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EP-4735521-A1 - FLUORINE-FREE AND SILICONE-FREE POLYMER PROCESSING AIDS

EP4735521A1EP 4735521 A1EP4735521 A1EP 4735521A1EP-4735521-A1

Abstract

The present invention relates to polymer processing aid compositions for polyolefins, their methods of manufacture and articles made from the compositions as well as use of the compositions for the removal or reduction of sharkskin melt fracture or reduction in the formation of die lip build-up. Compositions of the present invention may also be substantially free of fluorine and in some embodiments substantially free of siloxane.

Inventors

  • CHARLTON, J. Zachariah
  • SCHNEIDER, Alyssa
  • AREFI, Ahmad
  • Giammaria, Paul Marco
  • GRITSICHINE, Vladimir
  • TZOGANAKIS, COSTAS

Assignees

  • Ingenia Polymers International S.A.

Dates

Publication Date
20260506
Application Date
20240702

Claims (15)

  1. 1. Use of a first polyester or polyester copolymer selected from the group comprising: polyflactic acid), polyhydroxyalkanoate, polyhydroxyalkanoate copolymers, polyfbutylene adipate terephthalate), as a polymer processing aid to reduce or remove melt fracture or die lip build-up in an extrudable polyolefin composition, wherein the polymer processing aid is used in an amount of from 0.01 to 1.0 weight%, based on the total weight of the extrudable polyolefin composition.
  2. 2. A method for reducing or removing melt fracture or die lip build-up in an extrudable polyolefin extrusion process comprising using a polyester or polyester copolymer selected from the group comprising: polyflactic acid), polyhydroxyalkanoate, polyhydroxyalkanoate copolymers, polyfbutylene adipate terephthalate), as a polymer processing aid wherein the polymer processing aid is used in an amount of from 0.01 to 1.0 weight%, based on the total weight of the polyolefin composition.
  3. 3. An extrudable composition comprising a polyolefin; and a polymer processing aid which is present in an amount of from 0.01 to 1.0 weight-% based on the total weight of the polyolefin composition, and wherein the polymer processing aid comprises a first polyester or polyester copolymer selected from the group comprising: polyflactic acid), polyhydroxyalkanoate, polyhydroxyalkanoate copolymers, polyfbutylene adipate terephthalate),.
  4. 4. A masterbatch composition comprising a polyolefin; and a polymer processing aid which is present in an amount of from 1 to 45 weight-% based on the total weight of the polyolefin composition, and wherein the polymer processing aid comprises a first polyester or polyester copolymer selected from the group comprising: polyflactic acid), polyhydroxyalkanoate, polyhydroxyalkanoate copolymers, polyfbutylene adipate terephthalate).
  5. 5. The use, method or composition of any preceding claim, further comprising a second polyester or polyester copolymer selected from the group comprising: polyflactic acid), polyhydroxyalkanoate, polyhydroxyalkanoate copolymers, polyfbutylene adipate terephthalate), as a processing aid, the second polyester or polyester copolymer having a higher MFR than the first polyester or polyester copolymer, and wherein the first and second polyester or polyester copolymer are used in a combined amount of from 0.01 to 1.0 weight%, based on the total weight of an extrudable polyolefin composition or in a combined amount of from 1 to 45 weight % of a masterbatch composition.
  6. 6. The use, method or composition of any preceding claim, wherein the polymer processing aid is substantially free of fluorine and/or substantially free of siloxane.
  7. 7. The use, method or composition of any preceding claim, wherein the first polyester or polyester copolymer has a molecular weight of greater than 5,000 g/mol.
  8. 8. The use, method or composition of any preceding claim, wherein both the first and second polyester or polyester copolymer are polyflactic acid).
  9. 9. The use, method or composition of claim 8, wherein the polyflactic acid) comprises greater than 80% of the L-isomer of lactic acid or lactide monomer.
  10. 10. The use, method or composition of any of claims 1 to 7, wherein the polyhydroxyalkanoate and polyhydroxyalkanoate copolymers are selected from the group comprising: poly(3-hydroxybutyrate), Poly(3-hydroxybutyrate-co-3-hydroxyvalerate), poly(3- hydroxybutyrate-co-4-hydroxybutyrate).
  11. 11. The use, method or composition of any of claims 1 to 10 wherein the first polyester or polyester copolymer and the second polyester or polyester copolymer are present in the polymer processing aid in a ratio of from about 1:10 to about 10:1.
  12. 12. The use, method or composition as claimed in in any preceding claim further comprising 0.01 to 45 weight-% of the total composition of a synergist selected from a polyfoxy alkylene) or a polymeric liquid phosphite antioxidant.
  13. 13. The use, method or composition as claimed in any preceding claim, wherein the polyolefin is selected from a polyethylene, including a high-density polyethylene, linear low- density polyethylene or a low-density polyethylene, or a polypropylene, including a homopolymer polypropylene, random copolymer polypropylene, or a heterophasic impact copolymer polypropylene, or a combination thereof.
  14. 14. A use, method, or composition as claimed in any of claim 4 to 13, wherein the masterbatch composition further comprises one or more polymer additives selected from the following: hindered phenols, phosphites, metal stearates, hydrotalcites, zinc oxide, slip, antiblocking, anti-static additives, and combinations thereof, wherein the one or more polymer additives are present in a combined amount of from 5 to 75 weight %, based on the total weight of the polyolefin masterbatch composition.
  15. 15. An extruded polyolefin product whenever produced using the composition, method or uses of any of claims 1 to 14.

