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Methods for Industrial Water Treatment to Enhance Polyolefin Dispersion Stability

IP.com Disclosure Number: IPCOM000224391D
Publication Date: 2012-Dec-17
Document File: 2 page(s) / 22K

Publishing Venue

The IP.com Prior Art Database

Abstract

A polyolefin dispersion usually comprises a polyolefin polymer, an anionic dispersing agent and water. Stability of the polyolefin dispersion is largely dependent upon how effective the dispersing agent is. Due to the nature of ionic charges, this dispersion becomes unstable when it is exposed to multivalent cations. If untreated industrial water is utilized to dilute the polyolefin dispersion to prepare it for application, the polyolefin dispersion may become unstable and may crash out of the dispersion. This instability is believed to be due to formation of cross-linking points between multi-valent cations, such as calcium ions in industrial water, and the anionic functional groups on the dispersing agent. Instability of the polyolefin dispersion in industrial water prevents the dispersion from being recycled and reused which increases cost significantly.

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Methods for Industrial Water Treatment to Enhance Polyolefin Dispersion Stability

A polyolefin dispersion usually comprises a polyolefin polymer, an anionic dispersing agent and water.  Stability of the polyolefin dispersion is largely dependent upon how effective the dispersing agent is.  Due to the nature of ionic charges, this dispersion becomes unstable when it is exposed to multivalent cations.  If untreated industrial water is utilized to dilute the polyolefin dispersion to prepare it for application, the polyolefin dispersion may become unstable and may crash out of the dispersion.  This instability is believed to be due to formation of cross-linking points between multi-valent cations, such as calcium ions in industrial water, and the anionic functional groups on the dispersing agent. Instability of the polyolefin dispersion in industrial water prevents the dispersion from being recycled and reused which increases cost significantly.

There are two ways to overcome this challenge: use of purified water which may increase cost or reformulate the polyolefin dispersion so that it has improved stability while maintaining the use of industrial water for the low cost benefit.  For water purification approach, there are three methods to remove the multi-valent ions from industrial water: (1) distillation, (2) reverse osmosis (RO), and (3) water softening.  In all cases, industrial water has to be first treated and then be used in industrial applications which involve the use of equipment to handle water transportation and storage, and further energy to separate the ions from water. 

Distillation is a method of separating mixtures based on differences in volatilities of components in a boiling liquid mixture.  In water purification case, since the ions in water are not volatile, we just need to evaporate water at its boiling point and then collect it by cooling/condensation.  This method requires a lot of energy since water has a very high specific heat. 

Reverse osmosis is a membrane-technology filtration method that removes many types of large molecules and ions from solutions by applying pressure to the solution when it is on one side of a selective membrane.  The result is that the solute (i.e., ions) is retained on the pressurized side of the membrane and the pure solvent (i.e., water) is allowed to pass to the other side.  To be “selective”, this membrane should not allow large molecules or ions through the pores, but should allow smaller component of the solution (such as water) to pass freely.  The process is similar to other membrane technology applications.  However, there are key differences between reverse osmosis and filtration.  The predominant removal mechanism in membrane filtration is straining, or size exclusion, so the process can theoretically achieve perfect exclusion of particles regardless of operational parameters such as influent pressure and concentration.  Reverse osmosis, however, involves a diff...