USH1484H - Method for obtaining polymer/bitumen blends with improved stability and polymer efficiency - Google Patents
Method for obtaining polymer/bitumen blends with improved stability and polymer efficiency Download PDFInfo
- Publication number
- USH1484H USH1484H US08/160,005 US16000593A USH1484H US H1484 H USH1484 H US H1484H US 16000593 A US16000593 A US 16000593A US H1484 H USH1484 H US H1484H
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- United States
- Prior art keywords
- polymer
- bitumen
- weight percent
- mixing
- minutes
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
- 239000000203 mixture Substances 0.000 title claims abstract description 25
- 239000010426 asphalt Substances 0.000 title claims abstract description 24
- 238000000034 method Methods 0.000 title claims abstract description 19
- 229920000642 polymer Polymers 0.000 title claims description 26
- 238000002156 mixing Methods 0.000 claims abstract description 17
- 229920001400 block copolymer Polymers 0.000 claims abstract description 14
- 150000001993 dienes Chemical class 0.000 claims abstract description 13
- 230000008569 process Effects 0.000 claims abstract description 13
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims abstract description 12
- 229910052717 sulfur Inorganic materials 0.000 claims abstract description 12
- 239000011593 sulfur Substances 0.000 claims abstract description 12
- 229920001577 copolymer Polymers 0.000 claims abstract description 10
- -1 vinyl aromatic hydrocarbon Chemical class 0.000 claims abstract description 10
- 238000013019 agitation Methods 0.000 claims abstract description 9
- 229920002554 vinyl polymer Polymers 0.000 claims abstract description 8
- 230000006872 improvement Effects 0.000 claims abstract description 5
- 239000000463 material Substances 0.000 description 7
- 238000005984 hydrogenation reaction Methods 0.000 description 5
- KAKZBPTYRLMSJV-UHFFFAOYSA-N Butadiene Chemical compound C=CC=C KAKZBPTYRLMSJV-UHFFFAOYSA-N 0.000 description 4
- RRHGJUQNOFWUDK-UHFFFAOYSA-N Isoprene Chemical compound CC(=C)C=C RRHGJUQNOFWUDK-UHFFFAOYSA-N 0.000 description 4
- PPBRXRYQALVLMV-UHFFFAOYSA-N Styrene Chemical compound C=CC1=CC=CC=C1 PPBRXRYQALVLMV-UHFFFAOYSA-N 0.000 description 4
- 239000003054 catalyst Substances 0.000 description 4
- 229920001971 elastomer Polymers 0.000 description 4
- 239000005060 rubber Substances 0.000 description 4
- 238000006243 chemical reaction Methods 0.000 description 3
- 239000000178 monomer Substances 0.000 description 3
- 230000000704 physical effect Effects 0.000 description 3
- 229920000468 styrene butadiene styrene block copolymer Polymers 0.000 description 3
- SDJHPPZKZZWAKF-UHFFFAOYSA-N 2,3-dimethylbuta-1,3-diene Chemical compound CC(=C)C(C)=C SDJHPPZKZZWAKF-UHFFFAOYSA-N 0.000 description 2
- KDLHZDBZIXYQEI-UHFFFAOYSA-N Palladium Chemical compound [Pd] KDLHZDBZIXYQEI-UHFFFAOYSA-N 0.000 description 2
- ATUOYWHBWRKTHZ-UHFFFAOYSA-N Propane Chemical compound CCC ATUOYWHBWRKTHZ-UHFFFAOYSA-N 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 238000007334 copolymerization reaction Methods 0.000 description 2
- 238000004132 cross linking Methods 0.000 description 2
- 230000002950 deficient Effects 0.000 description 2
- 239000006185 dispersion Substances 0.000 description 2
- 238000009826 distribution Methods 0.000 description 2
- 239000000284 extract Substances 0.000 description 2
- 230000002427 irreversible effect Effects 0.000 description 2
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 description 2
- AHAREKHAZNPPMI-AATRIKPKSA-N (3e)-hexa-1,3-diene Chemical compound CC\C=C\C=C AHAREKHAZNPPMI-AATRIKPKSA-N 0.000 description 1
- PMJHHCWVYXUKFD-SNAWJCMRSA-N (E)-1,3-pentadiene Chemical compound C\C=C\C=C PMJHHCWVYXUKFD-SNAWJCMRSA-N 0.000 description 1
- OEVVKKAVYQFQNV-UHFFFAOYSA-N 1-ethenyl-2,4-dimethylbenzene Chemical compound CC1=CC=C(C=C)C(C)=C1 OEVVKKAVYQFQNV-UHFFFAOYSA-N 0.000 description 1
