WO2008094603A1

WO2008094603A1 - Polymeric laminates including nano-particulates

Info

Publication number: WO2008094603A1
Application number: PCT/US2008/001232
Authority: WO
Inventors: Richard Peng
Original assignee: Firestone Building Products Company, Llc
Priority date: 2007-01-30
Filing date: 2008-01-30
Publication date: 2008-08-07

Abstract

Polymeric laminates including at least one layer that includes inorganic nano-particulates.

Description

POLYMERIC LAMINATES INCLUDING NANO-PARTICULATES [0001] This application claims the benefit of U.S. Provisional Application No. 60/898,349, filed January 30, 2007, which is incorporated herein by reference.

FIELD OF THE INVENTION

[0002] One or more embodiments of the present invention are directed toward polymeric laminates including at least one layer that includes inorganic nano-particulates.

BACKGROUND OF THE INVENTION [0003] Many roofs, especially flat or low-sloped roofs, are covered with a polymeric membrane. Polymeric membranes used in these applications include both thermoset membranes and thermoplastic membranes. Exemplary thermoset membranes include EPDM rubber. Thermoplastic membranes include PVC membranes and olefinic-based thermoplastic membranes. [0004] Mineral fillers may be employed to provide a polymeric membrane that is white or off-white. Mineral-filled membranes may exhibit improved sunlight reflectance and improved burn resistance, when compared to carbon-black reinforced membranes. Certain inorganic metal oxides may be employed to provide antibacterial and/or antifungal properties. However, the use of large amounts of mineral fillers or other additives can have some drawbacks including cost and loss of mechanical properties.

SUMMARY OF THE INVENTION

[0005] One or more of embodiments of the present invention provide a flexible polymeric laminate comprising a first layer including a thermoplastic resin having inorganic nano-particulates dispersed therein, and a second layer, compositionally distinct from the first layer, where the second layer includes less than about 1 % by weight inorganic nano-particulates.

[0006] One or more embodiments of the present invention further provide a roof comprising a roof deck, and a flexible membrane, where said flexible laminate includes inorganic nano-particulates. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Fig. 1 is a perspective, cross-sectional view of a membrane according to one or more embodiments of the present invention; [0008] Fig. 2 is a perspective, cross-sectional view of a membrane according to one or more embodiments of the present invention;

[0009] Fig. 3 is a perspective, cross-sectional view of a built-up roof including a roofing membrane according to one or more embodiments of the present invention.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS [0010] One or more embodiments of the present invention are directed toward flexible polymeric laminates, which may also be referred to as laminate membranes or simply membranes. These membranes may include multi-layered membranes that include at least two polymeric layers (i.e. two layers including polymeric material). The polymeric layers may also be referred to as polymeric sheets. Polymeric layers include a continuous polymeric phase where the polymeric phase is generally compositionally similar throughout the layer. The polymeric layer may also include non-polymeric constituents such as fillers or other additives. The membranes of the present invention may also include other constituents that are not polymeric layers. For example, the membranes may include reinforcing scrims or fabric.

[0011] As shown in Fig. 1, one embodiment of the laminate membrane 10 includes first layer 12 and second layer 14. In one or more embodiments, first layer 12, which may be referred to as cap layer 12, includes inorganic nano- particulates; as a result, first layer 12 may also be referred to as inorganic nano- particulate layer 12. Layers 12 and 14 of membrane 10 are not necessarily drawn to scale. As will be discussed herein, in one or more embodiments, first layer 12 may be thinner than second layer 14. Also, in certain embodiments, second layer 14 may include several sublayers, or membrane 10 may include additional layers not shown in Fig. 1. [0012] First layer 12 and second layer 14 are adjacent to one another and contact each other along an interfacing planar surface 16. In certain embodiments, first layer 12 and second layer 14 may be laminated (e.g. heat laminated). In one or more embodiments, first layer 12 and second layer 14 are integral (e.g. heat laminated) along planar surface as a result of being co-extruded with one another. The co-extrusion of layered material is further described in International Patent Application No. PCT/US06/33522, which is incorporated by reference. [0013] The membranes of one or more embodiments of the present invention are useful as protective membranes, particularly water resistant membranes, on roofs.

[0014] In one or more embodiments, first layer 12 and second layer 14 are compositionally distinct. In one or more embodiments, the layers are compositionally distinct based upon the presence, or lack thereof, of a threshold amount of inorganic nano-particulates.

[0015] The inorganic nano-particulates, which may for purposes of this specification be simply referred to as nano-particulates, may include metal oxides, metal carbonates, metal sulfides, metal salts, and metal borates, and may be characterized by having a particle size in at least one dimension in the nano-range. In one or more embodiments, the nano-particulates include zinc oxide, tin oxide, copper oxide, zinc carbonate, tin carbonate, copper carbonate, zinc sulfide, tin sulfide, copper sulfide, zinc chloride, tin chloride, copper chloride, zinc borate, tin borate, or copper borate, or mixtures thereof. In one or more embodiments, nano- particulates disclosed in U.S. Pat. Nos. 6,699,316 and/or 6,884,501, which are incorporated herein by reference, may be employed.

[0016] In one or more embodiments, the nano-particulates may be exfoliated or otherwise treated to produce layered materials having a thickness of about 400 nanometers in at least one direction. In other embodiments, the exfoliated layered materials have a thickness of about 300 nanometers in at least one direction, in yet other embodiments about 200 nanometers, it still other embodiments about 100 nanometers, and in yet other embodiments about 50 nanometers in at least one direction.

