AU637490B2

AU637490B2 - Improved bitumen composition

Info

Publication number: AU637490B2
Application number: AU76017/91A
Authority: AU
Inventors: Glynn Holleran
Original assignee: Emoleum Australia Ltd
Current assignee: Emoleum Australia Ltd
Priority date: 1990-05-04
Filing date: 1991-04-29
Publication date: 1993-05-27
Anticipated expiration: 2011-04-29
Also published as: AU7601791A

Description

AUSTRALIA

637490 Patent Act COMPLETE SPECIFICATION

(ORIGINAL)

Class Int. Class Application Number: Lodged: Complete Specification Lodged: Accepted: Published: Priority: Related Art: Names(s) of Applicant(s): EMOLEUM (AUSTRALIA) LTD.

Address of Applicants: 3 Bowen (AUSTRALIA) LTD.

MELBOURNE Victoria 3004 Our Address for service is: PHILLIPS ORMONDE FITZPATRICK Patent and Trade Mark Attorneys 367 Collins Street MELBOURNE, Australia 3000 Complete Specification for the invention entitled: IMPROVED BITUMEN COMPOSITION The following statement is full description of this invention, including the best method of performing it known to applicant(s): 1 0804N

-M

-la- IMPROVED BITUMEN COMPOSITION j The present invention relates to an improved bitumen composition. More particularly, the present invention relates to improving the compatibility. of, c tn-11-in -Lye-s- into a bitumen composition.

Bitumen is a naturally occuring hydrocarbon substance or a mixture of various hydrocarbon substances extracted from crude oil. The extraction of bitumen is conducted by a number of different processes such as, vacuum distillation and propane precipitation. The resulting product is usually a blend with other bitumen products of differing physical properties to create a standard bitumen. Alternatively, the bitumen may be blown with air at elevated temperatures to increase hardness and viscosity.

Bitumen may be described as a colloidal dispersion of high molecular weight aromatic hydrocarbons called asphaltenes, dispersed in a continuous phase of lower molecular weight oily resinous material known as maltenes.

The asphaltenes are insoluble in the oily maltene constituents. The asphaltenes generally exist in bitumens as fine to coarse dispersions due to their peptization by the more aromatic resin constituents. That is, the surface chemistry is altered by the absorption of the resins onto the asphaltenes surface which allows for the stability of the dispersion.

As crude oils are variable in chemical composition, their thermodynamic and physical properties are often quite markedly varied as a result of variations in the balance between the various components.

Bitumen often has short comings in properties due to the chemical an' physical structure and general nature of the material. Bitumen is a semi solid and as such is subject to flow under appropriate loading and temperature conditions.

Photoxidative processes also effect the bitumen and often causes embrittlement of the bitumen over a period of time.

Bitumen is also non-newtonian at temperatures below 60 0 C approximately. However, the viscosity does have rough 6460N/WN -2proportion to shear rate. For example, a bitumen that may be softer at low temperatures will tend to be unacceptedly low in viscosity at elevated service temperatures. Conversely, a bitumen with high viscosity at elevated service temperatures would tend to be brittle at lower service temperatures.

Polymers may be added to the bitumen comp, sition to increase viscosity at higher temperatures without correspondingly causing embrittlement at lower temperatures.

Indeed low temperature flexibility and resistance to cracking may be enhanced. Such polymers include functionalized polyolefins, for example high molecular weight polymers such as ethylene-vinylacetate copolymer (EVA) and ethylene methyl acrylate copolymers (EMA), or styrene butadiene copolymers (SBS) and blends of SBS and ethylene vinyl acetate. Such polymers are usually formed in free radical or solution polymerization processes. These polymers are available from major polymer manufacturers such as ICI, Exxon or Dupont.

These types of polymers improve the load bearing capability of the bitumen by improving elastic stiffness and resistance to creep. That is, the bitumen is far more resilient under normal operating conditions. The addition of the polymers also improves the resistance to flexural cracking. In particular applications, for example of the sealing of roads where both emulsion and hot binder polymers are used, the polymers improve cohesion and stone retention within the bitumen. Resistance to oxidation and ultraviolet light are also improved.

