Roofing membranes including cement kiln dust

Abstract

The invention generally relates to EPDM roofing membranes that include cement kiln dust. More specifically, described is a roofing membrane comprising a cured EPDM rubber matrix having cement kiln dust dispersed therein. Also described are a roof system including the roofing membrane and the use of cement kiln dust in a cured EPDM roofing membrane to increase fire resistance.

Description

ROOFING MEMBRANES INCLUDING CEMENT KILN DUSTFIELD OF THE INVENTION

[0001] The present invention generally relates to EPDM roofing membranes that include cement kiln dust.BACKGROUND OF THE INVENTION

[0002] Single-ply roofing membranes fabricated from ethylene-propylene-diene terpolymer (EPDM rubber) are widely used to cover flat or low-sloped roofs. Among the several characteristics that these membranes must exhibit in order to function as a roofing membrane is flame resistance. In this respect, roof systems that including single-ply membranes such as EPDM roofing membranes are classified by ASTM E108-20a (2020) or similar standards such as UL 790 (2014). These classification methodologies include multiple tests that ultimately provide a rating (i.e. Class A, B or C), which suggests the flame resistance of the system. Specifically, where membrane systems are installed over a non-combustible deck, the system is only subjected to the spread of flame test, while membrane systems installed over a combustible desk are subjected to the spread of flame test, the intermittent flame test, and the burning brand test.

[0003] While several factors, such as the nature of the deck, play into the ultimate classification, the flame resistance of the EPDM membrane may play a major role in the fire resistance of the system. The flame resistance of EPDM membranes was historically achieved by the addition of flame retardants such halogenated compounds (e.g. decabromodiphenyl oxide). More recently, EPDM membranes with advantageous flame resistance have been achieved by the addition of mineral fillers such as clay, talc, and mica. While useful, limitations exist with regard to the flame resistance of these mineral-filled membranes. That is, there are limits to the level of mineral filler that can be included within the membrane because the mechanical properties of the membrane are deleteriously impacted at higher loadings of these fillers. This is especially problematic for non-reinforced membranes. As a result, advantageous fire ratings are difficult to achieve for roof systems with higher slopes (e.g. 3: 12 as opposed to 0.25: 12 pitched roofs).SUMMARY OF THE INVENTION

[0004] One or more embodiments of the present invention provide a roofing membrane comprising a cured EPDM rubber matrix having cement kiln dust dispersed therein.

[0005] Other embodiments of the present invention provide the use of cement kiln dust in a cured EPDM roofing membrane to increase fire resistance.DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0006] Embodiments of the present invention are based, at least in part, upon the discovery of EPDM roofing membranes including cement kiln dust (CKD). The membranes of one or more embodiments provide roof systems with advantageous ratings under ASTM El 08 (2020) (20A) (and / or UL 790 (2014)). Moreover, these benefits have been realized without a deleterious impact on other characteristics of the membrane, and therefore membranes of this invention meet the performance standards of ASTM D4637-15 (reapproved 2021). Additionally, since CKD is considered a by-product waste that is typically landfilled, the present invention advantageously provides a method for recycling CKD into useful products.Membrane Construction

[0007] As suggested above, the membranes of this invention, which may also be referred to as membrane panels or sheets, are EPDM roofing membranes, which generally include a planar body formed from a cured rubber matrix in which other constituents, such as the cement kiln dust, may be dispersed. The membranes may be of a type generally classified as single-ply roofing membranes, and they are therefore adapted to provide a weatherproof exterior surface to a roofing system. The membranes may optionally include a fabric reinforcement (e.g. scrim) embedded within the membrane; i.e. the fabric is sandwiched between rubber layers. In other embodiments, the membranes are without fabric reinforcement. In one or more embodiments, the EPDM sheets meet the performance standards of ASTM D 4637 / D4637M-15 (Reapproved 2021).

[0008] In one or more embodiments, the membranes may be characterized by a thickness of greater than 20, in other embodiments greater than 40, and in other embodiments greater than 50 mils. In these or other embodiments, the membranes are characterized by a thickness of less than 120, in other embodiments less than 100, and in other embodiments less than 90mils. In one or more embodiments, the membranes have a thickness of from about 20 to about 100 mils, in other embodiments from about 35 to about 95 mils, and in other embodiments from about 45 to about 90 mils. In one or more embodiments, the membranes may be characterized by a width of greater than 5, in other embodiments greater than 10, in other embodiments greater than 20, and in other embodiments greater than 30 feet. In these or other embodiments, the membranes are characterized by a width of less than 100, in other embodiments less than 80, and in other embodiments less than 60 feet. In one or more embodiments, the membranes have a width of from about 5 to about 100, in other embodiments from about 10 to about 100, in other embodiments from about 20 to about 80, and in other embodiments from about 30 to about 60 feet.

[0009] In one or more embodiments, the membranes, although commonly referred to as single-ply roofing membranes, may include two or more rubber layers that are mated together with an optional scrim disposed between the layers. In particular embodiments, the respective layers may be compositionally distinct. For example, first and second rubber sheets (i.e. layers) may be formed from first and second respective rubber compositions, and then the respective sheets can be mated and further calendered or laminated to one another, optionally with a reinforcing fabric therebetween. The skilled person will recognize, however, that these layers may be integral to the extent that the calendering and / or curing process creates an interface, at some level, and the layers are generally inseparable. Nonetheless, reference can be made to the individual layers, especially where the layers derive from distinct compositions. Reference may also be made a multi-layered sheet. Relative to the overall thickness, the thickness of the respective layers (regardless of whether or not they are compositionally distinct), may vary. In one or more embodiments, the thickness of the individual layers of a membrane panel including two rubbers layers may be half or approximately half of the overall thickness less any increase in thickness resulting from the scrim.

