most preferably of at least 2.0.
  • M w /M n molecular weight distribution
  • the polyethylene used herein has a molecular weight distribution, defined as M w /M n , of at most 5.0, more preferably or at most 4.0, and most preferably of at most 3.5.
  • Molecular weights can be determined by size exclusion chromatography (SEC) as described in the test methods.
  • the metallocene-catalyzed polyethylene used in the present invention has a melt flow index in the range from 1 .0 dg/min to 10 dg/min.
  • the metallocene-catalyzed polyethylene used herein has a density of at least 0.920 g/cm 3 , more preferably of at least 0.925 g/cm 3 or 0.930 g/cm 3 , even more preferably of at least 0.935 g/cm 3 or 0.940 g/cm 3 , still even more preferably of at least 0.945 g/cm 3 and most preferably of at least 0.950 g/cm 3 .
  • it has a density of at most 0.970 g/cm 3 , more preferably of at most 0.965 g/cm 3 , and most preferably of at most 0.960 g/cm 3 .
  • the metallocene-catalyzed polyethylene used herein can be produced by methods generally known to the skilled person.
  • the polymerization of ethylene and - if present - one or more comonomers can for example be carried out in the gas phase. It may also be carried out in a liquid polymerization medium, such as for example a hydrocarbon that is inert under polymerization conditions, such as for example alkanes such as isobutane or isopentane or butane or pentane or propane, preferably in a loop reactor.
  • the polypropylene used herein is particularly suited for the production of thermoformed articles.
  • articles are food storage containers, drinking cups etc.
  • Thermoformed articles are generally produced by a two-stage process, wherein in the first stage a sheet is produced by melt-extruding a polymer (melt- extrusion stage), and in the second stage said sheet is shaped (thermoforming stage).
  • the two stages may either directly follow each other (in-line thermoforming) or they may not directly follow each other, in which case the produced sheet is stored for some time (e.g. a few hours, days or months) first and only later fed to the thermoforming stage.
  • the sheet may be produced on any melt extrusion sheet line, the production process for example comprising the steps of
  • step (c) melt-extruding the molten polypropylene composition obtained in step (b) through a slit die to form an extrudate
  • the sheet may further comprise a polyethylene layer as defined above in the present application.
  • the sheet may be produced by co- extrusion.
  • the respective production process may for example comprise the steps of
  • step (c) melt-extruding the molten polypropylene composition obtained in steps (b) and the molten polyethylene composition obtained in step (b 1 ) through a slit die to form an extrudate comprising a polypropylene composition layer and a polyethylene composition layer;
  • the molten polypropylene composition or, when applicable, the molten polyethylene composition or, when applicable, both may be passed through a melt pump and then be melt extruded.
  • Melt temperatures for the polypropylene composition and, when applicable, the polyethylene composition in the sheet extrusion stage generally are in the range from 200°C to 280°C, preferably in the range from 210°C to 270°.
  • process for producing sheet is well known (see for example the already cited J.L. Throne, Understanding Thermoforming, Carl Hanser Verlag, Kunststoff, 1999 and in J.L. Throne, Thermoforming, Carl Hanser Verlag, Kunststoff, 1987) to the skilled person no further description is deemed necessary. Exemplary sheet production conditions are given in the examples.
  • the polypropylene composition provided to the extruder in step (a) is as defined earlier in this application.
  • the polyethylene composition provided to the extruder in step (a 1 ) is as defined earlier in this application.
  • thermoforming stage can be done on any thermoforming machine comprising a heating and a forming section, said thermoforming process comprising the steps of
  • the process may further comprise a step of warming the sheet to a temperature at which it is soft before it is draped.
  • a step of warming the sheet may particularly be required when sheet production and thermoforming are done "off-line", i.e. not in series, and/or the sheet is stored for some time to allow it to cool to a temperature below the temperature at which it can be draped.
  • the thermoforming stage may comprise a further step
  • step (e) warming the sheet obtained in step (d) to a temperature at which it is soft, to obtain a soft sheet
