Antioxidants – Stabilizers

Antioxidants / Stabilizers

Like everything else, Rubber is subject to degradation, which becomes particularly rapid if it are exposed to oxygen, heat and light.

What is degradation and why does it happen?

Degradation is a generic term used to describe any change in the rubber properties when compared to the initial desirable properties.

Most synthetic rubbers are produced using controlled chain reactions to achieve molecules of desired properties. However, once the initial product is exposed to various physiological factors, chemical reactions start within the product and change its chemical and physical properties. The almost inevitable oxidation process starts a chain reaction, which speeds up the degradation unless a stabilizer is used.

Process Stabilizers

After polymerization most synthetic rubbers are shipped to manufacturers of the final rubber article. During processing, the rubber undergoes a series of heating cycles. Each such cycle causes degradation, a result of the combined action of heat and oxygen. Process stabilizers are used to prevent such degradation during processing.

CRISTOL-TNPP* – Hydrolysis Resistant
TRI NONYL PHENYL PHOSPHITE (CAS NO 26523-78-4)

CRISTOL-TNPP (HR) is used to enhance the heat, colour and processing stability of a broad spectrum of polymers including:

Styrene Butadiene Rubber (SBR)
Acrylonitrile – Butadiene Rubber (NBR)
Poly Butadiene Rubber (PBR)
Styrene Butadiene Rubber Latex
Radiation Vulcanized Natural Rubber Latex (RVNRL)

TNPP is often used in a water emulsion for stabilizing polymers. It is critical that TNPP used in this application has good hydrolytic stability, since hydrolyzed TNPP is not an effective stabilizer and also can cause black specks. It is effective even in low concentrations.

CRISTOL-TNPP (HR) is the only recommended antioxidant for Radiation Vulcanized Nitrile Rubber Latex (RVNRL) for improved transparency.

CRISTOL-SP
Styrenated Phenol (CAS No: 61788-44-1)

CRISTOL-SP is a stabilizer for synthetic elastomers as well as a medium activity non-staining, non-discoloring antioxidant for latex and solid rubber formulations.

It is a general-purpose antioxidant providing oxidation resistance and moderate heat aging resistance properties to NR, and to SBR, NBR, IR, BR and CR.

It has excellent colour stability and is widely used in white and light coloured applications such as flooring, sporting goods, shoe soles, general mechanical goods, latex and carpet backing.

It may reduce surface “crazing” caused by UV light degradation.

It may be used alone or in combination with other antioxidants for the stabilization of synthetic elastomers.

Styrenated Phenol is regulated for use in articles coming in contact with food as specified under FDA 21 CFR 177 2600, 175 105 and under-BgVV XXI, Categories 1-4.