The higher the molecular weight of the added polymer, a-i greater the improvement in the mechanical properties of the bitumen are imprqvad.. However, the compatibility, ie. the ability for the polymer to disperse and effectively modify the bitumen is generally worse.

Compatibility is a complex physio-chemical process that involves thermo-dynamic interaction between the bitumen and the polymer. A two phase bitumen/high molecular weight polymer system is inherently unstable on thermo-dynamic grounds as there is no driving force to mix (entropy is not ,,6460N/WN A t.

3 increased). As the molecular weight of the given polymer type increases the mixing becomes even less favourable. The formalion of a network structure involves swelling of the polymer by the maltene fraction and interaction with the resins and asphaltenes. This feature in itself is well documented for styrene butadiene type polymers. In other polymers, it has been suggested that the same effect occurs for any compatible polymer-bitumen system. The effect of reducing asphaltenes and increasing the aromatic content of the maltenes phase has also been demonstrated to dramatically improve the compatibility of some polymer types.

This is consistent with the fact that as little as 6% of a styrene butadiene type polymer can for a continuous matrix in bitumen occupy 40% of the volume or more. Similar effcts have been observed with other polymers. It has been suggested that Hildebrands solubility perameters are a good indicator of the compatibility likely to be achieved but this presupposes adequate characterisation of the base bitumen.

Put more simply, it is most desirable that the polymer swell in the maltenes fraction and associate with the asphaltenes to effectively modify the bulk properties of the bitumen, particularly for functionalised polyolefins. It is however more difficult to achieve this swelling as the molecular weight of the polymer increases or the chemistry of the polymer 23 or bitumen changes significantly.

It would be desirable if a bitumen composition could be modified so as to create an increase in compatibility between the polymer and the bitumen for varying types of bitumen and polymers. The present invention aims to alleviate or at least overcome one or more of the difficulties associated with these techniques.

The present invention resides in a method to improve the compatibility between a variety of bitumen and polymer compositions within the limits of thermodynamics and chemical structure by blending of deasphalted oil or automotive diesel oil with propane deasph-alted tar.

Specifically, according to one embodiment, the present invention resides in a method of modifying a bitumen composition 3'7- by providing;

WDN

.j 4 a bitumen composition containing a polymer additive; and a refined hydrocarbon oil; and blending the refined hydrocarbon oil with the bitumen composition in sufficient quantity to improve the compatibility of the polymer additive with the bitumen composition, with the proviso that when the bitumen composition is bitumen, and the polymer additive is a styrene butadiene polymer or copolymer, the refined hydrocarbon oil is not an aromatic oil.

Typical polymers that are commonly used as additives to bitumen compositions include ethylene or methylene polyolefins and may be copolymerised with one or more of a sulphate, vinyl acetate, methyl acrylate, methyl methacrylate, butylacrylate, sulphonates, nitrates, phosphates, esters, polyesters or styrene butadiene copolymers. Basically, the polymer may be any such polymer that can be functionalized and provide a polar group.

According to a preferred specific embodiment, the invention resides in a method of modifying a bitumen composition by providing a bitumen composition containing a functionalised polyolefin additive; and an aromatic oil; and blending the aromatic oil in sufficient quantity to improve the compatibility of the polyolefin additive with the bitumen composition.

Still further, in another embodiment according to the invention there resides, a method of modifying a bitumen composition by providing; re csH a propane deaa-s-aed-tar- containing a styrene butadiene additive; and an aromatic oil; and blending the aromatic oil in sufficient quantity to improve the compatibility of the styrene butadiene additive with the bitumen composition.

The invention further resides in a base binder material that includes a bitumen composition including a polymer additive, that may have been reblended with a refined hydrocarbon oil rma-olc il according to the methods of the invention.

