Block copolymers and polymer-modified bitumen derived therefrom

Abstract

To provide enhanced binder formulations to further improve properties of asphalt mixes, such as improved elastic responses, decreased fatigue cracking, reduced low temperature cracking, and reduced rutting, caused by load factors, weather conditions, etc. so as to improve the performance of the resulting roads.SOLUTION: Disclosed herein are linear block copolymers of formula A-B-A' or A-B*B-A', where blocks A and A' are polystyrene blocks, block B is a poly(conjugated diene) block and the symbol * is a coupling agent having a vinyl content of 10-60 mol%. The block copolymers have a polystyrene content of 20-35 wt.%, relative to the total weight of the block copolymer, and a molecular weight of 200,000-300,000 g / mol. The block copolymers can be used with a wide variety of asphalt grades, and are valuable for producing homogeneous polymer modified asphalt compositions having an effective combination of performance properties, such as acceptable viscosity, good elastic response to an applied stress, and a low non-recoverable creep compliance. The combination of vinyl content and polymerization technology allows a high solution concentration during polymerization without excessive processing viscosity.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present disclosure relates to block copolymers and their use to produce polymer-modified bitumen and asphalt compositions derived therefrom. [Background technology]

[0002] The use of bitumen in the production of materials for highway and industrial applications, such as asphalt, is known. Bitumen is the primary hydrocarbon binder used in the fields of road construction and civil engineering. To be used as a binder in these various applications, it is desirable for bitumen to have certain mechanical properties, such as viscoelastic, adhesive, and / or cohesive properties. The mechanical properties of bitumen and binder compositions containing bitumen are determined by the softening point T sp The viscosity is measured by standardized tests such as determination of penetrability and other rheological characteristics. Summary of the Invention [Problem to be solved by the invention]

[0003] Polymer modifications of bitumen have been used to improve properties, however, there continues to be a need for enhanced binder formulations to further improve the properties of asphalt mixes and improve the performance of the resulting roads, such as improved elastic response, reduced fatigue cracking, reduced low-temperature cracking, and reduced rutting caused by loading factors, weathering conditions, etc. [Means for solving the problem]

[0004] (Summary of the Invention) In one embodiment, a linear sequential block copolymer is disclosed. The block copolymer has the formula AB-A' or (AB) n -X-(B-A') mwhere A and A' are polystyrene blocks and B is a poly(conjugated diene) block. n and m are 1 or greater, and X is a coupling agent. Block B has an average vinyl content of 10-60 mol %. The polystyrene content of the entire polymer is in the range of 20-35 wt %. The copolymer has a molecular weight in the range of 200,000-300,000 g / mol.

[0005] In embodiments, the block copolymer has the formula (AB): n -X-(B-A') m wherein n and m have a value of 1, and up to 25 wt. %, based on the total weight of the block copolymer, of the structure (AB): n -X-(B-A') m wherein n and m have values ​​greater than 1 and less than or equal to 5.

[0006] In another embodiment, a polymer modified bitumen is disclosed. The polymer modified asphalt has the formula (i) AB-A' or (AB) as set forth above. n -X-(B-A') m (ii) at least one base bitumen; and (iii) optionally, at least one crosslinker.

[0007] In another embodiment, a method for preparing a polymer-modified bitumen composition is described. The method comprises, consists essentially of, or consists of forming a mixture of a block copolymer and bitumen, optionally adding a crosslinking agent, and blending at 140-220° C. to form the polymer-modified bitumen composition. The crosslinking agent can be based on a sulfur donor, peroxide, or any other chemical commonly used in industry to crosslink styrenic block copolymers in bitumen. DETAILED DESCRIPTION OF THE INVENTION

[0008] As used herein, the following terms have the following meanings:

[0009] "Molecular weight" refers to the styrene equivalent molecular weight of a polymer block or block copolymer in g / mol. Molecular weight can be measured by gel permeation chromatography (GPC) using polystyrene calibration standards, as performed in accordance with ASTM 5296-19. The chromatograph is calibrated using commercially available polystyrene molecular weight standards. The molecular weight of a polymer measured using a GPC so calibrated is the styrene equivalent molecular weight. The styrene equivalent molecular weight can be converted to true molecular weight if the styrene content of the polymer and the vinyl content of the diene segments are known. The detector can be a combination of ultraviolet and refractive index detectors. Molecular weights expressed herein are measured at the peak of the GPC trace, and the measurements can be converted to true molecular weight, generally referred to as the "peak molecular weight" (M p When not converted to true molecular weight as above, the molecular weight quoted refers to the "styrene equivalent peak molecular weight."

