13

. . The invention relates to the reaction of asphalt and

₁₅ polymers to produce an improved polymer-linked-asphalt _lg product. More particularly, the present invention

₁₇ relates to the reaction and resultant linking of

₁₈ epoxide-containing polymers to asphalt forming a _i g polyepoxy polymer-linked-asphalt composition having ₂₀ unique properties. The improved polymer-linked-asphalt _. product is particularly useful in road paving and roofing applications.

23

24 2. Publications: 25 26 The use of polymers as additives to asphalt (bitumen) is 27 well-known in the art. See for example U.S. Patents 4,650,820 and 4,451,598 wherein terpolymers derived from 28 ethylene, an alkyl acrylate and maleic anhydride are 29 mixed with bitumen. 30 31

_- Also disclosed in a trade brochure by ORKEM is the use ₃ _ of terpolymers prepared from ethylene, an alkyl acrylate

34

1 and either maleic anhydride or glycidyl methacrylate as 2 enhancement additives for bitumen and tar. 3 ₄ U.S. Patent 3,324,041 describes a polyepoxide-containing ₅ asphalt emulsion in which a polyamide/bituminous

₀ g emulsion is mixed with a polyepoxide/nonionic-surfactant

₀₇ emulsion to form a composition which is subsequently

08 solidified by the interaction of the polyamide and the 09 polyepoxide. Separately, the two emulsions are stable 10 for a long time. But, when they are mixed the final .- emulsion has a pot life of approximately 16 hours at ~2 21 ^β C. It is necessary to store each of the emulsions

₁₃ independently and only mix them a short time before use.

₁₄ Epoxidized polymers and copolymers derived from

₁₅ diolefins are disclosed.

16

₁₇ Australian Patent Application 88307743 teaches a storage

₁₈ stable and creep resistant asphalt paving binder _lg prepared from an asphalt having about 7 weight percent

₂₀ or less asphaltenes, and a copolymer derived from

₂₁ ethylene and at least one compound selected from the

22 group of vinyl acetate, alkyl acrylate or

₂₃ methylacrylate. The patent teaches that the particular

24 conditions at which the asphalt is blended with the

₂₅ polymer are not critical. Unfortunately, few asphalts

26 have less than 7% asphaltenes, and so this modified asphalt composition is of limited use. 27 28 29 U.S. Patent 4,839,404 discloses ethylene acrylic acid 30 copolymers and the salts thereof as useful in paving and

₃₁ other types of asphalt. This patent discloses that

32 improved adhesion of aggregate and bitumen can be ₃₃ achieved by incorporating small amounts of certain

34 α-olefin/carboxylic acid copolymers into the mixture.

01 The preferred composition is further characterized as 02 one being substantially free of α-olefin/ester _Q 2 copolymers.

04

05 British Patent Application 2,022,597 discloses grafting 06 unsaturated reactants, such as esters of unsaturated 07 acids, including glycidyl acrylate and methacrylate onto 08 ethylene copolymers. These graft copolymers are taught 09 to have many uses including uses in various adhesive 10 compositions, such as: sealing mastics, coating .. compositions, tackifying resins, waxes, plasticizers, - ₂ bitumen, asphalts, tars, diluting polymers, fillers, ₁₃ stabilizing agents, etc.

14

₁₅ Even though polymer-modified asphalts are known, there

₁₆ still exists a need in the asphalt industry for improved -_ asphalts. In part, this is because currently known _lfl polymer-modified asphalts have a number of deficiencies.

19 These deficiencies include susceptibility to flexural 20 fatigue, permanent deformation (rutting), moisture

₂₁ damage (stripping), and low temperature thermally-

__ induced cracking.

23

₂ . Another problem with prior polymer-modified asphalts is

._ poor storage stability and poor homogeneity of the _.. polymer with the asphalt. Poor storage stability is evidenced by viscosity increase in storage and product

27 gelation while poor homogeneity is evidenced by phase 28 separation. Also, new performance criteria are contin¬ 29 ually being developed by various highway governmental 30 agencies to increase the effective life of paved roads 31 ' under diverse climatic conditions, necessitating the development of improved asphalt products.

34

One object of the present invention is to provide improved asphalt-containing products having enhanced performance properties particularly at low polymer concentrations.

Another object of the present invention is to provide improved asphalt-containing products having enhanced performance properties which are substantially insensitive to the crude source of the asphalt.

Other objects will be readily apparent to those skilled in the art from a reading of this specification.

SUMMARY OF THE INVENTION

According to the present invention thermoplastic polyepoxy polymer-linked-asphalt compositions having unique and surprising properties are produced through the reaction of asphalt and epoxide-cσntaining polymers.

