Patent Description:
In a polymer-modified asphalt composition, an asphalt is modified with one or more epoxide-containing ethylene copolymers. The polymer-modified asphalt composition is useful as a binder in asphalt compositions for road paving and roofing.

Several patents, patent applications and publications are cited in this description in order to more fully describe the state of the art to which this invention pertains.

<NPL> and <NPL>. This study presents the results of a series of creep-recovery experiments that were conducted on asphalt binders modified with polyphosphoric acid (AC+PPA) and Elvaloy® terpolymer combined with polyphosphoric acid (AC+Elvaloy+PPA) at the temperatures of <NUM>, <NUM>, <NUM>, <NUM> and <NUM>.

The study was to compare different modifiers in two asphalt cements.

<CIT> relates to use of organic chemical additives for the preparation of warm asphalt mixtures.

<CIT> relates to a method for preparing bitumen/polymer compositions and use thereof.

<CIT> relates to an acid-reacted polymer-modified asphalt composition.

<CIT> relates to a thermoplastic polymer-linked-asphalt composition and a process for making a thermoplastic polymer-linked-asphalt.

<CIT> relates to an asphalt composition comprising or produced from asphalt, a solution of ethylene copolymer dissolved in flux oil or liquid plasticizer, and optionally a sulfur source or acid, wherein the ethylene copolymer comprises repeat units derived from ethylene and from an epoxy-containing comonomer.

<CIT> relates to polyepoxy-polymer-linked-asphalt having enhanced properties made by reacting a glycidyl-functionalized ethylene copolymer with reactive asphalt, wherein the glycidyl-functionalized ethylene copolymer has a glycidyl-containing comonomer content of <NUM> weight percent or greater.

<CIT> relates to a modified asphalt composition comprising or is produced from asphalt and phosphorous acid.

The use of bitumen in the manufacture of materials for highway and industrial applications is known. Bitumen is the main hydrocarbon binder used in the field of road construction or civil engineering. To be used as a binder in these different applications, the bitumen must have certain mechanical properties, and in particular elastic or cohesive properties. The mechanical properties of the bitumen and of the binder compositions comprising the bitumen are determined by standardized tests, such as determination of the softening point, the penetrability and the rheological characteristics in defined traction. Asphalts, which comprise the binder compositions, are performance graded (PG) by a set of specifications developed by the U. government (Strategic Highway Research Program or SHRP). For example, PG58-<NUM> asphalt provides good rut resistance at <NUM> (determined by AASHTO (American Association of State Highway Transportation Officials)) and good cold cracking resistance at -<NUM>.

In general, unmodified bitumens do not possess all of the required qualities, and it is known that the addition of acid or various polymers to these conventional bitumens forms modified bitumen compositions having mechanical qualities that are improved, in comparison with those of the conventional bitumens.

Thus, asphalt sold for paving may be modified with polymers to improved resistance to ruts, fatigue, and cracking. Moreover, improved stripping resistance from aggregate results from increases in asphalt elasticity and stiffness. Addition of polymer to asphalt increases rut resistance and improves fatigue resistance at higher temperatures. Further, the polymer type influences the asphalt's low temperature performance; however, these properties are to a large extent dependent on composition-specific properties, such as flux oil content or penetration index.

The asphalt industry classifies polymers as elastomers or plastomers. The term "plastomer" as used herein refers to a polymer that lacks of elastomeric properties. Plastomers are sometimes used to modify asphalt because they can increase its stiffness and viscosity, which improves rut resistance. Plastomers are typically considered inferior to elastomers, however, because they do not produce significant improvements in the asphalt's fatigue resistance, creep resistance, cold crack resistance, etc. Generally, including an elastomeric polymer in an asphalt improves the asphalt's low temperature performance, and plastomeric polymers detract from it. Styrene/butadiene/styrene block copolymers (SBS) are elastomeric, as are ethylene/butyl acrylate/glycidyl methacrylate terpolymer (EnBAGMA) and ethylene/vinyl ester/glycidyl methacrylate terpolymer (EEGMA), both of which are available from E. du Pont de Nemours and Company, Wilmington, Delaware, USA (DuPont) under the trademark Elvaloy® RET. Polyethylene (PE) and ethylene vinyl acetate (EVA) resins are plastomers. In fact, PE is not miscible with asphalt, so asphalt modified with PE must be continuously stirred to prevent separation. Thus, asphalt modified with PE must be prepared at the mix plant and cannot be shipped. PE therefore acts as a filler and does not meaningfully increase the softening point of asphalt.

Among the polymers commonly added to bitumens, random or block copolymers of an aromatic monovinyl hydrocarbon and a conjugated diene, and in particular of styrene and butadiene or of styrene and isoprene, are particularly effective. These polymers dissolve very easily in the bitumens and confer excellent mechanical and dynamic properties, in particular very good viscoelastic properties. <CIT> describes a method for producing bitumen/polymer compositions that comprise at least one styrene-butadiene copolymer.

The use of other polymers as additives to asphalt (bitumen) is well-known in the art. See for example <CIT> and <CIT>, wherein terpolymers derived from ethylene, an alkyl acrylate and maleic anhydride are mixed with bitumen.

Also see for example <CIT>; <CIT>; <CIT>; and <CIT>, and <CIT>, wherein reactant epoxy-functionalized, particularly glycidyl-containing, ethylene copolymers are mixed and reacted with bitumen and, as taught in <CIT> and <CIT>, with an acid catalyst or co-reactant to accelerate the rate of reaction and lower cost of the modified system. DuPont Elvaloy® RET resins (ENBAGMA and EEGMA) are excellent modifiers for asphalt and improve asphalt performance at low concentrations (<NUM> to <NUM> weight %).

<CIT> describes blends of asphalt with a combination of glycidyl-containing ethylene copolymer and a styrene-conjugated diene block copolymer.

<CIT> describes a bituminous composition comprising a bitumen in an amount ranging from <NUM> to <NUM> weight %, a carboxylic additive in an amount of from <NUM> to <NUM> weight %, and sulfur in an amount of <NUM> to <NUM> weight %, all percentages based on the weight of bitumen, carboxylic additive and sulfur, wherein the carboxylic additive is selected from carboxylic acids, carboxylic esters and carboxylic anhydrides.

<CIT> discloses a slow setting bitumen-aggregate mix for cold paving comprising a cationic oil-in-water emulsion in the presence of an emulsifier containing a tertiary amine and an acid.

It is also known that the stability of the bitumen/polymer compositions can be improved by chemically coupling the polymer with the bitumen, this improvement moreover making it possible to extend the field of use of the bitumen-polymer compositions. The cross-linked bitumen/polymer compositions have good storage stability, cohesion, elongation capacity, and resistance to aging.

Accordingly, without wishing to be held to theory, it is hypothesized that the improvement in asphalt properties with addition of Elvaloy® RET at such low concentrations is due to a chemical reaction between the Elvaloy® RET and the functionalized polar fraction of asphalt, also referred to herein as "asphaltenes. " EnBAGMA and EEGMA must be mixed with the asphalt at elevated temperatures to achieve the benefits of this reaction. Therefore, EnBAGMA and EEGMA are added to hot asphalt as pellets, which soften and melt due to the heat and the stirring. The reaction occurs with heat alone; however, acids such as polyphosphoric acid (PPA) are sometimes added to the asphalt and epoxide-containing polymer to reduce the reaction time. For example, the reaction may be completed and thorough mixing obtained in <NUM> to <NUM> hours without acid, compared to completion in <NUM> to <NUM> hours with acid. In addition, without acid the resultant polymer modified asphalt composition (PMA) may be less elastic, compared to a PMA produced with acid, as evidenced by a higher phase angle and low elastic recovery.

