Why are Antioxidant Additives needed? Operating principle, main types and industrial applications
2026-11-05
Antioxidant additives- important functional components of lubricant formulations. Their main task is to slow down the oxidation of base oil and other components, reduce the formation of acid compounds, sludge and oxidation products. At high temperatures, increased loads and long-term operation, the oil gradually reacts with oxygen, which can lead to a change in viscosity, an increase in acid number and deterioration in performance characteristics. Correctly selectedAntioxidant additivesincrease the thermal-oxidative stability of the oil and help extend its service life.
For lubricant manufacturers, the choice of antioxidant additives is important not only from the point of view of oxidation stability. It also affects the stability of the formulation, the compatibility of various components and the performance properties of the finished product. Therefore, understanding the chemical types, mechanisms of action and application featuresAntioxidant additivesimportant in the development of high-performance lubricants.
1. What are antioxidant additives for lubricants and what problems do they solve?
During storage and operation, lubricants are exposed to oxygen, high temperature, metal surfaces and other factors that promote oxidation.
As oxidative processes develop, base oil molecules change their structure. In this case, peroxides, acid compounds and other oxidation products are formed. Their accumulation can lead to the following problems:
- Viscosity change.Further reactions of oxidation products can lead to the formation of larger molecular structures and increased oil viscosity.
- Increase in acid number.Acid compounds formed during the oxidation process increase the acid number and can increase the risk of corrosion of metal parts.
- Formation of sludge and deposits.Some oxidation products can combine and form sludge, varnish deposits and other contaminants.
- Deterioration of lubricating properties.Oxidation of the base oil and consumption of functional additives can adversely affect the overall performance of the lubricant.
The main function of antioxidant additives is to slow down oil oxidation by suppressing chain reactions or decomposition of peroxides formed during the oxidation process.
Unlike filters, which remove contaminants from the oil, antioxidant additives act directly on the chemical processes of oxidation. However, they do not replace detergents, dispersants and other functional additives that perform their own tasks as part of the formulation.
From a lubricant development perspective, antioxidant additives help solve three main problems:
1. Slowing down the oxidation of base oil
Antioxidant additives suppress chain reactions involving free radicals and slow down the oxidation of base oils at elevated temperatures.
2. Reduced accumulation of oxidation products
By scavenging free radicals or decomposing peroxides, antioxidant additives help reduce the formation and accumulation of certain oxidation products, control the rise in acid number and control the formation of deposits.
3. Increasing the thermal-oxidative stability of the oil
At high temperatures and long-term operation, the correct combination of antioxidant additives helps maintain stable oil characteristics and meet the requirements of various types of industrial equipment.
Thus, antioxidant additives are important components of the formulations of motor, industrial transmission, hydraulic and turbine oils, as well as other lubricants.
2. Operating principle and main advantages Antioxidant additives
Oxidation of lubricants usually occurs through the mechanism of chain free radical reactions, including the stages of initiation, development and chain termination.
Under the influence of oxygen and high temperature, free radicals can form in base oil molecules. By interacting with oxygen, they turn into peroxide radicals, which then react with other oil molecules. As a result, new free radicals are formed, supporting the further development of the oxidative process.
Antioxidant additives affect these processes through various chemical mechanisms.
| Mechanism of action | Basic reaction principle | Implications for oil formulation |
| Free radical binding | Reaction with peroxide and other active radicals, interrupting the chain oxidation process | Slows down base oil oxidation |
| Peroxide decomposition | Converts hydroperoxides into more stable compounds, reducing the likelihood of further initiation of oxidation | Reducing the risk of developing oxidative reactions |
| Synergistic effect | Combined use of different types of antioxidant additives with complementary mechanisms of action | Improving the overall antioxidant effectiveness of the formulation |
When developing formulations, the correct use of antioxidant additives provides the following benefits:
1. Extending lubricant life
Anti-oxidation additives slow down the oxidation of the base oil and help maintain its performance characteristics over the specified period of use.
2. Control of acid number growth
Suppressing oxidative reactions reduces the formation of some acidic products and helps control changes in oil acid number.
