Development history of polymer foaming technology
With the continuous progress of materials science and industrial technology, polymer foaming technology has experienced the evolution from simple to complex, from inefficient to efficient. In the early days, polymer foaming mainly relied on primitive methods, and the resulting foam materials have many limitations in terms of performance and quality. Nowadays, advanced manufacturing processes and material innovations have brought new opportunities for polymer foaming, resulting in a wider range of applications for foams in a variety of industries.
The core position of blowing agent in polymer foaming
In the polymer foaming process, the blowing agent plays an indispensable role. It is a key factor in determining the performance, structure and quality of the foam material. High-quality blowing agents are able to generate bubbles uniformly in the polymer matrix, thus forming an ideal foam structure. The type and amount of blowing agent, as well as its decomposition characteristics, can have a profound effect on the density, strength, flexibility and insulation properties of the final foam product.
Among many blowing agents, azodicarbonamide (ADC) has gradually become the favorite in various industrial fields by virtue of its unique performance.ADC can decompose controllably at high temperatures, releasing a variety of gases, which form bubbles in the polymer matrix, providing strong support for the manufacture of foam materials with specific properties.
Foaming agent is a key additive in the preparation of foam, which can form a cell structure in the plastic. According to its action principle, it can be divided into physical blowing agent (PBA) and chemical blowing agent (CBA).
Physical blowing agent is a kind of substance that can volatilize and produce at least one kind of gas as foaming gas in the process. It mainly includes compressed inert gas, soluble sublimation solids and low boiling point volatile liquid three categories, of which low boiling point volatile liquid is most commonly used. The main varieties of low-boiling volatile liquids are aliphatic hydrocarbons (hydrocarbons containing 5 to 7 carbons), halogenated hydrocarbons (fluorine, chlorine substitutes), and other low-boiling alcohols, ethers, ketones and aromatics, etc. These substances volatilize rapidly when heated. These substances will evaporate rapidly when heated, forming bubbles in the polymer matrix, thus realizing foaming.
Chemical blowing agent is thermally decomposed during processing to produce at least one foaming gas (such as N ₂, CO ₂, etc.) of the substance, can be further divided into inorganic chemical blowing agent and organic chemical blowing agent.
1. Inorganic chemical blowing agent
Inorganic chemical blowing agent is the first type of chemical blowing agent used. However, it has some obvious disadvantages. For example, poor compatibility with resins, low decomposition temperature, and the gases produced by decomposition (e.g., NH₃ and CO₂, etc.) are easy to penetrate the bubble film, which greatly restricts its application in plastics. In actual production, inorganic chemical blowing agents are generally not used alone, but often used in conjunction with organic chemical blowing agents for plastics processing. Common inorganic chemical blowing agents are sodium bicarbonate, ammonium bicarbonate, ammonium carbonate, sodium nitrite and sodium borohydride.
2. Organic chemical blowing agent
Organic chemical blowing agent is currently the most widely used type of blowing agent. It has good dispersion in the resin, the decomposition temperature range is narrower, and the resulting gas is not easy to escape from the bubble hole. Common organic chemical blowing agents include azo, nitroso, sulfonyl hydrazine and so on. Among them, azo class is the most commonly used organic chemical blowing agent, and in the azo class, azodicarbonamide (AC) is the most widely used. the decomposition temperature of AC can be adjusted by the foaming accelerator, and it can be adjusted to the range of 150 - 205 ℃ in general. Nitroso foaming agent is the second largest foaming agent category after azo.
Application in the field of plastics
1. Principle as a foaming agent
Azodicarbonamide (ADCA) is mainly used as a foaming agent in the field of plastics. Under high temperature conditions, it undergoes decomposition reaction to produce gases such as nitrogen, carbon monoxide, carbon dioxide and ammonia. These gases form gas bubbles in the polymer matrix, which in turn form a porous structure and allow the plastic to foam.
2. Applicable types of plastics
It is mainly used for foaming polyvinyl chloride, polyethylene, polypropylene, polyamide, polystyrene, ABS resin and many other plastics. For plastics such as PP, PA, PC, PET/PBT, etc., whose injection temperature is higher than 230°C, a modified azodicarbonamide blowing agent can be added. After adding, the fluidity of the molten plastic is enhanced, which ensures that every part of the plastic is heated uniformly and effectively prevents the plastic products from warping and deformation.
Application in the rubber industry
1. Foaming mechanism
In the rubber industry, azodicarbonamide (ADC) is also widely used as a foaming agent, especially in the production of foam rubber products such as seals, gaskets, mats and carpets, etc. ADC decomposes at high temperatures, releasing nitrogen gas, which forms bubbles in the rubber matrix, resulting in a honeycomb structure.
2. Advantages over other blowing agents
ADC has many advantages over other blowing agents. Its lower cost, can realize the foaming effect with lower input; high gas yield, can form a large number of bubbles in the rubber matrix; uniform distribution of bubble holes, can make the structure of rubber foam more stable; good compatibility with rubber compounds, will not affect the original performance of rubber. It is mainly used for foaming of neoprene rubber, nitrile rubber, natural rubber, butyl rubber, styrene-butadiene rubber, silicone rubber and other rubbers. Its decomposition products are non-toxic, odorless and non-polluting, and can obtain pure white rubber foam.
Specific application examples of azodicarbonamide
1. Artificial leather
In PVC or PU artificial leather coated with modified azodicarbonamide foam, can give artificial leather suede-like touch. By properly adjusting the amount and particle size of the modified azodicarbonamide blowing agent, other surface effects can also be realized. In addition, it can make the artificial leather become soft, elastic and breathable, which improves the quality and use experience of the artificial leather.
