The Importance of Viscosity
The viscosity requirements of a homecare formulation can vary drasticallly depending on the application and is often times critical to both performance and consumer perception of the product. Thickeners and rheology control additives are typically used in homecare formulations to provide formulators precise control over viscosity and "feel" of the final product.
Considerations When Choosing a Thickener
CompatibilityThickening homecare products provides a unique challenge for formulators. Often times these formulations are highly acidic or basic and contain oxidizing agents and surfactants that can be incompatible with thickeners. Selecting a thickener that is compatible with these challenging environments is crucial to producing solution with consistent viscosity and good solution clarity.
RheologyThe rheology, or how a solution behaves under shear stress, is also an important characteristic to consider when selecting a thickening additive. In many homecare applications a thick viscosity is required for cling, dwell time, or to provide a luxurious feel. The high viscosity, however, can make homecare solutions difficult to dispense or spread on surfaces. Selecting a thickener that provides a pseudoplastic (shear thinning) rheology allows for the production of viscous formulations that are easy to dispense and spread.
Usage RateThe amount of thickener required to achieve the desired viscosity can play a large factor in the cost of the formulation. Ideally the thickener that is selected should be the one that provides the targeted viscosity with the lowest usage rate.
CELLOSIZE™ Hydroxyethylcellulose - The Ideal ThickenerCELLOSIZE™ is a line of nonionic, water soluble, hydroxyethylcellulose polymers that are effective thickeners for water-based homecare formulations including liquid hand soap, toilet cleaners, laundry detergent, vertical surface cleaners, and various others. The features and benefits of CELLOSIZE™ hydroxyethylcellulose as thickeners in homecare formulations are listed in the table below.
|Wide Range of Molecular Weights||Allows for precise control of viscosity from thin solutions to gels.|
|Good Chemical Compatibility||Easy to formulate with most surfactants, solvents, gums, and resins. Produces stable solutions with good clarity.|
|Pseudoplastic Rheology||Create viscous solutions with good cling, less dripping, and creamier feel that are easy to dispense and spread on surfaces.|
|Nonionic||Tolerates both cationic and anionic surfactants and salts in the formulation.|
|pH Stability||Stable from pH 2-12. Produces stable viscosity in both acidic and basic systems allowing for formulation flexibility.|
|Viscosity Stability||Improved shelf life and reduction in disposal of expired / out of specification products.|
|Low Usage Rate||Recommended use rates range from 0.5 - 2.0%. Improved efficiency and reduced formulation cost.|
How to Use CELLOSIZE™Hydroxyethylcellulose polymers are hygroscopic powders that will agglomerate and clump when exposed to water if they are not dispersed properly. This can lead to lumpy inconsistent solutions. In order to prevent this CELLOSIZE™ polymers are crosslinked to delay hydration and allow for proper dispersion. The procedure outlined below is recommended for producing stable homogeneous solutions of CELLOSIZE™.
- CELLOSIZE™ should be added under agitation to a solution of pH 7.0 or less
- Allow CELLOSIZE™ to be thoroughly dispersed in the solution
- Once dispersion is achieved the hydration can be accelerated by adjusting the pH to the alkaline range or by increasing the temperature.
- Once hydration is complete and the target viscosity is achieved the solution can be adjusted to a pH between pH 2-12 without any significant effect on viscosity
Selecting a Grade of CELLOSIZE™CELLOSIZE™ hydroxyethylcellulose polymers range in molecular weight and should be selected based on the desired viscosity and the flow properties of the solution. The Brookfield viscosity of various CELLOSIZE™ grades at 2% in water are listed below.
Viscosity @ 2% in Water
300 - 400 cP
4800 - 6000 cP
The concentration of CELLOSIZE™ can be adjusted to meet exact viscosity requirements of a formulation. In addition, the same target viscosity can be reached using different concentrations of various grades.For example, a one percent solution of QP-30000H and a three percent solution of QP-300 both provide a viscosity of 1500 cP, however, the flow properties of the solutions are dramatically different. In general, solutions of large molecular weight grades of CELLOSIZE™ produce solutions with a more pseudoplastic rheology.