Promotion of FTO wax separation and refining technology (long-term effective)

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This post was last edited by liaifeng on 2018-8-18 at 10:15. Fertile synthesis wax separation and refining technology 1: Overview of refined products from fertile synthesis wax. The main foreign manufacturers of such wax are SASOL in South Africa and Shell in the Netherlands. In recent years, China has also intensified its research on FTO synthesis technology. By relying on coal-based oil FTO synthesis technology with independent intellectual property rights, a range of coal-based oil products have been successfully developed, thereby completely changing the situation in which foreign brands dominated the market for FTO synthesis waxes. Crude wax, one of the coal-based synthetic oil product lines, serves as a raw material for refined FTO wax products. Through advanced extraction and distillation techniques, crude FTO wax can be further processed to produce a range of FTO synthesized waxes. Fischer-Tropsch synthesis waxes are generally named according to their drip melting point, with the main product grades being 60, 70, 95, 100, 105, 110, and 115. 2 Structure and Properties of Fischer-Tropsch Synthesis Wax: Fischer-Tropsch wax is primarily composed of straight-chain, saturated high-carbon alkanes with a relative molecular mass ranging from 500 to 1,000. This composition endows the chemical with a fine crystalline structure, a high melting point, a narrow melting range, low oil content, low penetration value, low mobility, low melt viscosity, as well as hardness, wear resistance, and high stability. Compared to conventional polyethylene waxes (PE waxes), the significant difference between FTO synthesis waxes and them lies in (a) molecular weight. Fischer-Tropsch wax has a much lower molecular weight than PE wax, fewer side chains, and a higher degree of crystallinity; it can easily penetrate into high-viscosity macromolecular chains, significantly reducing the viscosity of the melt. It exhibits low migratory behavior during processing, and provides excellent lubrication effects over time. (b) Fischer-Tropsch wax consists of saturated straight-chain alkanes without double bonds; it has strong antioxidant properties and the products exhibit good weather resistance. (c) The viscosity of FTO wax is much lower than that of PE wax. It’s only about 10. A smaller amount is sufficient to achieve the same lubricating effect. The usage amount is only 70-80% of that of PE wax. Refer to Table 1: FTO wax has good compatibility with PVC and is suitable as both an internal and external lubricant. It can serve as an effective internal lubricant to control shear conditions, promote flow, regulate friction and melting properties, thereby improving thermal stability. At the same time, due to its high crystallinity and highly linear structure, FTO wax enables PVC products to achieve optimal physical and processing properties. As needed, the FTO process can synthesize alkanes with different chain lengths to adjust the molecular weight of the final product, thereby producing a series of products. Properties of Fischer-Tropsch wax and PE wax: Parameter name, Fischer-Tropsch wax, PE wax; Molecular weight, 800–1000, 2000–5000; Appearance, powdery, beaded, granular, powdery, beaded, flaky; Color, white, white; Melting range, narrow, wide; Melt viscosity (140°C), cps, 6–10, 20–60; Penetration at 0.1 mm at 25°C, low, high, 3.0. Comparison of production and application technologies for Fischer-Tropsch wax: 3.1 Lubricants for PVC product processing. Various additives used in PVC, such as heat stabilizers, lubricants, impact modifiers, processing aids, and pigments, are formulated based on the requirements of product performance. The goal is to minimize the cost of the formulation while ensuring product quality and meeting the requirements of the processing process. Lubricants are one of the very important factors affecting the processing of rigid PVC products; they primarily serve to improve the flowability of the PVC resin during processing and the ease of demolding of the finished products, while preventing defects in the products due to adhesion inside the machine or mold. Due to the polar molecular structure of PVC resin, the forces acting between its molecular chains are strong; as a result, it tends to decompose under the influence of heat, light, oxygen, and high shear forces during processing. Therefore, lubricants need to be added during the processing of PVC resin. Internal lubricants help reduce the forces between PVC molecules, thereby minimizing the generation of internal friction heat and facilitating plasticization. The addition of external lubricants reduces the friction and adhesion between PVC and steel, controls the plasticization rate, and improves the flowability of PVC, making it easier to melt and shape. Generally speaking, internal lubricants promote plasticization, while external lubricants delay it. The plasticization degree of PVC-U is around 65%, at which point it exhibits the best mechanical properties. Therefore, it is necessary to strike a proper balance among the fluidity, anti-sticking property, and plasticization rate of PVC resin, that is, to achieve a balance between internal and external lubrication, in order to enable economical and continuous production. 