[0010] In one or more embodiments, each layer of a multi-layered membrane or sheet may include cement kiln dust according to the present invention. In other embodiments, a first layer may include cement kiln dust and a second layer is devoid or substantially devoid of cement kiln dust. Substantially devoid refers to the absence of that amount of cement kiln dust that would otherwise have an appreciable impact on practice of the present invention. For example, in one embodiment, the membrane of the invention is a calendered sheet wherein afirst composition including cement kiln dust is calendared to form a first layer of the membrane, and a second composition that devoid or substantially devoid of cement kiln dust is calendared to form a second layer of the membrane.

[0011] In one or more embodiments, the membranes of the present invention are two-layered membranes, wherein the first membrane is black in color and the second layer is non-black in color (e.g. white or generally white). As those skilled in the art appreciate, the black layer can derive from a black composition that would generally include carbon black as a filler. The black layer includes cement kiln dust as contemplated by the present invention. The white layer can derive from a white composition that would generally include non-black fillers such as silica, titanium dioxide, and / or clay. White EPDM membranes or membranes having a white EPDM layer are known in the art as disclosed in U.S. Serial No 12 / 389,145, which is incorporated herein by reference.Membrane Composition

[0012] The composition of the membranes of this invention can be understood with reference to the constituents of the vulcanizable (i.e. curable) composition used to form the membranes. As will be described in greater detail below, the vulcanizable composition is formed and shaped into the desired shape of the membrane, and then the membrane is cured to form the cured rubber matrix in which the other constituents, such as the cement kiln dust, are dispersed. The skilled person also understands that a membrane may be constructed by combining two or more layers (typically prior to curing), and each layer may derive from separate vulcanizable compositions. Where the membranes of this invention are prepared by combining multiple rubbers layers, at least one of the layers may include cement kiln dust according to embodiments of this invention. The other layers may be conventional in nature and are adapted to be compatible with the one or more layers including the cement kiln dust. In particular embodiments, the one or more of the other layers may be devoid of cement kiln dust.

[0013] In one or more embodiments, the vulcanizable compositions include EPDM, a curative for the EPDM, cement kiln dust, and a filler. Additionally, the vulcanizable compositions may optionally include and extender, oil, wax, antioxidant, antiozonant, and a combination of two or more thereof. In particular embodiments, the vulcanizable compositions are devoid of halogenated compounds, particularly halogenated flameretardants. In particular embodiments, the vulcanizable compositions include a complementary flame retardant. In sub embodiments thereof, the complementary flame retardant is a non-halogenated flame retardant.EPDM Rubber

[0014] The skilled person understands that EPDM refers to an olefinic terpolymer rubber polymer (which may also be referred to as a curable polymer or an elastomeric terpolymer). In one or more embodiments, the olefinic terpolymer includes mer units that derive from ethylene, a-olefin, and optionally diene monomer. Useful a-olefins include propylene. In one or more embodiments, the diene monomer may include dicyclopentadiene, alkyldicyclopentadiene, 1,4-pentadiene, 1,4-hexadiene, 1,5 -hexadiene, 1,4-heptadiene, 2- methyl-l,5-hexadiene, cyclooctadiene, 1,4-octadiene, 1,7-octadiene, 5-ethylidene-2- norbomene, 5-vinyl-2-norbornene, 5-n-propylidene-2-norbornene, 5-(2-methyl-2-butenyl)-2- norbornene, and mixtures thereof. Olefinic terpolymers and methods for their manufacture are known as disclosed at U.S. Patent No. 3,280,082 as well as U.S. Publication No. 2006 / 0280892, both of which are incorporated herein by reference. Furthermore, olefinic terpolymers and methods for their manufacture as related to non-black membranes are known as disclosed in co-pending U.S. Application Nos. 12 / 389,145, 12 / 982,198, and 13 / 287,417, which are also incorporated herein by reference. For purposes of this specification, elastomeric terpolymers may simply be referred to as EPDM or EPDM rubber.

[0015] In one or more embodiments, the elastomeric terpolymer may include greater than 55 wt %, and in other embodiments greater than 64 wt % mer units deriving from ethylene; in these or other embodiments, the elastomeric terpolymer may include less than 71 wt %, and in other embodiments less than 69 wt %, mer units deriving from ethylene. In one or more embodiments, the elastomeric terpolymer may include greater than 1.5 wt %, in other embodiments greater than 2.4 wt %, mer units deriving from diene monomer; in these or other embodiments, the elastomeric terpolymer may include less than 6 wt %, in other embodiments less than 5 wt %, and in other embodiments less than 4 wt %, mer units deriving from diene monomer. In one or more embodiments, the balance of the mer units derive from propylene or other a-olefins. The elastomeric terpolymers may be characterized and include cure systems as is known in the art and as disclosed in U.S. Publication No. 2006 / 0280892, incorporated herein by reference.

