CN114058097A - High-performance uncrosslinked rubber asphalt and preparation method thereof - Google Patents

Abstract

The invention relates to a high-performance uncrosslinked rubber asphalt and a preparation method thereof, wherein a polyolefin modifier and an SBS modifier (styrene-butadiene block polymer) are doped as a separating agent of uncrosslinked rubber during deep decrosslinking of rubber powder, so that the viscosity of the uncrosslinked rubber can be reduced, the cohesion of the uncrosslinked rubber can be prevented, the polyolefin modifier can be rapidly melted at high temperature, rubber particles can be rapidly opened, and the dispersibility of rubber particles can be remarkably enhanced. And simultaneously, the polyolefin and SBS modifier can obviously improve the performance of the asphalt. The invention deeply degrades the uncrosslinked rubber, improves the cohesive force of the rubber asphalt, reduces the Brookfield viscosity of the rubber asphalt, improves the construction performance and achieves higher rubber mixing amount.

Description

High-performance uncrosslinked rubber asphalt and preparation method thereof

Technical Field

The invention relates to the field of asphalt, in particular to high-performance uncrosslinked rubber asphalt and a preparation method thereof.

Background

With the development of the automobile industry and the improvement of the living standard of people, the automobile holding capacity is rapidly increased, the yield of waste tires is increased at a speed of 8% -10% per year, the resource utilization is urgently needed, and the processing of the waste tires into rubber powder to be applied to the modification of asphalt becomes an important way for the resource utilization of the waste tires. The waste tire rubber powder is used for paving asphalt pavements, and is a technology for practicing green traffic. The waste tires contain various high molecular polymers such as natural rubber, Styrene Butadiene Rubber (SBR) and the like, and additives such as an anti-aging agent and the like, and are effective components for improving the performance of asphalt.

At present, the rubber asphalt is prepared by adopting a traditional mcdona wet process, namely, waste tires are simply crushed into rubber powder, the rubber powder is added into asphalt, and the rubber powder is stirred and developed to prepare the rubber asphalt to be applied to asphalt pavements. Because the tire is molded by a vulcanization process in the processing and production process, a plurality of rubbers are used together, and the reinforcing is carried out by fillers such as carbon black, and finally a stable and multi-level three-dimensional cross-linked structure is formed. The rubber powder is only slightly depolymerized on the surface of the asphalt and mainly plays a role of a core in the asphalt, and the rubber asphalt does not form a uniform colloid and is very unstable. On one hand, the rubber powder is continuously degraded in the asphalt in the storage process, and the performance index of the asphalt is unstable; on the other hand, the rubber powder is likely to precipitate from the asphalt during storage, and segregation occurs. Therefore, the rubber powder needs to be pretreated, so that the rubber powder is subjected to crosslinking decomposition under the action of chemistry, machinery and the like, the three-dimensional network structure of the waste rubber powder is opened, effective rubber components and carbon black are separated out to play a role in asphalt, and meanwhile, the rubber powder is fully dissolved in the asphalt, so that the asphalt forms uniform colloid, and the storage stability of the asphalt is obviously enhanced.

CN102501335A discloses a new process for continuous reduction and regeneration of waste rubber, which is carried out according to the following steps: (1) high-speed plasticizing: putting the waste rubber powder, the rubber regenerant and the softening oil into a stirring tank of a high-speed plasticizing reaction unit for mixing; (2) mechanical chemical reaction: shearing and rolling the rubber powder into strips and particles through a mechanochemical reactor; (3) reduction of the rubber screw: the S-S cross-linking bond of the vulcanized rubber can be cut off in a short time under the high-shear screw combination, the C-C bond is rarely damaged, and the higher physical property of the rubber is kept; (4) screw kneading: secondary shearing and cooling are carried out; (5) refining: and extruding the sheet by an open mill to obtain the reclaimed rubber. The scheme does not mention the application of the prepared waste rubber to rubber asphalt and does not relate to the mixing condition of rubber powder in the asphalt.

