1. Root causes of high viscosity

1. Tween 80 has a high HLB value of about 15, which is far too hydrophilic.

   The suitable HLB for emulsifying amino silicone oil is only 10～12. Using Tween 80 alone will form a dense network micelle structure, causing sharp thickening and even gelation.
2. 1000 mPa·s amino silicone oil is medium-high viscosity itself.

   Its long molecular chains are easily entangled with highly hydrophilic Tween 80, leading to agglomeration and thickening instead of forming a fluid emulsion.
3. Lack of lipophilic emulsifier to match and adjust HLB.

   Only using Tween 80 without low-HLB lipophilic emulsifier like Span 80 causes serious HLB mismatch. The viscosity rises instantly during phase inversion and gets thicker with stirring.
4. Additional reasons:

   Adding water all at once instead of portion-wise phase inversion; no acetic acid added to neutralize amino groups, resulting in poor dispersion and thickening.

2. Practical solutions (use existing raw materials only)

Solution 1: Compound Tween 80 with Span 80 (most effective)

• Amino silicone oil (1000 mPa·s): 25 parts
• Span 80: 5.6 parts
• Tween 80: 2.4 parts
• Glacial acetic acid: 0.5～0.6 parts
• Deionized water: make up to 100 parts

Solution 2: Adjust production process to reduce viscosity

1. Never add water in one batch

   Add phase inversion water slowly in small portions. Wait until the system turns from thick to thin with blue opalescence, then add the remaining dilution water.
2. Control temperature at 45～55℃

   Mix silicone oil, Span 80 and Tween 80 under heating first to reduce oil viscosity and avoid chain entanglement thickening.
3. Add glacial acetic acid before adding water

   Neutralize amino groups in advance to improve dispersion and prevent agglomeration and pasty texture.

Solution 3: Remedy for already thickened emulsion

1. Heat up to 50～55℃ with slow stirring; avoid high shearing (high shear will cause further gelation).
2. Add deionized water little by little (2%～3% each time), stir evenly before next addition.
3. Add a small amount of glacial acetic acid to adjust pH to 5.5～6.2 for better dispersion and viscosity reduction.
4. Do not add more Tween 80, as it will only make the system thicker.

Summary

Using 1000 mPa·s amino silicone oil with Tween 80 alone inevitably leads to high viscosity and pasty texture due to HLB mismatch and molecular chain entanglement.

The solution: compound Span 80 with Tween 80 at 7:3, control total emulsifier dosage, heat material, add water slowly for phase inversion, and adjust pH with acetic acid in advance, to prepare stable, fluid and non-oil-floating emulsion.