- NVZWEEGUWXZOKI-UHFFFAOYSA-N 1-ethenyl-2-methylbenzene Chemical compound CC1=CC=CC=C1C=C NVZWEEGUWXZOKI-UHFFFAOYSA-N 0.000 description 1
- UVHXEHGUEKARKZ-UHFFFAOYSA-N 1-ethenylanthracene Chemical compound C1=CC=C2C=C3C(C=C)=CC=CC3=CC2=C1 UVHXEHGUEKARKZ-UHFFFAOYSA-N 0.000 description 1
- QEDJMOONZLUIMC-UHFFFAOYSA-N 1-tert-butyl-4-ethenylbenzene Chemical compound CC(C)(C)C1=CC=C(C=C)C=C1 QEDJMOONZLUIMC-UHFFFAOYSA-N 0.000 description 1
- JLBJTVDPSNHSKJ-UHFFFAOYSA-N 4-Methylstyrene Chemical compound CC1=CC=C(C=C)C=C1 JLBJTVDPSNHSKJ-UHFFFAOYSA-N 0.000 description 1
- 239000004215 Carbon black (E152) Substances 0.000 description 1
- XDTMQSROBMDMFD-UHFFFAOYSA-N Cyclohexane Chemical compound C1CCCCC1 XDTMQSROBMDMFD-UHFFFAOYSA-N 0.000 description 1
- VGGSQFUCUMXWEO-UHFFFAOYSA-N Ethene Chemical compound C=C VGGSQFUCUMXWEO-UHFFFAOYSA-N 0.000 description 1
- 239000005977 Ethylene Substances 0.000 description 1
- 239000004606 Fillers/Extenders Substances 0.000 description 1
- UFHFLCQGNIYNRP-UHFFFAOYSA-N Hydrogen Chemical compound [H][H] UFHFLCQGNIYNRP-UHFFFAOYSA-N 0.000 description 1
- 229920002633 Kraton (polymer) Polymers 0.000 description 1
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 1
- 239000004698 Polyethylene Substances 0.000 description 1
- 239000007868 Raney catalyst Substances 0.000 description 1
- 229910000564 Raney nickel Inorganic materials 0.000 description 1
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 1
- XYLMUPLGERFSHI-UHFFFAOYSA-N alpha-Methylstyrene Chemical compound CC(=C)C1=CC=CC=C1 XYLMUPLGERFSHI-UHFFFAOYSA-N 0.000 description 1
- 125000003118 aryl group Chemical group 0.000 description 1
- FACXGONDLDSNOE-UHFFFAOYSA-N buta-1,3-diene;styrene Chemical compound C=CC=C.C=CC1=CC=CC=C1.C=CC1=CC=CC=C1 FACXGONDLDSNOE-UHFFFAOYSA-N 0.000 description 1
- 125000004432 carbon atom Chemical group C* 0.000 description 1
- 239000011280 coal tar Substances 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005336 cracking Methods 0.000 description 1
- 239000003431 cross linking reagent Substances 0.000 description 1
- 230000007812 deficiency Effects 0.000 description 1
- 229920000359 diblock copolymer Polymers 0.000 description 1
- 229920003244 diene elastomer Polymers 0.000 description 1
- 239000003085 diluting agent Substances 0.000 description 1
- 238000004821 distillation Methods 0.000 description 1
- 239000000945 filler Substances 0.000 description 1
- 229930195733 hydrocarbon Natural products 0.000 description 1
- 150000002430 hydrocarbons Chemical class 0.000 description 1
- 229910052739 hydrogen Inorganic materials 0.000 description 1
- 239000001257 hydrogen Substances 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000002480 mineral oil Substances 0.000 description 1
- 235000010446 mineral oil Nutrition 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 239000003607 modifier Substances 0.000 description 1
- 229920006030 multiblock copolymer Polymers 0.000 description 1
- 229910000510 noble metal Inorganic materials 0.000 description 1
- 239000003921 oil Substances 0.000 description 1
- 230000003647 oxidation Effects 0.000 description 1
- 238000007254 oxidation reaction Methods 0.000 description 1
- 229910052763 palladium Inorganic materials 0.000 description 1
- 230000035515 penetration Effects 0.000 description 1
- 239000003208 petroleum Substances 0.000 description 1
- 239000003209 petroleum derivative Substances 0.000 description 1
- PMJHHCWVYXUKFD-UHFFFAOYSA-N piperylene Natural products CC=CC=C PMJHHCWVYXUKFD-UHFFFAOYSA-N 0.000 description 1
- 239000004033 plastic Substances 0.000 description 1
- 229920003023 plastic Polymers 0.000 description 1
- 229910052697 platinum Inorganic materials 0.000 description 1
- 229920001084 poly(chloroprene) Polymers 0.000 description 1
- 229920001200 poly(ethylene-vinyl acetate) Polymers 0.000 description 1
- 229920000573 polyethylene Polymers 0.000 description 1
- 229920002959 polymer blend Polymers 0.000 description 1
- 238000006116 polymerization reaction Methods 0.000 description 1
