Inverse Emulsion Polymers
Conventional emulsions, in technical terms, are oil-in water emulsions i.e the continuous phase is water. Inverse emulsions are simply the opposite i.e water in oil emulsions with the continuous phase being an oil. Texipol inverse emulsions are manufactured directly from the pre-neutralised liquid monomers that are intimately dispersed in the oil phase followed by a controlled polymerisation process to yield the liquid thickener. The diagram below shows the essential differences between conventional and inverse emulsions.
Mechanism and Benefits of Texipol
Inverse Emulsion Thickeners
When Texipols are added to water or a waterborne system, the Texipol "inverts" with the help of the water soluble emulsifiers and water becomes the continuous phase. The hydrophilic polymer particles swell rapidly and the resulting highly swollen structure leads to a rapid increase in viscosity.
Texipol thickeners are supplied in a pre-neutralised form which means there is no requirement for additional alkali or surfactant to achieve thickening. In most applications, Texipol thickeners can be added at any stage of formulating, including post-thickening of systems, thus allowing greater flexibility when formulating. In general terms a thickener has 3 functions to fulfil in a typical formulation:
- To increase viscosity
- To stabilize the dispersion of insoluble components such as pigments
- To modify the flow.
Alkali Soluble Thickeners
These are dispersions of acid functional acrylic polymers in water. They are supplied at low pH and the acid groups on the polymer chains need to be neutralised to allow the polymer to swell and thicken. Under acidic conditions the polymer has a tight, coil-like structure and after the addition of alkali to the system, the pH increases and the acid functional groups on the thickener begin to dissociate. As a result, the thickener becomes more water-soluble and starts to uncoil. As the pH increases further, the polymer takes on a more open long-chain structure, leading to entanglement of thickener molecules with each other.
Product range information, can be found in our Rheology modifier selection guide supported by our Rheology brochure