  • the propylene polymer of the present invention can be processed under conditions that are comparable to the conditions used for a polypropylene conventionally used in thermoforming, i.e. a polypropylene being characterized by lower melt flow index.
  • the process may comprise a trimming step.
  • Trimming is usually defined as the process of mechanical breaking the formed sheet into two pieces, one of which is the desired thermoformed article, the other being the edge trim.
  • the process as defined optionally comprises the step of
  • step (i) trimming the formed sheet obtained in step (h) to obtain a thermoformed article.
  • the present application also discloses the use of a polypropylene composition as defined earlier in this application in the production of a sheet or thermoformed article.
  • Melt flow index (MFI) of polypropylene and polypropylene compositions is determined according to ISO 1 133, condition L, at 230°C and 2.16 kg.
  • Melt index (MI2) of polyethylene and polyethylene compositions is determined according to ISO 1 133, condition D, at 190°C and 2.16 kg.
  • Density is measured according to ISO 1 183 at 23°C.
  • Top load of the thermoformed cups is determined by dynamic compression of the cups at 23°C and a speed of 10 mm/min with a preload of 1 N in accordance with ISO 12048: 1994.
  • the falling weight test was performed on the thermoformed cups following ISO 6603-2:2000 from a height of 1 m at the indicated temperatures.
  • Haze was measured according to ISO 14782: 1999 on samples taken from the side wall and the bottom of the thermoformed cups.
  • Gloss was determined in accordance with ASTM-D 2457 at an angle of 45° on samples taken from the side wall and the bottom of the thermoformed cups.
  • the molecular weight distribution (MWD) is then calculated as M w /M n .
  • Xylene solubles i.e. the xylene soluble fraction
  • XS Xylene solubles
  • XS (in wt%) (Weight of the residue / Initial total weight of PP) * 300 with all weights being in the same unit, such as for example in grams.
  • the 13 C-NMR analysis is performed using a 400 MHz Bruker NMR spectrometer under conditions such that the signal intensity in the spectrum is directly proportional to the total number of contributing carbon atoms in the sample. Such conditions are well known to the skilled person and include for example sufficient relaxation time etc. In practice the intensity of a signal is obtained from its integral, i.e. the corresponding area.
  • the data is acquired using proton decoupling, 4000 scans per spectrum, a pulse repetition delay of 20 seconds and a spectral width of 26000 Hz.
  • the sample is prepared by dissolving a sufficient amount of polymer in 1 ,2,4-trichlorobenzene (TCB, 99%, spectroscopic grade) at 130°C and occasional agitation to homogenize the sample, followed by the addition of hexadeuterobenzene (CeD 6 , spectroscopic grade) and a minor amount of hexamethyldisiloxane (HMDS, 99.5+ %), with HMDS serving as internal standard.
  • TCB 1 ,2,4-trichlorobenzene
  • HMDS hexadeuterobenzene
  • HMDS hexamethyldisiloxane
  • the isotacticity is determined by 13 C-NMR analysis on the total polymer.
  • the signals corresponding to the pentads mmmm, mmmr, mmrr and mrrm are assigned using published data, for example A. Razavi, Macromol. Symp., vol. 89, pages 345-367. Only the pentads mmmm, mmmr, mmrr and mrrm are taken into consideration due to the weak intensity of the signals corresponding to the remaining pentads.
  • For the signal relating to the mmrr pentad a correction is performed for its overlap with a methyl signal related to 2, 1 -insertions. The percentage of mmmm pentads is then calculated according to
  • % mmmm AREAmmmm / (AREAmmmm + AREAmmmr + AREAmmrr +
  • AREA mrrm 100 Determination of the percentage of 2, 1 -insertions for a metallocene propylene homopolymer:
  • the signals corresponding to the 2, 1 -insertions are identified with the aid of published data, for example H.N. Cheng, J. Ewen, Makromol. Chem., vol. 190 (1989), pages 1931 -1940.
  • a first area, AREA1 is defined as the average area of the signals corresponding to 2, 1 -insertions.
  • a second area, AREA2 is defined as the average area of the signals corresponding to 1 ,2- insertions.
  • the assignment of the signals relating to the 1 ,2-insertions is well known to the skilled person and need not be explained further.
  • the percentage of 2, 1 -insertions is calculated according to