- 229920000346 polystyrene-polyisoprene block-polystyrene Polymers 0.000 description 1
- 238000001556 precipitation Methods 0.000 description 1
- 238000002360 preparation method Methods 0.000 description 1
- 239000001294 propane Substances 0.000 description 1
- 230000009257 reactivity Effects 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 230000035945 sensitivity Effects 0.000 description 1
- 238000003860 storage Methods 0.000 description 1
- 239000011115 styrene butadiene Substances 0.000 description 1
- 229920003048 styrene butadiene rubber Polymers 0.000 description 1
- 239000000126 substance Substances 0.000 description 1
- 239000010936 titanium Substances 0.000 description 1
- 229910052719 titanium Inorganic materials 0.000 description 1
- 229910052723 transition metal Inorganic materials 0.000 description 1
- 150000003624 transition metals Chemical class 0.000 description 1
Classifications
-
- C—CHEMISTRY; METALLURGY
- C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
- C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
- C08L95/00—Compositions of bituminous materials, e.g. asphalt, tar, pitch
Definitions
- the present invention relates to a process for blending block copolymers of vinyl aromatic hydrocarbons and conjugated dienes with bitumen and crosslinking them with sulfur. More particularly, the present invention relates to such a process which utilizes high shear mixing.
- Asphalt is a common material utilized for the preparation of paving and roofing materials and also for coatings such as pipe coatings and tank liners. While the material is suitable in many respects, it inherently is deficient in some physical properties which it would be highly desirable to improve. Efforts have been made in this direction by addition of certain conjugated diene rubbers, ethylene containing plastics like EVA and polyethylene, neoprene, resins, fillers and other materials for the modification of one or more of the physical properties of the asphalt. Each of these added materials modifies the asphalt in one respect or another but certain deficiencies can be noted in all modifiers proposed.
- some of them have excellent weather resistance, sealing and bonding properties but are often deficient with respect to warm tack, modulus, hardness and other physical properties; and some of them improve only the high temperature performance of asphalt, some only improve the low temperature performance of asphalt, while some lack thermal stability or mixing stability with asphalt.
- diene polymer rubbers such as styrenebutadiene rubber and styrene-rubber block copolymers such as styrene-butadiene-styrene and styrene-isoprene-styrene block copolymers have been used to dramatically improve the thermal and mechanical properties of asphalts. Practical application of the rubber addition approach requires that the blended product retain improved properties and homogeneity during transportation, storage and processing. Long term performance of elastomer-modified asphalts also depends on the ability of the blend to maintain thermal and chemical stability.
- Such bitumen/block copolymer mixtures have been crosslinked with a crosslinking agent such as sulfur to provide improved mechanical properties.
- a crosslinking agent such as sulfur
- a number of methods for incorporating the sulfur have been used. One of these involves mixing the bitumen and the copolymer together and agitating them for a period of time before adding the sulfur. After the sulfur is added, the agitation is continued for a period of time.
- This method is advantageous but has the disadvantage that the resulting morphology is relatively coarse. A very fine dispersion of the polymer would provide better high temperature properties. Therefore, it would be advantageous to provide a process for producing such bitumen/block copolymer blends which have a stable and very fine morphology.
- the present invention provides such a process.