[0016] As is known in the art, it is within the scope of the present invention to blend low Mooney EPDM terpolymers with high Mooney EPDM terpolymers to reduce the overall viscosity of the membrane compound. In other words, EPDM terpolymers with different molecular weights may be utilized to accommodate processing.Curative

[0017] As indicated above, the vulcanizable composition includes a curative that serves to cure or crosslink the rubber. Those skilled in the art appreciate that EPDM can be cured by using numerous techniques such as those that employ sulfur cure systems, peroxide cure systems, and quinone-type cure systems. The sulfur cure systems may be employed in combination with vulcanizing accelerators.

[0018] In one or more embodiments, sulfur and sulfur-containing cure systems may be used (optionally together with an accelerator). Suitable amounts of sulfur can be readily determined by those skilled in the art. In one or more embodiments from about 0.5 to about 1.5 part by weight (pbw) sulfur per 100 parts by weight rubber (phr) may be used. The amount of accelerator can also be readily determined by those skilled in the art.

[0019] Useful vulcanizing accelerators include thioureas such as ethylene thiourea, N,N- dibutylthiourea, N,N-diethylthiourea and the like; thiuram monosulfides and disulfides such as tetramethylthiuram monosulfide (TMTMS), tetrabutylthiuram disulfide (TBTDS), tetramethylthiuram disulfide (TMTDS), tetraethylthiuram monosulfide (TETMS), dipentamethylenethiuram hexasulfide (DPTH) and the like; benzothiazole sulfenamides such as N-oxydiethylene-2 -benzothiazole sulfenamide, N-cyclohexyl-2 -benzothiazole sulfenamide, N,N-diisopropyl-2-benzothiazolesulfenamide, N-tert-butyl-2-benzothiazole sulfenamide (TBBS), and the like; other thiazole accelerators such as 2-mercaptobenzothiazole (MBT), benzothiazyl disulfide (MBTS), N,N-diphenylguanidine, N,N-di-(2-methylphenyl)-guanidine, 2-(morpholinodithio)benzothiazole disulfide, zinc 2-mercaptobenzothiazole and the like; dithiocarbamates such as tellurium diethyldithiocarbamate, copper dimethyldithiocarbamate, bismuth dimethyldithiocarbamate, cadmium di ethyl dithiocarbamate, lead dimethyldithiocarbamate, sodium butyldithiocarbamate, zinc diethyldithiocarbamate, zinc dimethyldithiocarbamate, zinc dibutyldithiocarbamate (ZDBDC), dithiophosphates, and mixtures thereof. Sulfur donor-type accelerators (e.g. di-morpholino disulfide and alkylphenol disulfide) may be used in place of elemental sulfur or in conjunction with elemental sulfur if desired.

[0020] Examples of suitable peroxides that can be used as curing agents or co-curing agents include alpha-cumyl hydroperoxide, methylethylketone peroxide, hydrogen peroxide, acetylacetone peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2,5-bis(t-butyl peroxy)-2, 5 -dimethylhexene, lauryl peroxide, benzoyl peroxide, 2,4-dichlorobenzoyl peroxide, dibenzoyl peroxide, bis(p-monomethylene-benzoyl) peroxide, bis(p-nitrobenzoyl) peroxide, phenylacetyl peroxide, and mixtures thereof.

[0021] Examples of inorganic peroxides that can be used as co-curing agents with p-quinone dioxime include lead peroxide, zinc peroxide, barium peroxide, copper peroxide, potassium peroxide, silver peroxide, sodium peroxide, calcium peroxide, metallic peroxyborates, peroxychromates, peroxydicarbonates, peroxydiphosphates, peroxy di sulfates, peroxygermanates, peroxymolybdates, peroxynitrates, magnesium peroxide, sodium pyrophosphate peroxide, and mixtures thereof.

[0022] Examples of poly sulfide activators for the quinone-type co-curing agents include calcium polysulfide, sodium polysulfide, as well as organic polysulfides having the general formula R— (S)x— R, wherein R is a hydrocarbon group and x is a number from 2-4. Examples of organic polysulfides are disclosed in U.S. Patent No. 2,619,481, which is incorporated herein by reference.

[0023] Where radiation curing is employed to crosslink the rubber, an ionizing crosslinking promoters may be included in lieu of or in addition to the curatives described above. These ionizing crosslinking promoters may include, but are limited to, liquid high- vinyl 1,2- polybutadiene resins containing 90 percent 1,2-vinyl content, ethylene glycol dimethacrylate, dicumyl peroxide (typically about 98 percent active), and pentaerythritol resin prepared from tall oil.Cement Kiln Dust

[0024] As indicated above, the vulcanizable composition includes cement kiln dust (CKD), which may also be referred to as flue dust or Portland cement. The skilled person understands that cement kiln dust may include uncalcined raw materials along with partially calcined materials. The cement kiln dust employed in practice of this invention can be obtained as aby-product of cement production. As understood by those skilled in the art, CKD is removed from the gas stream of the cement product process and collected, for example, in a dust collector. The skilled person also appreciates that cement kiln dust is commonly landfilled as waste.