CN102977404A discloses a method for realizing rapid desulfurization regeneration of waste rubber by using two twin-screw extruders connected in series, adding waste rubber powder which is fully permeated and swelled by a regenerant after being pretreated into a first counter-rotating twin-screw extruder, and selectively breaking cross-linking bonds under the action of temperature in the extruder by using the advantages of strong conveying capacity and weak shearing of the first counter-rotating twin-screw extruder, thereby replacing the traditional high-temperature high-pressure dynamic reaction tank; the obtained desulfurized rubber powder is cooled by a conveying device and then is butted into a second co-rotating double-screw extruder, the advantage of strong shearing force is utilized, the high shearing action is exerted at low temperature, so that a refiner is replaced, and finally, the regenerated rubber is obtained by extrusion through a machine head. The whole preparation process is completed under the condition of closed oxygen insulation, and the obtained reclaimed rubber has excellent performance. The scheme does not mention the application of the prepared waste rubber to rubber asphalt and does not relate to the mixing condition of rubber powder in the asphalt.

EP3611221B1 discloses a process for the continuous preparation of reclaimed rubber using a multistage screw extruder comprising: firstly, mixing waste rubber powder and a softener in a mixer at 60-120 ℃ for 5-25 minutes to obtain a mixture, then conveying the mixture into a heat-preservation buffer tank kept at 60-120 ℃, conveying the mixture into a first counter-rotating twin-screw extruder (5) through a heat-preservation conveying metering device (1), wherein the mixture stays in the extruder (5) at 100-340 ℃ for 1-6 minutes to complete uniform permeation and primary desulfurization of the softener to the waste rubber powder, cooling the mixture to 40-80 ℃ under airtight condition in a continuous cooling device (6) to obtain a primary desulfurization material with Mooney viscosity of 100-230, continuously adding the primary desulfurization material into a second multi-screw extruder (10), adding a desulfurizing agent through a side feeding device, controlling the barrel and core shaft temperature of the multi-screw extruder to be 20-110 ℃, carrying out desulfurization reaction for 1-6 minutes to obtain desulfurized rubber powder with Mooney viscosity of 70-150, extruding the desulfurized rubber powder, cooling the desulfurized rubber powder to 25-60 ℃ in a continuous cooling device under a closed condition, continuously adding the desulfurized rubber powder into a third multi-screw extruder (14), controlling the temperature of a cylinder and a core shaft of the multi-screw extruder (14) to be-5-50 ℃, refining the desulfurized rubber powder for 1-10 minutes under a shearing condition, and finishing the refining process along with the extrusion of reclaimed rubber from the extruder. The third extruder (14) is cooled to below 50 ℃ through a forming device and a cooling device (15), and the required reclaimed rubber is obtained after packaging; wherein the mass ratio of the waste rubber powder to the softening agent to the desulfurizing agent is 100: (2-20): (0.01-3); the softening agent is one or the combination of coal tar, aromatic oil, pine tar, tall oil, dipentene, paraffin oil, oleic acid, cottonseed oil and rosin; the desulfurizer is one or the combination of aromatic disulfide, polyalkyl phenol sulfide, thiophenol and amine compounds; the waste rubber powder is one or the combination of waste radial truck tire powder and waste passenger car tire powder. The scheme does not mention the application of the prepared waste rubber to rubber asphalt and does not relate to the mixing condition of rubber powder in the asphalt.

CN102601975A A method for continuously preparing liquid reclaimed rubber by a screw extruder, the method for continuously preparing liquid reclaimed rubber by a screw extruder is characterized in that the screw extruder is utilized, a physical and chemical linkage method is adopted, and a three-dimensional cross-linked network of waste rubber is crushed by pretreated waste rubber powder under the comprehensive action of temperature, pressure, shearing and a desulfurizing agent in the extruder, but the method has low production efficiency and the pollution treatment method generated in the production process has defects. In addition, although this method proposes the preparation of rubber having a high degree of desulfurization depolymerization and its use for asphalt, there is no mention of the desulfurization degradation of butyl rubber and its use for low-noise asphalt pavement cements.