- the present invention is an improvement in a process for producing a blend of bitumen and a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene which comprises mixing from 88 to 99.5 weight percent of bitumen with 0.5 to 12 weight percent of copolymer at 135° to 250° C., agitating the mixture for at least 30 minutes, adding 0.01 to 2 percent sulfur to the mixture and maintaining the mixture under agitation for at least 30 minutes.
- the improvement comprises utilizing high shear mixing at a shear rate of at least 10,000 second -1 to provide the agitation.
- bituminous component in the bituminous-polymer compositions according to the present invention may be a naturally occurring bitumen or derived from a mineral oil.
- petroleum derivatives obtained by a cracking process, pitch and coal tar can be used as the bituminous component as well as blends of various bituminous materials.
- suitable components include distillation or "straight-run bitumens", precipitation bitumens, e.g. propane bitumens, blown bitumens and mixtures thereof.
- Other suitable bituminous components include mixtures of one or more of these bitumens with extenders such as petroleum extracts, e.g. aromatic extracts, distillates or residues, or with oils.
- the block copolymers may be produced by any well known block polymerization or copolymerization procedures including the well-known sequential addition of monomer techniques, incremental addition of monomer technique or coupling technique.
- tapered copolymer blocks can be incorporated in the multiblock copolymer by copolymerizing a mixture of conjugated diene and vinyl aromatic hydrocarbon monomers utilizing the difference in their copolymerization reactivity rates.
- the manufacture of such polymers is described in U.S. Patent Nos. 3,113,986, 4,226,952, and Reissue 27,145, the disclosures of which are herein incorporated by reference.
- the polymers used herein may be linear polymers, radial polymers having three or more arms, and they may also be star polymers having a plurality of arms.
- the arms referred to are block copolymers of vinyl aromatic hydrocarbons and conjugated dienes.
- Conjugated dienes which may be utilized to prepare the polymers and copolymers include those having from 4 to 8 carbon atoms and also include 1,3-butadiene, 2-methyl-l,3-butadiene(isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and the like. Mixtures of such conjugated dienes may also be used.
- the preferred conjugated dienes are 1,3-butadiene and isoprene.
- Vinyl aromatic hydrocarbons which may be utilized to prepare copolymers include styrene, o-methylstyrene, p-methylstyrene, p-tertbutylstyrene, 2,4-dimethylstyrene, alpha-methylstyrene, vinylnapthalene, vinylanthracene and the like.
- the preferred vinyl aromatic hydrocarbon is styrene.
- the present invention works with both unhydrogenated and hydrogenated polymers. Hydrogenated ones are useful in certain circumstances. While unhydrogenated diene polymers have a number of outstanding technical advantages, one of their principal limitations lies in their sensitivity to oxidation. This can be minimized by hydrogenating the copolymers, especially in the diene blocks.
- the hydrogenation of these polymers and copolymers may be carried out by a variety of well established processes including hydrogenation in the presence of such catalysts as Raney Nickel, noble metals such as platinum, palladium and the like and soluble transition metal catalysts. Titanium biscyclopentadienyl catalysts may also be used.
- Suitable hydrogenation processes which can be used are ones wherein the diene-containing polymer or copolymer is dissolved in an inert hydrocarbon diluent such as cyclohexane and hydrogenated by reaction with hydrogen in the presence of a soluble hydrogenation catalyst.
- an inert hydrocarbon diluent such as cyclohexane
- the polymers are hydrogenated in such a manner as to produce hydrogenated polymers having a residual unsaturation content in the polydiene block of less than about 20%, and preferably as close to zero percent as possible, of their original unsaturation content prior to hydrogenation.
- bitumen/block copolymer compositions of the present invention generally comprise from 88 to 99.5, preferably 92 to 99, weight percent asphalt and 0.5 to 12, preferably 1 to 8, weight percent block copolymer. Higher polymer concentrations provide good properties but are not cost effective. Lower polymer concentrations do not provide a continuous polymer network necessary for improved properties. These two materials are mixed together and then subjected to high shear mixing at 135° to 250° C. at a shear rate of at least 10,000 second -1 for a period of at least 30 minutes in order to achieve a blend morphology characterized by a very fine, stable polymer distribution.
- sulfur is added in an amount of 0.01 to 2 weight percent and the mixture is maintained under said high shear agitation for at least 30 minutes to achieve complete reaction of the sulfur.
- the irreversible crosslinking reaction stabilizes the dispersion achieved by the high shear mixing.
