In the production of plastic products, rubber materials, and various foam products, chemical foaming agents AC play an indispensable role. It can create rich bubble structures within originally dense materials, endowing the product with unique properties such as lightweight, insulation, and buffering.
Chemical properties
The chemical formula ₂ AC foaming agents is C ₄ H ₄ N ₂ O, and their unique molecular structure includes special functional groups such as nitrogen-nitrogen double bonds and carbonyl groups. This structure endows it with special chemical properties: AC foaming agents exhibit relatively good stability at room temperature and pressure, allowing for safe storage and transportation. However, when temperatures rise to a specific range or are stimulated by certain chemicals or mechanical forces, they release large amounts of gas, primarily nitrogen, carbon monoxide, and carbon dioxide. Among these, nitrogen is stable and ensures the stable existence of bubble structures; carbon monoxide and carbon dioxide play crucial roles in gas expansion during the foaming process. The decomposition temperature of AC foaming agents typically ranges from 195-210°C, but this temperature range can be flexibly adjusted by adding different types and proportions of additives to meet the needs of various materials and processing techniques.
Physical properties
From an appearance standpoint, AC foaming agent appears as a powder ranging from pale yellow to white, with a fine texture and no odor. In terms of solubility, it is insoluble in water, making it less likely to dissolve easily in some aqueous systems and affecting its performance; however, it can partially dissolve in organic solvents like dimethyl sulfoxide, a characteristic that is significant in certain special preparation processes. Notably, the particle size and distribution of AC foaming agent particles significantly affect their foaming performance. Generally, the smaller the particle size, the easier it is to evenly disperse in the material, resulting in finer pores. Conversely, the narrower and more uniform the particle size distribution, the better the size and structural consistency of the final product's pores, thereby enhancing its overall performance. For example, when preparing high-end sports shoe soles, it is necessary to use AC foaming agents with small particle size and uniform distribution to achieve good elasticity and shock absorption.
Application fields
AC foaming agents have found widespread application in numerous industries due to their outstanding foaming performance. In the plastic industry, it is a crucial additive for manufacturing shoe soles, soundproof boards, decorative panels, and other products. For example, in shoe sole production, adding AC foaming agent significantly reduces the density of plastic soles, making them lighter while enhancing cushioning performance, thereby providing a comfortable experience for wearers. In soundproofing, AC foaming agent effectively blocks sound. In the rubber industry, AC foaming agents are commonly used to produce sponge rubber products such as automotive interiors and seals. It can make rubber materials soft and elastic, meeting the requirements for flexibility and sealing of different products. Furthermore, AC foaming agents also play a crucial role in the production of building insulation materials, packaging foam, and other products, endowing them with excellent insulation and shock absorption properties to facilitate people's lives and production.
Raw materials required for the production of chemical blowing agent AC
Main raw materials
•Urea: As an important nitrogen-containing raw material in the production of AC foaming agents, urea provides essential nitrogen for its molecular structure. During production, the purity of urea is extremely high because impurities such as urea can interfere with the reaction process, leading to incomplete reactions and thereby reducing the purity and quality of the product. To ensure the purity of urea, recrystallization and other purification methods are typically used to remove impurities and meet production requirements. Only high-purity urea can smoothly participate in chemical changes in subsequent reactions and produce high-quality AC foaming agents.
•Cyanuric Chloride: In the preparation reaction of AC foaming agents, cyanuric Chloride plays a crucial role in constructing the product's framework structure. Its quality stability has a direct impact on the purity and performance of the final product. If cyanide uric chloride deteriorates due to moisture, its chemical activity will change, slowing down the reaction rate and potentially producing unqualified products. Therefore, when storing and using cyanide uric chloride, strict control over environmental humidity is essential to ensure its stable quality. Before production begins, it also needs to be dried to ensure that the moisture content meets the reaction requirements.
Additives and Catalysts
•Additives: To further optimize the performance and processing characteristics of AC foaming agents, auxiliary materials are often added during production. For example, the addition of lubricants can improve the dispersion of AC foaming agents during processing, preventing aggregation and enhancing consistency in foaming effects; colorants can be adjusted according to customer needs, such as in the production of colored packaging foams.
•Catalysts: Certain metal salts or organic acids play a crucial role in the production of AC foaming agents. They can reduce the activation energy of reactions, opening up a "green channel" for chemical reactions that would otherwise require harsh conditions such as high temperature and pressure, allowing them to proceed rapidly under relatively mild conditions. This not only saves energy consumption but also reduces potential side effects from high temperatures and pressures, thereby improving product yield and quality. For example, in certain production processes, using zinc salts as catalysts can significantly accelerate reaction rates while ensuring the stability of AC foaming agents.
Step-by-step production process for chemical AC blowing agents
Preparation of reactants
Before formally initiating the synthesis reaction of AC foaming agents, it is crucial to conduct rigorous screening and meticulous pretreatment of the two main raw materials, urea and cyanide. First, urea needs to be purified through recrystallization. The specific procedure involves dissolving urea in an appropriate solvent, then controlling the temperature and evaporation rate to recrystallize and precipitate it. During this process, impurities such as urea remain in the solution, thereby achieving urea purification. For cyanide uric chloride, drying treatment typically involves using hot air drying or vacuum drying to reduce its moisture content to a level that meets the reaction requirements, thereby avoiding adverse effects of moisture on the reaction. After completing the preprocessing, urea and cyanide need to be mixed using high-precision weighing equipment in precise chemometric proportions. The mixing process should be thoroughly uniform to ensure that subsequent reactions proceed smoothly and consistently, laying the groundwork for producing high-quality AC foaming agents.
