A micro-modified rubber powder

Abstract

The present application relates to a kind of micro-modified rubber powder, belong to road engineering technical field, solve the problem of poor workability of rubber modified asphalt prepared by using existing rubber powder when applied to national and provincial trunk lines and urban highways.The preparation raw materials of the micro-modified rubber powder include 100 parts of rubber powder, 5-10 parts of softening oil, 0.1-0.2 parts of activator;It also includes water, and the mass fraction of water is 3-10 parts.The 135℃ viscosity of the rubber modified asphalt prepared by using the micro-modified rubber powder of the present application is 0.3-0.9Pa·s, and has good workability.

Description

Technical Field

[0001] This invention relates to the field of road engineering technology, and in particular to a micro-modified adhesive powder. Background Technology

[0002] In recent years, with the rapid development of my country's transportation industry, the progress of its economy, and the increase in car ownership, highway construction has experienced unprecedented growth. In particular, the emergence of various high-performance modified asphalt and other new materials has greatly promoted the development of high-grade highways. However, most traditional national and provincial trunk roads and urban roads are paved with base asphalt, and the existing pavement performance can no longer adequately meet current traffic demands. Furthermore, the average maintenance cycle is still significantly shorter than the designed service life, making pavement durability a major obstacle to its development. Therefore, promoting high-quality development of national and provincial trunk roads and urban roads is an important development direction for the present and for some time to come.

[0003] While existing rubber-modified asphalt has improved road performance to some extent, it is mainly designed for first-class roads such as expressways, and its workability is poor when applied to national and provincial trunk roads and urban roads. Summary of the Invention

[0004] Based on the above analysis, the present invention aims to provide a micro-modified rubber powder to solve the problem of poor workability of rubber-modified asphalt prepared using existing rubber powder when applied to national and provincial trunk roads and urban highways.

[0005] The objective of this invention is mainly achieved through the following technical solutions:

[0006] On one hand, the present invention provides a micro-modified adhesive powder, wherein the raw materials for preparing the micro-modified adhesive powder include 100 parts of adhesive powder, 5-10 parts of softening oil, and 0.1-0.2 parts of activator; and also include water, wherein the mass fraction of water is 3-10 parts.

[0007] Furthermore, the softening oil includes any one or a mixture of palm oil, aromatic oil, and fatty acids.

[0008] Furthermore, the softened oil also includes any one or a mixture of several of epoxidized soybean oil, coal tar, and vegetable oil.

[0009] Furthermore, the activator includes one or a mixture of several of activator 980, activator 580 and activator 950.

[0010] Furthermore, the activator also includes one or a mixture of activator 480 and activator 420.

[0011] Furthermore, the rubber powder comes from recycled waste tires.

[0012] Furthermore, the mesh size of the adhesive powder is 20-40 mesh.

[0013] Furthermore, the water comprises 4-6 parts by mass.

[0014] Furthermore, the water comprises 5 parts by mass.

[0015] On the other hand, the present invention also provides a method for preparing micro-modified adhesive powder, which includes a first activation and a second activation of the adhesive powder. Specifically, it includes the following steps:

[0016] Step 1: Perform the first activation of the adhesive powder and then cool it;

[0017] Step 2: The cooled adhesive powder is activated a second time to obtain micro-modified adhesive powder.

[0018] Furthermore, in step 1, the first activation of the adhesive powder includes the following steps:

[0019] Step 11: Mix the adhesive powder, softening oil, activator, and water to obtain a mixture;

[0020] Step 12: Desulfurize the mixture under high temperature and high pressure for a certain period of time.

[0021] Furthermore, the initial activation temperature is 210–240°C.

[0022] Furthermore, step 11 is carried out in a desulfurization tank.

[0023] Furthermore, in step 1, the activated adhesive powder is cooled to room temperature.

[0024] Furthermore, the desulfurization time in step 12 is 50-70 minutes.

[0025] Furthermore, the rubber powder comes from recycled waste tires.

[0026] Furthermore, step 2 is performed in a screw extruder.