[0017] In other words, in one or more embodiments, the nano-particulates are characterized by having a particle size in at least one dimension in the nano-range as dispersed within first layer 12. For example, first layer 12 may include nano- particulates dispersed therein having at least one dimension of less than about 400 nanometers, in other embodiments less than about 300 nanometers, in other embodiments less than about 200 nanometers, in other embodiments less than about 100 nanometers, and in other embodiments less than about 50 nanometers. [0018] In one or more embodiments, the nano-particulates, as introduced to the composition employed to form first layer 12, may be larger in one or more dimensions, including all dimensions, than 400 nanometers, or larger than the nano-scale. These metaloxides, however, may be treated so that upon introduction and dispersion into a composition (e.g. polymer) they will exfoliate to produce layered material having at least one dimension in the nano-range as noted above. In other embodiments, the nano-particulates are introduced to the composition for forming layer 12 in an exfoliated state (e.g. having at least one dimension in the nano-scale) as part of a masterbatch with at least one other component. For example, a polymeric masterbatch of at least one polymer and the nano- particulates may be introduced into a composition for forming first layer 12. In any event, those skilled in the art understand that nano-particulates may include layered materials that, upon de-layering or de-agglomeration of the individual layers, produce particles having at least one dimension in the nano-range. [0019] In one or more embodiments, first layer 12 includes a thermoplastic polymer or a blend of thermoplastic polymers. In one or more embodiments, thermoplastic polymers include those polymers that are melt processable by employing one or more standard melt processing techniques such as melt extruding. In one embodiment, first layer 12 includes linear low density polyethylene.

[0020] In one or more embodiments, the thermoplastic polymers may be characterized by a melting point. In one or more embodiments, the thermoplastic polymer may have a melting point greater than 120⁰C, and in other embodiments greater than 130°C.

[0021] In one or more embodiments, the thermoplastic polymer may be characterized by a melting point greater than 120⁰C and in other embodiments greater than 130⁰C. In one or more embodiments, the thermoplastic polymer may be characterized by a crystallinity that is greater than 1%, in other embodiments greater than 10%, in other embodiments greater than 20%, in other embodiments greater than 30%, an in other embodiments greater than 40%. [0022] In one or more embodiments, the thermoplastic polymer employed in one more layers of the laminates of the present invention may include a blend of olefinic polymers. Useful blends include those described in International Application No. PCT/US06/033522 which is incorporated herein by reference. For example, a particular blend may include (i) a plastomer, (ii) a low density polyethylene, and (iii) a propylene-based polymer.

[0023] In one or more embodiments, the thermoplastic polymer includes a propylene-based copolymer, a low density polyethylene, and a plastomer. Propylene-based copolymers may include polypropylene homopolymer or copolymers of propylene and a comonomer, where the copolymer includes, on a mole basis, a majority of mer units deriving from propylene. In one or more embodiments, the propylene-based copolymers may include from about 2 to about 6 mole percent, and in other embodiments from about 3 to about 5 mole percent mer units deriving from the comonomer with the remainder including mer units deriving from propylene. In one or more embodiments, the comonomer includes at least one of ethylene and an α-olefin. The α-olefins may include butene-1, pentene-1, hexene-1, oxtene-1, or 4-methyl-pentene-l. In one or more embodiments, the copolymers of propylene and a comonomer may include random copolymers. Random copolymers may include those propylene-based copolymers where the comonomer is randomly distributed across the polymer backbone.

[0024] The propylene-based polymers employed in one or more embodiments of this invention may be characterized by a melt flow rate of from about 0.5 to about 15 dg/min, in other embodiments from about 0.7 to about 12 dg/min, and in other embodiments from about 1 to about 10 dg/min per ASTM D- 1238 at 230⁰C and 2.16 kg load. In these or other embodiments, the propylene- based polymers may have a weight average molecular weight (Mw) of from about 1 x 105 to about 5 x 105 g/mole, in other embodiments from about 2 x 105 to about 4 x 105 g/mole, and in other embodiments from about 3 x 105 to about 4 x 105 g/mole, as measured by GPC with polystyrene standards. The molecular weight distribution of the propylene-based copolymer may be from about 2.5 to about 4, in other embodiments from about 2.7 to about 3.5, and in other embodiments from about 2.8 to about 3.2. [0025] In one or more embodiments, propylene-based polymers may be characterized by a melt temperature (Tm) that is from about 165°C to about 130⁰C, in other embodiments from about 160 to about 140⁰C, and in other embodiments from about 155°C to about 140⁰C. In one or more embodiments, particularly where the propylene-based polymer is a copolymer of propylene and a comonomer, the melt temperature may be below 16O⁰C, in other embodiments below 155°C, in other embodiments below 150⁰C, and in other embodiments below 145°C. In one or more embodiments, they may have a crystallization temperature (Tc) of about at least 9O⁰C, in other embodiments at least about 95°C, and in other embodiments at least 100⁰C, with one embodiment ranging from 105° to 115°C.

[0026] Also, these propylene-based polymers may be characterized by having a heat of fusion of at least 25 J/g, in other embodiments in excess of 50 J/g, in other embodiments in excess of 100 J/g, and in other embodiments in excess of 140 J/g.

[0027] In one or more embodiments, the propylene-based polymers may be characterized by a flexural modulus, which may also be referred to as a 1% secant modulus, in excess of 120,000 psi, in other embodiments in excess of 125,000, in other embodiments in excess of 130,000 psi, in other embodiments in excess of 133,000 psi, in other embodiments in excess of 135,000 psi, and in other embodiments in excess of 137,000 psi, as measured according to ASTM D-790. [0028] Useful propylene-based polymers include those that are commercially available. For example, propylene-based polymers can be obtained under the tradename PP7620Z™ (Fina); or under the tradename TR3020™ (Sunoco).