CN104830075A adopts butyl waste rubber to generate violent breakage of molecular chains under the action of peroxide at the temperature of more than 230 ℃, particularly about 250 ℃ to obtain a rubber material with low Mooney viscosity, wherein the sol content is high (more than 50 percent), so that a large amount of asphalt is added, and the addition amount of the waste rubber high-temperature cracking asphalt material is about 30 percent.

At present, a series of problems exist in a rubber powder pretreatment mode, the performance of rubber asphalt is not improved by optimizing a rubber de-crosslinking technology, and the dispersivity of a commercial de-crosslinked rubber product in the asphalt is often poor, so that the performance of the rubber asphalt cannot be guaranteed; secondly, when the rubber asphalt is prepared, the preparation process is not enough to lead the rubber to be fully grinded and dissolved in the asphalt, so that the composite modifier forms a compact interpenetration structure in the asphalt and comprehensively acts, thus the performance is not high; finally, the rubber mixing amount of the rubber asphalt is not high at present, so that the environmental protection and economic advantages of the rubber asphalt are not fully exerted.

Disclosure of Invention

In order to overcome the defects of the prior art, the invention provides the high-performance uncrosslinked rubber asphalt and the preparation method thereof, which solve the problem of dissolution and dispersion of rubber powder in asphalt and improve the performance and stability of the rubber asphalt.

The invention firstly provides a rubber powder crosslinking-releasing method for rubber asphalt, which comprises the following steps:

step (1) adopting a single screw extruder to carry out preliminary crosslinking treatment on the rubber powder: mixing 97-98% of rubber powder and 2-3% of softening oil, sealing and isolating oxygen at 260-300 ℃ and passing through a first section screw for 5-10 min, and then passing through a second section cooling screw for 3-7 min, wherein the discharging temperature is 50-60 ℃;

and (2) carrying out secondary crosslinking on the rubber powder by adopting an internal mixer, and simultaneously adding an isolation modifier for premixing treatment: adding 86-90% by mass of the pretreated rubber powder, 4-6% by mass of SBS modifier and 6-8% by mass of polyolefin modifier into an internal mixer, setting the rotating speed of the internal mixer to be 40-60 r/min and the covering air pressure to be 0.8-1.0 MPa, operating for 30-50 min, mixing materials and deeply decrosslinking the decrosslinked rubber powder, wherein the discharging temperature of the deeply decrosslinked rubber powder is 130-140 ℃, and extruding and granulating the rubber powder after passing through a single screw to form deeply decrosslinked rubber particles.

Wherein the rubber powder in the step (1) is waste rubber powder, such as waste rubber powder of tire treads or tire bodies, leftover bits and pieces, waste rubber shoes, waste butyl rubber, waste styrene-butadiene rubber, waste ethylene propylene diene monomer rubber and mixed rubber thereof, and the like, and the particle size range of the waste rubber powder is 20-40 meshes.

Wherein the softening oil is selected from one or more of aromatic oil, coal tar, pine tar, tall oil, naphthenic oil, dipentene, paraffin oil, oleic acid and rosin.

Wherein the polyolefin modifier in the step (2) is one or more selected from the group consisting of polyethylene wax with molecular weight of 1500-5000, polypropylene wax with molecular weight of 5000-10000, ethylene-propylene copolymer wax with molecular weight of 3000-800, maleic anhydride grafted polyethylene wax with molecular weight of 3000-8000 and maleic anhydride grafted polypropylene wax with molecular weight of 8000-15000.

Wherein the SBS modifier in the step (2) is one or more of linear SBS1301, SBS791-H and star SBS 4303.

The invention also provides rubber asphalt containing the rubber particles after rubber release, which comprises 65-70% of asphalt, 26-28% of rubber particles, 1.5-3% of SBS elastomer, 1-2% of blend oil and 0.1-0.2% of stabilizer.

