The application of anti-yellowing agent on winter snow boots to prevent color changes caused by low temperatures

March 16, 2025by admin0

Anti-yellowing agent for soles: Keep snow boots “youthful” in the cold winter

1. Introduction: The Winter Challenge of Snow Boots

Winter is a grand art exhibition of nature. The white snowflakes fell from the sky like an elf, covering the earth with a layer of silver. However, for those who love beauty, winter is also an adventure to fight against the cold and slippery weather. Especially when we wear our beloved snow boots and embark on snow-covered roads, we always worry about one question: Why does the soles turn yellow over time? This not only affects the overall beauty of the shoes, but also makes people feel extremely frustrated.

Structure and material of snow boots

Snow boots are usually composed of soft wool lining, waterproof outer layer, and thick rubber or TPU (thermoplastic polyurethane) soles. This design is warm and non-slip, making it ideal for walking on snow-covered grounds. However, it is certain components in these materials that tend to react chemically in low temperature environments, causing changes in the color of the sole. Especially rubber materials, because their internal structure contains unsaturated bonds, they are easily affected by oxygen and ultraviolet rays, resulting in oxidation and yellowing.

The importance of anti-yellowing agents

In order to protect the beauty of snow boots and extend their service life, scientists have developed a magical substance – an anti-yellowing agent. It is like a loyal guard, always guarding the color of the soles from outside. By adding an appropriate amount of anti-yellowing agent to the production process, the aging process of sole materials can be effectively inhibited, so that the snow boots can still maintain their fresh appearance even after several cold winters.

Next, we will conduct in-depth discussion on the specific mechanism of action, type selection and practical application cases of anti-yellowing agents, and conduct detailed analysis based on relevant domestic and foreign literature. I hope this article will unveil the mystery of this field for you and give you a deeper understanding of the maintenance of snow boots.

2. The principle of action of anti-yellowing agent: the power of science

To understand how anti-yellowing agents work, we first need to understand why the soles turn yellow in low temperature environments. Simply put, this phenomenon mainly stems from the oxidation reaction that occurs inside the material. When rubber or TPU is exposed to air, double bonds or other active groups in it react with oxygen to form a complex series of peroxides. These peroxides further decompose to produce carbonyl compounds such as aldehydes and ketones, which absorb visible light and make the material look yellow or brown.

Basic process of oxidation reaction

Initiation stage: Formation of free radicals
Under ultraviolet irradiation or high temperature conditions, the C-H bond in the rubber molecule breaks and forms free radicals. These free radicals are very active and react quickly with other molecules.
Propagation phase: Expansion of chain reaction
Free radicals bind to oxygen to form peroxy radicals, which continue to attack other rubber molecules, causing the reaction to continue to spread.
Termination Phase: Annihilation of Free Radicals
When two radicals meet, they bind to each other to form a stable compound, thus ending the reaction.

However, in practical cases, the termination phase often fails to completely prevent the activity of all free radicals, so the oxidation reaction will continue, eventually leading to material aging and discoloration.

Instrument of anti-yellowing agent: interrupting the reaction chain

The core function of anti-yellowing agent is to intervene in the above-mentioned oxidation reaction process, which is specifically reflected in the following aspects:

Catch free radicals
Certain types of anti-yellowing agents (such as hindered amine compounds) are able to directly capture free radicals and convert them into products with higher stability, thus disrupting chain reactions.
Decompose peroxide
Peroxides are key intermediates in the oxidation reaction, and some anti-yellowing agents (such as phosphites) can catalyze the decomposition of peroxides to reduce their damage to the material.
Shield UV rays
Ultraviolet rays are one of the important factors that trigger oxidation reactions. Light stabilizers (such as benzotriazoles) can absorb UV energy, preventing them from penetrating into the inside of the material, thereby delaying the occurrence of yellowing.
Providing an antioxidant barrier
By forming a protective film on the surface of the material, the anti-yellowing agent can also isolate the oxygen in the air, reducing the possibility of an oxidation reaction.

Example description: The actual effect of anti-yellowing agent

Suppose there is a pair of ordinary snow boots without an anti-yellowing agent, and the rubber soles may have obvious yellow spots after a winter. If a suitable anti-yellowing agent is added during the production process, the sole can still maintain its original light gray or transparent appearance even under the same conditions of use.

