Application of anti-yellowing agent for shoe material in winter warm shoes manufacturing

Application of shoe material anti-yellowing agent in winter warm shoes manufacturing

1. Preface: The secret weapon to keep shoes "youthful forever"

The coldness of winter can always make people feel infinite desire for warmth. A pair of high-quality winter warm shoes is undoubtedly a good companion to resist the severe cold. However, while pursuing comfort and warmth, many people ignore a question - will shoes lose their original beauty over time? Especially those shoes that use white or light-colored uppers often experience headaches of "yellow changes" after using them for a period of time. This change not only affects the overall appearance of the shoes, but may also make consumers mistakenly believe that there are problems with product quality.

So, what exactly is "yellow change"? Simply put, it refers to the chemical reaction of certain materials under the action of light, heat or other external factors, causing the originally flawless material to gradually turn yellow or even brown. This is especially common for winter warm shoes, because these shoes usually require soft, lightweight and warm-resistant shoe materials such as EVA (ethylene-vinyl acetate copolymer) foaming materials or PU (polyurethane) sponges. Although these materials have superior performance, their internal structure contains unsaturated bonds or easily oxidized components, making them prone to yellowing when exposed to ultraviolet rays, oxygen or high-temperature environments for a long time.

In order to solve this problem, anti-yellowing agents in shoe materials emerged. This is a functional additive designed specifically for the yellowing problem of shoe materials. It can effectively delay or prevent the occurrence of yellowing without affecting the original performance of the material. Through scientific and reasonable application, anti-yellowing agents can not only improve the appearance of winter warm shoes, but also enhance consumers' purchasing confidence and brand loyalty.

This article will start from the basic principles of anti-yellowing agents, combine relevant domestic and foreign literature to deeply explore its specific application methods and effect evaluation in winter warm shoes manufacturing, and present readers with easy-to-understand language with rich tabular data.

2. Basic knowledge of anti-yellowing agent for shoe material

(I) Definition and mechanism of action

Shoe material anti-yellowing agent is a functional chemical that is mainly used to prevent the yellowing of the shoe material due to environmental factors. Its core function is to protect the shoe material from oxidative degradation by inhibiting free radical chain reactions or capturing harmful substances in photochemical products. In other words, the anti-yellowing agent is like an invisible "protective shield", firmly protecting the pure nature of the shoe material.

From the perspective of mechanism of action, anti-yellowing agents are mainly divided into two categories:

Antioxidation-type anti-yellowing agent
This type of anti-yellowing agent prevents further aging of the material by capturing free radicals and interrupting the oxidation reaction chain. They usually contain phenols or aminesCompounds such as BHT (2,6-di-tert-butyl-4-methylphenol) and hindered amine antioxidants (HALS). These compounds can effectively reduce ultraviolet irradiation and molecular cleavage under high temperature conditions.
UV Absorbent Anti-Yellowing Agent
This type of anti-yellowing agent focuses on shielding the effects of ultraviolet rays. They can absorb UV energy at a specific wavelength and convert it into harmless thermal energy to release it, thus avoiding photochemical reactions caused by UV. Common UV absorbers include benzotriazoles, salicylates and benzophenone compounds.

The two types of anti-yellowing agents have their own advantages, and the specific choice depends on the characteristics of the target material and the use scenario. For example, for outdoor sports shoes that are often exposed to the sun, UV-absorbent anti-yellowing agents may be a better choice; for indoor home slippers, anti-oxidation anti-yellowing agents are more suitable.

(II) Detailed explanation of product parameters

To better understand the actual performance of anti-yellowing agents, we can compare the key parameters of different types of products through the following table:

parameter name	Antioxidation-type anti-yellowing agent	UV Absorbent Anti-Yellowing Agent
Chemical composition	Phenols, amines	Benzotriazoles, benzophenones
Appearance	White Powder	Light yellow to transparent liquid
Melting point (℃)	80~150	–
Solubilization	Insoluble in water, soluble in organic solvents	Soluble in a variety of organic solvents
Recommended dosage (%)	0.1~0.5	0.3~1.0
Advantages	Low cost, stable effect	Extremely sensitive to ultraviolet rays
Disadvantages	Limited protection against ultraviolet rays	Relatively high cost

It should be noted that in actual applications, the type and dosage of anti-yellowing agents are often required to be adjusted according to the specific circumstances. For example, if the shoe material itself already has a certain antioxidant ability, a lower concentration of anti-yellowing agent can be selected to reduce costs; on the contrary, if the shoe material is susceptible to strong light, the proportion of the ultraviolet-absorbing anti-yellowing agent should be appropriately increased.

(III) Current status of domestic and foreign research

In recent years, with the continuous improvement of consumers' requirements for product quality, the research and development and application of anti-yellowing agents have also made significant progress. The following are some representative research results:

DuPont Research
In its paper "UV Stabilizers in Footwear Materials", DuPont pointed out that adding an appropriate amount of ultraviolet absorber can reduce the yellowing index of EVA sole materials by more than 70%. In addition, they have also developed a new composite anti-yellowing agent that can take into account both antioxidant and UV protection functions, suitable for the high-end sports shoe market.
Technical breakthroughs of Germany's BASF Group (BASF)
In its 2021 annual report, BASF mentioned that they have successfully developed an anti-yellowing agent based on nanotechnology, which has higher dispersion and longer-lasting effects. Experimental data show that the processed PU upper material still maintains its initial color after 90 days of continuous exposure to the sun, and does not show obvious yellowing.
Contributions of the Institute of Chemistry, Chinese Academy of Sciences
Domestic scientific research institutions have also made important contributions in the field of anti-yellowing agents. For example, a study by the Institute of Chemistry, Chinese Academy of Sciences shows that by optimizing the molecular structure of the anti-yellowing agent, its compatibility with the shoe material can be significantly improved, thereby avoiding secondary pollution problems caused by migration or precipitation.

