The innovative use of polyurethane TPE anti-yellowing agent in agricultural equipment

Date：2025-03-16 Categories：News

Polyurethane TPE anti-yellowing agent: innovative application in agricultural equipment

1. Introduction: From “the hero behind the scenes” to “agricultural pioneer”

In the wave of agricultural modernization, various mechanical equipment is like the “steel warriors” in the fields, protecting the sowing, growth and harvest of crops. However, behind the efficient operation of these devices, there is a material that is often overlooked – it is polyurethane thermoplastic elastomer (TPE). As an important part of modern industry, polyurethane TPE has become one of the indispensable materials in the field of agricultural equipment manufacturing with its excellent performance. However, as the equipment is exposed to natural environments such as sunlight and rainwater for a long time, TPE materials are prone to oxidation and degradation, causing the surface color to gradually turn yellow or even age and crack, seriously affecting its appearance and service life. Therefore, how to effectively prevent this “yellow change” phenomenon has become a technical problem that the industry needs to solve urgently.

It is in this context that polyurethane TPE anti-yellowing agents emerged. This new additive can not only significantly delay the aging rate of TPE materials, but also maintain its original flexibility and mechanical strength, thereby extending the service life of agricultural equipment. More importantly, its emergence offers more possibilities for the design and manufacturing of agricultural equipment. For example, through synergistic effects with anti-ultraviolet stabilizers, anti-yellowing agents can help the equipment maintain good performance in high temperature and high humidity environments; through the combination with flame retardants, the safety of the equipment can be further improved. It can be said that polyurethane TPE anti-yellowing agent is not only a technological breakthrough in the field of materials science, but also a key force in promoting the development of agricultural equipment towards high performance and long life.

This article will conduct in-depth discussions on polyurethane TPE anti-yellowing agent, covering its basic principles, product parameters, application scenarios, and domestic and foreign research progress. At the same time, we will also demonstrate the practical application effect of this innovative material in agricultural equipment through specific case analysis. This is a rare feast of knowledge for materials scientists and agricultural engineers.

2. Basic principles of polyurethane TPE anti-yellowing agent

To understand the mechanism of action of polyurethane TPE anti-yellowing agent, you first need to understand why TPE materials turn yellow. Simply put, TPE is a block copolymer composed of hard segments and soft segments, where the hard segment is mainly responsible for providing the strength and rigidity of the material, while the soft segment imparts flexibility and elasticity. However, when TPE is exposed to external environmental factors such as ultraviolet light, oxygen or high temperature, a series of complex chemical reactions will occur in its molecular structure, which will eventually lead to deterioration in material performance and changes in appearance.

(I) Causes and processes of yellowing

Photooxidation reaction
Ultraviolet light is one of the main reasons for yellowing of TPE. When ultraviolet rays hit the surface of TPE, it will stimulateUnsaturated bonds in the material form free radicals. These free radicals then react with oxygen in the air to produce peroxides and other oxidation products, which gradually turn the material yellow.
Thermal oxygen aging
Under high temperature conditions, the polymer chains in TPE may be broken or cross-linked, further exacerbating the aging process of the material. Especially in agricultural equipment, TPE is more susceptible to the threat of thermal oxygen aging due to long-term operation and frequent contact with soil, moisture and other factors.
Impurity Effect
If the TPE raw material contains trace amounts of metal ions or other catalyst residues, it may also accelerate its yellowing process. This is because these impurities promote the formation of free radicals, thereby speeding up the oxidation reaction.

(II) Mechanism of action of anti-yellowing agent

To combat the above problems, polyurethane TPE anti-yellowing agents adopt various strategies to inhibit the occurrence of yellowing:

Free Radical Capture
One of the core functions of anti-yellowing agents is to capture and neutralize free radicals, preventing them from continuing to participate in the oxidation reaction. For example, phenolic antioxidants can convert free radicals into stable compounds by providing hydrogen atoms, thereby terminating the chain reaction.
Ultraviolet absorption
Some anti-yellowing agents also have ultraviolet absorption capacity, which can convert the energy of ultraviolet light into harmless heat and release it, avoiding its direct effect on TPE materials. This function is similar to putting a layer of “sun protection clothes” on TPE.
Metal ion passivation
In response to the yellowing problem caused by impurities, anti-yellowing agents can bind to metal ions through chelation to reduce their catalytic activity, thereby slowing down the speed of the oxidation reaction.
Synergy Effect
It is worth mentioning that many anti-yellowing agents do not function alone, but form synergistic effects with other additives (such as light stabilizers, thermal stabilizers, etc.) to jointly improve the overall weather resistance of TPE.

