CN110723928A

CN110723928A - High-performance rubber asphalt mixture, preparation method and application thereof

Info

Publication number: CN110723928A
Application number: CN201810785171.8A
Authority: CN
Inventors: 江宽; 董大伟; 董常乐; 刘双旺; 李田田; 马庆杰; 郭敬伟; 王重阳; 高云龙; 冯亚琴; 刘晓楠; 董进学
Original assignee: Rood Yongtai Beijing Environmental Protection Technology Co Ltd
Current assignee: Rood Yongtai Beijing Environmental Protection Technology Co Ltd
Priority date: 2018-07-17
Filing date: 2018-07-17
Publication date: 2020-01-24

Abstract

The invention provides a high-performance rubber asphalt mixture, a preparation method and application thereof. The high-performance rubber asphalt mixture comprises high-viscosity rubber asphalt and aggregate, wherein the high-viscosity rubber asphalt comprises asphalt, a modifier and a first crosslinking aid, the raw materials of the modifier comprise linearized active rubber, an olefin polymer with the molecular weight of 3000-7000 and the melting point of 90-125 ℃ and a second crosslinking aid, the linearized active rubber is obtained by desulfurization treatment of waste rubber powder, and the weight percentage content of linearized molecules in the linearized active rubber is more than or equal to 75%. The high-performance rubber asphalt mixture has a series of performance characteristics of excellent high-temperature resistance (high-temperature rutting resistance), water damage resistance stability, low-temperature cracking resistance, production workability and the like, is very suitable for being used as a high-grade asphalt pavement material, is particularly suitable for laying OGFC (one glass cement fiber reinforced plastics) open-graded drainage asphalt pavements, and can effectively reduce the cost of the laying material.

Description

High-performance rubber asphalt mixture, preparation method and application thereof

Technical Field

The invention relates to the technical field of asphalt pavement material modification, in particular to a high-performance rubber asphalt mixture, and a preparation method and application thereof.

Background

High grade asphalt pavement materials are typically prepared from high viscosity modified asphalt, the properties of which are important factors affecting the quality of the final pavement, and aggregate.

Two important indicators of high viscosity modified asphalt are dynamic viscosity at 60 ℃ (usually required to be more than or equal to 50000pa.s) and Brookfield rotary viscosity at 135 ℃ (usually required to be less than 3 pa.s), and some other performance indicators are shown in Table 1 (JT/T860.2-2013). The viscosity of asphalt is essentially a measure of the ability of asphalt to resist relative displacement between molecules, asphalt with high viscosity is not easy to displace between molecules, and asphalt is not easy to deform and has higher stiffness. The higher viscosity indicates that the asphalt is used as a binding material to bind loose aggregates into a whole, and the aggregates are not easy to displace under the action of external force, so that the asphalt has higher strength and shear flow deformation resistance.

The viscosity of the asphalt is reduced along with the increase of the temperature, and the asphalt pavement is easy to generate permanent deformation under the action of vehicle load in summer to form ruts and jostles, so that the service performance of the road is sharply reduced, and the threat to traffic safety is caused. The maximum temperature of asphalt pavement in summer in many areas tends to reach or exceed 60 ℃, which is a dangerous temperature causing deformation of the pavement, and therefore the high temperature deformation resistance of asphalt can be characterized by a viscosity of 60 ℃. The adhesion force of the asphalt and the aggregate is mainly composed of van der waals force, ionic force, mechanical bonding force (formed after the high-temperature asphalt permeates into micropores on the surface of the mineral aggregate and is cooled) and the like, and the mechanical bonding force is strengthened due to the high viscosity of the asphalt, so that the bonding capability of the asphalt to the aggregate is improved, and the water damage resistance of the asphalt is improved. The dynamic viscosity at 60 ℃ of the high-viscosity modified asphalt with the performance up to the standard is high, but the Brookfield rotary viscosity at 135 ℃ is still below 3pa.s, which shows that the high-viscosity modified asphalt still has good workability and construction rolling performance at high temperature.

TABLE 1

The high-viscosity modified asphalt is suitable for paving high-modulus and extremely-hot-area road surfaces, and is particularly suitable for construction and paving open-graded/semi-open-graded permeable asphalt road surfaces. For the above characteristics, many related researches are conducted at home and abroad. CN1990557A discloses a high viscosity modified asphalt, which comprises the following components: 100 parts of asphalt, 3-12 parts of styrene-isoprene-styrene (SIS) block copolymer with the average molecular weight of 3-30 ten thousand, 5-40 parts of petroleum resin with the softening point of 70-150 ℃ and 0.05-1 part of sulfur. Patent CN102838874A discloses an asphalt modifier, modified asphalt and asphalt mixture. The modifier comprises the following components: 3-10 parts of waste tire rubber powder, 3-10 parts of polyethylene waste, 3-8 parts of styrene-butadiene-styrene block copolymer, 1-5 parts of styrene-isoprene-styrene block copolymer, 1-5 parts of terpene resin, 5-10 parts of solvent oil and 0.3-0.7 part of alcohol ether carboxylate interface agent. The modified asphalt comprises the following raw materials: 70-80 parts of matrix asphalt, 15-30 parts of asphalt modifier and 0.05-0.4 part of stabilizer. Patent CN106800787A discloses a high-temperature storage-resistant high-viscosity high-elasticity modified asphalt and a preparation method thereof. The raw materials comprise: 100 parts of matrix asphalt, 6-15 parts of waste rubber powder (40-80 meshes), 3.5-6 parts of SBS, 1-3 parts of EVA, 0.5-3 parts of coupling agent, 0.5-2 parts of compatilizer, 0.2-0.6 part of cross-linking agent and 0.5-1.5 parts of anti-aging agent. Similar methods also CN107163594A, CN105315686A, CN104151846A, etc.

However, the existing preparation method of high-viscosity modified asphalt has the following defects:

(1) the core modification auxiliary agent adopts a high molecular polymer modifier synthesized by a chemical method, such as SIS, and the addition amount is large, so that the cost of the high-viscosity modified asphalt is high; the waste tire rubber powder is compounded with partial high molecular polymer, such as high molecular resin, SBS elastomer, EVA elastomer and partial interface compatilizer, as the modifier, although the cost of the high-viscosity modified asphalt can be reduced to a certain extent, the cost reduction range is limited because the mixing ratio of the rubber powder is low;

(2) the rubber powder is adopted for modification, and the characteristics of linear macromolecular rubber/resin are not fully exerted in modified asphalt: on one hand, the rubber powder absorbs light components of the asphalt to thicken a modified asphalt system, so that the adhesiveness of the modified asphalt is increased, but the increase of the system is only limited to good coating performance of stone materials and relatively high molecular weight components in the asphalt; on the other hand, the rubber powder exists in a granular state in a modified asphalt system, and serves as a stress concentration point in asphalt, so that the contribution to the cohesive force of high-viscosity modified asphalt is insufficient;

(3) the adding proportion of the rubber powder is generally concentrated in 3-20 parts, meanwhile, a part of macromolecular elastomer/resin is compounded, according to the indexes accepted by the industry, the high-temperature viscosity (180 ℃) of the blended modified asphalt is higher than 1.5 pa-s, which means that the Brookfield viscosity at 135 ℃ is at least higher than 5 pa-s, and the index is far away from the standard requirement of the high-viscosity modified asphalt, which means that the construction workability of the modified asphalt is greatly influenced;

(4) the dynamic viscosity at 60 ℃ of the modified asphalt is larger than 100000pa.s, the dynamic viscosity at 60 ℃ is measured by adopting a capillary method, the diameter of the capillary is in the range of 0.125-8mm, the modified asphalt prepared by the method has a large amount of rubber powder, the rubber powder has great influence on the viscous resistance of asphalt fluid, and the measured data is not true dynamic viscosity of the modified asphalt, namely the cohesion (toughness/toughness) of the modified asphalt can not be truly reflected.

For this reason, the high-performance rubber asphalt mixture used for paving asphalt pavement in the prior art has the problems of high material cost or substandard performance.

Disclosure of Invention

The invention mainly aims to provide a high-performance rubber asphalt mixture, a preparation method and application thereof, and aims to solve the problems that the preparation cost of the high-performance rubber asphalt mixture for paving an asphalt pavement is high or the performance is unqualified in the prior art.

In order to achieve the above object, according to one aspect of the present invention, a high performance rubber asphalt mixture is provided, which includes high viscosity rubber asphalt and aggregate, wherein the high viscosity rubber asphalt includes asphalt, a modifier and a first crosslinking assistant, the modifier includes a linearization active rubber, an olefin polymer with a molecular weight of 3000-7000 and a melting point of 90-125 ℃, and a second crosslinking assistant, the linearization active rubber is obtained by desulfurization treatment of waste rubber powder, and the weight percentage content of linearization molecules in the linearization active rubber is greater than or equal to 75%.