[0025] The chemical composition of CKD varies depending on a number of factors including, but not limited to, the particular kiln feed, the efficiency of the cement production operation, and the associated dust collection systems. Generally, CKD includes calcium carbonate, calcium oxide, clays, shales, quartz, magnesium oxide, and sulfate salts. Additionally, CKD may include dolomite, feldspars, fly ash, iron oxides, CaF2, CaO, glasses of SiCh, AI2O3, and Fe20s, Ca(OH)2, CaSCU, KC1, K2CO3, K2SO4, Na2SO4, and other constituents typically found in Portland cement. The skilled person appreciates that calcium carbonate may also be referred to as chalk or limestone, and it may be present in the form of calcite and aragonite. Calcium oxide may also be referred to as lime and quicklime. Quartz may also be referred to as silica, crystalline quartz, silicon dioxide, silica dust, quartz powder. Magnesium oxide may also be referred to as calcined magnesite and magnesia.

[0026] In one or more embodiments, the CKD employed in practicing the present invention may include from about 10 to 80 wt %, in other embodiments from about 15 to about 75 wt %, and in other embodiments from about 20 to about 70 wt % calcium carbonate per weight of CKD. In these or other embodiments, useful CKD may include from about 5 wt % to about 50 wt %, in other embodiments from about 10 to about 45 wt %, and in other embodiments from about 15 to about 40 wt % calcium oxide per weight of CKD. In these or other embodiments, useful CKD may include from about 1 wt % to about 10 wt %, in other embodiments from about 2 to about 9 wt %, and in other embodiments from about 3 to about 8 wt % quartz per weight of CKD. In these or other embodiments, useful CKD may include from about 0.5 wt % to about 3 wt %, in other embodiments from about 1 to about 2.5 wt %, and in other embodiments from about 1.5 to about 2 wt % magnesium oxide per weight of CKD.

[0027] Since the characteristics of CKD can vary widely with respect to chemical, mineralogical, and physical properties, which variations can depend upon the raw material, type of operation, dust collection facility, and type of fuel used at the plant generating the CKD, the CKD can be further processed to obtain consistent chemical, mineralogical, and / or physical properties. The skilled person appreciates that a variety of wet and dry processingmethods may be used to alter the chemical, mineralogical, and physical properties of the CKD prior to use in the present invention. For example, the mean particle size of the cement kiln dust can be altered to obtain a size suitable for use in the present invention. For example, the mean particle size of the cement kiln dust may be reduced from its original size. In one or more embodiments, the CKD may have a mean particle size that is at least 5% less than its original size (e.g. about 5% to about 95% of its original size). For example, the mean particle size may be reduced to a size ranging between any of and / or including any of about 5%, about 10%, about 15%, about 20%, about 25%, about 30%, about 35%, about 40%, about 45%, about 50%, about 55%, about 60%; about 65%, about 70%, about 75%, about 80%, about 90%, or about 95% of its original size.

[0028] In one or more embodiments, the mean particle size (i.e. dso values as measured by particle size analyzers) of the CKD employed in the present invention (either as a processed or unprocessed material feed) may be from about 1 to about 350 pm, or in other embodiments from about 0.1 to about 15 pm, and in other embodiments from about 0.1 to about 10 pm, or from about 1 to about 10 pm. In one or more embodiments, the mean particle size may be less than 15, in other embodiments less than 10, in other embodiments less than 7, in other embodiments less than 5, in other embodiments less than 3, in other embodiments less than 2, and in other embodiments less than 1 pm.

[0029] In one or more embodiments, the CKD used in the present invention may have a D90 (which can be determined by a Malvern Mastersizer® 2000) of less than 100 pm, in other embodiments less than 75 pm, in other embodiments less than 50 pm, in other embodiments less than 40 pm, in other embodiments less than 35 pm, and other embodiments less than 30 pm. In one or more embodiments, the complementary filler may be characterized by a D90 particle size of from about 1 to about 100 pm, in other embodiments from about 5 to about 75 pm, and in other embodiments from about 10 to about 50 pm.Other Fillers

[0030] As mentioned above, the vulcanizable compositions of the present invention may include filler other than CKD, which fillers may be referred to as complementary fillers. These complementary fillers may include those conventionally employed in the art, as well as combinations of two or more of these fillers.

[0031] In one or more embodiments, the complementary fillers may be characterized by a mean particle size (i.e. dso values as measured by particle size analyzers) of from about 0.01 to about 1.5 pm, in other embodiments from about 0.05 to about 1 pm, and in other embodiments from about 0.1 to about 0.75 pm. In one or more embodiments, the mean particle size of the complementary filler may be less than 1.5, in other embodiments less than 1.2, in other embodiments less than 1.1, in other embodiments less than 1.0, in other embodiments less than 0.9, in other embodiments less than 0.8, and in other embodiments less than 0.7 pm.

[0032] In one or more embodiments, the complementary filler may be characterized by a D90 particle size (which can be determined by a Malvern Mastersizer® 2000) of less than 1.5 pm, in other embodiments less than 1.3 pm, in other embodiments less than 1.2 pm, in other embodiments less than 1.1 pm, in other embodiments less than 1.0 pm, and other embodiments less than 0.9 pm. In one or more embodiments, the complementary filler may be characterized by a D90 particle size of from about 0.01 to about 1.5 pm, in other embodiments from about 0.05 to about 1 pm, and in other embodiments from about 0.1 to about 0.75 pm.

