JP2009209534A - Storage method for asphalt rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a storage method for an asphalt rubber, which can suppress a decrease in the concentration of rubber powder by suppressing the decomposition of the rubber powder in the asphalt rubber during heating storage. <P>SOLUTION: This storage method for the asphalt rubber, in which the rubber powder is contained in asphalt, is characterized in that the asphalt rubber is heated and stored at 150-175°C, suitably, at 165-175°C. The storage method can be suitably applied to the asphalt rubber using straight asphalt as the asphalt and using rubber powder, obtained by crushing a waste tire, as the rubber powder. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for storing asphalt rubber, and more particularly to a method for storing asphalt rubber that can suppress a decrease in the concentration of rubber powder in the asphalt rubber during heat storage.

  Conventionally, it is known to use rubber obtained by pulverizing waste tires as an elastic pavement material. When this elastic pavement material is applied to a sidewalk, the elasticity of rubber has an effect on shock absorption and safety in the event of a fall. In addition to performance and breathability, it has excellent sound absorption, and is therefore effective in reducing noise generated on the tire and road surface. However, due to the elasticity of rubber, compaction tends to be insufficient, and wear tends to occur, leaving a problem in durability.

  Also known is an asphalt rubber in which rubber powder obtained by pulverizing waste tires is mixed with asphalt. When using asphalt rubber instead of ordinary asphalt, it is said that the film covering the aggregate such as stone and sand is thickened, the durability of the pavement is improved, and cracking is difficult to occur. Such asphalt rubber is produced by adding a predetermined amount of rubber powder of waste tires to heated and melted straight asphalt, stirring and mixing at a predetermined temperature, and then aging the mixture at a predetermined temperature. Normally, rubber powder is used that is obtained by pulverizing waste tires such as buses and trucks (hereinafter referred to as “TB rubber powder”), and stirring, mixing, and aging are performed at 180 ° C. (for example, Patent Document 1).

The feature of such asphalt rubber is that TB rubber powder swells and is reformed into a high-viscosity binder, and thus, it is said that performance similar to that of modified asphalt can be expected. It has been reported that the asphalt rubber thus obtained is excellent in fluid resistance, wear resistance, fatigue resistance, slip resistance, weather resistance and the like.
JP 2006-328139 A (Claims etc.)

  In Japan, asphalt binders are often stored by heating because of the large number of small-lot shipments on site. This applies not only to straight asphalt but also to other modified asphalts. However, this heat storage has the disadvantage that the added rubber powder is decomposed, the rubber powder concentration is lowered, and the rubber powder concentration expected for the asphalt rubber cannot be maintained.

  Accordingly, an object of the present invention is to provide a storage method of asphalt rubber that can suppress the decomposition of rubber powder in the asphalt rubber during heat storage and suppress the decrease in the concentration of rubber powder.

  As a result of intensive studies, the present inventors have found that by setting the temperature during heating and storage within a predetermined range, it is possible to suppress a decrease in the concentration of rubber powder due to the decomposition of the rubber powder, and to complete the present invention. It came.

  That is, the asphalt rubber storage method of the present invention is characterized in that in the asphalt rubber storage method in which rubber powder is contained in asphalt, the asphalt rubber is heated and stored at 150 to 175 ° C.

  In this invention, it is preferable to make the temperature at the time of heat storage of asphalt rubber into the range of 165-175 degreeC. In the present invention, the asphalt is preferably straight asphalt, and in the present invention, it is preferable that the rubber powder is a rubber powder obtained by pulverizing a waste tire. Furthermore, the asphalt rubber is a melting step in which the asphalt is heated to melt, an addition step in which the rubber powder is added while stirring the asphalt at a melting temperature or higher after melting, and stirring after the addition while maintaining the melting temperature or higher. It is preferable that the asphalt rubber manufactured through a stirring process that continues to be performed and an aging process that is aged in a thermostat after stirring.

  According to the present invention, the above configuration makes it possible to suppress a decrease in the rubber powder concentration due to the decomposition of the rubber powder in the asphalt rubber even when the asphalt rubber is heated and stored.