Disadvantageously, however, the addition of PPA to a glycidyl-containing ethylene copolymer-based PMA produced from a low-asphaltene asphalt results in gelling. Further, the amount of glycidyl-containing ethylene copolymers that can be included in such a PMA is limited, because higher amounts result in gelling. Moreover, the addition of further glycidyl-containing ethylene copolymer to an already-reacted PMA also results in gelling. Finally, the properties of some PMAs produced with glycidyl-containing ethylene copolymer and PPA degrade with aging at elevated temperatures.

It is apparent from the foregoing that it remains desirable to prepare polymer-modified asphalt compositions using polymer modifiers that are less susceptible to gelling, that provide improved performance, and that retain their good properties over longer periods of time.

Accordingly, provided herein is a polymer-modified asphalt composition as defined in claim <NUM> appended hereto.

Finally, a road pavement or roofing material comprising the polymer-modified asphalt composition is provided.

In a second aspect there is provided a method for preparing the modified asphalt composition as defined in claim <NUM>.

Further, unless expressly stated to the contrary, the term "or" as used herein refers to an "inclusive or" and not to an "exclusive or. " For example, a condition "A or B" is satisfied by any one of the following: A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); and both A and B are true (or present). As used herein, the terms "a" and "an" include the concepts of "at least one" and "one or more than one". The word(s) following the verb "is" can be a definition of the subject.

The term "consisting essentially of" used in relation to compositions indicates that substantially (greater than <NUM> weight % or greater than <NUM> weight %) the only polymer(s) present in a composition is the polymer(s) recited. Thus, this term does not exclude the presence of impurities or additives, e.g. conventional additives. Moreover, such additives may possibly be added via a master batch that may include other polymers as carriers, so that minor amounts (less than <NUM> weight % or less than <NUM> weight %) of polymers other than those recited may be present. Any such minor amounts of these materials do not change the basic and novel characteristics of the composition.

As used herein, the term "about" means that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art. In general, an amount, size, formulation, parameter or other quantity or characteristic is "about" or "approximate" whether or not expressly stated to be such.

Unless stated otherwise, all percentages, parts, ratios, etc., are by weight.

Further, when an amount, concentration, or other value or parameter is given as either a range, preferred range or a list of upper preferable values and lower preferable values, this is to be understood as specifically disclosing all ranges formed from any pair of any upper range limit or preferred value and any lower range limit or preferred value, regardless of whether ranges are separately disclosed. Where a range of numerical values is recited herein, unless otherwise stated, the range is intended to include the endpoints thereof, and all integers and fractions within the range. It is not intended that the scope of the invention be limited to the specific values recited when defining a range. When a component is indicated as present in a range starting from <NUM>, such component is an optional component (i.e., it may or may not be present). When present, an optional component may be present at a level of at least <NUM> weight % of the composition or copolymer, unless present at specified lower amounts. Finally, when the term "about" is used in describing a value or an end-point of a range, the disclosure should be understood to include the specific value or end-point referred to.

When materials, methods, or machinery are described herein with the term "known to those of skill in the art", "conventional" or a synonymous word or phrase, the term signifies that materials, methods, and machinery that are conventional at the time of filing the present application are encompassed by this description. Also encompassed are materials, methods, and machinery that are not presently conventional, but that may have become recognized in the art as suitable for a similar purpose.

As used herein, the term "copolymer" refers to polymers comprising copolymerized units resulting from copolymerization of two or more comonomers. In this connection, a copolymer may be described herein with reference to its constituent comonomers or to the amounts of its constituent comonomers, for example "a copolymer comprising ethylene and <NUM> weight % of acrylic acid", or a similar description. Such a description may be considered informal in that it does not refer to the comonomers as copolymerized units; in that it does not include a conventional nomenclature for the copolymer, for example International Union of Pure and Applied Chemistry (IUPAC) nomenclature; in that it does not use product-by-process terminology; or for another reason. As used herein, however, a description of a copolymer with reference to its constituent comonomers or to the amounts of its constituent comonomers means that the copolymer contains copolymerized units (in the specified amounts when specified) of the specified comonomers. It follows as a corollary that a copolymer is not the product of a reaction mixture containing given comonomers in given amounts, unless expressly stated in limited circumstances to be such.

Polymers having more than two types of monomers, such as terpolymers, are also included within the term "copolymer" as used herein. A dipolymer consists essentially of two copolymerized comonomers and a terpolymer consists essentially of three copolymerized comonomers. The term "consisting essentially of" in reference to copolymerized comonomers allows for the presence of minor amounts (i.e. no more than <NUM> weight %) of non-recited copolymerized units, for example arising from impurities present in the commoner feedstock or from decomposition of comonomers during polymerization.

The term "(meth)acrylate" as used herein refers to methacrylate or acrylate. For example, the term "alkyl (meth)acrylate" refers to alkyl acrylate or alkyl methacrylate.

Moreover, the amounts of all components in a polymer or composition are complementary, that is, the sum of the amounts of all the components is the amount of the entire polymer or composition. For example, when an ethylene copolymer is described by specifying the weight percentage of a copolymerized comonomer, the total of the weight percentages of the copolymerized ethylene, the copolymerized comonomer, and the other copolymerized comonomers, if any, is <NUM> wt%.

The terms "melt flow index" (MFI) and "melt index" (MI) refer to the viscosity of a polymer, as determined by ASTM D <NUM>-65T, Condition E. Melt flow index, reported in units of weight per time, is an indicator of the ability of a polymer to flow under defined conditions of temperature and pressure.

The terms "asphalt" and "bitumen" are synonymous and used interchangeably herein to refer to the naturally-derived component of viscous compositions used for paving and roofing applications. "Bitumen" typically refers to the primarily hydrocarbon base material that is mixed with other components. "Asphalt" may refer to the base material and may also be used to refer to the final composition, including additives and aggregates, as described below. The term "polymer-modified asphalt" and its acronym PMA refer to a polymer-modified composition comprising bitumen or asphalt and to a polymer modified composition that comprises bitumen or asphalt and that is cross-linked.

Finally, the term "gel" and related terms, such as "gelling", as used herein, refer to unprocessible polymer, more specifically a gelatinous semisolid that renders the composition unsuitable for paving. Gelling may be the result of polymer/polymer cross-linking instead of a polymer/asphalt reaction.

Provided herein is a polymer-modified asphalt composition (PMA) that includes a high melt-flow epoxide-containing polymer. These polymers react with asphalt to form a PMA that may more specifically be referred to as a polyepoxy-polymer-linked-asphalt composition. The high melt-flow epoxide-containing polymers dissolve in asphalt more readily than expected, based on the solubility of the lower melt-flow epoxide-containing polymers and in light of typical relationships between a polymer's solubility and its molecular weight. Yet, the high melt-flow epoxide-containing polymers provide PMAs with improved properties comparable to those provided by epoxide-containing polymers with lower melt indices. PMAs containing high melt-flow (MI) epoxide-containing polymers can be mixed at lower temperatures, and the mixing will be completed over shorter times, than PMAs containing low-MI epoxide-containing polymers. The lower temperatures required to dissolve and react these high-MI modifiers offer advantages in energy savings and process economy. The high-MI polymers also provide the PMAs with lower viscosity for a given amount of epoxide-containing polymer. Thus, the amount of epoxide-containing polymer may be increased without detracting from the PMA's processibility. Moreover, PMA concentrates including high-MI epoxide-containing polymer may include higher amounts of polymer than is possible with low-MI epoxide-containing polymers. Finally, warm mix asphalts may be modified with high-MI epoxide-containing polymers instead of low molecular weight waxes, thus providing warm mix asphalts with improved properties.