[0029] In one or more embodiments, the low density polyethylene includes an ethylene-α-olefin copolymer. In one or more embodiments, the low density polyethylene includes linear low density polyethylene. The linear low density polyethylene employed in one or more embodiments of this invention may be similar to that described in U.S. Patent No. 5,266,392, which is incorporated herein by reference. This copolymer may include from about 2.5 to about 13 mole percent, and in other embodiments from about 3.5 to about 10 mole percent, mer units deriving from α-olefins, with the balance including mer units deriving from ethylene. The α-olefin included in the linear low density polyethylene of one or more embodiments of this invention may include butene-1, pentene-1, hexene-1, octene-1, or 4-methyl-pentene-l. In one or more embodiments, the linear low density polyethylene is devoid or substantially devoid of propylene mer units (i.e., units deriving from propylene). Substantially devoid refers to that amount or less propylene mer units that would otherwise have an appreciable impact on the copolymer or the compositions of this invention. [0030] In one embodiment, the linear low density polyethylene may be characterized by a density of from about 0.885 g/cc to about 0.930 g/cc, in other embodiments from about 0.900 g/cc to about 0.920 g/cc, and in other embodiments from about 0.900 g/cc to about 0.910 g/cc per ASTM D-792. [0031] In one or more embodiments, the linear low density polyethylene may be characterized by a weight average molecular weight of from about 1 x 105 to about 5 x 105 g/mole, in other embodiments 2 x 105 to about 10 x 105 g/mole, in other embodiments from about 5 x 105 to about 8 x 105 g/mole, and in other embodiments from about 6 x 105 to about 7 x 105 g/mole as measured by GPC with polystyrene standards. In these or other embodiments, the linear low density polyethylene may be characterized by a molecular weight distribution (Mw/Mn) of from about 2.5 to about 25, in other embodiments from about 3 to about 20, and in other embodiments from about 3.5 to about 10. In these or other embodiments, the linear low density polyethylene may be characterized by a melt flow rate of from about 0.2 to about 10 dg/min, in other embodiments from about 0.4 to about 5 dg/min, and in other embodiments from about 0.6 to about 2 dg/min per ASTM D-1238 at 230⁰C and 2.16 kg load.

[0032] In one or more embodiments, the linear low density polyethylene may be prepared by using a convention Ziegler Natta coordination catalyst system. [0033] Useful linear low density polyethylene includes those that are commercially available. For example, linear low density polyethylene can be obtained under the tradename Dowlex™ 2267G (Dow); or under the tradename DFDA-1010 NT7 (Dow). [0034] In one or more embodiments, plastomers include an ethylene-α- olefin copolymer, such as those described in U.S. Patent Nos. 6,207,754, 6,506,842, 5,226,392, and 5,747,592, which are incorporated herein by reference. Plastomers may include from about 1.0 to about 15 mole percent, in other embodiments from about 2 to about 12, and in other embodiments from about 3 to about 9 mole percent and in other embodiments from about 3.5 to about 8 mole percent, mer units deriving from α-olefins, with the balance including mer units deriving from ethylene. The α-olefin may include butene-1, pentene-1, hexene-1, octene-1, or 4-methyl-pentene-l. [0035] In one or more embodiments, plastomers may be characterized by a density of from about 0.865 g/cc to about 0.900 g/cc, in other embodiments from about 0.870 to about 0.890 g/cc, and in other embodiments from about 0.875 to about 0.880 g/cc per ASTM D-792. In these or other embodiments, the density of the plastomers may be less than 0.900 g/cc, in other embodiments less than 0.890 g/cc, in other embodiments less than 0.880 g/cc, and in other embodiments less than 0.875 g/cc.

[0036] In one or more embodiments, the plastomer may be characterized by a weight average molecular weight of from about 7 x 104 to 13 x 104 g/mole, in other embodiments from about 8 x 104 to about 12 x 104 g/mole, and in other embodiments from about 9 x 104 to about H x 104 g/mole as measured by using GPC with polystyrene standards. In these or other embodiments, the plastomer may be characterized by a weight average molecular weight in excess of 5 x 104 g/mole, in other embodiments in excess of 6 x 104 g/mole, in other embodiments in excess of 7 x 104 g/mole, and in other embodiments in excess of 9 x 104 g/mole. In these or other embodiments, the plastomer may be characterized by a molecular weight distribution (Mw/Mn) that is from about 1.5 to 2.8, in other embodiments 1.7 to 2.4, and in other embodiments 2 to 2.3. [0037] In these or other embodiments, the plastomer may be characterized by a melt index of from about 0.1 to about 8, in other embodiments from about 0.3 to about 7, and in other embodiments from about 0.5 to about 5 per ASTM D-1238 at 190⁰C and 2.16 kg load. [0038] The uniformity of the comonomer distribution of the plastomer of one or more embodiments, when expressed as a comonomer distribution breadth index value (CDBI), provides for a CDBI of greater than 60, in other embodiments greater than 80, and in other embodiments greater than 90. [0039] In one or more embodiments, the plastomer may be characterized by a DSC melting point curve that exhibits the occurrence of a single melting point break occurring in the region of 50 to 110⁰C.

[0040] In one or more embodiments, the plastomer may be prepared by using a single-site coordination catalyst including metallocene catalyst, which are conventionally known in the art.

[0041] Useful plastomer includes those that are commercially available.

For example, plastomer can be obtained under the tradename EXXACT ™ 8201 (ExxonMobil); or under the tradename ENGAGE™ 8180 (Dow DuPont). [0042] In one or more embodiments, the thermoplastic polymer may include a reactor copolymer. Reactor copolymers are generally known in the art and may include those blends of olefinic polymers that result from the polymerization of ethylene and α-olefins with sundry catalyst systems. In one or more embodiments, these blends are made by in-reactor sequential polymerization. Reactor copolymers useful in one or more embodiments include those disclosed in U.S. Patent No. 6,451,897, which is incorporated therein by reference.

[0043] In one or more embodiments, the thermoplastic polymer may include a functionalized thermoplastic polymer. Functionalized thermoplastic polymers may include from about 1.0 to about 7, in other embodiments from about 2 to about 6, and in other embodiments form about 3 to about 5 mole % mer units that include a functional group. The functional group, which may include a pendant moiety, may include an acid or anhydride group. These acid or anhydride groups may derive from unsaturated carboxylic acids or unsaturated anhydrides. Examples of unsaturated carboxylic acids include citraconic acid, cinnamic acid, methacrylic acid, and itaconic acid. Examples of unsaturated anhydrides include maleic anhydride, citraconic anhydride, and itaconic anhydride. The resin can be functionalized by copolymerizing unsaturated carboxylic acids or unsaturated anhydrides together with other monomer to form the polymer backbone, or the unsaturated carboxylic acids or unsaturated anhydrides can be subsequently grafted to the polymer backbone.