- the high shear rate specified above for the agitation of the bitumen/polymer blend is necessary to achieve the desired morphology and to assure a stable irreversible fine polymer distribution.
- Shear rate is defined as the ratio of the speed of the moving part of the mixer or rotor to the gap between the moving part and stationary part or stator of the mixer. For example, a 3 foot diameter impeller rotating at 100 rpm with a clearance of 1/2 inch would provide a shear rate of about 400 second -1 .
- a Silverson L4R mixer with a diameter of 30 millimeters and a gap of approximately 0.1 millimeter rotating at 3000 rpm would provide a shear rate of about 50,000 second -1 .
- Shear rates suitable to this invention may be achieved on a laboratory scale with mixers manufactured by, for example, Silverson or Ross, and on a commercial scale with mixers manufactured by, for example, Siefer or Dalworth. A shear rate of at least 10,000 second -1 is required to achieve the desired morphology of the invention.
- Polymer and asphalt as specified below were mixed at 160° C. for 1 1/2 hours using high or low shear mixing.
- high shear mixing a Silverson L4R mixer operating at 4000 rpm (greater than 750,000 second -1 ) was used.
- low shear mixing an impeller low shear mixer operating at 1000 rpm (about 000 second -1 ) was used.
- sulfur was added and mixed an additional hour. High shear mixing leads to significant increases in viscosity and ring and ball softening point. Composition and properties of the blends are listed in the Table.
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Civil Engineering (AREA)
- Materials Engineering (AREA)
- Structural Engineering (AREA)
- Health & Medical Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Medicinal Chemistry (AREA)
- Polymers & Plastics (AREA)
- Organic Chemistry (AREA)
- Compositions Of Macromolecular Compounds (AREA)
Abstract
The present invention is an improvement in a process for producing a blend of bitumen and a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene comprising mixing from 88 to 99.5 weight percent of bitumen with 0.5 to 12 weight percent copolymer at 135° to 250° C., agitating the mixture for at least 30 minutes, adding 0.01 to 2 weight percent sulfur and maintaining the mixture under agitation for at least 30 minutes. The improvement comprises utilizing high shear mixing at a shear rate of at least 10,000 second-1 to provide said agitation.
Description
The present invention relates to a process for blending block copolymers of vinyl aromatic hydrocarbons and conjugated dienes with bitumen and crosslinking them with sulfur. More particularly, the present invention relates to such a process which utilizes high shear mixing.
Asphalt is a common material utilized for the preparation of paving and roofing materials and also for coatings such as pipe coatings and tank liners. While the material is suitable in many respects, it inherently is deficient in some physical properties which it would be highly desirable to improve. Efforts have been made in this direction by addition of certain conjugated diene rubbers, ethylene containing plastics like EVA and polyethylene, neoprene, resins, fillers and other materials for the modification of one or more of the physical properties of the asphalt. Each of these added materials modifies the asphalt in one respect or another but certain deficiencies can be noted in all modifiers proposed. For example, some of them have excellent weather resistance, sealing and bonding properties but are often deficient with respect to warm tack, modulus, hardness and other physical properties; and some of them improve only the high temperature performance of asphalt, some only improve the low temperature performance of asphalt, while some lack thermal stability or mixing stability with asphalt.
Since the late 1960s, diene polymer rubbers such as styrenebutadiene rubber and styrene-rubber block copolymers such as styrene-butadiene-styrene and styrene-isoprene-styrene block copolymers have been used to dramatically improve the thermal and mechanical properties of asphalts. Practical application of the rubber addition approach requires that the blended product retain improved properties and homogeneity during transportation, storage and processing. Long term performance of elastomer-modified asphalts also depends on the ability of the blend to maintain thermal and chemical stability.
Such bitumen/block copolymer mixtures have been crosslinked with a crosslinking agent such as sulfur to provide improved mechanical properties. A number of methods for incorporating the sulfur have been used. One of these involves mixing the bitumen and the copolymer together and agitating them for a period of time before adding the sulfur. After the sulfur is added, the agitation is continued for a period of time. This method is advantageous but has the disadvantage that the resulting morphology is relatively coarse. A very fine dispersion of the polymer would provide better high temperature properties. Therefore, it would be advantageous to provide a process for producing such bitumen/block copolymer blends which have a stable and very fine morphology. The present invention provides such a process.
