Biopolymer asphalt substitute

Abstract

The invention relates to a biopolymer asphalt substitute. The biopolymer is non-plant-based. A significant amount of the biopolymer can be included in the blend with the asphalt without substantially altering or modifying the (viscoelastic) properties of the blend.

Description

TECHNICAL FIELD

[0001] The present invention relates to a substitute material for bitumen. BACKGROUND

[0002] Bitumen is a material with multiple uses, usually obtained as the heaviest fraction in the oil distillation process, i.e. the residue left over from the distillation of petroleum, hence the name: barrel bottom. Due to the origin of the crude oil and the distillation process, the resulting bitumen can have a wide range of properties and characteristics.

[0003] Due to the cost of crude oil, the bitumen industry is facing a supply problem of bitumen. With the expected decrease in production of fossil fuels, there is an urgent need for alternative bitumen products to exist. In addition, the goal of achieving carbon dioxide neutrality in road transport infrastructure forces the bitumen industry to look for alternative sources of material to replace bitumen products based on crude oil. In the past decades, the focus has been on the use of plant-based oils, such as soybean oil, sunflower oil, rapeseed oil, palm oil, etc. Similarly, in other areas of application of bitumen, such as roofing materials and waterproof membranes, it is desirable to find a substitute for bitumen.

[0004] One suggestion is to use plant-based materials as a substitute for bitumen. However, this approach is not in line with the needs of the human and animal food supply. The supply of bitumen binders competing with the human and animal food supply is undesirable and potentially very dangerous.

[0005] US20170096558A1 describes a bitumen composition comprising a lignin compound or a derivative thereof; the lignin compound is derived from wood.

[0006] It is desirable to provide bitumen substitute compounds from other sources to make the supply stream more flexible and diverse and to benefit more fully from the sources of materials. SUMMARY

[0007] It is an object of the present invention to provide a biopolymer substitute for bitumen, in particular a non-plant-based biopolymer.

[0008] A first aspect of the present invention relates to the use of a biopolymer, i.e. a copolymer comprising 3-hydroxybutyrate monomers and 3-hydroxyvalerate monomers (PHBV), as a substitute for bitumen or bitumen.

[0009] Preferably, the copolymer comprises at least 90 wt% of 3-hydroxybutyrate monomers and 3-hydroxyvalerate monomers in total, relative to the total weight of the copolymer. Preferably, the use is a replacement of bitumen with 10-30 wt% of PHBV, based on the total amount of PHBV and bitumen. The use is for example the use of PHBV as a substitute for bitumen or bitumen in paving or roofing materials.

[0010] Also provided is a composition or material comprising asphalt and a copolymer comprising 3-hydroxybutyrate monomers and 3-hydroxyvalerate monomers (PHBV); preferably as a partial replacement of asphalt; and the use of PHBV as a partial replacement of asphalt in a composition. The composition preferably comprises at least 10 wt% PHBV, based on the total weight of asphalt and PHBV. The composition is for example an asphalt concrete composition, wherein the composition further comprises mineral aggregates. The mineral aggregates preferably include one or more components selected from the group consisting of sand, gravel, crushed stone, slag and recycled concrete. Also provided are roofing or paving materials and membranes comprising the composition. Other uses of the composition are also possible.

[0011] The present invention also relates to a method of preparing a predetermined amount of an asphalt composition, preferably the inventive composition, comprising determining the amount of asphalt composition to be produced based on 100 wt% asphalt, and providing an asphalt fraction in an amount of 90 wt% or less, such as 80 wt% or less, or 75 wt% or less of the determined amount of the asphalt composition, and including at least 10 wt% PHBV, such as at least 15 wt%, or at least 20 wt%, or at least 25 wt%, and / or at most 50 wt% PHBV in the asphalt composition. The PHBV fraction is for example included by blending the mixture with asphalt at a temperature of 140-160 °C and preferably under high shear. Also provided is the use of PHBV as a replacement of asphalt in the prepared asphalt composition.

[0012] The present invention thus relates to a biopolymer asphalt replacement. The biopolymer is non-plant based. A significant amount of biopolymer can be included in a blend with asphalt without substantially changing or modifying the (viscoelastic) properties of the blend. BRIEF DESCRIPTION OF DRAWINGS

[0013] Figure 1 DSR master curves are shown for soft (70 / 100) asphalt compositions comprising 0 and 10 wt% PHBV (Fig.).

[0014] Figure 2 DSR master curves are shown for hard (40 / 60) asphalt compositions comprising 0, 10, 20 and 30 wt% PHBV, respectively (Fig.).