The PMA includes at least one bitumen or asphalt. The bitumen or asphalt base used in the invention comprises one bitumen, or two or more bitumens of different origins. Representative sources for asphalts and bitumens include native rock, lake asphalts, petroleum asphalts, airblown asphalts, cracked or residual asphalts. Bitumens and asphalts may be of natural origin, such as those contained in deposits of natural bitumen, natural asphalt or bituminous sands.

Asphalt is more commonly obtained as a residue in the distillation or refining of petroleum, such as from vacuum tower bottoms (VTB). All types of asphalts and bitumens, including natural and synthetic materials, are suitable for use in the polyepoxy-polymer-linked-asphalt composition described herein. Bitumens may be optionally blown, visbroken or deasphalted. The bitumens may be hard grade or soft grade materials. Different bitumens may be combined with each other to obtain an improved or optimal profile of end-use properties.

Chemically, asphalt is a complex mixture that can be separated into two major fractions of hydrocarbons, asphaltenes and maltenes. The asphaltenes are polycyclic aromatics and most contain polar functionality. One or more of the following functionalities are present: carboxylic acids, amines, sulfides, sulfoxides, sulfones, sulfonic acids, porphyrins, porphyrin derivatives, metalloporphyrins or metalloporphyrin derivatives comprising cations of vanadium, nickel or iron. The maltene phase contains polar aromatics, aromatics, and naphthene. It is generally believed that asphalt is a colloidal dispersion with the asphaltenes dispersed in the maltenes, and that the polar aromatics function as dispersing agents. The asphaltenes are relatively high in molecular weight (about <NUM> daltons), compared with the other components of asphalt. The asphaltenes are amphoteric in nature and form aggregates through self-association that offer some viscoelastic behavior to asphalt. Asphaltenes vary in amount and functionality depending on the crude source from which the asphalt is derived. Specific examples of suitable crude asphalts include Ajax, Marathon, Wyoming Sour, Mayan, Venezuelan, Canadian, Arabian, Trinidad Lake, Salamanca and combinations of two or more thereof.

All asphalts containing asphaltenes are suitable for use in the polyepoxy-polymer-linked-asphalt composition described herein. The asphalt can be of low or high asphaltene content. Suitable asphaltene concentrations range from about <NUM> to about <NUM>, about <NUM> to about <NUM>, about <NUM> to about <NUM>, or about <NUM> to about <NUM>%, by weight based on the total weight of the asphalt. Suitable low asphaltene concentrations range from about <NUM> to about <NUM> weight %, based on the total weight of the asphalt, such that the asphalt can react with the ethylene copolymer but may not react under heating or with acids such as SPA catalyst (see, e.g., <CIT>). This choice of co-reactant chemistry is believed to accelerate the reaction between the correct asphalt component and the epoxide-functionalized ethylene copolymer. Suitable high asphaltene asphalts contain more than <NUM> weight % asphaltenes or more than <NUM> weight % asphaltenes, based on the total weight of the asphalt. Generally, the asphalts useful in this invention will contain less than <NUM> weight % oxygen compounds and frequently less than <NUM> weight % oxygen compounds, again based on the total weight of the asphalt.

Suitable bitumens are advantageously chosen from road-surface bitumens of classes <NUM>/<NUM> to <NUM>/<NUM> and special bitumens of all classes.

Preferably, the bitumen base is present in the PMA at a level of between about <NUM> and <NUM>% by weight, more preferably between <NUM> or <NUM>% and <NUM>% by weight, based on the total weight of the polymer/bitumen mixture.

Preferred asphalts have a viscosity at <NUM> of <NUM> to <NUM>,<NUM> centipoise, preferably <NUM> to <NUM>,<NUM> centipoise, as measured using the method of AASHTO T316.

Suitable asphalts may also comprise one or more of a sulfonated asphalt, a salt of a sulfonated asphalt (e.g., sodium salt), and an oxidized asphalt. These functionalized asphalts may be present alone or in combination with one or more of the above-described asphalts that are as-isolated from nature.

The polymer-modified asphalt composition further comprises at least one epoxy-functionalized ethylene copolymer. Suitable copolymers include an E/X/Y/Z epoxy-functionalized ethylene copolymer, wherein E represents copolymerized repeat units -(CH<NUM>CH<NUM>)- derived from ethylene; X represents copolymerized repeat units -(CH<NUM>CR<NUM>R<NUM>)-, wherein R<NUM> is a hydrogen atom or a methyl or ethyl group, and R<NUM> is a carboalkoxy, acyloxy, or alkoxy group of <NUM> to <NUM> carbon atoms; Y represents copolymerized repeat units -(CH<NUM>CR<NUM>R<NUM>)-, wherein R<NUM> is a hydrogen atom or a methyl group and R<NUM> is a carboglycidoxy or glycidoxy group; and Z represents copolymerized repeat units derived from one or more additional comonomers.

More specifically, X is derived from copolymerized alkyl acrylates, alkyl methacrylates, vinyl esters, and alkyl vinyl ethers, for example, and the amount of X ranges from <NUM> to <NUM> weight %, based on the total weight of the epoxy-functionalized ethylene copolymer. Y is derived from glycidyl acrylate, glycidyl methacrylate, or glycidyl vinyl ether, for example, and the amount of Y ranges from <NUM> to <NUM> weight %, based on the total weight of the epoxy-functionalized ethylene copolymer. Finally, the optional additional comonomers Z include, without limitation, carbon monoxide, sulfur dioxide, acrylonitrile, and other monomers known to be capable of copolymerization with ethylene. The amount of Z ranges from <NUM> to <NUM> weight %, based on the total weight of the epoxy-functionalized ethylene copolymer. Complementarily, the remainder of the epoxy-functionalized ethylene copolymer consists of copolymerized repeat units -(CH<NUM>CH<NUM>)-derived from ethylene.

Preferably, the epoxy-functionalized ethylene copolymer is a glycidyl-containing polymer. Suitable glycidyl-containing ethylene copolymers and modified copolymers are well known in the polymer art and can readily be produced by the procedures described in <CIT>, for example.

The glycidyl moiety may be represented by the following formula:
<CHM>.

The glycidyl-containing ethylene copolymer comprises, consists essentially of, or consists of repeat units derived from ethylene (E); zero, one or both of the optional comonomers described herein (X and Z); and an epoxy comonomer (Y). Suitable epoxy comonomers include, without limitation, glycidyl esters of acrylic acid or methacrylic acid, glycidyl vinyl ether, and combinations thereof. The epoxy comonomer may be incorporated into the glycidyl-containing ethylene copolymer at a level of from about <NUM> or about <NUM> weight % to about <NUM>, <NUM>, <NUM>, or <NUM> weight %, based on the total weight of the epoxy-functionalized ethylene copolymer. Preferred epoxy comonomers include glycidyl acrylate, glycidyl methacrylate, glycidyl butyl acrylate, glycidyl vinyl ether, for example, and combinations of two or more thereof.