Further, the linearized active rubber is prepared by one of the following methods:

firstly, placing a mixture of waste rubber powder and a photocatalyst in supercritical carbon dioxide under ultraviolet light for photocatalytic desulfurization reaction to obtain linear active rubber; preferably, the photocatalyst is a composite inorganic photocatalyst; more preferably, the photocatalyst is selected from Co-doped TiO₂、ZrO₂/ZnO composite and ZrO₂/TiO₂One or more of the complexes; further preferably, the amount of the photocatalyst is 0.5-3% of the weight of the waste rubber powder;

secondly, pretreating the waste rubber powder and a regenerant at the temperature of 60-150 ℃ for 10-30 min, and standing at the temperature of 50-120 ℃ for 6-36 h to obtain a pretreated product; extruding the pretreated product in a screw extruder, wherein the extrusion temperature is 100-480 ℃, the extrusion pressure is 3-15 Mpa, and the reaction time is 1-15 min to obtain the linear active rubber; preferably, the regenerant comprises a softener selected from one or more of coal tar, pine tar, tall oil, naphthenic oil, dipentene, paraffin oil, oleic acid and rosin, and an activator selected from one or more of aromatic disulfide, polyalkylphenol sulfide, phenyl mercaptan and n-butylamine; preferably, the weight ratio of the waste rubber powder to the softener to the activator is 100: (5-30): (0.5 to 5);

thirdly, placing the waste rubber powder into a vertical depolymerizer, adding a solvent, a desulfurization catalyst and a cocatalyst, and then performing desulfurization reaction at the temperature of 160-180 ℃ and under the pressure of 0.5-0.7 MPa to obtain linear active rubber; wherein the solvent is paraffin oil and/or solid coumarone, the desulfurization catalyst is phthalic anhydride, and the cocatalyst is formalin and/or resorcinol.

Furthermore, in the linearized active rubber, the weight percentage content of the linearized macromolecules with the molecular weight of 20000-70000 is more than or equal to 80%.

Further, the olefin polymer is one or more of polyethylene wax, oxidized polyethylene wax, sasobit wax and polyamide wax; preferably the olefin polymer is polyethylene wax; further preferably, the polyethylene wax is made by degradation of waste plastics.

The raw materials of the modifier further comprise petroleum resin, preferably the petroleum resin is one or more of C5 petroleum resin, C9 petroleum resin, phenolic resin and terpene resin, and more preferably, the raw materials of the modifier comprise 55-85 parts by weight of linearized active rubber, 10-30 parts by weight of olefin polymer, 0.3-2 parts by weight of second crosslinking assistant and 5-15 parts by weight of petroleum resin.

Further, the first crosslinking auxiliary agent is one or more of sulfur, promoter M, TMTD, promoter D, zinc oxide and stearic acid; preferably, the second crosslinking assistant is one or more of n-butyl-4, 4-di (tert-butylperoxy) valerate, dicumyl peroxide, maleic anhydride and phthalic anhydride; preferably, the asphalt is one or more of petroleum asphalt, coal asphalt and natural asphalt.

Further, the high-viscosity rubber asphalt further includes an elastomeric polymer; preferably, the elastomeric polymer is one or more of SBS, SEBS, SIS, SBR, EVA, and POE.

Further, the high-viscosity rubber asphalt comprises, by weight, 100 parts of asphalt, 25-50 parts of a modifier, 0.2-2 parts of a first crosslinking aid and 0-3 parts of an elastomer polymer.

According to another aspect of the present invention, there is also provided a method for preparing a high-performance rubber asphalt mixture, comprising the steps of: banburying and mixing the linear active rubber, the olefin polymer and the second crosslinking assistant to obtain a premix; carrying out extrusion molding and grain cutting on the premix to obtain a modifier; mixing the modifier, the asphalt and the first crosslinking assistant to obtain high-viscosity rubber asphalt; and mixing the high-viscosity rubber asphalt with the aggregate to obtain the high-performance rubber asphalt mixture.

Further, during the banburying and mixing process, petroleum resin is added simultaneously; preferably, the mixing temperature in the banburying mixing process is 80-140 ℃, and the mixing time is 10-30 min; preferably, the extrusion temperature in the extrusion molding process is 130-220 ℃, and the extrusion speed is 20-100 rpm.

Further, in the step of mixing the modifier, the asphalt and the first crosslinking assistant, the elastomeric polymer is added simultaneously.

Further, the step of mixing the modifier, the asphalt, the first crosslinking aid, and the elastomeric polymer comprises: heating asphalt to 170-190 ℃, then mixing the asphalt with an elastomer polymer, and stirring for 30-60 min under the condition of heat preservation to obtain a mixture A; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm; mixing the mixture A with a modifier, and stirring for 60-120 min under the condition of heat preservation to obtain a mixture B; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm; carrying out circulating shearing and grinding on the mixture B to obtain a mixture C; preferably, the grinding temperature in the step is 170-190 ℃, and the grinding rotating speed is 5000-10000 rpm; mixing the mixture C with a first crosslinking auxiliary agent, and stirring for 30-60 min under the condition of heat preservation to obtain high-viscosity rubber asphalt; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm.

According to another aspect of the invention, the application of the high-performance rubber asphalt mixture as an asphalt pavement material is also provided.

Further, the high-performance rubber asphalt mixture is used as an AC type continuous close-graded structure asphalt mixture, an SMA type asphalt mastic structure asphalt mixture and an OGFC type open-graded drainage asphalt mixture.

The invention provides a high-performance rubber asphalt mixture which comprises high-viscosity rubber asphalt and aggregate, wherein the high-viscosity rubber asphalt comprises asphalt, a modifier and a first crosslinking aid, the raw materials of the modifier comprise linearized active rubber, an olefin polymer with the molecular weight of 3000-7000 and the melting point of 90-125 ℃ and a second crosslinking aid, the linearized active rubber is obtained by desulfurization treatment of waste rubber powder, and the weight percentage content of linearized molecules in the linearized active rubber is more than or equal to 75%. Different from the traditional modified asphalt added with rubber powder, the high-viscosity rubber asphalt adopted in the high-performance rubber asphalt mixture of the invention is added with a modifier comprising linear active rubber, olefin polymer and a second crosslinking assistant besides an asphalt component and a first crosslinking assistant component. The asphalt is modified by the special modifier to prepare the high-viscosity rubber asphalt, so that the material cost of the high-viscosity rubber asphalt can be effectively reduced, and the material cost of the high-performance rubber asphalt mixture can be effectively reduced. Meanwhile, the high-viscosity rubber asphalt has higher dynamic viscosity at 60 ℃ and higher toughness/toughness, the high-temperature viscosity is still less than or equal to 3pa.s, and other physical and chemical properties meet the index requirements of JT/T860.2-2013. Therefore, the high-performance rubber asphalt mixture prepared by the high-viscosity rubber asphalt and the aggregate also has a series of performances such as high temperature resistance, water damage resistance stability, low temperature cracking resistance, production workability and the like, is very suitable for being used as a high-grade asphalt pavement material, is particularly suitable for being used for paving an OGFC (open graded asphalt pavement) type open-graded drainage asphalt pavement, and can further reduce the cost of the paving material.

Detailed Description

It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict. The present invention will be described in detail with reference to examples.

The present application is described in further detail below with reference to specific examples, which should not be construed as limiting the scope of the invention as claimed.

As described in the background section, the high performance rubber asphalt mixtures used in the prior art for paving asphalt pavement have problems of high material cost or unacceptable performance.

In order to solve the problems, the invention provides a high-performance rubber asphalt mixture which comprises high-viscosity rubber asphalt and aggregate, wherein the high-viscosity rubber asphalt comprises asphalt, a modifier and a first crosslinking aid, the raw materials of the modifier comprise linearized active rubber, an olefin polymer with the molecular weight of 3000-7000 and the melting point of 90-125 ℃ and a second crosslinking aid, the linearized active rubber is obtained by desulfurization treatment of waste rubber powder, and the weight percentage content of linearized molecules in the linearized active rubber is more than or equal to 75%.

Different from the traditional modified asphalt added with rubber powder, the high-viscosity rubber asphalt adopted in the high-performance rubber asphalt mixture of the invention is added with a modifier comprising linear active rubber, olefin polymer and a second crosslinking assistant besides an asphalt component and a first crosslinking assistant component.