3.1.1 Mechanism of lubrication equilibrium for Fischer-Tropsch synthesis wax. The main characteristic of external lubricants is interfacial lubrication. During processing, external lubricants readily migrate to the product surface or to the interface between the melt and the processing machinery. There, they become oriented molecularly and form a layer of lubricant molecules through physical adsorption. Internal lubricants can dissolve between the polymer molecular chains, reducing internal friction, lowering the viscosity of the melt, increasing the melting rate of plastics, and improving their plasticization properties. Fischer-Tropsch synthesized wax is primarily used as an external lubricant in PVC processing. Due to its low molecular weight, low melting viscosity, high melting point, and narrow melting range, a small amount of this wax is sufficient to achieve the same lubricating effect, thereby reducing the negative impact of lubricants on the physical and mechanical properties of the product. It offers advantages over PE wax in terms of balancing internal and external lubrication. 3.1.2 Fert synthesis wax to improve the processing properties of PVC products. PVC resin has characteristics such as poor fluidity, low thermal stability, and tendency to decompose; the products manufactured from it are brittle and have poor impact resistance. Therefore, various auxiliary materials need to be added during the processing stage to enhance the properties of these products. In the processing of PVC resin, the choice of lubricant is crucial. The ability to achieve the same lubricating effect with a small amount of lubricant is an important requirement, and Fertose synthesis wax meets this requirement perfectly. This reduces the difficulty of formula design and effectively improves the efficiency of using impact modifiers and processing aids. Fischer-Tropsch synthesized wax exhibits a significant synergistic effect with stabilizers used in PVC processing; it can effectively extend the thermal stability period and increase the range within which process temperatures can be adjusted. This effect is particularly notable with high-melting-point Fischer-Tropsch synthesized wax in the processing of CPVC resin. The narrow range of adjustable parameters in CPVC resin processing makes it more difficult to manufacture products, and the use of high-melting-point Fischer-Tropsch synthesized wax can improve the lubrication during the later stages of CPVC product processing, thereby enhancing the product’s appearance and mechanical properties. Fischer-Tropsch synthesis wax can effectively reduce the precipitation of small-molecule impurities during the product processing process. When it comes to the precipitation of small molecular impurities, many people think it is caused by an excessive amount of lubricant used, but this is not necessarily the case. Excessive lubricant will definitely migrate to the surface of the product, especially in the production of PVC pipes; impurities will adhere to the die and accumulate, causing scorching and resulting in a loss of luster on the product surface. The precipitation of impurities on the surface of PVC during processing is mainly due to the precipitation of small-molecule substances present in the stabilizers used, especially calcium-zinc stabilizers. Impurity precipitation occurs after a period of production, and in some cases it is quite severe; these precipitated impurities can even adhere to the sizing sleeves. By adding an appropriate F-T synthesis wax to the formula to maintain a balance between internal and external lubrication, the surface precipitation of impurities can be effectively reduced. 3.1.3 Solutions to common problems associated with FTO synthesis waxes in the processing of PVC products, including analysis of the reasons behind process-related issues and corresponding solutions; poor surface finish is attributed to the use of lubricants – insufficient amounts of lubricant, poor thermal stability of the lubricants, high losses in the early stages, and inadequate lubrication later on. Using high-melting-point FTO synthesis wax can effectively solve the problem of insufficient lubrication in later stages. The product appears to have black lines, indicating an imbalance in internal and external lubrication; insufficient amount of external lubricant is used, or the quality of the lubricant is poor. Using FTO wax can effectively solve the problem of insufficient external lubrication. The stabilizer and lubricant system used to control impurities in the die for PVC pipe production is not properly configured. Calcium-zinc stabilizers show significant performance. Optimally combine the stabilizer and lubrication systems, appropriately reduce additives such as polyols, and increase the amount of Fischer-Tropsch synthesized wax used. The impurities in the sizing sleeves used in PVC pipe production are mainly due to an unreasonable formulation of calcium-zinc stabilizers; these stabilizers tend to migrate to the surface of the product and, upon rapid cooling, adhere to the surface of the sizing sleeve. Reduce the use of low-melting-point lubricants and increase the use of high-melting-point lubricants. Products that fail the dichloromethane test have defective outer surfaces, mainly due to low die temperature ； The inner surface of the product is unacceptable; mainly due to excessive lubrication and poor plasticization. The key issue is the poor quality of the lubricant used, which affects the quality of product plasticization. Using FTO-synthesized wax can effectively solve the problem of failed dichloromethane tests. A smaller amount is sufficient to achieve the same lubricating effect, making it easier to optimize the production formula. There are various reasons for inadequate hydraulic performance, with the lubricant being the key issue. Fischer-Tropsch synthesized wax requires a smaller amount to achieve the same lubricating effect, with little impact on the mechanical properties of the product. This makes it easy to reasonably configure the production formula, with a wide range of adjustability for the production process. 