DETAILED DESCRIPTION OF THE INVENTION

^J t has been discovered that certain polymers may be reacted and linked with asphalt. The resulting reaction product is a novel polymer-linked-asphalt having unique and surprising properties. The term "polymer-linked-asphalt" as used herein refers to a polymer and asphalt composition in which the polymer is substantially covalently-bound to asphalt by ^{one or} more covalent bonds. The product polymer-linked- asphalt of the present invention provides a number of important performance characteristics, including:

improved resistance to permanent deformation (rutting);

improved resistance to flexural fatigue;

improved resistance to low temperature thermally-induced cracking; and

improved resistance to moisture damage (stripping).

The reactant asphalt and polymer, the reaction conditions, and the resulting polymer-linked-asphalt product are described below.

The Reactant Asphalt

All types of asphalts (bitumens) are useful in this invention whether they be natural or synthetic. Representative asphalts include: native rock, lake asphalts, petroleum asphalts, airblown asphalts, cracked or residual asphalts. Asphalts can be used containing a wide range of asphaltenes including asphalts containing more than 7 weight percent asphaltenes and typically more than 10 weight percent asphaltenes.

Preferred asphalts have a viscosity at 60°C of 100 to 20,000 poise, preferably 200 to 10,000, more preferably 300 to 4000 and still more preferably 400 to 1500 poise.

₀ 1 The Reactant Polymer Composition

02

₀₃ Reactant polymers useful in the present invention contain an

₀₄ epoxide moiety (oxirane) which reacts with the asphalt. The _nt - epoxide moiety may be represented by the following formula:

06

⁰⁷ 0

08 \ / \ /

0* 10

11

₁₂ Generally the reactant epoxide-containing polymers useful in

.- this invention will have a melt flow index in the range of

. . from 0.1 to 2000, preferably 0.5 to 500 and more preferably _ις 1 to 100. Generally, the reactant polymer will contain 0.01

_1fi or more weight percent epoxide moieties and preferably more

17 than 0.04 weight percent epoxide moieties based on the total _lβ weight of the reactant polymer. More preferably the reactant polymer will contain 0.05 to 10 weight percent

19 20 epoxide moieties and still more preferably 0.1 to 5 weight 21 percent epoxide moieties based on the total weight of the 22 reactant polymer. 23 24 Reactant polymers may be copolymers derived from two or more monomers (such as tetrapolymers) , preferably three monomers 25 (terpolymers) and most preferably two monomers. 26

27

Other reactant epoxy-containing polymers include: 28 epoxidized acrylate rubbers (for example, copolymers ethyl & butyl acrylate functionalized with glycidal methacrylate),

30 epoxidized neoprene, epoxidized polyisoprene, epoxidized 31 oils (for example, soya oil), epoxidized stryene-butadiene rubbers, epoxidized butadiene resins, epoxidized terpolymers

34

(e.g., EPDM), epoxidized polynorbornene, and epoxidized 1 butadiene-acrylonitrile rubbers. 2 3

Preferred Reactant Polymer Compositions 4 5

One preferred group of epoxide-containing reactant polymers 6 for use in the present invention are glycidyl-containing 7 polymers. Glycidyl-containing ethylene copolymers and 8 modified copolymers useful in the present invention are well 9 known in the polymer art and can readily be produced by 0 direct copoly erization in accordance with U.S. Patent No. 1 4,070,532, and PCT Application 85,223,367, the entire 2 disclosures of which are incorporated herein by reference. 3 Generally useful glycidyl-containing reactant polymers will 4 contain 0.02 or more weight percent glycidyl moieties and 5 more preferably 0.08 weight percent or more weight percent 6 glycidyl moieties based on the total weight of the reactant 7 polymer. The glycidyl moiety may be represented by the 8 following formula: 9 0

0 1 / \ 2 -0-CH ₂ -CH-CH ₂ 3 * More preferably the reactant polymer will contain 0.1 to 20 5 weight percent glycidyl moieties and still more preferably 6 0.2 to 10 weight percent glycidyl moieties based on the ⁷ total weight of the reactant polymer. 8 ⁹ Particularly preferred reactant copolymers useful in this 0 invention may be represented by the formula: E/X/Y/z, where 1 E is the copolymer unit -(CH ₂ CH ₂ )- derived from ethylene; 2 X is the copolymer unit -(CH _j CR.^)-, where ₁ is hydrogen, 3 methyl, or ethyl, and ₂ is carboalkoxy, acyloxy, or alkoxy * of 1-10 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 ₂ CR ₃ R ₄ )-, where R ₃ is hydrogen or methyl and ₄ is carboglycidoxy or glycidoxy (Y for example is derived from glycidyl acrylate, glycidyl methacrylate, or glycidyl vinyl ether). Additional comonomers, Z, include carbon monoxide, sulfur dioxide, acrylonitrile, or other monomers.