Different from rubber powder, the weight percentage content of the linear molecules in the linear active rubber adopted by the invention is more than or equal to 75%, and when the linear active rubber is applied to high-viscosity rubber asphalt, the advantages of the macromolecules can be fully exerted, the cohesion of the modified asphalt is fully improved, and the toughness and the viscotoughness of the modified asphalt are improved. After the waste rubber powder is subjected to desulfurization treatment, the molecular weight of the obtained linear active rubber is reduced by at least one order of magnitude compared with the molecular weight of the rubber powder, the molecular weight of the high-molecular elastomer (SBS, EVA, SBR and the like) and the molecular weight of the high-molecular resin, and the linear active rubber can be added in a large proportion without influencing the high-temperature viscosity (135 ℃ Brookfield viscosity) of the modified asphalt when being applied to the high-viscosity rubber asphalt, so that the material cost of the high-viscosity rubber asphalt can be effectively reduced. Meanwhile, the chain end of the linear active rubber is grafted with partial active functional groups due to regeneration, the active functional groups can be coupled with a polar structure in the asphalt, so that the linear active rubber can stably exist in the asphalt without layering and segregation, the affinity of the active functional groups and stone is good, a good coating effect can be formed, and the toughness of the modified asphalt is improved. In addition, the linearization active rubber does not exist in particles like rubber powder, and the application of the linearization active rubber in the high-viscosity rubber asphalt can reduce the formation of stress concentration points, thereby improving the comprehensive physical properties of the high-viscosity rubber asphalt, such as high-temperature softening point, low-temperature ductility and the like. And the linearized active rubber is prepared by desulfurization and degradation of waste rubber, wherein the carbon black and the anti-aging agent are partially in a free state, so that the anti-aging effect of the modified asphalt can be improved to a certain extent.

The olefin polymer with the molecular weight of 3000-7000 and the melting point of 90-125 ℃ has the characteristics of high molecular resin, such as high melting point, high crystallinity, good high-temperature strength, weak low-temperature flexibility and the like, and the capability of absorbing light components in the modified asphalt is greatly weakened due to the low molecular weight, so that the high-temperature viscosity of the modified asphalt can be not influenced by the addition of a larger proportion, and the cost of the modified asphalt is greatly reduced. More importantly, under the action of the crosslinking assistant, the linearized active rubber and the olefin polymer can form a high molecular polymer with dual characteristics of an elastomer and a resin in a weak chemical combination mode, and the chain end of the linearized active rubber has an active functional group, so that the linearized active rubber and the olefin polymer can form good dispersion in the modified asphalt. Therefore, the elasticity and low-temperature flexibility of the linearized active rubber and the high-temperature toughness of the olefin polymer can be simultaneously exerted, so that the high-viscosity rubber asphalt has the characteristics of excellent high-temperature strength, low-temperature flexibility, elasticity and the like. In addition, the molecular weight of the combination of the linearized active rubber and the olefin polymer is still low, and the value of the macromolecule is still at least one grade lower than that of the high molecular elastomer, so that the capability of absorbing light components of asphalt is weaker, and the high-temperature viscosity (135 ℃ Brookfield viscosity) of the modified asphalt can be increased by adding the linearized active rubber in a large proportion. More particularly, the addition of a large proportion of a combination of a linearized reactive rubber and an olefin polymer to a modified asphalt increases the average molecular weight of the modified asphalt to a greater extent. The asphalt and colloid components in the four components of the asphalt have the largest contribution to the coating property and the coating strength of the asphalt and stone, and the important reason is that the molecular weight of the asphalt is larger and the cohesive force of an asphalt film formed by coating the asphalt and aggregate is larger. Therefore, increasing the molecular weight of asphalt/modified asphalt to some extent is an important means to improve the cohesion (coating strength) of modified asphalt. The large-proportion addition of the combination can realize the great increase of the average molecular weight of the modified asphalt, and then can obviously increase the cohesive force (wrapping strength) of the modified asphalt, and the modified asphalt has higher dynamic viscosity at 60 ℃ and higher toughness/toughness in performance indexes.

In a word, the invention modifies the asphalt by the special modifier to prepare the high-viscosity rubber asphalt, which can effectively reduce the material cost of the high-viscosity rubber asphalt and further can effectively reduce the material cost of the high-performance rubber asphalt mixture. Meanwhile, the high-viscosity rubber asphalt has higher dynamic viscosity at 60 ℃ and higher toughness/toughness, the high-temperature viscosity is still less than or equal to 3pa.s, and other physical and chemical properties meet the index requirements of JT/T860.2-2013. Therefore, the high-performance rubber asphalt mixture prepared by the high-viscosity rubber asphalt and the aggregate also has a series of performances such as high-temperature resistance, low-temperature cracking resistance (low-temperature flexibility provided by linearized rubber), water damage resistance stability, production workability and the like, is very suitable for being used as a high-grade asphalt pavement material, is particularly suitable for being used for paving an OGFC (open graded draining asphalt) type asphalt pavement, and can further reduce the cost of the paving material.

The linearized active rubber can be prepared by performing physical shearing desulfurization or high-temperature boiling degradation on waste rubber powder, and is preferably prepared by the following steps:

physical shearing desulfurization:

in a preferred embodiment, the waste rubber powder and the regenerant are pretreated at the temperature of 60-150 ℃ for 10-30 min and then are kept stand at the temperature of 50-120 ℃ for 6-36 h to obtain a pretreated product; extruding the pretreated product in a screw extruder, wherein the extrusion temperature is 100-480 ℃, the extrusion pressure is 3-15 Mpa, and the reaction time is 1-15 min to obtain the linear active rubber; preferably, the regenerant comprises a softener selected from one or more of coal tar, pine tar, tall oil, naphthenic oil, dipentene, paraffin oil, oleic acid and rosin, and an activator selected from one or more of aromatic disulfide, polyalkylphenol sulfide, phenyl mercaptan and n-butylamine; preferably, the weight ratio of the waste rubber powder to the softener to the activator is 100: (5-30): (0.5-5).

Degradation by a high-temperature boiling method:

in a preferred embodiment, waste rubber powder is placed in a vertical depolymerizer, a solvent, a desulfurization catalyst and a cocatalyst are added, and then desulfurization reaction is carried out at the temperature of 160-180 ℃ and under the pressure of 0.5-0.7 MPa to obtain linear active rubber; wherein the solvent is paraffin oil and/or solid coumarone, the desulfurization catalyst is phthalic anhydride, and the cocatalyst is formalin and/or resorcinol.

Compared with the physical shearing desulfurization or high-temperature boiling degradation, the more preferable linear active rubber is prepared by adopting the following method:

in a preferred embodiment, the linearized active rubber is prepared by the following process: in supercritical carbon dioxide, the mixture of waste rubber powder and photocatalyst is put under ultraviolet light for photocatalytic desulfurization reaction to obtain the linearized active rubber. The waste rubber powder can be swelled by using the supercritical carbon dioxide, so that the aperture of the three-dimensional cross-linked network in the waste rubber powder is increased, and the photocatalyst is permeated into the waste rubber powder from the surface by virtue of the diffusion effect of the supercritical carbon dioxide fluid. Secondly, the photocatalyst generates a large amount of active groups under the irradiation of ultraviolet light to catalyze the breakage of S-S bonds in the waste rubber powder, thereby realizing the desulfurization and crosslinking of the waste rubber powder. Particularly, since the supercritical carbon dioxide also has an excellent dissolving effect, the linear molecules formed by the desulfurization and de-crosslinking on the surface of the waste rubber powder can be rapidly peeled off from the surface of the waste rubber powder and dissolved in the supercritical carbon dioxide. Along with the continuous reaction, the waste rubber powder continuously carries out the cyclic reciprocating of 'catalyst surface permeation, photocatalytic desulfurization and desulfurization linear molecule stripping dissolution' until the waste rubber powder integrally completes desulfurization and de-crosslinking to form the linear active rubber.

Different from the mechanical shearing desulfurization regeneration method, the photocatalytic desulfurization is carried out under the swelling action of supercritical carbon dioxide, so that the method has higher selectivity on the breaking point of a cross-linked network, and the breaking point is mostly at the S-S bond cross-linking part. While the breaking point of mechanical shear desulfurization is a diversified breaking point that is not selective for S-S bond crosslinks. Therefore, based on the preparation method, the linearized structure of the rubber can be maintained more completely, the regenerated linearized active rubber has relatively high molecular weight, the rubber flexibility and elasticity can be more fully exerted, the 60 ℃ dynamic viscosity of the high-viscosity rubber asphalt can be further improved, and meanwhile, the molecular weight is still reduced by at least one order of magnitude compared with high-molecular elastomers such as SBS, SIS and the like, so that the high-viscosity rubber asphalt still has relatively low high-temperature viscosity under the condition of large-proportion addition, and the comprehensive performance of the rubber asphalt mixture can be further improved.

Compared with the mode of degradation by a high-temperature boiling method, the photocatalytic desulfurization is carried out under the swelling action of the supercritical carbon dioxide without adding a chemical desulfurizer, so that the problems of delayed vulcanization, secondary degradation and the like caused by chemical desulfurization and residue are avoided. Meanwhile, a large amount of softening additives are not added to the high-temperature boiling method, so that the influence of the softening additives on the performance of the asphalt is avoided, the high-viscosity rubber asphalt has higher performance, and the comprehensive performance of the rubber asphalt mixture is correspondingly improved.