[0044] Functionalized low density polyethylene resins are commercially available. For example, they can be obtained under the commercial name FUSABOND™ MB 226D (DuPont), or KRAYTON™ FG 1901X.

[0045] In one or more embodiments, first layer 12 includes one or more additional components selected from flame retardants, clay, processing aids, and rubber.

[0046] Flame retardants may include any compound that will increase the burn resistivity of the polymeric sheets of the present invention. In one or more embodiments, this includes resistance to flame spread as tested by UL94 and/or UL790. In one or more embodiments, useful flame retardants include those that operate by forming a char-layer across the surface of a specimen when exposed to a flame. Other flame retardants include those that operate by releasing water upon thermal decomposition of the flame retardant compound. Useful flame retardants may also be categorized as halogenated flame retardants or non- halogenated flame retardants. In one or more embodiments, mixtures of these flame retardants may be employed. [0047] Exemplary non-halogenated flame retardants include magnesium hydroxide, aluminum trihydrate, zinc borate, ammonium polyphosphate, melamine polyphosphate, and antimony oxide (Sb2θ3). Magnesium hydroxide

(Mg(OH)2) is commercially available under the tradename Vertex™ 60, ammonium polyphosphate is commercially available under the tradename

Exolite™ AP 760 (Clarian), which is sold together as a polyol masterbatch, melamine polyphosphate is available under the tradename Budit™ 3141

(Budenheim), and antimony oxide (Sb2θ3) is commercially available under the tradename Fireshield™. Those flame retardants from the foregoing list that are believed to operate by forming a char layer include ammonium polyphosphate and melamine polyphosphate. [0048] In one or more embodiments, treated or functionalized magnesium hydroxide may be employed. For example, magnesium oxide treated with or reacted with a carboxylic acid or anhydride may be employed. In one embodiment, the magnesium hydroxide may be treated or reacted with stearic acid. In other embodiments, the magnesium hydroxide may be treated with or reacted with certain silicon-containing compounds. The silicon-containing compounds may include silanes, polysiloxanes including silane reactive groups. In other embodiments, the magnesium hydroxide may be treated with maleic anhydride. Treated magnesium hydroxide is commercially available. For example, Zerogen™ 50.

[0049] Examples of halogenated flame retardants may include halogenated organic species or hydrocarbons such as hexabromocyclododecane or N,N'- ethylene-bis-(tetrabromophthalimide). Hexabromocyclododecane is commercially available under the tradename CD-75P™ (ChemTura). N,N'-ethylene-bis- (tetrabromophthalimide) is commercially available under the tradename Saytex™ BT-93 (Albemarle). [0050] In one or more embodiments, the use of char-forming flame retardants (e.g. ammonium polyphosphate and melamine polyphosphate) has unexpectedly shown advantageous results when used in conjunction with nano-particulate within the cap layer of the laminates of the present invention. It is believed that there may be a synergistic effect when these compounds are present in the cap layer. As a result, the cap layer of the laminates of the certain embodiments of the present invention are devoid of or substantially devoid of halogenated flame retardants and/or flame retardants that release water upon thermal decomposition. Substantially devoid referring to that amount or less that does not have an appreciable impact on the laminates, the cap layer, and/or the burn resistivity of the laminates. [0051] In one or more embodiments, the layer or polymeric sheet including nano-particulates (e.g. layer 12) may also include a nanoclay. As is understood by those skilled in the art, nanoclays are distinct from nano- particulates. Nanoclays include the smectite clays, which may also be referred to as layered silicate minerals. In one or more embodiments, these clays include exchangeable cations that can be treated with organic swelling agents such as organic ammonium ions, to intercalate the organic molecules between adjacent planar silicate layers, thereby substantially increasing the interlayer spacing. The expansion of the interlayer distance of the layered silicate can facilitate the intercalation of the clay with other materials. The interlayer spacing of the silicates can be further increased by formation of the polymerized monomer chains between the silicate layers. The intercalated silicate platelets act as a nanoscale (sub-micron size) filler for the polymer.

[0052] Intercalation of the silicate layers in the clay can take place either by cation exchange or by absorption. For intercalation by absorption, dipolar functional organic molecules such as nitrile, carboxylic acid, hydroxy, and pyrrolidone groups are desirably present on the clay surface. Intercalation by absorption can take place when either acid or non-acid clays are used as the starting material. Cation exchange can take place if an ionic clay containing ions such as, for example, Na+, K+, Ca+ +, Ba+ +, and Li+ is used. Ionic clays can also absorb dipolar organic molecules. [0053] Smectite clays include, for example, montmorillonite, saponite, beidellite, hectorite, and stevensite. In one or more embodiments, the space between silicate layers may be from about 15 to about 40 A, and in other embodiments from about 17 to about 36 A, as measured by small angle X-ray scattering. Typically, a clay with exchangeable cations such as sodium, calcium and lithium ions may be used. Montmorillonite in the sodium exchanged form is employed in one or more embodiments.

[0054] Organic swelling agents that can be used to treat the clay include quaternary ammonium compound, excluding pyridinium ion, such as, for example, poly (propylene glycol)bis(2-aminopropyl ether), poly(vinylpyrrolidone), dodecylamine hydrochloride, octadecylamine hydrochloride, and dodecylpyrrolidone. These treated clays are commercially available. One or more of these swelling agents can be used.