  • Melting temperatures T me it are measured on a DSC Q2000 instrument by TA Instruments based on ISO 3146. To erase the thermal history the samples are first heated to 200°C and kept at 200°C for a period of 3 minutes. The reported melting temperatures T me it are then determined with heating and cooling rates of 20°C/min.
  • - PP1 and PP2 are propylene homopolymers produced in a bulk loop reactor using a bridged 2,4-disubstituted bis-indenyl zirconocene on a silica support.
  • - PP3 is a propylene homopolymer produced in a bulk loop reactor using a Ziegler-Natta catalyst.
  • - PE1 is a polyethylene produced by copolymerization of ethylene and an a-olefin in a slurry loop reactor using a bridged bis- tetrahydroindenyl zirconocene on a a silica support. It has a melt index MI2 of 4.0 dg/min, a density of 0.960 g/cm 3 , a melting temperature T me it of 134 °C and a molecular weight distribution M w /Mn of 2.8.
  • All three polypropylenes contained an additivation of antioxidants and an acid scavenger in amounts sufficient to avoid polymer degradation during processing.
  • PP2 and PP3 contained 250 ppm of a strong nucleating agent. Further properties of PP1 , PP2 and PP3 are given in Table 1 .
  • SHEET EXTRUSION Sheet having a thickness of 1 mm was produced on a 1 m wide Reifenhauser sheet extrusion line with an upward chill roll stack having three chill rolls, a 70 mm main extruder having a ratio of length to diameter (L/D) of 33, a 50 mm side extruder having a L/D of 30, a melt pump and a coathanger die.
  • L/D length to diameter
  • 50 mm side extruder having a L/D of 30
  • melt pump and a coathanger die for the production of monolayer sheet, i.e. sheet consisting of a polypropylene layer, the same polymer was fed to both extruders.
  • the respective polypropylene composition was fed to the main extruder, the polyethylene composition to the side extruder, with both extruders being set to the same temperatures.
  • the co-extruded sheet was configured such that the polypropylene layer contacted the chill roll first. Respective thicknesses were 750 pm for the polypropylene layer and 250 pm for the polyethylene layer.
  • the so-obtained sheet was thermoformed by plug-assisted pressure forming on a Gabler Swing thermoforming machine into cups having a depth of approximately 50 mm and an inner diameter of about 85 mm at the top and of 65 to 67 mm at the bottom with a rim of 5 mm at the top using a four-fold mold. Processing conditions are given in Table 3. Mechanical properties of the thermoformed cups are given in Table 4. Table 3 - Thermoforming conditions
  • thermoforming conditions of Example 2 and comparative Example 4 show that a sheet consisting of a polypropylene produced with a metallocene-based polymerization catalyst can be thermoformed at a sheet temperature that is 10°C below that of a sheet consisting of a polypropylene produced with a Ziegler-Natta polymerization catalyst.
  • thermoformed cups which have a high melt index and was produced with a metallocene-based polymerization catalyst
  • a polypropylene which has a much lower melt flow index and was produced with a Ziegler-Natta catalyst
  • thermoformed cups are essentially the same for the polypropylene as defined in the present application (see Example 2), and a conventional polypropylene used in extrusion-thermoforming (see Example 4), particularly as the present approach of using a high melt flow index polypropylene, preferably in combination with a narrow molecular weight distribution, runs counter to what the person skilled in the art would normally do as has been explained earlier in this application.
  • the polypropylene used in Example 1 resulted in opaque cups, as can be seen from the respective optical data in Table 4.
  • these cups were also characterized by a soft touch. Such a soft touch is normally only obtainable by the addition of costly additives to the polypropylene.
  • the present invention surprisingly allows for easier and more economic production of opaque, soft touch cups.
  • Example 3 show that a polypropylene layer and a polyethylene layer may be co-extruded without any binding layer between and still result in good properties for the thermoformed article, and in consequence for the sheet as well. This allows for simplified production of sheet and thermoformed articles having a polypropylene layer and a polyethylene layer adjacent to one another.
  • thermoformed articles produced by co-extrusion of a polypropylene layer and a polyethylene layer as defined in the present application are autoclaveable and allow the packaging of food to be stored at refrigerator or freezer temperatures and heated in the same package.