[0033] In one or more embodiments, the filler may include carbon black. Examples of useful carbon blacks include those generally characterized by average industry-wide target values established in ASTM D-1765-21 (2021). Exemplary carbon blacks include GPF (General- Purpose Furnace), FEF (Fast Extrusion Furnace), and SRF (Semi-Reinforcing Furnace). One particular example of a carbon black is N650 GPF Black, which is a petroleum-derived reinforcing carbon black having an average particle size of about 60 nm and a specific gravity of about 1.8 g / cc. Another example is N330, which is a high abrasion furnace black having an average particle size about 30 nm, a maximum ash content of about 0.75%, and a specific gravity of about 1.8 g / cc.

[0034] Other useful fillers including clay, mica, and talc, such as those disclosed in U.S. Publication No. 2006 / 0280892, which is incorporated herein by reference. Still other useful fillers include silica, which may be used in conjunction with a coupling agent as disclosed, for example, in U.S. Publication Nos. 2015 / 0038031 and 2018 / 0179759, which are incorporated herein by reference. In one or more embodiments, useful fillers include clays, silicates, titanium dioxide, talc (magnesium silicate), mica (mixtures of sodium and potassium aluminum silicate), alumina trihydrate, antimony trioxide, titanium dioxide, silica, calciumborate ore, and mixtures thereof. Suitable clays may include airfloated clays, water-washed clays, calcined clays, surface-treated clays, chemically-modified clays, and mixtures thereof. Suitable silicates may include synthetic amorphous calcium silicates, precipitated, amorphous sodium aluminosilicates, and mixtures thereof. Suitable silica (silicon dioxide) may include wet-processed, hydrated silicas, crystalline silicas, and amorphous silicas (noncrystalline).Flame Retardants

[0035] Flame retardants those compounds that increases the bum resistivity of the EPDM membranes.

[0036] Useful complementary flame retardants include char-forming and decomposition flame retardants. Those skilled in the art understand that char-forming flame retardants operate by forming a char-layer across the surface of a specimen when exposed to a flame. Decomposition flame retardants, on the other hand, operate by releasing water (or other flame extinguishing compound) upon thermal decomposition of the flame-retardant compound. As indicated above, the complementary flame retardants may also be categorized as halogenated flame retardants or non-halogenated flame retardants.

[0037] Exemplary non-halogenated flame retardants that may be used as complementary flame retardants include magnesium hydroxide, aluminum trihydrate, zinc borate, ammonium polyphosphate, melamine polyphosphate, antimony oxide (Sb2O3), and expandable graphite. Ammonium polyphosphate may be used together as a polyol masterbatch. Those flame retardants from the foregoing list that are believed to operate by forming a char layer include ammonium polyphosphate and melamine polyphosphate.Extenders

[0038] As mentioned above, the vulcanizable compositions of the present invention may optionally include extenders. Useful extenders include paraffinic, naphthenic oils, and mixtures thereof. These oils may be halogenated as disclosed in U.S. Patent No. 6,632,509, which is incorporated herein by reference. In one or more embodiments, useful oils are generally characterized by, low aromaticity, low volatility and a flash point of more than about 550 °F. Useful extenders are commercially available. One particular extender is a paraffinic oil available under the tradename SUNPAR™ 2280 (Sun Oil Company). Anotheruseful paraffinic process oil is Hyprene P150BS, available from Ergon Oil Inc. of Jackson, MS.Other Constituents

[0039] In addition to the foregoing constituents, the vulcanizable composition of this invention may also optionally include mica, coal filler, ground rubber, titanium dioxide, calcium carbonate, silica, homogenizing agents, phenolic resins, flame retardants, zinc oxide, stearic acid, and mixtures thereof as disclosed in U.S. Publication No. 2006 / 0280892, which is incorporated herein by reference. Certain embodiments may be substantially devoid of any one or more of these constituents.Amounts

[0040] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention (which include cement kiln dust) include from about 15 to about 55 weight percent, in other embodiments from about 20 to about 50 weight percent, in other embodiments from about 24 to about 36 weight percent, and in other embodiments from about 28 to about 32 weight percent rubber (e.g., EPDM) based on the entire weight of the vulcanizable composition.

[0041] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention include from about 100 to about 350, in other embodiments from about 120 to about 330, in other embodiments from about 150 to about 300 parts by weight (pbw) total filler per 100 parts by weight rubber (phr) (e.g. EPDM).

[0042] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention include from about 25 to about 125, in other embodiments from about 30 to about 110, in other embodiments from about 50 to about 100 parts by weight (pbw) oil per 100 parts by weight rubber (phr) (e.g. EPDM).

[0043] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention include from about 1 to about 150, in other embodiments from about 10 to about 150, in other embodiments from about 20 to about 150, in other embodiments from about 40 to about 150, and in other embodiments from about 80 to about 150 parts by weight (pbw) cement kiln dust per 100 parts by weight rubber (phr) (e.g.EPDM). In certain embodiments, the vulcanizable compositions of this invention include less than 200 pbw, in other embodiments less than 150 pbw, and in other embodiments less than 100 pbw cement kiln dust phr. In these or other embodiments, the vulcanizable compositions of this invention include greater than 1 pbw, in other embodiments greater than 10 pbw, and in other embodiments greater than 20 pbw cement kiln dust phr.