[0010] The "vinyl content" of a polymer or block copolymer refers to the amount of vinyl groups generated upon addition of a conjugated diene via a 1,2-mechanism, resulting in adjacent olefinic or vinyl groups on the polymer backbone. Vinyl content can be measured by nuclear magnetic resonance spectroscopy (NMR) and is generally expressed as the mol% of conjugated diene moieties. In embodiments, the vinyl content can be tapered, present in blocks, or uniformly distributed. At a constant temperature, the vinyl content of a polymer can be controlled by the concentration of the microstructure control agent during polymerization. If the dosage is constant, the vinyl distribution is approximately uniform. If the dosage is gradually increased during polymerization, the distribution will be tapered. If the dosage is increased suddenly, typically from zero to a large amount, the vinyl will be distributed in blocks, initially low in vinyl and eventually high in vinyl.

[0011] "Coupling efficiency" (CE), expressed as % CE, is calculated from the GPC trace using the weight percent values ​​of the coupled polymer and the weight percent values ​​of the uncoupled polymer. The weight percent of the coupled and uncoupled polymers is determined using the output of a differential refractive index detector. The intensity of the signal at a particular elution volume is proportional to the amount of material whose molecular weight corresponds to the polystyrene standard detected in that elution volume. Therefore, the area under the curve for the MW range corresponding to the coupled polymer is representative of the weight percent of the coupled polymer, and similarly for the uncoupled polymer. % CE is given by 100 × (weight percent of coupled polymer) / (weight percent of coupled polymer + weight percent of uncoupled polymer). For example, if the coupling efficiency is 80%, the polymer contains 20% diblock and 80% triblock and multiarm blocks.

[0012] "Polystyrene content" or PSC refers to the percent weight of polymerized styrene in a block copolymer, calculated by dividing the sum of the molecular weights of all polystyrene blocks by the total molecular weight of the block copolymer. PSC can be determined using proton-NMR.

[0013] "Liquid asphalt" and "bitumen" are used interchangeably and refer to the substance in both natural and manufactured forms.

[0014] Asphalt (Europe) or "asphalt mix" (USA) refers to a mixture of aggregate fractions and bituminous binders, which is the base material for the binding layer of road construction.

[0015] "Polymer modified asphalt" or PMA is typically used in the United States, while "polymer modified bitumen" or PMB is typically used in Europe, and these refer to bitumen binders such as "polymer modified bitumen" binders or "polymer modified asphalt" binders.

[0016] The MSCR or "Multiple Stress Creep Recovery" test, also listed in AASHTO TP70 and AASHTO MP19, refers to a creep and recovery test to evaluate the potential of a binder to undergo permanent deformation, eliminating the need for separate tests such as elastic recovery, toughness and tenacity, and load-measured elongation to demonstrate that an asphalt binder is sufficiently polymer-modified. In the MSCR test with a dynamic shear rheometer (DSR), an asphalt binder sample is subjected to a 1-second creep load followed by a 9-second recovery, spanning multiple stress levels of 0.1 kPa and 3.2 kPa, with 10 cycles per stress level.

[0017] The present disclosure relates to linear sequential styrenic block copolymer (SBC) compositions optimized for performance-grade paving applications, particularly by the Multiple Stress Creep Recovery (MSCR) test. The SBCs, in some embodiments, may be referred to herein as "linear sequential block copolymers" because they are sequential in structure, even though the production process involves coupling through the use of coupling agents, and the SBC compositions may contain some multi-arm species.

[0018] Linear Sequential Styrenic Block Copolymer (SBC) SBC is AB-A' or (AB) n -X-(B-A') m wherein X is a coupling agent, and n and m are 1 or greater.

