Demand for adhesives and sealants continues unabated, even with the advent of more and more advanced composites and pipe spot welding technologies. It is obvious that traditional means of sealing assembly joints, like flax and FUM tape, have long ceased to compete with adhesive sealants. The most technologically advanced representative of this area is anaerobic glue, which is used by both professionals and home craftsmen.
Material overview
The tool is a special kind of adhesive materials that act as seals and sealants. Such compositions are called anaerobic due to the lack of an oxygen environment in the zone of action. At the time of application of such an adhesive to the target surface, a rapid flow of air occurs with the creation of an oxygen-free atmosphere, resulting in favorable conditions for curing.material. Physically and chemically, anaerobic adhesive can be thought of as a polymeric liquid mixture that comes in the form of a paste, gel, or even an aerosol.
Material Applications
This kind of compounds are used in a variety of industries - from household to aerospace. By the way, in Russia, the spread of anaerobic products is associated with the active development of rocket and space equipment in the middle of the last century. At first they were used to lock threaded elements in order to prevent arbitrary loosening of nuts. It is in this capacity that this material is used today. Moreover, the anaerobic thread sealant on the market forms the basis of pipe seals. It is also used to eliminate minor defects on the surface of sheet metal, to strengthen welds and fix various joints. Directly in the form of glue, this agent is recommended to be used for flat surfaces. In industry, the material helps to modify the characteristics and structural qualities of powder metallurgy products.
Glue composition
Most anaerobic materials are based on the following ingredients:
- Acrylic oligomers and monomers.
- Substances that initiate adhesive activity.
- Inhibitors (stabilizing group).
- Functional inclusions. The use of components of this spectrum is individual and depends on the formulation of a particular manufacturer. In particular,dyes, plasticizers, thickeners, frost-resistant additives, etc. can be used.
Inhibitors and activators of anaerobic glue, which determine the functional qualities of the composition, deserve special attention. The initiators are understood as hydroperoxide, which determines the processes of free-radical polymerization. In combination with reaction accelerators (amines and heterocyclic nitrogen-containing compounds), it provides a decrease in the polymerization temperature. As for activators, their main task is to accelerate curing. This category of components is represented by copper s alts, organic solutions and sulfur-nitrogen-containing compounds.
Operation principle
The acrylic group has the main sealing and adhesive effect, forming spatially cross-linked polymer structures. The interaction of substances of the initiating group with the metal structure promotes the formation of radicals, due to which oxygen is consumed. Against this background, the curing process is enhanced. It is important to emphasize that the metal as such is a necessary participant in the polymerization process, due to which the anaerobic composition of the thread sealant passes from the liquid state into the structure of a solid polymer. Another thing is that different metals, due to the peculiarities of their own molecular structure, can interact differently with the same activators. For example, iron, copper and steel contribute to the acceleration of polymerization (solidification), as they participate in redox reactions. As a result, blanksof these metals are sealed 2-3 hours after applying the composition. In the case of aluminum, chromium and alloyed steel alloys, the curing process to the required state can take 5-7 hours. But the manufacturers themselves, regardless of the target material, recommend introducing the machined part into the operational process only after 24 hours.
Performance
Anaerobic sealing materials are characterized by the following features:
- Combination of viscosity and fluidity within limits to work with clearances from 0.07 to 0.5 mm.
- Durability - maintaining basic characteristics for at least 12 months.
- High curing rate at room temperature.
- Single-component - the composition is sold ready-made, so it does not need to be diluted with special additives.
- Strength properties - best seen in a fixative adhesive suitable for repairing metal, enamel, ceramic and graphite materials.
- Anti-corrosion - especially beneficial for metal products, the threaded sections of which do not have their own rust protection.
- Resistant to oily substances, thanks to which the compound can be applied to new surfaces of new pipes with factory lubrication.
Varieties of glue
Despite the common technological basis and similar component content, anaerobic compositions due to modifiers get differentsets of technical and physical properties, which leads to their division into the following types:
- Sleeve retainers. Designed for maintenance of mechanical parts of various machinery - for example, bearings, gears, bushings, spindles, cylinders, etc. Such compounds demonstrate high load-bearing capacity for cylindrical fasteners, reducing stress during operation of the elements.
- Plumbing sealants replacing traditional PTFE pastes and tapes. They are used as pipe and threaded seals. Among the operational features, one can single out a quick polymerization effect, the absence of evaporation and melting at high temperatures, as well as providing a lubricating effect in some formulations.
- Control adhesive mixtures. They are used in industry - in particular in the automotive and mechanical engineering in assembly processes and in maintenance. During operation, gaps in threaded connections are filled, reducing vibration effects.
Technology of product application
Before use, the product must be shaken in the package, clean the work surface and prepare a clean rag or napkin to remove excess glue. The composition is applied to the working area in a thick layer so that the entire joint area is covered. In the case of a threaded fastening for pipes, the sealant is placed both outside and inside the workpieces along a helical ditch. Further, the composition is evenly distributed, and then the connection is made. Surplusmust be disposed of immediately by carefully cleaning contaminated surfaces.
Optimal working conditions
In order to maximize the use of the properties of anaerobic material, it is desirable to think over in advance the favorable conditions for its operation. So, temperature is a serious factor - such products show themselves best at 18-30 ° C. It is desirable to prevent contact of the treated surface with aggressive media such as acids, solvents and alkalis, which will corrode the structure of the polymer fabric. Many anaerobic adhesive formulations are sensitive to mechanical stress, and this also applies to small vibrations. Therefore, it is recommended to securely fix pipes and other structures, preventing even the slightest vibration.
Conclusion
From the point of view of efficiency, the anaerobic sealing principle for various types of threaded fasteners is optimal. It has practically no negative operational factors, if you do not take into account the complexity of dismantling. It will be necessary to disassemble structures treated with anaerobic adhesive-sealant with the connection of a building hair dryer, the hot streams of which will destroy the polymer structure. Also, when choosing this method of sealing joints, one should keep in mind the financial aspect. So, on average, for 50 ml of anaerobic composition, manufacturers ask for 400-500 rubles. In comparison, traditional sealing and sealing products will cost several times less, which is especially noticeable with regular maintenance of threaded connections.in large volumes.
