Water Dispersible Sulfopolyesters - AQ™ Polymers & Eastek™

Aromatic polyesters like polyethylene terephthalate (PET) are some of the most commonly used materials for packaging and textiles.  They are strong, durable, and relatively safe.  Water-dispersible sulfopolyester resins from Eastman provide all of the benefits of an aromatic polyester in an easy to disperse resin or water-based dispersion.  AQ™ polymers and Eastek™ dispersions have all of the physical properties needed to perform in coating, ink, adhesive, personal care and textile sizing applications.  

Eastman AQ™ polymers, also known as polyester-5, come as solid resins that are polymerized using glycols and aromatic diacids.  The same water-based resins are available in dispersion form under the Eastek™ trade name allowing formulators the flexibility of working with a solid resin or a water-based dispersion.

When choosing a sulfopolyester resin, or any film forming resin, there are some key physical properties that need to be considered based on the application.  These properties can be optimized by choosing the correct resin for the job.

Viscosity
The viscosity of sulfopolyester dispersions is dependent on percent solids of the dispersion.  Unlike solution polymers like PVOH and PVP, dispersions of AQ™ polymers have a relatively low viscosity (less than 100 cP) up to 30% solids.  Above 30% solids viscosity will increase rapidly with concentration much like a latex.

Minimum Film Forming Temperature and Drying Time
The minimum film formation temperature of typical dispersions is usually equal to the Tg of the dispersed polymer.  In order to reduce that temperature a plasticizer or coalescent must be added.  Because sulfopolyesters are plasticized by water the minimum film formation temperature is about 20°C less than the Tg of the polymer and film formation will occur without the presence of a coalescent.  A lower film formation temperature and the small nature of the polymer aggregates lend to AQ™ polymers having a very rapid drying time.

Tack and Flexibility
AQ™ polymers and Eastek™ dispersions range in Tg from 3°C up to 63°C.  Sulfopolyesters with a Tg over 45°C form thin films that are rigid with low tack.  Inversely, sulfopolyesters with a Tg of less than 35°C form flexible films with moderate tack.

Water & Humidity Resistance
The water and humidity resistance of sulfopolyester films is inversely related to the charge density of the polymer; low charge density polymers are more resistant than high charge density polymers.  Water resistance can also be increased or decreased by the addition or hydrophobic and hydrophilic plasticizers.  Additionally, sulfopolyesters do not disperse in solution with high ionic strength therefor they show excellent resistance to bodily fluids like sweat.  This proves to be very useful in personal care applications.

Gloss
Dispersions of sulfopolyesters have very small particle aggregates.  Because of that films formed from sulfopolyesters have a very smooth glossy appearance.  Conventional matting agents like clay or silica have proven to work well with sulfopolyester is a matte appearance is desired.

Coatings & Inks
The broad Tg range of AQ™ polymers allows for the formulation of coatings and inks with varying flexibility and tack.  Additionally, the rapid film formation of sulfopolyesters make AQ™ polymers an ideal resin for formulators looking to streamline the process of printing and coating operations.  Eastek™ dispersion take that one step further by providing a pre-dispersed option.

Personal Care & Cosmetics
Eastman AQ™ polymers, or polyester-5, are commonly used ingredients in cosmetics, lotions, and hair care products.  AQ™ 38S is used in sun screens to help improve the water and sweat resistance and allow improved duration of UV protection while providing a non-oily feel to the product.  AQ™ 48 Ultra was designed specifically to be used as a hair fixative in hair sprays and gels.  It provides excellent hold, sweat resistance, and has great wash out with shampooing.  AQ™ 55S is the preferred polyester-5 to improve water and smudge resistance of makeup. 

Hot Melt Adhesive
AQ™ 1950 was designed to be used as a resin in repulpable hot melt adhesives.  Because of it's low Tg AQ™ 1950 has good tack, flexibility and will adhere to most common packaging films including paper and PET.  The charge density and unique water dispersibility make AQ™ 1950 completely repulable and provide for easier recycling of packaging materials.

Textile Sizing
The smooth and flexible nature of films formed from lower Tg sulfopolyesters make for excellent textile sizing.  Eastek™ 1000 and AQ™ 38S coatings provide the optimum level of flexibility and slip needed to protect yarns from the stresses applied during weaving.  Yarns sized with sulfopolyesters are stronger and will break and rupture less frequently allowing for increased productivity of weaving processes.