[0044] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention may include a CKD and a complementary filler. In one or more embodiments, the weight ratio or CKD to complementary filler is from about 0.3:1 to about 1.8: 1, in other embodiments from about 0.5 to about 1.5: 1, in other embodiments from about 0.7: 1 to about 1.3: 1, and in other embodiments from about 0.9: 1 to about 1.1 :1.

[0045] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention may include from about 40 to about 100 pbw, in other embodiments from about 50 to about 95 pbw, and in other embodiments from about 55 to about 85 parts by weight carbon black per 100 pbw phr. Certain embodiments may be substantially devoid of carbon black.

[0046] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention may include from about 0 to about 150 pbw, in other embodiments from about 0 to about 100 pbw, and in other embodiments from about 40 to about 80 pbw clay per 100 pbw phr. Certain embodiments may be substantially devoid of clay.

[0047] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention may include from 5 to about 60 pbw, in other embodiments from about 10 to about 40 pbw, and in other embodiments from about 20 to about 25 pbw talc per 100 pbw phr. Certain embodiments may be substantially devoid of talc.

[0048] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention may include from about 55 to about 95 pbw, in other embodiments from about 60 to about 85 pbw, and in other embodiments from about 65 to about 80 pbw extender per 100 pbw phr. Certain embodiments may be substantially devoid of extender.

[0049] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention include from about 12 to about 25 pbw mica per 100 pbw phr. In other embodiments, the membrane includes less than 12 pbw phr mica, and in other embodiments less than 6 pbw mica phr. In certain embodiments, the membrane is devoid of mica.

[0050] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention may include from about 10 to about 100 pbw silica phr. In other embodiments, the vulcanizable compositions include less than 70 pbw silica phr, and in other embodiments less than 55 pbw silica phr. In certain embodiments, the membrane is devoid of silica.

[0051] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention include from about 2 to about 10 pbw homogenizing agent phr. In other embodiments, the membrane includes less than 5 pbw homogenizing agent phr, and in other embodiments less than 3 pbw homogenizing agent phr. In certain embodiments, the membrane is devoid of homogenizing agent.

[0052] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention include from about 2 to about 10 pbw phenolic resin phr. In other embodiments, the membrane includes less than 4 pbw phenolic resin phr, and in other embodiments less than 2.5 pbw phenolic resin phr. In certain embodiments, the membrane is devoid of phenolic resin.

[0053] In one or more embodiments, the vulcanizable compositions used to prepare the one or more layers of the membranes of this invention (or one or more layers of a multi-layered membrane) including cement kiln dust are devoid or substantially devoid of halogencontaining flame retardants. In one or more embodiments, the membranes or the layers of a membrane including cement kiln dust include less than 5 pbw, in other embodiments less than 3 pbw, and in other embodiments less than 0.1 pbw halogen-containing flame retardant phr.In particular embodiments, the membranes of the present invention are substantially devoid of DBDPO.Methods of Manufacture

[0054] Practice of embodiments of the present invention is not limited by the methods used to prepare the vulcanizable compositions or the roofing membranes of this invention. For example, convention techniques can be employed, which includes preparing the vulcanizable compositions by using conventional batch mixing techniques, calendaring a sheet, fabricating a green membrane, curing the green membrane to form a cured membrane, and then optionally finishing the membrane to ultimately form a roll for shipping.

[0055] Conventional rubber mixing, also referred to as rubber compounding, can employ a variety of mixing equipment such as Brabender mixers, Banbury mixers, Sigma-blade mixers, two-roll mills, or other mixers suitable for forming viscous, relatively uniform admixtures. Mixing techniques depend on a variety of factors such as the specific types of polymers used, and the fillers, processing oils, waxes and other ingredients used. In one or more embodiments, the ingredients can be added together in a single shot. In other embodiments, some of the ingredients such as fillers, oils, etc. can first be loaded followed by the polymer. In other embodiments, a more conventional manner can be employed where the polymer added first followed by the other ingredients. These techniques are generally known in the art as disclosed in U.S. Publication Nos. 2014 / 0373467, 2006 / 0280892, 2008 / 0097004, and 2016 / 0221309, which are incorporated herein by reference.

[0056] Mixing cycles generally range from about 2 to 6 minutes. In certain embodiments an incremental procedure can be used whereby the base polymer and part of the fillers are added first with little or no process oil, the cement kiln dust, the remaining fillers and process oil are added in additional increments. In other embodiments, part of the EPDM can be added on top of the fillers, plasticizers, etc. This procedure can be further modified by withholding part of the process oil, and then adding it later. In one or more embodiments, two-stage mixing can be employed.

[0057] The sulfur cure package (sulfur / accelerator) can be added near the end of the mixing cycle and at lower temperatures to prevent premature crosslinking of the EPDM polymer chains. When utilizing a type B Banbury internal mixer, the dry or powdery materials such as the carbon black and non-black mineral fillers (i.e., untreated clay, treated clays, talc, mica, and the like) can be added first, followed by the liquid process oil and finally the polymer (this type of mixing can be referred to as an upside-down mixing technique).

[0058] Once mixed, the rubber composition can then be formed into a sheet via calendering. The compositions of the invention can also be formed into various types of articles using other techniques such as extrusion.