[0055] Polymeric laminates containing nanoclays are further described in

International Application PCT/US2007/011922, which is incorporated herein by reference. [0056] In one or more embodiments, one or more layers of the laminates of the present invention may include a processing aid. Processing aids include those compounds that can be added to the thermoplastic polymer composition to assist in processing or extend the polymeric materials. In one or more embodiments, processing aids include those compounds that can reduce the viscosity and/or increase the flow of the thermoplastic polymer. Exemplary processing aids include metal salts of carboxylic acids including metal salts of naturally occurring fats and oils. In one or more embodiments, processing aids include calcium stearate and/or zinc stearate. In other embodiments, processing aids include processing oils such as those that are conventional in plastics and/or rubber processing. [0057] In one or more embodiments, layer 12 also includes a rubber.

Rubbers include those polymers characterized by a crystallinity of less than 1%, in other embodiments less than 0.5%, and in other embodiments less than 0.1%. Exemplary rubbers include polymers of conjugated dienes, ethylene-propylene rubber, ethylene-propylene-diene rubber, butyl rubber, nitrile rubber, and mixtures thereof. In certain embodiments, the rubber includes those polymers that do not have a melting point. [0058] In one or more embodiments, one or more layers of the laminates layer include a stabilizers. Stabilizers may include one or more of a UV stabilizer, an antioxidant, and an antiozonant. UV stabilizers include Tinuvin™ 622. Antioxidants include Irganox™ 1010. [0059] In addition to the foregoing, one or more layers may also include other ingredients or constituents that are commonly included in polymeric compounds. These ingredients may include pigment such as Tiθ2- In certain embodiments, especially where the membrane is employed as a geomembrane, carbon black may be employed as a pigment or reinforcement.

[0060] In one or more embodiments, first layer 12, and in these or other embodiments layers 12 and 14, include sufficient thermoplastic polymer and/or thermoplastic polymer arranged in the appropriate morphology to render the one or more layers melt processable by employing one or more standard melt processing techniques such as melt extruding.

[0061] In one or more embodiments, the one or more layers of the laminates may include from about 5 to about 50% by weight, in other embodiments from about 10 to about 45% by weight, and in other embodiments from about 15 to about 38% by weight plastomer, based upon the total weight of the polymeric component of the polymeric layer, where the polymeric component refers to all polymeric constituents of the layer, (e.g., plastomer, low density polyethylene, and propylene-based polymer). In these or other embodiments, one or more layers may include at least 5% by weight, in other embodiments at least 10% by weight, and in other embodiments at least 15% by weight plastomer, based upon the total weight of the polymeric component of the polymeric layer; in these or other embodiments, one or more layers may include less than 50% by weight, in other embodiments less than 45% by weight, and in other embodiments less than 38% by weight plastomer based upon the total weight of the polymeric component of the polymeric layer. In one or more embodiments, one or more layers of the membranes of this invention include sufficient plastomer so as to be flexible at - 40⁰C. In one or more embodiments, one or more layers includes sufficient plastomer so as to pass the brittle-point test of ASTM D-2137. [0062] In one or more embodiments, one or more layers of the laminates of this invention may include from about 10 to about 90% by weight, in other embodiments from about 15 to about 85% by weight, and in other embodiments from about 25 to about 75% by weight low density polyethylene, based upon the total weight of the polymeric component of the polymeric layer. In these or other embodiments, one or more layers may include at least 31% by weight, in other embodiments at least 33% by weight, in other embodiments at least 35% by weight, and in other embodiments at least 40% by weight low density polyethylene (e.g., linear low density polyethylene), based upon the total weight of the polymeric component of the polymeric layer; in these or other embodiments, one or more layers may include less than 90%. by weight, and in other embodiments less than 75% by weight low density polyethylene based upon the total weight of the polymeric component of the polymeric layer. In one or more embodiments, one or more layers of the membranes of this invention include sufficient low density polyethylene so as to provide high tensile and tear. In one or more embodiments, the layer includes sufficient low density polyethylene to provide elongation of at least 500% (ASTM D-412) and a Die-C tear of at least 525 newtons/cm per ASTM D-624. [0063] In one or more embodiments, one or more layers of the laminates this invention may include from about 5 to about 50% by weight, in other embodiments from about 10 to about 45% by weight, and in other embodiments from about 15 to about 35% by weight propylene-based polymer, based upon the total weight of the polymeric component of the polymeric layer. In these or other embodiments, one or more layers may include at least 5% by weight, in other embodiments at least 10% by weight, and in other embodiments at least 15% by weight propylene-based polymer, based upon the total weight of the polymeric component of the polymeric layer; in these or other embodiments, one or more layers may include less than 50%, in other embodiments less than 49% by weight, and in other embodiments less than 45% by weight propylene-based polymer based upon the total weight of the polymeric component of the polymeric layer. In one or more embodiments, one or more layers of the membranes of this invention include sufficient propylene polymer so as to withstand 116°C aging for 7 days, where membranes or layers that do not withstand these conditions will flow or deform. In one or embodiments, the cap layer of the laminates of the present invention includes sufficient nanoclay to improve the flame resistance (UL 790 and/or UL 94), oil resistance (ASTM 876 and UL-1581), oxygen permeability, long-term weathering, and/or water permeability (ASTM E96-B) of the laminates. [0064] In one or more embodiments, the layer including the nano- particulates such as first layer 12 (e.g. cap layer), includes at least about 0.5 weight percent (% by weight), in other embodiments at least about 0.8 weight percent, in other embodiments at least about 1 weight percent, in other embodiments at least about 1.5 weight percent, and in other embodiments at least about 2.5 weight percent inorganic nano-particulates, based upon the total weight of the layer (e.g. cap layer). In these or other embodiments, first layer 12 includes less than 10 weight percent, in other embodiments less than 8 weight percent, and in other embodiments less than 5 weight percent inorganic nano-particulates, based on the total weight of the cap layer. In one or more embodiments, the cap layer includes from about 0.5 to about 10 weight percent, in other embodiments from about 0.8 to about 5 weight percent, and in other embodiments from about 1 to about 3 weight percent nano-particulates, based upon the total weight of the cap layer. [0065] In one or more embodiments, layer 12, and in certain embodiments both layers 12 and 14, include sufficient flame retardants so that, when combined with the nano-particulates, the membranes pass industry standards for flame spread and/or flammability. In one or more embodiments, one or more of the layers include sufficient flame retardant that when combined with the nano-particulates allow the membrane to pass the flame spread test of UL- 790. [0066] In one or more embodiments, the use of the nano-particulate may allow for the use of less flame retardant than would otherwise be required to meet industry standards. In one or more embodiments, cap layer 12 includes less than 80%, in other embodiments less than 70%, in other embodiments less than 60%, and in other embodiments less than 50%, and in other embodiments from about 30 to about 70% of an amount of flame retardant that would otherwise, be required to meet UL- 790 in the absence of the nano-particulate. [0067] In certain embodiments, the cap layer includes from about 5 to about 50 weight percent, in other embodiments from about 10 to about 40 weight percent, and in other embodiments from about 15 to about 30 weight percent non- halogenated flame retardant, based upon the total weight of the cap layer. [0068] In one or more embodiments, the cap layer includes from about 3 to about 30 weight percent, in other embodiments from about 5 to about 25 weight percent, and in other embodiments from about 10 to about 20 weight percent halogenated flame retardant based upon the total weight of the cap layer. [0069] In one or embodiments, one or more layers of the membranes of the present invention includes sufficient nano-particulate to improve the flame resistance, oil resistance (ASTM 876 and UL- 1581), oxygen permeability, long- term weathering, and/or water permeability (ASTM E96-B) of the membrane.