The above-mentioned photocatalyst may be of a type commonly used in the field of photocatalytic technology. In a preferred embodiment, the photocatalyst is a composite inorganic photocatalyst. The composite inorganic photocatalyst has higher catalytic activity and higher selective fracture performance on S-S crosslinking points in the waste rubber powder. More preferably, the photocatalyst is selected from Co-doped TiO₂、ZrO₂/ZnO composite and ZrO₂/TiO₂One or more of the complexes. The surface areas of the composite inorganic photocatalysts are greatly increased, so that the probability of exciting the photohole electrons under ultraviolet irradiation is further increased, and the composite inorganic photocatalysts have higher catalytic activity. Meanwhile, the photocatalysts are remained in the linearized active rubber and can be used as fillers of the modified asphalt to play an auxiliary role.

In a preferred embodiment, the preparation method comprises the following steps: mixing waste rubber powder with a photocatalyst to obtain a mixture; under the condition of stirring, putting the mixture into supercritical carbon dioxide for swelling treatment to obtain a swelling mixture; and irradiating ultraviolet light to the swelling mixture in supercritical carbon dioxide to perform photocatalytic desulfurization reaction, thereby obtaining the linearized active rubber. Thus, mixing the waste rubber powder with the photocatalyst in advance enables the photocatalyst to be dispersed in the waste rubber powder in advance. Secondly, the mixture is placed in supercritical carbon dioxide under the condition of stirring for swelling treatment, so that the diffusion effect of supercritical carbon dioxide fluid can be more fully exerted, the waste rubber powder is swelled as soon as possible, and the photocatalyst is enabled to permeate into the surface of the waste rubber powder more quickly. Finally, irradiating ultraviolet light to the system for photocatalytic desulfurization reaction. In the actual operation process, the desulfurization efficiency of the waste rubber powder can be further improved according to the process.

In a preferred embodiment, the swelling treatment step comprises: injecting carbon dioxide gas into a system in which the mixture is located, and then adjusting the temperature of the system to 80-140 ℃ and the pressure to 10-35 MPa to convert the carbon dioxide gas into a supercritical state so as to form supercritical carbon dioxide; and swelling the mixture for 30-120 min under the stirring condition that the stirring speed is 200-700 rpm, so as to obtain a swelling mixture. The swelling treatment is carried out in the technical process, the aperture of the cross-linked network of the waste rubber powder is larger, and the photocatalyst can be more fully permeated and more uniformly dispersed in the rubber network, so that on one hand, the desulfurization efficiency of the waste rubber powder can be further improved, and simultaneously, the fracture number of S-S bonds can be further improved, thereby improving the desulfurization degree of the waste rubber powder and obtaining the desulfurized rubber with higher linearization degree.

More preferably, the swelling treatment step comprises: injecting carbon dioxide gas into a system in which the mixture is located, and then adjusting the temperature of the system to 105-140 ℃ and the pressure to 28-35 MPa to convert the carbon dioxide gas into a supercritical state so as to form supercritical carbon dioxide; and swelling the mixture for 90-120 min under the condition that the stirring speed is 500-700 rpm, so as to obtain a swelling mixture. The desulfurization efficiency and desulfurization degree under the process condition are higher.

In a preferred embodiment, in the step of photocatalytic desulfurization, the reaction temperature is 80-140 ℃ and the reaction pressure is 10-35 MPa. Under the reaction conditions, the S-S bond desulfurization selectivity of the photocatalyst is higher, and the desulfurization degree and the desulfurization linearization degree of the waste rubber powder are higher. More preferably, the reaction temperature in the step of the photocatalytic desulfurization reaction is 105-140 ℃, and the reaction pressure is 28-35 MPa. In the actual production process, after the photocatalytic desulfurization reaction is finished, the method preferably further comprises the following steps: and (3) decompressing the reaction system, recovering carbon dioxide, stopping illumination and cooling to obtain the linearized active rubber.

In a preferred embodiment, in the step of photocatalytic desulfurization, the illumination time of the ultraviolet light is 5 to 30min, preferably 20 to 30min, and the wavelength of the ultraviolet light is 300 to 400nm, preferably 350 to 390 nm. Under the illumination condition, the photocatalyst has higher activity, and the desulfurization effect of the waste rubber powder is better.

In a preferred embodiment, the step of mixing the waste rubber powder with the photocatalyst comprises: and stirring and mixing the waste rubber powder and the photocatalyst for 5-30 min under the condition that the stirring speed is 700-1500 rpm to obtain a mixture. The waste rubber powder and the photocatalyst are mixed according to the process, and the waste rubber powder and the photocatalyst can be mutually dispersed more fully. Preferably, the waste rubber powder and the photocatalyst are stirred and mixed to the temperature of 60-85 ℃ to obtain a mixture. Shear heating can occur in the stirring process, the stirring and mixing temperature is controlled to be 60-85 ℃, and performance influence caused by overheating can be prevented on the basis of sufficient dispersion.

As described above, based on the diffusibility and good solubility of supercritical carbon dioxide, the cyclic process of "catalyst surface permeation-photocatalytic desulfurization-desulfurization linear molecule stripping dissolution" is continuously performed in the step of photocatalytic desulfurization reaction of waste rubber powder, which enables the preparation method of the present invention to achieve a higher desulfurization degree by using the cyclic process with less photocatalyst. For the purpose of saving energy and improving the desulfurization efficiency and the desulfurization degree, in a preferred embodiment, the amount of the photocatalyst is 0.5 to 3% by weight, preferably 2 to 3% by weight, based on the waste rubber powder.

In a preferred embodiment, the particle size of the waste rubber powder is 80-120 meshes; preferably, the waste rubber powder is one or more of waste tire rubber powder, waste mechanical tire rubber powder, waste sole rubber powder and waste conveyor belt rubber powder.

In addition, the waste rubber powder can also be one or more of waste nitrile rubber powder, waste natural rubber powder, waste butyl rubber powder, waste ethylene propylene rubber powder and waste styrene-butadiene rubber powder.

In a preferred embodiment, the weight percentage of the linearized macromolecules with the molecular weight of 20000-70000 in the linearized active rubber is more than or equal to 80%. The molecular weight of the linearized active rubber is more appropriate, and the high-viscosity rubber asphalt can further improve the 60-DEG dynamic viscosity while keeping relatively low high-temperature viscosity under the condition of large-proportion addition.

In order to further increase the cohesion and high temperature strength of the high viscosity rubberized asphalt, and correspondingly improve the properties of the compound, in a preferred embodiment, the above-mentioned olefin polymers include, but are not limited to, one or more of polyethylene wax, oxidized polyethylene wax, sasobit wax and polyamide wax; preferably, the olefin polymer is polyethylene wax. The olefin polymer can further improve the comprehensive use performance of the high-viscosity rubber asphalt and correspondingly improve the performance of the mixture. Preferably, the polyethylene wax is made by degradation of waste plastics. The concrete degradation method can adopt the method in the prior art, for example, refer to the preparation method in Chinese patent CN101885857A to prepare polyethylene wax.

In a preferred embodiment, the raw material of the modifier further comprises a petroleum resin. The petroleum resin has excellent adhesiveness to stone materials, and the toughness/viscosity of the asphalt can be further improved by applying the petroleum resin as a component of a modifier to high-viscosity rubber asphalt, so that the comprehensive performance of the rubber asphalt mixture can be further improved. Preferably, the petroleum resin is one or more of C5 petroleum resin, C9 petroleum resin, phenolic resin and terpene resin.

In order to further balance the advantages of the components and further improve the comprehensive performance of the high-viscosity rubber asphalt and the mixture, in a preferred embodiment, the raw materials of the modifier comprise 55-85 parts by weight of the linearized active rubber, 10-30 parts by weight of the olefin polymer, 0.3-2 parts by weight of the second crosslinking assistant and 5-15 parts by weight of the petroleum resin.

Preferably, the first crosslinking assistant is one or more of sulfur, promoter M, TMTD, promoter D, zinc oxide and stearic acid. The crosslinking aids have better crosslinking function, and are beneficial to further improving the comprehensive and reasonable performance of the high-viscosity rubber asphalt.

Preferably, the second crosslinking coagent includes, but is not limited to, one or more of n-butyl-4, 4-di (t-butylperoxy) valerate, dicumyl peroxide, maleic anhydride, and phthalic anhydride. The use of these crosslinking aids can promote the formation of more complete bonds between the linearized reactive rubber and the olefin polymer, thereby improving the dispersibility and stability of the modifier in asphalt.

Preferably, the asphalt is one or more of petroleum asphalt, coal asphalt and natural asphalt.

