Naturally occurring cellulose consists of a repeating structure of anhydroglucose units that each contain three reactive hydroxyl sites. In the production of ethylcellulose, these reactive hydroxyl sites are converted into ethyl ether groups to produce a cellulose derived polymer with added hydrophobicity that is useful in many industrial adhesive and coating applications.
Ethylcellulose in Specialty Coatings
Ethylcellulose polymers provide a unique combination of properties that are particularly useful in many types of specialty coating applications for various substrates. Most often it is used to increase the durability and moisture resistance of paper and plastic films. Some common specialty coating applications where ethylcellulose is particularly useful are listed below.
Heat Seal Coatings & Adhesives
Ethyl cellulose is thermoplastic and soluble in most hot polymers, solvents, and oil & wax mixtures used in heat seal formulations. When added to heat seal coatings, ethyl cellulose provides an increase in green bond strength that is especially useful in applications where stresses are applied to a freshly heat sealed joint. Ethyl cellulose provides good adhesion to many plastic films and metal foils that are used in flexible packaging production. Heat seal coatings and adhesives formulated with ethyl cellulose are commonly used for heat sealing packaging for food and pharmaceuticals.
Paper Coatings
Ethyl cellulose is often used as a binder in thin film coatings for paper due to it's combination of flexibility and toughness. Paper coatings formulated with ethyl cellulose provide good gloss, block resistance, and excellent water vapor transmission resistance. Paper products coated with a film of ethyl cellulose exhibit improved moisture resistance and are commonly used for flexible packaging applications.
Glass Coatings & Ink
Ethylcellulose works well as a rheology modifier and temporary binder for solvent-based glass coatings and inks. When used in glass coatings ethyl cellulose helps to improve initial bond strength and is subsequently removed by heating. Ethylcellulose burns out cleanly upon heating leaving behind no residue to interfere with long term adhesion to glass. Because of it's good adhesion and clean burn out, Ethylcellulose is also commonly used for printing inks that must be applied to glass packaging.
ETHOCEL™ Ethylcellulose
ETHOCEL™ is a line of high purity ethylcellulose polymers that are produced to specific molecular weights and ethoxyl content. ETHOCEL™ polymers are manufactured to the highest quality standards and provide best in class purity and batch to batch consistency of any commercially available ethylcellulose polymer. A range of ETHOCEL™ grades are available for use in specialty coating applications to improve the overall durability of the coating formulation.
The viscosity and film properties of ETHOCEL™ is highly dependent on the solvents used in the system. For instance, solutions of ETHOCEL™ in aromatic hydrocarbons are highly viscous, whereas, solutions of ETHOCEL™ in methanol or ethanol have a much lower viscosity at the same concentration. In this example it is also important to note that films formed with ETHOCEL™ in primary alcohols are very brittle and not typically commercially useful. The viscosity and film properties of ETHOCEL™ Std. 10 in common solvents are listed below for reference.
Viscosity & Film Properties of ETHOCEL™ in Various Solvents
Solvent
Viscosity
Specific Gravity
Yield Point
Elongation
n-Butanol
1900 mPa·s
0.848
425 kg/cm²
6%
Butyl Acetate, 90%
590 mPa·s
0.901
430 kg/cm²
7%
Ethanol, Formula 30
560 mPa·s
0.850
*
*
Ethyl Acetate, 99%
360 mPa·s
0.924
440 kg/cm²
9%
Ethylene Dichloride
470 mPa·s
1.238
420 kg/cm²
5%
Methyl Ethyl Ketone
320 mPa·s
0.845
428 kg/cm²
7%
Toluene
1930 mPa·s
0.890
440 kg/cm²
12%
80-20 Toluene-Ethanol
260 mPa·s
0.887
440 kg/cm²
7%
In many formulations the most practical solvents for ETHOCEL™ are mixtures that provide the lowest viscosity consistent with good film properties and that have a suitable evaporation rate. ETHOCEL™ is highly compatible with other components in coating formulations including pigments, dyes, antioxidants, and most modifying polymers.
If you have specific formulation questions ChemPoint is here to help. Contact us today to connect with a coating industry expert to discuss your next specialty coating formulation.
