Intro
Blowing agents play a vital role in modern industrial production. From our daily use of plastic products to insulation materials in the construction industry, blowing agents are used everywhere. Among them, TSH blowing agents are gradually attracting attention from many industries due to their unique properties and advantages. TSH foaming agents show great potential for improving the thermal insulation properties of products as well as the lightweight properties of materials.
Chemical composition
TSH foaming agents are specially formulated chemical agents. Its main components include organic foaming agents and inorganic additives. Organic foaming agents are usually compounds, such as azodicarbonamide (ADC), that decompose under certain conditions to produce gases. These compounds, when heated or subjected to other excitation conditions, undergo a decomposition reaction that releases gases such as nitrogen and carbon dioxide, which causes the material to produce a foam structure. Inorganic additives, on the other hand, play a role in stabilizing the foam structure, regulating the foaming rate, and improving the compatibility of the blowing agent with the base material. Common inorganic additives include calcium carbonate and talc. These components work together to optimize the foaming effect of TSH blowing agents in different application scenarios.
Principle of operation
The working principle of TSH blowing agents is based on a dual physical and chemical process. When the TSH blowing agent is mixed with the base material (e.g. plastic, rubber, etc.) and subjected to specific conditions, the organic blowing agent starts to decompose. In the case of azodicarbonamide, for example, when heated to a certain temperature (usually between 150 - 200°C, depending on its purity and other components of the formulation), it undergoes a decomposition reaction that produces gases such as nitrogen and carbon dioxide. These gases form tiny bubble nuclei in the base material. As the reaction progresses, the bubble nuclei absorb the gases and grow, eventually forming a uniformly distributed foam structure within the material. Meanwhile, inorganic additives play an important supporting role in this process. They can be adsorbed on the bubble wall to increase the strength of the bubble wall and prevent the bubbles from rupturing or merging during the growth process, thus ensuring the stability and uniformity of the foam structure.
Common types
TSH blowing agents can be categorized into a variety of types depending on the application requirements and formulation design. In terms of foaming temperature range, there are low temperature type TSH blowing agents and high temperature type TSH blowing agents. Low temperature type TSH blowing agents are suitable for processing of temperature sensitive materials, such as foam molding of certain soft plastics, where the foaming temperature is generally in the range of 100 - 150°C. This type of blowing agent can be used in a wide range of applications and formulations. This type of blowing agent can decompose quickly at relatively low temperatures to produce gases, avoiding degradation or changes in material properties at high temperatures. High-temperature TSH blowing agents, on the other hand, are suitable for materials that need to be processed at higher temperatures, such as the injection molding of certain engineering plastics, where foaming temperatures are typically in the range of 200 - 250°C or even higher. In addition, TSH blowing agents can be categorized into powdered TSH blowing agents and granular TSH blowing agents based on the form of the blowing agent. Powdered TSH blowing agents have a large specific surface area and can be dispersed more homogeneously when mixed with the base material, making them suitable for production processes that require high mixing homogeneity. Granular TSH blowing agents have better flowability and are more convenient for use in more automated production lines such as continuous extrusion molding processes.
Pre-use preparation
Safety precautions
Strict safety precautions must be observed before using TSH blowing agents. Since some of the components in TSH blowing agents can be potentially hazardous to human health and the environment, operators are required to wear appropriate personal protective equipment (PPE). First, protective eyewear should be worn to prevent the blowing agent powder or tiny particles generated during decomposition from entering the eyes and causing irritation or injury. Second, protective masks should be worn to avoid inhaling harmful gases or dust produced by the decomposition of the blowing agent. If you may come into contact with the blowing agent during operation, you should also wear chemical protective gloves to prevent skin contact from causing allergies or other adverse reactions. In addition, the operation place should be well ventilated, and ventilation equipment should be installed to discharge the gas produced by decomposition in time to reduce the concentration of harmful gases in the working environment.
Preparation of equipment and tools
The use of TSH blowing agent requires suitable equipment and tools. For the mixing process, equipment such as a high-speed mixer or twin-screw extruder is usually required. High-speed mixers allow the TSH blowing agent to be thoroughly mixed with the base material in a relatively short period of time, ensuring that the blowing agent is evenly dispersed in the material. When selecting a mixer, the model and power should be determined according to the scale of production and mixing requirements. For large-scale production, it may be necessary to choose a large industrial-grade mixer with the mixing speed and capacity to meet production requirements. Twin-screw extruders, on the other hand, can not only achieve the mixing of blowing agent and base material, but also plasticize and transport the material during the extrusion process, which is suitable for continuous production processes, such as foam molding of plastic plates and pipes. Before using these equipments, it is necessary to carry out a comprehensive inspection and maintenance to ensure that the equipments are running normally, so as to avoid production accidents or product quality problems caused by equipment failure. It is also necessary to prepare some auxiliary tools, such as measuring instruments for accurate weighing of TSH blowing agents and base materials to ensure the accuracy of the formulation.