[0070] The membranes of one or more embodiments of the present invention advantageously meet many of the standards that are currently met by PVC membranes. [0071] In one or more embodiments, cap layer 12 includes less than 1.0 weight percent, in other embodiments less than 0.5 weight percent, in other embodiments less than 0.2 weight percent, in other embodiments less than 0.1 weight percent, and in other embodiments at less than 0.05 weight percent processing aids, based upon the total weight of the cap layer. In one or more embodiments, cap layer 12, and in other embodiments both layers 12 and 14 are substantially devoid of processing aids, where substantially devoid refers to an amount less than that amount that would otherwise have an appreciable impact on the membrane or its processing period. In one or more embodiments, layer 12 and/or layer 14 are devoid of processing aids.

[0072] In one or more embodiments, first layer 12, and in these or other embodiments both layers 12 and 14, may include from about 0.5 to about 20% by weight, in other embodiments from about 1 to about 10% by weight, and in other embodiments from about 2 to about 5% by weight rubber, based on the total weight of the layer.

[0073] In one or more embodiments, first layer 12, and in these or other embodiments both layers 12 and 14, include less than 2 percent by weight, in other embodiments less than 1 percent by weight, in other embodiments less than 0.5 percent by weight, and in other embodiments less than 0.1 percent by weight rubber. In one or more embodiments, the layers are substantially devoid of rubber, where substantially devoid refers to less than that amount of rubber that would otherwise have an appreciable impact on the layer. In certain embodiments, one or more layers are devoid of rubber. [0074] In or more embodiments, the cap layer 12 is characterized by a torsional stiffness, as determined by ASTM D4065 using a Rheometric Dynamic Analyzer, of at least 3.5 x 109, in other embodiments at least 4.0 x 109, in other embodiments at least 4.5 x 109, and in other embodiments from about 2.5 x 109 to about 6.0 x 109 dynes/cm2. [0075] In or more embodiments, cap layer 12 is characterized by a melt temperature of from about 110⁰C to about 170⁰C, in other embodiments from about 120⁰C to about 160°, and in other embodiments from about 130⁰C to about 150⁰C.

[0076] In one or more embodiments, cap layer 12 has a thickness of less than 30 mil (0.76 mm), in other embodiments less than 25 mil (0.64 mm), in other embodiments less than 20 mil (0.51 mm) and in other embodiments less than 15 mil (0.38 mm); in these or other embodiments, the cap layer has a thickness of at least 4 mil (0.1 mm), in other embodiments at least 6 mil (0.15 mm), and in other embodiments at least 10 mil (0.3 mm).

[0077] In one or more embodiments, second layer 14 may include similar constituents and have similar characteristics as first layer 12, described hereinabove. In one or more embodiments, second layer 14 is compositionally distinct from first layer 12 based upon the amount of inorganic nano-particulates. [0078] In one or more embodiments, the flexible polymeric laminate of the present invention concentrates the inorganic nano-particulates into the cap layer 12, and therefore less particulates are required on an overall basis. In one or more embodiments, second layer 14 includes less than about 1 weight percent, in other embodiments less than 0.5 weight percent, in other embodiments less than 0.1 weight percent, and in other embodiments less than 0.05 weight percent inorganic nano-particulates. In certain embodiments, layer 14 is substantially devoid of inorganic nano-particulates, which refers to an amount less than that amount that would have an appreciable impact on the layer or the membrane. In certain embodiments, layer 14 is devoid of inorganic nano-particulates. [0079] The fact that the laminates of the present invention may include compositionally distinct layers offers a number of advantages. For example, in certain embodiments less expensive polymers can be employed within inner layers 20 and 22. In certain embodiments, inner layers 20 and 22 may include low density polyethylene such as linear low density polyethylene as described hereinabove. Also, inner layers 20 and 22 may be devoid or substantially devoid of flame retardants and/or devoid or substantially devoid of nano-particulates. [0080] In one or more embodiments, membranes according to the present invention are multi-layer membranes that include three or more layers, and in certain embodiments include a four-layer polymeric membrane. An exemplary four-layer polymeric membrane is shown in Fig. 2. Here, membrane 10' includes skim layer 12' (also referred to as cap layer 12') polymeric sub-layers 14', which include first inner-liner layer 20, second inner-liner layer 22, and base layer 24. Also shown is optional reinforcement layer 30. In certain embodiments, reinforcement layer 30 can be positioned between second inner-liner layer 22 and base layer 24. In other embodiments, reinforcement layer 30 may not be present. In these or other embodiments, a reinforcing fleece may be secured to the underside 28 of base layer 24.