For this preferred embodiment of the invention, useful weight ratios of the E/X/Y/Z copolymer units are X is 0 to 50%, Y is 0.5 to 15%, Z is 0 to 15%, E being the remainder.

Still more preferred reactant copolymers are E/X/Y, where the weight percent of X varies from 0% to 40%; and the percent of Y varies from 1% to 10%; E being the remainder.

Especially preferred copolymers are E/Y, where the weight percent of Y varies from 1% to 10%, and E is the remainder.

It is also preferred that the epoxide-containing monomers, and more preferably the glycidyl-containing monomers, are incorporated into the reactant polymer by direct copolymerization and are not grafted onto the reactant polymer by graft polymerization.

The Reaction Conditions

The asphalt and reactant polymer are combined under conditions suitable to cause reaction and linking of the reactant polymer to the asphalt. Suitable conditions will vary greatly depending upon the particular asphalt and reactant polymer chosen and the desired properties of the product polymer-linked-asphalt. Conditions under which the

reaction occurs, i.e., time, temperature, type and quantity of each reactant can be determined empirically.

Surprisingly, it has been found that mixing of the reactant polymer and the asphalt alone does not produce sufficient reaction to dramatically improve the functional properties of the resultant asphalt mixture. An elevated temperature and sufficient time are required for the reaction of the reactant polymer and asphalt to occur. This is in contrast to many prior art polymer-modified asphalts wherein some polymer is blended with asphalt as an additive without the polymer ever substantially reacting with the asphalt. In the present invention the polymer-linked-asphalt product is formed by the covalent reaction of the reactant epoxide-containing polymer with asphalt.

Generally a reaction temperature of greater than 100 ^β C and preferably greater than 135°C is required along with a reaction time of greater than 1 hour and preferably greater than 5 hours. Typically the reaction temperature will be in the range 125 to 250 ^β C with a reaction time in the range 2 to 300 hours. Preferably the reaction temperature will be in the range 150 to 230 ^β C with a reaction time in the range 3 to 48 hours. Still more preferably the reaction temperature will be in the range 180 to 220 ^β C with a reaction time in the range 4 to 24 hours.

Generally the reaction will take place at atmospheric pressure. Higher or lower pressures can of course be used but are generally less economical. Also the reactants will generally be continuously mixed during the reaction.

The reactant polymer and the asphalt reactant are combined such that the reactant polymer comprises 0.5 to 20 weight

percent of the reaction mixture. Preferably the reactant polymer comprises 1 to 10 weight percent, more preferably 1 to 5 weight percent and most preferably 1 to 3 weight percent of the reaction mixture.

It has surprisingly been found that both the quantity of reactant polymer and the epoxide content of the reactant polymer, within the limits described above, are critical to achieve desirable polymer-linked-asphalt rheology and to avoid gelation of the polymer-linked-asphalt. It has been found that it is preferable to select the reactants and reaction conditions so that substantially all of the epoxide moieties are reacted within the polymer-linked-asphalt product.

Another surprising feature of the present invention is that the reaction of the epoxide-containing polymer and the asphalt can occur within an oil-in-water emulsion. In other words, the desired polymer-linked-asphalt product can develop as the reaction goes to completion within the emulsified particles. Generally, a reaction accelerating catalyst will be utilized to accelerate the reaction at normal emulsion storage temperatures in the range of 20°C to 100 ^β C.

One advantage of emulsifying an epoxide-containing polymer/asphalt blend is that emulsification is more readily accomplished in the unreacted state. It is easier to emulsify the lower viscosity unreacted epoxide-containing polymer/asphalt blend than it is to emulsify the higher-viscosity reacted polymer-linked-asphalt. A second advantage is that by permitting the polymer/asphalt reaction to occur within the emulsified asphalt particle, it is possible to use higher levels of epoxy-containing polymer

01 than is practical in normal paving asphalts. This is 02 because the viscosity of oil-in-water emulsions is not dependent on the oil-phase (e.g., polymer-linked-asphalt 03 04 phase) viscosity.