39 In order to carry out the techniques involved with the WDN1 4a invention, the compatibility between the bitumen and polymer may be measured by performing a mixing test of the polymer chosen and the bitumen. This is done at various combinations of temperature, mixing time and shear.

The temperature is usually varied from 160 to 2300C.

Shear rate is varied from simple spindle/propeller mixing in a 1 litre can to homogenising using a high shear blender.

Compatibility is tested by the measurement of key indicator properties. End point for mixing is fixed as a minimum for the production of an even mix with no lumps.

Mixing is also checked by using X-Ray or ultra violet fluoresence of visible light under microscope. Incident X-Rays or U.V. rays cause the polymer to fluoresce with visible light. A compatible polymer forms an even dispersion. At the point where desirable or complete compatibility is reached (a function of polymer concentration, polymer type and bitumen composition) the continuous matrix is swelled polymer. There is al3o a mixed phase where neither phase dominates. This may be an optimum under some circumstances.

If the polymer is not compatible with the bitumen composition, compatibility may be achieved by the addition of oth raromatic or, hydrocarbon oils. These oils may be refined from lubrication oil refineries or such chemical equipments.

Bitumen may be manufactured in several ways. Crude oil may be vacuum distilled to remove the lower hydrocarbons (fuels, oils). The remaining higher molecula:: weight material is referred to as Vacuum Tower Bottoms, this is then blown 39

WDN

with air at high temperatures to specification, this is a finished bitumen ;nd the composition is fixed. Alternatively the crude oil may be fractionated in a lubrication oil refinery. The heaviest fraction may then be separated into two components by extraction with a light hydrocarbon such as propane, butane or pentane. The oil that is soluble in this is called deasphalted oil (DAO) and the residual is called deasphalted tar (PDT) or propane (butane, pentane etc) precipitated asphalt (PPA). This oil may be recombined with the PDT or PPA to create reconstituted bitumen and is a particular aC\F> rnlon oFTc ^o'lesn or>oss>in efntion.

example of an oil within the scope of the present invention.

It has not previously been realised that with correct modification of the reconstitution of bitumen the compatibility between the polymer and bitumen may be increased. Oils may be added at levels of 0.1 to 20% by weight depending on the bitumen/polymer compatibility requirements. In order to ensure compliance the binder that is produced is tested according to standard binder tests.

A preferred embodiment is a composition that includes 1 to 15% by weight of a functionalised polyolefin additi/e or styrene butadiene polymer additive, 0 to 20% dea-s-ph-a-l-ede oil with the remainder being propane deasphalted tar.

Alternatives to the hydrocarbon oils are, aromatic synthetic oils of suitable molecular weight. To ensure compatibility without taking the bitumen or binder out of the desired specification limits, aromatic oil levels are preferably in excess of 20% by weight. Other oils such as common asphalt rejuvenating agents such as hydrocarbon oils or rubber processing oils may also be used in the context of the present invention.

Suitable base stocks for modification include, but are not limited to, refined bitumens of asphaltene levels less than or equal to 12% by weight in completed bitumen composition by weight.

Once a specification has been produced blending can be done to this specification and compatibility of new bitumens blended or as received from the refinery can be checked.

The following examples are illustrative of the invention and 39 the scope of the invention is not intended to be limited thereto.

WDN 5 WD -6- Example 1 Ethylene Methacrylate Polymers.

Exxon Product XCS 503.

Softening Point: 126 0

C.

Melt Flow Index: 1.1 g/10 min.

Added at 5% by weight to the bitumen base.

A propane Precipitated Asphalt bitumen base of 350-470 Pa.s.

is blended with 0.1-10% Deasphalted oil or Aromatic oils mobilsol 30 or mo.bilsol 40 at the same percentages. The binder is heated, with stirring to 195°C. A propeller mixer capable of mixing the material at 100 rpm is used.

The polymer is added slowly with mixing. The material is mixed until the polymer is fully dispersed. This can be checked by turning off the mixer and ensuring that no separation occurs. Also the toothpaste tube test may be usrd where the binder is poured into a toothpaste tube, sealed and then kept in an oven at 150 0 C for 15 hours. The tube is stripped away and inconsistencies observed. The tube may also be sectioned and the density of the sections compared to theoretical.