Preferred epoxy-functionalized ethylene copolymers useful in this invention may be represented by the formula: E/X/Y, where E is the copolymer unit -(CH<NUM>CH<NUM>)- derived from ethylene; X is the copolymer unit -(CH<NUM>CR<NUM>R<NUM>)-, where R<NUM> is hydrogen, methyl, or ethyl, and R<NUM> is carboalkoxy, acyloxy, or alkoxy of <NUM> to <NUM> carbon atoms (X for example is derived from alkyl acrylates, alkyl methacrylates, vinyl esters, and alkyl vinyl ethers); and Y is the copolymer unit -(CH<NUM>CR<NUM>R<NUM>)-, where R<NUM> is hydrogen or methyl and R<NUM> is carboglycidoxy or glycidoxy (Y for example is derived from glycidyl acrylate or glycidyl methacrylate). For purposes of this invention the epoxy-containing comonomer unit, Y, may also be derived from vinyl ethers of <NUM> to <NUM> carbon atoms (e.g., glycidyl vinyl ether) or mono-epoxy substituted di-olefins of <NUM> to <NUM> carbon atoms. The R<NUM> in the above formula includes an internal glycidyl moiety associated with a cycloalkyl monoxide structure; e.g., Y is derived from vinyl cyclohexane monoxide. Here, the amount of Z in the copolymer is <NUM> weight %.

In this preferred embodiment, useful weight percentages (based on total weight of E, X, and Y in the copolymer) of the E/X/Y epoxy-functionalized ethylene copolymer units preferably are about <NUM> to about <NUM> weight % of X, about <NUM> to <NUM> weight % of Y, and the remainder a complementary amount of E. Preferably, Y is selected from glycidyl acrylate or glycidyl methacrylate, more preferably glycidyl methacrylate.

Nevertheless, other suitable E/X/Y copolymers contain from <NUM> to about <NUM> weight % of comonomers Y containing glycidyl acrylate or glycidyl methacrylate, such as <NUM> to <NUM> weight %, or <NUM> to <NUM> weight %. Similar copolymers are described in greater detail in co-pending <CIT> (Attorney Docket No. PP0328).

In preferred E/X/Y terpolymers, X is derived from an ester of unsaturated carboxylic acid such as (meth)acrylate or C<NUM> to C<NUM> alkyl (meth)acrylate, or combinations of two or more of these esters. More preferred alkyl (meth)acrylates include iso-butyl acrylate, n-butyl acrylate, iso-octyl acrylate, methyl acrylate and methyl methacrylate.

Notable E/X/Y terpolymers comprise copolymerized units of ethylene, n-butyl acrylate and glycidyl methacrylate (an ENBAGMA copolymer) or copolymerized units of ethylene, methyl acrylate and glycidyl methacrylate (an EMAGMA copolymer).

The epoxy-functionalized ethylene copolymer may optionally include repeat units X derived from a C<NUM> to C<NUM> carboxylic acid ester of an unsaturated alcohol such as vinyl alcohol. A particularly useful vinyl ester is vinyl acetate. A notable E/X/Y terpolymer comprises copolymerized units of ethylene, vinyl acetate and glycidyl methacrylate (an EVAGMA copolymer).

In addition, E/GMA is a preferred dipolymer comprising repeat units derived from copolymerization of ethylene and glycidyl methacrylate. Here, the amount of X and Z in the copolymer is <NUM> weight %.

Preferably, the epoxy-containing monomers Y are incorporated into the epoxy-functionalized ethylene copolymer by the concurrent reaction of monomers ("direct" or "random" copolymerization), rather than by grafting onto the reactant polymer ("graft" copolymerization).

Also preferably, the epoxy-containing ethylene copolymer has a melt flow index as determined by ASTM D1238-65T, Condition E (<NUM>/<NUM>), of about <NUM> or <NUM> to about <NUM> grams/<NUM> minutes, preferably about <NUM> to about <NUM> grams/<NUM> minutes, or about <NUM> to about <NUM> grams/<NUM> minutes, or about <NUM> or <NUM> to about <NUM> grams/<NUM> minutes, or about <NUM> to about <NUM> grams/<NUM> minutes.

Finally, the polymer-modified asphalt composition comprises about <NUM> to about <NUM> weight %, preferably from about <NUM> to about <NUM> or about <NUM> or about <NUM> weight % of the epoxy-functionalized ethylene copolymer, based on the total weight of the polymer-modified asphalt composition.

The polymer-modified asphalt composition may optionally comprise at least one co-reactant, for example an acid or an anhydride. Anhydrides include both linear and cyclic anhydrides.

Linear anhydrides include those of the formula (RCO)2O wherein R comprises C8-C22 alkyl or alkenyl, such as stearic anhydride.

The cyclic anhydride notably comprises a five-or six-member cyclic anhydride structure. Five-member cyclic anhydrides are preferred. The cyclic anhydride may be monocyclic, the only cyclic structure being the cyclic anhydride moiety. Monocyclic anhydrides include glutaric anhydride, succinic anhydride, maleic anhydride, citraconic anhydride, itaconic anhydride and substituted succinic anhydrides such as methyl succinic anhydride, phenyl succinic anhydride, butyl succinic anhydride, <NUM> octen-<NUM>-yl succinic anhydride, dodecenyl succinic anhydride and hexadecyl succinic anhydride. Preferred monocyclic anhydrides include maleic anhydride and substituted succinic anhydrides such as dodecenyl succinic anhydride.

The cyclic anhydride may also be multicyclic, with at least one ring in addition to the cyclic anhydride moiety. The multicyclic anhydride may be aliphatic or aromatic. Aliphatic multicyclic anhydrides include tetrahydrophthalic anhydride, cyclohexane dicarboxylic anhydride and methyl nadic anhydride, preferably cyclohexane dicarboxylic anhydride. Aromatic anhydrides include phthalic anhydride, homophthalic anhydride, pyromellitic dianhydride, trimellitic anhydride, mellitic anhydride, <NUM>,<NUM>-naphthoic anhydride and <NUM>,<NUM>-naphthoic anhydride, preferably phthalic anhydride, pyromellitic dianhydride and trimellitic anhydride.

Finally, the polyepoxy-polymer-linked-asphalt composition comprises about <NUM> to about <NUM> weight %, preferably from about <NUM> to about <NUM> weight % of the anhydride, when present, based on the total weight of the polyepoxy-polymer-linked-asphalt composition.

The polymer-modified asphalt composition may optionally include at least one acid co-reactant. Inorganic acids and organic acids are suitable, for example mineral acids, phosphorous acid, phosphoric acids, sulfonic acids, carboxylic acids, and combinations of two or more of these acids. Examples of frequently used acids include polyphosphoric acid and superphosphoric acid. The polymer-modified asphalt composition can comprise from a lower limit of about <NUM>, about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> weight % to an upper limit of about <NUM>, about <NUM>, or about <NUM> weight % of the acid(s), based on the total weight of the polymer-modified asphalt composition.

Notably, the polymer-modified asphalt composition may comprise phosphorous acid to provide an asphalt composition with improved properties. Phosphorous acid has the empirical formula H<NUM>PO<NUM> and the structural formula HP(O)(OH)<NUM>. This species exists in equilibrium with a minor amount of tautomer, P(OH)<NUM>. IUPAC recommendations from <NUM> are that the latter be called phosphorous acid, whereas the dihydroxy form is called phosphonic acid. As used herein, however, the term "phosphorous acid" refers to both tautomers and any mixture of the two tautomers, unless stated otherwise in limited circumstances. Phosphorous acid is a diprotic acid, since the hydrogen bonded directly to the central phosphorus atom is not readily ionizable. The pKa for the first deprotonation is <NUM>, and the pKa for the second deprotonation is <NUM>. Phosphorous acid is a white crystalline material that melts at <NUM> to <NUM>. This makes phosphorous acid significantly easier to handle, transport and mix with asphalt compared to polyphosphoric acid (PPA), which is a liquid at room temperature.