[0015] Figure 3 Microscopic images are shown for 70 / 100 asphalt samples with a) 0% PHBV and b) 10% PHBV.

[0016] Any embodiment shown in the figures is merely an example and does not limit the invention. DETAILED DESCRIPTION

[0017] The present invention is based on the insight that poly-3-hydroxybutyrate-co-3- hydroxyvalerate (PHBV) can be used as a substitute for asphalt. Advantageously, PHBV can be obtained from waste streams from waste water treatment processes and is found to be suitable as an asphalt substitute, in particular as an asphalt binder. The use as an asphalt substitute can be distinguished from the use as an asphalt modifier.

[0018] The use of PHBV as an asphalt substitute facilitates the utilization of water sludge produced in water treatment processes. The use of PHBV in road construction is a disruptive technology that has the potential to change road construction methods that have been used for over a century, i.e. the use of asphalt as a binder derived from crude oil. The use of PHBV as an asphalt binder can improve the environmental, social and financial outcomes of the road construction industry.

[0019] The use of PHBV as an asphalt substitute facilitates a circular economy. Because PHBV is derived from, for example, a waste water treatment process. In one example, PHBV is a product of an industrial waste water treatment process, for example from paper making, wherein a fermentation process is used to cultivate a leachate, i.e. bacteria that contain PHBV. In such a process, the leachate is removed from the water (filtered), the clean water is returned to the factory, illustrating a perfect industrial circular process. The fermentation process cultivates bacteria, but also produces gas (which can be used to replace natural gas). Once fermented, the bacterial sludge with PHBV is processed (i.e. PHBV extraction), and the biomass residue from the processing (PHBV extraction) contains proteins and nutrients that can be used as a soil fertilizer crop nutrient. A second option is to use recycled PHBV. In such an embodiment, PHBV is initially used to produce articles. At the end of their useful life, they are melted, and the resulting PHBV can be used for asphalt production. The present invention also relates to these methods of manufacturing PHBV, which are examples of a circular economy.

[0020] The use of PHBV disclosed herein is also completely different from existing uses of PHBV, for example in specialized packaging, orthopedic devices and drug controlled release.

[0021] Surprisingly, it was found that blends of asphalt and PHBV, in the examples 10, 20 and 30 wt% PHBV, exhibit mechanical performance characteristics (complex shear modulus and phase angle) comparable to pure asphalt, as well as other characteristics comparable to pure asphalt, for example as determined with GPC and FTIR.

[0022] Thus, the present invention provides a biopolymer asphalt substitute, in particular a non-plant based biopolymer for use as an asphalt substitute.

[0023] There are significant differences between the terminology used for bitumen in Europe and the United States. In Europe, the term "bitumen" or "asphaltic bitumen" is used, while in the United States, the same material is referred to as "asphalt," "asphalt cement," or "asphalt binder." To avoid confusion, the European terminology will be used in this application.

[0024] Asphalt typically comprises cycloalkanes, polar aromatics, saturated hydrocarbons, and asphaltenes.

[0025] Cycloalkyl aromatic compounds may include partially hydrogenated polycyclic aromatic compounds. Polar aromatic compounds may include high molecular weight phenols and carboxylic acids. Asphaltenes may include high molecular weight phenols and heterocyclic compounds.

[0026] The asphalt contains, for example, 5 to 25% by weight asphaltenes, which are dispersed in 90 to 65% by weight of n-alkane (pentane or heptane) soluble molecular components.

[0027] As used in this disclosure, PHBV refers to copolymers comprising 3-hydroxybutyrate monomer (HB) and 3-hydroxyvalerate monomer (HV); and optionally other monomers and modifiers. The copolymer comprises, for example, at least 80% by weight or at least 90% by weight of HB and HV monomers in total, relative to the total mass of the copolymer. PHBV is a polyhydroxyalkanoate (PHA).

[0028] The bitumen / PHBV mixture has, for example, a number-average molecular weight of at least 400, or at least 500, or at least 600, and / or at most 1000; and / or a weight-average molecular weight of at least 1000, or at least 1200, or at least 1400, such as at most 2000; all in Daltons.