The binder should be unifo'rm, density should not vary more 3 than 0.005 g/cm 3 A thin film of the material may also be subjected to U.V. fluorescence (LCPC binder test). The binder should be in the mixed phase or polymer matrix phase. Successful mixes are then characterized.

Note that 36 minutes mixing equals 24 hours mixing on a low shear factory mixer. A maximum of 20 minutes is usually chosen.

G460N/WN l1 C- -7- As the blending of deasphalted oil reduces the viscosity of the'binder, 10% is a preferred maximum.

The chosen blend may be is made in a factory mixer. For blending in a low shear 14-16 hours is' required. The blending is done until the required physical properties are reached.

For blending in high shear 4-5 hours is required.

3% DAO in PD. Tar viscosity 460 Pa.s.

Mixing time in laboratory 45 minutes.

Mixing time in factory 16 hours.. (poor mixing) Modified binder properties: Penetration (25/100/5) 0.1 mm=34 Viscosity 60 0 C. =717 Pa.s.

135 0 C. =1.01 Pa.s.

Density. =1.025g/cm 3 Tortional Recovery. 30s: (Mobil procedure). 30 min: Ring and ball softening pt. 65 0

C

Example 2. Hydrogenated Styrene Butadiene Copolymer.

BASF Product Kuroplast DS6033 Average molecular weight: 100,000.

Melt Flow Index: 3.5 g/10 min.

Added at 5% by weight to the bitumen base.

A Propane Precipitated Asphalt bitumen base of 350-470 Pa.s.

is blended with 0.1-10% Deasphalted oil or Aromatic oils mobilsol 30 or mobilsol 40 at the same percentages. The binder is heated, with stirring to 195 0

C.

6460N/WN

L~

-8- A propeller mixer capable of mixing the material at 100 rpm is used.

The polymer is added slowly with mixing. The material is mixed until the polymer is fully dispersed. This can be checked by' turning off the mixer and ensuring that no separation occurs. Also the toothpaste tube test may be used where the binder is poured into a toothpaste tube, sealed and then kept in an oven at 150 0 C for 15 hours. The tube is stripped away and inconsistencies observed. The tube may also be sectioned and the density of the sections compared to theoretical.

The binder should be uniform, density should not vary more than 0.005 g/cm 3 A thin film of the material may also be subjectd to U.V. fluorescence (LCPC binder test). The binder should be in the mixed phase or polymer matrix phase.

Successful.mixes are then characterised.

As the blending of Deasphalted oil reduces the viscosity of the binder 10% is the usual maximum.

The chosen blend may be made in a factory mixer. For blending in low shear 14-16 hours is required. The blending is done until the required physical properties are reached.

6460N/WN For blending in high shear 4-5 hours is required.

The results are as follows: 3% DAO in PD. Tar viscosity 460 Pa.s.

Mixing time in laboratory 35 minutes.

Mixing time in factory 14.hours. (poor mixing) Modified binder properties: Penetration (25/100/5) 0.1mm=43 Density: 0.996g/cm 3 Tortional Recovery. 30s: (Mobil procedure)-. 30 min: 36% Ring and Ball Softening Pt.:61 0

C.

Example 3 Styrene butadiene copolymers for sealing.

Deasphalted tar from arab light crude was used and deasphalted oil from arab light crude added at 2-16% depending on the deasphalted tar penetration and was adjusted to penetration of 100 (tenths of mm at 25 0 C according to United States standard styrene butadiene copolymer, TR 1184 (Shell Chemicals) or equivalent were mixed under high or low shear to uniform properties at 180-200 0

C.

The following properties were obtained.

RT

Torsional recovery (Mobil/TRA NSW Method) 30 sec 36% 30 min 76% Ring and Ball Softening Point: 76 0

C

Viscosity at 135°C: 0.940 Pa.s Penetration at 25 0 C: 60 (tenths of mm) Example 4 Styrene butadiene and ethylene vinyl acetate copolymer blends for sealing.

