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EP-4735516-A1 - FLAME RETARDANT POLYMERIC COMPOSITIONS

EP4735516A1EP 4735516 A1EP4735516 A1EP 4735516A1EP-4735516-A1

Abstract

A polymeric composition includes 15 wt% to 95 wt% of a non-polar ethylene-based polymer based on the total weight of the polymeric composition; 0 wt% to 35 wt% of a polar ethylene-based polymer based on the total weight of the polymeric composition; and 5 wt% to 50 wt% of an intumescent flame-retardant mixture based on the total weight of the polymeric composition. The intumescent flame-retardant mixture includes piperazine pyrophosphate and from 15 wt% to 55 wt% of a phosphoric acid compound based on the total weight of the intumescent flame-retardant mixture.

Inventors

  • CHAUDHARY, BHARAT I.
  • LIM, CHONGSOO
  • COGEN, JEFFREY M.
  • TAPPER, Richard I.

Assignees

  • Dow Global Technologies LLC

Dates

Publication Date
20260506
Application Date
20240626

Claims (12)

  1. 1. A polymeric composition, comprising: 5 wt% to 95 wt% of a non-polar ethylene-based polymer based on the total weight of the polymeric composition; 0 wt% to 35 wt% of a polar ethylene-based polymer based on the total weight of the polymeric composition; and 5 wt% to 90 wt% of an intumescent flame-retardant mixture based on the total weight of the polymeric composition, wherein the intumescent flame -retardant mixture comprises piperazine pyrophosphate and from 15 wt% to 55 wt% of a phosphoric acid compound based on the total weight of the intumescent flame-retardant mixture.
  2. 2. The polymeric composition of claim 1, wherein a density of the non-polar ethylenebased polymer is 0.930 g/cc or less and the non-polar ethylene-based polymer is linear or substantially linear.
  3. 3. The polymeric composition of any one of claims 1 and 2, wherein the polymeric composition is free of a polar ethylene-based polymer.
  4. 4. The polymeric composition of any one of claims 1-3, wherein the polar ethylene-based polymer is present in the composition in an amount of 0.1 wt% to 35 wt% based on the total weight of the polymeric composition.
  5. 5. The polymeric composition of any one of claims 1-4, further comprising: 0.1 wt% to 50 wt% of a halogen free flame retardant based on the total weight of the polymeric composition.
  6. 6. The polymeric composition of any one of claims 1-5, wherein the polymeric composition comprises from 5 wt% to 35 wt% of the intumescent flame-retardant mixture.
  7. 7. The polymeric composition of any one of claims 1-5, wherein the polymeric composition comprises from 7 wt% to 31 wt% of the intumescent flame-retardant mixture.
  8. 8. The polymeric composition of any one of claims 1-7, wherein the intumescent flameretardant mixture comprises from 25 wt% to 45 wt% of phosphoric acid compound based on the total weight of the intumescent flame -retardant mixture.
  9. 9. The polymeric composition of any one of claims 1-8, wherein the phosphoric acid compound is selected from the group consisting of melamine polyphosphate, ammonium polyphosphate, or combinations thereof.
  10. 10. The polymeric composition of any one of claims 1-9, wherein the intumescent flameretardant mixture comprises a flame-retardant synergist comprising a metal oxide.
  11. 11. The polymeric composition of any one of claims 1-10, wherein the polymeric composition exhibits a peak heat release rate of 350 kW/m 2 or less.
  12. 12. The polymeric composition of any one of claims 1-11, wherein the polymeric composition exhibits a tensile elongation of 75% or greater and the polymeric composition exhibits a density of 1.7 g/cc or less.