The invention also provides an asphalt mixture containing the rubber asphalt.

Wherein the asphalt is selected from one of AH70 heavy-traffic petroleum asphalt and AH90 heavy-traffic petroleum asphalt.

Wherein the elastomer is selected from one or more of linear SBS1301, SBS791-H and star SBS 4303.

Wherein the blend oil is one or more selected from aromatic oil, coal tar, pine tar, tall oil, naphthenic oil, dipentene, paraffin oil, oleic acid and rosin.

Wherein the stabilizer is sulfur as main ingredient, and Sichuan family Louta KLT-WD can be used; shizhuangyuan chemical HMD-1; one or more of Foshan Xin Lu XLWD.

The invention also provides a preparation method of the rubber asphalt, which comprises the following steps:

(1) heating 65-70% of asphalt by mass, keeping the asphalt at 170-180 ℃, adding the rubber particles after dispergation prepared by the method, starting a shearing emulsifying machine to shear the rubber particles for 30-40 min at the speed of 4000-6000 r/min, then heating the asphalt to 190-200 ℃, slowly adding the prepared rubber particles after dispergation while the shearing emulsifying machine works, and shearing for 1.5-2 h to form rubber master batch with the modifier content of 35-45%;

(2) adding asphalt into the rubber master batch at 150-160 ℃, diluting the asphalt into rubber asphalt with a specified material proportion, taking 90-95 parts of diluted rubber asphalt, keeping the temperature of the asphalt at 180-190 ℃, adding 1.5-3% of SBS elastomer and 1-2% of blend oil, shearing at a shearing speed of 4000-6000 r/min for 50-60 min, adding 0.1-0.2% of stabilizer, and shearing for 5-10 min;

(3) and putting the sheared rubber asphalt into a stirring oven at 185-195 ℃, and developing for 1-1.5 h at a stirring speed of 500-700 r/min to obtain the rubber asphalt.

More preferably, the method comprises the following steps:

(1) heating 60 parts of AH70 heavy-traffic petroleum asphalt to 170-180 ℃, starting to add 10 parts of rubber particles after dispergation prepared by the method, starting a shearing emulsifying machine to shear the rubber particles for 30min at the speed of 5000r/min, then heating the asphalt to 190-200 ℃, slowly adding 30 parts of rubber particles after dispergation while the shearing emulsifying machine works, and shearing for 1.5h to form rubber master batch with the modifier content of 40%;

(2) adding 35 to 45 parts of 150 to 160 ℃ AH70 heavy-traffic petroleum asphalt into the rubber master batch, diluting the asphalt into rubber asphalt with a specified material proportion, taking 90 to 95 parts of diluted rubber asphalt, keeping the asphalt temperature at 180 to 190 ℃, adding 1.5 to 3 percent of SBS elastomer and 1 to 2 percent of blend oil, shearing for 55min at a shearing speed of 5000r/min, and then adding 0.1 to 0.2 percent of stabilizer and shearing for 5 min;

(3) and (3) putting the cut rubber asphalt into a stirring oven at 190 ℃, and developing for 1h at a stirring speed of 600 r/min.

When the rubber powder is deeply subjected to crosslinking decomposition, the polyolefin modifier and the SBS modifier (styrene-butadiene block polymer) are doped to serve as the separant of the uncrosslinked rubber, so that the viscosity of the uncrosslinked rubber can be reduced, and the cohesion of the uncrosslinked rubber is prevented. Meanwhile, when the asphalt is modified, the polyolefin modifier is quickly melted when meeting high temperature, and the colloidal particles are quickly opened, so that the dispersity of the rubber particles can be obviously enhanced. And simultaneously, the polyolefin and SBS modifier can obviously improve the performance of the asphalt. The invention adopts a secondary de-crosslinking process, adopts a single-screw extruder and an internal mixer to carry out deep de-crosslinking treatment on rubber powder, adopts a polyolefin modifier to improve the dissolving capacity of de-crosslinked rubber in many aspects, adopts a master batch method in the rubber asphalt processing stage to prevent rubber particles from popping out in a shearing machine in the shearing process and ensure that the shearing is not tight, so that the rubber is fully dissolved in the asphalt; the invention deeply degrades the uncrosslinked rubber, improves the cohesive force of the rubber asphalt, reduces the Brookfield viscosity of the rubber asphalt and improves the construction performance, thereby achieving higher rubber mixing amount and 25-30% of rubber powder mixing amount.