(III) Types and characteristics of typical anti-yellowing agents

Depending on the chemical structure and function, polyurethane TPE anti-yellowing agents can be divided into the following categories:

Category	Main Ingredients	Functional Features	Scope of application
Phenol antioxidants	Tert-butylphenol, bisphenol A	Catch free radicals and delay oxidation reaction; good thermal stability	Agricultural equipment shells in high temperature environments
Amine antioxidants	P-phenylenediamine, aromatic amine	Provides stronger free radical scavenging ability; may have certain toxicity	Special purpose seals and wear-resistant components
Phosphate anti-yellowing agent	Triphenylphosphite, trimethylphosphate	It has both oxidation resistance and flame retardant properties; improves material processing fluidity	Agricultural Vehicle Interior Parts and Safety Protection Devices
Organic nickel compound	Nickel salts, nickel chelates	Inhibit the formation of carbonyl compounds and reduce yellowing; suitable for light or transparent products	Agricultural Machinery Dashboard and Decorative Panel
Ultraviolet absorber	Benzotriazole, salicylate	Absorbs ultraviolet energy to protect the material from photoaging	Farm tools and covering films for long-term outdoor use

By reasonably selecting and matching these anti-yellowing agents, TPE formulas suitable for different agricultural equipment can be customized according to specific needs, thereby achieving good anti-yellowing effect.

3. Detailed explanation of product parameters of polyurethane TPE anti-yellowing agent

As a functional additive, the performance parameters of polyurethane TPE anti-yellowing agent directly determine their performance in practical applications. The following are several key indicators and their significance:

(I) Addition amount

The amount of the anti-yellowing agent added is usually expressed as mass percentage, generally between 0.1% and 2%. Too low addition may lead to insufficient anti-yellowing effect, while too high may affect other performance of TPE. For example, for some agricultural equipment parts that require high transparency, the amount of anti-yellowing agent added needs to be strictly controlled to avoid increasing haze or decreasing light transmittance.

Additional range (wt%)	Applicable scenarios	Precautions
0.1%-0.5%	Light color or transparent products	Ensure uniform dispersion and avoid excessive local concentration
0.5%-1.0%	General-purpose agricultural equipment shell	Adjust the ratio according to the specific formula
1.0%-2.0%	High-strength components under extreme conditions	Extra test for compatibility may be required

(II) Temperature resistance

The temperature resistance of the anti-yellowing agent refers to its ability to maintain effectiveness under high temperature environments. Generally speaking, high-quality anti-yellowing agents can operate stably in the range of 100°C to 200°C. However, if agricultural equipment is often in higher temperature working environments, a specially designed anti-yellowing agent needs to be selected.

Temperature range (℃)	Recommended anti-yellowing agent types	Application Examples
≤100	Phenol antioxidants	Light tools in agricultural greenhouses
100-150	Phosphate anti-yellowing agent	Rubber seal strips for agricultural tractors
≥150	Organic nickel compound	High-speed rotating agricultural machinery transmission components

(III) Mobility

Mobility refers to the tendency of anti-yellowing agents to diffuse outward from the TPE matrix. If the mobility is too high, the anti-yellowing agent may gradually lose during use, resulting in a weakening of the anti-yellowing effect. Therefore, when designing agricultural equipment, low mobility anti-yellowing agents should be preferred.

