Viscose Rayon Spinning Technology & Zinc Sulphate ZnSO₄ 98% Acid Bath Control
Industrial Viscose Rayon spinning technology requires rigorous stoichiometric and thermodynamic control of the acid coagulation bath (Müller bath) to develop an optimal skin-core cross-sectional microstructure in regenerated cellulose filaments. Loc Thien Chemical is a Tier-1 Primary Bulk Supplier distributing high-purity Zinc Sulfate (ZnSO₄ 98%, Zn ≥ 35.0%, CAS 7446-19-7) in moisture-proof 25kg multi-wall bags (TANKERS PROHIBITED for dry bulk chemicals), paired with technical-grade Sulfuric Acid H₂SO₄ 98% delivered via dedicated 5–30-ton corrosion-resistant tankers. Divalent zinc ions (Zn²⁺) function as surface crystallization inhibitors and retard xanthate decomposition kinetics, elevating filament tenacity above 2.8 cN/dtex while reducing yarn breakage by 68% at high-speed spinning rates of 120–150 m/min. Direct B2B quotations and lab sample dispatch within 15 minutes via Hotline: 0979 891 929.
1. Viscose Rayon Filament Spinning Overview & Critical Coagulation Bath Function
Viscose Rayon is a regenerated cellulosic fiber manufactured from natural dissolving wood pulp. The process involves alkalization of cellulose with liquid caustic soda (Liquid Caustic Soda NaOH 32%), xanthation with carbon disulfide (CS₂), dissolution into viscose dope, ripening, micro-filtration, and deaeration before extrusion through platinum-gold alloy spinnerets submerged directly into the acid spinning bath.
The Müller spinning bath serves as the physicochemical epicenter of fiber formation. As alkaline viscose dope emerges from thousands of micro-orifices (⌀ 50 - 80 µm) into the strongly acidic liquor, two simultaneous mechanisms govern filament structure:
- Physical Gelation (Salting-Out): Concentrated Sodium Sulfate (Na₂SO₄) dehydrates and precipitates sodium cellulose xanthate from a liquid sol into a cohesive, viscoelastic gel network.
- Chemical Regeneration: Concentrated Sulfuric Acid (Sulfuric Acid H₂SO₄ 98%) neutralizes alkalinity and hydrolyzes xanthate ester groups back to pure cellulose macromolecules, releasing gaseous CS₂ and H₂S.
Without Zinc Sulfate, uncontrolled rapid acidification causes premature crystallization, producing brittle, porous fibers with high breakage rates on downstream godet stretching wheels. Zinc Sulfate (ZnSO₄) is the essential modifier governing delayed coagulation dynamics.
2. Physicochemical Mechanism of Zinc Xanthate Barrier Formation
Upon extrusion, divalent Zn²⁺ cations originating from Zinc Sulfate ZnSO₄ 98% react instantly with surface sodium cellulose xanthate molecules, precipitating a temporary water-insoluble zinc cellulose xanthate membrane:
The zinc xanthate layer (Cell-OCS₂)₂Zn exhibits 15 to 20 times greater resistance to acid hydrolysis than sodium xanthate. This semi-permeable film retards hydronium (H₃O⁺) diffusion into the core, keeping the inner core plastic and stretchable over a 1.5–2.5 meter bath pathlength. Under mechanical godet stretch (50–80%), cellulose polymer chains achieve high uniaxial crystalline orientation, forging a dense outer sheath (skin) and soft absorbent core.
3. Technical Data Sheet (TDS) & Purity Standards for Viscose Spinning Grade ZnSO₄
| Parameter | Zinc Sulfate Monohydrate (ZnSO₄·H₂O) | Industry Spinning Standard |
|---|---|---|
| Assay (ZnSO₄) | ≥ 98.0% | ≥ 98.0% |
| Zinc Content (Zn) | ≥ 35.0% | ≥ 35.0% Active complexing agent |
| Iron Impurity (Fe) | ≤ 20 ppm | ≤ 50 ppm (Prevents yarn discoloration) |
| Heavy Metals (Pb, Cd) | ≤ 5 ppm (ICP-OES verified) | ZDHC MRSL v3.1 Compliant |
| Water Insoluble Matter | ≤ 0.02% | Prevents spinneret orifice clogging |
| Packaging Specification (SSOT) | 25kg multi-wall paper bags with inner PE liner (TANKERS STRICTLY PROHIBITED) | |
4. Spinning Bath Operational Control Matrix
| Component | Target Concentration | Technical Impact |
|---|---|---|
| Zinc Sulfate (ZnSO₄) | 12 ~ 18 g/L | Generates durable skin-core structure; maximizes elongation |
| Sulfuric Acid (H₂SO₄) | 110 ~ 135 g/L | Supplied via 5–30-ton tankers for continuous bath rejuvenation |
| Sodium Sulfate (Na₂SO₄) | 280 ~ 340 g/L | Dehydrates viscose dope through rapid salting-out |
| Bath Temperature | 48°C ~ 52°C | Governs mass transfer and ionic diffusion rates |
FDI plant engineers can utilize Loc Thien Chemical Online Dosage Calculator to simulate bath chemical replenishment rates based on daily tonnage.
5. B2B Case Study: 50,000 Tons/Year FDI Viscose Plant in Nhon Trach IZ
Eliminating High-Speed Yarn Breakage and Boosting Output by 18%
- Background: A Taiwanese-invested synthetic fiber complex in Nhon Trach Industrial Park (Dong Nai) suffered high yarn breakage (4.2 breaks/ton) when increasing line speed from 110 to 140 m/min due to substandard Zinc Sulfate containing variable zinc concentration and micro-solids.
- Loc Thien Solution: Standardized supply of high-purity ZnSO₄ 98% (Zn ≥ 35.0%) in 25kg bags and technical H₂SO₄ 98% delivered via 25-ton dedicated tankers, maintaining bath Zn²⁺ precisely at 15.5 ± 0.5 g/L.
- Operational Results:
- Yarn breakage dropped from 4.2 to 1.3 breaks/ton (68% reduction).
- Fiber tenacity increased from 2.45 to 2.82 cN/dtex.
- Elongation stabilized at 18.5% ± 0.5%.
- Spinning machine speed operated smoothly at 145 m/min, boosting total plant capacity by 18% monthly.
- For associated textile effluent compliance, review our ZDHC MRSL v3.1 textile wastewater treatment technology with FeCl2.
6. Chemical Safety & Warehouse Logistics Specifications
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⚡ Request Zinc Sulfate 98% & H₂SO₄ Spinning Bath Quotation (15-Minute Response)
Loc Thien Chemical maintains 500+ tons of Zinc Sulfate inventory and 5–30-ton tankers for immediate delivery across Vietnam.
- Technical Engineering Hotline: 0979 891 929
- Official B2B Email: [email protected]
- Packaging Standard: Zinc Sulfate 25kg bags (Tankers Prohibited) | H₂SO₄ 5–30-ton tankers.