[0027] Furthermore, the screw extruder is a three-screw extruder.

[0028] Compared with the prior art, the present invention can achieve at least one of the following beneficial effects:

[0029] (1) Existing rubber-modified asphalt is mainly designed for Class I roads such as expressways, and its workability is poor when applied to national and provincial trunk roads and urban roads. This invention improves the activity of rubber powder and its compatibility with the base asphalt by using a two-step activation process, thereby controlling the viscosity of the modified asphalt at 135℃ to 0.3-0.9 Pa·s. This makes the modified asphalt of this invention have good workability when applied to national and provincial trunk roads and urban roads.

[0030] (2) Existing technologies for preparing modified asphalt involve mixing untreated raw rubber powder with base asphalt and stirring for over 3 hours. This invention slightly modifies the rubber powder, effectively shortening the swelling and development time of the slightly modified rubber powder in the base asphalt (development time is only 10-20 minutes), and eliminates the need for shearing, simplifying the preparation process of rubber-modified asphalt and significantly increasing production capacity. Furthermore, the preparation method of modified asphalt in this invention is a continuous production process, where the slightly modified rubber powder is directly swollen and developed with the base asphalt to obtain modified asphalt, further improving production capacity. Specifically, this invention achieves dynamic desulfurization of the rubber powder by stirring it with an activator, softening oil, and water in a desulfurization tank, putting the rubber powder in an active state—this is the first step in activating the rubber powder. The active rubber powder is then extruded through a high-temperature screw extruder, which further restores the rubber properties of the rubber powder, making it more compatible with the base asphalt, thus enabling the slightly modified rubber powder to react rapidly with the base asphalt.

[0031] (3) By controlling the temperature and pressure of the first activation step (210-240℃, 15.3-18.6MPa) and controlling the screw temperature in the second activation step to a specific 190-210℃, the present invention further improves the activity of the rubber powder, thereby further improving the reaction between the rubber powder and the base asphalt, shortening the swelling development time, and making it more conducive to controlling the viscosity of the modified asphalt.

[0032] (4) The micro-modified rubber asphalt prepared by the method of the present invention has an asphalt-aggregate ratio and material cost comparable to that of base asphalt, resulting in a lower overall road construction cost. However, its high and low temperature performance is significantly superior to that of base asphalt. Furthermore, the rubber powder of the present invention is derived from waste tires, and it is expected to provide a more guiding and referential new technology for related engineering applications, while also bringing good environmental and social benefits.

[0033] (5) Modified asphalt prepared by existing technology has poor compatibility with the base asphalt because the rubber powder is in the form of particles, and segregation and stratification will occur after long-term storage. The micro-modified rubber powder prepared by the preparation method of the present invention has good compatibility with the base asphalt, and the modified asphalt can be stored under heat for a long time without segregation and stratification.

[0034] (6) Because in existing technologies, the reaction between raw rubber powder and base asphalt requires the addition of a large amount of other additives, the amount of rubber powder is only 10%-20% of the mass of the modified asphalt. In the micro-modified rubber powder preparation method of the present invention, the amount of additives added is very small relative to the amount of rubber powder, for example, 100 parts rubber powder, 5-10 parts softening oil, 0.1-0.2 parts activator, and 3-10 parts water. Therefore, the present invention can recycle a large amount of waste rubber powder, which on the one hand reduces production costs; on the other hand, it can bring good environmental and social benefits.

[0035] In this invention, the above-described technical solutions can be combined with each other to achieve more preferred combinations. Other features and advantages of this invention will be set forth in the following description, and some advantages will become apparent from the description or may be learned by practicing the invention. Detailed Implementation

[0036] One specific embodiment of the present invention discloses a micro-modified adhesive powder. The raw materials for preparing the micro-modified adhesive powder, by weight, include 100 parts adhesive powder, 3-10 parts water, 5-10 parts softening oil, and 0.1-0.2 parts activator.

[0037] In one embodiment, the softening oil is any one or a mixture of several of palm oil, aromatic oil, epoxidized soybean oil, coal tar, vegetable oil, and fatty acids.