The present invention is an improvement in a process for producing a blend of bitumen and a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene which comprises mixing from 88 to 99.5 weight percent of bitumen with 0.5 to 12 weight percent of copolymer at 135° to 250° C., agitating the mixture for at least 30 minutes, adding 0.01 to 2 percent sulfur to the mixture and maintaining the mixture under agitation for at least 30 minutes. The improvement comprises utilizing high shear mixing at a shear rate of at least 10,000 second-1 to provide the agitation.
The bituminous component in the bituminous-polymer compositions according to the present invention may be a naturally occurring bitumen or derived from a mineral oil. Also, petroleum derivatives obtained by a cracking process, pitch and coal tar can be used as the bituminous component as well as blends of various bituminous materials. Examples of suitable components include distillation or "straight-run bitumens", precipitation bitumens, e.g. propane bitumens, blown bitumens and mixtures thereof. Other suitable bituminous components include mixtures of one or more of these bitumens with extenders such as petroleum extracts, e.g. aromatic extracts, distillates or residues, or with oils.
The block copolymers may be produced by any well known block polymerization or copolymerization procedures including the well-known sequential addition of monomer techniques, incremental addition of monomer technique or coupling technique. As is well known in the block copolymer art, tapered copolymer blocks can be incorporated in the multiblock copolymer by copolymerizing a mixture of conjugated diene and vinyl aromatic hydrocarbon monomers utilizing the difference in their copolymerization reactivity rates. The manufacture of such polymers is described in U.S. Patent Nos. 3,113,986, 4,226,952, and Reissue 27,145, the disclosures of which are herein incorporated by reference. The polymers used herein may be linear polymers, radial polymers having three or more arms, and they may also be star polymers having a plurality of arms. The arms referred to are block copolymers of vinyl aromatic hydrocarbons and conjugated dienes.
Conjugated dienes which may be utilized to prepare the polymers and copolymers include those having from 4 to 8 carbon atoms and also include 1,3-butadiene, 2-methyl-l,3-butadiene(isoprene), 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene and the like. Mixtures of such conjugated dienes may also be used. The preferred conjugated dienes are 1,3-butadiene and isoprene.
Vinyl aromatic hydrocarbons which may be utilized to prepare copolymers include styrene, o-methylstyrene, p-methylstyrene, p-tertbutylstyrene, 2,4-dimethylstyrene, alpha-methylstyrene, vinylnapthalene, vinylanthracene and the like. The preferred vinyl aromatic hydrocarbon is styrene.
The present invention works with both unhydrogenated and hydrogenated polymers. Hydrogenated ones are useful in certain circumstances. While unhydrogenated diene polymers have a number of outstanding technical advantages, one of their principal limitations lies in their sensitivity to oxidation. This can be minimized by hydrogenating the copolymers, especially in the diene blocks. The hydrogenation of these polymers and copolymers may be carried out by a variety of well established processes including hydrogenation in the presence of such catalysts as Raney Nickel, noble metals such as platinum, palladium and the like and soluble transition metal catalysts. Titanium biscyclopentadienyl catalysts may also be used. Suitable hydrogenation processes which can be used are ones wherein the diene-containing polymer or copolymer is dissolved in an inert hydrocarbon diluent such as cyclohexane and hydrogenated by reaction with hydrogen in the presence of a soluble hydrogenation catalyst. Such processes are disclosed in U.S. Pat. Nos. 3,113,986, 4,226,952 and Reissue 27,145, the disclosures of which are herein incorporated by reference. The polymers are hydrogenated in such a manner as to produce hydrogenated polymers having a residual unsaturation content in the polydiene block of less than about 20%, and preferably as close to zero percent as possible, of their original unsaturation content prior to hydrogenation.
The bitumen/block copolymer compositions of the present invention generally comprise from 88 to 99.5, preferably 92 to 99, weight percent asphalt and 0.5 to 12, preferably 1 to 8, weight percent block copolymer. Higher polymer concentrations provide good properties but are not cost effective. Lower polymer concentrations do not provide a continuous polymer network necessary for improved properties. These two materials are mixed together and then subjected to high shear mixing at 135° to 250° C. at a shear rate of at least 10,000 second-1 for a period of at least 30 minutes in order to achieve a blend morphology characterized by a very fine, stable polymer distribution.