Both phosphorous acid and its deprotonated forms are good reducing agents, although not necessarily quick to react. This reducing behavior may decrease deterioration or "aging" of asphalt, which is evident in failure modes such as brittleness, rutting, fatigue or cold temperature cracking. Without wishing to be held to theory, it is hypothesized that asphalt modified with nonreducing acids such as PPA will be more susceptible to deterioration that is caused in part by oxygen penetration and oxidation of the asphalt components.

When present, the phosphorous acid is included in the asphalt composition at a level of about <NUM> to about <NUM> weight%, based on the total weight of the polymer-modified asphalt composition, such as from about <NUM> or about <NUM> weight %, to about <NUM> weight % or about <NUM> weight %.

See co-pending <CIT> and <CIT> (Attorney Docket Nos. PP0352 USPSP and PP0352 USPSP2) for further discussion of the use of acid co-reactants in PMAs.

Non-reactive polymers are polymeric compositions that are known in the art for inclusion in polymer-modified asphalt and that do not react with the asphalt. They may be used together with phosphorous acid to modify asphalt in the absence of a reactive polymer such as the epoxy-containing polymers described above. Optionally, non-reactive or "diluent" polymers may be further included in the polyepoxy-polymer-linked-asphalt composition described above, in combination with phosphorous acid. Preferably, these non-reactive polymers are also non-reactive towards the epoxy-functionalized ethylene copolymers and the functionalized polyolefins.

Suitable non-reactive polymers include, without limitation, ethylene alkyl acrylate, ethylene alkyl methacrylate or ethylene vinyl acetate copolymers, styrene/conjugated-diene block copolymers including styrene polybutadiene or isoprene, ethylene butene block copolymers (e.g., SBS, SIS, and SEBS block copolymers), polyolefins produced by any process known in the art with any known transition metal catalyst or single-site catalyst, or combinations thereof. More specifically, the non-reactive polymers include olefinic polymers such as polyethylene, polypropylene, polybutene, polyisobutene, ethylene/propylene copolymers, ethylene/propylene/diene terpolymers, or polymers such as polybutadiene, polyisoprene or polynorbornene.

These non-reactive polymers can be combined with phosphorous acid to modify asphalt in amounts that range from a lower limit of <NUM> or <NUM> to an upper limit of <NUM>, <NUM>, <NUM> or <NUM> weight %, based on the total weight of the polymer-linked-asphalt composition.

Moreover, the non-reactive polymers can be combined into the reactive asphalt, reactive epoxy-functionalized ethylene copolymers and reactive functionalized polymers in amounts that range from <NUM> to <NUM> weight %, or <NUM> to <NUM> weight %, or <NUM> to <NUM> weight %, or <NUM> to <NUM> weight %, based on the total weight of the polymer-modified asphalt composition. When present, the non-reactive polymer may be included from a lower limit of <NUM> or <NUM> to an upper limit of <NUM>, <NUM>, <NUM>, or <NUM> weight %, based on the total weight of the PMA composition.

Preferred nonreactive polymers include styrene/conjugated-diene block copolymers. The styrene/conjugated-diene block copolymers useful in this invention are well-known polymers derived from, or comprising, styrene and a conjugated-diene, such as butadiene, isoprene, ethylene butene, <NUM>,<NUM>-pentadiene and the like. For simplicity, the term "styrene-butadiene-styrene" block copolymer, or "SBS" copolymer, unless specified more narrowly, will be used herein to refer to any such polymers of styrene and a conjugated diene.

The styrene/conjugated-diene block copolymers may be di-, tri- or poly-block copolymers having a linear or radial (star or branched) structure, with or without a random junction. Suitable block copolymers include, for example, diblock A-B type copolymers; linear (triblock) A-B-A type copolymers; and radial (A-B)n type copolymers; wherein A refers to a copolymer unit derived from styrene and B refers to a copolymer unit derived from a conjugated-diene. Preferred block copolymers have a linear (triblock) A-B-A type structure or a radial (A-B)n type structure.

Generally, the styrene/conjugated-diene block copolymer will contain about <NUM> to about <NUM> weight % of copolymer units derived from styrene and about <NUM> to about <NUM> weight % of copolymer units derived from a conjugated diene, preferably butadiene or isoprene, more preferably butadiene. More preferably, <NUM> to <NUM> weight % of the copolymer units will be derived from styrene, the remainder being derived from the conjugated-diene.

Preferably, the styrene/conjugated-diene block copolymers have a weight-average molecular weight from a lower limit of about <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM>, <NUM>,<NUM> or <NUM>,<NUM> daltons to a higher limit of about <NUM>,<NUM>, <NUM>,<NUM>, <NUM>, <NUM> or <NUM>,<NUM>,<NUM> daltons. The weight-average molecular weight of the styrene/conjugated-diene block copolymer can be determined using conventional gel permeation chromatography.

The melt flow index of the styrene/conjugated-diene block copolymer will typically be in the range from about <NUM> to about <NUM>/<NUM>, preferably about <NUM> to <NUM>/<NUM>, more preferably about <NUM> to <NUM>/<NUM>, as determined by ASTM Test Method D <NUM>, Condition G.

Notable SBS copolymers have an overall content of <NUM> to <NUM> % by weight of butadiene and the content of units containing a <NUM>,<NUM> double bond resulting from butadiene of <NUM> to <NUM> weight % of the copolymer. The weight-average molecular mass of the copolymer of styrene and of butadiene can be between <NUM>,<NUM> and <NUM>,<NUM> daltons, preferably between <NUM>,<NUM> and <NUM>,<NUM> daltons.

The copolymers of styrene and conjugated-diene can be prepared by anionic polymerization of the monomers in the presence of initiators composed of organometallic compounds of alkali metals, in particular organolithium compounds, such as alkyllithium and preferably butyllithium, the preparation being carried out at temperatures of less than or equal to <NUM> and in solution in a solvent that is at least partly composed of a polar solvent, such as tetrahydrofuran or diethyl ether. Preparation procedures include those described in <CIT> and <CIT>.

Suitable styrene/conjugated-diene block copolymers are commercially available, for example, under the tradenames KRATON™, EUROPRENE SOL™ and SOLPRENE™ from Shell Chemical Company, Enichem and Phillips Petroleum Company, respectively.

Specific SBS copolymers include a block copolymer with a weight-average molecular mass of <NUM>,<NUM> daltons and containing, by weight, <NUM>% of copolymerized styrene and <NUM>% of copolymerized butadiene, including an amount of units containing a <NUM>,<NUM> double bond representing <NUM>% of the copolymer;.

The styrene polybutadiene or isoprene, ethylene butene block copolymers (e.g., SBS, SIS, SEBS block copolymers) can be combined with phosphorous acid to modify asphalt in an amount ranging from a lower limit of <NUM> or <NUM> to an upper limit of <NUM>, <NUM>, <NUM> or <NUM> weight %, based on the total weight of the polymer-linked-asphalt composition.

Notable polymer-modified asphalt compositions comprise an epoxy-containing polymer and <NUM> weight % of styrene polybutadiene or isoprene, ethylene butene block copolymers (e.g., SBS, SIS, SEBS block copolymers). Alternatively, the epoxy-containing polymer, styrene polybutadiene or isoprene, ethylene butene block copolymer (e.g., SBS, SIS, SEBS block copolymer), and phosphorous acid can be incorporated into asphalt to provide a PMA. When present in the PMA, the amount of the styrene block copolymers ranges from a lower limit of <NUM> or <NUM> to an upper limit of <NUM>, <NUM>, <NUM>, or <NUM> weight %, based on the total weight of the polymer-modified asphalt composition.

The polyepoxy-modified asphalt composition may optionally comprise one or more of a flux oil, a liquid plasticizer, a sulfur source and a hydrogen sulfide scavenger.