2. wallpaper
Adding modified azodicarbonamide blowing agent in the production of wallpaper can make the wallpaper show three-dimensional pattern effect or velvet texture. The use of different particle sizes produces different types of surface appearance and feel. Usually, small particle size foaming agent will bring a smooth surface, while large particle size foaming agent will make the surface relatively rough, to meet the diversified needs of different consumers on the appearance of wallpaper.
3. Printing paste
Adding modified azodicarbonamide foaming agent to printing ink can not only maintain the beauty and durability of the printed materials, but also bring different types of tactile sensation, such as realizing 3D effect printing. At the same time, the inks / pastes have good adhesion, are not easy to peel off, and have high color saturation with good hiding power. Through customized design, low / medium / high suede type, different foaming degree and temperature resistance degree of product effect can be realized, which enriches the diversity of printed products.
4. Shoe soles
Conventional sole materials are often bulky and prone to cracking and abrasion. The use of modified azodicarbonamide foamers not only shortens the curing time of the sole, making it easier to mold, but also reduces the weight of the sole, making it more comfortable for the wearer. The controlled foaming process reduces defects in the sole and improves product yield. The surface of the modified soles has a matte rubber texture, brighter color and more beautiful appearance.
The importance of foaming agent in polymer foaming
The key factors determining the effect of foaming
The success of polymer foaming depends largely on the choice of blowing agent. Foaming agent is the core material to form bubbles in the polymer matrix, and its performance directly affects the size, number and distribution of bubbles. The right blowing agent is able to generate bubbles uniformly in the polymer matrix, thus forming a desirable foam structure. If the blowing agent is not properly selected, it may lead to uneven bubble size, rupture of the bubble holes or failure to form an effective foam structure, which will seriously affect the quality of the foam product.
Influence on the performance of foam materials
The type and dosage of blowing agent will have a profound effect on the final performance of the foam material. For example, by adjusting the concentration of the blowing agent, the density of the foam can be controlled to meet the specific requirements for foam density in different industrial fields. At the same time, the blowing agent can also affect the structure of the foam and the size of the pores, which in turn optimizes the strength, flexibility and thermal insulation properties of the foam material. In the field of building thermal insulation, the foam material is required to have good thermal insulation performance, at this time it is possible to adjust the foam structure by choosing the appropriate blowing agent to improve its thermal insulation effect.
The prominence of azodicarbonamide (ADC)
Among many foaming agents, ADC occupies a prominent position in various industrial applications by virtue of its unique performance. It has good decomposition characteristics, is able to release gases at the right temperature, and its decomposition process can be precisely controlled by additives. This makes it possible to accurately adjust the various properties of the foam according to the actual needs in the production process and to meet the manufacturing requirements of different products.
Influence of ADC on physical and mechanical properties of foam
Influence of ADC concentration on foam density
1. Direct correlation between density and concentration
There is a direct correspondence between the density of foam and the concentration of ADC. When the concentration of ADC is increased, the amount of gas produced by decomposition in the polymer matrix increases, resulting in the formation of more bubbles, which leads to the expansion of the volume of the foam and a decrease in density. On the contrary, when the concentration of ADC is decreased, the amount of gas produced decreases and the density of the foam increases accordingly.
2. Meeting diverse industrial needs
By precisely fine-tuning the concentration of ADC, manufacturers are able to produce foams with specific density requirements to meet the diverse needs of different industries. In the packaging industry, in order to protect fragile goods, often need low density, good cushioning performance of the foam material, this time can be appropriate to increase the concentration of ADC to reduce the density of the foam; and in some of the higher requirements of the structural strength of the application, the need for higher density of the foam, can be realized by reducing the amount of ADC.
Adjustment of foam structure and pore size with ADC
1. Ability to regulate foam structure
ADC gives manufacturers the ability to effectively control the foam structure and cell size. In the foaming process, by adjusting the decomposition rate and dosage of ADC, as well as cooperating with other additives, the nucleation and growth process of bubbles can be changed, so as to realize the fine control of foam structure. For example, when the decomposition rate of ADC is controlled to be slower, the bubbles have more time to grow and merge, and a foam structure with larger vesicles may be formed; whereas accelerating the decomposition rate of ADC will lead to the rapid formation of bubbles, which will result in smaller and more numerous vesicles.
2. Optimizing foam properties for different applications
This flexibility in foam structure and cell size allows manufacturers to tailor the foam to optimize its properties for different application scenarios. In the aerospace field, the foam material needs to be characterized by high strength and light weight, at this time, it is possible to control the parameters of ADC to prepare a foam with small holes and uniform structure to improve its strength-to-weight ratio; in the field of sound insulation, the foam structure with larger holes may be more conducive to absorbing sound, and by adjusting the use of ADC, it is possible to produce a foam product that meets the demand for sound insulation.
In the AC blowing agent supply market in China, Shun Tai Technology stands out. Shun Tai Technology specializes in the research and development and production of AC blowing agents with advanced production technology and strict quality control system. Its AC blowing agents are of stable quality and excellent performance, and can meet the needs of different customers in polymer foaming applications. Whether in the field of plastics, rubber, artificial leather, wallpaper and other industries, Shun Tai's AC blowing agent has won wide recognition from customers for its excellent performance, and has played an important role in promoting the development of China's polymer foaming industry.