Has the advantages that:

(1) the invention adopts a secondary de-crosslinking process, adopts a single-screw extruder and an internal mixer to carry out deep de-crosslinking treatment on rubber powder, adopts a polyolefin modifier to improve the dissolving capacity of de-crosslinked rubber in many aspects, adopts a master batch method in the rubber asphalt processing stage to prevent rubber particles from popping out in a shearing machine in the shearing process and ensure that the shearing is not tight, so that the rubber is fully dissolved in the asphalt, the solubility of the rubber in the asphalt is obviously improved, the rubber and carbon black in vulcanized rubber powder are separated out, and the rubber and the carbon black can fully play a role in the asphalt.

(2) When the rubber powder is deeply subjected to crosslinking decomposition, the polyolefin modifier and the SBS modifier (styrene-butadiene block polymer) are doped to serve as the separant of the uncrosslinked rubber, so that the viscosity of the uncrosslinked rubber can be reduced, and the cohesion of the uncrosslinked rubber is prevented. Meanwhile, when the asphalt is modified, the polyolefin modifier is quickly melted when meeting high temperature, and the colloidal particles are quickly opened, so that the dispersity of the rubber particles can be obviously enhanced. And simultaneously, the performance of the rubber asphalt is obviously improved. The polyolefin modifier and the SBS modifier are difficult to use independently, and the release effect can be achieved only by using large amounts of the polyolefin modifier and the SBS modifier independently.

(3) The invention can make the mixing amount of the rubber powder reach 25 to 30 percent, obviously improves the mixing amount of the rubber powder in the rubber asphalt and obviously improves the economic and social benefits.

(4) Through the deep de-crosslinking technology of rubber and the process for preparing the rubber asphalt by adopting the master batch method, under the condition of higher mixing amount of the rubber and the SBS modifier, the kinematic viscosity of the asphalt can still be controlled within a reasonable range, a production pipeline is not easy to block, the workability of an asphalt mixture is good, compaction is easy, and the construction quality is guaranteed.

Drawings

FIG. 1 is a fluorescence microscopic image of uncrosslinked rubber asphalt in example 1

FIG. 2 comparative example 1 fluorescence microscopic image of uncrosslinked rubber asphalt

FIG. 3 fluorescent microscopic photograph of conventional rubberized asphalt of comparative example 2

FIG. 4 comparative example 3 fluorescent microscope picture of commercially available SBS modified asphalt (PG76-22)

Detailed Description

The technical solutions of the present application are further described below by the specific embodiments, but the present application is not limited thereto.

Example 1: the method is adopted to prepare the de-crosslinked rubber powder, the asphalt rubber is prepared by the method, and then the performance test of the asphalt and the asphalt mixture is carried out.

Firstly, carrying out primary de-crosslinking treatment on rubber powder by adopting a single-screw extruder, mixing 97.5 mass percent of 40-mesh waste tire rubber powder and 2.5 mass percent of aromatic oil, hermetically isolating oxygen at 280 ℃ to pass through a first section of screw for 6min, then cooling the screw through a second section of screw for 5min, and discharging at 60 ℃;

then, carrying out secondary crosslinking and premixing treatment on the rubber powder with an isolation modifier by using an internal mixer: adding 88 mass percent of the pretreated rubber powder, 5 mass percent of linear SBS791-H modifier and 7 mass percent of polyethylene wax into an internal mixer, setting the rotating speed of the internal mixer to be 50r/min, covering the internal mixer to have the air pressure of 0.9MPa, operating for 30min, mixing materials and deeply decrosslinking the decrosslinked rubber powder, wherein the discharging temperature of the deeply decrosslinked rubber powder is 140 ℃, and granulating the deeply decrosslinked rubber powder by a single-screw extruder at 140 ℃ to form deeply decrosslinked rubber granules.

