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EP-4556499-B1 - MULTIMODAL POLYPROPYLENE HOMOPOLYMER FOR FILM APPLICATIONS

EP4556499B1EP 4556499 B1EP4556499 B1EP 4556499B1EP-4556499-B1

Inventors

  • WANG, JINGBO
  • GAHLEITNER, MARKUS
  • BERNREITNER, KLAUS
  • NIEDERSUESS, PETER
  • ORTNER, STEFAN
  • LESKINEN, PAULI
  • Aho, Jani

Dates

Publication Date
20260506
Application Date
20231117

Claims (15)

  1. A polypropylene composition comprising: (A) 99.0 to 99.9999 wt.-%, based on the total weight of the composition, of a trimodal polypropylene homopolymer (tPPH), the trimodal polypropylene homopolymer (tPPH) comprising (A-1) 20 to 60 wt.-%, based on the total weight of the tPPH, of a first polypropylene homopolymer fraction (PPH1) having • a melt flow rate MFR 2 , determined according to ISO 1133 at 230°C and a load of 2.16 kg, in the range of 1.0 to 20 g/10 min, (A-2) 30 to 60 wt.-%, based on the total weight of the tPPH, of a second polypropylene homopolymer fraction (PPH2) having • a melt flow rate MFR 2 , determined according to ISO 1133 at 230°C and a load of 2.16 kg, in the range of 1.0 to 20 g/10 min, (A-3) 1 to 15 wt.-%, based on the total weight of the tPPH, of a third polypropylene homopolymer fraction (PPH3) having • a melt flow rate MFR 2 , determined according to ISO 1133 at 230°C and a load of 2.16 kg, in the range of 0.1 to 5.0 g/10 min, whereby the MFR 2 of the first, the second and the third polypropylene homopolymer fraction are different from each other and whereby MFR 2 of (PPH1) > MFR 2 of (PPH2) > MFR 2 (PPH3); (B) 0.0001 to 1.0 wt.-%, based on the total weight of the polypropylene composition, of an alpha nucleating agent, whereby the polypropylene composition has a melt flow rate MFR 2 , determined according to ISO 1133 at 230°C and a load of 2.16 kg, in the range of 0.5 to 15 g/10 min, a crystallization temperature, determined with DSC according to ISO 11357, in the range of 125 to 140°C and a flexural modulus, determine according to ISO 178 on injection molded specimens of 80 x 10 x 4 mm 3 , prepared at 230°C in accordance with EN ISO 19069-2 in the range of 1950 to 2800 MPa.
  2. The polypropylene composition according to claim 1, wherein the polypropylene composition has a flexural modulus, determined in a 3-point-bending according to ISO 178 on injection molded specimens of 80 x 10 x 4 mm 3 , prepared at a melt temperature of 230°C in accordance with EN ISO 19069-2, of the polypropylene in the range of 2000 to 2800 MPa, preferably 2100 to 2500 MPa and/or a melting temperature (Tm), determined by differential scanning calorimetry (DSC), in the range of 162 to 175°C, preferably 163 to 172°C, more preferably 165 to 170°C.
  3. The polypropylene composition according to claim 1 or 2, wherein the composition has a melt flow rate MFR 2 (230°C, 2.16kg, ISO 1133) in the range from 1.0 to 10 g/10 min, preferably from 2.0 to 8.0 g/10 min and/or a crystallization temperature Tc, determined by differential scanning calorimetry (DSC) in the range of 130 to 140°C, preferably 130 to 135°C.
  4. The polypropylene composition according to any of the preceding claims, wherein the amount of the trimodal polypropylene homopolymer (tPPH) is in the range of 99.3 to 99.99 wt.-%, preferably 99.5 to 99.95 wt.-% and the amount of the alpha nucleating agent is in the range of 0.01 to 0.7 wt.-%, preferably 0.05 to 0.5wt.-%, both based on the total weight of the polypropylene composition.
