ASPHALT COMPOSITION COMPRISING A MIXTURE OF AN ISOCYANATE AND A POLYMER AS PERFORMANCE ADDITIVES

Abstract

An asphalt composition comprising 0.1 to 8 wt.-% based on the total weight of the composition of an Isocyanate as thermosetting reactive compound and 0.1 to 8 wt.-% based on the total weight of the composition of a polymer selected from the group consisting of styrene/butadiene/styrene copolymer (SBS), styrene butadiene rubber (SBR), neoprene, polyethylene, low density polyethylene, oxidized high density polyethylene, polypropylene, oxidized high density polypropylene, maleated polypropylene, ethylene-butyl-acrylate-glycidyl-methacrylate terpolymer, ethyl vinyl acetate (EVA) and polyphosphoric acid (FRA).

Claims

1.-20. (canceled)

21. An asphalt composition comprising 0.1 to 8 wt.-% based on the total weight of the composition of an Isocyanate as thermosetting reactive compound and 0.1 to 8 wt.-% based on the total weight of the composition of a polymer selected from the group consisting of styrene/butadiene/styrene copolymer (SBS), styrene butadiene rubber (SBR), neoprene, polyethylene, low density polyethylene, oxidized high density polyethylene, polypropylene, oxidized high density polypropylene, maleated polypropylene, ethylene-butyl-acrylate-glycidyl-methacrylate terpolymer, ethyl vinyl acetate (EVA) and polyphosphoric acid (PPA).

22. The asphalt composition according to claim 21, wherein the isocyanate has a functionality of at least 2.0.

23. The asphalt composition according to claim 21, wherein the isocyanate is selected from the group consisting of monomeric MDI, polymeric MDI, MDI prepolymers, TDI and HDI.

24. The asphalt composition according to claim 21, wherein the isocyanate is polymeric MDI.

25. The asphalt composition according to claim 24, wherein the polymeric MDI has a viscosity in the range of from 10 to 5000 cps/mPas at 25° C.

26. The asphalt composition according to claim 24, wherein the amount of polymeric MDI is of from 0.5 to 5.0 wt.-% based on the total weight of the composition.

27. The asphalt composition according to claim 21, wherein the polymer is a styrene/butadiene/styrene copolymer (SBS).

28. The asphalt composition according to claim 27, wherein the styrene/butadiene/styrene copolymer (SBS) is linear.

29. The asphalt composition according to claim 27, wherein the styrene/butadiene/styrene copolymer (SBS) has a styrene content of from 25 to 40 wt.-% based on the total weight of the polymer.

30. The asphalt composition according to claim 27, wherein the amount of styrene/butadiene/styrene copolymer (SBS) is of from 0.8 to 3.0 wt.-% based on the total weight of the composition.

31. The asphalt composition according to claim 21, wherein the polymer is polyphosphoric acid (PPA).

32. The asphalt composition according to claim 31, wherein the polyphosphoric acid (PPA) has a calculated H.sub.3PO.sub.4 content in the range of from 100 to 120%.

33. The asphalt composition according to claim 31, wherein the polyphosphoric acid (PPA) is water-free.

34. The asphalt composition according to claim 31, wherein the amount of polyphosphoric acid (PPA) is of from 0.8 to 2.0 wt.-% based on the total weight of the composition.

35. A process for the preparation of an asphalt composition according to claim 21 comprising the following steps: a) Heating up the starting asphalt to a temperature of from 110 to 190° C. b) Adding the desired amount of isocyanate and the respective polymer under stirring, wherein the order of adding the desired additives is not decisive c) After step b) the reaction mixture is stirred at a temperature in the range of from 110 to 190° C. d) The end of the reaction is determined by IR spectroscopy wherein the reaction is under an oxygen atmosphere.

36. A process according to claim 35, wherein the temperature is in the range of from 110 to 165° C.

37. A process according to claim 35, wherein the temperature in step a) and step c) are the same and in the range of from 110 to 165° C.

