Acetate (Cellulose Acetate / 醋酯纤维)
Acetate is unique among regenerated cellulose fibers: it is not pure cellulose but a cellulose ester. By acetylating cellulose (replacing hydroxyl –OH groups with acetyl –OCOCH₃ groups), the fiber's chemistry shifts from hydrophilic cellulose toward a more thermoplastic, less absorbent material. This gives acetate properties distinct from all other MMCFs — excellent elastic recovery at low strain, soft drape, and thermoplastic moldability — but at the cost of lower moisture absorption (3.5–6.5%) and more difficult dyeability. Acetate is the second-largest MMCF by volume (~1.1 Mt/year), with the majority (diacetate) used in cigarette filters and a smaller premium fraction (triacetate) used in luxury linings and women's apparel.
Quick Facts
| Type | Regenerated cellulose ester (acetylated cellulose); thermoplastic |
| Chemistry | Cellulose –OH groups replaced by acetyl groups (–OCOCH₃); degree of substitution: diacetate (74–92% acetylated) vs. triacetate (>92%) |
| Raw material | Cellulose pulp (wood or cotton linters) + acetic anhydride → cellulose acetate flakes → dissolved in acetone → dry-spun |
| Commercialized | 1920s (Celanese Corporation); diacetate for filters; triacetate for textiles |
| Global production | ~1.1 million tons/year (~13% of MMCFs; second only to viscose by volume); majority is diacetate for cigarette filters |
| Cross-section | Irregular lobed (多瓣形); no skin-core; smooth surface |
| Moisture regain | Diacetate: ~6.5%; Triacetate: ~3.5% — much lower than other MMCFs (viscose: 12–14%) |
| Density | 1.30–1.33 g/cm³ — lighter than other cellulosics (cotton: 1.54; viscose: 1.50) |
| Thermal behavior | Thermoplastic: softens at 180–205°C (triacetate higher); can be heat-set — unique among cellulosics; melts at ~300°C |
| Key trade names | Eastman Acetate, Celanese, Mitsubishi Rayon, Naia™ (Eastman) |
Diacetate vs. Triacetate
| Property | Diacetate (二醋酯) | Triacetate (三醋酯) |
|---|---|---|
| Acetyl content | 74–92% of –OH groups acetylated | >92% of –OH groups acetylated |
| Dry strength (cN/dtex) | 1.06–1.5 | 0.97–1.24 |
| Wet strength retention | ~55–70% (moderate drop) | ~90% (minimal drop — best among MMCFs for wet performance) |
| Elongation | 25% dry, 35% wet | 25% dry, 35% wet (both high elongation) |
| Moisture regain | ~6.5% | ~3.5% (close to polyester at 0.4%) |
| Elastic recovery (1.5% strain) | ~100% | ~100% — excellent; better than all other MMCFs |
| Heat setting | Possible (thermoplastic) | Better — higher softening point |
| Primary use | Cigarette filters (>90%); limited textile | Textile: luxury linings, women's apparel, ribbons |
Properties (Triacetate for Textiles)
| Property | Rating | Engineering implication |
|---|---|---|
| Elastic recovery at low strain | ★★★★★ Excellent | ~100% recovery at 1.5% elongation — best among all cellulosic fibers; fabrics resist wrinkling at low deformation |
| Wet strength retention | ★★★★★ ~90% | Best wet performance among all MMCFs; triacetate barely weakens when wet |
| Drape and hand | ★★★★★ Soft, fluid | Lobed cross-section + low modulus + thermoplastic finish → soft, elegant drape; luxury aesthetic |
| Moisture absorption | ★★☆☆☆ Low (3.5–6.5%) | Much less than other MMCFs; closer to synthetics; less comfortable in hot conditions |
| Dyeability | ★★☆☆☆ Difficult | Standard dyes don't work on acetylated cellulose; requires disperse dyes (like polyester); limited color range |
| Absolute strength | ★★☆☆☆ Low (1.0–1.5 cN/dtex) | Weakest among major fibers; not for load-bearing applications |
| Thermoplasticity | ★★★★☆ Unique | Can be heat-set, pleated, and molded — the only cellulosic fiber with this capability; used for permanent pleats |
| Heat sensitivity | ★★☆☆☆ Softens 180–205°C | Lower than polyester; care needed in ironing and finishing |
Advantages vs. Limitations
Advantages
- Excellent elastic recovery at low strain (~100% at 1.5%) — best among cellulosics
- Best wet strength retention among all MMCFs (triacetate ~90%)
- Thermoplastic — moldable, heat-settable, permanent pleats possible
- Soft, fluid drape with luxury aesthetic
- Lighter than other cellulosics (density 1.30–1.33)
- Biodegradable (slower than pure cellulose due to acetylation)
- Second-largest MMCF by volume — established supply chain
Limitations
- Very low absolute strength (~1.0–1.5 cN/dtex) — weakest major fiber
- Difficult to dye (disperse dyes only; limited color range)
- Low moisture absorption (3.5–6.5%) — less comfortable than other MMCFs
- Heat-sensitive — softens at relatively low temperature (~180°C)
- Majority of production goes to cigarette filters, not textiles
- Acetone solvent in spinning (volatile organic compound)
- Lower biodegradation rate than pure cellulose MMCFs
Yarn Engineering Guide
| Application | Type | Form | Key criteria |
|---|---|---|---|
| Luxury linings (jackets, coats) | Triacetate filament | Filament weaving; 55–110 dtex | Soft drape; anti-static; breathable; holds pleats; premium positioning |
| Women's apparel (dresses, blouses) | Triacetate filament or staple | Woven or knitted; often blended | Fluid drape; wrinkle resistance at low strain; silk-like aesthetic at lower cost |
| Pleated garments | Triacetate filament | Woven; heat-set pleats | Thermoplastic — permanent pleats possible (unique cellulosic advantage) |
| Ribbons, trims, labels | Triacetate filament | Narrow weaving | Satin-like luster; color fastness (solution-dyed); heat-sealable edges |
| Cigarette filters | Diacetate tow | Continuous filament tow; crimped | >90% of acetate production; absorbency + selective filtration of tar and nicotine |
Summary
Acetate is the odd one out among regenerated cellulose fibers — chemically modified (acetylated), thermoplastic, hydrophobic-leaning, and with unique elastic recovery at low strain. It is the only cellulosic fiber that can be heat-set. Triacetate's niche is clear: luxury linings and soft-drape womenswear where aesthetics trump strength, and where wrinkle recovery at low strain matters more than absolute durability. For the yarn engineer, acetate is a specialty aesthetic fiber, not a workhorse — its value is in hand feel, drape, and thermoplastic processing, not in strength or absorbency. See the Textile Material framework.