After the desired morphology is achieved, sulfur is added in an amount of 0.01 to 2 weight percent and the mixture is maintained under said high shear agitation for at least 30 minutes to achieve complete reaction of the sulfur. The irreversible crosslinking reaction stabilizes the dispersion achieved by the high shear mixing. The high shear rate specified above for the agitation of the bitumen/polymer blend is necessary to achieve the desired morphology and to assure a stable irreversible fine polymer distribution.
Shear rate is defined as the ratio of the speed of the moving part of the mixer or rotor to the gap between the moving part and stationary part or stator of the mixer. For example, a 3 foot diameter impeller rotating at 100 rpm with a clearance of 1/2 inch would provide a shear rate of about 400 second-1. A Silverson L4R mixer with a diameter of 30 millimeters and a gap of approximately 0.1 millimeter rotating at 3000 rpm would provide a shear rate of about 50,000 second-1. Shear rates suitable to this invention may be achieved on a laboratory scale with mixers manufactured by, for example, Silverson or Ross, and on a commercial scale with mixers manufactured by, for example, Siefer or Dalworth. A shear rate of at least 10,000 second-1 is required to achieve the desired morphology of the invention.
Polymer and asphalt as specified below were mixed at 160° C. for 1 1/2 hours using high or low shear mixing. For high shear mixing a Silverson L4R mixer operating at 4000 rpm (greater than 750,000 second-1) was used. For low shear mixing an impeller low shear mixer operating at 1000 rpm (about 000 second-1) was used. After complete mixing of the polymer, sulfur was added and mixed an additional hour. High shear mixing leads to significant increases in viscosity and ring and ball softening point. Composition and properties of the blends are listed in the Table.
______________________________________
A B C D
______________________________________
Asphalt - AC5 phr.sup.3
100 100 100 100
Polymer
1205.sup.1 phr 3 3
KRATON ® D1101.sup.2 phr 3 3
Sulfur phr 0.13 0.13 0.13 0.13
Shear rate High Low High Low
Penetration,
decimillimeters
25° C. 99 99 92 92
4° C. 41 41 38 38
Viscosity
60° C., poise
2400 1900 24000 3000
135° C., centistokes
600 460 670 570
Ring & Ball 127 119 137 124
Softening Point, F
______________________________________
.sup.1 a styrenebutadiene (SB) diblock copolymer
.sup.2 a linear SBS block copolymer
.sup.3 phr parts by weight per 100 parts of rubber (the block copolymer)
Claims (4)
1. In a process for producing a blend of bitumen and a block copolymer of a vinyl aromatic hydrocarbon and a conjugated diene comprising mixing from 88 to 99.5 weight percent of bitumen with 0.5 to 12 weight percent copolymer at 135° to 250° C., agitating the mixture for at least 30 minutes, adding 0.01 to 2 weight percent sulfur and maintaining the mixture under agitation for at least 30 minutes, the improvement which comprises utilizing high shear mixing at a shear rate of at least 10,000 second-1 to provide said agitation.
2. The product of the process of claim 1.
3. The process of claim 1 wherein the bitumen concentration is 92 to 99 weight percent and the polymer concentration is 1 to 8 weight percent.
4. The product of the process of claim 3.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/160,005 USH1484H (en) | 1993-11-30 | 1993-11-30 | Method for obtaining polymer/bitumen blends with improved stability and polymer efficiency |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US08/160,005 USH1484H (en) | 1993-11-30 | 1993-11-30 | Method for obtaining polymer/bitumen blends with improved stability and polymer efficiency |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| USH1484H true USH1484H (en) | 1995-09-05 |
Family
ID=22575072
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| US08/160,005 Abandoned USH1484H (en) | 1993-11-30 | 1993-11-30 | Method for obtaining polymer/bitumen blends with improved stability and polymer efficiency |
Country Status (1)
| Country | Link |
|---|---|
| US (1) | USH1484H (en) |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5710196A (en) * | 1996-08-27 | 1998-01-20 | General Electric Company | Asphalt compositions containing acrylonitrile-butadiene-styrene copolymer |
