Roofing membrane compositions based on a metallocene-catalyzed alpha-olefin polyethylene

Patent metadata

Field	Value
Publication number	US-12540236-B2
Application number	US-202318127803-A
Country	US
Kind code	B2
Filing date	Mar 29, 2023
Priority date	Mar 29, 2023
Publication date	Feb 3, 2026
Grant date	Feb 3, 2026

Abstract

Provided is a roofing membrane composition comprising metallocene-catalyzed alpha-olefin polyethylene and a random polypropylene copolymer. The polymer blend is quite useful in a roofing membrane which exhibits excellent performance. The excellent performance is particularly evident in the mechanical properties and thermal properties of the roofing membrane.

First claim

What is claimed is:

1 . A roofing membrane composition comprising:
a) from 40 wt % to 70 wt % of a polymer blend composition consisting of:
(i) from 50 to 80 wt % of a metallocene-catalyzed alpha-olefin polyethylene and
(ii) from 20 to 50 wt % of a random polypropylene copolymer;
b) at least one flame retardant; c) at least one ultraviolet stabilizer; and d) at least one pigment.

2 . The roofing membrane composition of claim 1 , wherein the polymer blend composition of a) comprises from 55 to 65 wt % of the roofing membrane composition.

3 . The roofing membrane composition of claim 2 , wherein the polymer blend composition of a) comprises from 60 to 64 wt % of the roofing membrane composition.

4 . The roofing membrane composition of claim 2 , wherein the polymer blend composition of a) comprises about 63.5 wt % of the roofing membrane composition.

5 . The roofing membrane composition of claim 1 , wherein the metallocene-catalyzed alpha-olefin polyethylene consists of from 57 to 65 wt % of the polymer blend composition in a).

6 . The roofing membrane composition of claim 1 , wherein the metallocene-catalyzed alpha-olefin polyethylene consists of from 59 to 61 wt % of the polymer blend composition in a).

7 . The roofing membrane composition of claim 1 , wherein the metallocene-catalyzed alpha-olefin polyethylene is a LLDPE.

8 . The roofing membrane composition of claim 1 , wherein the metallocene-catalyzed alpha-olefin polyethylene is a VLDPE.

9 . The roofing membrane composition of claim 1 , wherein the flame retardant comprises 10 to 40 wt % of the composition.

10 . The roofing membrane composition of claim 9 , wherein the flame retardant comprises 25 to 40 wt % of the composition.

11 . The roofing membrane composition of claim 1 , wherein the pigment comprises from 3 to 6 wt % of the composition.

12 . The roofing membrane composition of claim 11 , wherein the pigment comprises TiO 2 .

13 . The roofing membrane composition of claim 1 , wherein the UV stabilizer comprises about 2 to 7 wt % of the composition.

14 . The roofing membrane composition of claim 13 , wherein the UV stabilizer comprises about 5 wt % of the composition.

15 . The roofing membrane composition of claim 1 , comprising calcium carbonate.

16 . The roofing membrane composition of claim 1 , wherein the flame retardant comprises calcium carbonate.

17 . The roofing membrane composition of claim 16 , wherein calcium carbonate comprises at least 27 wt % of the membrane composition.

18 . The roofing membrane composition of claim 17 , wherein the amount of calcium carbonate comprises at least about 30 wt % of the membrane composition.

19 . The roofing membrane composition of claim 1 , wherein the composition exhibits improved heat aging properties compared to a membrane composition comprising an in-reactor blend resin.

20 . A roofing membrane comprising the membrane composition of claim 1 .

21 . A roof comprising a roofing membrane having a composition comprising:
a) from 40 wt % to 70 wt % of a polymer blend composition consisting of:
(iii) from 50 to 80 wt % of a metallocene-catalyzed alpha-olefin polyethylene and
(iv) from 20 to 50 wt % of a random polypropylene copolymer;
b) at least one flame retardant; c) at least one ultraviolet stabilizer; and d) at least one pigment.

22 . The roof of claim 21 , wherein the roofing membrane is fixed over base roofing by adhesive material, ballasted material, spot bonding, or mechanical spot fastening.

23 . The roof of claim 22 , wherein the roofing membranes have been installed by mechanical fasteners and plates placed along an edge sheet and fastened through the membrane and into roof decking.

24 . The roof of claim 23 , wherein adjoining sheets of roofing membrane are overlapped so as to cover the fasteners and plates and joined together by a hot air weld.

25 . A method of preparing a roofing membrane, which comprises physically blending the components comprising:
a) from 40 wt % to 70 wt % of a polymer blend composition consisting of:
(v) from 50 to 80 wt % of a metallocene-catalyzed alpha-olefin polyethylene and
(vi) from 20 to 50 wt % of a random polypropylene copolymer;
b) at least one flame retardant; c) at least one ultraviolet stabilizer; and d) at least one pigment.

26 . The method of claim 25 , wherein the roofing membrane is produced by a combination of twin screw extensions as the physical blending followed by a calendaring process.

27 . The method of claim 26 , wherein the components are directly fed into an extruder such that melting, mixing, and extrusion occurs simultaneously, and then calendaring extruded material.

28 . The process of claim 27 , wherein the calendared extruded material is wound into a roll.

Assignees

• Johns Manville

Inventors

• Pedrazzoli Diego
• Peng Lichih R
• Shen Changqing
• Wang Lance
• Asrar Jawed

Classifications

• C08L2207/066

  LDPE (radical process) · CPC title

• C08L2205/02

  containing two or more polymers of the same C08L -group · CPC title

• C08K2003/265

  Calcium, strontium or barium carbonate · CPC title

• C08K2003/2241

  Titanium dioxide · CPC title

• E04D5/06 Primary

  by making use of plastics · CPC title