What are the characteristics of PTFE plates lining chemical reaction vessels
Information summary:The core advantage of PTFE lining in chemical reaction vessels lies in its inherent chemical inertness and extreme environmental resistance, combined with the protective effect of the lining structure on the reactor substrate. Its characteristics can be developed from four dimensions: chemical stability, temperature resistance, physical properties, and process adaptability, as follows:
The core advantage of PTFE lining in chemical reaction vessels lies in its inherent chemical inertness and extreme environmental resistance, combined with the protective effect of the lining structure on the reactor substrate. Its characteristics can be developed from four dimensions: chemical stability, temperature resistance, physical properties, and process adaptability, as follows:
1、 Good chemical stability: suitable for multi-media reactions
PTFE is known as the "plastic king", and its chemical inertness is the core value of lining applications, specifically manifested as:
Resistant to the corrosion of the vast majority of chemical media: it has no reaction to strong acids (such as concentrated hydrochloric acid, sulfuric acid, nitric acid), strong bases (such as sodium hydroxide, potassium hydroxide), strong oxidants (such as potassium permanganate, hydrogen peroxide), organic solvents (such as ethanol, acetone, toluene), and even "aqua regia" (a mixture of concentrated hydrochloric acid and concentrated nitric acid). It is only slightly corroded by molten alkali metals (such as sodium, potassium) or fluorine elements at high temperatures.
No dissolution/contamination: PTFE has a stable molecular structure (high carbon fluorine bond energy), and will not undergo molecular chain breakage or dissolve any substances into the reaction system within the temperature range of chemical reactions (usually ≤ 200 ℃). It is particularly suitable for high-purity chemical synthesis (such as pharmaceutical intermediates, electronic grade reagents) or food grade material reactions, avoiding contamination of the inner lining material products.
2、 Wide range temperature resistance: suitable for extreme reaction conditions of high and low temperatures
The temperature resistance range of PTFE is much better than most engineering plastics, and it can meet the needs of "high and low temperature alternation" or "continuous extreme temperature" in chemical reaction vessels:
High temperature resistance: Long term use temperature can reach -200 ℃~260 ℃ , short-term (within a few hours) can withstand high temperature of 300 ℃, fully covering common reaction temperatures in the chemical industry (such as esterification reaction 80-150 ℃, polymerization reaction 100-220 ℃), and there will be no softening, deformation or decomposition at high temperature (decomposition temperature needs to exceed 400 ℃, and the decomposition products are non-toxic and risky).
Low temperature resistance: It can maintain good flexibility and mechanical strength in an ultra-low temperature environment of -200 ℃, and will not become brittle due to low temperature. It is suitable for reactions that require low-temperature freezing (such as low-temperature crystallization reactions in some organic synthesis), and avoids cracking of the lining due to sudden temperature changes.
3、 Excellent physical performance: balancing durability and reaction efficiency
The PTFE lining not only resists corrosion, but its physical properties also enhance the user experience and lifespan of the reaction vessel
Lower friction coefficient: The surface friction coefficient of PTFE (about 0.04, only higher than polyimide) is one of the lower known solid materials. Reactive materials (especially high viscosity materials such as resins and slurries) are not easy to adhere to the inner lining surface, reducing material residue (reducing cleaning difficulty and saving time), and avoiding secondary reactions of residual materials that affect product purity.
Good non stick: Similar to a "non stick pot coating", the material hardly adheres to the inner lining during the reaction process, making it suitable for intermittent reactions that require frequent discharge and cleaning (such as batch synthesis in pharmaceutical and chemical industries), while reducing the wear of tools such as scrapers on the inside of the pot.
A certain degree of mechanical toughness: Although PTFE plates have low hardness at room temperature (Shore D 50-60), they have excellent impact toughness and fatigue resistance, and can withstand slight impacts during the stirring process of the reaction vessel (such as accidental contact between the stirring blade and the lining). They are also not prone to cracking or detachment after long-term use (requiring excellent lining bonding processes such as hot pressing and welding).
4、 Strong process adaptability: compatible with various reactor structures and operations
PTFE lining can be adapted to various reaction vessels through different processing techniques to meet diverse production needs
Flexible molding process: Customized cutting and hot pressing can be carried out according to the shape of the reaction vessel (round, square, irregular), or welded together to form a whole inner lining. Even the stirring shaft, flange and other components of the reaction vessel can be fully covered to avoid substrate exposure (prevent local corrosion).
Suitable for multiple heating/cooling methods: PTFE has a low thermal conductivity (about 0.24 W/(m · K)), but through "thin lining design" (usually 3-5mm thickness) or "composite with metal substrate" (such as PTFE steel composite plate), it can balance corrosion resistance and thermal conductivity efficiency, without affecting temperature control methods such as jacket heating and coil cooling of the reaction kettle.
Easy to maintain and repair: If there are scratches or minor damages on the inner lining, it can be repaired with a dedicated PTFE repair agent (without the need for overall replacement); If it needs to be replaced after long-term use, the PTFE plate can be softened by heating and peeled off, without damaging the reactor substrate (such as stainless steel, carbon steel), reducing equipment maintenance costs.