Migration Level	Test Method	Result Evaluation
Low	ASTM D6978 Dissolution Test	≤0.1mg/cm², suitable for long-term use
in	ISO 105-B02 sweat stain test	0.1-0.5mg/cm², required regular maintenance
High	Custom simulation experiment	>0.5mg/cm², only forShort-term application

(IV) Environmental protection

As the global focus on environmental protection is increasing, the environmental protection of anti-yellowing agents has also become one of the important criteria for measuring their advantages and disadvantages. Ideal anti-yellowing agents should have good biodegradability and low toxicity to reduce the impact on the ecological environment.

Environmental Certification	Complied with standards	Example Product
REACH	EU Chemical Registration, Evaluation and Authorization Regulations	BASF Irganox Series Anti-Yeling Agent
RoHS	Suppression of hazardous substances directive	Clariant Hostanox Series Anti-Yeling Agent
FDA	US Food and Drug Administration Standards	DuPont Zerust series anti-yellowing agent

IV. Application scenarios of polyurethane TPE anti-yellowing agent in agricultural equipment

The application range of polyurethane TPE anti-yellowing agent is very wide, covering almost all types of agricultural equipment. Here are some typical examples:

(I) Agricultural Machinery Case

The shell of agricultural machinery not only needs to withstand the erosion of the external environment, but also maintain a good appearance. By adding an appropriate amount of anti-yellowing agent, the shell can still maintain a bright color and smooth surface after long-term use. For example, a tractor cab ceiling made of TPE material, after adding 0.5% phenolic antioxidants, the yellow index change value is only 2.3, far lower than the 15.6 of the untreated sample after being exposed to the sun for a year.

(II) Irrigation system accessories

In modern irrigation systems such as drip irrigation and sprinkler irrigation, TPE materials are often used to make key components such as hose joints and valve seals. These components are immersed in water for a long time and are susceptible to microbial contamination and chemical corrosion. By introducing anti-yellowing agents, it not only extends its service life, but also ensures smooth water flow. Studies have shown that TPE hoses containing phosphate anti-yellowing agents have improved hydrolysis resistance by about 40%, and there are no obvious signs of aging after two consecutive years of operation.

(III) Agricultural film

Agricultural films are an important tool to protect crops from bad weather. However, traditional polyethylene films tend to become brittle under ultraviolet raysYellow seriously affects its light transmittance and thermal insulation effect. By combining TPE with UV absorbers and anti-yellowing agents, a new composite film can be developed, with a service life of nearly three times longer than that of ordinary films, while also better meeting the needs of modern agricultural production.

5. Domestic and foreign research progress and future prospects

In recent years, research on polyurethane TPE anti-yellowing agents has achieved many breakthrough results. For example, Bayer, Germany, has developed an anti-yellowing agent based on nanotechnology, which has better dispersion and stability than traditional products; Dow Chemical in the United States has launched a multifunctional composite anti-yellowing agent, which can achieve various functions such as antioxidant, anti-ultraviolet and flame retardant in the same formula.

However, despite the continuous advancement of technology, the research and development of polyurethane TPE anti-yellowing agents still faces many challenges. First of all, there is a cost issue. The price of high-performance anti-yellowing agents is often higher, which limits its promotion in the low-end market; secondly, there is a problem of standardization. There is currently a lack of a unified testing method and evaluation system, which makes it difficult for products from different manufacturers to be compared horizontally.

Looking forward, with the introduction of emerging technologies such as artificial intelligence and big data, the research and development of anti-yellowing agents will be more accurate and efficient. In addition, the popularization of green chemistry concepts will also prompt the industry to develop in a more environmentally friendly direction. We have reason to believe that in the near future, polyurethane TPE anti-yellowing agents will play a greater role in the field of agricultural equipment and create more value for mankind.

6. Conclusion: Small additives, big ones

Although polyurethane TPE anti-yellowing agent is just a small additive, the meaning it carries is extraordinary. It not only solves the long-lasting problem of TPE materials turning yellow, but also injects new vitality into the upgrading and replacement of agricultural equipment. As a poem says: “The true chapters are seen in the subtleties, and miracles are hidden in the ordinary.” Let us look forward to the fact that in this era full of opportunities, polyurethane TPE anti-yellowing agent can continue its wonderful chapters!

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