Deasphalted tar from arab light crude was used and deasphalted oil from arab light crude added at 2-16% depending on the deasphalted tar penetration and adjusted to penetration of 100 (tenths of mm 25 0 C for United States standard styrene butadiene TR 1101 (Shell Chemicals) or equivalent and 1% ethylene vinyl acetate grade polybilt 101 (Exxon Chemicals) or equivalent were mixed under high or low shear to uniform properties at 180-200 0

C.

The following properties were obtained: lTfA Torsional recovery (Mobil/ TRA NSW Method) 30 sec 31% min 77% Ring and Ball Softening Point 66°C Viscosity at 135 0 C: 1.130 Pa.s.

Penetration at 25 0 C 48 (tenths of mm) Example Ethylene methylacrylate copolymers Deasphalted tar from arab light crude was used and deasphalted oil from arab light crude added at 2-16% depending on the deasphalted tar penetration adjusted to penetration of (tenths of mm at 25°C United States standard Polybilt XCS 503 (Exxon Chemicals) was added and mixed under high or low shear to uniform properties at 180-200 0

C.

The following properties wert obtained: Torsional recovery 30 sec 24% Mobil/ '-RAf SW Method 30 min 54% Ring and Ball Softening Point Viscosity at 135 C 1.110 Pa.s Penetration at 25 0 C 61 (tenths of mm) 6460N/WDN t j -11- Note the final viscosity in properties are adjusted depending upon the application. Low penetration (15-74 hot mixed asphalt) 80-200 for sealing bitumen or emulsion.

It should be understood that the embodiments described herein are merely preferable and that alterations and amendments that do not depart from the spirit of the invention are included with the scope.

6460N/WN

Claims

1. A method of modifying a bitumen composition by providing; a bitumen composition containing a polymer additive; and a refined hydrocarbon oil; and blending the refined hydrocarbon oil with the bitumen composition in sufficient quantity to improve the compatibility of the polymer additive with the bitumen composition, with the proviso that when the bitumen composition is bitumen, and the polymer additive is a styrene butadiene polymer or copolymer, the refined hydrocarbon oil is not an aromatic oil.

2. A method according to claim 1 wherein the hydrocarbon oil is a deasphalted oil or automotive diesel oil; and rec; -s ks\ the bitumen composition is a propane &e-ph-a--ted-- a-r.

3. A method according to claim 1 or 2 wherein the polymer additive is selected from an ethylene or methylene polyolefin, optionally copolymerised with one or more of a sulphate, vinyl acetate, methylacrylate, methylmethacrylate, butylacrylate, sulphonate, nitrate, phosphate, ester, polyester; or a styrene butadiene copolymer or a blend of a styrene butadiene copolymer and ethylene vinylacetate.

4. A method according to claim 1, 2 or 3 wherein the hydrocarbon oil is added at levels of between approximately 0.1 to 20% by weight. A method of modifying a bitumen composition by providing a bitumen composition containing a functionalised polyolefin additive; and an aromatic oil; and blending the aromatic oil in sufficient quantity to improve the compatibility of the polyolefin additive with the bitumen composition.

SWDN 12

6. A method according to functionalised polyolefin additive or methylene polyolefin, optionally more of a sulphate, vinyl S methylmethacrylate, cutylacrylate, phosphate, ester or a polyester. claim 5 wherein the is selected from ethylene copolymerised with one or acetate, methylacrylate, sulphonate, nitrate,

7. A method of modifying a bitumen composition by providing; c, c. kckt a propane d-ea-s-pha-l-ted---tar- containing a styrene butadiene additive; and an aromatic oil; and blending the aromatic oil in sufficient quantity to improve the compatibility of the styrene butadiene additive with the bitumen composition.

8. A method according to claim 7, wherein the styrene butadiene additive is a styrene butadiene polymer or copolymer, or blends thereof with vinylacetate.