The modifier can be added into asphalt in a large amount to obtain high-viscosity rubber asphalt with the performance index reaching the standard, and in order to further improve the performance of the high-viscosity rubber asphalt, in a preferred embodiment, the high-viscosity rubber asphalt also comprises an elastomer polymer. Of course, as mentioned above, due to the special structure of the combination body formed by the linear active rubber and the olefin polymer in the modifier, the modifier can be added in a large proportion on the basis of maintaining the performance of the modified asphalt, and the addition amount of the corresponding elastomer polymer can be obviously reduced, thereby effectively reducing the material cost. In a preferred embodiment, the high viscosity rubber asphalt comprises 100 parts of asphalt, 25-50 parts of modifier, 0.2-2 parts of first crosslinking assistant and 0-3 parts of elastomer polymer.

The elastomeric polymer may be selected from those commonly used in the art, and preferably one or more of SBS, SEBS, SIS, SBR, EVA and POE are used.

In the high-performance rubber asphalt mixture, the dosage ratio between the high-viscosity rubber asphalt and the aggregate is the conventional ratio in the asphalt pavement materials in the field, and can be adaptively adjusted according to the type of the aggregate and the grade of the pavement. The type of aggregate may also be of a type commonly used in the art and will not be described in further detail herein.

According to another aspect of the present invention, there is also provided a preparation method of the above high-performance rubber asphalt mixture, which comprises the following steps: banburying and mixing the linear active rubber, the olefin polymer and the second crosslinking assistant to obtain a premix; carrying out extrusion molding and grain cutting on the premix to obtain a modifier; mixing the modifier, the asphalt and the first crosslinking assistant to obtain high-viscosity rubber asphalt; and mixing the high-viscosity rubber asphalt with the aggregate to obtain the high-performance rubber asphalt mixture. The high-performance rubber asphalt mixture material prepared by the method has effectively reduced cost, wherein the adopted high-viscosity rubber asphalt has higher dynamic viscosity at 60 ℃ and higher toughness/toughness, the high-temperature viscosity is still less than or equal to 3pa.s, and other physical and chemical properties meet the index requirements of JT/T860.2-2013, so that the rubber asphalt mixture also has higher comprehensive performance correspondingly, and is very suitable for being applied to high-grade asphalt pavement materials.

In a preferred embodiment, the petroleum resin is added simultaneously during the internal mixing process. In order to fully mix the components and form a stable structure, preferably, the mixing temperature in the banburying mixing process is 80-140 ℃, and the mixing time is 10-30 min; preferably, the extrusion temperature in the extrusion molding process is 130-220 ℃, and the extrusion speed is 20-100 rpm.

In a preferred embodiment the linearized active rubber is prepared by one of the following methods:

The linearized active rubber is prepared in the manner described above, with the beneficial effects as described previously.

In order to further improve the properties of the high-viscosity rubberized asphalt and of the rubberized asphalt mix, in a preferred embodiment, the elastomeric polymer is added simultaneously with the step of mixing the modifier, the asphalt and the first crosslinking aid.

The specific mixing process may be adjusted, and preferably, the step of mixing the modifier, the asphalt, the first crosslinking aid, and the elastomeric polymer comprises: heating asphalt to 170-190 ℃, then mixing the asphalt with an elastomer polymer, and stirring for 30-60 min under the condition of heat preservation to obtain a mixture A; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm; mixing the mixture A with a modifier, and stirring for 60-120 min under the condition of heat preservation to obtain a mixture B; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm; carrying out circulating shearing and grinding on the mixture B to obtain a mixture C; preferably, the grinding temperature in the step is 170-190 ℃, and the grinding rotating speed is 5000-10000 rpm; mixing the mixture C with a first crosslinking auxiliary agent, and stirring for 30-60 min under the condition of heat preservation to obtain high-viscosity rubber asphalt; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm.

The above-mentioned step of mixing the high-viscosity rubber asphalt with the aggregate can be carried out in a manner commonly used in the art and will not be described herein.

According to another aspect of the invention, the application of the high-performance rubber asphalt mixture as an asphalt pavement material is also provided. As mentioned above, the high-performance rubber asphalt mixture provided by the invention has the beneficial effects of low material cost and excellent performance, and can effectively reduce the pavement laying cost when used as an asphalt pavement material, and meanwhile, the pavement has good comprehensive performance.

Specifically, the high-performance rubber asphalt mixture provided by the invention can be used in typical high-grade asphalt pavement materials, such as AC type continuous dense-graded asphalt mixture, SMA type asphalt mastic structure asphalt mixture, OGFC type open-graded drainage asphalt mixture and the like.

The beneficial effects of the present invention are further illustrated by the following examples:

preparation of linearized active rubber:

examples 1 to 17

In these examples, the following processes were used to conduct the devulcanization regeneration of the waste rubber:

step 1: putting 80-mesh waste tire rubber powder and a photocatalyst into a high-speed stirring and mixing unit, stirring at the stirring speed of 1000rpm for 20min to 70 ℃, stopping stirring, putting the materials into a cooling unit, cooling and discharging to obtain a mixture;

step 2: putting the mixture into a supercritical carbon dioxide reaction kettle, injecting carbon dioxide gas into the reaction kettle by using a high-pressure pump to adjust the pressure in the reaction kettle, and simultaneously heating to convert the carbon dioxide gas into a supercritical state; starting stirring to swell the mixture in supercritical carbon dioxide to obtain a swollen mixture;

and step 3: maintaining the supercritical carbon dioxide environment, starting a built-in ultraviolet light source to perform ultraviolet irradiation on the swelling mixture, and irradiating for a certain time;

and 4, step 4: and (5) releasing pressure and recovering carbon dioxide gas, stopping illumination and cooling, and taking out a target product and testing.

Examples 1 to 17 differ in the following parameters: the type and amount of the photocatalyst (weight percentage of the waste rubber powder), the temperature of the supercritical carbon dioxide system (same swelling temperature and desulfurization reaction temperature), the pressure (same swelling pressure and desulfurization reaction pressure), the swelling time, the ultraviolet light irradiation time and the ultraviolet light wavelength are shown in table 2:

TABLE 2

Example 18

The process flow in this example is the same as in example 9, except that:

step 1: and (3) putting 120-mesh waste tire rubber powder and a photocatalyst into a high-speed stirring and mixing unit, stirring at the stirring speed of 700rpm for 30min to 60 ℃, stopping stirring, putting the materials into a cooling unit, cooling and discharging to obtain a mixture.

Example 19

The process flow in this example is the same as in example 10, except that:

step 1: and (3) putting the 120-mesh waste sole rubber powder and the photocatalyst into a high-speed stirring and mixing unit, stirring at the stirring speed of 1500rpm for 30min to 85 ℃, stopping stirring, putting the materials into a cooling unit, cooling and discharging to obtain a mixture.

Example 20

The process flow in this example is the same as in example 10, except that:

step 1: and (3) putting the 80-mesh waste conveyor belt rubber powder and the photocatalyst into a high-speed stirring and mixing unit, stirring at the stirring speed of 600rpm for 10min to 40 ℃, stopping stirring, putting the materials into a cooling unit, cooling and discharging to obtain a mixture.

Example 21

100 parts of waste tire tread rubber powder with the particle size of 1mm is adopted, 6 parts of pine tar, 4 parts of naphthenic oil, 0.5 part of phenyl mercaptan and 0.5 part of n-butylamine are added as regenerants, and the mixture is mixed and stirred for 10min at the temperature of 100 ℃ in a stirrer and then is placed for 36h at the temperature of 50 ℃. It was then fed into a co-rotating twin-screw extruder (D30 mm, L/D52/1, six heating zones) via a feeding device: screw rotation speed 150rpm, 6 temperature zones: changing the internal thread composition of the screw at 120 ℃, 180 ℃, 230 ℃, 280 ℃, 150 ℃ and 100 ℃, and adding a right-handed thread element to ensure that the maximum pressure reaches 7.5 MPa. And (3) after reacting for 5min, extruding by a screw extruder die to obtain the reclaimed rubber.

Example 22

100kg of 30-mesh vulcanized rubber powder was put into a vertical depolymerizer, and 70kg of paraffin oil, 22kg of solid coumarone resin, 3kg of phthalic anhydride, 4.5kg of formalin and 0.5kg of resorcinol were sequentially added. And sealing the material port, stirring, heating to 180 ℃, controlling the pressure at 0.5MPa, reacting for 2.5 hours, cooling, discharging residual gas, discharging, and filtering by using a 100-mesh metal sieve to obtain the reclaimed rubber.

Comparative example 1

100 parts of waste tire rubber powder and 10 parts of nano cadmium sulfide are stirred and mixed uniformly by a high-speed plasticizing reaction unit. The rotating speed of the reaction unit is firstly adjusted to 1200rpm, when the temperature reaches 90 ℃, stirring is stopped, the materials are put into a cooling unit, the rotating speed is 50rpm, and when the temperature is about 30 ℃, discharging is carried out. Placing the stirred material into a stirrer, and irradiating the material with ultraviolet lamp for 30 min. The UV lamp used was a 3kw high pressure mercury lamp with UV wavelength of 365 nm.