Flux oils encompass many types of oils used to modify asphalt and are the final products in crude oil distillation. They are non-volatile oils that are blended with asphalt to soften it. For example, flux oils may be petroleum-based products. They can be aromatic, such as ValAro from Paulsboro Refining Company, Paulsboro NJ; paraffinic, such as Hydrolene™ from HollyFrontier Refining & Marketting LLC, Plymouth Meeting PA; or mineral such as Hydrobryite™ from Sonneborn, LLC, Parsippany, NJ. Flux oils can also be a shortening or any renewably-produced vegetable or bio-oil. Blends of two or more such oils are also contemplated.

A liquid plasticizer is an additive that increases the plasticity or fluidity of a material. The major applications are for plastics, such as phthalate esters for improving the flexibility and durability of polymer compositions. Examples of suitable liquid plasticizers include, without limitation, carboxylate esters, for example any dicarboxylic or tricarboxylic ester-based plasticizers, such as bis(<NUM>-ethylhexyl) phthalate (DEHP), di-octyl phthalate (DOP), diisononyl phthalate (DINP), and diisodecyl phthalate (DIDP). Suitable liquid plasticizers also include acetic acid esters of monoglycerides made from castor oil; and other nonphthalate plasticizers for PVC including trimellitates, such as tris(<NUM>-ethylhexyl) trimellitate, adipates such as bis(<NUM>-ethylhexyl) adipate, benzoates such as <NUM>,<NUM>-pentanediol dibenzoate, adipic acid polyesters, polyetheresters, and epoxy esters or maleates.

Suitable levels of these materials and methods of incorporating them into the asphalt composition are described in detail in Intl. Patent Appln. No. <CIT> (Attorney Docket No. PP0325). Briefly, however, the ratio of ethylene copolymer to flux oil or a liquid plasticizer ranges from <NUM>:<NUM> to <NUM>:<NUM>, by weight based on the total weight of the ethylene copolymer and the flux oil or liquid plasticizer. In addition, when the flux oil or liquid plasticizer is present, its level is preferably about <NUM> to about <NUM> weight %, based on the total weight of the based on the total weight of the asphalt composition.

A hydrogen sulfide scavenger is an agent capable of neutralizing hydrogen sulfide (H<NUM>S). It is a compound or a mixture of compounds which in the presence of H<NUM>S combines with the latter so as to collect or scavenge it, thus reducing or eliminating the emission or the release of H<NUM>S at PMA storage, transfer and transport temperatures. For the sake of simplicity, the word "scavenger" is used in the remainder of the description to refer to the agent capable of reducing H<NUM>S emissions. The use of an H<NUM>S scavenger makes it possible to significantly reduce, or advantageously to eliminate, the release of H<NUM>S during the preparation, loading or unloading of a bitumen/polymer composition. Hydrogen sulfide scavengers include those described in <CIT>, and <CIT>.

The amount of H<NUM>S scavenger depends on the amount of sulfur source(s) present in the asphalt. For example, the H<NUM>S scavenger may be added to the asphalt composition in an amount from a lower limit of about <NUM>, about <NUM>, about <NUM>, about <NUM>, or about <NUM> weight % to an upper limit of about <NUM>, about <NUM>, about <NUM> or about <NUM> weight %, based on the total weight of the PMA. The effective amount may be determined by preparing a sample of a desired asphalt composition and adding sufficient H<NUM>S scavenger to reduce H<NUM>S emissions below a predetermined limit, such as less than <NUM> ppm of asphalt.

The asphalt composition may also include one or more sulfur sources to generate sulfur in the polymer/asphalt blend or in the PMA. Suitable sulfur sources include, without limitation, elemental sulfur, a sulfur donor, or a sulfur byproduct, which are useful as crosslinking agents.

The sulfur cross-linking agent is preferably elemental sulfur, a hydrocarbyl polysulfide, a sulfur-donor vulcanization accelerator, another sulfur source, or a combination of two or more of these sulfur cross-linking agents. The elemental sulfur is preferably flowers of sulfur and, more preferably, crystallized sulfur in orthorhombic form, also known as alpha sulfur. Suitable sulfur-donor vulcanization accelerators include, without limitation, mercaptobenzothiazole (MBT), the thiurams, thiuram polysulfides, alkylphenol disulfides, disulfides, dithiocarbamates and their derivatives. Other suitable sulfur sources include, without limitation sodium diethyldithiocarbamate, <NUM>,<NUM>-dithiobis(benzothiazole), mercaptobenzothiazole, dipentamethylenethiuram tetrasulfide, and Sasobit® TXS (a proprietary product available from Sasol Wax Americas, Shelton, CN, USA). Suitable hydrocarbyl polysulfides, sulfur-donor vulcanization accelerators, and other sulfur sources are described in French Patent Application <CIT> and in the references cited therein.

The cross-linking of the bitumen/polymer mixture is carried out under stirring, by heating at a temperature between <NUM> and <NUM>, for at least <NUM> minutes. The amount of sulfur-containing cross-linking agent is preferably from <NUM>% to <NUM>% by weight, more preferably from <NUM> and <NUM>% by weight, based on the total weight of the PMA and complementarily with the other components of the PMA. Alternatively, the sulfur source(s) may be added to the asphalt in a step that is separate from the step(s) of adding the ethylene copolymer and the acid or anhydride, if present. For example, the ethylene copolymer, sulfur source and H<NUM>S scavenger can be added to asphalt, mixed for a brief period of time, and then the acid can be added with further mixing to produce the PMA.

Further provided herein is a method of preparing a polymer-modified asphalt composition. This method comprises the steps of:.

Examples of suitable processes for blending epoxy-functionalized polymers with asphalt include those in which the epoxy-functionalized ethylene copolymer comprises an ethylene vinyl acetate glycidyl methacrylate terpolymer, an ethylene n-butyl acrylate glycidyl methacrylate terpolymer or an ethylene methyl acrylate glycidyl methacrylate terpolymer.

Further examples of suitable processes include those in which step (<NUM>) comprises.

Examples of suitable processes also include those in which step (<NUM>) comprises adding the acid or anhydride to the heated asphalt in the reactor with stirring for about <NUM> or <NUM> minutes to about <NUM> to <NUM> hours, while maintaining the temperature of the asphalt at <NUM> to <NUM>.

PMAs have been typically produced in a high-shear mill process, or a low-shear mixing process, as is well known to one skilled in the art. For example, the process is dependent on the equipment available, and on the polymers used. In general, polymers that can be used in low-shear mixing equipment can also be used in high-shear equipment. A molten mixture of asphalt and polymer modifiers can be heated at about <NUM> to about <NUM>, or about <NUM> to <NUM>. The molten mixture can be mixed by a mechanical agitator, for example, or by any other suitable mixing means.

Publications IS-<NUM>, from the Asphalt Institute of Lexington, KY, are among the references that describe suitable methods for the commercial production of PMAs.

The base asphalt can be preheated to <NUM> to <NUM> or higher in a blending vessel to make it flowable. The ethylene copolymer and phosphorous acid can be added to asphalt with stirring at temperatures from <NUM> to <NUM>, such as about <NUM> to <NUM>. It is desirable to heat the materials to as low a temperature as necessary while still obtaining good processing rates.

The use of phosphorous acid allows for greater flexibility of preparation of the polymer-modified asphalt composition, compared to PMAs prepared with polyphosphoric acid. In some embodiments, the ethylene copolymer and the phosphorous acid are added to the heated asphalt in separate sequential steps, allowing for mixing the ethylene copolymer with the asphalt prior to adding the phosphorous acid. For example, the copolymer can be mixed with heated asphalt for a period of time such as <NUM> minutes to one hour, or more, followed by the addition of the phosphorous acid with further mixing for a period of time such as <NUM> minutes to one hour, or more.

