Application analysis of magnesium hydroxide in rubber hose and adhesive tape
Magnesium hydroxide, as a multifunctional inorganic material, has attracted much attention for its functions as a flame retardant, filler, and heat stabilizer. Especially in the production process of rubber hoses and tapes, the role of magnesium hydroxide is particularly prominent, which not only improves the performance of the product, but also enhances safety and environmental protection.
1、 Basic properties and classification of magnesium hydroxide
Magnesium hydroxide (Mg (OH) ₂) is a white powdery substance with excellent heat resistance and chemical stability. It belongs to a typical layered structure compound, which decomposes into magnesium oxide and releases water vapor at high temperatures. This endothermic reaction makes it an efficient and environmentally friendly flame retardant.
According to different production processes, magnesium hydroxide can be divided into light magnesium hydroxide and heavy magnesium hydroxide. The former is mostly used for filling modification of polymer materials, while the latter is suitable for product systems with higher density requirements. In the manufacturing of rubber hose adhesive tape, lightweight magnesium hydroxide with moderate particle size, high whiteness, and good dispersibility is usually selected.
2、 The main function of magnesium hydroxide in rubber hose adhesive tape
1. Excellent flame retardant performance
With the increasing awareness of fire safety in society, flame retardancy has become an important indicator that cannot be ignored in the design of rubber hose and tape products. Magnesium hydroxide can absorb a large amount of heat during combustion, while releasing water vapor to dilute combustible gases, effectively suppressing flame spread.
Compared to traditional halogen flame retardants, magnesium hydroxide does not contain toxic halogen elements and does not produce a large amount of black smoke and toxic gases during combustion, making it more environmentally friendly and in line with the development trend of modern flame retardant materials.
2. Good filling effect
When magnesium hydroxide is used as a filler, it can improve the mechanical properties of the rubber matrix. Moderate addition can not only reduce raw material costs, but also improve the hardness, wear resistance, and dimensional stability of the rubber material. This is particularly important for hoses and tapes that are subjected to dynamic stress environments for a long time.
In addition, magnesium hydroxide has a lower wear value and causes less wear on processing equipment, which helps to extend the service life of equipment and improve production efficiency.
3. Enhance thermal stability
Rubber materials are prone to aging and deterioration in high-temperature environments, which affects their service life. Magnesium hydroxide can delay the thermal degradation process of rubber materials and improve their thermal stability by absorbing heat and releasing water molecules. This is a crucial performance guarantee for industrial hoses and conveyors that need to work in high-temperature environments.
3、 Application performance of magnesium hydroxide in different rubber material systems
In actual production, there are various types of rubber used for rubber hoses and tapes, including natural rubber (NR), styrene butadiene rubber (SBR), chloroprene rubber (CR), ethylene propylene rubber (EPDM), etc. The application performance of magnesium hydroxide in such rubber systems also varies.
Natural rubber system: Magnesium hydroxide can effectively improve the aging resistance of natural rubber and enhance its tear strength.
Chloroprene rubber system: Due to the inherent flame retardancy of chloroprene rubber, the addition of magnesium hydroxide further enhances its comprehensive fire resistance performance.
Ethylene propylene rubber system: Magnesium hydroxide exhibits excellent electrical insulation properties in this type of material, making it particularly suitable for use in tape products such as cable sheaths that require electrical performance.
Therefore, in the specific formula design, the dosage and particle size of magnesium hydroxide should be adjusted reasonably according to the rubber type and product use to achieve the best synergistic effect.
4、 Process and precautions for adding magnesium hydroxide
Although magnesium hydroxide has many advantages, the following aspects still need to be noted in practical applications:
1. Particle size control
The particle size of magnesium hydroxide directly affects its dispersion effect in rubber matrix. Generally speaking, the finer the particle size, the better the dispersibility, and the more obvious the reinforcement effect. But too fine powder can also easily cause dust to fly, increasing the difficulty of operation. It is recommended to choose micro - or nano scale magnesium hydroxide products that have undergone surface treatment.
2. Surface modification treatment
There is a certain interface compatibility problem between untreated magnesium hydroxide and rubber matrix, which can easily lead to a decrease in mechanical properties. Therefore, it is usually necessary to perform surface activation treatment on it, such as using silane coupling agents, stearic acid or titanate ester modifiers, to enhance its binding force with rubber molecules.
3. Add proportional control
The amount of magnesium hydroxide added is generally controlled at 50-150 parts per hundred parts of rubber, and the specific amount should be optimized according to the flame retardant level, mechanical performance requirements, and processing conditions of the product. Excessive addition may affect the elasticity and flexibility of the adhesive material.
4. Coordination with other additives
Magnesium hydroxide is often used in combination with other flame retardant additives such as aluminum hydroxide, zinc borate, antimony oxide, etc. to achieve better flame retardant synergistic effects. At the same time, it is necessary to consider the interactions between the vulcanization system, plasticizers, anti-aging agents, and other components to ensure the balance of the overall formula.
With the increasingly strict environmental regulations of the country, the use of traditional halogenated flame retardants is gradually being restricted. Magnesium hydroxide is becoming a representative of the new generation of green flame retardant materials due to its non-toxic, low smoke, and environmentally friendly advantages. Especially in the fields of automobiles, construction, electricity, rail transit, etc., the demand for high-performance flame-retardant rubber hoses and tapes is constantly increasing, providing broad space for the application of magnesium hydroxide.