Heat stabilizer is one of the important categories in the detection of PVC (polyvinyl chloride) plastic processing aids. It is synchronized with the birth and development of PVC resin and is mainly used in PVC resin processing. Since PVC is reheated (processing), it is easy to decompose HCL, causing product deterioration and discoloration, which affects processability and product appearance. Therefore, heat stabilizers must be added in the production of PVC to inhibit and absorb HCL, prevent HCL damage and catalyze PVC Continue to decompose. The purchase of heat stabilizers has become an important part of the quality control of PVC plastic products. Today, we will analyze the performance of the following eight heat stabilizers in detail for your reference when purchasing.
1. Detection and analysis of lead salt heat stabilizers
Lead salt is the most commonly used heat stabilizer for PVC, and it is also a very effective heat stabilizer. Its dosage can account for more than 70% of PVC heat stabilizer. The advantages of lead salt stabilizers: excellent thermal stability, long-term thermal stability, excellent electrical insulation performance, good weather resistance, and low price. Disadvantages of lead salt stabilizers: poor dispersibility, high toxicity, initial coloring, it is difficult to obtain transparent products, and it is difficult to obtain products with bright colors, lack of lubricity, and easy to produce sulfur pollution.
2. Detection and analysis of metal soap heat stabilizers
It is the second major main stabilizer whose dosage is second only to lead salt. Although its thermal stability is not as good as that of lead salt, it has lubricity. Metal soaps can be fatty acid (lauric acid, stearic acid, naphthenic acid, etc.) metal (lead, barium, cadmium, zinc, calcium, etc.) salts, among which stearates are the most commonly used. Metal soaps are generally not used alone, but are often used in combination with metal soaps or with lead salts and organic tins. It is non-toxic except Gd and Pb, and transparent except Pb and Ca, without vulcanization pollution, so it is widely used in soft PVC, such as non-toxic and transparent products.
3. Detection and analysis of organotin heat stabilizers
Organotin is the most effective heat stabilizer and the most widely used in transparent and non-toxic products. Its outstanding advantages are: good thermal stability, good transparency, and most of them are non-toxic. The disadvantage is high price and no lubricity. Most organotins are liquid, and only a few are solid. It can be used alone or in combination with metal soaps.
4. Detection and analysis of organic antimony heat stabilizer
It has excellent initial hue and hue retention, especially when the dosage is low, the thermal stability is better than that of organotins, and it is especially suitable for PVC formulations with twin-screw extruders. Organic antimony mainly includes antimony thiolate, antimony thioglycolate, antimony mercapto carboxylate, antimony carboxylate, and Thiopropionic acid, etc.
5. Detection and analysis of rare earth stabilizers
The materials selected are mostly rare earth oxides and rare earth chlorides, and most of the oxides and chlorides are single or mixed light rare earth elements such as lanthanum, cerium, praseodymium, and neodymium. The excellent mechanical properties of rare earth elements and their grouping principles are related to the geometric properties of rare earth elements. Because the radii of atoms and ions are important factors that determine the physical properties of the crystal, such as the configuration, hardness, density, and melting point, under normal temperature and pressure conditions, the rare earth metals lanthanum, praseodymium, and neodymium have a double hexagonal crystal structure, while cerium is cubic Crystal dense (face-centered) structure. When temperature and pressure change, most rare earth metals undergo crystal transformation.
6. Detection and analysis of hydrotalcite thermal stabilizer
Hydrotalcite is an anionic layered compound, also known as layered double hydroxide. The stabilizer is a new type of inorganic heat stabilizer developed by Japan in the 1980s. The typical chemical composition of hydrotalcite is Mg6A12(OH)l6 CO 3·4H20, and its structure is similar to that of brucite Mg(OH)2(Brucite). MgO6 octahedrons share the ridges to form a unit layer. The Mg part of the layer is Al Isomorphous substitution, so that the unit laminates composed of Mg2+, A13+, OH are positively charged, so there is an exchangeable anion COt between the layers to balance the charge and make the crystal as a whole point neutral; there are also between the laminates A certain number of water molecules.
7. Detection and analysis of composite lead salt stabilizer
Lead salt stabilizers are inexpensive and have good thermal stability. They have been widely used. However, the powder of lead salt is small, and the dust in the ingredients and mixing can cause lead poisoning. For this reason, scientists have developed a new type The composite lead salt heat stabilizer. This composite additive uses symbiotic reaction technology to mix the tri-salt, di-salt and metal soap in the reaction system with nascent grain size and various lubricants to ensure the full dispersion of the heat stabilizer in the PVC system At the same time, because it melts with the lubricant to form a granular shape, it also avoids the poisoning caused by lead dust. The composite lead salt stabilizer contains the heat stabilizer components and lubricant components required for processing, and is called a full package heat stabilizer.
8. Detection and analysis of auxiliary heat stabilizer
The auxiliary pad stabilizer itself does not have a thermal stabilizing effect, and only when used together with the main stabilizer can it produce a thermal stabilizing effect and promote the stabilizing effect of the main stabilizer. Auxiliary heat stabilizers generally do not contain metals, so they are also called non-metallic heat stabilizers. The main types of auxiliary heat stabilizer detection include: phosphite heat stabilizer, epoxy compound heat stabilizer, and polyol heat stabilizer.
Through the above treatment of lead salt heat stabilizer, metal soap heat stabilizer, organic tin heat stabilizer, organic antimony heat stabilizer, rare earth stabilizer, hydrotalcite heat stabilizer, composite lead salt stabilizer, auxiliary heat stabilizer By analyzing the detection performance of these eight major heat stabilizers, we can have a general understanding of heat stabilizers, which greatly helps us to select products suitable for ourselves according to our needs when purchasing heat stabilizers.