Now more than ever there is a need to frequently clean surfaces. Many of the solvent and water-based cleaning solutions used to clean high traffic, often contaminated surfaces are highly acidic or alkaline. In addition, in order for the cleaners to work an extended dwell time on the surface is often required. This can pose a unique challenge for formulators who need to produce a solution with stable viscosity at extreme pH.
Xanthan Gum Thickeners
Xanthan gums are often used as rheology modifiers in water based cleaners due to their inexpensive nature. However, they do not offer the same compatibility and performance in cleaner and detergent formulation that contain solvents. In addition, the anionic nature of xanthan gum makes them incompatible in formulations that contain cations.
METHOCEL™ hydroxypropyl methylcellulose (HPMC) polymers are nonionic, bio-based polymers that are excellent thickeners for water-based and solvent-based household and industrial cleaners and detergents. Much like xanthan gum they are resilient in highly acidic and alkaline systems and produce consistent, stable viscosity from pH 2-13. Unlike xanthan gum, however, METHOCEL™ HPMC are compatible with cationic materials and a variety of solvents commonly used in cleaner and detergent formulations. Some of the typical non-aqueous solvents used with METHOCEL™ HPMC are listed below:
Fufuryl Alcohol
Ethanol
Methanol
Acetic Acid
Propylene Carbonate
METHOCEL™ cellulose ethers are psuedoplastic and impart a shear thinning nature to solutions they are incorporated in. METHOCEL™ allows for solvent based and water based cleaning products to be produced that are stable in a wide pH range, easy to apply, and will remain in place on vertical and overhead surfaces.
METHOCEL™ polymers are very hygroscopic and must be completely dispersed in solution prior to hydration and thickening or else lumps can form. Proper dispersion can be carried out in a few different ways.
Dispersion in Hot Water
This method is also called the "hot/cold" technique and takes advantage of the fact METHOCEL is insoluble in hot water and highly soluble in cool water. METHOCEL™ is dispersed by mixing with 1/3 of the total required volume of water heated to 90 °C. Once all of the METHOCEL™ particles are wetted and dispersed the remaining volume of cold water or ice is added. Once the temperature of the dispersion reaches the point where METHOCEL™ is soluble the particles will hydrate and viscosity increases.
Dry Blending
Dry METHOCEL™ powders can be mixed with other dry ingredients prior to addition to the water component. Dry-blending ensure METHOCEL™ particles are separated and can be completely wetted out and hydrated when water is added. Recommended ratio of dry ingredients to METHOCEL™ powder varies from 7:1 to 3:1.
Dispersion in Nonaqueous Solvents
Direct solubility of most METHOCEL™ grades in nonaqueous solvents is limited. In formulations that utilize water miscible, organic solvents, METHOCEL™ powder can first be dispersed in the organic solvent prior to addition of water. At least 5 to 8 parts of solvent should be used to every 1 part of METHOCEL when preparing dispersions. Addition of water then triggers hydration and viscosity build.
Conclusion
Many household, industrial, and institutional detergents and cleaning formulations utilize acidic or alkaline pH. At higher and lower pH METHOCEL™ thickeners are much more stable than traditional vegetable gums that are used to thicken cleaners and detergents. METHOCEL™ offers much more stable viscosity and thus a longer shelf life for acidic and alkaline cleaning formulations. In addition, METHOCEL™ provides excellent soil redeposition resistance and produces solutions that are easy to apply and cling well to vertical and overhead surfaces. Try METHOCEL™ in your industrial detergent and cleaning formulations today.
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