  5. The polypropylene composition according to any of the preceding claims, wherein the trimodal polypropylene homopolymer (tPPH) consists of (A-1) 30 to 55 wt.-0%, based on the total weight of the tPPH, of the first polypropylene homopolymer fraction (PPH1) (A-2) 40 to 60 wt.-%, based on the total weight of the tPPH, of the second polypropylene homopolymer fraction (PPH2) and (A-3) 3 to 12 wt.-%, based on the total weight of the tPPH, of the third polypropylene homopolymer fraction (PPH3), the sum of the amounts of PPH1, PPH2 and PPH3 add up to 100 wt.-%, preferably the trimodal polypropylene homopolymer (tPPH) consists of (A-1) 40 to 52 wt.-%, based on the total weight of the tPPH, of the first polypropylene homopolymer fraction (PPH1) (A-2) 45 to 58 wt.-%, based on the total weight of the tPPH, of the second polypropylene homopolymer fraction (PPH2) and (A-3) 5 to 10 wt.-%, based on the total weight of the tPPH, of the third polypropylene homopolymer fraction (PPH3), the sum of the amounts of PPH1, PPH2 and PPH3 add up to 100 wt.-%.
  6. The polypropylene composition according to any of the preceding claims, wherein the first polypropylene homopolymer fraction (PPH1) has a melt flow rate MFR 2 (230°C, 2.16 kg, ISO 1133-1) in the range of 2.0 to 15 g/10 min, preferably in the range of 5.0 to 12.0 g/10 min, the second polypropylene homopolymer fraction (PPH2) has a melt flow rate MFR 2 (230°C, 2.16 kg, ISO 1133-1) in the range of 1.5 to 12 g/10 min, preferably in the range of 2.0 to 8.0 g/10 min and the third polypropylene homopolymer fraction (PPH3) has a melt flow rate MFR 2 (230°C, 2.16 kg, ISO 1133-1) in the range of 0.2 to 3.0 g/10 min, preferably in the range of 0.3 to 1.5 g/10 min, whereby the MFR 2 of the first, the second and the third polypropylene homopolymer fraction are different from each other and whereby MFR 2 of (PPH1) > MFR 2 of (PPH2) > MFR 2 (PPH3).
  7. The polypropylene composition according to any of the preceding claims, wherein the final MFR 2 (230°C, 2.16kg, ISO 1133-1) of the trimodal polypropylene homopolymer (tPPH) is in the range of 1.0 to 12 g/10 min, preferably in the range of 2.0 to 8.0 g/10 min and/or wherein the trimodal polypropylene homopolymer (tPPH) has a xylene cold soluble (XCS) content, determined according to ISO 16152; at 25 °C of less than 3.5 wt.-%, preferably 3.0 wt.-% or lower and more preferably 2.9 wt.-% or lower, respectively in the range of 0.5 to less than 3.5 wt.-%, more preferably 1.0 to 3.0 wt.-% and even more preferred from 1.5 to 2.9 wt.-%.
  8. The polypropylene composition according to any of the preceding claims, wherein the trimodal polypropylene homopolymer (tPPH) of the polypropylene composition is prepared by a multistage polymerization process in the presence of a Ziegler-Natta catalyst (ZN-C) comprising a) compounds (TC) of a transition metal of Group 4 to 6 of the IUPAC Periodic Table of Elements, a Group 2 metal compound (MC) and an internal donor (ID), wherein said internal donor (ID) is a non-phthalic compound, b) a co-catalyst (Co), and c) optionally an external donor (ED).
