Applications & Uses of Emulsion Polymer

#1 Emulsion Polymers for Adhesive Applications

Adhesives are the second major application field for emulsion polymers. These emulsion-based adhesives surround us in our daily life, for instance:

As packaging adhesives
On the back of sticky-notes and other labels
On the back of the carpets
As glue in several wooden items in our house (furniture or windows)
As binder enforcing the web of the fibers in tissue papers and hygiene articles.

When we live in a modern house, emulsion polymer enforced construction adhesives were most likely applied at the walls and in the flooring or the insulation systems.

Paper & Packaging Adhesives

Paper and packaging adhesives are used to glue corrugated boxes, folding cartons and paper bags. In this market, polymer emulsions benefit from their positive environmental profile based on increasing regulation and customer expectation. The key traits are:

Low content of volatile organic components (VOC)
Non-migration

Many adhesives formulations are required to fulfill FDA food-grade regulations or similar regulations in the regional market. Main application properties to be fulfilled by the polymer emulsions are:

Excellent rheological profile for high machine speed
Good adhesion to difficult-to-bond surfaces, such as polyethylene foil

In many applications, polymer emulsions compete with non-in-kind systems, such as hot melts.

Most of the adhesives contain only 10 – 20% of other additives besides the polymer emulsion. Vinyl acetate homo- and copolymers are the main class of polymer emulsions serving this market, namely:

Vinyl acetate–ethylene copolymer emulsions (VAE):

They are internally plasticized and therefore fulfill all regulatory requirements towards non-migration.
They also have better adhesion to un-polar surfaces such as coated papers or ethylene foil.

Tapes and Labels (PSA)

Adhesives exhibit a certain stickiness and dependence of the adhesion/cohesion balance on the pressure applied. Therefore, they are often also labeled as “Pressure Sensitive Adhesives”.

Key end-use applications include:

Tapes
Labels
Notepads
Automotive trims, and
Dental adhesives

Water-based polymer emulsions are the dominant binder technology in this segment but compete with solvent-based, radiation-cured and hot-melt based systems.

Acrylic-based polymer emulsions are the main polymer type used in this application segment. Their polymer microstructure gives them a favorable adhesion – cohesion balance, which is a key performance factor.

Carpet Backing

Carpet Backing adhesives are used to connect the backing to the face fibers in rugs and carpets.

Polymer emulsions contribute:

Good adhesion
Flexibility, and
Cushioning properties to the application

These formulations are high in inorganic filler content. In general, cost efficiency is on very high demand in this segment. Formulators switch polymer emulsion supplier or type based on cents of cost advantage. At the same time, in time fulfillment of high-volume demands is paramount in this industry.

Even more than for paper and paperboard coatings, this application is the domain of Styrene-butadiene based polymer emulsions that account for 90% of the total volume used for carpet backings.

In this respect, this class of polymer emulsions stands out from the general observed high diversity and versatility. Whilst the other classes serve many segments, about three-quarters of the produced Styrene-butadiene’s, are delivered into only these two segments.

Fiber Bound

Polymer emulsions are also used as adhesives to bind fibers for so-called Non-woven or Engineered Fabrics. These fabrics are used for fem-hygiene products, hygiene towels, diapers, medical fabrics and wipes. Emulsion polymers contribute to:

Dry and wet strength of the fabric
Water repellent properties
Solvent resistance, and
A soft hand of the product

The application is highly regulated, as the products are often indirect skin contact. Extensive testing, registration and approval procedures need to get passed before polymer emulsions can be used in that segment.

Construction

The construction industry is one of the most booming industries in the whole world. Construction adhesives are used in the housing and construction industry, e.g. for flooring or parquet applications, or as caulks and sealants. Technically, polymer-enforced dry mixes for construction can be accounted for in this segment.

Acrylics are the most widely used emulsion in flooring adhesives, as well as, in sealants & caulk applications based on:

Their excellent performance in interior and exterior use.
Their non-toxicity and ease-of-use characteristics.

Also, Vinyl acetate-based co- and terpolymer emulsions, incorporating either Vinyl versate and/or Acrylates, potentially Ethylene, are a good choice for this kind of application.

As non-in-kind technology, silicone emulsions are also commonly used in Sealant & Caulk applications, where they are favored for their insulative properties, chemical resistance, and durability. Only on high alkaline grounds, a pure Acrylic-based system is not favored.

The marketed for polymer enforced dry mix construction adhesives is dominated by Vinyl acetate–ethylene (VAE) copolymer dispersions, which serve the market as re-dispersible dispersion powder (RDP). These powders are made from liquid polymer emulsions by spray drying under the addition of anti-blocking agents and other additives. They are used for:

Tile adhesives
Grouts
Self-leveling grounds
Plasters
Thermal insulation systems
Exterior insulation and finishing systems (EIFS)
Dry mortar
Waterproofing and other applications

Also, Vinyl acetate – Vinyl versate copolymer emulsions can be used.

#2 Emulsions for Coating Applications

Emulsion polymers for coatings find its application in diverse industries, such as:

Housing & construction
Metalworking, or
Paper making and converting

In all cases, the polymer products form a film on the surface, delivering protection, functionality or aesthetical pleasing.

Architectural Coatings

Almost one-third of all emulsion polymers produced are used in the formulation of architectural coatings, often also labeled as “paint”. They are used indoors and outdoors, to add color to our buildings, but also protection against moisture, dirt or mold.

