In the formulation development of fabric softeners, viscosity stability is often a critical factor determining whether a product can be launched onto the market. The phenomena of thinning, separation, or gelation after low-temperature freeze-thaw cycles, or a dramatic drop in viscosity during high-temperature storage, have long been persistent challenges for formulators.
HonesoftⓇ SP-90, a long-chain ester-based quaternary ammonium salt with exceptional thickening potential, demonstrates remarkable stability across the entire temperature range when used in conjunction with the specialized cationic thickener ZW-001. The following experimental data reveals the secrets behind this performance.
Ⅰ.Basic rheological properties: The synergistic effect of SP-90's self-thickening behavior with ZW-001
-- We first compared the rheological behavior of SP-90 in a 5% solution (see Table 1).
Table 1: Viscosity comparison of SP-90 5% solution under different thickening conditions
|
Serial No. |
Formula Composition |
Viscosity (mPa·s) |
Measuring Temperature |
|
Formula 1 |
SP-90 (330 g) + Thickener ZW-001 (3.00 g) |
740.9 |
26°C |
|
Formula 2 |
SP-90 (330 g) + Thickener ZW-001 (3.94 g) |
1038 |
26°C |
|
Formula 3 |
SP-90 (330 g) + 0 g (Blank Control) |
13.41 |
26°C |
-
Data Interpretation
1. Self-thickening base: SP-90 inherently possesses a certain degree of self-thickening capability; however, on its own, it exhibits extremely low viscosity (only 13.41 mPa·s).
2. Synergistic effect: Upon addition of a small amount of ZW-001, the viscosity increases exponentially. A dosage of 0.91% achieves a viscosity of 740.9 mPa·s; when the dosage reaches 1.2%, the viscosity effortlessly exceeds 1000 mPa·s (1038 mPa·s). This demonstrates that SP-90 and ZW-001 exhibit an excellent synergistic thickening effect, enabling the creation of an ideal fluid structure with an extremely low dosage.
Ⅱ.Extreme Environmental Challenges
-- Viscosity Retention Rate Under Freeze-Thaw and Thermal Storage Conditions – Simply having high viscosity is not enough; the real challenge lies in maintaining stability under extreme environmental conditions. We conducted rigorous freezing tests at –18°C and high-temperature tests at 50°C on the aforementioned formulation; the results are as follows:
Table 2: Stability test of the SP-90 + ZW-001 system at different temperatures
|
Formula No. |
Initial Viscosity (mPa·s) |
Temperature |
Re-test Viscosity (mPa·s) |
Viscosity Retention Rate |
Visual Observation |
Single Judgment |
|
1 |
740.9 |
–18°C (Frozen) |
1038 |
140.1% |
Slight gel formation observed |
Disqualified |
|
1 |
740.9 |
25°C (Room Temperature) |
810.8 |
109.4% |
No gel or layering observed |
Qualified |
|
1 |
740.9 |
50°C (High Temperature) |
810.4 |
109.3% |
No gel or layering observed |
Qualified |
|
2 |
1038 |
–18°C (Frozen) |
1038 |
100.00% |
No gel or layering observed |
Qualified |
|
2 |
1038 |
25°C (Room Temperature) |
1038 |
100.00% |
No gel or layering observed |
Qualified |
|
2 |
1038 |
50°C (High Temperature) |
1038 |
100.00% |
No gel or layering observed |
Qualified |
|
3 |
13.41 |
–18°C (Frozen) |
106.279 |
- |
Emulsion agglomeration observed |
No evaluation |
|
3 |
13.41 |
25°C (Room Temperature) |
14.55 |
108.50% |
Reference sample |
No evaluation |
|
3 |
13.41 |
50°C (High Temperature) |
11.99 |
58.945% |
Reference sample |
No evaluation |
Ⅲ.The Technical Value Behind the Data
For Formula No.2 (high-thickening system), the viscosity retention rate remains as high as 100% after storage at 50°C. For Formula No.1, the viscosity retention rate also reaches 109.38%. This means that even during hot summer logistics transportation or warehouse storage, products formulated with the SP-90 system will maintain their viscosity without any degradation or occurrence of the "becoming thinner over time" phenomenon.
This is the most noteworthy piece of data. After freezing at –18°C, Formula No.2 maintained a viscosity retention rate of 100% with no gel formation or layering observed. In contrast, Formula No.1 exhibited slight gelation after freezing (with its viscosity abnormally increasing to 140%). This demonstrates that appropriately increasing the dosage of ZW-001 (e.g., 3.94 g for Formula No.2) can facilitate the formation of a more robust network structure, effectively mitigating the risk of gelation induced by low temperatures and ensuring product stability during extreme cold conditions in Northeast China or during cold-chain transportation.
Formulation 3 (without thickeners) exhibited severe emulsion aggregation after freezing. Although the viscosity value surged, this phenomenon served as a precursor to demulsification. This highlights the significant advantage of the SP-90 + ZW-001 system in terms of physical stability.
Ⅳ.Conclusion
Data does not lie. The HonesoftⓇ SP-90, when combined with the cationic thickener ZW-001, forms a high-viscosity, highly stable lubricant matrix.
● Room temperature: Provides a smooth, substantial texture.
● High temperature (50°C): Nearly zero viscosity loss – no concerns about shelf life.
● Low temperature (-18°C): After optimizing the formulation ratio, the gelation risk is completely eliminated, ensuring freeze-thaw stability.
--Choosing HonesoftⓇ SP-90 means not only selecting an exceptional soft active ingredient but also opting for a rigorously validated viscosity stabilization solution.
If your product is intended for distribution to cold northern regions, it is recommended to refer to the thickening agent proportion specified in Formula No.2 to achieve optimal stability across all temperature ranges.
Want to learn more about how Honesoft® SP‑90 paired with ZW‑001 can solve your fabric softener formulation challenges with freeze‑thaw and high‑temperature viscosity stability? Get in touch with our technical team today for formulation recommendations, sample support and custom technical guidance.