Reaction process
Carefully pour the mixed reactants into a reactor equipped with a stirring device and a precise temperature control system. In the reactor, under specific temperature conditions (typically controlled between 80-120°C) and pressure, urea first undergoes a condensation reaction with cyanide. This reaction process is relatively complex, involving multiple intermediate steps where functional groups in urea and cyanide chromide molecules interact, gradually connecting to form a series of intermediate products. As the reaction continues, these intermediate products undergo further cyclization, oxidation, and other reactions, undergoing a series of complex chemical changes that ultimately form AC foaming agents. Throughout the entire reaction process, precise control over temperature, pressure, and reaction time is crucial for ensuring smooth operation and product quality. If the temperature is too high, the AC foaming agent may decompose prematurely during the reaction, not only reducing the product's yield but also affecting its performance; conversely, if the temperature is too low, it can lead to a slow or even incomplete reaction. Similarly, fluctuations in pressure can alter the chemical equilibrium of the reaction, affecting the production and conversion of intermediate products, which in turn impacts the quality of the final AC foaming agent. Therefore, operators need to closely monitor all parameters within the reactor and make timely adjustments based on actual conditions to ensure that the reaction proceeds under optimal conditions.
Separation and Purification
After the reaction, the reactor contains a complex mixture of AC foaming agents, unreacted raw materials, and various byproducts. To obtain high-purity AC foaming agent products, a series of separation and purification operations are required. First, by filtering, the solid substance is separated from the liquid to initially obtain a filter cake containing AC foaming agent. Then, further impurities were removed using recrystallization methods. Based on the difference in solubility of AC foaming agent and impurities in different solvents, choose an appropriate solvent to dissolve the filter cake. Then, by controlling temperature and solvent evaporation rate, the AC foaming agent recrystallizes while the impurities remain in the solution. After multiple recrystallization operations, the purity of the AC foaming agent can be effectively improved. Finally, the AC foaming agent obtained through recrystallization was dried to remove any residual solvents and moisture. The drying method can be chosen as hot air drying, vacuum drying, or freeze-drying based on actual conditions, ensuring that the final AC foaming agent product has good stability and quality.
Quality Control and Testing
To ensure that the produced AC foaming agents meet market and customer needs, they must undergo rigorous quality control and comprehensive testing. In purity testing, high-performance liquid chromatography (HPLC) technology is typically used. HPLC can precisely separate and detect various components in AC foaming agents. By comparing them with standard samples, it can accurately determine the purity of the product to ensure it meets quality standards. For testing decomposition temperature and exhaust volume, thermogravimetric analyzers (TGAs) are commonly used detection equipment. TGA can monitor in real time the quality changes of AC foaming agents during heating under programmed temperature conditions, thereby determining their decomposition temperature and release volume, and evaluating their foaming performance. Furthermore, laser particle size analyzers can detect the particle size distribution of AC foaming agent particles, understand their particle size and uniformity, and provide important references for product applications. Only when all indicators of the AC foaming agent meet strict quality standards can it be deemed a qualified product for market sale.
Safety precautions for chemical foaming agent AC production
Management of Hazardous Chemicals
During the production of AC foaming agents, raw materials such as urea and cyanide, as well as intermediate and by-products that may arise during the reaction, often exhibit certain corrosive and toxic properties. Therefore, operators must strictly adhere to safety operating procedures when storing and using these hazardous chemicals, wear protective gloves, masks, and goggles, and avoid direct contact. For warehouses storing hazardous chemicals, it is important to maintain good ventilation, install fire-resistant, explosion-proof, and leak-proof safety facilities, and conduct regular inspections and maintenance. As soon as a chemical leak occurs, it must be cleaned up and disposed of immediately according to standard emergency procedures to prevent harm to the environment and personnel.
Environmental protection
The production process of AC foaming agent generates a certain amount of wastewater, exhaust gases, and slag, which can cause severe environmental pollution if not properly treated and discharged directly. Wastewater may contain unreacted raw materials, byproducts, and some chemical additives that are toxic and corrosive, contaminating water bodies and soil; gases produced during reactions, such as carbon monoxide and hydrogen chloride, can also have adverse effects on the environment if not properly disposed of. Using green production processes to reduce pollutant generation at its source is an inevitable choice for achieving sustainable development and a social responsibility that enterprises should fulfill.
Compared to physical foaming agents, AC foaming agents have clear advantages. Physical foaming agents primarily introduce bubbles into materials through mechanical stirring and compressed gases, resulting in relatively limited gas output and often insufficiently dense bubble structures. And during the decomposition process, AC foaming agents produce a large amount of gas, resulting in a larger gas output. This allows them to form richer and finer bubble structures within the material, thereby enhancing the product's performance. For example, when producing high-performance foam plastics, using AC foaming agents can reduce the product's density and increase its strength while offering better insulation and soundproofing. Compared to other chemical foaming agents, AC foaming agents have a wider decomposition temperature range, making them suitable for various processing techniques and materials. Whether it's injection molding, extrusion, or molding, AC foaming agents can produce excellent foaming results. Additionally, in terms of price, AC foaming agents are relatively affordable and offer good value for money, making them highly competitive in the market and widely used by customers in the industry who have a demand for foaming agents.