[0038] In one embodiment, the activator is one or a mixture of several of activators 980, 580, 480, 420, and 950.

[0039] In one embodiment, the rubber powder of the present invention is derived from recycled waste tires and has a mesh size of 20-40 mesh.

[0040] Another specific embodiment of the present invention discloses a method for preparing micro-modified adhesive powder, which includes the following steps:

[0041] Step 1: Activate the adhesive powder for the first time and cool it to room temperature.

[0042] Step 2: The cooled rubber powder undergoes a second activation to obtain slightly modified rubber powder. This specifically includes the following steps: The cooled material is fed into a screw extruder for shearing, with the extrusion temperature controlled at 190–210℃. For example, temperatures could be 190℃, 195℃, 200℃, 205℃, or 210℃. In Step 1, the cooling process prevents the rubber powder from accumulating. Specifically, cooling after high-temperature oxidation (first activation) makes the rubber powder fluffy and easier to handle. Step 1 specifically includes the following steps:

[0043] Step 11: Mix the adhesive powder, softening oil, activator and water, stir well to obtain the mixture.

[0044] Step 12: Desulfurize the mixture under high temperature and high pressure for a certain period of time. This specifically includes the following steps:

[0045] The desulfurization tank is heated and pressurized to desulfurize the mixture.

[0046] Specifically, in step 11, the rubber powder is added to the desulfurization tank according to the formula weight; then, the softening oil, activator and water are added to the desulfurization tank according to the formula weight and stirred evenly.

[0047] In one embodiment, the adhesive powder is 100 parts and the softening oil is 5-10 parts. For example, it can be 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts.

[0048] Specifically, softened oil is any one or a mixture of several of the following: palm oil, aromatic oil, epoxidized soybean oil, coal tar, vegetable oil, and fatty acids.

[0049] In one embodiment, the activator is 0.1-0.2 parts. For example, it can be 0.1 parts, 0.15 parts, or 0.2 parts.

[0050] Specifically, the activator is one or a mixture of several of the following: Activator 980, Activator 580, Activator 480, Activator 420, and Activator 950.

[0051] In one embodiment, the amount of water is 3-10 parts. For example, it can be 3 parts, 4 parts, 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, or 10 parts. Preferably, it is 5 parts. The purpose of adding water in this embodiment is to regulate the pressure inside the desulfurization tank (i.e., the pressure for the first activation of the rubber powder) through the evaporation of water.

[0052] The rubber powder of this invention is derived from recycled waste tires, with a mesh size of 20-40 mesh. For example, it can be 20 mesh, 25 mesh, 30 mesh, 35 mesh, or 40 mesh. A mesh size higher than 40 mesh increases production costs; a mesh size lower than 20 mesh, under the same processing conditions, results in incomplete processing of the rubber powder by the screw, leading to the presence of rubber powder particles.

[0053] Specifically, in step 12, the temperature inside the desulfurization tank is 210–240℃. For example, it can be 210℃, 215℃, 220℃, 225℃, 230℃, 235℃, or 240℃.

[0054] In one embodiment, the pressure inside the desulfurization tank is 15.3 to 18.6 MPa. For example, it can be 15.3 MPa, 16 MPa, 16.5 MPa, 17 MPa, 17.5 MPa, 18 MPa, or 18.6 MPa.

[0055] In one embodiment, the desulfurization time is 50-70 minutes. For example, it can be 50 minutes, 55 minutes, 60 minutes, 65 minutes, or 70 minutes. Preferably, it is 60 minutes.

[0056] Another specific embodiment of the present invention discloses a method for preparing micro-modified rubber asphalt, comprising: reacting the micro-modified rubber powder prepared by the above method with base asphalt to obtain micro-modified rubber asphalt. Specifically, it includes the following steps:

[0057] Step a: Add the base bitumen to the reactor and heat it to 185°C, then keep it at that temperature;

[0058] Step b: Add the micro-modified rubber powder extruded from the screw extruder into the reaction vessel and stir rapidly to allow the micro-modified rubber powder to react with the base asphalt to obtain modified asphalt.