Material compatibility check
Before using the TSH blowing agent, its compatibility with the base material must be checked. Different types of TSH blowing agents are selective of the base material. For example, for polyvinyl chloride (PVC) materials, a TSH blowing agent with good compatibility needs to be selected. If not properly selected, phase separation between the blowing agent and the PVC material may occur, resulting in uneven or even non-foaming. The compatibility of the materials can be initially determined by some simple experiments. Mix a small amount of TSH blowing agent with the base material and observe its dispersion during mixing and its reaction under certain conditions (e.g. heating to the desired foaming temperature). If lumps or precipitates appear during mixing, or if the desired foaming effect is not produced after heating, it is necessary to consider replacing the blowing agent or adjusting the formulation.
How to use TSH foaming agents?
Measuring and mixing
Accurate measurement of the amount of TSH foaming agent and base material is one of the key steps in the application process. Weighing is done with precise measuring instruments according to the specific production recipe. Generally, the amount of TSH blowing agent to be added to the base material is adjusted according to the performance requirements and foaming effect of the product and is usually in the range of 0.5% - 5% (mass fraction). For example, in the production of lightweight plastic foam products, the addition of TSH blowing agent may be controlled to be around 2% - 3% if high foam multiplication and good thermal insulation properties are desired. The weighed TSH blowing agent and the base material are mixed in the mixing equipment. During the mixing process, control the mixing speed and mixing time. Through thorough mixing, it is ensured that the TSH blowing agent is uniformly dispersed in the base material, which lays a good foundation for the subsequent foaming process.
Application process
Injection molding
When using TSH blowing agent in the injection molding process, the mixed plastic granules containing TSH blowing agent are first added to the hopper of the injection molding machine. The injection molding machine conveys the plastic granules forward by means of a rotating screw, which simultaneously heats and plasticizes them. When the plastic melt reaches a certain temperature and pressure, the injection molding machine injects the melt into the mold cavity. During the injection of the melt into the mold, the plastic melt cools rapidly due to the low temperature of the mold, at which time the TSH blowing agent begins to decompose and produce gases that cause the plastic melt to foam and expand in the mold cavity, forming a plastic product with a foam structure. During this process, parameters such as injection temperature, injection pressure and injection speed need to be precisely controlled. In general, the injection temperature is determined by the plastic material used and the type of TSH blowing agent, and is usually in the range of 180 - 250°C. The injection pressure and the injection speed are determined by the temperature of the mold. The injection pressure and injection speed affect the filling of the plastic melt in the mold cavity and the foaming effect. A higher injection pressure ensures better filling of the mold cavity with plastic melt, but too high a pressure may inhibit the foaming effect of the blowing agent; while a suitable injection speed allows for uniform distribution of the plastic melt in the mold cavity, while providing the right time and space for the decomposition of the blowing agent.
Extrusion Molding
For the extrusion molding process, such as the production of plastic pipes, plates, etc., the mixed materials are added to the extruder through a hopper. The screw of the extruder conveys, compresses and plasticizes the material as it rotates. As the material moves through the screw, the temperature gradually rises, and when the decomposition temperature of the TSH blowing agent is reached, the blowing agent begins to decompose and produce gas. When the material is extruded at the mouth die of the extruder, the gas expands rapidly due to the sudden decrease in pressure, causing the extruded material to form a foam structure. In the extrusion molding process, the temperature distribution of the extruder, screw speed and traction speed and other parameters should be controlled. The temperature distribution of the extruder should be set according to the characteristics of the material and foaming requirements, generally divided into several heating zones, from the feeding section to the mouth of the mold section, the temperature gradually increases. The screw speed affects the residence time of the material in the extruder and the mixing effect, usually between 10 - 100 rpm. The haul-off speed is matched to the extrusion speed to ensure dimensional accuracy and foam uniformity of the extruded product.