3. Application of shoe material anti-yellowing agent in warm shoes in winter

(I) Characteristics and needs of warm shoes in winter

As an exclusive product for special seasons, winter warm shoes must meet the following requirements:

Excellent warmth performance
Winter warm shoes usually use multi-layer composite structures, with the sole using high-density EVA foaming material, and the upper using PU sponge or imitation sheepskin suede fabric. These materialsNot only is it light and soft, but it also has a low thermal conductivity, which can effectively isolate the cold air outside.
Good comfort
The lining materials of warm shoes in winter usually include antibacterial and anti-odor functions to ensure good hygiene after wearing for a long time. At the same time, the insole part will also be equipped with a breathable hole design to promote the evaporation of sweat on the feet.
Last lasting aesthetic
It is precisely because warm shoes are used frequently in winter and are often exposed to complex environments that their yellowing resistance is put forward higher requirements. Whether it is snow boots or hiking boots, they need to maintain a good appearance while ensuring functionality.

(II) Specific application methods of anti-yellowing agent

The application methods of anti-yellowing agents are also different for different parts of warm shoes in winter. Here are a few typical examples:

Sole material treatment
The soles of warm shoes in winter are mostly made of EVA foaming material. Although this material is flexible, it is prone to yellowing under ultraviolet rays and high temperature conditions. To this end, a certain amount of antioxidant anti-yellowing agent (such as BHT) can be pre-mixed into the EVA raw material and evenly distributed to the entire sole through the injection molding process. According to the experimental results, this method can reduce the yellowing index of the sole by about 60%, and will not affect its physical and mechanical properties.
Upper material modification
The upper material of winter warm shoes is usually made of PU sponge or TPU film. These materials can be coated or impregnated during the production process to introduce ultraviolet-absorbent anti-yellowing agents. For example, a solution containing a benzotriazole compound is uniformly sprayed on the upper and then subjected to a drying and curing process. This not only effectively prevents yellowing, but also improves the wear resistance and scratch resistance of the upper.
Line material optimization
Since the lining material directly contacts the human skin, it has strict requirements on its safety. In this case, food-grade certified anti-yellowing agents (such as natural plant extracts) can be selected to ensure harmless to human health. In addition, nanosilver ion technology can be combined to impart additional antibacterial function to the lining material.

(III) Case Analysis: Successful Experience of a Well-known Brand in Winter Warm Shoes

A internationally renowned sports brand has adopted advanced anti-yellowing technology in its new winter warm shoes, achieving remarkable results. Here are some technical details of this product:

Part	Materials used	Anti-yellowing agent type	Effect Evaluation
Sole	EVA foaming material	Antioxidation anti-yellowing agent (BHT)	The yellowing index is reduced by 65%, and the service life is increased by 30%.
Upper	PU sponge + TPU film	UV Absorbent Anti-Yellowing Agent	Keep the primary color under high-intensity ultraviolet rays
Line	Imitation goatskin velvet fiber	Natural Plant Extract	Safe and environmentally friendly, with antibacterial effects

By finely refining the various components, this winter warm shoe not only always remains bright and new in appearance, but also shows extremely high durability and comfort in actual use, winning wide recognition from the market.

IV. Advantages and limitations of anti-yellowing agents

(I) Summary of Advantages

Extend product life
Anti-yellowing agents can significantly delay the aging speed of shoe materials, thereby extending the overall service life of warm shoes in winter.
Enhance brand image
High-quality anti-yellowing treatment helps to establish the brand's high-end image and attract more loyal users.
Adapting to diverse needs
Different types of anti-yellowing agents can be flexibly matched according to the specific application scenario to meet personalized customization needs.

(II) Localization Analysis

Although anti-yellowing agents bring many benefits, there are still some challenges in their application:

Cost Issues
High-performance anti-yellowing agents are relatively expensive and may increase the manufacturing cost of the product.
Compatibility Limitation
Not all shoe materials are suitable for adding anti-yellowing agents, and some materials may cause adverse reactions due to compatibility issues.
Environmental pressure
Some traditional anti-yellowing agents contain potentially toxic ingredients and may not meet the increasingly stringent environmental regulations.

5. Future development trends and prospects

With the advancement of science and technology and the development of society, the field of anti-yellowing agents in the shoe material is ushering in new opportunities and challenges. Here are some directions worth paying attention to:

Green trend
Develop more anti-yellowing agents based on natural plant extracts or biodegradable materials to meet environmental needs.
Multifunctional Integration
Combine anti-yellowing agents with other functional additives (such as antibacterial agents, fire repellents, etc.) to achieve "one dose and multiple effects".
Intelligent Control
Using sensor technology and big data analysis, we can monitor the degree of yellowing of the shoe material in real time and dynamically adjust the amount of anti-yellowing agent added.

In short, the anti-yellowing agent of shoe material has broad application prospects in winter warm shoes manufacturing. Only by constantly innovating and improving can we truly realize the beautiful vision of "making every pair of shoes young forever"!