Alternatively, at least some of the ethylene copolymer can be added to the asphalt after addition of the phosphoric acid, if necessary to adjust the properties of the PMA. It also may be possible to add the ethylene copolymer and the phosphorous acid at nearly the same time, with a very short mixing period to melt the ethylene copolymer pellets. These options may not be feasible when the polymer/asphalt blends include polyphosphoric acid.

The phosphorous acid facilitates blending of the polymer modifier with the asphalt, providing faster mixing times compared to addition of the polymer to the asphalt without the phosphorous acid. For example, improvements in properties such as pass/fail temperature, phase angle and elastic recovery of the polymer modified asphalt composition may be obtained in an hour or less, for example <NUM> or <NUM> minutes after addition of the phosphorous acid. This may be significantly faster than the time to reach complete blending in PMAs containing the polymer alone and may even be faster than the blending time of PMAs that include both polymer and polyphosphoric acid.

In other suitable methods, an epoxy-containing ethylene copolymer (ECP) or a nonreactive polymer such as a SBS polymer can be combined with, or added to, flux oil or a plasticizer as described above by any means known to one skilled in the art to produce a solution or substantially a solution. The polymer modifier(s) and other optional components can be dissolved in the flux oil or liquid plasticizer by mixing with the oil or plasticizer prior to mixing them with the asphalt. To facilitate the formation of a solution, the combination or addition can be mixed by, for example, mechanical means such as stirring. For example, the formation of an ECP solution in oil or plasticizer can be carried out under atmospheric conditions, stirring for <NUM> to <NUM> minutes at <NUM> to <NUM> and <NUM> to <NUM> RPM. The resulting blend, a solution of polymer modifier in oil or plasticizer, has the consistency of free-flowing oil at elevated temperatures. Examples of these processes are described in detail in co-pending <CIT> (Intl. Patent Appln. No. <CIT>; Attorney Docket No. PP0325).

The epoxy-containing ethylene copolymer solution can comprise about <NUM> to about <NUM>, or about <NUM> to about <NUM>, or about <NUM> to about <NUM>, or about <NUM> to about <NUM> wt% of an epoxy-containing ethylene copolymer and complementarily about <NUM> to about <NUM>, or about <NUM> to about <NUM>, or about <NUM> to about <NUM>, or about <NUM> to about <NUM> wt% of the flux oil(s) or liquid plasticizer(s), based on the total weight of the solution.

After its preparation, the epoxy-functionalized ethylene copolymer solution can be mixed with asphalt. Dispersion of the ethylene copolymer solution into the asphalt may take <NUM> to <NUM> minutes, followed by addition of the phosphorous acid with stirring for an additional period of time such as <NUM> to <NUM> minutes. As discussed above, use of phosphorous acid may provide alternative embodiments in which the epoxy-functionalized ethylene copolymer solution is added to the heated asphalt in two or more aliquots before and after addition of the phosphorous acid. Alternatively, the epoxy-functionalized ethylene copolymer solution is added to the asphalt simultaneously with the phosphorous acid.

The polymer-modified asphalt compositions described herein are useful for elastomeric modification of asphalt compositions. Accordingly, the PMAs are suitable for use in asphalt compositions for road pavement or for roofing materials, such as shingles, sheets, or roll products, and in any other application in which an elastomerically modified asphalt composition is useful.

A suitable road-paving material includes about <NUM> to about <NUM> or about <NUM> wt% of the PMA and complementarily about <NUM> to about <NUM> or about <NUM> wt% of aggregates. Polymer-modified asphalt compositions are useful in materials for paving highways, city streets, parking lots, ports, airfields, sidewalks, and the like. Polymer-modified asphalts can also be used as a chip seal, an emulsion, or another repair product for paved surfaces.

The PMAs described herein are also suitable for use as roofing or waterproofing products. For example, the PMAs are suitable for use to adhere various roofing sheets to roofs and for use as waterproofing coatings for many roofing fabrics. Preferably, the PMAs used as roofing or waterproofing products include a relatively high amount of the epoxy-functionalized ethylene copolymer, for example about <NUM> or <NUM> wt%, based on the total weight of the PMA,.

The following examples are provided to describe the invention in further detail. These examples, which set forth specific embodiments and a preferred mode presently contemplated for carrying out the invention, are intended to illustrate and not to limit the invention.

Summarized in Table <NUM> are ethylene copolymers containing glycidyl methacrylate (GMA) and optionally n-butyl acrylate (nBA) or vinyl acetate (VA) comonomers that are useful for blending with bitumens to provide polymer-modified asphalt compositions.

Table <NUM> lists several styrene copolymers available from Kraton Polymers, Inc. (Houston, TX) that are useful for blending with bitumens to provide polymer-modified asphalts.

Other suitable asphalt modifers include:.

Penetration Grade bitumen is commonly used in road surfacing and some industrial applications. A Penetration Test (ASTM D946-<NUM> and EN12591-<NUM>) determines the hardness of bitumen by measuring the depth (in tenths of a mm) to which a standard and a loaded needle will vertically penetrate in <NUM> seconds a sample of Bitumen maintained at a temperature of <NUM> (<NUM>°F). Hence the softer the bitumen, the greater will be its number of penetration units (e.g. <NUM>/<NUM> asphalt is softer than <NUM>/<NUM> asphalt in this classification system). Thus, asphalt samples classified based on their penetration grade were obtained from Valero (San Antonio TX), Marathon Asphalt (Catlettsburg, Kentucky) Litvinov (Czech Republic), Repsol (Spain), Bapco (Qatar), and Rastanura (Saudi Arabia) and are. Although several of the asphalt samples have the same PG values, they are derived from different crude oil sources and exhibit different reactivity. A lot with qualitatively higher reactivity is designated "HR" and a lot with qualitatively lower reactivity is designated "LR".

A standard one-quart can was equipped with a heating mantle was used to for mixing asphalt and modifiers. Its lid was modified to include a center hole of about <NUM> in diameter to accommodate a stirring shaft and second hole of about <NUM> in diameter to accommodate a thermocouple probe. The stirring shaft was threaded through the lid so that the lid could be sealed on the sample can when the stirring shaft and motor are positioned to mix the sample.

Asphalt samples in <NUM>-gallon cans were heated in a ventilated oven set at <NUM> until they were warm enough to be poured into the one-quart can. The asphalt sample (<NUM>) was poured into the blending can and the lid and stirrer assembly were attached. The polymer modifier sample was added and the lid sealed tightly to the can. The asphalt and polymer were mixed for <NUM> to <NUM> minutes at <NUM> to blend them, followed optionally by injection of the acid through a hole in the lid with continued mixing for one additional hour to further blend all ingredients. When the acid was not used, the mixing time was extended to <NUM> to <NUM> hours. Samples were removed and tested as described below.

Dissolution tests were conducted to characterize the ease with which the sample modifiers were dissolved in bitumen. The results are summarized in Table <NUM>. For each run, <NUM> grams of Salamanca <NUM>-S bitumen were heated to the specified temperature with agitation for about <NUM> minutes. Then <NUM>% of the test EVAGMA modifier was added and the mixture was stirred for the specified time. The blend was then poured onto aluminum foil to form a thin layer and observed for any undissolved pellets. The pellets observed in the samples summarized in Table <NUM> were given qualitative ratings according to the listed criteria. They indicate the extent to which the pellets dissolved in the bitumen for the time and temperature indicated.

