TPU yellowing agent: Provides consumers with a healthier user experience
1. Preface: Start with “yellow change”
In daily life, have you ever encountered such a situation: after wearing a brand new white sneaker for a while, the soles gradually turn yellow; or your carefully selected transparent plastic products will become dull after being exposed to the sun for a while? These phenomena are actually caused by “yellow change”. Yellowing refers to the fact that the material gradually loses its original transparency or whiteness under the influence of light, oxygen, heat or other environmental factors, and appears yellow or even brown. For consumers, this change not only affects the appearance, but may also imply a decline in product performance and even brings health risks.
To deal with this problem, scientists have developed a magical substance – TPU yellowing agent. It is like an invisible guardian, silently protecting various thermoplastic polyurethane (TPU) materials from yellowing. TPU is a widely used elastomeric material, widely used in shoe materials, electronic products, medical equipment and automotive parts and other fields. However, the TPU itself is more sensitive to ultraviolet rays and high temperatures and is prone to yellowing. The emergence of TPU yellowing agents has solved these problems.
This article will explore in-depth the principles, types, applications of TPU yellowing agents and how to provide consumers with a healthier user experience. We will also combine domestic and foreign literature and use easy-to-understand language and vivid metaphors to help readers better understand the importance of this technology and the scientific mysteries behind it.
2. Basic knowledge of TPU yellowing agent
(I) What is TPU?
TPU, thermoplastic polyurethane elastomer (Thermoplastic polyurethane), is a high-performance material with high elasticity, wear resistance and tear resistance. It can be processed repeatedly by heating, so it is called “thermoplastic”. The molecular structure of TPU contains hard and soft segments, which give it high strength and rigidity, while the soft segment provides flexibility and elasticity. Because of this, TPU is widely used to manufacture shoe soles, mobile phone cases, cable sheaths, medical devices and other products.
However, TPU also has a fatal weakness: it is very sensitive to UV and high temperatures. When exposed to sunlight or high temperature environments, chemical bonds in the TPU can break or recombinate, causing the material surface to gradually turn yellow. This yellowing not only affects the appearance of the product, but may also lead to a decrease in mechanical properties and even shorten the service life.
(II) Analysis of the causes of yellowing
-
Ultraviolet rays
Ultraviolet rays are one of the main reasons for TPU yellowing. When the TPU is exposed to ultraviolet light, some groups in its molecular chain absorb ultraviolet energy, which in turn causes theThe radical reaction eventually leads to changes in the molecular structure and forms colored compounds. -
Oxidation
In the air, oxygen reacts with active groups in the TPU to produce peroxides and other by-products, which also cause discoloration of the material. -
Thermal Aging
Under high temperature conditions, the molecular chain of TPU may undergo degradation or cross-linking reactions, thereby changing its optical properties and making it look yellow or brown. -
The Effect of Additives
If certain additives (such as plasticizers, antioxidants) are not selected properly, they may also accelerate the yellowing process of the TPU.
(III) Definition and function of TPU yellowing agent
TPU yellowing agent is a chemical additive specially used to inhibit TPU yellowing. Its main functions include:
- Absorb UV rays and convert them into harmless heat;
- Interrupt the free radical chain reaction to prevent oxidative degradation;
- Improve the thermal stability of the TPU and reduce molecular structure changes caused by high temperature.
Addition of TPU material can be significantly delayed by adding an appropriate amount of yellowing agent, and maintain its long-term beauty and performance.
3. Classification and characteristics of TPU yellowing agent
Depending on the chemical composition and mechanism of action, TPU yellowing agents can be divided into the following categories:
| Category | Main Ingredients | Features | Application Fields |
|---|---|---|---|
| Ultraviolet absorber | Benzotriazoles, salicylates | Can effectively absorb ultraviolet rays at wavelengths of 290-400nm to prevent photochemical reactions | Outdoor supplies, auto parts |
| Free Radical Capture | Hardened amines (HALS), phenols | Interrupt the free radical chain reaction and slow down the oxidation process | Medical devices, electronic devices |
| Antioxidants | Phosophate, thiodipropionate | Provide long-term antioxidant protection to delay thermal aging | Shoe materials, industrial films |
| ComprehensiveCombined yellowing resistance agent | Combined with multiple ingredients | It has multiple protection functions, suitable for applications in complex environments | High-end consumer goods |
(I) UV absorber
UV absorbers are a type of yellowing-resistant agent that has been developed long ago. Their working principle is similar to the UV-proof coating on sunglasses. They can selectively absorb UV rays of specific wavelengths and release their energy in the form of thermal energy, thereby avoiding the damage of UV rays to TPU molecules.
Common types:
-
Benzotriazoles
This is one of the commonly used UV absorbers, which has high efficiency, low volatility and good weather resistance. For example, BHT (2,6-di-tert-butyl p-cresol) is a typical benzotriazole compound. -
Salicylate
Because of their excellent solubility and stability, salicylate compounds are often used in applications where high transparency is required, such as optical lenses and display housings.
