Do you know all that antioxidant stuff?
What is antioxidant
Antioxidants are substances that prevent and resist the oxidation of substances. There are a variety of antioxidants, from low molecular weight to high molecular weight, from natural to synthetic.
Classification of antioxidants
Typical main antioxidants include the following two categories:
Aromatic amine antioxidants: amine antioxidants are almost all derivatives of aromatic secondary amines, mainly diaryl secondary amines, p-phenylenediamine and ketamine, aldehyde amine and other classes. Most of them have good antioxidant efficacy, but easy to produce color stains, mainly used in the rubber industry and polyurethane products.
Hindered phenolic antioxidants: the most widely used class of main antioxidants. Antioxidant effectiveness is generally weaker than amine antioxidants, but no pollution, mainly used in plastics and light-colored rubber products. Many famous products such as 1010, 1076, all belong to this category.
Mainly thiodipropionate and other thioesters and phosphite two categories. They are mainly used in polyolefins, and phenolic antioxidants and used to produce synergistic effects.
Phosphite is the most widely used auxiliary antioxidant, typical products such as 168.
Sulfide is another type of auxiliary antioxidant, typical products such as DLTDP and DSTDP.
Polymer and heavy metal contact, the catalytic effect of heavy metal ions will cause the polymer degradation reaction, such as the core wire of the cable material is copper, often caused by copper damage, and thus the need to add copper passivation, metal passivation can significantly improve the stability of the polymer.
Common antioxidant grades
Polyolefin: PP Film, PP Molding, HEPE Pipe, PP/HDPE Tape/ PE Wire&Cable, PE Molding, LDPE/EVA Film, LLDPE Film
Polyurethane: RIM, TPU
Engineering plastics: POM, PA, PBT/PET
Polyolefin: PP, PE, LDPE, EVA, LLDPE
Styrene: ABS, PC/ABS, IPS, GPPS
Elastomer: S-SBR, BR, EPDM, SBS/SRS, TPE
Polyvinyl chloride: PVC
Polyurethane: RIM, TPU
Engineering plastics: PC, PMMA
The main producers of antioxidants
Domestic antioxidants and imported antioxidants in the end there is no difference
According to the well-known petrochemical enterprises on the hindered phenol antioxidant 1010 and phosphite antioxidant 168, using three kinds of domestic products and one kind of imported products to carry out a detailed comparative study. The study was conducted in accordance with industry standards, the appearance of the products, melting point range, volatile matter, ash, solution clarity, solution transmittance, main content and active components were tested. The study also tested the organotin content of the antioxidant 1010. 1010 with high organotin content will be limited in application. In addition, the testing of antioxidant 168 in this study extended the hydrolysis test by testing until all products were hydrolyzed.
The results showed:
1, three kinds of domestic antioxidant 1010 are in full compliance with the industry standard indicators, performance and imported products are similar, in general production can be equivalent to use.
2, one of the domestic antioxidant 1010 using a tin catalyst, but in some special applications, if the antioxidant is required to use tin-free process, it is necessary to pay attention to the selection of the appropriate manufacturers.
3, three kinds of domestic antioxidant 168 hydrolysis resistance are in line with or exceed the industry standard, against the imported antioxidant 168 hydrolysis resistance is the best.
Commonly used plastics how to choose antioxidants, light stabilizers
About antioxidants and light stabilizers
1. About antioxidants and light stabilizers
Antioxidant – antioxidant refers to the polymer oxidation and aging phenomenon can play a role in delaying a class of chemical substances. When it exists only in small amounts in the polymer system, it can slow down or inhibit the oxidation process of the polymer, thus preventing the aging of the polymer and prolonging its service life, also known as “antioxidant”.
Light stabilizers – due to long-term exposure of polymer materials to sunlight or placed under strong fluorescent light, absorbing ultraviolet energy, causing automatic oxidation reaction, resulting in polymer degradation, making products discolored, brittle, performance degradation, so that can not be used. Any measure that can inhibit or slow down this process is called light stabilization technology, and the substances added are called light stabilizers.
Detailed explanation of BASF antioxidants and light stabilizers
2. Selection of antioxidants, light stabilizers reference principles
Selection of antioxidants, light stabilizers, should be based on the type and model of plastic materials, processing equipment and process conditions, other chemical additives and the amount of varieties added to the product’s use of the environment and the period of time and other factors to determine the antioxidant, light stabilizers and other varieties. Selection of industrial use of antioxidants, light stabilizers should be based on the following principles.
5）Environmental and hygienic
Recommended reading: Selection of antioxidants and light stabilizers, these principles do you understand? (Attachment: antioxidant supplier list)
How to choose antioxidants and light stabilizers?
The following table lists the commonly used plastic resins and commonly used antioxidants, light stabilizers corresponding to the selection of relations, this relationship is only for the design of the formula to provide a starting point, the specific antioxidant, light stabilizer varieties need to be determined by the test results.
The same main series of resins are divided into a number of branch series due to different polymerization processes, molecular structure, etc., such as polyethylene PE series of high-density polyethylene HDPE, low-density polyethylene LDPE, linear low-density polyethylene LLDPE, polyvinyl chloride PVC series of hard polyvinyl chloride U-PVC, soft polyvinyl chloride P PVC, soft polyvinyl chloride P-PVC, impact resistant polyvinyl chloride I-PVC and so on. In the same main series of resins, there are differences in the resistance to thermal oxidation and photo-oxidation of different branch series of resins, which must be understood when designing plastic formulas.