[0081] Cap layer 12' may include those constituents described above with respect to first layer 12 and include similar characteristics. [0082] Polymeric layers 14' may include similar constituents and have similar characteristics as second layer 14 described hereinabove. In certain embodiments, inner-liner layers 20 and 22 may include polymers that are compositionally distinct from those polymers employed in skim layer 12'. This is particularly advantageous inasmuch as less expensive polymers can be employed within inner layers 20 and 22. In certain embodiments, inner layers 20 and 22 may include low density polyethylene such as linear low density polyethylene as described hereinabove. Also, inner layers 20 and 22 may be devoid or substantially devoid of flame retardants and/or devoid or substantially devoid of inorganic nano-particulates. [0083] In certain embodiments, base layer 24 may include similar polymeric constituents to skim layer 12'. In certain embodiments, base layer 24, may likewise include nano-particulates in a similar fashion to skim layer 12'. In other embodiments, base layer 24 and skim layer 12' may be compositionally distinct based on the presence or absence of nano-particulates. [0084] Inasmuch as skim layer 12' includes nano-particulates, the presence of inner-liner layers 20 and 22 adjacent to reinforcement layer 30 provides a particular advantage. Inasmuch as skim layer 12' includes nano- particulates, the stiffness of skim layer 12', as may be determined by Torsional modulus or flexural modulus, may be increased. Inasmuch as inner-liner layers 20 and 22 do not include nano-particulates, or are substantially devoid of nano- particulates as described hereinabove, the stiffness of these layers, which are adjacent to reinforcement layer 30, is lower than that of skim layer 12' thereby having an advantageous impact on the overall mechanical properties of the membrane. [0085] In one or more embodiments, the reinforcement may include a woven or non-woven scrim or fabric. Included are those reinforcements conventionally employed in the art of making roofing membranes as disclosed in U.S. Serial Nos. 60/712,070 and 60/774,349, as well as, International Patent Application No. PCT/US06/33522, which are incorporated herein by reference. [0086] The thickness of the overall four-layered polymeric membrane as exemplified in Fig. 2 may be from about 20 to about 100 mil (0.51- 2.5 mm), in other embodiments from about 40 to about 90 mil (1.0- 2.3 mm), and in other embodiments from about 45 to about 85 mil (1.1- 2.2 mm). In certain embodiments the overall membrane has a thickness of 45 mil (1.1 mm), 60 mil (1.5 mm), or 80 mil (2.0 mm). [0087] In one or more embodiments, the laminates of the present invention may be prepared by extruding a polymeric composition into a sheet. Multiple sheets may be extruded and joined to form a laminate. A membrane including a reinforcing layer may be prepared by extruding at least one sheet on and/or below a reinforcement (e.g., a scrim). In other embodiments, the polymeric layer may be prepared as separate sheets, and the sheets may then be calandered with the scrim sandwiched therebetween to form a laminate. In one or more embodiments, the membranes of the present invention are prepared by employing co-extrusion technology. Useful techniques include those described in co-pending U.S. Serial Nos. 11/708,898 and 11/708,903, which are incorporated herein by reference. [0088] Following extrusion, and after optionally joining one or more polymeric layers, or optionally joining one or more polymeric layer together with a reinforcement, the membrane may be fabricated to a desired thickness. This may be accomplished by passing the membrane through a set of squeeze rolls positioned at a desired thickness. The membrane may then be allowed to cool and/or rolled for shipment and/or storage.

[0089] The polymeric composition that may be extruded to form the polymeric sheet may include the ingredients or constituents described herein. For example, the thermoplastic polymer employed to make cap layer 12 or 12' may have nano-particulates dispersed therein. In specific embodiments, the polymeric composition may include plastomer, low density polyethylene, propylene polymer, nano-particulates and flame retardant. The ingredients may be mixed together by employing conventional polymer mixing equipment and techniques. In one or more embodiments, an extruder may be employed to mix the ingredients. For example, single-screw or twin-screw extruders may be employed. [0090] In one embodiment, each of the polymeric ingredients {e.g., plastomer, low density polyethylene, and propylene polymer) may be added to the extruder at the feed throat of the extruder. The filler and other ingredients (e.g., nano- particulates and flame retardant) that may be desirable may be added at the feed throat or within a subsequent stage or barrel of the extruder (e.g., downstream of the feed throat). This can be accomplished, for example, by using a side feeder. One or more of the polymeric ingredients may also be added downstream of the feed throat. This may include partial addition at the feed throat and partial addition downstream, or complete downstream addition of one or more polymeric ingredients.

[0091] In one or more embodiments, at least a portion of the nano-particulates and/or flame retardant (e.g., ammonium polyphosphate) is added downstream of the feed throat. For example, at least 50% by weight, in other embodiments at least 75% by weight, in other embodiments at least 95% by weight, and in other embodiments at least 100% by weight of the flame retardant is added downstream of the feed throat. [0092] In one or more embodiments, the nano-particulates and/or flame retardant (e.g., ammonium polyphosphate) may be added downstream of the feed throat together with a carrier. The carrier may include a polymer having a melt flow rate in excess of about 10, in other embodiments in excess of about 5, and in other embodiments in excess of about 2. In one or more embodiments, the carrier may advantageously include one or more of the polymeric ingredients of the polymeric sheet.