The main machine rotating speed of the double-screw extruder is adjusted to be 220rpm, the feeding rotating speed is adjusted to be 15rpm, and the temperatures of 7 temperature zones of the double screws are as follows: 54-67-77-76-79-73-42 ℃, the temperature of each area is not higher than 100 ℃, the production state at normal temperature and normal pressure is realized, and the discharge detection is carried out.

Comparative example 2

The process flow in this comparative example is the same as in example 10, except that the system temperature: 30 ℃, pressure 7MPa, critical parameters of CO 2: 31.26 deg.C and 7.29MPa, carbon dioxide is in non-supercritical state.

The devulcanization effect characterization was performed on the devulcanized reclaimed rubbers prepared in examples 1 to 22, comparative examples 1 and 2(D1 and D2), and the characterization results are shown in table 3, and the characterization methods are as follows:

the following treatments were carried out on each of the above products:

firstly, acetone is used as a solvent, and a Soxhlet extraction method is adopted to continuously extract for 48 hours until small molecules (acetone soluble substances) are completely extracted and separated by the acetone. Subsequently, the soluble fraction was dried in a vacuum drying oven until the mass was unchanged, the insoluble fraction was dried until the mass was unchanged, and secondary extraction was continued using toluene as a solvent to separate a macromolecular soluble substance (toluene soluble substance) and a crosslinked insoluble substance (gel).

The average molecular weights of the acetone soluble substance and the toluene soluble substance and the polymer polydispersity number PDI are respectively tested (GPC test can be simultaneously characterized, and the molecular weights and the polydispersity numbers PDI are respectively tested) by the following methods: acetone-soluble and toluene-soluble substances were sufficiently swollen with toluene, and the number average molecular weight (M) of the sample was measured by using a GPC analyzer model 515-_n) And calculating the polydispersity index (PDI) by taking tetrahydrofuran as a mobile phase and polystyrene as a standard sample, and measuring the temperature at 35 ℃.

The crosslink density of the gel was measured as follows: the crosslinking density test employs an equilibrium swelling method. The weighed sample was placed in a ground conical flask with a stopper containing 150ml of a good solvent (toluene was used as a good solvent in this experiment), immersed in a constant temperature water bath, kept at 30 ℃ for 72 hours, taken out after equilibration, weighed with an analytical balance, and dried in a vacuum desiccator at 50 ℃ for 4 hours. When the sample swells to equilibrium in a suitable solvent, the solvent molecules enter the crosslinked network at the same rate as they are expelled. And obtaining a crosslinking density formula, namely a Flory-Rehner formula, according to the basis of the rubber elasticity statistical theory.

TABLE 3

The gel content, the sol content, the average molecular weight of the sol, the sol PDI and the gel crosslinking density are the most visual and accurate means for representing the degradation degree of the crosslinked rubber. Higher sol content, lower gel crosslink density, indicate higher rubber degradation. The higher the toluene solubles content and the higher the molecular weight at the same sol content, the higher the content of linearized macromolecules in the reclaimed rubber after decrosslinking. The weight percentage of the linearized molecule is the sol content/(sol content + gel content); the weight percentage of the gradient small molecules in the linearized molecule is acetone soluble content/(acetone soluble + toluene soluble content).

1. From the comparison of the data in the above examples and comparative example 2, it can be seen that: in the supercritical carbon dioxide fluid state, the same process means is adopted, and the desulfurization and degradation degree of the waste rubber is far higher than that in the non-supercritical state (the carbon dioxide critical point is 38 ℃ and 7.38 MPa). This is due to: in the supercritical state, the carbon dioxide fluid can fully exert the excellent dissolving and extracting performances of the rubber powder, and can fully dissolve linear macromolecules and micromolecules, the macromolecules firstly desulfurized and degraded on the surface of the waste rubber powder are disentangled through the swelling effect of the supercritical carbon dioxide fluid, and are peeled from the crosslinked rubber powder body and dissolved in the fluid. And then, under the action of illumination and a catalyst, the inner layer of the crosslinked rubber powder is continuously desulfurized and degraded and has the same action as the surface layer until the whole crosslinked waste rubber powder is desulfurized and degraded. The linearized active rubber is in a pasty and semi-fluid state at normal temperature. However, in a non-supercritical state, the surface of the waste rubber powder is subjected to desulfurization degradation under the action of illumination and a catalyst, and the surface layer subjected to desulfurization degradation still wraps the surface of the rubber powder due to the absence of the action of an external solvent, so that the rubber of the desulfurized surface layer blocks the penetration of ultraviolet light, namely, the illumination cannot reach the inside of the waste rubber powder, and the inside of the waste rubber powder still is in a three-dimensional cross-linked state. Therefore, even if photocatalytic degradation is carried out in a non-supercritical carbon dioxide state, the degradation efficiency and degree are low, sufficient desulfurization degradation of the crosslinked waste rubber component cannot be realized, and the basically fully uncrosslinked linearized rubber cannot be prepared;

2. as can be seen from the comparison of the data in the above examples and comparative examples 1 and 2, the method of the present invention provides a higher degree of desulfurization of the waste rubber crumb and a higher degree of linearization of the devulcanized rubber. In particular, the twin-screw mechanical devulcanization used in example 21 was carried out without differential chain scission of the three-dimensional crosslinked network in the waste rubber powder, and therefore, the gel content was relatively low, but at the same time, the small molecules content was high, the large molecules content was low, and the molecular weight of the large molecular chains was relatively low. The preparation methods adopted in examples 1 to 20 have the advantage of selective chain scission for S-S bonds and S-C bonds in the three-dimensional cross-linked network of the waste rubber powder, so that the desulfurization linearized active rubbers prepared in examples 1 to 20 of the present invention have higher macromolecular content than that of example 21. In example 22, the rubber powder is degraded by a high-temperature boiling method, and although the degree of degradation of the rubber powder is high, the content of gradient small components in the linearized active rubber is high and the content of linearized macromolecules is low because a large amount of small-molecule softeners (paraffin oil and solid coumarone) are added in the preparation method.

3. More particularly, as can be seen from the comparison of the data in examples 1 to 17 above, the use of the composite inorganic photocatalyst to optimize the processes in the swelling treatment step and the photocatalytic desulfurization reaction step can significantly improve the desulfurization regeneration degree of the waste rubber powder, resulting in a substantially fully uncrosslinked, linearized rubber. And the process is optimized, and the prepared fully-desulfurized de-crosslinked linearized rubber has high macromolecular polymer (rubber) content, large molecular weight and narrow macromolecular chain distribution coefficient (polydispersity index PDI).

4. When photocatalytic degradation is performed under supercritical carbon dioxide, the requirements on the wavelength of ultraviolet light are not strict, and the photocatalytic degradation can be realized within the wavelength range of 350-420.

Preparation of the modifier:

examples 23 to 44, comparative examples 3 and 4(D3 and D4)

Examples 23 to 44, comparative examples 3 and 4(D3 and D4) high tack rubber asphalt modifiers were prepared as follows:

raw materials:

linearized active or reclaimed rubber: examples 23 to 44, comparative examples 3 and 4(D3 and D4) used the linearized active rubber or reclaimed rubber prepared in examples 1 to 22, comparative examples 1 and 2(D1 and D2), respectively, in the order listed in table 4;

polyethylene wax: is prepared by degrading waste plastics, the process refers to Chinese patent CN101885857A, and the molecular weight of the polyethylene wax is 90-125 ℃ of melting point.

Crosslinking assistant agent: DCP and maleic anhydride in a weight ratio of 1: 1;

petroleum resin: c5 petroleum resin and C9 petroleum resin in a weight ratio of 1: 1.

The weight ratios between the above four raw materials are shown in Table 4.

The preparation process comprises the following steps:

(1) injecting the raw materials into an internal mixing device for internal mixing to obtain a premix; wherein the mixing temperature is as follows: 120 ℃, mixing time: 20 min;

(2) injecting the premix into an extrusion device through a feeding device, and carrying out secondary mixing extrusion molding at the extrusion temperature: 200 ℃, extrusion rate: 60rpm

(3) And cutting the extruded mixture into particles by a particle cutting device, cutting the particles at a rotating speed of 40Hz, and packaging to obtain the modifier.

Examples 45 to 49

The starting materials and preparation were as in example 25 (linearized active rubber from example 3). The difference lies in that the dosage proportions of the raw materials are different, and the specific dosage proportions are shown in table 4:

TABLE 4

Example 50

The raw materials and process used were the same as in example 25, except that polyethylene wax was replaced with oxidized polyethylene wax having a molecular weight of 3000-7000 and a melting point of 90-125 ℃.

Example 51

The raw materials and process used were the same as in example 25, except that the polyethylene wax was replaced with sasobit wax having a molecular weight of 3000-7000 and a melting point of 90-125 ℃.