[0059] Methods also exist for the continuous manufacture of vulcanizable compositions of matter that are useful for forming roofing membranes. In this regard, U.S. Publication No. 2015 / 0076743 is incorporated herein by reference.

[0060] The resultant vulcanizable compositions may be prepared in sheet form in any known manner such as by calendering or extrusion. The sheet may also be cut to a desired dimension. In one or more embodiments, the resulting admixture can be sheeted to thicknesses ranging from 5 to 200 mils, in other embodiments from 35 to 90 mils, by using conventional sheeting methods, for example, milling, calendering or extrusion. In one or more embodiments, the admixture is sheeted to at least 40 mils (0.040-inches), which is the minimum thickness specified in manufacturing standards established by the Roofing Council of the Rubber Manufacturers Association (RMA) for non-reinforced EPDM rubber sheets for use in roofing applications. Membranes of one or more embodiments meet the standards of ASTM D4637- 15 (2021). In other embodiments, the admixture is sheeted to a thickness of about 45 mils, which is the thickness for a large percentage of “single-ply” roofing membranes used commercially. The sheeting can be visually inspected and cut to the desired length and width dimensions after curing. The membranes of the present invention can be optionally reinforced with scrim. In other embodiments, the membranes are devoid of scrim. The skilled person understands that reinforcement can be included into the membrane by sandwiching the fabric between two layers of rubber sheet. Each rubber sheet may derive from the same or different vulcanizable compositions. As noted above, at least one of the rubber layers is prepared from the vulcanizable composition including cement kiln dust.

[0061] The green membrane is then subjected to curing conditions. This can take place using conventional batch procedures where the membrane is rolled and cured in an oven, optionally under pressure, such as is accomplished within an autoclave. The skilled person understands that efforts must be undertaken to ensure that the membrane does not cure to itself when rolled. For example, the green membrane can be dusted (e.g. talc) or rolled with a curing liner prior to curing. In the alternative, curing can take place continuously using known technologies. In this regard, U.S. Publication Nos. 2015 / 0076743 and 2001 / 0027224 are incorporated herein by reference.

[0062] Where the membranes of this invention include distinct layers that derive from distinct vulcanizable compositions, the vulcanizable compositions that do not include cement kiln dust can be conventional in nature. In this regard, U.S. Patent Nos. 7,175,732, 6,502,360, 6,120,869, 5,849,133, 5,389,715, 4,810,565, 4,778,852, 4,732,925, and 4,657,958 are incorporated herein by reference.Membrane Installation

[0063] The membranes of this invention may be unrolled over a roof substructure in a conventional fashion, wherein the seams of adjacent sheets are overlapped and mated by using, for example, an adhesive. The width of the seam can vary depending on the requirements specified by the architect, building contractor, or roofing contractor, and they thus do not constitute a limitation of the present invention. Seams can be joined with conventional adhesives such as, for instance, a butyl-based lap splice adhesive, which is commercially available under the tradename ELEVATE as Elevate Splice Adhesives SA- 1065. Application can be facilitated by spray, brush, swab or other means known in the art. Also, field seams can be formed by using tape and optionally a companion primer such as ELEVATE QuickSeam™ tape and Quick Prime Plus primer, both of which are commercially available from Holcim Building Envelope of Nashville, TN.

[0064] Also, as is known in the art, these membranes can be secured to the roof substructure by using, for example, mechanical fasteners, adhesives (which are often employed to prepare a fully-adhered roofing system), or ballasting. In particular embodiments, the membranes of the present invention can be formed into a composite by applying a layer of pressure-sensitive adhesive (e.g. UV-curable adhesive) as disclosed in U.S. Patent Nos. 10,065,394, 10,132,082, 10,260,237, and 10,370,854. Furthermore, the membranes of this invention are useful in combination with insulation or coverboards or in composite boards as disclosed in U.S. Patent No. 7,972,688, which is incorporated herein by reference. It is also contemplated to use the concepts of the present invention in EPDM flashings such as those disclosed in U.S. Patent No. 5,804,661, which is also incorporated herein by reference.Roof System

[0065] As indicated above, the membranes of the present invention can be used to create a roof system. These roof systems may include flat or low-slope roofing system. Sloped roofsystems typically have a slope of at least 0.25: 12 (rise over run), and can include roofs with slope of 1 : 12, or 2: 12 (low sloped), or 3: 12, or 5: 12.

[0066] Exemplary roof systems include a roof deck, an insulation layer, an optional cover board layer, and a membrane layer. The membrane layer forms the outermost element of the system, with the cover board layer disposed below the membrane, the insulation layer disposed below the cover board layer, and the insulation layer disposed above the deck.

[0067] Practice of this invention is not limited by the selection of any particular roof deck. Accordingly, the roofing systems of this invention can include a variety of roof decks including both combustible and non-combustible decks. Exemplary roof decks include concrete pads, steel decks, wood beams, and foamed concrete decks.

[0068] Practice of the invention is not necessarily limited by the selection of the insulation layer or the cover board layer. For example, the insulation layer can include polyisocyanurate foam, which may be provided as board stock. In this respect, U.S. Publication Nos.2004 / 0082676, 2004 / 0102537, and 2022 / 0049063 are incorporated herein by reference.Likewise, cover board layer 36 can include a variety of materials include wood strand board, gypsum, perlite, and high-density foam such as polyisocyanurate board. In this respect, U.S. Publication Nos. 2006 / 0179749 and 2001 / 0214387 are incorporated herein by reference.