(Bi) Free radical capture agent
The role of the radical capture agent is to capture the free radicals generated by TPU molecules during the oxidation process, thereby interrupting the chain reaction. This type of yellowing agent usually has a large molecular weight and complex chemical structure, which can continue to function for a long time.
Common types:
-
Hardened amines (HALS)
HALS is a highly efficient free radical capture agent. Its molecules contain nitrogen atoms and can continuously consume free radicals through regeneration cycles. In addition, HALS also has certain light stability properties and can be used in conjunction with other yellowing agents. -
Phenol antioxidants
Phenol compounds neutralize free radicals by sacrificing their own molecular structure, thus protecting the TPU from damage. They are usually used as auxiliary antioxidants.
(III) Antioxidants
Antioxidants are mainly used to delay the aging process of TPU under high temperature conditions. They reduce the risk of oxidation by reacting with oxygen molecules, preventing them from contacting TPU molecules.
Common types:
-
Phosate
Phosphate antioxidants have good thermal stability and compatibility and are suitable for high-temperature processing environments. -
Thiodipropionate
Such compounds are known for their efficient antioxidant properties, but may affect the transparency of the TPU, so they are mostly used in opaque products.
(IV) Comprehensive yellowing resistance agent
As the continuous increase in market demand, researchers have begun to develop comprehensive yellowing agents, that is, to combine multiple single-function yellowing agents to achieve a more comprehensive protection effect. For example, some high-end products include both UV absorbers, free radical trapping agents and antioxidants, which can adapt to the needs of use in extreme environments.
IV. Application examples of TPU yellowing agent
TPU yellowing agents have an extremely wide range of applications, covering almost all industries involving TPU materials. The following are some typical application cases:
(I) Sports soles
Modern sports soles are mostly made of TPU material because they are light, soft and wear-resistant. However, after wearing it for a long time, the soles may turn yellow due to ultraviolet rays, affecting the overall appearance. By adding an appropriate amount of ultraviolet absorber and free radical capture agent, this problem can be effectively prevented and the sole remains as white as new.
(II) Mobile phone case
As a high-frequency consumer product, the appearance design of the mobile phone case is crucial. However, many transparent mobile phone cases will experience obvious yellowing after exposure to the sun, which not only affects the visual effect, but may also reduce consumers’ willingness to buy. To do this, manufacturers usually add antioxidants and UV absorbers to the TPU feedstock to ensure long-lasting transparency and luster.
(III) Medical Devices
In the medical field, TPU materials are widely used in the production of disposable medical devices such as catheters and infusion bags due to their biocompatibility and flexibility. However, these products may be affected by UV or oxygen during storage or use, resulting in a degradation in performance. By introducing appropriate yellowing agents, the reliability and safety of the product can be significantly improved.
V. Research progress of TPU yellowing agent
In recent years, with the advancement of technology and the enhancement of environmental awareness, the research and development direction of TPU yellowing agents has also been constantly adjusting. Here are some research trends worth paying attention to:
(I) Green development
Some ingredients in traditional yellowing agents (such as heavy metal salts) may cause harm to human health and the environment. Therefore, scientists are working to develop more environmentally friendly alternatives. For example, natural antioxidants based on plant extracts are gradually becoming a research hotspot.
(II) Multifunctional design
To meet the needs of different application scenarios, researchers are trying to integrate multiple functions into a single yellowing agent. For example,These new composite materials not only have yellowing resistance, but also provide antibacterial and antistatic functions.
(III) Intelligent regulation
With the development of smart material technology, yellowing agents that can automatically adjust the protection strength according to changes in the external environment may appear in the future. This material will greatly enhance the durability and adaptability of TPU products.
VI. Market prospects of TPU yellowing agent
As the global consumer market continues to expand, the demand for TPU yellowing agents is also increasing year by year. According to relevant statistics, it is estimated that by 2030, the global TPU yellowing agent market size will reach billions of dollars. Among them, the Asia-Pacific region will become the main consumer market due to its huge population base and rapidly developing economic level.
At the same time, governments have increasingly strict requirements on environmental protection, which will also promote the green transformation of the yellowing agent-resistant industry. Those companies that can take the lead in mastering core technologies and launch products that meet environmental standards will occupy an advantageous position in future market competition.
7. Conclusion: Make life better
Although TPU yellowing agent seems inconspicuous, it is an important contributor to ensure the quality and life of TPU materials. By using yellowing agent scientifically and reasonably, we can enable various TPU products to maintain good appearance and performance for a longer period of time, thereby providing consumers with a healthier and more comfortable user experience.
As a poem says, “Time is like a knife, but it is hard to hurt me.” With the protection of TPU yellowing agent, our lives will become more colorful!
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