Spraying applications
TSH blowing agent can be applied by spraying in special application scenarios, e.g. foaming of existing surfaces to increase thermal and acoustic insulation properties. First, the TSH blowing agent is mixed with a suitable solvent or carrier to form a sprayable foam. Then, spraying equipment is used to evenly apply the foaming liquid to the surface of the object. During the spraying process, the spraying pressure and spraying distance should be controlled. Generally speaking, the spraying pressure is between 0.2 - 0.5MPa, and the spraying distance is kept at about 10 - 20cm, which can ensure that the foaming liquid is evenly distributed on the surface of the object. After spraying, under certain temperature and humidity conditions, the TSH blowing agent will decompose and foam on the surface of the object to form a foam layer. In this process, the ambient temperature and humidity have a certain influence on the foaming effect. Generally speaking, a suitable ambient temperature between 20 - 30°C and relative humidity between 40% - 60% will ensure that the blowing agent can decompose smoothly and form a uniform and stable foam structure.
Curing and Post-treatment
After the TSH blowing agent has decomposed in the material to produce a foam structure, a curing process is required to stabilize the foam structure and enable the product to achieve the desired properties. For thermoplastics, curing is usually done by cooling. By lowering the temperature of the product, the plastic melt solidifies and the foam structure is fixed. In the cooling process, can be used in air-cooled or water-cooled and other ways, the specific choice should be based on the size and shape of the products and production efficiency and other factors to decide. For some thermosetting plastics or rubber products, curing may be required by heating or adding curing agent. During the curing process, the curing temperature and curing time should be strictly controlled. If the curing temperature is too high or the curing time is too long, it may lead to a decline in product performance, such as brittle plastic, rubber aging, etc.; while the curing temperature is too low or the curing time is too short, it may not be able to make the product fully cured, which affects its strength and stability. After curing, it is necessary to carry out post-processing of the products, such as trimming, sanding, surface coating, etc., in order to improve the appearance quality and performance of the products.
Excellent foaming properties
TSH foaming agents have excellent foaming properties and produce a uniform and fine foam structure. Compared with some other foaming agents, TSH foaming agents can achieve a higher foaming ratio under the same conditions. For example, in some plastic foamed products, the use of TSH blowing agent can expand the volume of the product by 3 - 5 times or more, thereby effectively reducing the density of the product and realizing the lightweighting of the material. At the same time, the foaming process is relatively easy to control, and the pore size and distribution of the foam can be precisely controlled by adjusting the formulation and process parameters. Smaller pore size can improve the strength and heat insulation performance of the products, while uniform pore size distribution can ensure the consistency of product performance.
Good thermal stability
TSH blowing agent has good thermal stability within a certain temperature range. This enables it to maintain stable properties during high temperature processing without premature decomposition or other undesirable reactions. For example, in the foaming of engineering plastics that require processing at high temperatures of over 200°C, TSH blowing agent is able to remain stable during plasticization and molding of the material and does not begin to decompose and foam until the appropriate temperature is reached. This good thermal stability not only ensures the smooth running of the production process, but also improves the quality and reliability of the product. At the same time, TSH blowing agent is able to maintain the stability of the foam structure within a certain temperature range during the use of the product, and will not cause damage to the foam structure or deterioration in performance due to changes in ambient temperature.
Wide applicability
TSH blowing agents have a wide range of applicability and can be applied to a wide variety of base materials and different production processes. Whether it is thermoplastic plastics (e.g. polyethylene, polypropylene, polystyrene, etc.), thermosetting plastics (e.g. epoxy resins, phenolic resins, etc.), or rubber materials (e.g. natural rubbers, styrene butadiene rubbers, etc.), TSH blowing agent is able to work well with them to realize foaming effect. Moreover, TSH blowing agent can be used in different production processes, such as injection molding, extrusion, molding, spraying, etc., to meet the production needs of different products. This wide range of applicability makes TSH blowing agent widely used in many industries, providing strong support for improving product performance and developing new materials.
Environmentally friendly properties
With the growing awareness of environmental protection, TSH blowing agent has certain advantages in terms of environmental protection. Compared with some traditional blowing agents, the gases produced during the decomposition of TSH blowing agents are mainly nitrogen and carbon dioxide, which are less harmful to the environment and do not cause problems such as ozone layer depletion. At the same time, TSH blowing agents are also formulated to pay more attention to environmental protection requirements and minimize the use of some hazardous substances. For example, some TSH blowing agents are formulated to avoid the use of potentially environmentally hazardous ingredients such as fluorinated compounds. In addition, products manufactured using TSH blowing agents are easier to recycle and reuse after disposal due to the special characteristics of the foam structure, which is conducive to resource recycling and environmental protection.
Conclusion
As a material with important applications in modern industry, the proper use of
TSH blowing agents is essential for improving product quality and performance. Whether in the field of plastic products, rubber products or construction materials, the proper use of TSH blowing agents can bring excellent properties such as light weight, heat insulation, sound insulation, etc., and at the same time satisfy the requirements of environmental protection and production efficiency.