05

Asphalt emulsions are well known in the paving art. 06 07 Emulsions of this embodiment of the current invention 08 comprise water, asphalt, epoxide-containing polymer, and surfactants. Generally, the asphalt and epoxide-containing 09 polymer will be blended just prior to their emulsification 10 lϊ and before any significant reaction has occurred. The reaction of the epoxide-containing polymer and asphalt will 12 occur within the oil phase of the emulsion. 13 14

A typical emulsion will comprise: 15 16

(a) 35 to 80 wt. % asphalt (preferably 60 to 75 wt. %); 17 18

(b) 0.05 to 20 wt. % epoxide-containing polymer 19 (preferably 0.5 to 5 wt. %); 20 21

(c) 0.05 to 5.0 wt. % surfactant (preferably 0.5 to 22 2.0 wt. %) ; and 23 24

(d) water to make 100%. 25 26

The surfactant can be any of the well-known ionic and 27 non-ionic emulsifying agents used in the paving art. See, 28 for example, U.S. Patent 4,822,427, the entire disclosure of 29 which is incorporated herein by reference. Salts of fatty 30 acids or quarternary amines are well-known ionic 31 emulsifiers. Preferably catalysts will be included in the 32 emulsion formulation to accelerate the polymer-linked 33 asphalt reaction at normal emulsion storage temperatures. 34

The Polyaer-Linked-Asphalt Reaction Product

The product of the reaction of the present invention is a novel thermoplastic polyepoxy polymer-linked-asphalt. The term "polyepoxy polymer-linked-asphalt" refers to a polymer and asphalt composition in which the polymer is substantially covalently-bound to asphalt by one or more covalent bonds formed by reaction of asphalt with one or more epoxide moieties in the reactant polymer. By the term "thermoplastic" it is meant that the polymer-linked-asphalt product softens when exposed to heat and returns to substantially its original condition when cooled.

The exact mechanism of the linking of the reactant polymer and asphalt in effecting the improved polymer-linked-asphalt product is unknown, but it is not necessary to know the mechanism in order to understand the present invention.

However, without being bound by the theory, it is believed that the epoxide moiety reacts with nucleophilic sites in the asphalt (e.g., carboxylic acid, pyrollic or phenolic functional groups) to covalently bond (link) the polymer and the asphalt. hereas simple mixing of polymers into asphalt can introduce an elastic structure through the molecular entanglement of the polymer molecules within the asphalt, reacting the polymer onto the existing molecules in the asphalt, as taught in this invention, results in a more effective use of the polymer and a substantial improvement in the asphalt's viscoelastic properties.

The formation of the product polyepoxy polymer-linked- asphalt of the present invention can be measured by an increase in reactant asphalt viscosity, but more preferably dynamic mechanical analysis (DMA) is used to measure the product properties.

01 The viscous and elastic properties of an asphalt are 02 important performance indicators. Dynamic mechanical 03 analysis properties are determined using a dynamic 04 mechanical analyzer (DMA), for example, Rheometrics 05 RDA-600. This instrument resolves the viscous and elastic 06 nature of asphalt samples tested at various temperatures and 07 shear rates. 08 09 Using the DMA, sinusoidal strains are imposed as an 10 oscillatory shear to samples in a parallel-plate viscometer configuration. The amplitude of the stress is measured by 11 determining the torque transmitted through the sample in 12 ₁₃ response to the imposed strain. The strain amplitude and ₁ . frequency are input variables, set by the operator.

15

₁₆ Depending on the relative viscous and elastic nature of the

₁₇ sample at the particular test conditions, the sinusoidal .. stress response to the imposed sinusoidal shear strain may be out of phase. If the asphalt behaves as a purely viscous

19 liquid (no elasticity) the peak stress response will lag 90° 20 behind the imposed sinusoidal shear strain. With increasing 21 elastic response, resulting for instance from the polymer 22 linking to the asphalt, the peak stress response becomes 23 increasing in-phase with the shear strain. 24 25

The DMA determines the peak stress and peak strain. The 26 ratio of the peak stress to the peak strain is the absolute 27 value of the modulus, or the complex shear modulus, |G*|. 28 29

|G*| - peak stress/peak strain Eq. 1 30 31 32 33 34

The in-phase component of |G*|, the dynamic shear storage modulus, or G', equals the stress in phase with the shear strain divided by the strain, or:

G'-JG*I cos (Δ) Eq. 2

Δ is the phase shift angle between the applied maximum shear strain and the maximum shear stress.

The out-of-phase component of |G*|, the dynamic shear loss modulus, or G", equals the stress 90" out of phase with the shear strain divided by the strain, or

G"-|G*| sin (Δ) Eq. 3

Typical units for |G*|, G' and G" are Pascals (SI) or dynes/cm ² (cgs).

An important performance-related property of an asphalt is the ratio of G" to G' . This is called the loss tangent.