[0029] The polydispersity index (PDI) is used to measure the breadth of molecular weight distribution and is calculated using the following formula:

[0030]

[0031] A higher polydispersity index (PDI) indicates a wider molecular weight distribution. Monodisperse polymers (such as proteins) with all chain lengths of equal length have a Mw / Mn ratio of 1. The optimal synthetic polymer (the narrow polymer used for calibration) has an Mw / Mn ratio of 1.02 to 1.10. Stepwise polymerization typically produces an Mw / Mn value of approximately 2.0, while chain reactions produce Mw / Mn values ​​of 1.5 to 20. The PDI of the PHBV / asphalt blends of this invention is typically higher than 2.0, for example, higher than 2.1, or higher than 2.2, and / or, for example, up to 3.0 or up to 2.5. These PDI values ​​indicate that the blends have a wide molecular distribution (PDI > 2.0). Experimental results show that the molecular distribution of all blends is very similar, with a slight increase in the PDI value of blends containing 30% PHBV; this supports the use of PHBV as an asphalt substitute.

[0032] Molecular weight can be determined, for example, by gel permeation chromatography (GPC).

[0033] PHBV can be obtained, for example, by extraction from organic waste sludge; rather than limiting the invention to any particular method of obtaining PHBV.

[0034] An exemplary method for obtaining PHBV is described in EP2956493.

[0035] The background reference for this extraction is Elhami et al., Extraction of low molecular weight polyhydroxyalkanoates from mixed microbial cultures using bio-based solvents, Separation and Purification Technology, Volume 299, 2022, 121773, DOI:10.1016 / j.seppur.2022.121773. Another reference describing a method for obtaining PHBV is Weker et al., Consistent production of high quality PHA using activated sludge harvested from full scale municipal wastewater treatment – ​​PHARIO. Water Sci Technol 28 December 2018; 78 (11): 2256–2269. doi: 10.2166 / wst.2018.502.

[0036] PHBV is a non-plant-based biopolymer. PHBV is obtained from microbial sources, particularly from bacteria.

[0037] One embodiment of the present invention relates to the use of PHBV as a substitute for bitumen.

[0038] One embodiment provides a method for reducing the asphalt content of an asphalt composition, the method involving including PHBV in the asphalt composition. A method for manufacturing an asphalt composition is also provided, the method comprising the steps of incorporating a certain amount of PHBV into the asphalt composition and reducing the asphalt portion of the composition by the same weight. Preferably, in this method, PHBV is included in at least 10% by weight of the total amount of the asphalt composition, and preferably, the asphalt portion is reduced by at least 10% by weight.

[0039] A method for preparing a predetermined amount of asphalt composition is also provided, the method comprising determining the amount of asphalt composition to be produced based on 100% by weight of asphalt, providing an asphalt fraction in an amount of 90% by weight or less of the determined amount of the asphalt composition, and containing at least 10% by weight of PHBV, for example up to 50% by weight of PHBV, in the asphalt composition. In this way, PHBV can be used as a substitute or alternative to asphalt and for reducing asphalt consumption.

[0040] The PHBV portion is preferably included by blending the mixture with asphalt at a temperature of 140°C-160°C and preferably at high shear (>200 RPM or above 300 RPM, where RPM = revolutions per minute).

[0041] Compositions comprising PHBV and bitumen are also provided. Preferably, PHBV is a partial substitute for bitumen at least 10% by weight, for example up to 50% by weight. The composition may also contain additives and modifiers.

[0042] The composition is, for example, an asphalt concrete composition. This composition, particularly an asphalt concrete composition, preferably contains mineral aggregate. The mineral aggregate preferably comprises one or more components selected from the group consisting of sand, gravel, crushed stone, slag, and recycled concrete. Based on the total weight of the entire composition, particularly based on the total weight of the asphalt aggregate composition, the composition contains, for example, at least 10% by weight or at least 50% by weight of the said mineral aggregate and, for example, at least 1.0% by weight or at least 10% by weight of an asphalt composition containing PHBV and asphalt. Therefore, a method for preparing mineral aggregate is provided, comprising mixing the composition containing PHBV and asphalt with the mineral aggregate.

[0043] This disclosure also provides membranes, roofing or paving materials each comprising PHBV, particularly membranes, roofing and paving materials comprising asphalt compositions containing PHBV and bitumen, preferably as described above. Paving materials preferably further include the aforementioned mineral aggregates. Based on the total weight of each article, the membrane, roofing material and paving material, for example, each independently comprises at least 1.0% by weight of PHBV.

[0044] Asphalt compositions containing bitumen and BHPV are used, for example but not limited to, membranes such as leak-proof membranes, waterproof membranes, and sound-insulating membranes. The compositions are also suitable for paving and roofing materials. The compositions can be used more broadly in known applications of bitumen.

[0045] Example

[0046] The invention will now be further illustrated by the following non-limiting embodiments. These embodiments do not limit the invention, nor do they limit the claims.