The formulations, the substrates, as well as the requirements, vary depending on the regions and the taste or habits the customers developed. Some substrates that can be used, for instance - wood, concrete, gypsum board, amongst others. The tropical climate put different demand on an architectural coating then ambient or cold climate.

In short, the market and therefore the demands for architectural coatings are highly fragmented.

A typical formulation for an architectural paint consists of:

…aside of the emulsion polymer that contributes only between 5 – 50% of the total mass of the formulation.

For interior decorative application, the most common scheme is to distinguish the paints or applications by the gloss level achieved, that goes along with binder content.

Pure acrylate-based emulsion polymer binders are considered as highest in quality, value, and also price. They are un-competed in high-quality gloss to semi-gloss and satin paints.

When it comes to matt to eggshell type of paints, the filler content is raised, and the function of the emulsion polymer changes, from forming a glossy film incorporating the pigments to binding the fillers and pigments together.

This segment is more sensitive to price, and often pure Acrylic binders are not the best option. Styrene-acrylics, Vinyl-acrylics, and several other types of Vinyl acetate copolymers take the highest share in this segment.

Vinyl acetate-ethylene based polymer emulsions grew an increasing share in this segment over the past two decades, based on their favorable performance in many formulations at comparatively low cost, and their profile as low emission, zero VOC, environmentally friendly binders.

Exterior applications require higher resistance against weather impact and microbiological attack. Depending on technical demands they could be pure Acrylics or Acrylics combined with hydrophobic co-monomers, such as:

Styrene
Methyl methacrylate
Vinyl acetate – Acrylate – VeoVa™10 terpolymer systems, or
Acrylic enforced Vinyl-acetate-ethylene (VAE) polymer emulsions

A Schematic View of Architectural Decorative Paint Segments and Polymer Emulsion Types Used

Paper and Paperboard Coatings

The second biggest segment for the application of emulsion polymers is the coating of paper and paperboard. The formulations are similar to matte paints – high in filler content and pigment. But the processes of application and the technical requirements the coatings have to perform against are completely different.

In general, a paper coat smoothens the fibers of the paper and gives a glossy or matte surface. It also contributes to the behavior of the paper or cardboard during further processing, for example, the brightness and sharpness of printing.

A rather small and narrow particle size distribution is one of the key features a polymer emulsion needs to bring to this application.

The market is primarily served by Styrene-butadienes, which account for more than 70% of the used emulsion polymers. The remainder volume goes in its majority to Acrylics, of which Styrene-acrylics play the most important role.

In the last decade, innovative VAE-based polymer emulsions were developed which take a share from the above-mentioned Styrene or Acrylics-based products, based on their favorable combination of price and performance.

Industrial Coatings

This third major type of coating application is another field dominated by pure Acrylic emulsions based on their high durability and general performance profile. Opposite to the other two sub-segments of coating applications, in this case, the polymer emulsions do not compete mainly in-kind, but with systems based on different polymer types:

Alkyd-, Polyurethane- or Epoxy-based systems, and
Powder coatings

#3 Other Applications

There are many other markets served by polymer emulsions, mainly special applications in niches, such as:

Textile finishing formulations
Latex gloves
Leather finishing, and
Printing inks are the biggest amongst them.

Textile

Emulsion polymers find a wide variety of uses in the processing and finishing of fabrics. Some examples include:

Apparels
Upholstery and furniture fabrics
Fabrics for louver and window blinds

Key functions include:

Sizing
Stiffening
Hand building, and
Semi-permanent finishing

Polymer emulsions used in the textile finishing industry must offer excellent durability and resistance to water and detergents, given the need to withstand laundering and dry cleaning.

Acrylics and Vinyl acetates are the most widely used emulsion polymers in textiles.

Latex Gloves

Emulsion polymers, particularly Acrylonitrile latexes, have seen robust growth in demand in recent years as alternatives to natural rubber in latex gloves.

Nitrile latex gloves for medical and light industrial applications have a number of advantages over natural rubber, including:

Improved protection against solvents and static electricity
Superior puncture and abrasion resistance
Elimination of allergy concerns

Leather Finishing

Leather finishing was one of the first commercial markets for emulsion polymers, dated back to the 1930s. Water-based polymer binders are used in leather finishing to provide a number of useful characteristics, including:

Moisture and abrasion resistance
Texture
Flexibility, and
Durability

Pure Acrylics and Acrylic copolymers are the most widely used emulsion polymers in leather finishing, competing with non-in-kind systems, such as polyurethane dispersions.

The matrix in the table below provides an initial selection guide, of which polymer emulsion type should be chosen for which application.

Application / Polymer Type	Styrene-Butadiene	Styrene-Acrylics	Acrylics	Vinyl acrylics	Vinyl acetates	Vinyl copolymers / VAE
Architectural Paints		Χ	Χ	Χ		Χ
Paper and Paperboard Coatings	Χ	Χ
Industrial Paints			Χ
Paper and Packaging Adhesives					Χ	Χ
Tape and Labels			Χ	Χ		Χ
Carpet backings	Χ	Χ				Χ
Engineered Fabrics						Χ
Flooring Adhesives			Χ	Χ		Χ
Chalks and Sealing Adhesive			Χ	Χ		Χ
Polymer-enforced dry mix						Χ