Loss Tangent - tan (Δ) - G"/G' Eq. 4

A detailed discussion of DMA is published in "Asphalt and Polymer Modified Asphalt Properties Related to the Performance of Asphalt Concrete Mixes," Proc. of the Association of Asphalt Paving Technologists, Vol. 58, (1988) by J. L. Goodrich.

The increase in the elastic nature of an asphalt due to effective polymer-linking is indicated by sustained desirable rheology (low loss tangents) at temperatures up through 80 ^β C using DMA.

01 A second indicator of an effective polymer-linked-asphalt 02 product of the present invention is a substantially storage 03 stable viscosity. By "storage stable viscosity" it is meant 04 that after completion of the reaction time there is no 05 evidence of gelation and the viscosity of the product does 06 not increase by a factor of 4 or more during storage at 07 163°C for 10 days. Preferably the viscosity does not 08 increase by a factor of 2 or more during storage at 163°C 09 for 10 days. More preferably the viscosity increases less 10 than 25% during 10 days of storage at 163*C.

11

₁₂ A substantial increase in viscosity while the asphalt is

₁₃ stored is not desirable due to the resulting difficulties in

₁₄ handling the product and meeting and maintaining product

₁₅ specifications at the time of sale and use.

16

₁₇ A third indicator of an effective polymer-linked-asphalt

₁₈ product of the present invention, in addition to a low loss _ιg tangent and storage stable viscosity, is homogeneity.

20 Homogeneity of the polymer-linked-asphalt product is

₂₁ evidenced by there being no observation of phase separation

__ or the formation of a surface "skin" in samples stored at

_ ₃ 177 ^β C (350°F) for typically 72-96 hours after completion of

.4. the reaction time.

25 _ The product polymer-linked-asphalt of the present invention

. will typically exhibit the following loss tangent, storage stability and homogeneity properties: 28

29

30

31

32

33

34

TABLE I

Polymer Content (wt.% in Polymer-

Loss Tangent Linked- Storage Stabili @60 ^β C @80 ^β Asphalt) Homogeneity

Broadly <50 <100 0.5 -20 Smooth, no separation, not gelled.

Preferred 0.01 - 20 0.01 - 50 1 - 10 Smooth, no separation, not gelled.

More Preferred 0.01 - 10 0.01 - 20 1 - 5 Smooth, no separation, not gelled.

Most

Preferred 0.01 - 5 0.01 - 10 1 - 3 Smooth, no separation, not gelled.

Uses of the Polymer-Linked-Asphalt Reaction Product

The thermoplastic polymer-linked-asphalt reaction product of the present invention (polyepoxy polymer-linked-asphalt) are useful in various types of asphalt applications including paving, industrial and roofing applications. The reaction product may be used neat or in emulsified form. Asphalt emulsions are well known in the paving art and comprise water, asphalt (including the polymer-linked-asphalt of the present invention) and surfactants.

An especially preferred use is in road paving in which hot polymer-linked-asphalt is mixed with hot mineral aggregate to make asphalt concrete mixes. The polymer-linked-asphalts of the present invention are particularly effective in hot mix paving compositions at low levels of reactant polymer

generally in the range of 1 to 10 weight percent, preferably in the range 1 to 5 weight percent and more preferably in the range 1 to 3 weight percent of the reaction mixture.

Other Additives and Modifications

Reaction controlling agents, such as catalysts and quenching agents, can be used to accelerate, decelerate or terminate the reaction of the epoxide moiety in the reaction mixture.

Many catalysts can be used for accelerating the epoxide-containing polymer/asphalt reaction rate. Representative catalysts are disclosed in: "Handbook of Epoxy Resins", H. Lee and K. Neville, McGraw-Hill Book Company, Inc., New York 1967 and "Epoxy Resins", H. Lee and K. Neville, McGraw-Hill Book Company, Inc., New York 1957, the disclosures of which are incorporated herein by reference.

Suitable catalysts for accelerating the reaction of the epoxide-containing reactant polymer with asphalt, particularly in promoting the reaction at low temperatures (for example, in the range of 20 to 100°C) include organometallic compounds and tertiary amine compounds. Examples of organometallic catalysts include: lead octanoate, lead naphthenate, tetra-sec-butyl titanate, hydrocarbon mono-, or di-, or polycarboxylic acid metallic salts which provide a source of catalytic cations (e.g., Al ⁺⁺⁺ , Cd ⁺⁺ , Ca ⁺⁺ , Cu ⁺⁺ , Fe ⁺⁺ , ln ⁺⁺⁺ , Mn ⁺⁺ , Sb ⁺⁺⁺ , Sn ⁺⁺ , and Zn ⁺⁺ ), e.g.: stannous octoate, zinc stearate, dibutyltindilaurate. Examples of tertiary amine compounds include: α-methylbenzyl dimethylamine, trimethylamine, triethylamine, benzyldimethylamine, dimethylaminomethyl phenol (DMP-10), triethanolamine,