38. A process according to claim 35, wherein the temperature is in the range of from 110 to 165° C. and the reaction mixture is stirred for at least 2 h after the addition step b).

39. A process according to claim 35, wherein the end of the reaction is determined by IR spectroscopy.

40. A method comprising providing the asphalt composition according to claim 21 and preparing an asphalt mix composition.

Description

EXAMPLES AND COMPARATIVE EXAMPLES

[0104] General procedure for the preparation of an asphalt composition, blend 1 to 10

[0105] Paving-type asphalt binder compositions comprising asphalt and various polymer blends, as specified below in table 1 and 2, were prepared and subjected to experimental steps to determine their performance.

[0106] The general procedure used to formulate was as follow: (a) heating up the starting asphalt to a temperature up to 140° C. under oxygen atmosphere and under 250 to 400 rpm with a low shear mixer in an oil bath (temperature set up at 150° C.). (b) When the internal temperature of at least 140° C. was reached, polymeric additive was slowly added into the asphalt sample within a 2 minutes period. (c) The asphalt sample was stirred for 30 minutes. (d) The isocyanate was then added to the asphalt sample containing the polymer and mixed further. The reaction was followed by infrared until the isocyanate band is reached an absorption value below 150.

[0107] The samples were dispatched into cans before further testing and cooled down to room temperature.

[0108] Thermosetting reactive compound used in the Examples is a pMDI having a functionality of 2.7 named in the following As20.

[0109] The test specimens from blend 1 to 5 were prepared and tested according to AASHTO M320 (Table 1). The test specimen from blend 6 to 10 were prepared and tested according to the penetration grade system and European norms (Table 2). The values of the examples are detected according to the respective DIN regulation.

[0110] pMDI with respective functionality are commercially available for example at the following companies: Bayer, BASF SE, Huntsmann etc.

[0111] Detailed Description of the Used Method:

[0112] Asphalt Tests

[0113] Softening Point DIN EN 1427

[0114] 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 (25±0.4) [mm].

[0115] Rolling Thin Film Oven Test DIN EN 12607-1

[0116] Bitumen is heated in bottles in an oven for 85 [min] at 163[° C.]. The bottles are rotated at 15 [rpm] and heated air is blown into each bottle at its lowest point of travel at 4000 [mL/min]. The effects of heat and air are determined from changes in physical test values as measured before and after the oven treatment.

[0117] Pressure Aging Vessel DIN EN 14769

[0118] The residue from the RTFOT is placed in standard stainless-steel pans and aged at a specified conditioning temperature (90[° C.], 100[° C.] or 110[° C.]) for 20 [h] in a vessel pressurized with air to 2.10 [MPa]. The temperature is selected according to the grade of the asphalt binder (application). Finally, the residue is vacuum degassed.

[0119] Dynamic Shear Rheometer (DSR) DIN EN 14770-ASTM D7175

[0120] A dynamic shear rheometer test system consists of parallel plates, a means for controlling the temperature of the test specimen, a loading device, and a control and data acquisition system.

[0121] Temperature Sweep DIN EN 14770

[0122] This test has the objective of measuring the complex shear modulus and phase angle (δ) of asphalt binders. The test consists in pressing an 8 or 25 [mm] diameter test specimen between parallel metal plates at a defined frequency and temperature. One of the parallel plates is oscillated with respect to the other at, in this case, 1.59 [Hz] and angular deflection amplitudes. The required amplitudes must be selected so that the testing is within the region of linear behavior. This is repeated at 30, 40, 50, 60, 70, 80 and 90[° C.].

[0123] Multiple Stress Creep Recovery (MSCR) Test DIN EN 16659-ASTM D7405

[0124] This test method is used to determine the presence of elastic response after short term aging in an asphalt binder under shear creep and recover at two stress level (0.1 and 3.2 [kPa]) and at a specified temperature (50 [° C.]). This test uses the DSR to load a 25 [mm] at a constant stress for 1 [s], and then allowed to recover for 9 [s]. Ten creep and recovery cycles are run at 0.100 [kPa] creep stress followed by ten cycles at 3.200 [kPa] creep stress.