3.2 The effective improvement of the lubrication system using FTO synthesis wax with calcium-zinc composite stabilizers: Depending on the type of auxiliary stabilizer, the calcium-zinc composite stabilizers available on the market can be divided into: (a) calcium-zinc-hydrotalcite/modified hydrotalcite composite stabilizers. (b) Calcium-zinc-polyol composite stabilizer. (c) Calcium-zinc-rare earth composite stabilizer. (d) Multi-component formulations combining metal soaps such as calcium and zinc soaps with various types of auxiliary stabilizers like hydrotalcites, polyols, and β-diketones. For different stabilizer systems, various chemical components such as antioxidants and internal/external lubricants must be added to ultimately produce calcium-zinc stabilizers with distinct formulations. Calcium-zinc composite stabilizers in any system rely on a good lubrication system, as such a system features low volatility, excellent demolding and flow properties, and it can enhance the high-temperature stability of the stabilizer, prolong its thermal stability time, reduce the precipitation of impurities, and improve the weather resistance of the product. The calcium-zinc composite stabilizer lubrication system is widely used by most companies due to cost considerations; however, this system has drawbacks such as the precipitation of small molecules during the processing stage and a decline in lubrication performance over time. Some companies have also tried to use imported FTO synthetic wax lubrication systems to improve the performance of calcium-zinc stabilizers, with noticeable results; however, the high costs make the product prices unaffordable. Fischer-Tropsch synthesized wax exhibits a significant synergistic effect with calcium-zinc stabilizers and other additives; it helps the stabilizers to extend the thermal stability period, reduce the viscosity of the melt, and decrease the friction between molecules as well as between molecules and the mechanical walls. Improve the initial coloring of the product. It has a positive impact on the mechanical properties of the product. It is precisely these notable characteristics of FTO-synthesized waxes that enable their widespread use in the production of calcium-zinc stabilizers, as the structure and properties of such waxes particularly meet the technical requirements for lubricants in stabilizer manufacturing. The domestically produced Fischer-Tropsch wax was introduced in 2015, providing a technical guarantee for improving the quality of domestic stabilizers. Given that calcium-zinc stabilizers are green, environmentally friendly, and highly compatible with **strategies for environmental protection, they will undoubtedly accelerate the development of calcium-zinc stabilizers in the foreseeable future, as they play a key role in FTO synthesis waxes. 3.3 Hot melt wax is the most effective regulator of hot melt adhesive properties. The melting point and crystallinity of the wax added to the hot melt adhesive determine its initial setting temperature and curing time; they also affect the plasticity and tensile properties of the hot melt adhesive. Fischer-Tropsch wax with low viscosity properties can reduce the viscosity of polymers and resins, facilitating their efficient mixing as well as the pumping of hot melts. Common synthetic waxes used in hot melt adhesives include PE wax and Fischer-Tropsch wax. Fischer-Tropsch synthesized wax has a saturated straight-chain alkane molecular structure, featuring high melting points and high hardness. Compared to PE wax, it has a narrow melting range and good weather resistance; therefore, it is widely used in hot melt adhesives that require good weather resistance and rapid solidification at high temperatures. 3.4 Application of Fertowax in the processing of masterbatches In the production of masterbatches, it is first necessary to disperse the pigment aggregates into primary particles or crystals under shear force, thereby achieving a more uniform initial state. However, after the pigment aggregates are dispersed, they tend to re-aggregate due to gravitational forces. Fertosynthesis wax can effectively wet and penetrate into the pores of these aggregated particles, covering the surface of the pigments; under shear force, it helps to disperse the pigment aggregates better and thus prevents re-aggregation. Based on the principles of masterbatch processing, although Fertowax provides good wetting, penetration, and coating effects, its low viscosity reduces the shear force on the agglomerates, resulting in poor pigment dispersion. Conversely, due to its high molecular weight and branched structure, polyethylene wax has a relatively high viscosity, making it more suitable for masterbatch processing. 3.5 Inks and Coatings: The micro-powder waxes formed by spraying, with their well-shaped spherical particles and low surface tension, can be used in various inks and water-based/oil-based coatings, providing good lubrication effects while also enhancing the scratch resistance and wear resistance of the coatings. Furthermore, FTO wax can also be used in cosmetics, brighteners, and other products. 3.6 Commonly Used Domestic FTO Synthesized Waxes http://www.hdfree.cn/ueditor/php/upload/image/20170729/1501300950370206.png Note: W denotes iron-based catalysts ； WG denotes cobalt-based catalysts. 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