  9. The polypropylene composition according to claim 8, wherein the internal donor (ID) is selected from the group consisting of malonates, maleates, succinates, glutarates, benzoates and derivatives, each optionally substituted, and/or mixtures thereof, preferably from optionally substituted citraconates.
  10. The polypropylene composition according to any of the preceding claims, wherein the trimodal polypropylene homopolymer (tPPH) is post-reactor nucleated with at least one alpha-nucleating agent.
  11. The polypropylene composition according to any of the preceding claims, wherein the at least one alpha-nucleating agent is selected from bicyclo (2.2.1) heptane-2,3-dicarboxylic acid, di-sodium salt, hydroxy-bis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo-[d,g]-dioxa-phoshocin-6-oxidato] aluminium, metal salts of 2,2'-methylene bis(4,6-di-tert-butylphenyl)phosphat, preferably sodium-2,2'-methylene-bis(4,6-di-t-butylphenyl) phosphate, aluminium-hydroxy-bis[2,2'-methylene-bis(4,6-di-t-butyl-phenyl)-phosphate], 2,2'- methylene bis-(2,6-di-tert. butylphenyl) phosphate lithium salt, sorbitol-based nucleating agents, preferably di(alkylbenzylidene)sorbitols like 1,3:2,4-25 dibenzylidene sorbitol, 1,3:2,4-di(4-methylbenzylidene) sorbitol, 1,3:2,4-di(4- ethylbenzylidene) sorbitol and 1,3:2,4-Bis(3,4-dimethylbenzylidene) sorbitol, as well as nonitol derivatives, preferably 1,2,3-trideoxy-4,6;5,7-bis-O-[(4-propylphenyl)methylene] nonitol, and benzene-trisamides preferably substituted 1,3,5-benzenetrisamides as N,N',N"-tris-tert-butyl-1,3,5- benzenetricarboxamide, N, N', N"-tris-cyclohexyl-1,3,5-benzene-tricarboxamide and N-[3,5-bis-(2,2-dimethyl-propionylamino)-phenyl]-2,2-dimethyl-propionamide, wherein metal salts of 2,2'-methylene bis(4,6-di-tert-butylphenyl)phosphat, like 2,2'- methylene bis-(2,6-di-tert. butylphenyl) phosphate lithium salt (e.g. NA-71), bicyclo (2.2.1) heptane-2,3-dicarboxylic acid, di-sodium salt, hydroxy-bis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo-[d,g]-dioxa-phoshocin-6-oxidato] aluminium are particularly preferred.
  12. The polypropylene composition according to claim 11, wherein the at least one alpha nucleating agent is/are selected from the group consisting of 2,2'- methylene bis-(2,6-di-tert. butylphenyl) phosphate lithium salt, hydroxy-bis[2,4,8,10-tetrakis(1,1-dimethylethyl)-6-hydroxy-12H-dibenzo-[d,g]-dioxa-phoshocin-6-oxidato] aluminium and bicyclo (2.2.1) heptane-2,3-dicarboxylic acid, di-sodium salt.
  13. Use of the polypropylene composition according to any of the preceding claims for the production of films, especially blown films.
  14. A film, preferably a blown film, comprising at least 70.0 wt.-%, preferably comprising at least 80.0 wt.-%, more preferably comprising at least 90.0 wt.-%, still more preferably comprising at least 95.0 wt.-%, yet more preferably comprising at least 99.0 wt.-%, of the polypropylene composition according to any of the preceding claims 1 to 9.
  15. Blown film according to claim 14, the blown film having a tensile modulus in machine direction, as determined in accordance with ISO 527-3 on a 50 µm blown film, of from 1700 to 2900 MPa, more preferably from 1800 to 2600 MPa, and most preferably from 1900 to 2400 MPa and a haze value, as determined in accordance with ASTM D1003 on a 50 µm blown film, of from 0 to 25%, more preferably from 5 to 20%, and most preferably from 10 to 18%.

