Antioxidants
Virtually all polymeric materials undergo oxidation reactions. Oxidation can occur at every stage of the life cycle of a polymer, i.e. during manufacturing and storage of the material or during processing and end-use.
Typical manifestations of oxidation of polymers can be change of viscosity during processing, appearance, and loss of mechanical properties such as elongation, impact strength, tensile strength, and flexibility. Antioxidants protect polymers against oxidation by controlling molecular weight changes that lead to a loss of physical, mechanical, and optical properties.
Among other factors heat, light and mechanical stress can result in the degradation of the polymer.
Antioxidants interrupt the degradation processes in different ways, depending on their structure. The two major classifications are: chain terminating primary antioxidants and hydroperoxide decomposing secondary antioxidants.
Primary antioxidants react rapidly with free radicals and are, therefore, called "Radical Scavengers". The majority of primary antioxidants for polymers are sterically hindered phenols.
Primary antioxidants:
Secondary antioxidants, including phosphites and thioesters, react with hydroperoxides to yield non-radical products. They are particularly useful in synergistic combinations with primary antioxidants.
Phosphites are most effective during processing and protect both the polymer and the primary antioxidant.
Thioesters are useful in increasing the long-term thermal stability in conjunction with phenolic antioxidants. Irgafos® 168, Irgafos® 126, Irganox® PS 800 and Irganox® PS 802 are secondary antioxidants.
In multifunctional stabilizers, several functions are combined in the same molecule: the most widely used combination are sterically hindered phenols with sulfur substituents or sterically hindered phenols with copper chelating function (metal deactivators). Irganox® 1035, Irganox® 565, Irganox® 1520 L, Irganox® MD 1024 are examples of multifunctional additives.
A third class of antioxidants are the radical scavengers. Scavenging the radicals immediately stops the degradation. They are mainly used for extrusion processing. Irganox® E 201 and the blend Irgastab® FS 301 belong to this class of antioxidants.
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Disposable and durable packaging carry a variety of requirements, ranging from ease of processing, economical efficiency to food contact compliance and stunning aesthetics.
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1Processing and ThermalLink Description (Optional)
Benefit | Processing & thermal stabilizers | Light stabilizers | Clarifiers |
Bottles PO | Irganox® B 215, B 225, B 561, 1010 Irgafos® 168 |
Tinuvin® 326 | Irgaclear® XT 386 |
Bottles PET | Irganox® B 561 Irgafos® 126, 168 |
Tinuvin® 234 |
Benefit | Processing & thermal stabilizers | Light stabilizers | Nucleators & antistatic agent |
Caps | Irganox® B 215, B 561, 1010 Irgafos® 168 |
Tinuvin® 326 Chimassorb® 2020 |
Irgastab® NA 287 Irgaclear® XT 386 |
Benefit | Processing & thermal stabilizers | Light stabilizers | Nucleators & antistatic agent |
PP and PE | Irganox® B 215, B 900, 1010, 1076, E 201 Irgafos® 168 Irgastab® 301 Irgastab® XT 500 |
Chimassorb® 2020 Tinuvin® 326 |
Irgaclear® XT 386 Irgastab® NA 287
Irgastat® P |
Benefit | Processing & thermal stabilizers | Light stabilizers | Nucleators & antistatic agent |
PP and HDPE | Irganox® B 215, B 225, B 561, 1010 Irgafos® 168 |
Chimassorb® 2020 Tinuvin® 326 Uvinul® 4050 (PP-food) Tinuvin® 783 |
Irgastab® NA 287
Irgastat® P |
Benefit | Processing & thermal stabilizers | Light stabilizers | Antistatic agent |
FIBC - PP | Irganox® B 215 Irganox® B 225 |
Tinuvin® 791 Tinuvin® 783 Tinuvin® XT 55 Chimassorb® 2020 Uvinul® 4050 |
Irgastat® P |
IBC - HDPE | Irganox® B 561 Irganox® B 215 |
Tinuvin® 783 Chimassorb® 2020 Tinuvin® 326 |
Irgastat® P |
FFS - (L)LDPE | Irganox® B 215 Irganox® B 900 |
Tinuvin® 783 Chimassorb® 2020 Tinuvin® 326 |
Irgastat® P |