3. Reduced formation of sludge and oxidative deposits
Reducing the amount of oxidation products and their further accumulation helps control the formation of sludge, varnish films and other deposits.
4. Increased stability at high temperatures
In motor, turbine and industrial oils, antioxidant additives help increase the product's resistance to thermal and oxidative stress.
Please note that the actual effectiveness of antioxidant additives depends on the type of base oil, chemical structure of the additive, input concentration, compatibility with other components and operating conditions. Therefore, it is incorrect to evaluate the characteristics of the finished product based on only one component.
3. Main chemical types Anti-oxidation additives for lubricants
Based on their chemical structure and mechanism of action, antioxidant additives for lubricants are divided into phenolic, aromatic amine and peroxide decomposing additives, as well as other functional components.
Different types of antioxidant additives have their own characteristics of reactivity and areas of application. When choosing, the properties of the base oil and the requirements for the finished product are usually taken into account.
| Additive type | Main structural features | Mechanism of action and scope of application |
| Antioxidant additives based on hindered phenols | Contains a hindered phenolic hydroxyl group | Bind free radicals through the transfer of a hydrogen atom; used to protect lubricants and other organic products from oxidation |
| Antioxidant additives based on aromatic amines | Typically contain aromatic amine groups | They have the ability to bind free radicals; used in systems that place increased demands on thermal-oxidative stability |
| Thiodiester additives | Contain thioether structural fragments | Participate in the decomposition of hydroperoxides and are often used as auxiliary antioxidant components |
| Phosphite additives | Contains trivalent phosphorus | Promote the decomposition of hydroperoxides and can be used in combination with other antioxidant additives |
| Multifunctional antioxidant components | Possess antioxidant and other functional properties | Depending on the chemical composition, they can combine antioxidant, antiwear and other types of action |
Phenolic and aromatic amine components are generally classified as chain-breaking antioxidants. Some phosphorus- and sulfur-containing components are predominantly involved in the decomposition of hydroperoxides.
In finished lubricant formulations, different types of antioxidant additives can be used separately or in combination. The choice depends on the product requirements and the results of compatibility and effectiveness tests.
4. Classification Antioxidant additives and main representatives
Taking into account the chemical structure and area of application, antioxidant additives can be divided into several main groups.
1. Antioxidant additives based on hindered phenols
Phenolic antioxidant additives suppress oxidation chain reactions by binding free radicals.
Their main features:
- They transfer the hydrogen atom to free radicals, helping to break chain reactions.
- Used in various systems based on base oils.
- Can be used in conjunction with other types of antioxidant additives.
2. Antioxidant additives based on aromatic amines
Aromatic amine antioxidant additives have a high free radical scavenging ability and are important for lubricants operating at elevated temperatures.
Main features:
- Participate in free radical chain termination reactions.
- Used in some lubricant systems operating at high temperatures.
- Can be combined with phenolic antioxidant additives to optimize overall antioxidant effectiveness.
3. Phosphite antioxidant additives
Phosphite antioxidant additives are involved in antioxidant protection mainly due to the decomposition of hydroperoxides.
For example, Antioxidant Additives 168, whose chemical name is tris(2,4-di-tert-butylphenyl)phosphite, has CAS No. 31570-04-4. It is a phosphite antioxidant widely used in polymer processing and stabilization.
It is important to note that Antioxidant Additives 168 are widely used in the production of plastics and polymeric materials. However, it cannot be considered as a universal antioxidant additive for all lubricant formulations. Suitability for a specific oil system must be assessed based on component compatibility and test results.
4. Combined antioxidant systems
For high performance lubricants of oneAntioxidant additivesmay not be sufficient to achieve all required characteristics.
The combination of components with different mechanisms of action makes it possible to influence different stages of the oxidative process, including the binding of free radicals and the decomposition of peroxides. In this case, the ratio of components must be selected during laboratory research and testing of the finished recipe.