[0059] Specifically, the developmental reaction temperature is 185℃, and the developmental reaction time is 10-20 minutes. For example, it can be 10 minutes, 12 minutes, 14 minutes, 16 minutes, 18 minutes, or 20 minutes.

[0060] Specifically, the stirring speed in step 2 is 500-800 rpm. For example, it can be 500 rpm, 600 rpm, 700 rpm, and 800 rpm.

[0061] In one embodiment, the mass ratio of base asphalt to micro-modified rubber powder is (80-95):(20-5). For example, the base asphalt is 80 parts and the micro-modified rubber powder is 20 parts; the base asphalt is 85 parts and the micro-modified rubber powder is 15 parts; the base asphalt is 90 parts and the micro-modified rubber powder is 10 parts; the base asphalt is 95 parts and the micro-modified rubber powder is 5 parts.

[0062] The use of the micro-modified rubber powder of this invention to prepare rubber-modified asphalt significantly shortens the swelling and development time of the micro-modified rubber powder in the base asphalt (the development time of the prior art is more than 3 hours, while the development time of this invention is only 10-20 minutes), and improves the activity of the rubber powder and its compatibility with the base asphalt. As a result, the viscosity of the modified asphalt at 135℃ is controlled at 0.3-0.9 Pa·s, making the modified asphalt of this invention have good workability when applied to national and provincial trunk roads and urban highways.

[0063] Example 1

[0064] (1) Weigh 100 parts of rubber powder and add it to the desulfurization tank. Then weigh 6 parts of aromatic oil, 0.1 parts of activator 580 and 4 parts of water and add them to the desulfurization tank. Stir well.

[0065] (2) Pressurize the desulfurization tank to 15.3 MPa and heat it to 240℃;

[0066] (3) Desulfurization treatment for 50 min;

[0067] (4) Cool to room temperature after desulfurization is completed;

[0068] (5) The cooled material is fed into a three-screw extruder for shearing, with the temperature controlled at 190℃;

[0069] (6) The micro-modified rubber powder extruded from the three-screw extruder was added to the asphalt reactor. The temperature in the reactor was maintained at 185℃. The mass ratio of 70# base asphalt to micro-modified rubber powder was 95:5. The two were rapidly stirred and developed for 10 minutes, and then pumped out to obtain modified asphalt. The modified asphalt was tested for its properties, and the results are shown in Table 1.

[0070] Example 2

[0071] (1) Weigh 100 parts of rubber powder and add it to the desulfurization tank. Then weigh 10 parts of palm oil, 0.2 parts of activator 980 and 8 parts of water and add them to the desulfurization tank. Stir well.

[0072] (2) Pressurize the desulfurization tank to 18.6 MPa and heat it to 210℃;

[0073] (3) Desulfurization treatment for 70 minutes;

[0074] (4) Cool to room temperature after desulfurization is completed;

[0075] (5) The cooled material is fed into a three-screw extruder for shearing, with the temperature controlled at 210℃;

[0076] (6) The micro-modified rubber powder extruded from the three-screw extruder was added to the asphalt reactor. The temperature in the reactor was maintained at 185℃. The mass ratio of 70# base asphalt to micro-modified rubber powder was 90:10. The two were rapidly stirred and developed for 20 minutes, and then pumped out to obtain modified asphalt. The modified asphalt was tested for its properties, and the results are shown in Table 1.

[0077] Example 3

[0078] (1) Weigh 100 parts of rubber powder and add it to the desulfurization tank. Then weigh 7 parts of fatty acid, 0.1 parts of activator 950 and 6 parts of water and add them to the desulfurization tank. Stir well.

