RU2327719C1 - Bitumen-rubber composition and method of obtaining it - Google Patents

Abstract

FIELD: chemistry; obtaining bitumen-rubber compositions.

SUBSTANCE: bitumen-rubber composition consists of the following components with the given percentage mass ratios: bitumen -70-80, powder from vulcanised rubber from used motor car tyres - 15-25 and naphthalene fraction of coal resin - 5-10. The mixture of bitumen and naphthalene fraction of coal resin is heated to 100°C. The powder with particle size of 5-10 mm is then added. The components are mixed in an unsealed container at 200-220°C for 30-60 minutes. The hot mixture is then forced through a draw plate with diameter of 1 mm using a screw device. The obtained composition, which is ready for use, is poured through a metallic net into a container for storage and transportation.

EFFECT: wider assortment of bitumen-rubber compositions with better operational characteristics, simple technology of manufacturing and shortening of the process.

2 tbl, 1 ex

Description

The invention relates to the production of bitumen-rubber compositions (DBK) from bitumen and crushed vulcanized rubber from used car tires. Obtained DBK can be used in road construction as a binder for asphalt mixes, in industrial and civil construction for roofing, waterproofing, for the production of mastics and adhesives.

A well-known bitumen-rubber composition comprising bitumen and a dispersed phase, which is a rubber crumb, the surface of which by means of radical polymerization is “stitched” to unsaturated components contained in bitumen. As a result, a heterogeneous reinforcing spatial structure is formed in bitumen from the components of the composition (US Pat 2167898 C1, class C08L 95/00).

The disadvantage of this composition is that it requires the use of relatively expensive small rubber crumbs (not more than 0.5 mm), expensive initiators (peroxide compounds) and co-initiators (nitrons) of radical polymerization. In addition, the formation of a spatial grid inside the composite implies its destruction upon secondary heating upon receipt of the final asphalt material, which should adversely affect its operational properties.

Known bitumen composition, which is dissolved in bitumen devulcanized rubber, which is achieved by heating a mixture of rubber crumb, bitumen and additives of an organic base (aromatic or heteroaromatic amines, phosphines) in a sealed reactor (US Pat. Russia 2164927 C2, class C08L 95/00). The method allows to obtain a homogeneous system with a low temperature of brittleness, however, the particle sizes of the rubber crumb to be dissolved are not indicated, which involves the use of very finely ground (therefore, expensive) rubber crumb. In addition, the use of a sealed reactor implies operation with excess pressure and the discontinuity of the process for producing a bitumen-rubber composite.

The closest composition to the invention and the method for its preparation is the composition obtained in accordance with patent 2162475 C2, class. С08L 95/00 (Russia). According to this method, a bitumen composition containing bitumen and rubber dissociated to a lack of distinguishable particles is obtained by thermally and mechanically acting on a mixture of bitumen, hydrocarbon oil, liquid rubber and crumb rubber. The disadvantages of this composition and its production method is a long and complex process of multiple loading and heating with vigorous stirring, the use of expensive reagents - aromatic oils with the trade names "SUNTEH" and "HYDROENE", low molecular weight liquid rubber (polybutadiene or polyisoprene with a molecular weight of 300- 60,000). In addition, it is not indicated what operational properties a bitumen-rubber composite has.

The objective of the invention is to expand the range of bitumen-rubber compositions with improved performance while simplifying the technology of preparation of the composition by reducing the number of stages and reducing the duration of the process, making it possible to conduct the process of preparing DBK in a continuous mode and the absence of expensive ingredients in their preparation.

This object is achieved by the fact that the inventive bitumen-rubber composition includes bitumen (70-80%), crushed vulcanized rubber from used car tires (15-25%) and a naphthalene fraction of coal tar (5-10%). In addition, the problem is solved by the fact that the proposed method for producing DBK is that the components are mixed in an unpressurized container at a temperature of 200-220 ° C for 30-60 minutes, and then the mixture is pressed in the hot state using a screw device through a die 1 mm. The resulting ready-to-use DBK is poured through a metal mesh into a container for storage and transportation.

Under these conditions, due to the destruction of the network of transverse sulfide and polysulfide bonds in the rubber, a homogeneous mass is obtained without the presence of distinguishable particles of rubber containing undeformed polymer rubber chains. The final product differs from the original bitumen in improved characteristics, namely, lower brittleness temperature, increased softening temperature, greater elasticity, which is typical for bitumen-polymer binder composite materials.

To prepare the composition, road bitumen of the BND 60/90 or 90/130 brand is used in accordance with GOST GOST 22245-90, a naphthalene fraction of coal tar that does not contain components with a boiling point below 200 ° C according to TU 14-7-100-80. The concentration range of the coal tar content in the composite is determined by the optimal ratio of the accelerating effect of the resin on the dissolution of rubber in bitumen and the operational characteristics of the final product.

