Method for improving asphalt by using polyester recovery by-product pyrolytic carbon black

Abstract

The invention provides a method for improving asphalt by using polyester recovery by-product pyrolytic carbon black, and relates to the technical field of asphalt modification. The invention relates to a method for improving asphalt by using polyester recovery by-product pyrolytic carbon black. The polyester recovery by-product pyrolytic carbon black accounting for 2-15% of the weight of matrix asphalt is added into the matrix asphalt; the polyester recovery by-product pyrolytic carbon black is carbon black obtained by carrying out thermal cracking on a polyester recovery by-product. Preferably, the pyrolytic carbon black can also be dispersed by adopting a jet mill, and a dispersing agent is added to reduce agglomeration and improve the compatibility and dispersity of the pyrolytic carbon black in the asphalt. When the pyrolytic carbon black is added into the matrix asphalt, the viscosity, plasticity, temperature stability and other properties of the asphalt can be obviously improved, and reutilization of resources is realized.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of asphalt modification, and relates to a method for improving asphalt by polyester recycling byproduct pyrolysis carbon black. BACKGROUND

[0002] Polyesters, such as PET, have been recycled on a large scale. One method of polyester recycling is chemical method, in which ethylene glycol is added to polyesters for alcoholysis to obtain terephthalic acid diethylene glycol ester BHET and its oligomers. However, the chemical method cannot completely alcoholize polyesters, resulting in byproducts that cannot be recycled. Based on the process steps of the byproducts and the composition of the substances in the byproducts, the byproducts are generally divided into two ester byproducts and alcohol byproducts. With the continuous expansion of polyester recycling scale, if the ester byproducts and alcohol byproducts cannot be further processed, serious environmental problems and resource waste problems will still be caused. SUMMARY

[0003] The method of thermally decomposing polyester recycling byproducts to produce combustible gas and solid carbon black, or mineral oil, is an effective way to realize the recycling of these byproducts. The combustible gas and mineral oil can be directly reused, and the reuse of solid carbon black is also being explored. Based on this, the application provides a method for improving asphalt by polyester recycling byproduct pyrolysis carbon black.

[0004] The technical scheme of the application is as follows:

[0005] A method for improving asphalt by polyester recycling byproduct pyrolysis carbon black, in which 2-15% of polyester recycling byproduct pyrolysis carbon black by weight of the base asphalt is added to the base asphalt.

[0006] The polyester recycling byproduct pyrolysis carbon black is carbon black obtained by thermally cracking the byproducts of polyester recycling.

[0007] Preferably, the byproducts of polyester recycling include ester byproducts and alcohol byproducts.

[0008] Preferably, the temperature of the thermal cracking is 400-500 DEG C, under 1 atmosphere pressure, in an oxygen-free or micro-oxygen environment.

[0009] Preferably, the content of mineral oil in the pyrolysis carbon black is not more than 1 ppm.

[0010] Preferably, the pyrolysis carbon black is pre-ground and dispersed by using an air flow mill.

[0011] More preferably, a combination of stearate and carbon black dispersant is added as a dispersion aid during the air flow mill dispersion.

[0012] Further preferably, the composition exhibits a solid state at no more than 40℃.

[0013] Preferably, the matrix asphalt further comprises 1-5% by weight of the matrix asphalt of nanoscale carbon black.

[0014] More preferably, the weight ratio of the pyrolytic carbon black to the nanoscale carbon black is 1:1-10:1.

[0015] Preferably, the matrix asphalt further comprises one or a combination of two or more of an antioxidant, a toughening agent, an ultraviolet resistant agent, a viscosity adjusting agent, a mineral aggregate, and a tackifier.

[0016] The beneficial effects of the present application are:

[0017] (1) The present application applies pyrolytic carbon black produced by thermal cracking of polyester recycling byproducts to asphalt, and finds that the viscosity, plasticity, and temperature stability of the asphalt are significantly improved.

