Although it is not necessarily linked to cleaning performance, viscosity is culturally associated with the perception of a higher concentration of active ingredients in detergents. Learn which components can provide this attribute, as well as their pros and cons. 

What is viscosity and what is it used for?

Basically, viscosity is a liquid’s resistance to flow. Honey, for example, resists flow more than water. Therefore, we say that honey is more viscous than water.

In hygiene and cleaning products, this characteristic influences consumers’ purchasing decisions due to a cultural factor, since it is believed that the more viscous a product is, the more effective it will be. However, this association is not necessarily true.  

Technically, it can be considered an important factor. Have you ever imagined turning the bottle upside down and having the entire product quickly run off the sponge? Well, then… viscosity helps the product stay on the sponge longer during the dishwashing process.

However, in the case of detergents, this property can be controlled through the use of thickeners, which have no effect on cleaning performance. 

Learn about the different types of thickeners used in detergents

The four main types of thickeners used in the cleaning products industry are: cellulose-based, acrylic, amide, and Noxipon.

HEC thickener  

An example of a cellulose-based thickener is hydroxyethylcellulose (HEC), a nonionic polysaccharide obtained from a purified form of cellulose that reacts with sodium hydroxide to produce alkaline cellulose. The alkaline cellulose is reacted with ethylene oxide to produce a series of hydroxyethyl cellulose esters. 

Advantages:

• High viscosity at low dosages.
• Contributes to suspension formation, stabilization, etc.
• Low variation in viscosity even with temperature fluctuations.
• Low odor.

Cons:  

• It takes time to disperse and tends to form clumps: this makes the process difficult, as it must be added slowly and requires vigorous stirring to ensure complete dispersion.
• It may also require pre-dispersion in another piece of equipment before being added to the final product’s mixing tank.
• The dilution process is influenced by pH and temperature.
• Sticky appearance, like egg whites.

Product with clumping

 

Acrylic thickeners

These are polymers produced from acrylic acid. The most commonly used in detergents are alkali-soluble acrylic thickeners. These are acidic products added during the acid phase that increase the system’s viscosity as the pH rises, reaching their highest viscosity at a pH above 7.0.

Advantages:  

• Produces high-viscosity solutions, especially when combined with sulfonic acid
• Liquid product that is easily diluted in water

Drawbacks:  

• Intense characteristic odor.
• Must be added at a specific pH and requires an additional neutralization step.
• Tends to make the final product slightly opaque.
• Its viscosity fluctuates with temperature changes, drastically altering the product’s appearance at the time of consumption. As a result, it is more difficult to standardize the product’s quality from the consumer’s perspective.

Slightly opaque product

 

Amide - Fatty Acid Diethanolamide

Obtained from vegetable oil or methyl ester treated with diethanolamine, it is available in three concentrations: 60%, 80%, and 90%. The difference between them is essentially the amount of free diethanolamine present in the product.

Any concentration of amide can be used in the manufacture of detergents. The only factor to consider is the cost of use, since the 60% solution is 1.5 times less concentrated than the 90% solution and, for this reason, its price should also be more than 1.5 times lower. Otherwise, the 90% Amide will be the better option, as it will require a lower dosage and take up less space in inventory.

Although this product helps increase the detergent’s viscosity, its main benefit is not necessarily as a thickener, but rather in improving foam quality and emollience (skin protection). To achieve these benefits with Amida, simply add low doses (0.2 to 0.6%).  

Positive aspects:  

• Improved foam quality.  
• Emollient properties (skin protection).

Cons:  

• Reduced solubility of the product, which tends to cause cloudiness issues.
• At high concentrations, they form a film on the surface, visible as a colored stain that is easily noticeable in crystal glasses, for example.
• It does not offer good value for money if used solely as a thickening agent.

Turbid product undergoing separation

 

Noxipon - Technology developed by Macler 

In 1996, Macler launched a new thickening technology on the Brazilian market. The product was named Noxipon. Over the years, some imitations emerged, and alternative names—such as “synthetic amide”—began to be used in the market.

Nonionic and rapidly biodegradable, Noxipon has the ability to significantly increase the thickening power of salts in detergents without compromising stability, offering an excellent cost-benefit ratio.

Advantages:  

• Newtonian rheology, meaning it does not have the gel-like appearance of cellulose-based thickeners
• High translucency
• Low viscosity variation with temperature, compared to acrylic thickeners
• Simplified processing, requiring no neutralization and allowing for rapid dispersion and homogenization at room temperature

Cons:  

• Requires the inclusion of sulfonic acid in the formulation 

Click here to learn more about Noxipon.

Comparison of Different Types of Thickeners

Based on the pros and cons mentioned above, here is the final list of criteria to consider when choosing the best thickener for your detergent formulation: 

Contact our experts to learn how we can provide chemical solutions tailored to your specific needs.