Application of polyurethane shoe anti-yellowing agent in the production of military shoes

1. Introduction: From "Kung Fu on the Foot" to Empowering Technology

Shoes are one of the indispensable inventions in the history of human civilization. From early animal skin wrapping to the application of modern high-tech materials, the development history of shoes has witnessed human continuous pursuit of comfort, functionality and aesthetics. In many fields, military shoes, as a representative of special uses, have far exceeded ordinary civilian shoes. They not only need excellent wear resistance, water resistance and slip resistance, but also meet the stability needs of long-term storage and use. However, during actual use, military shoes often turn yellow due to environmental factors or material aging, which not only affects the appearance, but also may reduce the physical properties of the shoe material.

The problem of yellow change is like an uninvited guest, sneaking into the world of shoe materials, causing many troubles to the production and use of military shoes. Especially in soles or linings made of polyurethane (PU) materials, the molecular structure may change due to ultraviolet irradiation, oxygen oxidation or high temperature, resulting in the color gradually turning yellow or even darkening. This change not only destroys the overall visual effect of military shoes, but may also trigger soldiers’ doubts about their quality, which in turn affects morale and combat efficiency.

To solve this problem, anti-yellowing agents came into being. It is like an invisible protective barrier, which can effectively delay or inhibit the occurrence of yellowing, ensuring that the shoe material still maintains its original color and performance after long-term storage and use. This article will conduct in-depth discussions on the application of polyurethane shoe anti-yellowing agent in military shoes production, from product parameters, mechanism of action to current research at home and abroad, and strive to fully demonstrate the importance of this key technology and its future development direction.

2. Basic concepts and classifications of anti-yellowing agents for polyurethane shoes

(I) What is an anti-yellowing agent?

Anti-yellowing agent is a chemical additive specially used to prevent or slow down the yellowing of materials. Its main function is to prevent or delay the material's photochemical reaction or thermal oxygen aging by capturing free radicals, absorbing ultraviolet rays or neutralizing acidic substances, thereby protecting the material's original color and physical properties. For military shoes, the effect of anti-yellowing agent is particularly important because it directly affects whether the shoe material can remain stable under extreme conditions for a long time.

(II) Classification of anti-yellowing agents

Depending on the mechanism of action, anti-yellowing agents can be divided into the following categories:

Among them, light stabilizers and free radical capture agents are two commonly used types, especially in polyurethane shoe materials. For example, UV absorbers can effectively shield ultraviolet radiation, while hindered amine antioxidants are good at capturing free radicals. The synergistic effect of the two can significantly improve the anti-yellowing ability of shoe materials.

(III) Why do polyurethane shoes need anti-yellowing agents?

Polyurethane (PU) is a polymer polymer that is widely used in shoe material manufacturing for its excellent elasticity, wear resistance and flexibility. However, PU materials themselves have certain photosensitivity and thermal sensitivity, which are prone to molecular chain breakage or cross-linking reactions under light or high temperature environments, resulting in yellowing of color or even degradation of performance. Therefore, adding appropriate anti-yellowing agents to the production of military shoes can not only extend the service life of the shoe material, but also improve the overall quality and reliability.

3. Analysis of product parameters of polyurethane shoe anti-yellowing agent

In order to better understand the practical application effect of anti-yellowing agents, we take a typical product as an example to analyze its key parameters and their significance in detail.

(I) Basic Product Information

(II) Detailed explanation of technical indicators

1. Chemical composition
   The core component of this anti-yellowing agent is a benzotriazole compound, which is an efficient ultraviolet absorber that can selectively absorb ultraviolet rays in the wavelength range and convert its energy into harmless heat to release it, thereby avoiding the yellowing of PU materials due to ultraviolet irradiation.

2. Add ratio
   The addition ratio directly affects the anti-yellowing effect and cost control. It is generally recommended to control it between 0.5% and 1.0%, which can not only ensure sufficient protection performance without adding too much cost burden. The specific dosage needs to be optimized and adjusted according to the actual production process and target performance.

3. Thermal Stability
   The production process of military shoes usually involves higher temperature conditions, such as injection molding or vulcanization. Therefore, anti-yellowing agents must have good thermal stability in order to not decompose or fail during the processing process. This product can remain stable below 280℃, fully meeting the process requirements of military shoes production.