The rubber asphalt is prepared from the following materials in proportion: 68.4 percent of AH70 heavy traffic petroleum asphalt, 27.9 percent of rubber particles, 2.1 percent of SBS, 1.5 percent of aromatic oil and 0.1 percent of stabilizer, and the concrete steps are as follows:

(1) heating 60 parts of AH70 heavy-traffic petroleum asphalt to 170-180 ℃, starting to add 10 parts of rubber particles after dispergation, starting a shearing emulsifying machine to shear the rubber particles for 30min at the speed of 5000r/min, then heating the asphalt to 195 ℃, slowly adding 30 parts of rubber particles after dispergation while the shearing emulsifying machine works, and shearing for 1.5h to form rubber master batch with the modifier content of 40%;

(2) adding 38 parts of 160 ℃ AH70 heavy-duty petroleum asphalt into a rubber master batch, diluting the asphalt into rubber asphalt with a specified material proportion, taking 96.3 parts of diluted rubber asphalt, keeping the asphalt temperature at 190 ℃, adding 2.1 parts of linear SBS791-H and 1.5 parts of blend oil, shearing for 55min at a shearing speed of 5000r/min, and then adding 0.1 part of SBS special stabilizer (KLT-WD) for shearing for 5 min;

(3) and (3) putting the sheared rubber asphalt into a stirring oven at 190 ℃, and developing for 1h at a stirring speed of 600r/min to obtain the rubber modified asphalt.

Comparative example 1: preparing the decrosslinked rubber powder which adopts calcium powder as the separant, then preparing the rubber modified asphalt, and performing the performance test of the asphalt and the asphalt mixture. The preparation method of the rubber asphalt comprises the following specific steps:

(1) carrying out preliminary decrosslinking treatment on rubber powder by adopting a single-screw extruder, mixing 97.5 mass percent of rubber powder with 2.5 mass percent of aromatic oil, hermetically isolating oxygen at 280 ℃ and passing through a first-stage screw for 6min, then cooling the screw at a second stage for 5min, extruding at 140 ℃, passing through a mixed solution of calcium powder and water to serve as an decrosslinked rubber particle isolating agent, and drying to form decrosslinked rubber particles;

(2) heating 68.4 parts of AH70 heavy-traffic petroleum asphalt, keeping the temperature to 160 ℃, adding 10 parts of rubber particles, starting a shearing emulsifying machine, shearing for 30min at a shearing speed of 5000r/min, then heating the asphalt, keeping the temperature to 195 ℃, slowly adding 16.5 parts of rubber particles, shearing for 1.5h at the same shearing speed, then adding 3.5% of SBS and 1.5% of aromatic oil, shearing for 55min at a shearing speed of 5000r/min, and then adding 0.1% of SBS special stabilizer (KLT-WD) and shearing for 5 min;

(3) and (3) putting the sheared rubber asphalt into a stirring oven at 190 ℃, and developing for 1h at a stirring speed of 600r/min to obtain the rubber modified asphalt.

Comparative example 2: preparing traditional rubber powder to prepare rubber asphalt, and performing performance tests on asphalt and asphalt mixture. The preparation method of the rubber asphalt comprises the following specific steps:

(1) heating 80 parts of AH70 heavy-duty petroleum asphalt, keeping the temperature to 160 ℃, adding 10 parts of 40-mesh rubber powder (which is not peptized), starting a shearing emulsifying machine, shearing at a shearing speed of 5000r/min for 30min, then heating the asphalt, keeping the temperature to 195 ℃, adding 10 parts of 40-mesh rubber powder, shearing at the same shearing speed for 30min, then adding 1.5 parts of aromatic oil, and shearing at a shearing speed of 5000r/min for 30 min;

(2) and (3) putting the sheared rubber asphalt into a stirring oven at 190 ℃, and developing for 1h at a stirring speed of 600r/min to obtain the rubber modified asphalt.