[0019] The blocks A and A' are vinyl aromatic blocks having different molecular weights and comprising styrene as the major component and structurally related vinyl aromatic monomers as minor components in a mixture selected from the group consisting of o-methylstyrene, p-methylstyrene, p-tert-butylstyrene, 2,4-dimethylstyrene, α-methylstyrene, vinylnaphthalene, vinyltoluene, vinylxylene, 1,1-diphenylethylene, or combinations thereof. In certain embodiments, the A and A' blocks have different molecular weights, i.e., a small block and a large block, and the difference in MW between the small block and the large block is in the range of 3,000 to 8,000, preferably in the range of 3,500 to 7,000.

[0020] In an embodiment, the SBC has 20-35 wt %, or 23-33 wt %, or 27-33 wt %, or 29-33 wt % of the PSC, based on the total weight of the SBC.

[0021] Block B is a conjugated diene block, and the diene can be any conjugated diene. Alternatively, the conjugated diene has 4 to 8 carbon atoms. In embodiments, the conjugated diene is butadiene or isoprene monomer, and contains or contains substantially minor proportions, e.g., up to 10% by weight, of structurally related conjugated dienes, such as 2,3-dimethyl-1,3-butadiene, isoprene, 1,3-pentadiene, farnesene, myrcene, and 1,3-hexadiene. Alternatively, substantially pure butadiene or substantially pure isoprene can be used to prepare the conjugated diene block. In embodiments, the conjugated diene block comprises a mixture of butadiene and isoprene monomers. In embodiments, the conjugated diene block contains residual coupling agent.

[0022] In embodiments, block B has a vinyl content of 20-60 mol%, or 25-55 mol%, or 35-45 mol%, or greater than 30 mol%, or less than 50 mol%. It is recognized that the vinyl content is averaged, and varying the addition of microstructure control agent can produce a non-uniform product with tapered or blocky vinyl content. In embodiments, the vinyl content is distributed evenly throughout the conjugated diene block, or distributed as a gradient in the conjugated diene block, or present in separate blocks of standard vinyl content and high vinyl content, where standard refers to levels typically obtained when polymerized without a microstructure modifier, and thus less than 20%, or typically in the range of 7-15%, while high vinyl content refers to levels greater than 20%, e.g., in the range of 22-50%, or 25-40%, or even 75%, obtained with a microstructure modifier. In embodiments, the vinyl content of block B is controlled by the addition of a microstructure modifier and / or by controlling the temperature of the addition and reaction in turn.

[0023] In embodiments, the SBC is AB-A' or (AB) n -X-(B-A') m where A and A' together form the polystyrene portion of the block copolymer molecule, and n and m have a value of 1. In embodiments, the SBC has a formula of up to 20% by weight, or less than 25% by weight, or 3-15% by weight of the structure (AB) n -X-(B-A') m wherein n and / or m are greater than 1, or have a value up to 5, or range from 2 to 4.

[0024] In embodiments, the SBC has a molecular weight of 200,000 to 300,000 g / mol, or greater than 210,000 g / mol or less than 290,000 g / mol, or a molecular weight of 220,000 to 270,000 g / mol. Preparation of linear sequential SBCs SBCs can be produced via step-growth polymerization or through polymerization and coupling. Polymerization can be accomplished by contacting the appropriate monomers with an organoalkali metal compound in a suitable solvent at temperatures ranging from -150°C to 200°C, or above -100°C, or from 0°C to 110°C, or below 150°C, or at ambient temperature.

[0025] In embodiments, block copolymers are prepared by anionic polymerization techniques, sequentially polymerizing styrene to form a polystyrene block, then continuing the polymerization by adding butadiene to form a butadiene block, and polymerizing styrene to form a third block. The sequential polymerization ensures that each polymer molecule contains a small styrene block and a large styrene block, if desired, and the coupling of AB and A'-B diblocks, which are polystyrene-polybutadiene with small and large styrene blocks, results in a statistical distribution of styrene blocks of different sizes throughout the molecule. In addition, the sequential polymerization minimizes the presence of residual diblock material.