Hereinafter, preferred embodiments of the present invention will be described in detail.
In the asphalt rubber storage method of the present invention, it is important to set the heating storage temperature in the range of 150 to 175 ° C, and preferably the heating storage temperature is in the range of 165 to 175 ° C. If the heat storage temperature is less than 150 ° C., the decomposition of the rubber powder can be suppressed, but the melted state of the asphalt and the rubber powder becomes very poor. On the other hand, when it exceeds 175 ° C., the rubber powder is decomposed, and the predetermined rubber powder concentration cannot be maintained.

  As an asphalt rubber to which the present invention can be suitably applied, there is an asphalt rubber obtained by adding rubber powder to straight asphalt. Examples of straight asphalt include straight asphalt 40/60, 60/80, 80/100, and 100/120. These can be used alone or in combination of two or more. The asphalt may be decolorized asphalt.

  Further, the rubber powder in the asphalt rubber to which the present invention can be suitably applied is not particularly limited, but is preferably a rubber powder obtained by pulverizing a waste tire. Examples of the rubber powder obtained by crushing the waste tire include TB rubber powder and rubber powder obtained by crushing the waste tire for passenger cars (hereinafter referred to as “PS rubber powder”). In obtaining the desired effect, Is more preferably PS rubber powder. By using the rubber powder obtained by crushing the waste tire, the waste tire is recycled, which can contribute to solving pollution problems such as illegal dumping of the waste tire.

  In addition, asphalt rubber, if necessary, as a color pigment, UV absorber, antioxidant, adhesion improver, anti-aging agent, metal deactivator, light stabilizer, foaming agent, moisture remover, It may be blended with a diluent solvent, a polymer for adjusting physical properties or a low molecular additive.

Next, the manufacturing method of the asphalt rubber which can apply the asphalt rubber storage method of this invention suitably is demonstrated.
The asphalt rubber production method to which the asphalt rubber storage method of the present invention can be suitably applied includes a melting step of heating and melting the asphalt, and adding rubber powder while stirring the asphalt at a melting temperature or higher after melting. It includes an addition step, a stirring step in which stirring is continued while maintaining the melting temperature or higher after the addition, and an aging step in which aging is performed in a thermostat after the stirring.

  In the melting step, the heating and melting temperature of asphalt is preferably in the range of 130 ° C to 180 ° C. This is because the asphalt is not sufficiently melted at a temperature lower than 130 ° C., whereas the melting effect does not change when the temperature exceeds 180 ° C.

  In the addition step, the temperature at which the rubber powder is added to the heat-melted asphalt is preferably 150 ° C to 200 ° C. If the temperature is lower than 150 ° C., the rubber powder is not sufficiently gelled. On the other hand, if the temperature exceeds 200 ° C., the asphalt is thermally deteriorated. At this time, the addition of the rubber powder may be carried out while stirring the melted asphalt or after the addition. However, considering the promotion of gelation and uniform mixing of the rubber powder, the asphalt is stirred. It is preferable to add it. At this time, the stirring speed is preferably 50 rpm to 3000 rpm. This is because when the stirring speed is less than 50 rpm, the added rubber powder is insufficiently dispersed and a uniform mixture cannot be obtained. On the other hand, even if it exceeds 3000 rpm, the stirring effect does not change.

  In the stirring step, the stirring time after adding the rubber powder to the heat-melted asphalt is preferably 10 minutes or more. This is because it takes about 10 minutes for the heat-melted asphalt and the added rubber powder to gel and be mixed uniformly. Further, the stirring speed is preferably 50 rpm to 3000 rpm. This is because a uniform asphalt rubber cannot be obtained when the stirring speed is less than 50 rpm, while the stirring effect does not change even when the stirring speed exceeds 3000 rpm. In addition, as for the temperature of the asphalt rubber at this time, 150 to 200 degreeC is preferable. If the temperature is lower than 150 ° C., the rubber powder is not sufficiently gelled. On the other hand, if the temperature exceeds 200 ° C., the asphalt is thermally deteriorated.