[0018] (2) The present application grinds and disperses the pyrolytic carbon black using an air flow mill, and adds a dispersing aid, further improving the dispersibility and compatibility of the pyrolytic carbon black in the asphalt, and the effect of the pyrolytic carbon black in the asphalt is more obvious. DETAILED DESCRIPTION

[0019] The technical solutions of the present application are further described and explained below through specific embodiments.

[0020] In order to improve the utilization of pyrolytic carbon black, which is a thermal cracking product of polyester recycling byproducts, the present application provides a method for improving asphalt with polyester recycling byproduct pyrolytic carbon black, wherein 2-15% by weight of the matrix asphalt of polyester recycling byproduct pyrolytic carbon black is added to the matrix asphalt.

[0021] The polyester recycling byproduct pyrolytic carbon black is carbon black obtained by thermal cracking of polyester recycling byproducts.

[0022] In existing technologies, pyrolysis is widely used in the recycling of waste tires, but its application in polyester recycling byproducts is currently lacking. Waste tires contain polymers as well as carbon black and silica fillers. Therefore, the pyrolytic carbon black produced from the pyrolysis of waste tires is composed of several parts: some of the original carbon black filler, some derived from the original silica filler (e.g., carbon black particles coating silica particles), and some from the thermal decomposition of organic compounds. This results in a complex composition of pyrolytic carbon black. Polyester recycling byproducts have a higher content of organic compounds and virtually no carbon black particles, leading to a more homogeneous composition of pyrolytic carbon black. The inventors have discovered that filling matrix asphalt with pyrolytic carbon black from polyester recycling byproducts produces a different technical effect than filling it with pyrolytic carbon black from waste tires. The pyrolytic carbon black from polyester recycling byproducts significantly improves the viscosity, plasticity, and temperature stability of the matrix asphalt.

[0023] In this invention, there are no special requirements for the base asphalt, which can be 70# petroleum asphalt, 90# petroleum asphalt, 110# petroleum asphalt, 130# petroleum asphalt, etc.

[0024] In a preferred embodiment of the present invention, the byproducts of polyester recycling include ester byproducts and alcohol byproducts. The ester byproducts from polyester recycling contain DMT (generally not exceeding 50 wt%) and other organic compounds. The alcohol byproducts contain EG (generally not exceeding 35 wt%), small amounts of diethylene glycol, trace amounts of DMT, and other organic compounds. Therefore, both the ester and alcohol byproducts have high organic content, making them suitable for pyrolysis processing to obtain pyrolytic carbon black.

[0025] In a preferred embodiment of the present invention, the pyrolysis temperature is 400-500℃, at 1 atmosphere, in an oxygen-free or micro-oxygen environment. In this invention, polyester recycling byproducts, including ester and alcohol byproducts, can all undergo pyrolysis under oxygen-free or micro-oxygen conditions. The pyrolysis temperature can be any value selected from 400℃, 410℃, 420℃, 430℃, 440℃, 450℃, 460℃, 470℃, 480℃, 490℃, and 500℃, without particular limitation. Alternatively, the pyrolysis temperature can be further specified as 430-500℃, resulting in more complete pyrolysis of the polyester recycling byproducts.

[0026] In a preferred embodiment of the present invention, the mineral oil content in the pyrolytic carbon black does not exceed 1 ppm. The mineral oil content in the pyrolytic carbon black indicates the degree of pyrolysis; generally, the lower the mineral oil content, the more complete the pyrolysis. Furthermore, the mineral oil content in the pyrolytic carbon black does not exceed 0.5 ppm, for example, 0.5 ppm, 0.4 ppm, 0.3 ppm, 0.2 ppm, 0.1 ppm, or even lower than 0.1 ppm.

