Research Sharing | Functional Applications and Addition Amounts of Diethylenetriamine, Triethylenetetraamine, and Polyethylenepolyamines in Lubricating Oils

Application and dosage analysis of diethylenetriamine, triethylenetetraamine, and polyethylenepolyamine in lubricating oils and lubricants

summary

1.2 Core Mechanism of Action in Lubricants
Ethylene polyamines are rarely added directly to finished lubricating oils; their main value lies in their role as precursors or intermediates for synthesizing high-performance additives . Their core mechanisms of action are manifested in the following three key reactions:
① Reaction with organic acids to form imidazolines, amides, and salts : This is their most important application. Through reaction with long-chain fatty acids (such as oleic acid and stearic acid), imidazoline derivatives or amides are generated, which are excellent rust inhibitors, corrosion inhibitors, and oiliness agents . Reaction with diacids can generate polyamides, used as thickeners or dispersants .
② Condensation with acidic compounds to form ashless dispersants : This is the cornerstone of modern engine oil technology. Ethylene polyamines undergo a condensation reaction with polyisobutylene succinimide (PIBSI) to generate polyisobutylene succinimide (PIBSI-PAM) . This product effectively neutralizes acidic substances produced during combustion and disperses sludge and carbon deposits in the oil, preventing their aggregation and sedimentation, thereby keeping the engine interior clean.
③ As an epoxy curing agent : In certain specialty greases and solid lubricant coatings, ethylene polyamines can act as curing agents for epoxy resins, forming a robust lubricating protective film.
Chapter 2: Specific Application Areas and Dosage Analysis
The applications of ethylene polyamine derivatives cover almost all types of lubricants. The dosage refers not to the direct addition of the polyamine itself, but to the final amount of additives synthesized using it as a key raw material added to the finished lubricating oil.
2.1 Engine Oil
Engine oil is the largest application area for ethylene polyamine derivatives, primarily using ashless dispersants synthesized from them.

Additive types	Core Functions	Main chemical composition	Typical addition amount (wt%) in finished engine oil	Corresponding polyamine raw materials and approximate proportions
Ashless dispersant	Disperses soot and sludge, neutralizes acidic substances.	Polyisobutylene succinimide (PIBSI)	2.0% – 7.0% (Diesel engine oil is typically higher than gasoline engine oil)	In dispersant molecules, the polyamine moiety accounts for approximately 10% to 20% of the total mass of TETA and PEPAs (TEPA being the main component) .
Rust inhibitor	Prevent engine metal parts from rusting	Alkenyl succinic acid imidazoline, polyamine fatty acid salt	0.03% – 0.15%	In rust inhibitor molecules, the polyamine moiety of DETA and TETA accounts for approximately 15% to 30% of their mass .

Application Analysis :
In engine oil additive packages, ashless dispersants are among the single agents with the largest dosage. Their usage depends on the oil grade (e.g., API SN, CK-4) and engine type. High-performance diesel engine oils require dispersants with stronger soot carrying capacity, typically using higher molecular weight dispersants synthesized from TETA or TEPA , and in larger quantities. Calculations show that each ton of finished engine oil actually contains approximately 0.2% – 1.4% ethylene polyamines (i.e., 2-14 kg/ton of oil), reflecting their crucial role as a key intermediate.
2.2 Industrial Lubricants:
Industrial lubricants are diverse, with polyamine derivatives mainly used as rust inhibitors and extreme pressure anti-wear agents.

Oil type	Core requirements	Polyamine derivatives used	Typical addition amount (wt%) in refined oil	Corresponding polyamine raw materials
Gear oil	Extreme pressure anti-wear and rust prevention	Phosphate ammonium salts, imidazoline derivatives	0.5% – 3.0% (as part of the functional agent)	DETA, TETA
hydraulic oil	Rust prevention and deemulsification	Fatty acid imidazoline salts	0.05% – 0.2%	DETA
Metalworking fluids	Lubrication, rust prevention, cleaning	Imidazoline-based rust inhibitors and emulsifiers	0.5% – 5.0% (amount added to the concentrate)	DETA, TETA

Application Analysis :
In industrial lubricants, the addition amount of polyamine derivatives is relatively flexible, depending on the severity of the operating conditions. For example, in heavy-duty gear oils, a higher dose of ammonium phosphate may be required to provide extreme pressure protection. In metalworking fluid concentrates, the addition amount of imidazoline rust inhibitors can be high to ensure good inter-process rust prevention even after dilution with water.
2.3 Grease
Grease is a semi-fluid product made by thickening lubricating oil with a thickener. Polyamine derivatives have unique applications in this field.

