Will Thiourea Dioxide Damage Polyester Fabric?
Direct Answer
Direct Answer Not under recommended conditions. It can cause damage if temperature, time and alkali charge run out of control, so the boundaries are worth stating clearly.
Why it is safe under normal conditions
Polyester is a hydrophobic synthetic fibre. It tolerates alkali but is not alkali-proof. Thiourea dioxide itself is a reducing agent, not an alkali. What actually costs polyester weight is the caustic soda in the system combined with high temperature, not thiourea dioxide.
When damage does occur
- Excessive temperature with long dwell, for example well above 120 C for a prolonged period, causes alkaline hydrolysis and weight loss
- Excessive caustic soda etches the fibre surface, showing up as weight loss, lower tensile strength and a harsher handle
- Repeated stripping or multiple reduction clears cause cumulative damage
- Running in the same bath as strong oxidisers without an intermediate rinse
Control points
| Parameter | Suggested range |
|---|---|
| Temperature | 70 to 95 C for reduction clearing; boiling for stripping |
| Time | 20 to 30 min for reduction clearing; 20 to 60 min for stripping |
| Caustic soda (38 Be) | 2.0 to 4.0 ml/L for reduction clearing; 8.0 to 15.0 ml/L for stripping |
| Aftertreatment | Drain promptly and rinse hot |
How to verify
In the bench trial weigh the fabric bone dry before and after treatment to get weight loss, and measure retained tensile strength. Weight loss below 1% with strength retention above 95% normally means no material damage.
Bottom line
Control temperature, time and alkali charge as in the table above and polyester is not damaged. What needs guarding against is high temperature combined with high alkali, not thiourea dioxide itself.
Sources
- 我司产品技术数据表《THIOUREA DIOXIDE Technical Data Sheet》（TDO-TDS，签发日期 2024-05-08）
- Effective reduction clearing parameters involving alternative reducing agent（2021），DOI 10.54693/piche.04916
- Performance Evaluation of Hydrose and Thiourea Dioxide as Stripping Agents for Reactive Dyes，AJER 7(2), 2018，https://www.ajer.org/papers/Vol-7-issue-2/ZF070201250258.pdf
Need a sample, COA, SDS or technical support? Contact Dasteck.