Rubber crumb (5-10 mm) can be prepared by grinding shock-absorbed car tires both without cord and with synthetic cord. The lower limit of the content of rubber crumb is due to a noticeable change in the properties of the final product compared to the original bitumen, and the upper limit is limited by the negative effect of dispersed soot released during the dissolution of the rubber crumb.

The indicated limits of the temperature regime of heating the composition are optimal, because below 200 ° C, the dissolution of rubber occurs very slowly, and above 220 ° C, it is impractical to increase the temperature, because processes of destruction of rubber macromolecules are underway. Subject to the specified temperature conditions, the amortized rubber passes into the bitumen solution in the form of unvulcanized rubber with a high molecular weight, which ensures an improvement in the performance properties of the composite compared to the original bitumen.

Table 1 shows the compositions of the initial mixture, temperature conditions and the duration of the preparation of the composite, and in table 2 the physical and mechanical properties of the resulting composites.

Example 3

In a 2-liter beaker equipped with a heating jacket and a mechanical paddle mixer, 500 g of BND 60/90 grade bitumen, 70 g of coal tar naphthalene fraction are placed and the mixture is heated to 100 ° C. Then, 140 g of vulcanized rubber crumb from used car tires with a particle size of 5-10 mm are filled up. The resulting mass is heated with stirring to 220 ° C for 60 minutes and pressed hot using a screw device through dies with a diameter of 1 mm.

The method according to the invention is simple in execution, allows to obtain bitumen-rubber compositions that exceed the original bitumen in its characteristics. The softening temperature increased by 12–20 ° С, the fragility temperature, on the contrary, decreased by 10–22 ° С, elasticity appeared at normal temperature (25 ° С), typical for polymer-bitumen binders, and at a lower temperature (0 ° С) the brittle gap characteristic of bitumen is completely absent. Adhesion to marble chips and sand increased significantly. The short duration of the process of transferring rubber crumbs into a dissolved state allows to reduce the energy consumption for the production of bitumen-rubber composite in comparison with known methods. The present invention is one of the effective approaches for the disposal of amortized rubber products and waste products.

Table 1 Composition, temperature and time regime for the preparation of a bitumen-rubber composition Sample No. Composition, wt.% DBK preparation temperature, ° С Mixing time min 1 (test case) Bitumen - 70; rubber crumb - 10; coal tar - 20 220 40 2 (test case) Bitumen - 60; rubber crumb - 30; coal tar - 10 220 40 3 Bitumen - 70; rubber crumb - 20; coal tar - 10 220 40 four Bitumen - 75; rubber crumb - 20; coal tar - 5 220 60 5 Bitumen - 70; rubber crumb - 20; coal tar - 10 200 60 6 (test case) Bitumen - 70; rubber crumb - 20; coal tar - 10 240 40 7 Bitumen - 70; rubber crumb - 20; coal tar - 10 220 60 8 Bitumen - 70; rubber crumb - 20; coal tar - 10 220 thirty

table 2 The test results of some samples of bitumen-rubber composition Sample No. Penetration at 25 ° C Softening point, ° С Fragility temperature, ° С Elasticity at 25 ° С,% Change in softening temperature after heating, ° C Marble or sand grip Flash point, ° С one 70 49 -25 40 5 Stand according to the control sample No. 2 GOST 11508-74 220 2 41 70 -13 34 four 3 65 67 -39 85 6 four 68 59 -27 80 6 5 58 61 -33 61 5 6 90 55 -21 39 3 7 72 67 -38 84.5 5 8 63.5 63 -26 75 5 BND 60/90 80.5 47 -17 Not standardized 5 Not withstand 230

Claims (2)

1. Bitumen-rubber composition, including bitumen and crumb from vulcanized rubber from used car tires, characterized in that the specified crumb of vulcanized rubber has a size of 5-10 mm and the composition further comprises a naphthalene fraction of coal tar in the following ratio, wt.%: bitumen 70-80 specified vulcanized rubber crumb 15-25 coal naphthalene fraction 5-10 2. A method of obtaining a bitumen-rubber composition, comprising heating a mixture of bitumen and a naphthalene fraction of coal tar to 100 ° C, then a crumb of vulcanized rubber is introduced from used car tires with rubber particle sizes of 5-10 mm, mixed at 200-220 ° C for 30 -60 min and in a hot state they are forced through a screw device through dies with a diameter of 1 mm in the following ratio of components, wt.%: bitumen 70-80 vulcanized rubber crumb 15-25 coal naphthalene fraction 5-10