pva knowledge
Which PVA grade for High Count Yarns and Polyester Cotton Blends?
High count (fine) yarns and polyester/cotton blended yarns are two major product categories in weaving mills, but their sizing requirements are quite different.
High count yarns (typically 40s and above) are thin, have low strength, and many hairs – requiring good penetration, even coverage, and significant strength improvement. Polyester/cotton blends contain hydrophobic polyester fibres, requiring the size to adhere well to both fibre types.
PVA 1799 vs PVA 0588: Comprehensive Parameter Comparison
In terms of polymerisation degree, PVA 1799 is about 1,700 (high), while PVA 0588 is about 500 (low).
For hydrolysis degree, PVA 1799 is ≥99% (fully hydrolysed), PVA-0588 is about 88% (partially hydrolysed).
Dissolution temperature: PVA 1799 requires hot water above 85°C; PVA 0588 dissolves in cold water.
Film properties: PVA 1799 gives high strength, hardness, abrasion resistance; PVA 0588 gives flexibility and elasticity.
Penetration: PVA 1799 is poor due to large molecules; PVA 0588 is good due to small molecules.
Adhesion to polyester: PVA 1799 is better, PVA 0588 is fair; adhesion to cotton: both are good.
Water solubility/desizability: PVA 1799 is poor, PVA 0588 is good.
Risk of secondary hairs: high when using 1799 alone in large amounts; low for 0588.
Scenario 1: PVA FOR Sizing High Count Yarns
High count yarns have few fibres in the cross section, low strength, many surface hairs requiring effective laying down, and fine diameter requiring high penetration.
Using 1799 alone: though it provides high strength improvement, its poor penetration means the film stays on the surface, leading to stiff handle and difficult splitting. Using 0588 alone: good penetration and flexible film, but relatively low film strength, insufficient strength improvement for high count yarns.
Recommended approach: combine 1799 and 0588. For high count yarns, the combination ensures film integrity and strength. PVA-1799 provides strength; PVA-0588 improves penetration and flexibility – they complement each other.
Suggested ratio: PVA-1799 30%–40%, PVA-0588 10%–20%, modified starch 40%–50%, plus a suitable lubricant.
Practical data show that adding a small amount of PVA 0588 improves sized yarn quality. In trials on pure cotton extra fine high density fabrics, comparing the DH PVA new formulation with the original 1799/0588 blend showed that rational combining maintained sizing quality while improving weaving performance.
Scenario 2: Sizing Polyester/Cotton Blends
Polyester/cotton blends contain two entirely different fibre types. Cotton is hydrophilic, with many hydroxyl groups on the surface to form hydrogen bonds with PVA. Polyester is hydrophobic, with a smooth surface, and adhesion to PVA relies mainly on intermolecular forces. Thus, the size must adhere well to both fibres.
Studies show that PVA 1788 gives the best sizing performance for polyester/cotton blends. However, if we limit the choice to 1799 and 0588, the decision depends on the polyester/cotton ratio.
When the polyester proportion is high (e.g., T/C 65/35 or higher), use PVA-1799 as the main component with 0588 as a supplement, because 1799 has better adhesion to polyester and provides strength. When the cotton proportion is high (e.g., T/C 35/65 or lower), increase the proportion of 0588, as it has better affinity for cotton and stronger penetration. For mills prioritising environmental protection and easy desizing, also increase 0588 because it is more water soluble and yields lower COD.
In recent years, as environmental regulations tighten, research on replacing PVA 1799 with PVA 0588 has drawn attention. Experiments show that, considering size properties, adhesion to polyester/cotton roving, and sized yarn performance, PVA 0588 can partially replace PVA 1799, maintaining sizing quality while reducing environmental impact.
Comprehensive Selection Recommendations
For 100% cotton high count yarns: choose PVA 1788, or combine 1799 and 0588 for both strength and flexibility.
For polyester/cotton blends with high polyester content: use 1799 as main, with 0588 as auxiliary, to ensure adhesion to polyester.
For polyester/cotton blends with high cotton content: choose PVA 1788, or increase the ratio of 0588 for better penetration and environmental performance.
For 100% polyester yarns: use 1799 and 0588 combined, plus a polyester sizing agent.
Conclusion
There is no “best” PVA – only the “most suitable” PVA. High count yarns and polyester/cotton blends have different requirements, and 1799 and 0588 each have their strengths and limitations. The key is to understand the yarn characteristics (fibre composition, count, fabric construction), understand PVA properties (DP determines molecular size, DH determines hydrophilicity/hydrophobicity and film forming behaviour), and combine rationally – since a single model rarely satisfies all requirements, blending is the optimal path. In practice, we recommend conducting small scale trials to validate your selection and find the best combination and ratio for your specific product.
