Celcon
Celcon is Celanese's proprietary brand of acetal copolymer (POMM-C](/line-card/acetal/pom-c/) — polyoxymethylene copolymer) — one of the original and most widely recognized commercial acetal copolymer resins, available as molding resin and, through compounders, as machined stock shapes (sheet, rod, tube) for precision engineering applications.
TL;DR
| Property | Value |
|---|---|
| Parent material | Acetal copolymer |
| Chemical identity | Polyoxymethylene copolymer (POM-C); includes small percentage of comonomer to improve thermal stability |
| Manufacturer | Celanese Corporation |
| Primary use | Precision machined parts: gears, bushings, cams, valve seats, food-contact components |
| Key differentiator | Better hydrolytic stability and chemical resistance than Delrin (acetal homopolymer); no centerline porosity in large rod |
| Standards | ASTM D4181 (acetal molding compounds); ASTM D6778 (shapes) |
What Is Celcon?
Celcon is a trade name, not a chemical compound. Like Delrin (DuPont's acetal homopolymer brand), Celcon is a brand of polyoxymethylene — but specifically an acetal copolymer, meaning the POM backbone includes a small amount of a comonomer (commonly trioxane + 1,3-dioxolane or ethylene oxide) to interrupt the regular chain structure at intervals. This comonomer insertion:
- Eliminates the "unzipping" degradation that can affect acetal homopolymers at elevated temperature — copolymer chains terminate at the comonomer unit rather than propagating catastrophic depolymerization.
- Improves chemical resistance — particularly to strong bases and hot water (hydrolysis resistance).
- Eliminates centerline porosity — large-diameter acetal copolymer rod can be manufactured without the internal void that sometimes appears in large-diameter Delrin homopolymer rod due to the crystallization front meeting at the centerline.
Celcon grades used in stock shapes include:
- Celcon M90 — standard general-purpose molding resin; the backbone of most Celcon stock shapes
- Celcon M25 — higher viscosity, used for thick-section shapes
- Celcon LW90X — low-warp formulation
- Celcon UV90Z — UV stabilized for outdoor applications
- Celcon GC25 — glass-coupled (glass-fiber reinforced) version for higher stiffness
Key Properties
Celcon (acetal copolymer) has slightly lower flexural modulus and tensile strength than Delrin (acetal homopolymer) at room temperature — typically 5–10% lower. However, Celcon outperforms Delrin in hot water and humid environments and eliminates centerline porosity in large rod cross-sections. For most precision machined parts, the performance difference is negligible; the choice often comes down to stock shape availability, FDA compliance documentation, and supplier preference.
Celcon vs. Delrin: Key Differences
| Property | Celcon (Copolymer) | Delrin (Homopolymer) |
|---|---|---|
| POM type | Copolymer (POM-C) | Homopolymer (POM-H) |
| Manufacturer | Celanese | DuPont (now DuPont Engineering Polymers) |
| Tensile strength | 8,500–9,500 psi | 9,500–10,000 psi |
| Hot water / base resistance | Excellent | Fair |
| Centerline porosity (large rod) | None | Possible in large diameter |
| Thermal stability | Very good | Good (can unzip at high temp) |
| FDA food contact | Selected grades | Selected grades |
| Cost (stock shapes) | Similar | Similar |
The engineering rule of thumb: use Celcon (acetal copolymer) for applications involving hot water, steam, strong bases, food processing equipment, or large rod diameters. Use Delrin (acetal homopolymer) where the highest room-temperature stiffness and dimensional precision are paramount.
Typical Applications
Celcon acetal copolymer stock shapes are machined into:
- Food and beverage machinery components — conveyor chain guides, cam followers, sprockets, and valve bodies in food processing lines. Celcon's hot-water resistance and FDA-compliant grades make it the preferred acetal in USDA/3-A dairy and food-contact environments.
- Precision gears — instrument and light-industrial gears in printers, vending machines, and small appliances. The low friction coefficient against steel allows dry running without lubrication in many duty cycles.
- Bushings and wear pads — self-lubricating bushings in light-load pivots and slides; Celcon runs quieter and with less wear than bronze at equivalent loads.
- Valve seats and pump housings — chemical-handling valves benefit from Celcon's chemical resistance. Avoid strong mineral acids (HCl, H₂SO₄) above 5% concentration.
- Medical device components — selected Celcon grades meet USP Class VI and ISO 10993; used in dental handpieces, surgical instrument housings, and analytical equipment.
- Automotive fuel system parts — Celcon is a standard fuel-contact material; used in fuel pump gears, valve bodies, and quick-connect fittings.
Standard Sizes (Stock Shapes)
| Form | Typical size range |
|---|---|
| Sheet | 1/8 to 2 in. thick; 24 × 48 in. standard |
| Rod | 1/4 to 6 in. diameter |
| Tube | 1 to 6 in. OD; custom wall |
| Colors | Natural (white/off-white); black available |
Stock shapes labeled "acetal copolymer" from most distributors are likely based on Celcon or Hostaform resin — both Celanese acetal copolymer brands.
Standards Reference
- ASTM D4181 — Standard specification for acetal (POM) molding and extrusion materials; Celcon M90 maps to POM Type I (copolymer) in this standard.
- ASTM D6778 — Standard specification for acetal rod, tube, and sheet; references mechanical property minimums for copolymer and homopolymer shapes.
- FDA 21 CFR 177.2470 — acetal copolymer is listed as an indirect food contact polymer; specific grade documentation required.
- ANSI/NSF 51 — food equipment materials standard; Celcon is listed under multiple NSF 51 certifications.
Comparison to Neighbor Materials
| Material | Tensile str. | Hot water | Cost | FDA grades |
|---|---|---|---|---|
| Celcon (POM-C) | 8,500–9,500 psi | Excellent | Low | Yes |
| Delrin (POM-H) | 9,500–10,000 psi | Fair | Low | Yes |
| Nylon 6/6 | 10,000–12,000 psi | Poor (absorbs) | Low | Yes |
| UHMW-PE | 6,000–6,500 psi | Excellent | Low | Yes |
| PEEK | 14,000–16,000 psi | Excellent | High | Yes |
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