[0027] In a preferred embodiment of the present invention, the pyrolytic carbon black is pre-ground and dispersed using an air jet mill. Pyrolytic carbon black typically has a particle size in the nanometer to micrometer range, making it prone to agglomeration, which affects its performance. For example, it may exhibit poor compatibility, difficulty in dispersing in polymers, and agglomerated pyrolytic carbon black can even adversely affect the properties of asphalt. Grinding and dispersing using an air jet mill can break up the agglomerated pyrolytic carbon black and restore it to its initial particle size, thereby improving the dispersibility of pyrolytic carbon black in asphalt and achieving better results.

[0028] In a preferred embodiment of the present invention, a composition of stearate and carbon black dispersant is added as a dispersing aid during air jet milling. Adding the dispersing aid during air jet milling can more quickly disperse the pyrolytic carbon black and prevent it from re-aggregating and clustering. It also improves the compatibility of the pyrolytic carbon black with the matrix asphalt, which is beneficial for the dispersibility of the pyrolytic carbon black in the matrix asphalt and enhances the viscosity, plasticity, and temperature stability of the asphalt. The dispersing aid uses a combination of stearate and carbon black dispersant. Both stearate and carbon black dispersant are dispersants for carbon black, and carbon black dispersant has a better dispersing effect on carbon black. Stearate is solid at room temperature, while carbon black dispersant is generally liquid at room temperature; the combination of the two dispersants has a better effect. In this invention, there are no particular limitations on the stearate, which can be zinc stearate, calcium stearate, magnesium stearate, etc. There are also no particular limitations on the carbon black dispersant, which can be purchased directly from the market, such as BYK-130, BYK-161, BYK-163, BYK-9077, TEGO Dispers 685, TEGO Dispers 673, Anjeka-6161A, HZ-19079, etc. The weight ratio of stearate to carbon black dispersant in the dispersing aid can be 1:5-10:1, for example, any value from 1:5, 1:4, 1:3, 1:2, 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc., without any particular limitation. There are no particular restrictions on the combination of stearate and carbon black dispersant. One method is to heat the stearate to a molten state, for example, above the melting point of stearate, add the carbon black dispersant, and stir until homogeneous. If the carbon black dispersant contains organic solvents, some or all of the organic solvents can be removed by heating or by combining with vacuum. In this invention, the amount of dispersant added during air jet milling can be 0.5-5% of the weight of pyrolytic carbon black, or further, 0.8-3%. The dispersant can be pre-dispersed with the pyrolytic carbon black or added to the air jet mill chamber in batches.

[0029] Further preferably, the composition is in a solid state at a temperature not exceeding 40°C. Using the above technical solution, the composition is solid at room temperature, which can be dispersed into small particles and added to pyrolytic carbon black for pre-mixing, or it can be directly added to the air jet mill chamber. Under the action of the air jet mill, the composition continuously separates and coats the surface of the dispersed pyrolytic carbon black, achieving a dispersing effect. Liquid compositions at room temperature tend to agglomerate when added to pyrolytic carbon black, resulting in easier local dispersion but difficulty in dispersing throughout the entire pyrolytic carbon black. Solid compositions more easily and uniformly coat the surface of pyrolytic carbon black. In this invention, since stearate is solid at room temperature, by adjusting the weight ratio, it can be combined with a liquid carbon black dispersant at room temperature to form a solid composition.

[0030] In a preferred embodiment of the present invention, 1-5% by weight of nano-sized carbon black is further added to the base asphalt. Nano-sized carbon black particles are smaller and have a better reinforcing effect on polymers (including asphalt). In this invention, the further addition of nano-sized carbon black can synergistically enhance performance with pyrolytic carbon black, such as further improving the viscosity, plasticity, and temperature stability of the asphalt. For example, the weight of nano-sized carbon black can be any value from 1%, 2%, 3%, 4%, 5%, etc., of the base asphalt weight, without particular limitation. In this invention, the nano-sized carbon black can be directly purchased from the market, such as Cabot N330, N220, N550, N660, N774, etc. In this invention, the dispersing aids of the aforementioned pyrolytic carbon black can also disperse the nano-sized carbon black, improving the dispersibility of the nano-sized carbon black in the base asphalt.