Description

Background art The present invention relates to a multimodal polypropylene homopolymer for film applications, a process for its production, films comprising the multimodal polypropylene homopolymer and its use for the production of films, preferably blown films. Propylene homopolymers are very well known and quite often used in the field of film making. In this technical area polymers are required which combine high transparency, respectively low haze and high stiffness. However it is demanding to fulfill all the required demands with one polymer since the improvement of one property is paid on the expense of another property. In the art, it is well known in this respect to improve the optical properties of a polypropylene composition by adding specific nucleating agents, also designated as clarifiers. EP2514770A1 discloses a polypropylene composition with very high melt flow rate MFR2 measured according to ISO 1133 (230 °C, 2.16 kg load) of at least 50 g/10 min, which is preferably based on a polypropylene homopolymer, produced in the presence of a phthalate containing Ziegler-Natta catalyst. The composition used in moulding and particularly the automotive business where injection moulding is the preferred conversion-process and where good mechanical properties and high thermal stability is required. The polypropylene homopolymer is composed of 3 intermediate polypropylenes, wherein, according to the experimental part, the first intermediate polypropylene has a MFR2 of at least 255 g/10 min, the second intermediate polypropylene has a MFR2 of at least 41 g/10 min and the third intermediate polypropylene has a MFR of at least 5 g/10 min, in order to achieve the desired high MFR2 of the final polypropylene. Haze is not mentioned in EP2514770A1, and a polypropylene of such high MFR2 would not be suitable for producing films. EP3945112A describes in-reactor, high flow trimodal PP homopolymers with balanced mechanical property profile produced with a non-phthalate Ziegler-Natta catalyst, which are alpha-nucleated with poly(vinyl cyclohexane) (PVCH) using the BNT technology. The design of the homopolymers produced in the experimental part differs. Inventive Examples 1 and 2 are the only ones, where the MFR2 of the 3 homopolymer fractions decreases from PP1 >PP2>PP3, but PP1 and PP2 both have a MFR2 of above 300 g/10 min and the final MFR2 of these two examples is above 200 g/10 min. No films have been prepared, also because the MFR2 was too high for that. The tensile modulus has been determined on injection moulded specimens, and haze is not mentioned at all. Although compositions based on trimodal PP homopolymers have already been described in the prior art, there was still the need to find trimodal polypropylene homopolymer based compositions, which are suitable for producing films, especially blown films, and which combine high transparency, respectively low haze and high stiffness. It has now been found that such compositions can be achieved by a specific polymer design of the polypropylene homopolymers together with proper external (post-reactor) nucleation. Summary of the Invention Thus, the present invention is in a first aspect related to a polypropylene composition comprising: (A) 99.0 to 99.9999 wt.-%, based on the total weight of the composition, of a trimodal polypropylene homopolymer (tPPH), the trimodal polypropylene homopolymer (tPPH) comprising (A-1) 20 to 60 wt.-%, based on the total weight of the tPPH, of a first polypropylene homopolymer fraction (PPH1) having a melt flow rate MFR2, determined according to ISO 1133 at 230°C and a load of 2.16 kg, in the range of 1.0 to 20 g/10 min,(A-2) 30 to 60 wt.-%, based on the total weight of the tPPH, of a second polypropylene homopolymer fraction (PPH2) having a melt flow rate MFR2, determined according to ISO 1133 at 230°C and a load of 2.16 kg, in the range of 1.0 to 20 g/10 min,(A-3) 1 to 15 wt.-%, based on the total weight of the tPPH, of a third polypropylene homopolymer fraction (PPH3) having a melt flow rate MFR2, determined according to ISO 1133 at 230°C and a load of 2.16 kg, in the range of 0.1 to 5.0 g/10 min, whereby the MFR2 of the first, the second and the third polypropylene homopolymer fraction are different from each other and whereby MFR2 of (PPH1) > MFR2 of (PPH2) > MFR2 (PPH3);(B) 0.0001 to 1.0 wt.-%, based on the total weight of the polypropylene composition, of an alpha nucleating agent, whereby the composition hasa melt flow rate MFR2, determined according to ISO 1133 at 230°C and a load of 2.16 kg, in the range of 0.5 to 15 g/10 min,a crystallization temperature, determined with DSC according to ISO 11357, in the range of 125 to 140°C and a flexural modulus, determine according to ISO 178 on injection molded specimens of 80 x 10 x 4 mm3, prepared at a melt temperature of 230°C in accordance with EN ISO 19069-2 in the range of 1950 to 2800 MPa.In a second aspect of the invention, the trimodal polypropylene homopolymer (tPPH) of th