5. Main industrial applications Anti-oxidation additives
Antioxidant additives are widely used in various lubricants and industrial oils. Since operating temperatures, loads and operating conditions of equipment vary, the requirements for oxidation stability also vary.
| Scope of application | Major Risk Factors for Oxidation | Value Antioxidant additives |
| Motor oils | High temperature, oxygen and oil contact with metal surfaces | Slowing down base oil oxidation, controlling the increase in acid number and the formation of oxidative deposits |
| Turbine oils | Long continuous operation and thermal oxidation | Increased thermal-oxidative stability and extended oil service life |
| Hydraulic oils | Constant circulation, temperature changes and accumulation of oxidation products | Maintains oil stability and reduces the risk of changes in oil characteristics due to oxidation |
| Industrial gear oils | High loads and local heating | Reduces the risk of oxidative degradation and maintains lubricity |
| Transformer oils | Long-term operation and exposure to oxygen | Slows oxidation and maintains insulating oil performance |
| Greases | Oxidation of base oil and thickener during storage and operation | Slows down oxidative degradation and improves stability during storage and use |
In addition, antioxidant additives are used in compressor, circulation, coolant and other special industrial oils, depending on the requirements of specific equipment.
Manufacturers of lubricants need to select antioxidant additives taking into account the operating conditions of the equipment, the type of base oil and the requirements for the finished product. Using the same additive for all types of oils does not always provide the required characteristics.
6. How to choose suitable antioxidant additives for lubricants?
When choosing an antioxidant additive, it is important to consider not only its own antioxidant effectiveness, but also its compatibility with the base oil and other functional components of the formulation.
1. Consider the type of lubricant
Different types of oils operate under different conditions and have different requirements for antioxidant protection.
- Motor oils:Particular attention is paid to thermal-oxidative stability, acid number change and deposit control.
- Turbine oils:Resistance to oxidation during long-term operation and stability of characteristics are important.
- Hydraulic oils:It is necessary to take into account not only oxidation stability, but also filterability, as well as compatibility with other additives.
- Industrial gear oils:the choice must take into account equipment load, operating temperature and lubricity requirements.
2. Choose an additive based on the chemical type
Phenolic, aromatic amine and peroxide-degrading antioxidant additives have different mechanisms of action.
For formulations with increased requirements for antioxidant stability, the applicability of various types of antioxidant additives and the possibility of their joint use should be assessed, taking into account the operating conditions of the finished product.
3. Check compatibility with base oil and other additives
Anti-oxidation additives must be compatible with the base oil, detergent and dispersant additives, anti-wear components and other functional additives.
When developing a formulation, it is necessary to take into account solubility, storage stability, low-temperature properties and possible interactions between individual components.
4. Prove effectiveness with practical tests
The final selection of antioxidant additives should be based on laboratory testing and testing under conditions appropriate to the intended application.
The main assessment indicators include:
- Oxidation induction period time and overall oxidative stability.
- Change in acid number.
- Viscosity change.
- Formation of sludge, varnish films and other oxidation products.
- Compatibility of base oil with additive system.
- Test results provided for by the requirements for a specific type of oil.
One common method for assessing the oxidative stability of lubricants is the rotary bomb test (ASTM D2272). Since different methods involve different test conditions and evaluation criteria, the choice of method must match the requirements of the target product.
There is no universal dosage of antioxidant additives for all formulations. Recommended injection quantities should be determined based on the supplier's technical documentation (TDS) and test results of the finished formulation.
7. Factors affecting the quality of antioxidant additives
For lubricant additive manufacturers, the quality of antioxidant additives depends not only on the chemical structure of the product, but also on the quality of raw materials, synthesis conditions and production control system.
Particular attention should be paid to the following aspects:
Raw material quality control
The purity of starting materials and the content of impurities can affect the course of chemical reactions, the structure of the product and its final characteristics. A stable supply of raw materials is an important basis for ensuring consistency of quality.
Process control
The reaction temperature and duration, the ratio of starting components and other technological parameters must be maintained within specified limits. This reduces the likelihood of adverse reactions and increases the stability of product quality.
Monitoring key indicators
Depending on the type of product and quality requirements, tests are carried out on appearance, purity, content of active ingredients, moisture and other relevant indicators.
Quality consistency between batches
Incoming inspection of raw materials, monitoring of the production process and inspection of finished products help reduce performance variations between individual production batches.
For lubricant manufacturers, consistent product quality, reliable supply and timely technical support are important criteria when choosing a long-term partner.