[0031] In a more preferred embodiment of the present invention, the weight ratio of pyrolytic carbon black to nano-sized carbon black is 1:1 to 10:1. For example, the weight ratio of pyrolytic carbon black to nano-sized carbon black can be any value from 1:1, 2:1, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1, 9:1, 10:1, etc., without particular limitation. Further, the weight ratio of pyrolytic carbon black to nano-sized carbon black can be 3:1 to 10:1.

[0032] In a preferred embodiment of the present invention, one or a combination of two or more of the following are added to the base asphalt: an antioxidant, a toughening agent, a UV stabilizer, a viscosity modifier, aggregates, and a tackifier. For example, the antioxidant may be antioxidant 4010, antioxidant CPPD, etc.; the toughening agent may be SBS, SEBS, etc.; the UV stabilizer may be UV326, UV327, UV328, UV329, etc.; the viscosity modifier may be methyl laurate, ethyl laurate, methyl n-octanoate, ethyl n-octanoate, etc.; the aggregate may be sand and gravel of different particle sizes, such as 0.5-10 mm; and the tackifier may be C5-C9 petroleum resin, rosin resin, etc.

[0033] The technical solution of the present invention will be further described and illustrated below with reference to various embodiments. Unless otherwise specified, the parts mentioned in the following embodiments are parts by weight.

[0034] In the following embodiments, pyrolytic carbon black ① is derived from ester byproducts. Specifically, the ester byproducts, after testing, consisted of 41% DMT by weight, with the remainder mainly being other organic compounds. After melting the ester byproducts at 100°C, preheating at 180°C, and thermally decomposing at 450°C, the collected products contained 91% non-condensable gases by weight and 9% pyrolytic carbon black ① by weight. The mineral oil content in pyrolytic carbon black ① was less than 0.1 ppm.

[0035] Pyrolytic carbon black ② originates from alcohol byproducts. Specifically, the alcohol byproducts, after testing, consist of: ethylene glycol (22% by weight), diethylene glycol (5% by weight), polyethylene terephthalate (BHET) (2% by weight), BHET dimer (1% by weight), and the remaining components are mainly other organic compounds. After heating to 80℃, preheating to 170℃, and thermally decomposing at 440℃, the collected products contain 27% non-condensable gases, 63% mineral oil, and 10% pyrolytic carbon black 2. The mineral oil content in pyrolytic carbon black 2 is less than 0.1 ppm.

[0036] Example 1

[0037] Eight parts of the above-mentioned pyrolytic carbon black ① were added to 100 parts of 90# asphalt in four portions and mixed evenly to obtain modified asphalt.

[0038] Example 2

[0039] The difference between this embodiment and Embodiment 1 is that the pyrolytic carbon black ① in Embodiment 1 is replaced by an equal amount of dispersed pyrolytic carbon black ①-1 by weight. The remaining steps remain unchanged.

[0040] The preparation method of dispersed pyrolytic carbon black ①-1 is as follows: pyrolytic carbon black 1 is dispersed by air jet mill to obtain dispersed pyrolytic carbon black ①-1.

[0041] Example 3

[0042] The difference between this embodiment and Embodiment 1 is that the pyrolytic carbon black ① in Embodiment 1 is replaced by an equal amount of dispersed pyrolytic carbon black ①-2 by weight. The remaining steps remain unchanged.

[0043] The preparation method of dispersed pyrolytic carbon black ①-2 is as follows: Add 1 part zinc stearate and 1 part carbon black dispersant BYK-163 (by weight, based on the non-volatile components in the carbon black dispersant) to a container, heat to 140℃ and melt uniformly. After removing the organic solvent, cool and granulate into fine particles of dispersant with a particle size of approximately 0.5 mm. Mix 100 parts of pyrolytic carbon black ① and 3 parts of the above-mentioned fine particles of dispersant, mix uniformly in a mixer, and disperse using an air jet mill to obtain dispersed pyrolytic carbon black ①-2.

