JP2009209196A - Method of producing asphalt rubber - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method of producing asphalt rubber to restrain scattering of viscosity in early stages of binder production. <P>SOLUTION: This method of producing asphalt rubber includes a melting process to heat and melt asphalt, an addition process to add rubber powder while agitating the asphalt after melting at the melting point or higher, and an agitating process to continue agitating while maintaining the melting point or higher after adding. In the addition process and the agitating process, the temperature of the asphalt rubber is set to be higher than the temperature in the melting process, preferably 185-200°C. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a method for producing an asphalt rubber, and more particularly, to a method for producing an asphalt rubber that suppresses the decomposition of rubber powder during the production of the asphalt rubber and suppresses viscosity variation at the initial stage of asphalt rubber production.

  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 an asphalt rubber is produced by adding a predetermined amount of waste tire rubber powder to heat-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.)

  However, in this asphalt rubber manufacturing method, the rubber powder swells and decomposes. For this reason, there is a problem that the viscosity of the asphalt rubber is likely to vary at the initial stage of manufacturing.

  Accordingly, an object of the present invention is to provide a method for producing an asphalt rubber that suppresses the decomposition of the rubber powder during the production of the asphalt rubber and suppresses the viscosity variation at the initial stage of the production of the asphalt rubber.

  As a result of intensive studies, the present inventors have found that asphalt rubber viscosity is stabilized immediately after production by increasing the temperature during production of asphalt rubber to complete the present invention.

  That is, the asphalt rubber manufacturing method of the present invention includes a melting step of heating and melting asphalt, an addition step of adding rubber powder while stirring the asphalt at a melting temperature or higher after melting, and a melting temperature higher than the melting temperature after the addition. And a stirring step of continuing stirring while maintaining the temperature of the asphalt rubber at a temperature higher than the temperature of the melting step in the addition step and the stirring step. Is.

  Moreover, in this invention, it is preferable to make the temperature of the asphalt rubber in the said addition process and the said stirring process into the range of 185-200 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 waste tire is more preferably a passenger tire waste tire.

  According to the present invention, by adopting the above-described configuration, it is possible to suppress variations in viscosity due to swelling and decomposition of rubber powder during production of asphalt rubber, and asphalt rubber having a stable viscosity immediately after production is obtained. Can be obtained. In addition, since the aging step that has been conventionally required can be omitted, the workability can be improved.

Hereinafter, preferred embodiments of the present invention will be described in detail.
A melting step of heating and melting asphalt, an addition step of adding rubber powder while stirring the asphalt at a melting temperature or higher after melting, and a stirring step of continuing stirring while maintaining the melting temperature or higher after the addition In the asphalt rubber manufacturing method, it is important that the temperature of the asphalt rubber is higher than the temperature of the melting step in the addition step and the stirring step.

  In the present invention, the temperature of the asphalt rubber is preferably in the range of 185 to 200 ° C. during the addition step and the stirring step. If the heating temperature is less than 185 ° C., the rubber powder gradually swells, so the initial viscosity is not stable. On the other hand, when it exceeds 200 ° C., the asphalt is likely to be thermally deteriorated, and the rubber powder is decomposed, so that the viscosity of the asphalt rubber at the initial stage of manufacture becomes unstable.

  In the addition process, the rubber powder may be added 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 while adding. 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 of the added rubber powder 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 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.

  Examples of the asphalt rubber that can be suitably used in the present invention include 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.

  The rubber powder in the asphalt rubber that can be used in the present invention is not particularly limited, but is preferably rubber powder obtained by pulverizing waste tires. 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 the present invention, the rubber powder may be PS rubber powder. More preferred. 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 has additives such as color pigments, UV absorbers, antioxidants, adhesion improvers, anti-aging agents, metal deactivators, light stabilizers, foaming agents, and water removal agents as necessary. Further, it may be blended with a diluent solvent, a polymer for adjusting physical properties or a low molecular additive.

Hereinafter, the present invention will be described in more detail with reference to examples.
(Example)
The manufacturing method of the asphalt rubber according to the present invention was carried out according to the following procedure to prepare an asphalt rubber. Straight asphalt 60-80 manufactured by Cosmo Oil Co., Ltd. was used as the asphalt, and PS- # 4000 manufactured by USS Toyo Co., Ltd., which is PS rubber powder, was used as the rubber powder.

  First, straight asphalt was heated and melted to 180 ° C. using a mantle heater (manufactured by Otsuka Electric Co., Ltd.). Then, it heated at 190 degreeC and 14.5 mass% rubber powder was added, stirring at 200-400 rpm using a stirrer. Thereafter, the mixture was stirred for 3 hours while maintaining at 190 ° C. to prepare an asphalt rubber.

  The asphalt rubber prepared by the above procedure was heated and stored at 170 ° C., and the viscosity of the asphalt rubber at 180 ° C. was measured after a predetermined number of days. For viscosity measurement, Viscotester VT-04F manufactured by Lion was used. The time immediately after the addition of rubber powder was defined as 0 hour. The obtained results are shown in FIG.

(Comparative example)
A comparative asphalt rubber was prepared by the same procedure as in the above example except that the stirring and mixing temperature was 170 ° C., and the viscosity was measured by the same procedure as in the example. The obtained results are also shown in FIG.

  From FIG. 1, the asphalt rubber (comparative example) prepared at 170 ° C. with stirring and mixing temperature takes about 2 days after preparation until the viscosity becomes stable, whereas the asphalt rubber (example) which was stirred and mixed at 190 ° C. ) Confirms that the viscosity is stable immediately after preparation. Therefore, the asphalt rubber produced by the production method of the present invention can be used with a stable viscosity immediately after production.

It is a graph showing the time-dependent change of the viscosity of the asphalt rubber of an Example and a comparative example.

Claims (4)

  A melting step of heating and melting asphalt, an addition step of adding rubber powder while stirring the asphalt at a melting temperature or higher after melting, and a stirring step of continuing stirring while maintaining the melting temperature or higher after the addition In the asphalt rubber manufacturing method, the temperature of the asphalt rubber is higher than the temperature of the melting step in the adding step and the stirring step.   The manufacturing method of the asphalt rubber of Claim 1 which performs the said addition process and the said stirring process at 185-200 degreeC.   The method for producing an asphalt rubber according to claim 1 or 2, wherein the asphalt is straight asphalt.   The method for producing an asphalt rubber according to any one of claims 1 to 3, wherein the rubber powder is rubber powder obtained by crushing a waste tire.

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