What Is METHOCEL^™?

Roquette’s METHOCEL^™ cellulose ethers are multifunctional, plant-based ingredients that provide thickening, rheology modification, stability, and film-forming properties in a vast number of chemical formulations. These formulations create various products in industries such as paints, adhesives, cleaners, ceramics, agriculture, food, pharmaceuticals, and cosmetics. Noting the abundance of the different applications METHOCEL^™ can be used in, formulators have several grades to choose from to customize for viscosity, solubility, and food-contact requirements.

What Is METHOCEL^™ Made Of?

METHOCEL^™ is made of either methylcellulose (MC) or hydroxypropyl methylcellulose (HPMC), both of which are water-soluble polymers derived from cellulose that comes from natural wood or cotton linters. Depending on the grade, METHOCEL^™ is made from 65%–87% natural content calculated in accordance with ISO 16128. A chemical diagram of how METHOCEL^™ is derived from cellulose is presented below.
 

Is METHOCEL^™ Safe?

METHOCEL^™ is available in industrial, food-grade, and premium-grade products. The food- and premium-grade products have been extensively evaluated by regulatory bodies from the European Union and the United States to conclude that when used as food additives, they do not have adverse effects on human health at any point in a person’s life, even if consumed daily. This has led to the interpretation that METHOCEL^™ food- and premium-grade products are generally recognized as safe (GRAS).

What Makes METHOCEL^™ Unique?

Many thickeners, rheology modifiers, and film-forming agents may provide one or more similarities in terms of function to METHOCEL^™. None, however, possesses properties that allow for the maximum compatibility, workability, and durability of final products like METHOCEL^™ can. Below is a list of properties that, when combined, make METHOCEL^™ uniquely valuable.

• Shear-thinning rheology modification

Increases the workability of formulations by decreasing viscosity when in motion and increasing viscosity when at rest 

• Reversible thermal gelation

Rapidly increases viscosity at higher solution temperatures, reverting to original viscosity at lower solution temperatures, enabling better “green strength” in certain formulations

• Viscosity control from 15 cPs to 120,000 cPs

Provides a wide range of formulation thickness options

• Stabilization of suspensions and emulsions

Increases the shelf life of formulations containing solid particles and emulsions

• Consistent performance in solutions ranging from pH 3 to 11
• Solubility in water and various organic solvents
• Derived from plant-based materials

What Is METHOCEL^™ Used For?

While METHOCEL^™ is perhaps most well known as a thickener in food and beverage applications, it provides many more functionalities and benefits across various industries. Being derived from cellulose, METHOCEL^™ increases the bio content and sustainability in formulations. Below is a list of a few common industrial applications.
 

Barrier Coatings

Technical Ceramics

Tape-casted Ceramics

Water-based Adhseives

Building Products

Architectural Coatings

Paint Removers

Household and Industrial Cleaners

Agricultural Suspension Concentrates

Suspension PVC

Agricultural Seed Coatings

Several of the functionalities listed above have made METHOCEL^™ a valuable ingredient in several food and personal care applications. In these applications, METHOCEL^™ helps build the desired body, texture, and consistency needed. Certain grades also act as binders to create tablets in pharmaceutical applications. METHOCEL^™ also finds use as a thickener to create the necessary viscosity to simulate solutions for medical research, theatrical props, and more.

How Do I Select a METHOCEL^™ Grade?

METHOCEL^™ should be selected for liquid formulations based on three main criteria: the desired viscosity, the presence of organic solvents, and the need for thermal gelation. These criteria can be identified by the grade nomenclature below.
 
 

Substitution

As introduced at the beginning of this article, METHOCEL^™ cellulose ethers are cellulose polymers with methoxyl and hydroxypropyl functional group substitution. The letter directly following the METHOCEL^™ brand defines both the degree and nature of functional group substitution.
 

The different classifications for substitution above create different degrees of organosolubility and thermal gelation temperatures. Higher hydroxypropyl substitution corresponds with better solubility in organic solvents, and higher methoxy substitution corresponds with a lower thermal gelation temperature.

Viscosity

In general, the viscosity that METHOCEL^™ produces in solutions correlates with molecular weight: larger molecular weight grades produce solutions with higher viscosity and a more pronounced shear thickening effect. METHOCEL^™ viscosity produced in a 2% solution can be distinguished by a number and “multiplier” letter, where “C” is a 100x multiplier and “M” is a 1000x multiplier. “LV” multipliers indicate low-viscosity grades relative to the rest of the portfolio. For example, grade J75MS has a mean viscosity of 75,000 cPs at 2% weight in water. Note that solution viscosity will depend on the concentration of METHOCEL^™ used and the type of solvent(s) used. The graph below shows the viscosity imparted by common METHOCEL^™ grades in DI water at varying concentrations.

 

Below is a graph highlighting the relationship between the molecular weight of METHOCEL^™ and shear-thickening effects, which increase as the polymer’s molecular weight increases.

Shear-thickening effects also become more pronounced as concentration increases, as shown below.

Surface Treatment

METHOCEL^™ grades with an “S” after the “multiplier” letter have been surface treated with glyoxal to enable delayed hydration. Surface-treated METHOCEL^™ polymers will only begin to hydrate and thicken solutions after the pH is adjusted to 9 or above. This allows for METHOCEL^™ easier solution formation if heat sources are not available. See the section titled “How Do I Use METHOCEL^™” for more information on how heat can be used to disperse non-surface-treated grades properly.

METHOCEL^™ Grades

 

How Do I Use METHOCEL^™?

METHOCEL^™ products can be incorporated into solutions or, as they are thermoplastic polymers, can be melt processed into sheets or shapes. If using in a solution, specific procedures should be followed to ensure powders are dispersed properly prior to use.

Untreated Powders

Untreated METHOCEL^™ powders are soluble in cold water and some organic solvents and must be thoroughly dispersed in the solvent to prevent clumping. METHOCEL^™ polymers are not soluble in hot water, and therefore can be properly dispersed by first mixing METHOCEL^™ directly into one-third of the required volume of water heated to approximately 90°C. Then, the remaining liquid volume of the solution can be added as ice or cold water to bring the temperature down, allowing the dispersed particles to hydrate and thicken the solution properly.

For an in-depth look at performing this technique, check out this video.

Surface-Treated Powders

Surface-treated METHOCEL^™ grades can be added directly to pH-neutral water and dispersed with mild agitation. Once dispersed, hydration is triggered by adjusting the pH to 8.5–9.0. Once hydration is complete, the pH of the system can be readjusted, keeping in mind that solutions with METHOCEL^™ are stable from pH 3 to 11.

Where Can I Buy METHOCEL^™?

ChemPoint offers METHOCEL^™ in bags and pallets for industrial applications. Contact us below to ask a question or request a quote or sample.