Example 52

The raw materials and process used were the same as in example 25, except that the polyethylene wax was replaced with a polyamide wax having a molecular weight of 3000-7000 and a melting point of 90-125 ℃.

Preparation of high-viscosity rubber asphalt

Examples 53 to 85 and comparative examples 5 and 6

The process for producing high-viscosity rubber asphalt using the modifiers prepared in examples 23 to 52 and comparative examples 3 and 4 was as follows, except for the kinds of raw materials or the amounts of the components, as shown in Table 5.

The process comprises the following steps:

heating asphalt (Qinhuang island 70A) to 190 ℃, then mixing with an elastomer polymer (SBS), and stirring for 60min at the constant temperature to obtain a mixture A; the heat preservation temperature in the step is 190 ℃, and the stirring speed is 1000 rpm;

mixing the mixture A with a modifier, and stirring for 60min under the condition of heat preservation to obtain a mixture B; the heat preservation temperature in the step is 190 ℃, and the stirring speed is 1000 rpm;

carrying out circulating shearing and grinding on the mixture B to obtain a mixture C; the grinding temperature in the step is 190 ℃, and the grinding rotating speed is 10000 rpm;

mixing the mixture C with a first crosslinking aid (sulfur), and stirring for 30-60 min under the condition of heat preservation to obtain high-viscosity rubber asphalt; the holding temperature in this step was 190 ℃ and the stirring rate was 1000 rpm.

TABLE 5

Examples 86 to 90

The preparation process and raw materials are the same as in example 55, except that the dosage and the mixture ratio of the raw materials are different, and the details are shown in table 5:

TABLE 5

Example 91

The preparation process, raw materials and formulation were the same as in example 55, except that the elastomeric polymer in example 55 was replaced with SBR and sulfur was replaced with prom.

Example 92

The preparation process, raw materials and mixture ratio were the same as those in example 55, except that the elastomer polymer in example 55 was replaced with SEBS, and sulfur was replaced with zinc oxide.

Example 93

The preparation process, raw materials and proportions are the same as in example 55, except that the elastomeric polymer in example 55 is replaced by EVA/POE (weight ratio of 1:1), and sulfur is replaced by TMTD/pro-D (weight ratio of 1: 1).

And (4) result characterization:

the high-viscosity rubber asphalt prepared in the above examples and comparative examples was subjected to the following property characterization: test methods and standards: JTG E20-2011 test protocol for road engineering asphalt and asphalt mixtures.

The characterization results are shown in Table 6:

TABLE 6

From the above data, it can be seen that:

1: in the aspect of reflecting the important indexes of high-viscosity modified asphalt, namely 60 ℃ dynamic viscosity/25 ℃ viscosity toughness/25 ℃, the cross-linked rubber is treated by the technology, so that the linearization degree is high, the property of the rubber can be reflected better, meanwhile, a part of olefin polymer is compounded and prepared into a modifier, the modifier is linearized (or micro-crosslinked) in the asphalt, macromolecular chains are fully entangled to form a network structure, the cohesion of the modified asphalt is fully improved (the average molecular weight of the modified asphalt is simultaneously improved), and the 60 ℃ dynamic viscosity of the modified asphalt and the toughness and the viscosity toughness of the modified asphalt can be greatly improved; in addition, under the action of a proper amount of olefin polymer (the melting point is higher than 60 ℃), the cohesive force and the dynamic viscosity of the modified asphalt are further improved; the untreated (or untreated) rubber powder of the comparative example cannot fully exert the macromolecular winding property of rubber because the molecular chain structure of the rubber powder is in a cross-linked state, so that the dynamic viscosity, toughness and viscotoughness of the modified asphalt at 60 ℃ cannot be fully improved, and in addition, the untreated (micro-treated) rubber powder has a plurality of stress concentration points in the modified asphalt, so that the cohesive force of the modified asphalt is negatively influenced;

2: the viscosity at 135 ℃ reflects the production construction workability of the modified asphalt, and the high-temperature viscosity of the modified asphalt is not greatly improved due to the large proportion of rubber, because the reticular structure of the cross-linked rubber is basically destroyed after the cross-linked rubber is treated by the technology, the capability of absorbing light components of the asphalt to swell is greatly weakened, and the influence on the high-temperature viscosity of the modified asphalt is limited; the cross-linked rubber of the comparative example is not treated (untreated), and when the cross-linked rubber is added in the same proportion, the high-temperature viscosity of the cross-linked rubber is greatly improved, so that the production, construction and workability of the modified asphalt are adversely affected;

3: the cross-linked rubber has high linearization degree after being processed, is uniformly and linearly distributed in a modified asphalt system, and simultaneously generates micro cross-linking with asphalt and the cross-linking agent under the action of the cross-linking auxiliary agent to form a stable net structure which has good stability and strong resistance to external force damage, and reflects the low-temperature ductility (5 ℃) of the modified asphalt to be greatly improved; compared with untreated rubber, the stress concentration point of the untreated rubber is greatly increased, and meanwhile, the low-temperature flexibility of the linearized rubber cannot be exerted, so that the low-temperature stretchability of the modified asphalt cannot be obviously improved;

4: in the aspect of reflecting the high-temperature performance (softening point) of the modified asphalt, the cross-linked rubber has high linearization degree after being processed, is uniformly and linearly distributed in a modified asphalt system, and simultaneously generates micro cross-linking with the asphalt and the cross-linked rubber under the good heat-resistant action of a cross-linking auxiliary agent and an olefin polymer to form a stable mesh structure, and the mesh structure has good stability and strong capability of resisting external force damage, so that the high-temperature resistance (softening point) of the modified asphalt is improved; the untreated rubber of the comparative example has greatly increased stress concentration points, so that the high temperature resistance (softening point) of the modified asphalt cannot be obviously improved;

5: on the aspect of reflecting the aging resistance of the high-viscosity modified asphalt, as the rubber of the technology is subjected to deep activation treatment, the macromolecular chain of the rubber is linearized, and simultaneously, carbon black and part of physical/chemical anti-aging agents are in a free state, the anti-aging agents carried by the rubber can greatly improve the aging resistance of the modified asphalt, while the anti-aging agents of the rubber are still in a combined glue state with the rubber and cannot be fully dissociated in a modified asphalt system in an untreated (micro-treated) cross-linked rubber, the contribution to the heat resistance and aging resistance of the modified asphalt is insufficient;

6: in the selection of the additional polymer of the high-viscosity modified asphalt, the unsaturated double bond content of the SEBS molecular chain is lower than that of SBS, so that the high-temperature and aging-resistant effects of the modified asphalt are more excellent; the addition amounts of the modifier and the polymer are too high, so that the viscosity of the system is obviously influenced, the addition amounts of the modifier and the additional polymer are optimized in the technical scheme, and the material cost of the high-viscosity rubber asphalt can be fully reduced;

7: the addition of the petroleum resin in the present technology has good self-adhesion property and contributes well to the adhesion property (toughness/toughness) of the modified asphalt, and the low molecular weight thereof does not substantially affect the high-temperature viscosity of the modified asphalt.

Preparation of high-performance rubber asphalt mixture

Different rubber asphalt mixtures are prepared by using the high-viscosity rubber asphalt and the aggregate prepared in the previous examples or comparative examples as raw materials.

Application of high-viscosity rubber asphalt in AC type continuous dense-graded asphalt mixture (AC-13)

Aggregate type:

the above aggregate was mixed with the high-viscosity rubber asphalt prepared in examples 55, 74, 78, 89, 90, D5, D6 in the oil-stone ratio in table 7 to prepare an asphalt mixture.

Application of high-viscosity rubber asphalt in SMA type asphalt mastic structure asphalt mixture

Aggregate type:

the above aggregate was mixed with the high-viscosity rubber asphalt prepared in examples 55, 74, 78, 89, 90, D5, D6 in the oil-stone ratio in table 8 to prepare an asphalt mixture.

Application of high-viscosity rubber asphalt in OGFC (one glass cement mixing fiber) type open-graded drainage asphalt mixture

Aggregate type:

the above aggregate was mixed with the high-viscosity rubber asphalt prepared in examples 55, 74, 78, 89, 90, D5, D6 in the oil-stone ratio in table 9 to prepare an asphalt mixture.