The results in Table <NUM> show little dissolution of EVAGMA-<NUM> at <NUM> during <NUM> minutes of mixing time. It took at least <NUM> minutes at <NUM> for EVAGMA-<NUM> to fully dissolve. Because there was essentially no dissolution of EVAGMA-<NUM> at <NUM> for short mixing times, its dissolution was not measured at <NUM> and <NUM>. The high MI EVAGMA-<NUM> fully dissolved in <NUM> minutes or less at all temperatures from <NUM> to <NUM>. The lower temperatures required to dissolve and react for these high MI modifiers could offer advantages in energy savings and reduced total time to produce a PMA.

The samples summarized in Tables <NUM>, <NUM>, <NUM> and <NUM> were prepared according to the General Procedure above, except where noted. Samples with a B prefix were the base bitumens without additives.

Samples C4, C5, <NUM>, <NUM>, <NUM>, <NUM>, C6, C7 included no acid and were mixed at <NUM> for <NUM> hours. The properties of the blends were characterized as described below and are summarized in Tables <NUM> and <NUM>.

Dynamic Shear Rheometer failure temperature and phase angle measurements were performed on the PMAs according to the ASSHTO T <NUM> or ASTM D7175-<NUM> methods to determine the Rheological Properties of Asphalt Binder Using a Dynamic Shear Rheometer (DSR). This method, which is used in the Superpave PG asphalt binder specification, characterizes the viscous and elastic behavior of asphalt binders at medium to high temperatures. More specifically, the DSR test method is used to determine the dynamic shear modulus and phase angle of asphalt binders under dynamic or oscillatory shear using parallel plate geometry. The linear viscoelastic properties of the asphalt binders are derived from these values. The results of the DSR measurements are reported below in Table <NUM>. Average values are reported if multiple trials were run on the same material.

The Pass/Fail temperatures are related to the temperature experienced by the pavement in the geographical area for which the asphalt binder is intended to be used. The Pass temperature is the value according to a Superpave classification scale to determine the asphalt performance grade (PG) where each value has a difference of <NUM>, for example, <NUM>, <NUM>, <NUM>, <NUM>, <NUM>, <NUM> or <NUM>, and the Fail temperature is the actual value at which the modified asphalt fails.

The phase angle defines the resistance to shear deformation of the asphalt binder in the linear viscoelastic region. The phase angle may depend upon the magnitude of the shear strain. Phase angle for both unmodified and modified asphalt decreases with increasing shear strain. Desirably, phase angles are below <NUM>° for most asphalt applications.

Elastic recovery was measured in accordance with ASTM D6084. Multiple Stress Creep and Recovery (MSCR) data were measured in accordance with ASTM D7405-10a. Ring and Ball tests were conducted according to ASTM D36/<NUM>-<NUM>, on green material and after a Rolling Thin Film Oven Test ("RTFOT"). In the Ring and Ball test, two horizontal disks of bitumen, cast in shouldered brass rings, are heated at a controlled rate in a liquid bath while each supports a steel ball. The softening point is reported as the mean of the temperatures at which the two disks soften enough to allow each ball, enveloped in bitumen, to fall a distance of <NUM> (<NUM> inch). Viscosity was measured using a Brookfield Rotational Viscometer according to ASTM D7741.

Examples <NUM>-<NUM> demonstrate the use of the high-MI modifiers for preparing high modifier concentrates at concentrations of <NUM> to <NUM> weight % that can be further mixed with additional asphalt. A low-MI modifier at <NUM> weight % provides an asphalt concentrate that is too viscous to be useful. Examples <NUM> and <NUM> demonstrate the use of high-MI modifiers for warm mix asphalt. Examples <NUM> and <NUM> demonstrate the use of the high-MI modifiers as potential warm mix asphalt candidates. They provide superior elasticity compared to Honeywell Titan™ wax, which is used to prepare Warm Mix PMA's. The high-MI polymer modifier provides low viscosity and a much higher degree of elasticity than wax modified asphalt, as measured by elastic recovery. In addition, the high-MI modifiers did not adversely affect low temperature properties (Bending Beam Rheometer, BBR), in contrast to the waxes. Additional examples of high-MI polymer modified asphalt are summarized in Table <NUM>, and their properties are reported in Table <NUM>. The asphalt used in Examples B7, C13, and <NUM> to <NUM> is believed to originate in Australia.

A significant reduction (<NUM>% - <NUM>%) in the viscosity of the SBS blends was observed when the epoxy-functionalized ethylene copolymer had a high melt index, compared to blends with epoxy-functionalized ethylene copolymers having a standard melt index. Surprisingly, differences in PG Pass/Fail temperature were about <NUM> to <NUM>, which is less than one Performance Grade (<NUM>). Utilizing high-MI epoxy-functionalized ethylene copolymer vs. standard MI epoxy-functionalized ethylene copolymer allows a higher concentration of epoxy-functionalized ethylene copolymer in the SBS blends, as evidenced by reduced gelation at similar polymer weight ratios.

Several PMAs were subjected to the cigar tube separation test (CTST; ASTM D5892-96A). An aluminum tube (<NUM> in in length with a diameter of <NUM> in) was filled with the PMA, sealed, and aged in an oven for <NUM> hours at <NUM>. The tube was then quench-cooled in a freezer at -<NUM>. The frozen specimen was cut into two pieces (top and bottom) and a Ring and Ball test was conducted on each piece at <NUM>. No difference or a minimal difference in Ring and Ball results between the top and bottom pieces shows that little or no separation has occurred upon heat-aging the PMA. The results of these experiments are set forth in Table <NUM>.

Claim 1:
A polymer-modified asphalt composition comprising:
(a) <NUM> to <NUM> weight % of an asphalt;
(b) <NUM> to <NUM> weight % of an E/X/Y/Z epoxy-functionalized ethylene copolymer, wherein E is the copolymerized repeat unit -(CH<NUM>CH<NUM>)- derived from ethylene; X is the copolymerized repeat unit - (CH<NUM>CR<NUM>R<NUM>)-, wherein R<NUM> is a hydrogen atom, a methyl group, or an ethyl group, and R<NUM> is a carboalkoxy, acyloxy, or alkoxy group comprising <NUM> to <NUM> carbon atoms; Y is the copolymerized repeat unit -(CH<NUM>CR<NUM>R<NUM>)-, wherein R<NUM> is hydrogen or methyl and R<NUM> is carboglycidoxy or glycidoxy; and Z is a copolymerized repeat unit derived from one or more comonomers selected from the group consisting of carbon monoxide, sulfur dioxide, and acrylonitrile; wherein the E/X/Y/Z epoxy-functionalized ethylene copolymer comprises <NUM> to <NUM> wt% of X, <NUM> to <NUM> wt% of Y, and <NUM> to <NUM> wt% of Z; wherein the weight percentages of the copolymerized repeat units E, X, Y and Z are complementary and based on the total weight of the E/X/Y/Z epoxy-functionalized ethylene copolymer; and wherein the E/X/Y/Z epoxy-functionalized ethylene copolymer has a melt flow index of from <NUM> to <NUM>/<NUM>, measured according to ASTM D1238-65T, Condition E, at <NUM> and under a load of <NUM>; and, optionally,
(c) <NUM> to <NUM> weight% of a co-reactant, wherein the co-reactant comprises one or more materials selected from the group consisting of polyphosphoric acid, phosphorous acid, and trimellitic anhydride;
wherein the weight percentages of the asphalt, the E/X/Y/Z epoxy-functionalized ethylene copolymer, and the co-reactant are complementary and based on the total weight of the asphalt, the E/X/Y/Z epoxy-functionalized ethylene copolymer, and the co-reactant.