8. Main trends in the development of antioxidant additives
As engine technology, industrial equipment and lubricant performance requirements evolve, the market places increasingly high demands on the effectiveness and compatibility of antioxidant additives with various formulations.
Main areas of development include:
- Increased antioxidant efficiency.Optimization of molecular structure and mechanisms of action to improve oil protection against oxidation under various temperatures and operating conditions.
- Improving combination technologies.Study of the synergistic interaction of different types of antioxidant additives to improve the overall effectiveness of the antioxidant system.
- Improved component compatibility.Increasing compatibility of antioxidant additives with base oils, detergents and dispersants and other functional components.
- Adaptable to various applications.Development of specialized antioxidant systems for motor, industrial and special lubricants.
- Improving production control.Strengthening control of raw materials, technological processes and quality of finished products to improve the stability of characteristics.
For lubricant additive manufacturers, continuous product development and research into various formulations is an important basis for meeting customer needs and increasing competitiveness.
9. Development and production of additives for lubricants
Lansheng (Jinzhou) Chemistry LLC was founded in April 2018. The company specializes in the development, production and sale of lubricant additives, providing domestic and foreign oil manufacturers with products and formulation development support.
The company's production base occupies approximately 46,667 m² and is equipped with five production lines. The annual production capacity is approximately 60,000 tons. The team includes 9 research and development specialists and 12 engineering and technical specialists. The production uses a closed organization of technological processes and intelligent control systems aimed at increasing the efficiency and stability of product quality.
The company's portfolio includes detergent additives, ashless dispersants, additive packages and other functional components for various lubricant formulations.
In the lubricant additives industry, the company focuses on product development, process improvement and quality management. We take into account the needs of manufacturers for various functional components and offer solutions taking into account the characteristics of their recipes.
We strive to ensure consistent product quality, reliability of supply and compliance with real customer requirements by developing long-term cooperation with lubricant manufacturers and additive package development companies.
Looking for a suitable solution for anti-oxidation protection of lubricants?
Contact Lansheng (Jinzhou) Chemicals LLC to discuss the type of target oil, base oil system used and performance requirements. We will provide product information and provide the necessary technical support.
Frequently asked questions (FAQ)
Question 1. What are Antioxidant Lubricant Additives?
Antioxidant additives are functional components designed to slow down the oxidation of the base oil and other components of the formulation. They scavenge free radicals or promote the decomposition of peroxides, slowing down oxidative chain reactions and helping to control acid number increases, viscosity changes and the formation of oxidative deposits.
Question 2. What are the main types of antioxidant additives?
The main types include phenolic antioxidants, aromatic amine antioxidants, phosphite components and auxiliary thioester antioxidants. They differ in chemical structure, mechanism of action and application features.
Question 3. Why are antioxidant additives added to lubricants?
When exposed to high temperatures and oxygen, lubricants gradually oxidize. This can cause a change in viscosity, an increase in acid number and the formation of deposits. Adding antioxidant additives helps slow down these processes, increase thermal-oxidative stability and extend oil service life.
Question 4. How do phenolic antioxidant additives differ from amine ones?
Both types are capable of binding free radicals and suppressing oxidation chain reactions, but differ in chemical structure, reactivity and application conditions. Phenolic antioxidants generally have good color stability, while aromatic amine antioxidants are often used in systems with increased requirements for high temperature antioxidant protection. The final choice depends on the type of base oil and formulation requirements.
Question 5: Can Anti-Oxidation Additives be used in conjunction with other lubricant additives?
Yes. In ready-made formulations, antioxidant additives are usually combined with detergents, dispersants, anti-wear and other functional components. However, both synergistic and antagonistic effects can occur between individual components. Therefore, the optimal combination must be determined through compatibility testing and performance evaluation.
Question 6. How to determine the dosage of antioxidant additives in the formulation?
Dosage depends on typeAntioxidant additives, properties of the base oil, requirements for the finished product and the composition of other components. It is recommended that the range specified in the supplier's technical documentation (TDS) be used as a starting point, and the final concentration determined by testing for oxidative stability, acid number and viscosity changes, and deposit formation.