[0047] Example 1

[0048] Method

[0049] PHBV is obtained from organic waste leachate through solvent extraction, that is, from the liquid produced by leaching water through solid waste.

[0050] PHBV is mixed with two types of asphalt: soft asphalt (penetration grade 70 / 100 or 70 / 100 pen) and hard asphalt (penetration grade 40 / 60 or 40 / 60 pen). The penetration grade is as defined in ASTM D5 (2006). Mixing is performed as follows: hard asphalt is manually mixed at 160°C, and soft asphalt is mechanically mixed at 160°C and 225 rpm for 30 minutes. Dynamic shear rheometer (DSR) master curves are obtained.

[0051] Dynamic shear rheometer (DSR) tests were conducted according to EN 14770:2012. The DSR method was used to study the stiffness change of asphalt in 10°C increments over a temperature range between -10°C and 60°C. The first test was conducted using a plate with a diameter of 8 mm over a temperature range between -10°C and 30°C; the second test was conducted using a plate with a diameter of 25 mm over a temperature range between 30°C and 60°C. All tests were conducted at frequencies of 0.1–400 rad / sec (0.02–64 Hz). Complex shear modulus and phase angle were recorded. For each type of asphalt, three asphalt mixtures containing 0%, 10%, and 20% PHBV were prepared and tested. Samples consisting of 100% PHBV were also tested.

[0052] Fourier transform infrared spectroscopy (FTIR) is used to study the distribution of chemical functional groups and potential differences between pure and mixed asphalt samples. FTIR is commonly used to identify asphalt aging behavior and polymer content. Infrared radiation is used because bonds in different functional groups absorb infrared radiation at specific wavelengths to varying degrees. Functional group identification was performed on pure asphalt and mixed samples, as well as pure PHBV samples, using the Perkin Elmer universal ATR sampling attachment. Spectra were recorded in absorbance mode in the wavenumber range of 4000–600 cm⁻¹, with a resolution of 4 cm⁻¹ and 24 scans. The background spectrum of an empty, clean ATR crystal was recorded before each measurement. The binder sample was applied to the ATR crystal within 1 minute after the background spectrum was recorded.

[0053] Gel permeation chromatography (GPC) was performed according to EN ISO 13885-1:2020 guidelines. A column tightly packed with rigid particles containing uniformly sized micropores was used as the stationary phase. The eluent was used as the mobile phase, flowing through the column along with the sample. The separation of different components with different molecular sizes was achieved based on the fact that smaller molecules can penetrate deeper into the pores, are therefore immobilized, and spend more time in the column. Retention time is a measure of molecular size and molecular weight, as these two are closely linked. Various components were separated according to molecular size using three columns (APC XT 45, 1.7 µm, APC XT 200, 2.5 µm, and APC XT 450, 2.5 µm). Tetrahydrofuran (THF) was used as both eluent and solvent to produce a solution of a specific concentration (approximately 1.2 g / L), which was then filtered using a Milex FH syringe microfilter (13 mm diameter, 0.45 µm pore size to remove any insoluble fractions). The experiments were conducted at a constant column temperature of 35°C and a constant flow rate of isocratic solvent at 0.5 ml / min. For component detection, a combination of a photodiode array detector (PDA) and a refractive index detector (RI) in the 190–450 nm range was used. For molecular weight determination, an ultraviolet detector (PDA) at a wavelength of 254 nm was used.

[0054] Differential scanning calorimetry (DSC) was used as the thermal analysis technique according to EN ISO 11357-1:2016. A DSC 600 from Perkin Elmer was used within a temperature range of -75°C to 140°C. The sample was first precisely measured and placed in a small aluminum cup, which was then sealed before being placed in the DSC chamber. The sample was first heated slowly to 80°C, then cooled to -75°C, and finally heated to 180°C under constant heat flux to establish its thermal history.

[0055] Results

[0056] Figure 1 The master DSR curves for soft (70 / 100) bitumen compositions containing 0 and 10 wt% PHBV are shown in the figure. Curve A represents the phase angle results for samples with 0 and 10 wt% PHBV, and curve M represents the complex shear modulus. The sample containing 10% PHBV exhibits essentially the same viscoelasticity as the sample without the PHBV fraction; surprisingly, this suggests that PHBV is suitable as a bitumen substitute without significantly altering the viscoelasticity.