_nl tri(hydroxymethyl)aminomethane, m-diethylaminophenol, benzyldimethylamine (BDMA), tris(dimethylaminomethyl)phenol

02

₀₃ (DMP-30), poly(ethylene/dimethylamino ethylmethacrylate) ,

04 s-triazine, triallylcyanurate, benzyltrimethylammonium 05 hydroxide, tri-2-ethylhexoate salt of _n£ tris(dimethylaminomethyl)phenol. UO

07

08 Other accelerators include: triphenyl phosphite, ethylene 09 sulfite, and organophosphines (e.g.,

₁₀ tricyclohexylphosphine).

11

₂ Polymers not containing an epoxide functionality may be

13 added to the asphalt in addition to the epoxide-containing 14 reactant polymer used in this invention. These added ... polymers may include, but are not limited to, polymers _lg having the composition E/X/Z, where E is derived from ₁₇ ethylene, X is derived from alkyl acrylates, alkyl _1fi methacrylates, vinyl esters, or alkyl vinyl ethers.

Optionally, Z may be part of the copolymer, wherein z is

19

20 derived from carbon monoxide, sulfur dioxide, or

₁ acrylonitrile. These copolymers, which do not have asphalt reactive functionality, may have weight ratios of the E/X/Z

22 23 components in the range X is 5% to 50%, Z is 0 to 15%, E 24 being the remainder. Preferred ratios are X is 15% to 40%, Z is 0 to 10%, and E being the remainder. These non- 25 reactive diluent polymers can be combined into the asphalt, 26 with the epoxide-containing copolymers reactant of this 27 invention, so they comprise 0% to 18% of the final

28

_Q polymer-linked-asphalt composition, preferably 0 to 15%, more preferably 0 to 10%.

31

The preferred E/X/Y/Z reactant copolymer used in the present invention can be used either as the principal reactant with an asphalt, or with an additional co-reactant polymer. In

01 this case the preferred reactant copolymer is used to link 02 another copolymer indirectly to asphalt. For example, 03 E/X/Y/Z can be allowed to react with an asphalt for one 04 hour, followed by the addition of a coreactant polymer 05 E/X/N/Z. In another example, useful products can be 06 manufactured in which an epoxy-containing polymer and a 07 coreactant polymers react with each other after a minor 08 amount of epoxide-containing polymer/asphalt reaction has 09 occurred. Such products may be particularly useful in 10 roofing compositions. These coreactant polymers preferably .. have nucleophilic functionality that can react with the

₁₂ epoxy or glycidyl moiety of E/X/Y/Z. Such nucleophilic

₁₃ functional groups include acids, alcohols, amines and

₁₄ thiols. A preferred coreactant polymer, E/X/N/Z, includes

₁₅ compositions where N is derived from an alkylacrylic acid,

₁₆ acrylic acid, alkyl anhydride, or mono-alkyl maleate. The

₁₇ use of the E/X/N/Z as a coreactant can improve the _lfl effectiveness of the E/X/Y/Z asphalt blend.

19

20 Preferred weight ratios of the E/X/N/Z copolymer useful as a

₂₁ coreactant with E/X/Y/Z copolymers are X is 0 to 50%, N is

₂₂ 0.5 to 25%, Z is 0 to 15%, E being the remainder.

23

_ . The advantages of the present invention will be readily

.- apparent from consideration of the following examples. It

_ _fi is understood that these examples are provided for the sake

₂₇ of illustration and comparison only and not as a limitation

_2a on the scope of the invention.

29 30 EXAMPLES 31

_. Data from the samples and tests described below appear in

33 Tables II-VI. 34

Preparation of Samples

To 400 grams of asphalt heated to 204 ^β C (400°F) was added various polymers. The mixture was blended under nitrogen using a propeller-type stirrer for two hours while maintaining the temperature at 204°C. The blended mixture was stored in a 204 ^β C oven for two additional hours and then transferred to a 163-177 ^β C (325-350 ^β F) oven for storage for up to 4 days.

Measurement of the Dynamic Viscoelastic Properties

The dynamic viscoelastic properties of asphalts, polymer asphalt blends and polyme -linked-asphalts were measured using DMA on aged residues from Rolling Thin Film Oven (RTFO), ASTM D 2872.

Parallel plates of different diameters were used to obtain the data at different temperatures:

Sample Type Plate Diameter Test Temperature

RTFO residue 8 mm -30°C to +10 ^β C RTFO residue 25 mm -10 ^β C to +50 ^β C RTFO residue 40 mm +50°C to +100 ^β C

Sample specimen thickness between the parallel plates was 1 to 2.5 mm.