[0079] (2) Pressurize the desulfurization tank to 17.5 MPa and heat it to 220°C;

[0080] (3) Desulfurization treatment for 60 min;

[0081] (4) Cool to room temperature after desulfurization is completed;

[0082] (5) The cooled material is fed into a three-screw extruder for shearing, with the temperature controlled at 205℃;

[0083] (6) The micro-modified rubber powder extruded from the three-screw extruder was added to the asphalt reactor. The temperature in the reactor was maintained at 185℃. The mass ratio of 70# base asphalt to micro-modified rubber powder was 85:15. The two were rapidly stirred and developed for 12 minutes, and then pumped out to obtain modified asphalt. The modified asphalt was tested for its properties, and the results are shown in Table 1.

[0084] Example 4

[0085] (1) Weigh 100 parts of rubber powder and add it to the desulfurization tank. Then weigh 8 parts of vegetable oil, 0.15 parts of activator 420 and 5 parts of water and add them to the desulfurization tank. Stir well.

[0086] (2) Pressurize the desulfurization tank to 16.5 MPa and heat it to 235°C;

[0087] (3) Desulfurization treatment for 60 min;

[0088] (4) Cool to room temperature after desulfurization is completed;

[0089] (5) The cooled material is fed into a three-screw extruder for shearing, with the temperature controlled at 200℃;

[0090] (6) The micro-modified rubber powder extruded from the three-screw extruder was added to the asphalt reactor. The temperature in the reactor was maintained at 185℃. The mass ratio of 70# base asphalt to micro-modified rubber powder was 80:20. The two were rapidly stirred and developed for 16 minutes, and then pumped out to obtain modified asphalt. The modified asphalt was tested for its properties, and the results are shown in Table 1.

[0091] Table 1 Test results of modified asphalt performance indicators

[0092]

[0093]

[0094] As shown in Table 1, with the increase of the amount of micro-modified rubber powder, the viscosity of micro-modified rubber asphalt also increases. The ductility at 5℃, the dynamic stability of the asphalt mixture, and the low-temperature bending performance of the asphalt mixture are all effectively improved and are higher than the technical indicators of 70# base asphalt, indicating that the quality of micro-modified rubber asphalt is better than that of 70# base asphalt.

[0095] Comparative Example 1

[0096] The raw materials used in this comparative example are the same as those used in Example 3 in terms of type and amount, and the preparation method is roughly the same as that in Example 3. The difference is that the desulfurization tank is pressurized to 14.5 MPa.

[0097] The modified asphalt prepared had a rotational viscosity of 1.5 Pa·s at 135°C, exhibiting poor workability and unsuitability for national and provincial highways and urban roads. Other indicators were similar to those in Example 3.

[0098] Comparative Example 2

[0099] The raw materials used in this comparative example are the same as those used in Example 3 in terms of type and amount, and the preparation method is roughly the same as that in Example 3. The difference is that the desulfurization tank is pressurized to 19.5 MPa.

[0100] The modified asphalt prepared had a rotational viscosity of 0.15 Pa·s at 135°C, exhibiting poor workability and unsuitability for national and provincial highways and urban roads. Other properties were similar to those in Example 3.

[0101] As can be seen from Comparative Document 1 and Comparative Example 2, the activation pressure in the first step was not within the range of 15.3-18.6 MPa. The resulting modified asphalt had a rotational viscosity at 135°C that was either too high or too low, resulting in poor workability and making it unsuitable for national and provincial highways and urban roads. Other indicators were similar to those in Example 3.

[0102] Comparative Example 3

[0103] The raw materials used in this comparative example are the same as those in Example 3 in terms of type and amount, and the preparation method is roughly the same as that in Example 3. The difference is that the desulfurization tank is heated to 250°C, and the swelling and development time of the slightly modified rubber powder and the base asphalt is as high as 5 hours. Other indicators are similar to those in Example 3.

[0104] Comparative Example 4

[0105] The raw materials used in this comparative example are the same as those in Example 3 in terms of type and amount, and the preparation method is roughly the same as that in Example 3. The difference is that the desulfurization tank is heated to 205°C, and the swelling and development time of the slightly modified rubber powder and the base asphalt is as high as 8 hours. Other indicators are similar to those in Example 3.

[0106] As can be seen from Comparative Document 3 and Comparative Example 4, the activation temperature in the first step is not within the range of 210-240℃. During the preparation of modified asphalt, the swelling and development time of the micro-modified rubber powder and the base asphalt increases significantly, and the production efficiency decreases significantly.