Landscapes

  • Laminated Bodies (AREA)
  • Compositions Of Macromolecular Compounds (AREA)
  • Manufacture Of Macromolecular Shaped Articles (AREA)

Abstract

L'invention concerne des feuilles et des articles thermoformés comprenant une couche de polypropylène qui est constituée par une composition de polypropylène renfermant un polypropylène produit via un catalyseur de polymérisation à base de métallocène. L'invention concerne également un procédé de fabrication de telles feuilles et de tels articles thermoformés.
PCT/EP2011/070446 2010-11-18 2011-11-18 Utilisation de métallocène-polypropylène dans le thermoformage WO2012066119A2 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
EP10191731 2010-11-18
EP10191731.8 2010-11-18

Publications (2)

Publication Number Publication Date
WO2012066119A2 true WO2012066119A2 (fr) 2012-05-24
WO2012066119A3 WO2012066119A3 (fr) 2012-07-26

Family

ID=43923675

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/EP2011/070446 WO2012066119A2 (fr) 2010-11-18 2011-11-18 Utilisation de métallocène-polypropylène dans le thermoformage

Country Status (1)

Country Link
WO (1) WO2012066119A2 (fr)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0152701A1 (fr) 1983-12-27 1985-08-28 Sumitomo Chemical Company, Limited Procédé pour la fabrication de copolymères de propylène
EP0368577A2 (fr) 1988-11-04 1990-05-16 Sumitomo Chemical Company, Limited Polypropyléne crystalline et ses compositions
WO2003102069A1 (fr) 2002-05-30 2003-12-11 Ciba Specialty Chemicals Holding Inc. Polypropylenes $g(b)-cristallins

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6391467B1 (en) * 1999-07-08 2002-05-21 Exxonmobil Oil Corporation Cast film made from metallocene-catalyzed polypropylene
US20070082154A1 (en) * 2005-10-12 2007-04-12 Benoit Ambroise Multi-layer films, methods of manufacture and articles made therefrom

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0152701A1 (fr) 1983-12-27 1985-08-28 Sumitomo Chemical Company, Limited Procédé pour la fabrication de copolymères de propylène
EP0368577A2 (fr) 1988-11-04 1990-05-16 Sumitomo Chemical Company, Limited Polypropyléne crystalline et ses compositions
WO2003102069A1 (fr) 2002-05-30 2003-12-11 Ciba Specialty Chemicals Holding Inc. Polypropylenes $g(b)-cristallins

Non-Patent Citations (7)

* Cited by examiner, † Cited by third party
Title
"Plastics Additives Handbook", 2001, HANSER PUBLISHERS
A. RAZAVI, MACROMOL. SYMP., vol. 89, pages 345 - 367
BLOMENHOFER ET AL., MACROMOLECULES, vol. 38, 2005, pages 3688 - 3695
H.N. CHENG; J. EWEN, MAKROMOL. CHEM., vol. 190, 1989, pages 1931 - 1940
J.L. THRONE: "Thermoforming", 1987, CARL HANSER VERLAG
J.L. THRONE: "Understanding Thermoforming", 1999, CARL HANSER VERLAG
J.L. THRONE: "Understanding Thermoforming", 1999, CARL HANSER VERLAG, pages: 93 - 100

Also Published As

Publication number Publication date
WO2012066119A3 (fr) 2012-07-26

Similar Documents

Publication Publication Date Title
RU2530491C2 (ru) Композиция сополимера пропилена/1-гексена с широким окном тепловой сварки
US7619038B2 (en) Homogeneous polymer blend and articles therefrom
EP3189101B1 (fr) Polypropylène bimodal et leur procédé de préparation
US20120045656A1 (en) Polypropylene composition in blown film
KR20010023057A (ko) 프로필렌계 중합체 조성물 및 이로부터 제조된 필름
EP1871832B1 (fr) Films de polymeres du propylene orientes biaxialement
US20190193351A1 (en) Extrusion Blow-Molded Articles and Process for Their Production
US6593442B2 (en) Semicrystalline propylene polymer compositions with good suitability for producing biaxially oriented films
EP3950739B1 (fr) Feuille de polypropylène
EP2159253A1 (fr) Film coulé ou soufflé de polypropylène catalysé par métallocène doté de propriétés de formation de film améliorées
US11904580B2 (en) Multilayer film with improved properties
EP2501747B1 (fr) Films thermoretractables
EP4442428A2 (fr) Films et compositions de polymère recyclables
WO2012066119A2 (fr) Utilisation de métallocène-polypropylène dans le thermoformage
EP2751195B1 (fr) Composition de polypropylène ayant une rétention d'additif améliorée
US20230323101A1 (en) Polypropylene compositions
KR20120001730A (ko) 인몰드 라벨용 폴리올레핀 필름
US20220186009A1 (en) Polypropylene Compositions
WO2012066118A1 (fr) Adhérence améliorée entre couche de polypropylène et couche de polyéthylène
KR20180102577A (ko) 신디오택틱 폴리프로필렌을 포함하는 파이프

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 11784505

Country of ref document: EP

Kind code of ref document: A2

DPE1 Request for preliminary examination filed after expiration of 19th month from priority date (pct application filed from 20040101)
NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 11784505

Country of ref document: EP

Kind code of ref document: A2