[0069] The various layers of the system can be secured to the deck by using various known techniques. For example, in one or more embodiments, one or more of the layers can be mechanically fastened to the roof deck. In lieu or in combination therewith, one or more layers can be adhesively secured to the layer disposed immediately below. For example, the insulation layer and / or the cover board layer can be mechanically fastened and then the membrane layer can be adhesively fastened.Membrane and System Performance Standards

[0070] In one or more embodiments, the membranes of the invention can be used to create a Class A roof system over a non-combustible deck pursuant to ASTM E108-20a (2020). In one or more embodiments, the Class A roof system has a slope of greater than or equal to 0.25: 1 : 12, in other embodiments greater than or equal to 2: 12, in other embodiments greater than 3: 12, and in other embodiments greater than 5: 12. In these or other embodiments, the membranes can be used to create a Class A roof system over a combustible deck pursuant toASTM E108-2oa (2020). In one or more embodiments, the Class A roof system has a slope of greater than or equal to 1 : 12, in other embodiments greater than or equal to 2: 12.

[0071] In one or more embodiments, the membranes of the present invention meet the performance standards of ASTM D 4637 / D4637M - 15 (reapproved 2021).

[0072] In order to demonstrate the practice of the present invention, the following examples have been prepared and tested. The examples should not, however, be viewed as limiting the scope of the invention. The claims will serve to define the invention.EXAMPLES

[0073] In order to demonstrate the practice of the present invention, the following examples have been prepared and tested. The examples should not, however, be viewed as limiting the scope of the invention. The claims will serve to define the invention.

[0074] Cement kiln dust (CKD) was obtained and analyzed using a Malvern Mastersizer® 2000 particle size analyzer. The results for the particle size distribution of the CKD are included in Table I.Table IExamples 1-4

[0075] Four rubber formulations were prepared and tested for processing properties. The formulations were mixed by employing a two-step mixing procedure. The rubber formulation used for each of the samples was the same as generally shown in Table II. The various ingredients are shown in parts by weight per 100 parts by weight of the rubber (phr).Table II

[0076] The properties of uncured compounds of Examples 1-4 are included in Table III.Table III

[0077] The properties of vulcanizates of Examples 1-4 are included in Table IV.Table IV

[0078] 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

CLAIMS1. A roofing membrane comprising: a cured EPDM rubber matrix including cement kiln dust dispersed therein.

2. The roofing membrane of claim 1, where the membrane is multi-layered single ply membrane, and where the cured EPDM rubber matrix having cement kiln dust dispersed therein forms at least one layer of the membrane.

3. The roofing membrane of any of the previous claims, where the cured EPDM rubber matrix includes from about 1 to about 150 parts by weight cement kiln dust per 100 parts by weight rubber.

4. The roofing membrane of any of the previous claims, where EPDM is sulfur cured.

5. The roofing membrane of any of the previous claims, where the cured EPDM rubber matrix includes carbon black dispersed therein.

6. The roofing membrane of any of the previous claims, where the cured EPDM rubber matrix includes silica dispersed therein.

7. The roofing membrane of any of the previous claims, where the cured EPDM rubber matrix includes clay dispersed therein.

8. The roofing membrane of any of the previous claims, where the cured EPDM rubber matrix includes a flame retardant dispersed therein.

9. The roofing membrane of any of the previous claims, where the cured EPDM rubber matrix is devoid of flame retardant other than the cement kiln dust.

10. The roofing membrane of any of the previous claims, where the cement kiln dust has a D90 particle size of less than 100 pm.

11. The roofing membrane of any of the previous claims, where the cement kiln dust is modified cement kiln dust.

12. The roofing membrane of any of the previous claims, where the cement kiln dust is non-modified cement kiln dust.

13. The roofing membrane of any of the previous claims, where the cured EPDM rubber matrix includes cement kiln dust and a complementary filler, where the cement kiln dust and the complementary filler are present at a weight ratio of from about 0.3 : 1 to about 1.8:1.

14. The roofing membrane of any of the previous claims, where the cement kiln dust is a filler, where the EPDM rubber matrix includes two more fillers, and where the cured EPDM rubber matrix includes from about 100 to about 350 parts by weight filler per 100 parts by weight rubber.

15. The roofing membrane of any of claims 13 or 14, where the complementary filler is selected from the group consisting of clay, mica, talc, and silica.

16. The roofing membrane of any of the previous claims, where the membrane meets the performance standard of ASTM D 4637-15.

17. The roofing membrane of any of the previous claims, where the membrane is fabric reinforced.

18. The roofing membrane of any of the previous claims, where the membrane has a thickness of from about 508 to about 2540 pm (about 20 to about 100 mils).

19. A roof system including the roofing membrane of any of the preceding claims.

20. The roof system of claim 19, where the roof system includes combustible deck.

21. The roof system of any of claims 19 or 20, where the roof system includes a noncombustible deck.

22. The roof system of any of claims 19 to 21, where the roof system is a Class A roof system according to ASTM E108-20a.

23. The roof system of any of claims 19 to 22, where the roof system has a slope of 0.25: 12 or more.

24. The use of cement kiln dust in a cured EPDM roofing membrane to increase fire resistance.

Images