[0107] Comparative Example 5

[0108] The raw materials used in this comparative example are the same as those in Example 3 in terms of type and amount, and the preparation method is roughly the same as that in Example 3. The difference is that the temperature of the three-screw extruder is controlled at 180°C.

[0109] The modified asphalt prepared had a rotational viscosity of 0.1 Pa·s at 135°C, exhibiting poor workability and unsuitability for national and provincial highways and urban roads. Other indicators were similar to those in Example 3.

[0110] Comparative Example 6

[0111] The raw materials used in this comparative example are the same as those in Example 3 in terms of type and amount, and the preparation method is roughly the same as that in Example 3. The difference is that the temperature of the three-screw extruder is controlled at 215°C.

[0112] The modified asphalt prepared had a rotational viscosity of 1.9 Pa·s at 135°C, exhibiting poor workability and unsuitability for national and provincial highways and urban roads. Other indicators were similar to those in Example 3.

[0113] As can be seen from Comparative Document 5 and Comparative Example 6, the activation temperature in the second step is not within the range of 190-210℃. The modified asphalt prepared has a rotational viscosity at 135℃ that is too high or too low, resulting in poor workability and making it unsuitable for national and provincial trunk roads and urban highways.

[0114] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A slightly modified adhesive powder, characterized in that, The raw materials for preparation include 100 parts of adhesive powder, 5-10 parts of softening oil, and 0.1-0.2 parts of activator; It also includes water, in parts by mass of 3-10; The micro-modified adhesive powder is prepared by the following method: Step 1: Perform the first activation of the adhesive powder and then cool it; Step 2: The cooled adhesive powder is activated a second time to obtain micro-modified adhesive powder; Step 1, the first activation of the adhesive powder, includes the following steps: Step 11: Mix the adhesive powder, softening oil, activator, and water to obtain a mixture; Step 12: Desulfurize the mixture under high temperature and high pressure of 210~240℃ and 15.3~18.6MPa; Step 2 involves a second activation of the cooled rubber powder, including the following steps: the cooled material is fed into a screw extruder for shearing, with an extrusion temperature of 205~210℃.

2. The micro-modified adhesive powder according to claim 1, characterized in that, The softened oil includes any one or a mixture of several of palm oil, aromatic oil, epoxidized soybean oil, and coal tar.

3. The micro-modified adhesive powder according to claim 1, characterized in that, The activator includes one or a mixture of several of activator 980, activator 580 and activator 950.

4. The micro-modified adhesive powder according to claim 3, characterized in that, The activator also includes one or a mixture of activator 480 and activator 420.

5. The micro-modified adhesive powder according to claim 1, characterized in that, The rubber powder comes from recycled waste tires.

6. The micro-modified adhesive powder according to claim 5, characterized in that, The mesh size of the adhesive powder is 20-40 mesh.

7. The micro-modified adhesive powder according to claim 1, characterized in that, The water comprises 4-6 parts by mass.

8. The micro-modified adhesive powder according to claim 1, characterized in that, The water has a mass fraction of 5 parts.

9. A method for preparing a micro-modified adhesive powder, characterized in that, The preparation method is used to prepare the micro-modified adhesive powder according to any one of claims 1-8, the preparation method comprising a first activation and a second activation of the adhesive powder; The micro-modified adhesive powder is prepared by the following method: Step 1: Perform the first activation of the adhesive powder and then cool it; Step 2: The cooled adhesive powder is activated a second time to obtain micro-modified adhesive powder; Step 1, the first activation of the adhesive powder, includes the following steps: Step 11: Mix the adhesive powder, softening oil, activator, and water to obtain a mixture; Step 12: Desulfurize the mixture under high temperature and high pressure of 210~240℃ and 15.3~18.6MPa; Step 2 involves a second activation of the cooled rubber powder, including the following steps: the cooled material is fed into a screw extruder for shearing, with an extrusion temperature of 205~210℃.

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