[0044] Example 4

[0045] The difference between this embodiment and Embodiment 3 is that in Embodiment 3, pyrolytic carbon black ①-2 is replaced by an equal weight of dispersed pyrolytic carbon black ①-3. The remaining steps remain unchanged.

[0046] The preparation method of dispersed pyrolytic carbon black ①-3 is as follows: In the preparation of dispersed pyrolytic carbon black ①-2 in Example 3, the amount of zinc stearate was adjusted from 1 part to 5 parts. The remaining steps remained unchanged.

[0047] Example 5

[0048] The difference between this embodiment and Embodiment 3 is that in Embodiment 3, 2 parts of carbon black N330 were added to the 90# asphalt. The remaining steps remain unchanged.

[0049] Example 6

[0050] The difference between this embodiment and Embodiment 5 is that in Embodiment 5, the amount of carbon black N330 is increased from 2 parts to 4 parts. The remaining steps remain unchanged.

[0051] Example 7

[0052] The difference between this embodiment and Embodiment 3 is that in Embodiment 3, 3 parts of dispersant were replaced with 3 parts of zinc stearate. The remaining steps remain unchanged.

[0053] Example 8

[0054] The difference between this embodiment and Embodiment 3 is that in Embodiment 3, 3 parts of dispersing agent were replaced with 3 parts of carbon black dispersant BYK-163. The remaining steps remain unchanged.

[0055] Comparative Example 1

[0056] Unmodified 90# asphalt.

[0057] Comparative Example 2

[0058] The difference between this comparative example and Example 1 is that in Example 1, pyrolytic carbon black ① is replaced with an equal weight of carbon black obtained from the pyrolysis of waste tires. The carbon black obtained from the pyrolysis of waste tires is obtained by pyrolyzing waste tires at 450°C. The remaining steps remain unchanged.

[0059] Example 9

[0060] Add 1 part calcium stearate and 2 parts carbon black dispersant BYK-9077 to a container, heat to 140℃ and melt evenly, cool and granulate into fine particles of dispersant with a particle size of about 0.2 mm. Add 100 parts pyrolytic carbon black ② and 2 parts of the above-mentioned fine particles of dispersant to a mixer and mix evenly, and disperse using an air jet mill to obtain dispersed pyrolytic carbon black ②-1.

[0061] Add 2 parts of the above-mentioned pyrolytic carbon black ②-1 to 100 parts of 90# asphalt in 3 portions, mix and stir evenly, then add 2 parts of methyl laurate, 5 parts of sand and gravel with an average particle size of 0.5 mm and 10 parts of sand and gravel with an average particle size of 4 mm, and stir and mix evenly to obtain modified asphalt.

[0062] Example 10

[0063] The difference between this embodiment and Embodiment 9 is that in Embodiment 9, the amount of pyrolytic carbon black ②-1 is increased from 2 parts to 5 parts. The remaining steps remain unchanged.

[0064] Example 11

[0065] The difference between this embodiment and Embodiment 9 is that in Embodiment 9, the amount of pyrolytic carbon black ②-1 is increased from 2 parts to 10 parts. The remaining steps remain unchanged.

[0066] Example 12

[0067] The difference between this embodiment and Embodiment 9 is that in Embodiment 9, the amount of pyrolytic carbon black ②-1 is increased from 2 parts to 15 parts. The remaining steps remain unchanged.

[0068] Example 13

[0069] The difference between this embodiment and Embodiment 11 is that in Embodiment 11, 1 part of carbon black N660 is added simultaneously with pyrolytic carbon black ②-1. The remaining steps remain unchanged.

[0070] Example 14

[0071] The difference between this embodiment and Embodiment 13 is that in Embodiment 13, the amount of carbon black N660 is increased from 1 part to 2 parts. The remaining steps remain unchanged.