The rubber asphalt of the above example 1 and comparative examples 1 to 2 and the SBS modified asphalt (PG76-22) commonly used in the market (as comparative example 3) were compared, and the asphalt properties are shown in Table 1 and the asphalt properties are shown in Table 2.

TABLE 1 comparison of modified asphalt Properties

It can be seen that the uncrosslinked rubber asphalt prepared in example 1 of the present invention has a very high softening point, 5 ℃ elastic recovery and 60 ℃ dynamic viscosity, and a segregation softening point difference of only 0.7 ℃ which is much lower than that of other asphalt, compared with other rubber asphalt and SBS modified asphalt, which indicates that the rubber asphalt prepared by the present invention not only realizes high performance, but also has very high stability.

The rubber asphalt prepared in the embodiment 1 and the rubber asphalt prepared in the comparative example 1 are different in the selection of the release agent, the decrosslinking of the rubber powder and the preparation process of the rubber asphalt, the brookfield viscosity at 180 ℃ is greatly different, the brookfield viscosity at 180 ℃ of the comparative example 1 is 8.060pa.s, while the brookfield viscosity of the common rubber asphalt is 1.5pa.s-4.0pa.s, the brookfield viscosity of the comparative example 1 which is far beyond the range means that the workability of the asphalt mixture is poor and the asphalt mixture is not easy to compact, the brookfield viscosity of the rubber asphalt prepared in the embodiment 1 by adopting the invention is only 3.131pa.s, the brookfield viscosity requirement of the common rubber asphalt is met, and the workability of the asphalt mixture is good and the rubber asphalt is easy to compact.

The microscopic morphology of the modified asphalts was observed by magnifying the asphalts by 200 times using a fluorescence microscope, as shown in FIGS. 1-4.

The polymer modifiers such as rubber and SBS in the prepared uncrosslinked rubber asphalt are dispersed in the asphalt very uniformly, and the rubber and SBS form a very compact interpenetration structure; in comparative example 1, the rubber and SBS are dispersed in the asphalt, the rubber is flaky, and the SBS is flocculent and is dispersed in the asphalt, compared with the rubber asphalt prepared by the invention, the polymer is not sufficiently dispersed, and the formed structure is sparse; in the rubber asphalt prepared in comparative example 2, the rubber powder was present in the asphalt in a large local flake shape, and was very uneven; the above shows that the de-crosslinked rubber asphalt prepared by the invention has excellent dispersibility of the modifier. Comparative example 3 the SBS in the commercial product SBS modified asphalt (PG76-22) is uniformly dispersed to form a network structure, but the performance is far inferior to that of the uncrosslinked rubber asphalt prepared by the invention.

The mixture property tests were carried out on the uncrosslinked rubber asphalt prepared in example 1, the uncrosslinked rubber asphalt prepared in comparative example 1, the conventional rubber asphalt prepared in comparative example 2, and the conventional SBS-modified asphalt (PG76-22) commercially used in comparative example 3, and the SMA-13 asphalt mixture, and the results were as follows:

TABLE 2 comparison of SMA-13 asphalt mixture Properties

The uncrosslinked rubber asphalt SMA-13 asphalt mixture prepared by the invention has the advantages that the high-temperature dynamic stability and the low-temperature bending-pulling maximum damage strain are far higher than those of other asphalt mixtures, the water stability (freeze-thaw splitting strength ratio) is also far higher than the requirement that the current specification is more than or equal to 80%, the asphalt-stone ratio is obviously reduced compared with two comparative rubber asphalts, the economy is excellent, and the high performance of the rubber asphalt and the mixture is realized.