[0026] In embodiments, block copolymers are prepared through polymerization and coupling. The coupling technique provides better control over the size of the styrene block and reduces the viscosity of the polymer solution during the polymerization process, since the viscosity of the living polymer depends on the length of the two diblock living polymers due to the association of the living polymers. Lower viscosity allows for higher polymer concentrations per batch, thereby increasing run rates and reducing the energy costs associated with solvent removal.

[0027] In an embodiment for preparing an SBC with different vinyl aromatic blocks, the process begins by sequentially polymerizing styrene anionically using an organic alkali metal compound to form a single molecular weight polystyrene block, or by adding additional organic alkali metal compounds during the polymerization of styrene to form a mixture of styrene blocks of different molecular weights. Polymerization continues with the addition of butadiene to form a portion of the desired butadiene block, followed by the addition of a microstructure modifier and the remaining butadiene to form a diblock for coupling, or a sequential polymer before the addition of styrene. The butadiene polymerized before the addition of the microstructure modifier has a low vinyl content, while the butadiene polymerized after the addition of the microstructure modifier forms a separate high-vinyl section in the polybutadiene block. The diblocks can be coupled to complete a linear block copolymer with separate high-vinyl and low-vinyl polybutadiene blocks.

[0028] In embodiments, the coupling agent is selected from di- and multi-functional molecules capable of coupling living anionic polymers, such as methoxy or halogenated silanes, epoxides, adipates, benzoates, carbon dioxide, dimethyldimethoxysilane, dimethyldichlorosilane, diethyladipate, and mixtures thereof. In embodiments, the use of coupling agents with three or more functional groups, with appropriate dosage levels, can provide coupling of (AB) n -X-(B-A') m where n and m have values ​​of 1, with a very small minority (less than 20 wt. % or less than 10 wt. %) having n and / or m with values ​​greater than 1.

[0029] In embodiments to increase the vinyl content of the conjugated diene portion of the SBC or to control the vinyl content of block B, the addition of a microstructure modifier and / or the control of the temperature of the addition and reaction are utilized in succession. Examples of modifiers include, but are not limited to, polar compounds such as ethers, amines, and other Lewis bases, and dialkyl ethers of glycols. The most preferred modifiers are selected from dialkyl ethers of ethylene glycol containing the same or different terminal alkoxy groups, optionally with alkyl substitution on the ethylene group, such as monoglyme, diglyme, diethoxyethane, 1,2-diethoxypropane, and 1-ethoxy-2,2-tert-butoxyethane, of which 1,2-diethoxypropane is most preferred.

[0030] Applications of styrenic block copolymers (SBC) The SBC in embodiments is for modifying bitumen to provide a polymer-modified bitumen (PMB) with improved physical properties compared to other types of block copolymers at the same polymer concentration (by weight), as discussed further below.

[0031] Preparation of PMB PMB compositions can be prepared by blending linear sequential SBC with bitumen and other suitable components. Any type of bitumen can be used to make PMB. This can be advantageous in situations where the quality, composition, or source of bitumen may vary. Various additives can be used in combination with the block copolymer to form the PMB composition. Examples include non-polymeric additives, non-reactive polymers, and reactive polymers. Non-polymeric additives include acid-based additives, flux oils, liquid plasticizers, hydrogen sulfide scavengers, amine scavengers, acid anhydrides, including linear and cyclic anhydrides; sulfur sources; and combinations thereof. Examples of acid-based additives include one or more of phosphorus acids and polyphosphoric acids.

[0032] Flax oil encompasses many types of oils used to modify asphalt and is the end product of crude oil distillation. Flax oil is a non-volatile oil that is blended with asphalt to soften it. Flax oil can be aromatic, paraffinic, or naphthenic. Flax oil can also be any renewable vegetable or bio-oil. Blends of two or more flax oils can also be used. Flax oil can also be a reclaimed oil, either mineral-derived or bio-derived.

[0033] In embodiments, the SBC and at least one base bitumen are first mixed, and then, optionally, a sulfur-based crosslinking agent is added to the mixture. Optionally, an acid-based additive may be introduced. The resulting mixture is blended at a temperature range of 140°C to 220°C, or above 150°C or below 200°C, to produce the PMB. High shear milling or low shear mixing processes known in the art may be used.

