RU2131441C1 - Method of preparing rubber solution for road building - Google Patents

Abstract

FIELD: road building. SUBSTANCE: method comprises dissolving rubber crumb in admixture with shale oil and kerosene. Kerosene is introduced into stirred reactor, the whole is heated to 70-80 C, rubber crumb with fraction size of not greater than 10 mm is added, the resulting mixture is maintained for 3 or 4 hours to make rubber swollen, and shale oil is then added, and the whole is stirred at above-mentioned temperature to form homogeneous solution. EFFECT: simplified technology, reduced power consumption of production process. 2 cl, 2 dwg, 1 ex, 1 tbl

Description

 The invention relates to road construction to a method for the preparation of organic binders and can be used in the building materials industry. In road construction, methods for modifying bitumen with rubber, copolymers, latexes, monomers are known.

 Methods of compounding bitumen with rubbers and copolymers are very laborious, require special equipment. The effectiveness of the method of combining bitumen with latex is small due to the coagulation of rubber macromolecules under the influence of high temperatures. The process of polymerization of monomers in bitumen requires special reagents, a strictly defined temperature and appropriate equipment.

 Common disadvantages of these methods for modifying bitumen with polymers are heterogeneity of binders, increased polymer consumption to achieve the desired effect. These disadvantages will be eliminated by combining bitumen with rubber solutions.

 Rubber is dissolved in the waste from the production of synthetic rubber plants, for example, in still bottoms of the toluene fraction at a ratio of 1-4-12.

The rubber solution is fed into bitumen, followed by partial removal of the solvent at 180 ^{° C.} in homogenizing plants.

 It is possible to introduce a softener and a filler into a bitumen-rubber binder at a temperature above the boiling point of the solvent.

 It is proposed to use petroleum raw materials for the production of viscous bitumen (tar) or industrial oil as a solvent for divinylstyrene thermoplastic elastoplast (Automobile Roads, M., 1995, N12).

 The disadvantages of the considered methods of obtaining solutions of rubbers (polymers) for the preparation of bitumen-rubber binders are a decrease in heat resistance due to the presence of a thinner, significant labor and energy costs, insufficient adhesion to mineral materials.

 Closest to the proposed solution is a method for producing a rubber solution in the form of its 12-15% solution in shale oil and bottoms of pyrolysis resins (USSR copyright certificate 1671671 A, 1991).

The dissolution of rubber with a size of 5 - 15 mm is carried out in a laboratory type stirrer. The temperature of the solvent is 60 ^o C. The ratio of shale oil and bottoms of pyrolysis resins (0.5 - 0.6): (0.5 - 0.4) is taken from the solubility condition and the maximum use of shale oil.

 The process according to the above method of preparing a solution of rubbers is very complicated, because It requires sealed equipment, a refrigerator and a condensate collection tank. This is due to the fact that the composition of the bottoms of pyrolysis resins includes benzene, toluene, xylene, ethyl toluene, m-styrene and other components characterized by carcinogenic and toxic properties.

 Similar problems arise when combining a solution of rubber in shale oil and bottoms of pyrolysis resins with bitumen.

 The aim of the invention is to simplify the technology, improve the environmental situation when preparing the rubber solution, reduce the energy intensity of the process.

The goal is achieved in that in the method of preparing a rubber solution for road construction, kerosene and shale oil are used as a rubber solvent in the ratio (0.2 - 0.3): (0.8 - 0.7), and the rubber is dissolved in the following sequence. The calculated quantity of kerosene heated to 70 - 80 ^° C is placed in the mixer. Then, the required amount of crushed rubber (fraction 0 - 10 mm) is fed into kerosene and it remains in it for 3 to 4 hours. Then, shale oil is fed into the mixer based on obtaining a 12 - 15% solution. After shale oil is fed into the reactor, the agitator is switched on. The operating time of the mixer is determined by the uniformity of the resulting solution.

A comparable analysis with the prototype shows that the inventive method for preparing a solution of rubbers differs from the prototype in that kerosene and shale oil are used as a solvent in the ratio (0.2 - 0.3): (0.8 - 0.7), the temperature range 70 - 80 ^o With and the sequence of the dissolution process, crumb rubber is fed into kerosene, after rubber swelling for 3 to 4 hours, shale oil is fed with subsequent mixing of the components until a homogeneous solution is obtained.

In the technology for preparing the rubber solution, there is no known method in which kerosene and shale oil are used as the rubber solvent in the ratio (0.2 - 0.3): (0.8 - 0.7), and the sequence of the dissolution process; kerosene is fed into the reactor (mixer) and heated to 70 - 80 ^o C. Then, crumb rubber fr. is introduced into the heated kerosene. 0 - 10 mm and maintained in it for 3 to 4 hours. After the rubber swells, shale oil is fed, followed by mixing of the components until a homogeneous solution is obtained. Throughout the entire period of mixing maintained at a temperature of 70 - 80 ^o C.