9. A method according to any one of claims 5 to 8 wherein the aromatic oil is added at levels of between approximately 0.1 to 20% by weight.

10, A method according to claim 5 or 6 wherein the composition comprises 1 to 15% of the functionalised polyolefin additive; A 0 to 20% d-esp.ha-l-t-ed oil; with the remainder being propane easpha--ted--.a-r/.

11. A method according to claim 7 or 8 wherein the composition comprises 1 to 15% of the styrene butadiene additive; 0 to 20% daesphalt44d;oil; with the remainder being propane dea-pha-l-ted-t-a-

12. A method according to any one of the preceding claims wherein the bitumen composition comprises 12% or less of asphaltenes. P "1a 13 -M

13. A base binder material for a bitumen composition comprising; a bitumen composition including a polymer additive; and a refined hydrocarbon oil reblended with the bitumen composition in sufficient quantity to improve the compatibility of the polymer additive with the bitumen composition, with the proviso that when the bitumen composition is bitumen, and the polymer additive is a styrene butadiene polymer or copolymer, the refined hydrocarbon oil is not an aromatic oil.

14. A base binder material according to claim 13 wherein; the hydrocarbon oil is a deasphalted oil or automotive diesel oil; and pc-e pl e sCh- t the bitumen composition is a propane deaph-a-l-ted--ta-r.

A base binder material according to claim 13 wherein the polymer additive is selected from an ethylene or methylene polyolefin, optionally copolymerised with one or more of a sulphate vinyl acetate, methylacrylate, methylmethacrylate, butylacrylate, sulphonate, nitrate, phosphate, ester, polyester; or a styrene butadiene copolymer or a blend of styrene butadiene copolymer and ethylene vinylacete.

16. A base binder material according to claim 13, 14 or wherein the hydrocarbon oil is added at levels of 0.1 to by weight.

17. A base binder material for a bitumen composition comprising; a bitumen composition containing a functionalised polyolefin; and an aromatic oil blended with the bitumen composition in a sufficient quantity to improve the compatibility of the polyolefin with the bitumen composition.

18. A base binder material according to claim 17 wherein the functionalised polyolefin is selected from an ethylene or 39 methylene polyolefin, optionally copolymerised with one or WDN 14 WDN 14 more of a sulphate vinyl acetate, methylacrylate, methylmethacrylate, butylacrylate, sulphonate, nitrate, phosphate, ester or polyester.

19. A base binder material for a bitumen composition comprising: a propane deasphalted tar containing a styrene butadiene additive and; an aromatic oil blended with the propane deasphalted tar in a sufficient quantity to improve the compatibility of the styrene butadiene additive and the bitumen composition.

A base binder material according to claim 19 wherein the styrene butadiene additive is a styrene butadiene polymer or copolymer or blends thereof with ethylene vinylacete.

21. A base binder material according to any one of claims 17 to 20 wherein the aromatic oil is added at levels of between approximately 0.1 to 20% by weight.

22. A base binder material according to claims 17 or 18 comprising 1 to 15% by weight of the functionalised polyolefin additive; and 0 to 20% by weight 4easphal-ted oil; i with the remainder being propane deash-a-l-ed--t-a-r

23. A base binder material according to claim 19 or comprising 1 to 15% by weight of styrene butadiene additive; 0 to 20% by weight deasphealt4 oil; c o cN with the remainder being propane deae-pha-l-ed--t-a-

24. A base binder material according to any one of claims 13 to 23 wherein the bitumen composition comprises 12% or less by weight of asphaltene levels.

A method according to claim 1, 5 or 7, substantially as 39 hereinbefore described with reference to any one of the WDN 15 examples.

26. A base binder according to claim 13, 17 or 19, substantially as hereinbefore described with reference to any one of the examples. DATED: 7 September 1992 PHILLIPS ORMONDE FITZPATRICK Attorneys for: EMOLEUM (AUSTRALIA) LTD. D6s~h"~A: rB 0251N WDN 16