[0034] In embodiments, the PMB composition comprises 1 to 15 wt %, or 1 to 10 wt %, or 2 to 6 wt % SBC, based on the total weight of the PMB composition.

[0035] Use of PMB Compositions PMB is intended for use in applications including, but not limited to, asphalt paving and asphalt roofing. Examples include road paving materials for new pavements, pavement maintenance, and pavement repair in the form of hot mix asphalt, cold mix asphalt, warm mix asphalt, emulsified bitumen-based asphalt (chip seal, slurry seal, microseal, fog seal, among others), bituminous crack fillers, and tack coat layers.

[0036] PMB is also valuable for use in roofing applications, where it has relatively low viscosity, low penetration and a high softening point T spExamples include modified bituminous membranes, self-adhesive membranes, impact resistant shingles, laminates, shingle tab adhesives, shingle bodies, sheet or roll goods, and mopping or mastic asphalt applications.

[0037] Besides paving and roofing applications, other applications include, but are not limited to, pipe coatings, sealants, sound deadening membranes, carpets or railway construction.

[0038] Properties of polymer modified bitumen (PMB) For paving compositions, favorable MSCR %R is observed for PMBs made using linear sequential SBCs.

[0039] At a given wt% SBC in the PMB, the composition exhibits better MSCR properties than PMBs made using other types of prior art block copolymers, such as radial block copolymers or linear coupling block copolymers. Alternatively, the PMBs made can exhibit similar MSCR properties at lower polymer concentrations. Therefore, the PMBs have higher efficiency based on the amount of polymer.

[0040] PMB compositions have excellent properties due in part to the elastic modification of asphalt. One parameter that provides a measure of the effectiveness of the polymer in PMB is the "% recovery" (also referred to herein as "%R") under a given shear stress, measured using the MSCR (Multiple Stress Creep Recovery) test according to ASTM D7405 test method. The %R value is calculated using Eq(1): %R = 100 × (recoverable shear strain / peak strain) Eq(1) where the recoverable shear strain is given by the difference between the instantaneous shear strain and the irrecoverable shear strain. The MSCR test is also a standard method for evaluating the rutting resistance of asphalt mixes produced using PMB, especially at elevated temperatures. To compare the effectiveness of a given PMB versus a reference bituminous material, the parameter %R described above can be used.

[0041] This parameter can also be used to consider the effect of various variables on the overall performance of the PMB, such as the type of bitumen, the curing temperature or curing time used to prepare the PMB, and the weight percent of SBC in the PMB. Variations in bitumen can arise from a number of factors, such as the source of the bitumen, the process used to make the bitumen, and the composition of the bitumen (the components of the blend). When there is variability in bitumen grade, it is generally desirable to obtain a high %R value that does not vary too much with the bitumen chemistry and results in more stable performance under realistic road / pavement conditions and during road construction.

[0042] In embodiments, the produced PMB, after being crosslinked, exhibits an improvement in %R at 3.2 kPa and 64°C of at least 10%, or at least 12%, or at least 15%, or at least 20%, relative to a PMB having a linear coupled block copolymer ("comparative SBC") of molecular weight 173,000 g / mol, 10 mol% vinyl content, and 31% polystyrene content, measured at a polymer concentration of 3 wt% according to ASTM D7405.

[0043] The PMB produced also has a higher softening point T compared to PMB produced using other types of block copolymers. sp In embodiments, the PMB, after being crosslinked, has a softening point T that is at least 5° C. higher than that of a comparative SBC, measured according to the method of ASTM D36 at a polymer concentration of 9 wt. spIn embodiments, the PMB produced has a T (in degrees Celsius) that is at least 10° C. higher than a PMB having a linear sequential block copolymer with a MW of 150,000 g / mol, a vinyl content of 40%, and a polystyrene content of 30%, measured at a polymer concentration of 9% by weight according to ASTM D36. sp It has. [Example]

[0044] The following non-limiting examples are provided to illustrate the properties of linear sequential SBCs and PMBs made therefrom. "RTFO" stands for rotary thin film oven.

[0045] "DSR" means Dynamic Shear Rheometer.