| WO2000044975A1 (en) * | 1999-01-27 | 2000-08-03 | Polyphalt Inc. | Modified bituminous composition for roof membranes |
| US6362257B1 (en) * | 1999-08-27 | 2002-03-26 | Crafco, Incorporated | Pavement patch material |
| US6569351B1 (en) | 2000-03-14 | 2003-05-27 | Ergon, Inc. | Accelerator-gel additive for use in the production of polymer-modified asphalt |
| US6573315B1 (en) * | 2000-03-30 | 2003-06-03 | The Goodyear Tire & Rubber Company | Modification of asphalt cement |
| US20050137295A1 (en) * | 2003-12-17 | 2005-06-23 | Kraton Polymers U.S. Llc | Bituminous compositions modified by non-blocking elastomers |
| US20060089429A1 (en) * | 2004-10-22 | 2006-04-27 | Fina Technology, Inc. | Use of inorganic acids with crosslinking agents in polymer modified asphalts |
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| DE3710405A1 (en) * | 1986-04-07 | 1987-10-08 | Petrolchemisches Kombinat | Filled bituminous, elastomer-modified, cold-setting mixt. for sealing - contain bitumen emulsion with clay emulsifier, cold- and hot-vulcanising accelerators, sulphur, styrene-butadiene latex and stabiliser |
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| DE3830679A1 (en) * | 1988-03-18 | 1989-09-28 | Petrolchemisches Kombinat | Self-crosslinking emulsion mixture, and process for the preparation thereof |
| WO1989012079A2 (en) * | 1988-06-10 | 1989-12-14 | Fina Research S.A. | Process for preparing bitumen-rubber compositions |
| EP0360656A1 (en) * | 1988-09-09 | 1990-03-28 | Elf Antar France | Method of making a bitumen-polymer composition |
| EP0384254A2 (en) * | 1989-02-21 | 1990-08-29 | BASF Aktiengesellschaft | Latex compounds for asphalt modifications |
| US5120777A (en) * | 1989-06-30 | 1992-06-09 | Elf France | Bitumen/polymer composition exhibiting an adhesiveness which is retained on storage at elevated temperature and process for preparing such a composition |
| EP0467790A1 (en) * | 1990-07-20 | 1992-01-22 | Elf Antar France | Method for preparing in aqueous emulsion a bitumen/polymer binder with a continuous three-dimensional polymeric structure and use of this binder for making coatings or mixtures for road surfacing |
| US5019610A (en) * | 1990-10-18 | 1991-05-28 | Sherex Chemical Company, Inc. | Process for the production of polymer-modified asphalts and asphalts emulsions |
| US5118733A (en) * | 1991-06-06 | 1992-06-02 | Shell Oil Company | Asphalt-block copolymer paving composition |
Cited By (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5710196A (en) * | 1996-08-27 | 1998-01-20 | General Electric Company | Asphalt compositions containing acrylonitrile-butadiene-styrene copolymer |
| US6579921B1 (en) | 1999-01-27 | 2003-06-17 | Polyphalt Inc. | Modified bituminous composition for roof membranes |
| WO2000044975A1 (en) * | 1999-01-27 | 2000-08-03 | Polyphalt Inc. | Modified bituminous composition for roof membranes |
| US6362257B1 (en) * | 1999-08-27 | 2002-03-26 | Crafco, Incorporated | Pavement patch material |
| US6569351B1 (en) | 2000-03-14 | 2003-05-27 | Ergon, Inc. | Accelerator-gel additive for use in the production of polymer-modified asphalt |
| US6569925B2 (en) | 2000-03-14 | 2003-05-27 | Ergon, Incorporated | Accelerator-gel additive for use in the production of polymer modified asphalt |
| US6573315B1 (en) * | 2000-03-30 | 2003-06-03 | The Goodyear Tire & Rubber Company | Modification of asphalt cement |
| US20030187105A1 (en) * | 2000-03-30 | 2003-10-02 | The Goodyear Tire & Rubber Company | Modification of asphalt cement |
| US20030203997A1 (en) * | 2000-03-30 | 2003-10-30 | The Goodyear Tire & Rubber Company | Modification of asphalt cement |
| US6737452B2 (en) * | 2000-03-30 | 2004-05-18 | The Goodyear Tire & Rubber Company | Modification of asphalt cement |
| US6743839B2 (en) * | 2000-03-30 | 2004-06-01 | The Goodyear Tire & Rubber Company | Modification of asphalt cement |
| US20050137295A1 (en) * | 2003-12-17 | 2005-06-23 | Kraton Polymers U.S. Llc | Bituminous compositions modified by non-blocking elastomers |
| US20060089429A1 (en) * | 2004-10-22 | 2006-04-27 | Fina Technology, Inc. | Use of inorganic acids with crosslinking agents in polymer modified asphalts |
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