One-step production of a polypropylene composition

Abstract

The present invention relates to a process for providing a polypropylene composition comprising a branched polypropylene (b-PP), a polypropylene composition as well as a film comprising the polypropylene composition.

1 . Process for providing a polypropylene composition comprising a branched polypropylene (b-PP), the process comprising the steps of:
 a) providing a polypropylene (PP) having a melt flow rate MFR 2  (230° C.) of more than 1.0 g/10 min;   b) providing a thermally decomposing free radical-forming agent,   c) providing bifunctionally unsaturated monomer(s) and/or multifunctionally unsaturated low molecular weight polymer(s),   d) providing a linear polypropylene (l-PP) having a melt flow rate MFR 2  (230° C.) of 10.0 to 50.0 g/10 min,   e) reacting the polypropylene (PP) of step a) with the thermally decomposing free radical-forming agent of step b) and the bifunctionally unsaturated monomer(s) and/or multifunctionally unsaturated low molecular weight polymer(s) of step c) obtaining thereby the branched polypropylene (b-PP), and   f) reacting the branched polypropylene (b-PP) obtained in step e) with the linear polypropylene (l-PP) of step d),   
       wherein the polypropylene composition and/or branched polypropylene (b-PP) has/have
 i) a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 of 18.0 to 35.0 g/10 min, 
 ii) a F 30  melt strength of more than 3.4 cN and a v 30  melt extensibility of more than 200 mm/s, wherein the F 30  melt strength and the v 30  melt extensibility are measured according to ISO 16790:2005. 
 
     
     
         2 . The process according to  claim 1 , wherein the polypropylene (PP) has a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 in the range from 1.0 to 18.0 g/10 min. 
     
     
         3 . The process according to  claim 1 , wherein the polypropylene (PP)
 (a) is a linear polypropylene (l-PP′); and/or   (b) is a linear polypropylene (l-PP′) having a F 30  melt strength of more than 1.0 cN and a v 30  melt extensibility of below 200 mm/s, wherein the F 30  melt strength and the v 30  melt extensibility are measured according to ISO 16790:2005.   
     
     
         4 . The process according to  claim 1 , wherein
 (a) the thermally decomposing free radical-forming agent of step b) is a peroxide and/or   (b) the bifunctionally unsaturated monomer(s) and/or multifunctionally unsaturated low molecular weight polymer(s) of step c) is/are selected from the group consisting of divinyl compounds, allyl compounds and dienes.   
     
     
         5 . The process according to  claim 1 , wherein
 (a) the linear polypropylene (l-PP) of step d) has a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 20.0 to 40.0 g/10 min, and/or   (b) the linear polypropylene (l-PP) of step d) comprises at least one additive (A) selected from the group consisting of antioxidants, metal deactivators, UV-stabilizers, antistatic agents, antifogging agents, acid scavengers, blowing agents, cling agents, lubricants, nucleating agents, slip agents, antiblocking agents and mixtures thereof, and/or   (c) the branched polypropylene (b-PP) obtained in step e) is free of additives (A).   
     
     
         6 . The process according to  claim 1 , wherein steps e) and f) are accomplished in an extruder, said extruder comprises in operation direction a first mixing zone (MZ1) and a second mixing zone (MZ2), wherein further step e) takes place in the first mixing zone (MZ1) whereas step f) takes place in the second mixing zone (MZ2). 
     
     
         7 . The process according to  claim 6 , wherein the extruder comprises in operation direction a feed-throat (FT), the first mixing zone (MZ1), the second mixing zone (MZ2) and a die (D), wherein between the first mixing zone (MZ1) and the second mixing zone (MZ2) a side feed-throat (SFT) is located, wherein further the polypropylene (PP) of step a), the thermally decomposing free radical-forming agent of step b), and the bifunctionally unsaturated monomer(s) and/or multifunctionally unsaturated low molecular weight polymer(s) of step c) are fed via the feed-throat (FT) and the linear polypropylene (l-PP) of step d) is fed via the side feed-throat (SFT). 
     
     
         8 . The process according to  claim 6 , wherein not more than 10.0 wt.-% of the total amount of the branched polypropylene (b-PP) of the polypropylene composition is produced in the second mixing zone (MZ2). 
     
     
         9 . The process according to  claim 1 , wherein 1.0 to 6.0 parts by weight of the linear polypropylene (l-PP) are added to 94.0 to 99.0 parts by weight of branched polypropylene (b-PP). 
     
     
         10 . The process according to anyone of  claim 1 , wherein the resulting polypropylene composition and/or branched polypropylene (b-PP)
 (a) has/have a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 of 19 to 30.0 g/10 min, and/or   (b) has/have a F 30  melt strength from 4.0 to 20.0 cN and a v 30  melt extensibility from 240 to 300 mm/s, wherein the F 30  melt strength and the v 30  melt extensibility are measured according to ISO 16790:2005; and/or   (c) has/have an OCS gel index of less than 2,500.   
     
     
         11 . The process according to  claim 1 , wherein the resulting polypropylene composition is prepared in a single step process. 
     
