Color and melt-flow protection
Keeps yellowness index and MFR stable through extrusion, molding and regrind, where most processing damage happens.
Antioxidant 168 Supplier for Polymer Processing
SUNNOX® 168 is a hydrolysis-resistant phosphite secondary antioxidant. Blended with a phenolic primary such as 1010 or 1076, it protects color and melt flow while polyolefins and engineering plastics are extruded and molded.
CAS 31570-04-4 · Phosphite · Secondary antioxidant
Product Overview
Antioxidant 168 decomposes the hydroperoxides that form when polymer melts are sheared and heated, so it stops the chain reaction that causes yellowing, gels and melt-flow drift during processing. It is rarely used alone: the standard approach is a blend with a phenolic primary antioxidant, which carries the long-term protection in service. 168:1010 at 1:1 or 2:1 is the most common starting blend in PP and PE.
Typical specification. Every shipment is supplied with a batch COA; the limits that apply to your order are confirmed in the quotation and contract.
Key Benefits
Works with your phenolic
Synergistic with 1010 and 1076. Adding 168 often lets you hold or reduce the phenolic level for the same processing stability.
Hydrolysis resistant
More tolerant of humid storage and long sea transit than many other phosphites, so the powder stays free-flowing and active.
Technical Specifications
Typical specification. Every shipment is supplied with a batch COA; the limits that apply to your order are confirmed in the quotation and contract.
| Parameter | Typical value |
|---|---|
| Product Name | Antioxidant 168 |
| Brand | SUNNOX® 168 |
| CAS No. | 31570-04-4 |
| Chemical Name | Tris(2,4-di-tert-butylphenyl) phosphite |
| Molecular Formula | C42H63O3P |
| Molecular Weight | 646.9 |
| Appearance | White crystalline powder |
| Assay | ≥99.0% |
| Melting Point | 183–187 °C |
| Volatile Matter | ≤0.5% (105 °C, 2 h) |
| Light Transmittance — 425 nm | ≥98% |
| Light Transmittance — 500 nm | ≥98% |
Applications by Polymer
Pick a material family to see how 168 is normally used and what to confirm before your trial.
Polyolefins — PE & PP
The largest use of 168. Typical packages: 168:1010 1:1 or 2:1 for PP injection and fiber, 168:1076 for film. Total package levels of about 0.1–0.3% in PP and 0.05–0.15% in PE film are common starting points.
What to confirm for your application
- Resin grade, catalyst type and MFR target
- Number of extrusion passes and regrind share
- Current antioxidant package and dosage
Polyamide — PA
Used with a phenolic primary to limit discoloration during compounding of PA6 and PA66, including glass-filled grades.
What to confirm for your application
- PA type and filler content
- Processing temperature and residence time
- Color target (YI or ΔE) after molding
Polycarbonate — PC
Helps protect clarity and color at the high melt temperatures PC needs. Usually dosed low, alongside the base resin stabilizer.
What to confirm for your application
- PC grade and whether it is a blend (PC/ABS)
- Melt temperature and optical requirements
- Existing stabilizer system
ABS & Styrenics
Added with a phenolic antioxidant to reduce yellowing and property loss during compounding and molding of ABS and HIPS.
What to confirm for your application
- ABS / HIPS grade and other additives
- Heat history in compounding and molding
- Color and impact retention targets
Packaging & Storage
Packaging
25 kg net bags or cartons. Pallet wrapping and private-label bags on request.
Storage
Keep sealed in a cool, dry place away from heat and moisture. See the SDS for full handling details.
Lead time & terms
Typically 3–15 business days from order confirmation, depending on quantity. FOB, CIF or DAP to major ports.
Technical & Buying Information
Antioxidant 168 Buyer Guide
Name the failure you want to prevent
Yellowing or melt-flow change during processing points to the phosphite share; embrittlement or cracking after months in service points to the phenolic and thioester share. Note recycled content and the number of extrusion passes.
Start from a proven blend
Most polyolefin packages start from a phenolic primary plus a phosphite secondary, then adjust. Send your current package and we suggest a starting blend for the trial instead of changing several variables at once.
Compare the numbers that matter
For powders: assay, melting range, volatiles and light transmittance at 425/500 nm (a direct read on color). Ask for the same parameters on our COA that appear on your incoming-inspection sheet.
Lock in supply terms
Agree packaging, monthly volume, destination port and required documents up front. A matching CAS number alone does not qualify a new source; run your trial and keep the approved lot COA as the reference.
Request a Quotation for Antioxidant 168
Start with your polymer, quantity and destination. Add your current grade or specification and we will quote against it.
| Information | Example |
|---|---|
| Polymer / Material | PP, PE, ABS, compound, masterbatch |
| Application | Injection molding, extrusion, film, fiber |
| Current additive | Grade or supplier you use today |
| Required specification | Your TDS, COA or key limits |
| Quantity | Trial order / monthly / annual volume |
| Packaging | Standard 25 kg or specific requirement |
| Destination | Country and port |
| Documents needed | COA, SDS, REACH, food-contact statement |
Related Antioxidants
SUNNOX® 1010
High-MW hindered phenolic primary antioxidant for long-term thermal protection with low volatility.
View product →SUNNOX® 1076
Low-melting hindered phenolic primary antioxidant, easy to disperse in film and compounding.
View product →SUNNOX® DLTDP
Thioester secondary antioxidant that boosts long-term heat aging when used with a phenolic.
View product →SUNNOX® DSTDP
Higher-melting thioester synergist with lower volatility for long-term heat aging.
View product →Antioxidant 168 FAQ
What ratio of 168 to 1010 should I start with?
1:1 and 2:1 (168:1010) are the most widely used starting blends in polyolefins. Use 2:1 when processing stability and color are the main concern, 1:1 when long-term heat aging matters as much. Confirm the ratio in your own trial.
Can Antioxidant 168 be used alone?
It can, but it is not recommended. 168 protects during processing; it does little for long-term aging in service. Pair it with a phenolic primary antioxidant such as 1010 or 1076.
Which COA parameters should I check on incoming lots?
Assay, melting range, volatiles and light transmittance at 425 and 500 nm. Transmittance is the quickest indicator of color quality in the final part.
Can I get a sample before ordering?
Yes. Tell us the polymer, the test you plan to run and the quantity you need. Samples ship with a COA so you can compare the lot against your current material.
What if a COA does not match our agreed specification?
Send us the agreed specification and the COA showing the difference (parameter, unit and test method). We check it with the production batch record before you accept the material, and replace or re-test where the lot is out of specification.
Discuss Your Antioxidant 168 Requirements
Send your application, specification and quantity to request a quotation or supporting documents.