Description

Fluorine-free and Silicone-free Polymer Processing Aids Technical Field [0001] The present invention relates to the application of polyesters and polyester copolymers as polymer processing aids (PPAs) in polyolefin extrusion, including film extrusion. Background [0002] Industrial polyolefin melt processes - including blown film, cast film, sheet extrusion, profile extrusion, blow molding, wire and cable extrusion coating, and fibre spinning - desire high throughputs in order to reduce costs associated with such processing. However, elevating polyolefin extrusion rates above a critical wall shear stress can lead to the onset of flow instabilities which manifest themselves as distortions of the extruded product. Hatzikiriakos, S. G., & Migler, K. B. (2012), Polymer Processing Additives for Melt Fracture Control in "Applied Polymer Rheology: Polymeric Fluids with Industrial Applications", First Edition, pp 29-58, describes a range of melt extrusion instabilities observed in industry. Above a critical volumetric flow rate, polyolefin extrusions exhibit distortions which increase in severity as the flow rate increases. These distortions are collectively referred to as "melt fracture". Above a first critical shear stress the polyolefin extrudate exhibits "surface melt fracture", also called "sharkskin" . Sharkskin appears as a regular pattern of surface roughness causing haze which is undesirable and limits the rate of extrusion. Extrusion at still higher rates can lead to a stick-slip instability or "oscillating melt fracture". Extrusion at even higher rates leads to gross, irregular distortions in the extrudate known as "gross melt fracture" . [0003] "Polymer Processing Aids" ("PPAs") are well known to those skilled in the art of polyolefin extrusion and film processing. The addition of low concentrations of PPAs to the polyolefin melt increases the critical shear stress at which sharkskin occurs, allowing for higher throughput rates without the onset of sharkskin. Heretofore, fluoroelastomers and fluoroplastics (collectively "fluoropolymers") have been the established PPA solution to sharkskin in polyolefin extrusion processes. [0004] US Patent No. 3,125,547 discloses compositions of 0.005 to 2 wt.-% fluoropolymer in polyolefins. The compositions are effective in removing sharkskin from film and tube extrusions as compared to extrusions of the same polyolefins absent the fluoropolymer. [0005] US Patent No. 4,855,360 discloses polyolefin compositions containing minor amounts of fluoropolymers in combination with a poly(oxyalkylene) polymer. Preferred poly(oxyalkylene) polymers disclosed are polyethylene glycols (PEG; CAS#: 25322-68-3) with a molecular weight of 1,000 to 20,000 g/mol. Such compositions show a synergistic effect of the poly(oxyalkylene) with the fluoropolymers of the invention. The examples of that document demonstrate that the combination of fluoropolymer and PEG shift the onset of melt fracture to higher shear rates than for fluoropolymer or PEG alone, reduce the time to remove melt fracture in blown film processing at a given apparent shear rate and reduce the pressure drop across the blown film die. The compositions allow lower use of fluoropolymer with poly(oxyalkylene) as compared to the use of fluoropolymer alone. [0006] US Patent No. 6,642,310 discloses improved PPA efficiency through the use of dispersed fluoropolymer particles of a minimum particle size of 2 micron and the use of interfacial agents to help achieve the target particle size. Silicone-polyether, aromatic polyester and aliphatic polyesters including polylactic acid (PLA) and polycaprolactone (PCL; CAS#: 24980-41-4), among other materials are disclosed as useful interfacial agents. The use of PCL as an interfacial agent with improved temperature resistance, compared to poly(oxyalkylene), is disclosed. [0007] Fluoropolymer PPAs, often formulated in combination with a synergist, are effective at low concentrations. In addition to delaying the onset of sharkskin to higher extrusion rates, such compositions can reduce extrusion pressure and extruder torque at a given output and can help reduce die lip build up (also called die drool). However, the use of fluoropolymers as polymer processing aids is now undesirable due to regulatory and market developments requiring the removal of per- and poly-fluoroalkyl substances ("PFAS") from polyolefins. Thus, there is a need for a fluorine-free alternative PPA to eliminate sharkskin melt fracture. [0008] US Patent No. 4,535,113 discloses a composition of a polyolefin and a silicone additive. The silicone additive is a polyfdimethyl siloxane) ("PDMS") copolymer where the comonomer consists of a siloxane substituted with at least one pendant ethylene oxide, vicinal epoxy or amino group in a concentration sufficient to improve optical or mechanical properties. The compositions are shown to reduce melt fracture and pin striping where the silicone additive is present at 0.05% of the compositi