The following table summarizes the main characteristics and scope of application of several common anti-yellowing agents:

Category	Chemical Name	Main Functions	Pros	Disadvantages
Stealed Phenols	Tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester	Catch free radicals	Excellent effect and strong durability	May affect material hardness
Trumped amines	Bis(2,2,6,6-tetramethyl-4-yl)sebamate	Decomposition of peroxides	Especially effective for photooxidation	High cost
Phosophites	Tris(nonylphenyl)phosphite	Decomposition of peroxides	Good thermal stability	Easy to migrate
Benzotriazoles	2-(2′-hydroxy-5′-methylphenyl)benzotriazole	Absorb UV rays	Excellent photostability	Not suitable for dark materials

By rationally selecting and matching these anti-yellowing agents, manufacturers can customize the best solutions according to different product needs.

3. Classification and selection of anti-yellowing agents: Find a suitable partner

Just like there are no two identical snowflakes in the world, each anti-yellowing agent has its own unique characteristics and applicable scenarios. In order to help everyone better understand these “behind the scenes”, we will introduce them in detail according to different classification standards below.

1. Classification by chemical structure

(1) Barriered phenolic anti-yellowing agent

The hindered phenolic anti-yellowing agent is one of the common antioxidants and has strong free radical capture ability. They usually have phenolic hydroxyl groups as the core structure, surrounded by multiple alkyl substituents, forming the so-called “stereosteric hindrance effect.” This structure allows hindered phenolic compounds to efficiently remove free radicals and not easily cause adverse reactions with other substances.

Typical representatives include BHT (2,6-di-tert-butyl-4-methylphenol) and Irganox 1010. This type of anti-yellowing agent is widely used in various rubber products, but due to its low molecular weight, it is easy to migrate from the material to the surface, so additional additions may be required during long-term use.

(2) Barriered amine anti-yellowing agent

The hindered amine anti-yellowing agent is known for its excellent light stability. They neutralize free radicals in the material by releasing nitrogen oxygen radicals, while also promoting the decomposition of peroxides. In addition, hindered amine compounds also have certain synergistic effects, which can be combined withOther types of antioxidants work together to enhance the overall effect.

Common hindered amine anti-yellowing agents include Tinuvin 770 and Chimassorb 944. Despite their relatively high prices, they are still very popular in high-end snow boot manufacturing.

(3) Phosphite anti-yellowing agent

Phosophite anti-yellowing agents mainly achieve antioxidant functions by catalyzing the decomposition of peroxides. Their molecular structure contains phosphorus and oxygen bonds, which can maintain good thermal stability under high temperature conditions. Therefore, such anti-yellowing agents are particularly suitable for rubber products with higher processing temperatures.

Representative products include Tris(2,4-di-t-butylphenyl) phosphite and Irgafos 168. However, it should be noted that phosphite compounds are easily migrated from the material, so they should be controlled during use.

(4) Benzotriazole anti-yellowing agent

Benzotriazole anti-yellowing agent is a highly efficient ultraviolet absorber that can convert the energy of ultraviolet rays into harmless heat energy and release it. Their molecular structure contains benzotriazole rings, which give them extremely strong ultraviolet light absorption capacity.

Typical benzotriazole anti-yellowing agents include Tinuvin P and Cyasorb UV-531, etc. Due to its excellent light stability, this type of anti-yellowing agent is often used in rubber products for outdoor use.

2. Classification by function

In addition to classification according to chemical structure, we can also classify anti-yellowing agents according to their functions. Here are the main types:

(1) Main anti-yellowing agent

Main anti-yellowing agents refer to those main components that can directly participate in the oxidation reaction and prevent it from happening. For example, hindered phenols and hindered amines are in this category.

(2) Auxiliary anti-yellowing agent

Although the auxiliary anti-yellowing agent cannot work alone, it can work in conjunction with the main anti-yellowing agent to improve the overall effect. Phosphite anti-yellowing agents are a typical example.

(3) Photo stabilizer

Light stabilizers are specifically designed to resist yellowing problems caused by ultraviolet rays. Benzotriazole anti-yellowing agents are representative of this type of product.

3. How to choose the right anti-yellowing agent?

In practical applications, the following factors need to be considered comprehensively:

Material Type: Different materials have different compatibility with various anti-yellowing agents. For example, natural rubbers are more suitable for the use of hindered phenolic anti-yellowing agents, while synthetic rubbers may require the combination of hindered amines and phosphite anti-yellowing agents.
User Environment: If snow boots are mainly worn indoors, you can choose a lower-cost anti-yellowing agent; but if it is used outdoors with direct sunlight, you need to use a high-performance light stabilizer.
Processing Conditions: Processing process under high temperature and high pressure may cause certain anti-yellowing agents to fail, so it is necessary to ensure that the selected product can withstand the corresponding process requirements.
Cost Budget: Of course, economic factors are also an aspect that cannot be ignored. On the premise of meeting performance requirements, try to select cost-effective anti-yellowing agents.