[0046] "ODSR" stands for initial dynamic shear rheometry and indicates that testing is performed on unaged asphalt compositions using a dynamic shear rheometer.

[0047] "MSCR" stands for Multiple Stress Creep and Recovery. In the MSCR test, the parameter %R means the percentage of recoverable strain, and %R is used to evaluate the elastic recovery of polymer-modified bitumen.

[0048] "Jnr" means non-recoverable creep compliance.

[0049] "BBR m average" means the average m value measured using bending beam rheometry.

[0050] "BBR S average" means the average S value measured using bending beam rheometry.

[0051] ΔTc is given by the difference between the numerical value of the low continuous grade temperature (temperature at which stiffness S equals 300 MPa) determined from the bending beam rheometer (BBR) stiffness criterion and the low continuous grade temperature (temperature at which m equals 0.300) determined from the BBR m value.

[0052] G * .sin(δ) denotes the SuperPave fatigue parameter.

[0053] "PAV" stands for pressurized aging vessel, which is used to simulate the long-term aging of asphalt binders.

[0054] Example for preparing C260-2 block copolymer 34.5 kg of styrene was added to 1,032 kg of cyclohexane at 40-50°C, followed by 0.88 kg of 12% sec-butyllithium solution. The reaction was complete after 39 minutes. 169 kg of butadiene was then added over 58 minutes. The polymerization was allowed to proceed for 77 minutes. A second portion of 34.5 kg of styrene was then added over 10 minutes. The polymerization was allowed to proceed for 52 minutes, after which 63 grams of methanol was added to terminate the polymerization. After cooling the reaction mixture, 0.2 wt. % of a phenolic antioxidant, based on the polymer, was added for stabilization. The product, C260-2, was isolated by steam stripping to yield white crumbs.

[0055] Example block copolymers C260-8 and C275-1 These SBCs have the structure ABA', with the difference in MW of the A and A' blocks being 5,300 g / mol and 5,100 g / mol, respectively. They were prepared via the same procedure as above, except that diethoxypropane was added after the polymerization of styrene and before the addition of butadiene. The amounts and reaction conditions are listed in Table 1.

[0056] [Table 1]

[0057] In addition to the above SBCs, the following block copolymers (characterized in Table 2) were also used. These polymers have a similar MW to the polystyrene block.

[0058] U-119-X is a linear sequential block copolymer.

[0059] U-1101 is a linear triblock copolymer.

[0060] C246-8 is a radial block copolymer.

[0061] U-1184 is a branched triblock (radial) copolymer.

[0062] [Table 2]

[0063] Examples for preparing polymer-modified bitumen In the examples, each blend was made by mixing 2.5 wt. % of the milled form of the block copolymer and 97.5 wt. % of bitumen together under a nitrogen blanket in low shear mode at 180°C for 1 hour. After 1 hour, elemental sulfur was added at 0.1 wt. % of the bitumen and block polymer combination, and blending continued for an additional 6 hours at 180°C. The PMB blends were sampled for storage stability, RTFO DSR, and MSCR testing at 64°C. The results are shown in Table 3. The quantities "MSCR %R, 3.2 kPa, 64°C top layer" and "%R, 3.2 kPa, 64°C bottom layer" refer to the difference in %R between the top and bottom layers of the PMB blend, measured according to ASTM D7173. It is desirable for the PMB blend to have a low viscosity at 135°C, small separation (%R) top and bottom layer values ​​(negative or close to zero), a high RTFO DSR, and a high RTFO MSCR.

[0064] [Table 3]

[0065] All PMB samples had acceptable viscosities of less than 3.0 Pa.s at 135°C. PMB samples 9 and 10 showed no phase separation upon storage. Sample 8 showed some phase separation after storage. All PMBs exhibited high RTFO DSR properties. PMB sample 9 exhibited the best combination of viscosity, phase stability, and MSCR properties. PMBs with high MSCR properties (excellent elastomeric properties) may be valuable in paving applications. The use of PMBs with low viscosity or low block copolymer content may result in better performing roads overall and lead to material cost savings.