[0093] The membranes of one or more embodiments of the present invention are useful in a number of applications. In one embodiment, the membranes may be useful for roofing membranes that are useful for covering flat or low-sloped roofs. In other embodiments, the membranes may be useful as geomembranes. Geomembranes include those employed as pond liners, water dams, animal waste treatment liners, and pond covers. [0094] As described above, the membranes of one or more embodiments of the present invention may be employed as roofing membranes. These membranes include thermoplastic roofing membranes including those that meet the specifications of ASTM D-6878-03. These membranes maybe employed to cover flat or low/sloped roofs including built-up roofs. The membranes of the present invention are useful for covering roofs. In one or more embodiments, they can be used to create built-up roofs including flat and low-slope roofs. These roofs are generally known in the art as disclosed in U.S. Serial Nos. 60/586,424 and 11/343,466, and International Application No. PCT/US2005/024232, which are incorporated herein by reference. As shown in Fig. 3, a flat or low-sloped built-up roof 30 may include a roof deck 32, and optional insulation layer 34, and membrane 10.

[0095] Practice of this invention is not limited by the selection of any particular roof deck. Accordingly, the roofing systems herein can include a variety of roof decks. Exemplary roof decks include concrete pads, steel decks, wood beams, and foamed concrete decks.

[0096] Practice of this invention is likewise not limited by the selection of any particular insulation board. Moreover, the insulation boards are optional. Several insulation materials can be employed including polyurethane or polyisocyanurate cellular materials. These boards are known as described in U.S. Patent Nos. 6,117,375, 6,044,604, 5,891,563, 5,573,092, U.S. Publication Nos. 2004/01099832003/0082365, 2003/0153656, 2003/0032351, and

2002/0013379, as well as U.S. Serial Nos. 10/640,895, 10/925,654, and 10/632,343, which is incorporated herein by reference. [0097] In other embodiments, these membranes may be employed to cover flat or low-slope roofs following a re-roofing event. In one or more embodiments, the membranes may be employed for re-roofing as described in U.S. Publication No. 2006/0179749, which are incorporated herein by reference. [0098] The membranes of the present invention are useful for covering roofs. In one or more embodiments, they can be used to create built-up roofs including flat and low-slope roofs. These roofs are generally known in the art as disclosed in U.S. Serial Nos. 60/586,424 and 11/343,466, and International Application No. PCT/US2005/024232, which are incorporated herein by reference. [0099] In one or more embodiments, the inorganic nano-particulates provide mechanical reinforcement and flame resistance, such that the conventional amounts of flame retardant may be reduced.

[00100] In one or more embodiments, the flexible polymeric laminates of the present invention exhibit good oxygen barrier properties, such that the conventional amounts of antioxidants and UV stabilizers can be reduced. [00101] In one or more embodiments, the flexible polymeric laminates of the present invention contain lower amounts of the expensive hindered amine type UV stabilizers than required in conventional roofing membranes, yet still exhibit good resistance to UVA and UVB radiation.

[00102] In one or more embodiments, the flexible polymeric laminates of the present invention exhibit high reflectivity and good antibacterial and antifungal properties, such that high reflectivity is maintained over a substantial period of time. [00103] Various modifications and alterations that do not depart from the scope and spirit of this invention will become apparent to those skilled in the art. This invention is not to be duly limited to the illustrative embodiments set forth herein.

Claims

CLAIMSWhat is claimed is:

1. A flexible polymeric laminate comprising: a first layer including a thermoplastic resin having inorganic nano- particulates dispersed therein; and a second layer compositionally distinct from the first layer, where said second layer includes less than about 1% by weight inorganic nano- particulates.

2. The laminate of claim 1, where said second layer is substantially devoid of inorganic nano-particulates.

3. The laminate of claim 1, where said first layer has a thickness of less than about 30 mil.

4. The laminate of claim 1, where said first layer has a thickness of less than about 20 mil.

5. The laminate of claim 1, where said first layer has a thickness of at least about 10 mil.

6. The laminate of claim 1, where said flexible polymeric laminate has a thickness of from about 50 to about 90.

7. The laminate of claim 1, where said first layer includes at least about 0.5% by weight inorganic nano-particulates.

8. The laminate of claim 1, where said first layer includes at least about 0.8% by weight inorganic nano-particulates.

9. The laminate of claim 1, where said first layer includes from about 0.5 to about 10% by weight inorganic nano-particulates.

10. The laminate of claim 1, where said inorganic nano-particulates include a metal oxide, a metal carbonate, a metal sulfide, a metal salt, a metal borate, or a mixture thereof.

11. The laminate of claim 1, where said inorganic nano-particulates include zinc oxide, tin oxide, copper oxide, zinc carbonate, tin carbonate, copper carbonate, zinc sulfide, tin sulfide, copper sulfide, zinc chloride, tin chloride, copper chloride, zinc borate, tin borate, copper borate, or a mixture thereof.

12. The laminate of claim 1, where said second layer includes a thermoplastic polymer or blend of thermoplastic polymer, and a filler dispersed therein.

13. The laminate of claim 1, where said first layer includes inorganic nano- particulates dispersed within a thermoplastic polymer comprising a propylene- based polymer, a low density polyethylene, and a plastomer.

14. The laminate of claim 1, where said second layer includes a thermoplastic polymer comprising a propylene-based polymer, a low density polyethylene, and a plastomer.

15. A roof comprising: a roof deck; and a flexible membrane, where said flexible laminate includes inorganic nano-particulates .

16. The roof of claim 15, where said flexible laminate includes a first layer including a thermoplastic resin having inorganic nano-particulates dispersed therein; and a second layer compositionally distinct from the first layer, where said second layer includes less than about 1% by weight inorganic nano-particulates.

17. The roof of claim 15, where said inorganic nano-particulates include a metal oxide, a metal carbonate, a metal sulfide, a metal salt, a metal borate, or a mixture thereof.

18. The roof of claim 15, where said inorganic nano-particulates include zinc oxide, tin oxide, copper oxide, zinc carbonate, tin carbonate, copper carbonate, zinc sulfide, tin sulfide, copper sulfide, zinc chloride, tin chloride, copper chloride, zinc borate, tin borate, copper borate, or a mixture thereof.