Strains were kept small (<0.5%) at low temperatures and increased at higher temperatures, but were kept within the linear viscoelastic region as indicated by strain sweeps. Frequencies from 0.1 radians/sec (0.0159 Hz) to 10 radians/- sec (1.59 Hz) were swept for each test temperature in five equal steps per frequency decade.

The loss tangent (G"/G') values at 20°C, 40 ^β C, 60 ^β C, and 80 ^β C for a variety of samples are shown in Tables II-VI.

Resistance of Asphalt Concrete to Permanent Deformation at 40 ^β C

Creep studies were conducted at 40°C using 10.2 cm by 20.3 cm (4 in. by 8 in.) cylindrical specimens of asphalt concrete (95% Mineral Aggregate, 5% Binder). Axial loading of the samples, 172 KPa (25 psi), was done in a triaxial cell. The asphalt concrete samples were tested with no con- fining pressure. The creep deformation was measured axially in the middle 10.2 cm (4 in.) portion of the test cylinder. The deformation was recorded during the 60-minute loading period and during a 30-minute recovery period.

The deformation over tine is expressed as the slope of the creep modulus versus time in Table IV. The more deformation (an undesirable condition), the more negative the slope. The loss tangent (G"/G'), at 20 ^β C, 40 ^β C, 60 ^β C, and 80°C, for each asphalt, polymer-modified asphalt and polymer-linked asphalt used in the creep studies is also shown in Table IV.

The data in Table IV demonstrates that the polymer-linked- asphalts of the present invention, Run Nos. 303 and 304, provide excellent resistance to creep deformation in asphalt concrete mixes. Asphalt "A" in Run No. 300 is an asphalt which is prone to deformation or rutting at high temperatures. Asphalt "B" in Run No. 301 is an example of one of the more rutting resistant conventional asphalts. The polymer-linked-asphalts (using an asphalt similar to Asphalt "A") in Run Nos. 303 and 304 have far superior resistance to deformation than either of the "conventional" asphalts or blended polymer-modified asphalt (Run No. 302) as measured by the slope of the creep modulus versus time.

1 Beam Fatigue Life of Asphalt Concrete at 25 ^e C 2

Beam fatigue equipment was used to measure flexural fatigue 3 4 life was operated in a controlled stress mode and employed a 5 four-point loading design as described in "Asphalt and 6 Polymer Modified Asphalt Properties Related to the 7 Performance of Asphalt Concrete Mixes, "Proc. of the 8 Association of Asphalt Paving Technologists, Vol. 58, (1988) 9 by J. L. Goodrich; Santucci, L.E. and Schmidt, R.J., "The 0 Effect of Asphalt Properties on the Fatigue Resistance of . . Asphalt Paving Mixtures," Proc. of the Association of ₁₂ Asphalt Paving Technologists, Vol. 38, pp. 65-97 (1969); and

_ Yao, Z. and Monismith, CL. "Behavior of Asphalt Mixtures ,4. with Carbon Black Reinforcement," Proc. of the Association _ις of Asphalt Paving Technologists, Vol. 55, pp. 564-585 ₁₆ (1986).

17 _ιa The loading cycle consisted of 0.05 second pulse load _ιq followed by a 0.55-second rest period (100 cycles 2 _Q per minute) .

21

The bending load was adjusted to yield prescribed initial

__ strains. The strains reported are those set after a pre- ₂₄ conditioning period of 200 load applications. The fatigue „ life data are shown in Table V. The loss tangent (G"/G'), _g at 20 ^β C, 40 ^β C, 60 ^β C, and 80°C, for each asphalt, polymer- ₂ modified asphalt, and polymer-linked-asphalt used in the

28 flexural fatigue life experiments is also shown in Table V. 29

The data in Table V demonstrates that asphalt concrete made 30 31 using the polymer-linked-asphalt of the present invention, Run Nos. 403 and 404, have superior resistance to fatigue

33 cracking at low initial strains compared to Run Nos. 400, 34 401, and 402 as measured by cycles-to-fail at 25 ^β C. This is

-23-

particularly surprising, considering the low polymer level of the mixes in Run Nos. 403 and 404.

Good resistance to fatigue cracking is shown by the data in Table V to be correlated to binders which have low loss tangents at the test temperature. The magnitude of the separate dynamic binder moduli G' (the elastic component) and G" (the viscous component) are not as important to fatigue life as is the G"/G' ratio. The loss tangent ( G ⁿ /G ^f ) is also more correlated to the fatigue life than is the magnitude of the complex viscosity.