[0125] Elastic Recovery DIN EN 13398

[0126] A bituminous binder specimen (virgin) is stretched at the test temperature and a constant rate of 50 mm/min to a predetermined elongation (200 mm). The bitumen thread thus produced is cut in the middle to obtain two half-threads. After a predetermined time of 30 min for recovery has elapsed, the shortening of the half-threads is measured and expressed as the percentage of the elongation length. This procedure is typically performed at a test temperature of 25° C.

[0127] Bending Beam Rheometer DIN EN 14771-ASTM D6648

[0128] This test is used to measure the mid-point deflection of a simply supported prismatic beam of asphalt binder subjected to a constant load applied to its mid-point. A prismatic test specimen is placed in a controlled temperature fluid bath and loaded with a constant test load for 240 [s]. The test load (980±50 [mN]) and the mid-point deflection of the test specimen are monitored versus time using a computerized data acquisition system. The maximum bending stress at the midpoint of the test specimen is calculated from the dimensions of the test specimen, the distance between supports, and the load applied to the test specimen for loading times of 8.0, 15.0, 30.0, 60.0, 120.0 and 240.0 [s]. The stiffness of the test specimen for the specific loading times is calculated by dividing the maximum bending stress by the maximum bending strain.

TABLE-US-00001 TABLE 1 Asphalt compositions of blend 4 to 5 and of the comparative blends 1 to 3 as well as pure asphalt as control, composition and physical properties. Blend 1 Blend 2 Blend 3 Comparative Comparative Comparative Blend Blend Composition Control 1 2 3 4 5 PG 58-28 100% 98% 97% 98% 95% 96% As20  2%  2%  2% SBS  3%  3% PPA  2%  2% Total additive  2%  3%  2%  5%  4% loading Jnr (0.1 kPa) 3.134 0.633 0.146 1.599 0.000 0.065 Jnr (3.2 kPa) 3.524 0.829 0.244 1.964 0.000 0.124 MSCR (% 3 27 82 12 >99 3 recovery, 0.1 kPa) MSCR (% 0.5 12 72 77 >99 57 recovery, 3.2 kPa) RTFO High 60.0 69.2 69.8 63.8 89.6 79.2 temperature (° C.) Low temperature −29.8 −29.3 −31.1 −26.7 −30.8 −23.7 (° C.) UTI 89 98.5 100.8 90.5 120.4 102.4 SHRP Grade 58-28 64-28 64-28 58-22 88-28 76-22 Grade jump +1 +1 −1 +5 +3

TABLE-US-00002 TABLE 2 Asphalt compositions of blend 9 to 10 and of the comparative blends 6 to 8 as well as pure asphalt as control, composition and physical properties of the respective asphalt compositions. Blend 6 Blend 7 Blend 8 Comparative Comparative Comparative Blend Blend Composition Control 6 7 8 9 10 Pen 50/70 100% 98% 99% 97% 98% 97% As20  2%  1%  2% SBS  1%  3%  1%  1% Total additive  2%  1%  3%  2%  3% loading Softening Point 50.8 58.0 52.2 54.6 55.2 61.2 (° C.) G* in Pa at 60° C. — — 4769 7537 9175 15879 MSCR (% −0.7 45.1 12.4 35.4 30.8 63.4 recovery, 0.1 kPa) MSCR (% −3.5 29.0 8.2 19.2 16.4 53.8 recovery, 3.2 kPa) Phase angle (δ) — 75 83.1 77.1 78.2 71.1 in ° at 60° C. Elastic recovery at — 15 25 50 35 50 25° C.

[0129] The asphalt modification according to the invention is leading to an improved performance with a severe increase of the useful temperature interval, an increased elastic response, a drastic decrease of the non-recoverable creep compliance (Jnr). The combination of isocyanate and polymer as additive in an asphalt resulting in a synergetic effect, which can clearly be shown by the examples of the present invention in table 1 and table 2.