Description

FLAME RETARDANT POLYMERIC COMPOSITIONS BACKGROUND Field of the disclosure The present disclosure relates to polymeric compositions, and more specifically to filled flame retardant polymeric compositions. Introduction Jacket and/or insulation layers of wires and cables utilized in structures often must exhibit certain flame retardancy properties. Thermoplastic ethylene-based polymers (also known as polyethylenes) are often utilized as the base polymers in the compositions of such jackets or insulations when incorporating high levels of halogen-free flame retardant (“HFFR’") fillers in such materials. The HFFR fillers may be metal hydroxides or a variety of other materials and are typically polar. Typically the base thermoplastic ethylene-based polymer of the polymeric composition is polar (such as ethylene-vinyl acetate copolymer or ethylene-ethyl acrylate copolymer). The use of a polar ethylene-based polymer serves a dual benefit of assuring sufficient compatibility of the HFFR filler in the polymeric composition, and also providing a material to the polymeric composition that has a lower enthalpy of combustion than a non-polar ethylene-based polymer as described in the following publication: Cogen, J. M., Chaudhary, B. I., Ghosh-Dastidar, A., Sun, Y. and Wasserman, S. H., “Flame Retardant Aspects of Crosslinked Polyethylene (XLPE)", In: Jince Thomas, Sabu Thomas and Zakiah Ahmad (eds.), Crosslinkable Polyethylene - Manufacture, Properties, Recycling and Applications, Chapter 9. Springer, 2021. pp. 211-245. For example, polyethylene homopolymer is reported to have enthalpy of combustion of 48 kJ/g, higher than that of polar ethylene-based polymers such as ethylene vinyl acetate copolymers (38 kJ/g or 42 kJ/g at vinyl acetate contents of 40 wt% and 25 wt%, respectively) or ethylene ethyl acrylate copolymers (43 kJ/g at ethyl acrylate content of 25 wt%). The lower the heat of combustion of a material, the lower the thermal energy produced. Thus, the peak heat release rate (“PHRR”) measured by cone calorimetry of an ethylene vinyl acetate copolymer (having 18 wt% vinyl acetate content) is about 19% lower than that of polyethylene homopolymer. Such a feature is advantageous as the polymeric compositions used to make flame-retardant wires and cables desirably need to exhibit a PHRR of 350 kW/m2 or less. In addition to the flame retardancy of the wires and cables, the densities of the polymeric compositions are also important. By decreasing the density of the jacket and/or insulation, the wire and cable products are manufactured, transported, and installed with greater efficiency and cost effectiveness. One approach for creating a lighter weight product is to use an intumescent type flame retardant as HFFR filler as described by the above-noted publication. An intumescent flame retardant is one that, when exposed to heat, is rapidly transformed through sublimation, and expands many times its original thickness to form a stable, carbonaceous char. Intumescent flame retardants are typically based on phosphorus and nitrogen compounds which decompose to form an insulating foam layer. These intumescent flame retardants are comprised of an acid source (such as ammonium polyphosphate), foaming agent (such as melamine) and a charring agent (such as pentaerythritol). In some cases, all three required functionalities (i.e., phosphorus, nitrogen and carbon sources) are delivered through the use of a single compound (such as piperazine pyrophosphate). Melamine polyphosphate is another example of an intumescent flame retardant. Intumescent flame retardants may be used in lower quantities than other HFFR counterparts such as metal hydroxides (hydrates) which allows for wires and cables produced therefrom to be lighter in weight due to the lower densities of the polymeric compositions. Typically, a density of 1.40 grams per cubic centimeter (“g/cc”) or less of the polymeric composition would especially be considered an improvement over the traditional metal hydroxide filled HFFR systems (while yielding a PHRR of 350 kW/m2 or less), with a density as high as 1.7 g/cc being considered acceptable. Although intumescent flame retardants offer an advantage in terms of light weighting, the use of intumescent flame retardants poses several issues. First, intumescent flame retardants are typically confined in practice to compositions based on polypropylene and not based on polyethylene. For example, United States Patent Application Publication number 2003/0088000A1 disclose the use of intumescent compounds, but all of the examples rely on systems comprising 72 weight percent of polypropylene or greater and no polyethylene. As such, it is unknown what composition of intumescent, level of intumescent loading, and ethylene-based polymer composition would provide effective flame retardancy and lightweighting benefits to polyethylene systems while yielding satisfactory mechanical properties. In view of the foregoing, it would be surprising