Asphalt-Aggregate Adhesion in Wet and Dry Conditions

The durability of the asphalt-aggregate bond under moist conditions was measured using the "split tensile strength" method, ASTM D-4867. In this method, cylindrical asphalt concrete specimens, produced by using asphalt, polymer- modified, or polymer-linked-asphalt and a dense-graded mineral aggregate, were loaded diametrically until the specimen split apart. The peak load applied to the specimen was recorded as a measure of the mix strength. The strength of the asphalt concrete cylinders was measured both as dry specimens and after vacuum saturating the specimens in water at 60°C. The data for asphalt concrete specimens produced from asphalts, polymer-modified asphalt or polymer-linked- asphalt are shown in Table VI along with the percent of split tensile strength retained after the moisture treatment for each specimen.

The data demonstrates that the mixes in Run Nos. 505, 506 and 507 which used the polymer-linked-asphalts of the present invention retained their dry strength better after water soaking than did the control asphalts of Run Nos. 500

and 501. This may indicate that the resistance of the modified asphalt's cohesive strength to water is improved, or it may also indicate that the additional chemical functionality/polarity provided by the polyepoxy polymer- linked-asphalt improves that wet strength of the asphalt- aggregate bond. In either case, the data demonstrates that the mix benefits from the polymer-linked-asphalt of the present invention.

01

02 TABU: II

03 EFFEO OF EPOXIDE REAαANTS ON POLYMER-UNKED-ASPHALTS

04

05

06

07

08

09

10

11

12

13

14

15

16

17

18

19

20 I t

21 uι

I

22

23

24

25

26

27

28

29. • Asphalt = 1500 Poise al 60C

30 Note 1. These polymers were produced according to UK Patent No. 2022597; that is, by attempting lo gran the GMA monomer onto an E/VA copolymer.

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s;?? ???? τ τ ttn

01

02

03

04

05

06

07 TABLE IV

08 RESISTANCE OF ASPHALT CONCRETE TO PERMANENT DEFORMATION at 40C

09

10

11

12

13

14

15

16

17

18

19

20 t

21 I

22

23 VA « vinyl acetate Asphalt A < 2180 Poise al όOC

24 nBA -» normal butyl acrylate Asphalt B ■ 1425 Poise at 60C GMA «■ glycidyl me hacrylale Asphalt C i i 1500 Poise at 60C

25

26

27

28

29

30

31

32

33

34

35

36

01 02 03 04 05 06 TABLE V 07 08 BEAM FATIGUE UFE OF ASPHALT CONCRETE at 25C 09 10 11 12 POLYMER DESCRIPTION POLYMER-ASPHALT ASPHALT CONCRETE DYNAMIC RHEOIOGICAL 13 BLEND FORMULA BEAM FATIGUE UFE ANALYSIS 14 Cycjes-to-Fail ot 25C

Run Ethylene, Co- GMA, Meh Polymer Asphalt GMA % Initial Beam Microstrain Loss Tangent (Tan Delia) 15 No. Wt. % Monomer Wt. %1 Wt. % Index Wt. % Wt. % In blend 1000 700 400 200 25C I 40C I 60C I 80C 16 17 400 0 100 (A) 0 NA 1000 20000 100000 7.7 32.7 187 1400 20000 50000 200000 2000000 2.5 4 18 401 0 100 (B) 0 23 130 19 402 60.0 VA 40.0 0.0 48-66 5 95 (0 0 NA 1000 20000 100000 3.3 7.1 38 220 I 20 403 64.0 nBA 27.6 8.4 10.6 2 98 (0 0.17 3000 30000 1000000 >10000000' 3.5 3.5 4.6 11.7 to 21 404 61.0 nBA 34.0 5.0 -10 3 97 (0 0.15 10000 60000 1000000 >10000000' 3.5 3.3 5.8 18.5 00

I 22 estimate 23 ,VA » vinyl acetate Asphalt A- 2180 Poke al 60C 24 nBA « normal butyl acrylale As halt B - 1425 Poise at 60C GMA » glycidyl melhacrylate Asphalt C - 1500 Poise al 60C 25 26 27 28 29 30 31

35 36

01

02

06 TABLE VI

07

08 ASPHALT-AGGREGATE ADHESION in WET and DRY CONDITIONS

09

10

11

12

13

14

15

16

17

18

19

20

21

22

23 nBA s normal butyl acrylate Asphalt « 1500 Poise at 60C

24 GMA « glycidyl methacrylate ASTM D-4867 (Effect of Moisture on Asphalt-Concrete Paving Mixtures)

25

26

27

28

29

30

31

32

33

34

35

36