     
         12 . The process according to  claim 1 , wherein the resulting polypropylene composition further has
 (a) 95.0 to 99.0 parts by weight of the branched polypropylene (b-PP); and   (b) 1.0 to 5.0 parts by weight of the linear polypropylene (l-PP) having a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 of 10.0 to 50.0 q/10 min;   
       wherein the polypropylene composition has
 a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 18.0 to 35.0 q/10 min, and 
 an OCS gel index of less than 2,500; and 
 
       wherein the polypropylene composition and/or the branched polypropylene (b-PP) has/have a F 30  melt strength of more than 3.4 cN and a V 30  melt extensibility of more than 200 mm/s, wherein the F 30  melt strength and the v 30  melt extensibility are measured according to ISO 16790:2005. 
     
     
         13 . Polypropylene composition comprising:
 (a) 95.0 to 99.0 parts by weight of a branched polypropylene (b-PP); and   (b) 1.0 to 5.0 parts by weight of a linear polypropylene (l-PP) having a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 of 10.0 to 50.0 g/10 min;   
       wherein the polypropylene composition has
 a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 18.0 to 35.0 g/10 min, and 
 an OCS gel index of less than 2,500; and 
 
       wherein the polypropylene composition and/or the branched polypropylene (b-PP) has/have a F 30  melt strength of more than 3.4 cN and a v 30  melt extensibility of more than 200 mm/s, wherein the F 30  melt strength and the v 30  melt extensibility are measured according to ISO 16790:2005. 
     
     
         14 . Polypropylene composition according to  claim 13 , comprising
 (a) 95.0 to 99.0 parts by weight of a branched polypropylene (b-PP); and   (b) 1.0 to 5.0 parts by weight of a linear polypropylene (l-PP) having a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 25.0 to 38.0 g/10 min;   
       wherein the polypropylene composition has
 a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 19.0 to 25.0 g/10 min, and 
 an OCS gel index of less than 2,000; 
 
       and wherein further the polypropylene composition and/or the branched polypropylene (b-PP) has/have a F 30  melt strength from 4.0 to 20.0 cN and a v 30  melt extensibility from 240 to 300 mm/s, wherein the F 30  melt strength and the v 30  melt extensibility are measured according to ISO 16790:2005. 
     
     
         15 . Polypropylene composition according to  claim 13 , wherein the polypropylene composition comprises at least one additive (A) selected from the group consisting of antioxidants, metal deactivators, UV-stabilizers, antistatic agents, antifogging agents, acid scavengers, blowing agents, cling agents, lubricants, nucleating agents, slip agents, antiblocking agents and mixtures thereof. 
     
     
         16 . Film comprising the polypropylene composition according to  claim 13 . 
     
     
         17 . The process according to  claim 1 , wherein the polypropylene (PP) has a melt flow rate MFR 2  (230° C.) measured according to ISO in the range from 1.0 to 15.0 g/10 min. 
     
     
         18 . The process according to  claim 1 , wherein
 (a) the linear polypropylene (l-PP) of step d) has a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 25.0 to 38.0 g/10 min, and/or   (b) the linear polypropylene (l-PP) of step d) comprises two additives (A) selected from the group consisting of antioxidants, metal deactivators, UV-stabilizers, antistatic agents, antifogging agents, acid scavengers, blowing agents, cling agents, lubricants, nucleating agents, slip agents, antiblocking agents and mixtures thereof, and/or   (c) the branched polypropylene (b-PP) obtained in step e) is free of additives (A).   
     
     
         19 . The process according to  claim 1 , wherein 1.0 to 3.0 parts by weight of the linear polypropylene (l-PP) are added to 97.0 to 99.0 parts by weight of branched polypropylene (b-PP). 
     
     
         20 . The process according to  claim 1 , wherein the resulting polypropylene composition and/or branched polypropylene (b-PP)
 (a) has/have a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 of 19 to 30.0 g/10 min, and/or   (b) has/have a F 30  melt strength from 4.0 to 20.0 cN and a v 30  melt extensibility from 240 to 300 mm/s, wherein the F 30  melt strength and the v 30  melt extensibility are measured according to ISO 16790:2005; and/or   (d) has/have an OCS gel index of less than 2,000.   
     
     
         21 . The process according to  claim 1 , wherein the resulting polypropylene composition further has
 (a) 95.0 to 99.0 parts by weight of the branched polypropylene (b-PP); and   (b) 1.0 to 5.0 parts by weight of the linear polypropylene (l-PP) having a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 20.0 to 40.0 g/10 min;   
       wherein the polypropylene composition has
 a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 18.0 to 35.0 g/10 min, and 
 an OCS gel index of less than 2,500; and 
 
       wherein the polypropylene composition and/or the branched polypropylene (b-PP) has/have a F 30  melt strength of more than 3.4 cN and a v 30  melt extensibility of more than 200 mm/s, wherein the F 30  melt strength and the v 30  melt extensibility are measured according to ISO 16790:2005. 
     
     
         22 . The polypropylene composition according to  claim 13 , wherein the the linear polypropylene (l-PP) has a melt flow rate MFR 2  (230° C.) measured according to ISO 1133 from 20.0 to 40.0 g/10 min.