Claims (10)

1. A rubber powder dispergation method for rubber asphalt is characterized by comprising the following steps:

step (1) adopting a single screw extruder to carry out preliminary crosslinking treatment on the rubber powder: mixing 97-98% of rubber powder and 2-3% of softening oil, sealing and isolating oxygen at 260-300 ℃ and passing through a first section screw for 5-10 min, and then passing through a second section cooling screw for 3-7 min, wherein the discharging temperature is 50-60 ℃;

and (2) carrying out secondary crosslinking on the rubber powder by adopting an internal mixer, and simultaneously adding an isolation modifier for premixing treatment: adding 86-90% by mass of the pretreated rubber powder, 4-6% by mass of SBS modifier and 6-8% by mass of polyolefin modifier into an internal mixer, setting the rotating speed of the internal mixer to be 40-60 r/min and the covering air pressure to be 0.8-1.0 MPa, operating for 30-50 min, mixing materials and deeply decrosslinking the decrosslinked rubber powder, wherein the discharging temperature of the deeply decrosslinked rubber powder is 130-140 ℃, and extruding and granulating the rubber powder after passing through a single screw to form deeply decrosslinked rubber particles.

2. The method for decrosslinking rubber crumb used in rubber asphalt as claimed in claim 1, wherein said rubber crumb in step (1) is waste rubber crumb.

3. The method as claimed in claim 2, wherein the softening oil is selected from one or more of aromatic oil, coal tar, pine tar, tall oil, naphthenic oil, dipentene, paraffin oil, oleic acid and rosin.

4. The method as claimed in claim 1, wherein the polyolefin modifier in step (2) is selected from one or more of polyethylene wax with molecular weight of 1500-.

5. The method for disperging rubber powder used for rubber asphalt as claimed in claim 1, wherein the SBS modifier in the step (2) is one or more of linear SBS1301, SBS791-H and star SBS 4303.

6. A rubber asphalt is characterized by comprising the following components: 65-70% of asphalt by mass, 26-28% of rubber particles by mass, 1.5-3% of SBS elastomer by mass, 1-2% of blend oil by mass and 0.1-0.2% of stabilizer by mass, wherein the rubber particles are the rubber particles after peptization prepared according to any one of claims 1-5.

7. The rubber asphalt of claim 6, wherein the asphalt is selected from one of AH70 heavy-duty petroleum asphalt and AH90 heavy-duty petroleum asphalt.

8. The rubber asphalt of claim 7, wherein the elastomer is selected from one or more of linear SBS1301, SBS791-H and star SBS 4303.

9. The process for producing rubberized asphalt according to any one of claims 6 to 8, characterized by comprising the steps of:

(1) heating 65-70% by mass of asphalt and keeping the temperature to 170-180 ℃, adding the rubber particles after dispergation prepared by any one of claims 1-5, starting a shearing emulsifying machine to shear the rubber particles for 30-40 min at the speed of 4000-6000 r/min, then heating the asphalt and keeping the temperature to 190-200 ℃, slowly adding the rubber particles after dispergation prepared by any one of claims 1-5 while the shearing emulsifying machine works, and shearing for 1.5-2 h to form a rubber master batch with the modifier content of 35-45%;

(2) adding asphalt into the rubber master batch at 150-160 ℃, diluting the asphalt into rubber asphalt with a specified material proportion, taking 90-95 parts of diluted rubber asphalt, keeping the temperature of the asphalt at 180-190 ℃, adding 1.5-3% of elastomer and 1-2% of blend oil, shearing at a shearing speed of 4000-6000 r/min for 50-60 min, adding 0.1-0.2% of stabilizer, and shearing for 5-10 min;

(3) and putting the sheared rubber asphalt into a stirring oven at 185-195 ℃, and developing for 1-1.5 h at a stirring speed of 500-700 r/min to obtain the rubber asphalt.

10. Asphalt mixture comprising the rubber asphalt of any one of claims 6 to 8.

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