[0066] The block copolymers C260-8, U-119-X, U-1101, and U-1184 were compared for suitability in obtaining PMB formulations capable of passing the PG64E-22 / PG76-22 performance grade parameters. For each polymer sample, two PMB samples were prepared, one with 3 wt. % polymer and the other with 2 wt. % polymer. In each case, the PMB formulation was made by mixing the specified wt. % of the milled form of the polymer and bitumen together in low shear mode at 180°C for 1 hour under a nitrogen blanket. After 1 hour, 0.1 wt. % elemental sulfur was added, and blending was continued for 8 hours at 180°C. Storage stability was given by the difference in %R between the top and bottom layers of the PMB blend, measured according to ASTM D7173.

[0067] Standard:RTFO G * Interpolated polymer dosages based on / sin(δ), 76°C = 2.2 kPa and Jnr, 3.2 kPa, 64°C < 0.5 are shown in Table 5.

[0068] The data show that PMB compositions based on the block copolymer of SBC block copolymer C260-8 have better properties than those made using block copolymers U-119-X, U-1101, and U-1184. For example, PMB composition 14 is more efficient, based on weight percent of block copolymer, than PMB compositions 16, 18, and 20 in achieving favorable MSCR %R.

[0069] [Table 4]

[0070] [Table 5]

[0071] The interpolated data shows that the PMB obtained using block copolymer C260-8 exhibited the most favorable overall performance at the lowest wt% loading in the asphalt compared to the next best polymer, polymer example U-119-X.

[0072] Block copolymer C260-8 forms PMBs with excellent MSCR properties, even when the binder component of the bitumen is varied. Block copolymers C260-8 and U-1101 were selected for this study. For each polymer sample, two PMB samples were prepared, one with 3 wt.% polymer and the other with 2 wt.% polymer, using the same procedure as previously described. Criteria: RTFO G * Interpolated polymer dosages were determined based on / sin(δ), 76°C = 2.2 kPa and Jnr, 3.2 kPa, 64°C < 0.5. The data are shown in Tables 6 and 7.

[0073] [Table 6]

[0074] [Table 7]

[0075] Table 8 shows the ring-and-ball T of PMBs made using polymers C260-8, U-1101, and U-1184. sp At a given weight percent of polymer, the PMB made using polymer C260-8 exhibits the highest ring-and-ball T sp The linear sequential block copolymer C260-8 had high ring-ball T sp PMBs with

[0076] [Table 8]

[0077] Table 8 also shows that at a given wt% of polymer, the PMB based on polymer C260-8 exhibits a higher T than the PMB samples based on block copolymers U-1101 and U-119-X, in addition to showing an improvement in %R (see Table 4). sp Therefore, the PMB based on the block copolymer C260-8 has a high efficiency per unit weight of polymer.

[0078] The comparative performance of block copolymers C260-8, U-119-X and U-1101 was also studied in relation to different bitumen grades A, B and C. All blends were made under the conditions listed in Table 9.

[0079] [Table 9]

[0080] The properties of PMBs 26-37 made from polymers C260-8, U-119-X and U-1101 are shown in Table 10. For different bitumen grades, PMBs made from polymer C260-8 provide relatively low viscosity while maintaining satisfactory penetration, T sp The percent phase separation was measured as follows: Freshly prepared PMB was poured into a 1 L metal can. The can was then covered with a lid and placed in a 160°C oven for 5 days. The sample was then removed and rapidly cooled to room temperature to solidify the PMB sample. The bottom of the metal can was then removed, and the sides of the can were heated until the PMB sample inside the can slid out. The PMB sample was probed with a needle from bottom to top to detect whether phase separation of the polymer in the sample had occurred (in a phase-separated sample, the polymer floats toward the top of the sample, and the physical properties of the top and bottom portions change significantly). The sample was then sliced ​​with a hot knife at a height that separated the polymer-rich and polymer-poor sections. The polymer-rich section of the sample was weighed, and this weight was divided by the total weight of the sample to convert to a percentage. 100% polymer rich indicates that the polymer remained completely dispersed throughout the sample. 50% phase separation indicates that the polymer-rich phase makes up 50% of the total sample weight after the test is completed. 100% polymer-rich is the desired test result.