[0057] Figure 2 The master DSR curves for hard (40 / 60) bitumen compositions containing 0, 10, 20, and 30 wt% PHBV are shown in the figure. Curve A represents the phase angle results for samples with 0, 10, 20, and 30% PHBV, and curve M represents the complex shear modulus. Samples containing up to 30 wt% PHBV exhibit essentially the same viscoelasticity as samples without the PHBV fraction; surprisingly, this suggests that PHBV is suitable as a bitumen substitute without significantly altering these properties.

[0058] Figure 3 Microscopic images of 70 / 100 bitumen samples with a) 0% PHBV and b) 10% PHBV are shown, demonstrating good mixing after mechanical mixing at 160°C and 225 rpm for 30 minutes.

[0059] Table 1 shows the GPC (gel permeation chromatography) results for 40 / 60 samples with different amounts of PHBV as bitumen substitutes, and Table 2 shows the GPC results for 70 / 100 samples with different amounts of PHBV substitutes. The units for Mn, Mw, and Mz are Daltons.

[0060] It can be seen that the addition of PHBV basically does not change its molecular weight and molecular weight distribution. However, 40 / 60pen + 0%-30% PHBV shows a gradual increase in average molecular weight (Mz), indicating the concentration of macromolecules in the blend.

[0061] Between pure bitumen and blends containing 10% PHBV, blends of 70 / 100pen+0% or 10% PHBV showed an initial increase in average molecular weight.

[0062] Table 1. Mass distribution of 40 / 60 bitumen containing PHBV

[0063]

[0064] Table 2 Mass distribution of 70 / 100 bitumen containing PHBV

[0065]

[0066] Furthermore, additional FTIR results indicate that all blends have comparable chemical compositions, with the sample having 30% PHBV showing a similar composition at 1680 cm⁻¹. -1 The peak at the point becomes visible, indicating the presence of a ketone group; this peak is also present in pure PHBV samples with higher intensity.

[0067] Additional DSC data for 40 / 60 pen asphalt blends with and without PHBV. The results show that the addition of PHBV to the asphalt blends has little effect on the heat capacity and glass transition temperature (Tg). The Tg values ​​for all three blends are between 20°C and 22°C.

[0068] Additional DSC test data for 70 / 100 pen asphalt blends with and without PHBV indicate that, similar to 40 / 60 pen asphalt blends, PHBV has little effect on the glass transition temperature (Tg) of the blends. The Tg values ​​of the 70 / 100 pen blends range from 22.4℃ to 23.5℃.

Claims

1. Use of copolymers containing 3-hydroxybutyrate monomer and 3-hydroxyvalerate monomer (PHBV) as a substitute for bitumen.

2. The use according to claim 1, wherein the copolymer comprises at least 90% by weight of 3-hydroxybutyrate monomer and 3-hydroxyvalerate monomer relative to the total weight of the copolymer.

3. The use according to claims 1 and 2, for replacing asphalt with 10-30% by weight of PHBV based on PHBV and total asphalt volume.

4. The use according to any one of the preceding claims, for use as a paving or roofing material.

5. A composition comprising bitumen and a copolymer, said copolymer comprising 3-hydroxybutyrate monomer and 3-hydroxyvalerate monomer (PHBV) as partial substitutes for said bitumen.

6. The composition according to claim 5, based on the total weight of bitumen and poly-3-hydroxybutyrate-co-3-hydroxyvalerate (PHBV), comprises at least 10% by weight of poly-3-hydroxybutyrate-co-3-hydroxyvalerate.

7. The composition according to claim 5 or 6, wherein the PHBV copolymer comprises a total of at least 90% by weight of 3-hydroxybutyrate monomer and 3-hydroxyvalerate monomer relative to the total weight of the copolymer.

8. The composition according to any one of claims 5-7, particularly the asphalt concrete composition, the composition further comprising mineral aggregates, wherein the mineral aggregates preferably comprise one or more components selected from the group consisting of sand, gravel, crushed stone, slag and recycled concrete.

9. A roofing material comprising the composition according to any one of claims 5-8.

10. A paving material comprising the composition according to any one of claims 5-8.

11. A method for preparing a predetermined amount of the composition according to any one of claims 5-8, the method comprising: - Determine the amount of the asphalt composition to be produced based on 100% by weight of asphalt, and - Provide 90% by weight or less of the asphalt portion of the defined amount of the asphalt composition, and include at least 10% by weight of a copolymer (PHBV) comprising 3-hydroxybutyrate monomer and 3-hydroxyvalerate monomer, for example up to 50% by weight of PHBV.

12. The method of claim 11, wherein the PHBV portion is included by blending the mixture with bitumen at a temperature of 140°C-160°C and preferably under high shear.

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