4. Anti-yellowing index
   The anti-yellowing index is an important indicator for measuring the performance of anti-yellowing agents and is evaluated by ASTM D6294 standard testing method. The lower the value, the better the anti-yellowing performance. The anti-yellowing index of this product is ≤3, indicating that it performs well in practical applications and can effectively delay the occurrence of yellowing.

IV. The mechanism and actual effects of anti-yellowing agent

(I) Analysis of the mechanism of action

The reason why anti-yellowing agents can work is mainly due to their unique molecular structure and chemical properties. Here are some common anti-antibodySpecific mechanism of action of yellowing agent:

1. The function of light stabilizer
   The light stabilizer prevents the occurrence of photochemical reactions by absorbing ultraviolet light and converting it into heat. Taking benzotriazole compounds as an example, their molecular structure contains specific functional groups, which can preferentially bind to ultraviolet rays to form a stable intermediate state, and avoid the damage to the PU molecular chain by ultraviolet rays.

2. The role of free radical capture agent
   The main task of free radical capture agents is to capture free radicals generated during material aging, interrupting the propagation of chain reactions. For example, hindered amine antioxidants convert them into stable molecules by providing electrons to free radicals, thereby terminating further oxidation processes.

3. The function of acid neutralizer
   Acid neutralizers focus on neutralizing acidic substances produced by degradation within the material, preventing these acidic substances from catalyzing other chemical reactions and causing the yellowing to worsen. Common acid neutralizers include calcium carbonate and aluminum hydroxide.

(II) Actual effect display

Through experimental comparison, we can clearly see the significant effect of anti-yellowing agents in the production of military shoes. The following is a typical set of experimental data:

It can be seen from the table that after the addition of anti-yellowing agent, the appearance and physical properties of military shoes have been significantly improved. Even after a long period of UV exposure, the color changes in the experimental group are still very slight, and the tensile strength and wear resistance are effectively protected.Keep.

5. Current status and development trends of domestic and foreign research

(I) Progress in foreign research

In recent years, European and American countries have achieved many breakthrough results in the field of anti-yellowing agents. For example, BASF, Germany has developed a new composite anti-yellowing agent that integrates the functions of UV absorbers and free radical capture agents, which can provide comprehensive protection in extreme environments. In addition, DuPont, the United States is also exploring the application of intelligent anti-yellowing agents, using nanotechnology to enhance the dispersion and durability of materials.

(II) Current status of domestic research

In China, with the acceleration of the pace of modernization of military equipment, the research and application of anti-yellowing agents are also receiving increasing attention. The Institute of Chemistry, Chinese Academy of Sciences has successfully developed a highly efficient anti-yellowing agent based on rare earth elements, and its performance has reached the international leading level. At the same time, some private enterprises have also actively invested in R&D and launched a series of cost-effective products to meet different levels of needs.

(III) Future development trends

1. Multifunctional
   The next generation of anti-yellowing agents will develop in a multifunctional direction, not only having anti-yellowing properties, but also improving the material's weather resistance, flame retardancy and antibacterial properties.

2. Green and environmentally friendly
   With the increasing awareness of environmental protection, the development of non-toxic, harmless and easily degradable anti-yellowing agents will become an important trend.

3. Intelligent design
   Combining artificial intelligence technology and big data analysis, accurate formula design and performance prediction of anti-yellowing agents can be achieved, further enhancing its application value.

6. Conclusion: Make every step more solid and reliable

As one of the key equipment to ensure soldiers' mobility and combat effectiveness, military shoes directly affect the success of the entire military operation. The application of anti-yellowing agent for polyurethane shoes has injected new vitality into the performance improvement of military shoes. Through scientific selection and rational use of anti-yellowing agents, we can not only solve the problem of yellowing, but also greatly extend the service life of the shoe material, reduce maintenance costs, and provide strong support for military logistics support.

As an old saying goes, "A journey of a thousand miles begins with a single step." Whether in peacetime or wartime, a pair of high-quality military shoes are a reliable partner for soldiers. The anti-yellowing agent is the invisible guardian behind this reliability. Let us look forward to this technology continuing to play a greater role in the future and contributing more strength to the national defense cause!

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