IV. Examples of application of anti-yellowing agents in snow boots: theory and practice

In order to more intuitively demonstrate the practical application effect of anti-yellowing agents, we selected several typical cases for analysis.

Case 1: A brand of high-end snow boots

The brand’s snow boots use imported TPU material as the sole and have a composite anti-yellowing agent formula. The specific composition is: hindered phenol anti-yellowing agent (3%), hindered amine anti-yellowing agent (2%) and phosphite anti-yellowing agent (1%). After a year of outdoor testing, the results showed that the sole color had almost no changes and the physical performance was maintained.

Test items	Initial Value	Post-test value	Rate of Change
Color Index (L*)	90.5	89.8	-0.77%
Tension Strength (MPa)	25.0	24.5	-2.00%
Elongation of Break (%)	450	430	-4.44%

Case 2: Economy snow boots

For price-sensitive consumers, another brand has launched snow boots with domestic EPDM rubber soles and has added only a single hindered phenol anti-yellowing agent (2%). Although the cost is significantly reduced, after the same cycle of testing, the sole color showed slight yellow marks.

Test items	Initial Value	Post-test value	Rate of Change
Color Index (L*)	88.0	86.2	-2.05%
Tension Strength (MPa)	20.0	19.0	-5.00%
Elongation of Break (%)	400	370	-7.50%

Case 3: Adaptive snow boots in special environments

In view of the needs of Arctic explorers, a professional outdoor brand has developed a snow boot for extreme low temperature environments. Its sole is made of modified silicone rubber and is equipped with a high concentration of benzotriazole light stabilizer (5%) and hindered amine anti-yellowing agent (4%). Even under the harsh conditions of minus 50 degrees Celsius, the sole still shows excellent anti-yellowing properties.

Test items	Initial Value	Post-test value	Rate of Change
Color Index (L*)	92.0	91.5	-0.54%
Tension Strength (MPa)	30.0	29.8	-0.67%
Elongation of Break (%)	500	490	-2.00%

From the above cases, it can be seen that the rational choice and use of anti-yellowing agents are crucial to improving the quality of snow boots. At the same time, this also reminds us to fully consider the influence of various factors in actual operation to achieve optimal application results.

5. Current status and development prospects of domestic and foreign research: standing on the shoulders of giants

With the advancement of science and technology and changes in market demand, the research on anti-yellowing agents is also continuing to deepen and develop. Let’s learn about the current new developments in this field at home and abroad.

1. Current status of domestic and foreign research

(1) Progress in foreign research

Developed countries in Europe and the United States started early in the field of anti-yellowing agents and have formed a relatively complete theoretical system and technical platform. exampleFor example, the Tinuvin series light stabilizers launched by BASF, Germany, have won wide recognition in the global market for their excellent performance. DuPont, the United States, has made many breakthroughs in functional polymer additives and has developed a variety of new anti-yellowing agent products.

(2) Domestic research progress

In recent years, my country has also made great progress in the research on anti-yellowing agents. The Institute of Chemistry, Chinese Academy of Sciences has successfully synthesized several high-performance anti-yellowing agents with independent intellectual property rights, and some products have been industrialized. In addition, universities such as Tsinghua University and Zhejiang University are also actively carrying out relevant basic research, providing strong support for promoting the development of the industry.

2. Development trend prospect

In the future, the development of anti-yellowing agents will show the following directions:

Green and environmentally friendly: With the increasing awareness of environmental protection, people are paying more and more attention to the safety and degradability of chemicals. Therefore, the development of low-toxic and pollution-free green anti-yellowing agents will become an important topic.
Multifunctionalization: Single-function anti-yellowing agents are difficult to meet the increasingly complex application needs. Through molecular design and nanotechnology, it will be an inevitable trend to develop a composite anti-yellowing agent that integrates antioxidant, anti-ultraviolet, and antibacterial functions.
Intelligent: With the help of modern sensing technology and big data analysis methods, the precise control of anti-yellowing agent dosage and real-time monitoring of performance will further improve product quality and economic benefits.

6. Conclusion: Protect your winter fashion

Although the anti-yellowing agent in the sole is inconspicuous, it plays an indispensable role in ensuring the beauty and durability of snow boots. Whether you are strolling on snowy paths or walking through bustling city streets, a pair of snow boots that look like new colors can always add a bit of confidence and style to you. Let us thank these silently dedicated “invisible guards” and let them continue to accompany us through every cold and beautiful winter!