Function	Specific applications	WT% ) to grease	Corresponding polyamine raw materials
Rust inhibitor	Fatty acid imidazolines and amides	0.5% – 3.0%	DETA, TETA
Composite thickener	Salts of dodecyl stearic acid and DETA/TETA	5.0% – 15.0% (as a component of the thickener)	DETA, TETA
Epoxy curing agent	Used for preparing solid lubricating coatings	Variable, calculated in chemical equivalents	DETA, TETA, PEPAs

Application Analysis :

In lubricating greases, polyamines not only serve as functional additives but also directly participate in the construction of product structure. For example, the thickener of complex lithium-based lubricating greases is formed by lithium soap and organic acid salts of DETA or TETA . In this application, the amount of polyamine used is considerable, making it one of the key materials constituting the main body of the product.
2.4 Total Estimation and Data Summary By synthesizing
data from various fields, a rough estimate can be made of the annual consumption of ethylene polyamines in the global lubricating oil industry.

Application areas	Global annual consumption (million tons)	Average addition amount of polyamine derivatives	Polyamine content in derivatives	Annual consumption of polyamines (thousand tons)	Main types of polyamines used
Engine oil	~40	4.0%	15%	~ 240	TETA, PEPAs
Industrial lubricants	~15	0.5%	20%	~ 15	DETA, TETA
grease	~1.2	2.0%	25%	~ 6	DETA, TETA
total				~261

Note: The above data is an estimate based on industry reports, intended to reflect orders of magnitude and proportional relationships. Actual figures may fluctuate with market and technological changes. This estimate indicates that the global lubricant industry may consume more than
260,000 tons of ethylene polyamines (pure) annually , with engine oil being the undisputed largest consumer , and demanding TETA and higher molecular weight PEPAs the most.
Chapter 3: Trends, Challenges, and Outlook
3.1 Future Trends
① High Performance Demand : As engines move towards smaller size and higher power density, the requirements for lubricant cleanliness, dispersibility, and oxidation resistance are increasing. This will drive demand for PEPAs (such as TEPA, PEHA) , whose high molecular weight, high base number dispersants can more effectively handle more soot and acidic substances.
② Low Sulfurization and Compatibility : To protect aftertreatment devices (such as DPF, GPF), lubricants are trending towards low sulfur, low phosphorus, and low ash (Low SAPS). This requires additive manufacturers to optimize the molecular structure of polyamine derivatives to maintain or even improve performance while reducing metal content (ash).

    ③ Expansion into the new energy field : In hybrid electric vehicles (HEVs) and range-extended electric vehicles (EREVs), engine operating conditions are more demanding, with frequent start-stop cycles, placing new requirements on the wear resistance and cleanliness of the oil. In electric vehicles, polyamine derivatives can be used as corrosion inhibitors in transmission fluids and thermal management fluids.

3.2 Outlook:
Ethylene polyamines, especially DETA, TETA, and PEPAs, will remain core structural materials in lubricant additive chemistry for a long time to come due to their irreplaceable chemical properties and flexible modifiability. Future development will focus on:
Refined molecular design : Customizing the synthesis of more specific and efficient derivatives by precisely controlling the degree of polymerization, distribution, and reaction sites of polyamines. Diversified application areas : Penetrating emerging environmentally friendly fields such as bio-based lubricants and biodegradable lubricants.
Green processes : Developing lower energy consumption and higher atom economy synthesis processes to reduce emissions of waste.
Conclusion :
Although diethylenetriamine (DETA), triethylenetetramine (TETA), and polyethylene polyamines (PEPAs) do not directly appear in the final lubricant product, as key “behind-the-scenes contributors,” they deeply participate in the construction of modern lubricants through the synthesis of various high-performance additives, playing a decisive role in their quality, grade, and lifespan. Data shows that their indirect usage in engine oils is the largest, and with the continuous improvement of lubricant standards, the demand for higher molecular weight PEPAs will continue to grow. Facing future challenges and opportunities, ethylene polyamine compounds will continue to rely on their solid chemical foundation and consolidate their core position in the lubricant industry through continuous technological innovation, providing fundamental chemical support for the efficient, clean, and long-life operation of global machinery and equipment.