[0072] Performance testing

[0073] Viscosity: The penetration of the asphalt was tested according to GB / T 4508 "Determination of Ductility of Asphalt", at 25℃ and 0.1 mm. The lower the penetration, the higher the viscosity of the asphalt.

[0074] Plasticity: The elongation of the asphalt was tested according to ASTM D 113-1986. The asphalt was made into a figure-eight shaped standard specimen and stretched at 5 cm / min at 10°C to the length at which it broke. The greater the elongation, the better the plasticity of the asphalt.

[0075] Temperature stability: The softening point of the asphalt to be tested is determined according to standard JTG / T 3364-02-2019. The higher the softening point, the better the temperature stability.

[0076] The specific test structure is shown in Table 1 below.

[0077] Table 1

[0078]

[0079]

[0080] As can be seen from the data in Table 1 above, the use of pyrolytic carbon black, a byproduct of polyester recycling, as a modifier for asphalt in this invention can improve the viscosity, plasticity, and temperature stability of asphalt, and has a good application effect. This is a major breakthrough in resource recycling.

[0081] As described above, the basic principles, main features, and advantages of the present invention have been shown and described. Those skilled in the art should understand that the present invention is not limited to the above embodiments, which are merely preferred embodiments and should not be construed as limiting the scope of the invention. All equivalent changes and modifications made in accordance with the scope of the patent and the description should still fall within the scope of the present invention. The scope of protection of this invention is defined by the appended claims and their equivalents.

Claims

1. A method of improving pitch with polyester recycling by-product pyrolytic carbon black, characterized by, The polyester recycling byproduct pyrolysis carbon black is obtained by pyrolysis of the byproduct of polyester recycling. The polyester recycling byproduct pyrolysis carbon black is obtained by pyrolysis of the byproduct of polyester recycling.

2. The method of improving pitch with polyester recycling byproduct pyrolytic carbon black according to claim 1, characterized in that, The polyester recycling byproduct pyrolysis carbon black is obtained by pyrolysis of the byproduct of polyester recycling.

3. The method of improving pitch with polyester recycling byproduct pyrolytic carbon black according to claim 1, characterized in that, The polyester recycling byproduct pyrolysis carbon black is obtained by pyrolysis of the byproduct of polyester recycling.

4. The method of improving pitch with polyester-recycle byproduct pyrolytic carbon black of claim 1, wherein, The temperature of the pyrolysis is 400-500℃ under 1 atmosphere and in an oxygen-free or micro-oxygen environment.

5. The method of improving pitch with polyester-recycle byproduct pyrolytic carbon black of claim 1, wherein, The content of mineral oil in the pyrolysis carbon black is not more than 1ppm.

6. The method of improving pitch with polyester-recycle byproduct pyrolytic carbon black according to claim 5, characterized in that, The pyrolysis carbon black is pre-milled and dispersed by using an air flow mill.

7. The method of improving pitch with polyester-recycle byproduct pyrolytic carbon black according to claim 6, characterized in that, A composition of stearate and carbon black dispersant is added as a dispersion aid during the air flow mill dispersion.

8. The method of improving pitch with polyester-recycle byproduct pyrolytic carbon black of claim 1, wherein, The composition is in solid state at a temperature not more than 40℃.

9. The method of improving pitch with polyester-recycle byproduct pyrolytic carbon black of claim 8, wherein, The base asphalt also contains 1-5% of nano-sized carbon black by weight of the base asphalt.

10. The method of improving pitch with polyester recycling byproduct pyrolytic carbon black of claim 1, wherein, The weight ratio of the pyrolysis carbon black to the nano-sized carbon black is 1:1-10:

1. The base asphalt also contains one or a combination of two or more of an antioxidant, a toughening agent, an ultraviolet resistant agent, a viscosity regulator, a mineral aggregate and a tackifier.

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