[0081] [Table 10]

[0082] The data show that all three blends have relatively equal penetration and relatively low viscosity, but the PMB of Example 26 has the highest T sp PMB Composition 26 exhibits a unique balance of T sp , penetration and viscosity.

[0083] Although the terms "comprising" and "including" are used herein to describe various embodiments, the terms "consisting essentially of" and "consisting of" may be used in place of "comprising" and "including" to provide more specific embodiments of the disclosure, and are disclosed.

Claims

1. A polymer-modified bitumen composition comprising: At least with bitumen, a block copolymer in an amount of 1 to 25% by weight relative to the total weight of the composition; Including, The block copolymer is A - B - A' or (A - B) ｎ - X - (B - A') ｍ (In the formula, A and A' are vinyl aromatic blocks having different peak molecular weights, the difference in peak molecular weights being in the range of 3,000 to 8,000 g / mol; B is a conjugated diene block; B has an average vinyl content in the range of 20 to 60 mol %; n and m are each independently 1 or greater, and X is a coupling agent. and has the formula The block copolymer is a polystyrene content of 20 to 35% by weight, based on the total weight of the block copolymer; A peak molecular weight of 200,000 to 300,000 g / mol; and the polymer-modified bitumen composition, after being crosslinked, has a percent recovery (%R) of at least 10% at 3.2 kPa and 64°C for a polymer-modified bitumen having a peak molecular weight of 173,000 g / mol, a 10 mol% vinyl content, and a 31% polystyrene content linear coupled block copolymer, measured at a polymer concentration of 3 wt% according to ASTM D7405; composition.

2. Formula (A-B) ｎ -X-(B-A') ｍ 10. The polymer modified bitumen composition of claim 1, having the formula: wherein n and m each independently have a value of 1.

3. The block copolymer has the formula (A-B): ｎ -X-(B-A') ｍ 3. The polymer modified bitumen composition of claim 1 or 2, having the formula: wherein n and m each independently have a value greater than 1 and less than or equal to 5.

4. 3. The polymer modified bitumen composition of claim 1 or 2 having a peak molecular weight of 220,000 to 270,000 g / mol.

5. 3. The polymer modified bitumen composition according to claim 1 or 2, wherein block B has a vinyl content of 25 to 55 mol %, the vinyl content being distributed uniformly or in a gradient throughout the conjugated diene block B.

6. A polymer-modified bitumen composition as described in claim 1 or 2, wherein the vinyl content is distributed in one or more distinct blocks with a vinyl content of less than 20% or greater than or equal to 22% in the conjugated diene block B.

7. 3. The polymer modified bitumen composition of claim 1 or 2 produced by sequential anionic polymerization or sequential anionic polymerization followed by coupling.

8. 8. The polymer modified bitumen composition of claim 7 having the formula ABA' and produced by sequential anionic polymerization.

9. Formula (A-B) ｎ -X-(B-A') ｍ 8. The polymer modified bitumen composition of claim 7, wherein the polymer modified bitumen composition has the formula:

10. 10. The polymer modified bitumen composition of claim 9, wherein the coupling agent is selected from the group consisting of methoxysilanes, halogenated silanes, epoxides, adipates, benzoates, carbon dioxide, dimethyldimethoxysilane, dimethyldichlorosilane, diethyladipate, and mixtures thereof.

11. 8. The polymer modified bitumen composition according to claim 7, wherein at least a microstructure modifier is added to the polymerization process to control the vinyl content of block B, said microstructure modifier being selected from ethers, amines, dialkyl ethers of glycols and mixtures thereof.

12. 3. The polymer modified bitumen composition of claim 1 or 2 used in an asphalt paving product or an asphalt roofing product.

13. 3. The polymer modified bitumen composition of claim 1 or 2, used in new pavement, pavement maintenance, pavement repair, hot mix asphalt, cold mix asphalt, warm mix asphalt, emulsified bitumen-based asphalt, modified bitumen membrane, self-adhesive membrane, impact resistant roofing shingles, laminates, roofing shingle tab adhesives, roofing shingle bodies, sheets, rolls, pipe coatings, sealants, sound deadening membranes, carpets, railway construction, crack fillers, chip seals and microsurfacing.

Images