  In the aging step, the rubber powder added to the asphalt is gelled and uniformly mixed, and then aging is performed at a predetermined temperature and a predetermined time. The temperature at this time is preferably in the range of 150 ° C to 200 ° C. If the temperature is lower than 150 ° C., the normal melting state of the asphalt and the rubber powder cannot be maintained, and if it exceeds 200 ° C., the asphalt rubber is thermally deteriorated. Further, when the aging time is less than 30 minutes, the aging effect cannot be sufficiently obtained, and therefore, 30 minutes or more is preferable.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Example)
In carrying out the heat storage method according to the present invention, asphalt rubber was prepared according to the following procedure. Note that straight asphalt 60-80 manufactured by Shin Nippon Oil Co., Ltd. was used as asphalt, and PS- # 4000 manufactured by USS Toyo Co., Ltd., which is PS rubber powder, was used as rubber powder.

  First, straight asphalt was heated to 180 ° C. and melted. The temperature was raised to 190 ° C., and 14.5% by mass of rubber powder was added while stirring at 200 to 400 rpm using a stirrer. While maintaining the temperature at 190 ° C., the mixture was stirred for about 2 hours to prepare an asphalt rubber.

  The asphalt rubber prepared by the above procedure was heated and stored at 170 ° C., the rubber powder concentration in the asphalt rubber was measured, and the change with time of the rubber powder concentration was observed. The rubber powder concentration was measured according to the following procedure. First, about 0.2 g of asphalt rubber immediately after preparation or after a predetermined number of days was taken and wrapped in filter paper and weighed. After weighing, toluene extraction was performed with Soxhlet, followed by acetone extraction. A sample was taken out from Soxhlet and dried at room temperature or vacuum. Thereafter, the asphalt rubber was weighed, and the amount of rubber powder contained in the asphalt rubber was calculated. The obtained results are shown in FIG.

(Comparative Example 1)
An asphalt rubber was prepared in the same manner as in the example, and then heated and stored at 180 ° C., and the same evaluation as in the example was performed. The obtained results are also shown in FIG.

(Comparative Example 2)
An asphalt rubber was prepared in the same manner as in the example, and then heated and stored at 190 ° C., and the same evaluation as in the example was performed. The obtained results are also shown in FIG.

(Comparative Example 3)
After preparing an asphalt rubber in the same manner as in the examples, when it was heated and stored at a temperature lower than 150 ° C., the melted state of the rubber powder of the asphalt rubber rapidly deteriorated.

  From FIG. 1, it is possible to confirm that the rubber powder concentration decreases with time in the heat storage at 180 ° C. and 190 ° C. in Comparative Example 1 and Comparative Example 2. On the other hand, in the heat storage at 170 ° C. in the examples, the rubber powder concentration does not decrease, and it can be seen that the initial rubber powder concentration can be maintained.

It is a graph showing the time-dependent change of the rubber powder density | concentration in the different storage temperature in an Example, the comparative example 1, and the comparative example 2. FIG.

Claims (5)

  An asphalt rubber storage method comprising rubber powder in asphalt, wherein the asphalt rubber is heated and stored at 150 to 175 ° C.   The asphalt rubber storage method according to claim 1, wherein the heat storage is performed at 165 to 175 ° C.   The method for storing asphalt rubber according to claim 1 or 2, wherein the asphalt is straight asphalt.   The asphalt rubber storage method according to any one of claims 1 to 3, wherein the rubber powder is rubber powder obtained by crushing a waste tire.   The asphalt rubber is a melting step in which the asphalt is heated to melt, an addition step in which the rubber powder is added while stirring the asphalt at a melting temperature or higher after melting, and stirring that continues to be stirred while maintaining the melting temperature or higher after the addition. The asphalt rubber storage method according to any one of claims 1 to 4, wherein the asphalt rubber is produced through a step and an aging step after stirring and aging in a thermostatic bath.

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