The preparation process and the method of the asphalt mixture are carried out according to JTG F40-2004 highway asphalt pavement construction technical specifications and a detection method according to JTG E20-2011 highway engineering asphalt and asphalt mixture test procedures, and the results are as follows:

AC-13: Table 7

SMA-13: Table 8

OGFC-13 TABLE 9

From the properties of the asphalt mixture of the above embodiment, it can be seen that:

the high-viscosity rubber asphalt prepared by the technical scheme is applied to conventional AC-13 and SMA-13 asphalt mixtures, and has better high-temperature rutting resistance (dynamic viscosity at 60 ℃) because the modified asphalt has better dynamic viscosity at 60 ℃, higher cohesion of the asphalt and stronger bonding performance and deformation resistance after being mixed with aggregates; the high-viscosity rubber asphalt of the technical scheme has more excellent 25 ℃ viscotoughness/toughness, so the performance is more excellent by reflecting the water damage resistance (soaking Marshall/freeze-thaw splitting strength ratio) of the asphalt mixture; meanwhile, the two advantages of the technical scheme lead the anti-segregation effect and the road surface loosening effect of the asphalt mixture (SMA-13) to be more excellent; in addition, due to the uniqueness of the technical scheme, the high-temperature brookfield viscosity of the high-viscosity rubber asphalt is moderate, so that the high-temperature brookfield viscosity is reflected on the final application of asphalt, namely asphalt mixture, and has moderate oilstone ratio, which means that the cost performance is higher, and in a comparison case, because the high-temperature viscosity is very high, the high-temperature brookfield viscosity is not easy to disperse when being mixed with aggregate, so that more oil is needed, namely the cost performance is lower;

on the open graded drainage pavement (OGFC-13) which reflects the special application of the high-viscosity rubber asphalt, the technical scheme has more excellent dynamic viscosity at 60 ℃ and 25 ℃ viscotoughness/toughness, so that the high-temperature rutting resistance is more excellent; meanwhile, due to the larger cohesive force of the high-viscosity rubber asphalt in the technical scheme, the wrapping and bonding capability of the high-viscosity rubber asphalt and the aggregate is stronger, so that the performance of the high-viscosity rubber asphalt is reflected on the performance (flying loss/leakage loss) of the mixture, and the performance is better. In addition, due to the uniqueness of the technical scheme, the high-temperature brookfield viscosity of the high-viscosity rubber asphalt is moderate, so that the high-temperature brookfield viscosity is reflected on the final application of asphalt, namely asphalt mixture, and has a moderate oilstone ratio, which means that the cost performance is higher, and in a comparative case, because the high-temperature viscosity is very high, the high-temperature brookfield viscosity is not easy to disperse when being mixed with aggregate, so that more oil is needed, namely the cost performance is lower.

The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The high-performance rubber asphalt mixture comprises high-viscosity rubber asphalt and aggregate and is characterized in that the high-viscosity rubber asphalt comprises asphalt, a modifier and a first crosslinking aid, the modifier comprises raw materials of linearized active rubber, an olefin polymer with the molecular weight of 3000-7000 and the melting point of 90-125 ℃ and a second crosslinking aid, the linearized active rubber is obtained by desulfurization treatment of waste rubber powder, and the weight percentage content of linearized molecules in the linearized active rubber is more than or equal to 75%.

2. The high-performance rubber asphalt mixture according to claim 1, wherein the linearized active rubber is prepared by one of the following methods:

placing the mixture of the waste rubber powder and a photocatalyst in supercritical carbon dioxide under ultraviolet light for photocatalytic desulfurization reaction to obtain the linearized active rubber; preferably, the photocatalyst is a composite inorganic photocatalyst; more preferably, the photocatalyst is selected from Co-doped TiO₂、ZrO₂/ZnO composite and ZrO₂/TiO₂One or more of the complexes; further preferably, the amount of the photocatalyst is 0.5-3% of the weight of the waste rubber powder;

secondly, pretreating the waste rubber powder and a regenerant at the temperature of 60-150 ℃ for 10-30 min, and standing at the temperature of 50-120 ℃ for 6-36 h to obtain a pretreated product; extruding the pretreated product in a screw extruder, wherein the extrusion temperature is 100-480 ℃, the extrusion pressure is 3-15 Mpa, and the reaction time is 1-15 min, so as to obtain the linearized active rubber; preferably, the regenerant comprises a softener selected from one or more of coal tar, pine tar, tall oil, naphthenic oil, dipentene, paraffinic oil, oleic acid, and rosin, and an activator selected from one or more of aromatic disulfide, polyalkylphenol sulfide, phenyl mercaptan, and n-butylamine; preferably, the weight ratio of the waste rubber powder, the softening agent and the activating agent is 100: (5-30): (0.5 to 5);

thirdly, placing the waste rubber powder into a vertical depolymerizer, adding a solvent, a desulfurization catalyst and a cocatalyst, and then performing desulfurization reaction at the temperature of 160-180 ℃ and under the pressure of 0.5-0.7 MPa to obtain the linearized active rubber; wherein the solvent is paraffin oil and/or solid coumarone, the desulfurization catalyst is phthalic anhydride, and the cocatalyst is formalin and/or resorcinol.

3. The high-performance rubber asphalt mixture according to claim 1 or 2, wherein the weight percentage of the linearized macromolecules with the molecular weight of 20000-70000 in the linearized active rubber is more than or equal to 80%.

4. The high performance rubber asphalt mixture according to any one of claims 1 to 3, wherein the olefin polymer is one or more of polyethylene wax, oxidized polyethylene wax, sasobit wax and polyamide wax; preferably said olefin polymer is said polyethylene wax; further preferably, the polyethylene wax is made by degrading waste plastics.

5. The high-performance rubber asphalt mixture according to any one of claims 1 to 3, wherein the raw material of the modifier further comprises a petroleum resin, preferably the petroleum resin is one or more of a C5 petroleum resin, a C9 petroleum resin, a phenolic resin and a terpene resin, and more preferably, the raw material of the modifier comprises 55 to 85 parts by weight of the linearized active rubber, 10 to 30 parts by weight of the olefin polymer, 0.3 to 2 parts by weight of the second crosslinking assistant and 5 to 15 parts by weight of the petroleum resin.

6. The high-performance rubber asphalt mixture according to claim 1,

the first crosslinking auxiliary agent is one or more of sulfur, M, TMTD, D, zinc oxide and stearic acid;

preferably, the second crosslinking assistant is one or more of n-butyl-4, 4-di (tert-butylperoxy) valerate, dicumyl peroxide, maleic anhydride and phthalic anhydride;

7. The high performance rubber asphalt mixture according to any one of claims 1 to 6, wherein said high viscosity rubber asphalt further comprises an elastomeric polymer; preferably, the elastomeric polymer is one or more of SBS, SEBS, SIS, SBR, EVA, and POE.

8. The high-performance rubber asphalt mixture according to claim 7, wherein the high-viscosity rubber asphalt comprises 100 parts by weight of the asphalt, 25 to 50 parts by weight of the modifier, 0.2 to 2 parts by weight of the first crosslinking assistant, and 0 to 3 parts by weight of the elastomeric polymer.

9. A method for preparing a high-performance rubber asphalt mixture according to any one of claims 1 to 8, wherein the method comprises the following steps:

banburying and mixing the linear active rubber, the olefin polymer and the second crosslinking assistant to obtain a premix;

carrying out extrusion molding and grain cutting on the premix to obtain the modifier;

mixing the modifier, the asphalt and the first crosslinking assistant to obtain high-viscosity rubber asphalt; and

and mixing the high-viscosity rubber asphalt with aggregate to obtain the high-performance rubber asphalt mixture.

10. The method according to claim 9, wherein during the banburying mixing, petroleum resin is added simultaneously; preferably, the mixing temperature in the banburying mixing process is 80-140 ℃, and the mixing time is 10-30 min; preferably, the extrusion temperature in the extrusion molding process is 130-220 ℃, and the extrusion speed is 20-100 rpm.

11. The method according to any one of claims 9 to 10, wherein an elastomeric polymer is added simultaneously in the step of mixing the modifier, the asphalt and the first crosslinking assistant.

12. The method of claim 11, wherein the step of mixing the modifier, the asphalt, the first crosslinking co-agent, and the elastomeric polymer comprises:

heating the asphalt to 170-190 ℃, mixing the asphalt with the elastomer polymer, and stirring for 30-60 min under the condition of heat preservation to obtain a mixture A; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm;

mixing the mixture A and the modifier, and stirring for 60-120 min under the condition of heat preservation to obtain a mixture B; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm;

carrying out circulating shearing and grinding on the mixture B to obtain a mixture C; preferably, the grinding temperature in the step is 170-190 ℃, and the grinding rotating speed is 5000-10000 rpm;

mixing the mixture C with the first crosslinking aid, and stirring for 30-60 min under the condition of heat preservation to obtain the high-viscosity rubber asphalt; preferably, the heat preservation temperature in the step is 170-190 ℃, and the stirring speed is 500-1000 rpm.

13. Use of the high-performance rubber asphalt mixture according to any one of claims 1 to 8 as an asphalt pavement material.

14. Use according to claim 13, characterized in that the high-performance rubber asphalt mixture is used as continuous close-graded asphalt mixture of AC type, asphalt mastic structure asphalt mixture of SMA type and open-graded drainage asphalt mixture of OGFC type.