Mastic BPM-3 and BPM-4. Compound properties
Content
Properties and positive features of rubber-bitumen mastics
Mastic, prepared on the basis of rubber and bitumen, is a one-component coating, which is an insurmountable barrier to moisture. It forms a continuous layer in which, despite external temperature fluctuations, a stable thermal regime is maintained, which significantly slows down the processes of corrosion and decay of metal materials.
Rubber-bitumen mastics belong to the group of so-called "cold" mastics, which are applied to the sealed parts of the car after preheating, but at room temperatures (heating is only intended to slightly reduce the viscosity of the composition, for ease of working with it). In addition, each of the components performs strictly defined functions. Rubber increases the elasticity of the mastic and its resistance to bending during sharp blows or shocks, and bitumen contributes to the hydrophobicity of the mastic and its resistance to chemically aggressive environments (acids and alkalis).
Since any bituminous base ages over time and loses its elasticity, polymeric compounds are added to the mastic, which increase the softening point. This is necessary in order to use BPM series rubber-bitumen mastics all year round.
Operational characteristics of the compositions under consideration:
| Mastic brand | Softening point, ° C | Elongation plasticity, mm | Relative elongation at the start of cracking, % | Application temperature, °С |
| BPM-3 | 50 | 3 ... 5 | 60 | 10 ... 30 |
| BPM-4 | 60 | 4 ... 8 | 100 | 5 ... 30 |
Mastic BPM-3
Mastic BPM-3When applied to metal surfaces of a car, the composition performs the following functions:
- Protects steel from corrosion.
- Reduces the noise level in the cabin.
- Performs mechanical protection of the bottom from various salts, crushed stone, gravel.
- Helps dampen vibrations.
The presence of fine rubber in the composition ensures sufficient elasticity of the coating, which is maintained even at low temperatures (up to -15 ... -200FROM).
Aluminosilicate compositions are introduced into the BPM-3 mastic, the presence of which protects the external body parts from dynamic loads. At the same time, mechanical wear resistance is improved. The bituminous component contributes to the necessary continuity of the coating and minimizes the area of free areas.
Mastic is flammable, so it is recommended to work with it in well-ventilated areas, away from sources of open flame. Before applying the mastic is heated in a water bath or in a warm room. The composition is ready for use when it is a homogeneous viscous sticky mass of black color.
Mastic BPM-4
BPM-4 is an improved formula of BPM-3 mastic. In particular, there are components that increase the modulus of elasticity of the material, which has a positive effect on the durability of the coating.
In addition, BPM-4 rubber-bitumen mastic is characterized by:
- The presence of amine-containing petroleum oils, which give an additional anti-corrosion effect that lasts for a long period of time.
- Increased elasticity of the treated surface, which is especially important for vehicles operated on bad roads.
- Increased environmental friendliness during use, since it does not contain components that irritate the respiratory system.
The remaining operational parameters correspond to the capabilities of the BPM-3 mastic.
The production of rubber-bitumen mastics grades BPM-3 and BPM-4 is carried out in accordance with the technical requirements of GOST 30693-2000.
User Reviews
Most reviews indicate the following features of the use of these types of mastics:
- The desirability of using thinners, since in the initial state (even after thermal softening) it is difficult to use mastics, especially on surfaces with a complex configuration. Gasoline Kalosh, kerosene, toluene are recommended as diluting compounds. However, the total amount of thinner should not exceed 15% of the original mastic volume.
- Some reviews note the fact of physical aging of the coating treated with BPM-3, which car owners are struggling with by introducing plasticizers into the mastic. In this capacity, you can use filtered engine oil.
- Compared to BPM-3, BPM-4 mastic can be applied in one layer, but before that it is recommended to thoroughly clean and degrease the surface, as well as apply a phosphate-containing primer.
- Unlike some similar products - for example, Kordon anticorrosive - Nizhny Novgorod mastics do not crack at low ambient temperatures.
Users also consider the “friendliness” of both compositions to be a positive feature, which allows the use of other brands of similar products.