 Therefore, the proposed essential features meet the criterion of "significant differences".

 The invention is illustrated by drawings.

 In FIG. 1 shows the dependence of the time of mixing (dissolution) of rubber on the ratio of kerosene and shale oil.

 Figure 2 presents the dependence of the time of dissolution of the rubber on the heating temperature of the components.

 An example implementation of the method. For research, commodity rubbers SKD (butadiene), SCS (styrene) produced by the Voronezh plant were adopted. As solvents - shale oil C - 1 manufactured by the Shale Oil Refinery, which meets the requirements of TU 38.10957.80, kerosene according to GOST 18499-73. The named rubbers in shale oil dissolve only at low concentrations, 5-7%. Such solutions have a negligible effect on the properties of bitumen-rubber binders.

 In order to increase the concentration of rubber in the solvent, kerosene was adopted. Rubbers are highly soluble in kerosene.

 In the study and selection of rubber solutions, the minimal use of kerosene was taken into account, so that the amount of evaporated products was also minimal, and the dissolution time.

The dissolution of rubber with a size of 0 - 10 mm was carried out in a laboratory mixer of a frame type with a capacity of 4 l. The dissolution temperature was adopted in the range of 50 - 100 ^o C.

 Solubility was characterized visually by the absence of insoluble pieces of rubber on a glass rod and the homogeneity of the solution.

 The dependence of the time of mixing (dissolution) of rubber on the ratio of kerosene and shale oil is presented in figure 1.

 From the presented data it is seen that with a ratio of kerosene - shale oil of 0.2: 0.8, the dissolution time is 23 hours. A further decrease in kerosene leads to a sharp increase in the time of dissolution of rubber. It was not possible to obtain a homogeneous solution. An increase in kerosene content of more than 30% by weight of the solvent does not lead to a significant reduction in the dissolution time, and the amount of kerosene to be distilled off during the preparation of bitumen-rubber binder increases, which leads to a rise in the cost of production.

 Thus, the recommended ratio of kerosene to shale oil (0.2 - 0.3): (0.8 - 0.7) is taken from the solubility of rubber, the maximum use of shale oil and economic efficiency.

 The requirements for rubber solutions are listed in the table.

The maximum concentration of the solution (conditional viscosity, C ₅ ⁶⁰ = 1000 s) of rubber is taken from the condition that the bitumen pump can work. Higher concentration will not allow to drain from the tank and pump the above solution.

The minimum concentration (conditional viscosity, C ₅ ⁶⁰ = 700) is taken from the conditions for obtaining the necessary qualitative effect from the modification of bitumen and economic considerations.

In FIG. 2 shows the dependence of the dissolution time of rubber in a solvent on the heating temperature of the composition. Curves 1, 2, 3 characterize the ratio of kerosene and shale oil, as 0.25, 0.33 and 0.42. Dissolution time depends on temperature and on the ratio of kerosene - shale oil. From the above data it follows that the optimum dissolution temperature is the limit of 70 - 80 ^o C. At temperatures less than 70 ^o With the dissolution time increases sharply, which reduces the productivity of the installation and increases the cost of production.

At temperatures above 80 ^o With the dissolution time decreases, but slightly. The gain in time does not compensate for the cost of heating the composition more than 80 ^o C.

 The proposed method is tested under production conditions in the village. Latne of the Voronezh region.

 The proposed method allowed to simplify the technology of preparation of the rubber solution; improve sanitary and hygienic conditions in the workplace; refuse to use carcinogenic and toxic material; reduce energy costs.

 Thus, the proposed method for producing a bitumen-rubber binder simplifies the technology, increases the productivity of the installation for the preparation of a solution of rubber, improves sanitary conditions, in addition, it became possible to abandon the use of a carcinogenic and toxic solvent.

Claims (2)

1. A method of preparing a rubber solution for road construction, comprising dissolving the rubber crumb in a mixture of shale oil and a solvent at an elevated temperature, characterized in that kerosene is used as a solvent, while the preparation of a rubber solution is carried out in the following sequence: kerosene is fed into the reactor with a stirrer , heated to 70 - 80 ^o C, injected with fractions of rubber crumb size of not more than 10 mm, the resulting mixture was allowed to stand for 3 - 4 hours to swell rubber, and then fed shale m layer, followed by blending the components until a homogeneous solution at the same temperature.  2. The method according to claim 1, characterized in that the rubber is dissolved in a mixture of kerosene and shale oil, taken in a mass ratio of (0.2 - 0.3): (0.8 - 0.7), respectively.

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