Water-based adhesives are versatile, and they provide advanced bonding to meet demanding applications in a wide variety of end-use markets. As a leader in developing adhesives solutions across industries, Henkel is one of the most trusted of all water-based adhesive manufacturers. The products in our AQUENCE® range of water-based adhesives are coater-ready, while superior finishes allow our customers to maintain product quality and improve total cost of ownership. 

Henkel water-based adhesives are used to create a variety of products including books, home appliances, medical tape, and packaging. Our adhesives are selected because they solve many of the problems faced by manufacturers including label flagging and adhesive transfer. Manufacturers can choose from adhesives based on different polymers to find the solution that perfectly suits their products. 

To learn more about our products or obtain industry-specific information on our water-based adhesives, contact a member of our team.

Water-Based Adhesive Chemistries

Water-based adhesives are developed using a combination of water, polymers, and additives. They are ideal for porous or non-porous substrates. These adhesives may be formulated as solutions and are activated as the water evaporates or is absorbed by the substrate. There are several different chemistries – both natural-based and synthetic-based materials – these include:

  • VAM-based emulsions (VAE or PVA emulsions)
  • Acrylic-based emulsions
  • Natural based or bio-based adhesives
  • Natural rubber adhesives
  • Liquid polyurethane – structural engineering and food packaging/flexible laminates (LIOFOL)
  • Additives for water-based adhesive applications

VAM-Based Emulsion Adhesives

There are two primary types of VAM-based emulsions. The first is polyvinyl acetate (PVA) adhesives. They are aliphatic, rubbery synthetic polymers and are considered a type of thermoplastic. PVAs are designed for use on porous materials, particularly paper, wood, tissue, nonwovens, cloth, and some stone materials. Paper applications, such as corrugated board, bookbinding, envelopes and labelling are the most common uses.

The second is Vinyl Acetate Ethylene (VAE) adhesives. They offer considerable performance advantages over PVA adhesives. VAE adhesives offer comparable machining properties to PVAs with improved adhesion to non-porous surfaces. VAE adhesives have better flexibility and water resistance with superior bonding properties.

Flexible packaging is the biggest application type for VAE adhesives. Another large category is laminating applications due to their flexibility, moisture resistance, and superior substrate adhesion. VAEs are widely used in furniture, bookbinding, and textiles applications. VAEs are also popular in the fabrication of nonwoven products, such as personal hygiene applications.

Acrylic-based Emulsion Adhesives

Acrylic-based emulsion adhesives are made by homogeneously emulsifying vinyl acetate, EVA, or acrylic synthetic resin polymers in water. These adhesives provide a balance between:

  • Peel – the strength between the adhesive and the substrate, increasing over time during the curing process
  • Shear – the ability for the product to adhere to itself
  • Tack – the speed the adhesive bonds immediately to the substrate

Many acrylic polymers are crosslinked, which improves the weather and aging resistance, as well as preventing breakdown by other solvents. Some common acrylic adhesives include pressure-sensitive adhesives and paper laminating adhesives. Acrylic-based emulsion adhesive is commonly used to manufacture packaging, particularly paperboard boxes.

Natural-based or Bio-based Adhesives

Natural-based polymers are developed from organic materials. Some of the most popular are derived from vegetable sources, such as starches and dextrins, or protein sources, such as soybeans, casein, and milk albumen. Natural-based adhesives with caseins have relatively long drying times, form very strong bonds, and are resistant to water. Dextrins are commonly used in the paper industry and very durable with specific materials. However, they are susceptible to breakdown when exposed to water.

Natural-based or bio-based adhesives are supplied in 2 forms – liquid solutions or as dry powders – both are mixed with water prior to application. Adhesive strength results when water evaporates or absorbs into the substrate. Common applications involve a permeable substrate; however, there are other methods involving dry time before the adhesive can be activated with a “quick tack” joining two non-permeable substrates. Many natural-based adhesives are perishable and extended storage is not possible.

Natural Rubber and Polychloride Adhesives

Natural rubber adhesive is one of the earliest substances used to bind materials. Because of its capacity to become elastic when heated, it is one of the most popular adhesives on the market and is typically used in bonding organic and porous materials such as leather, paper, fabrics, as well as other rubber products. 

Natural rubber adhesives offer aggressive and instantaneous tack and have a lower toxicity level. For these chemistries, tackifiers must be added to achieve different levels of adhesion. Rubber-based adhesives offer water-resistant properties, flexibility, and versatility, making it a good choice for use in clothing and footwear manufacturing, as well as for reinforcing the backing of carpets and floor rugs.

Liquid Polyurethane Adhesives

Designed for use in extreme environmental conditions, liquid polyurethane (PUR) adhesives are reactive moisture curing. The chemistry enables the adhesive to bond with low, surface energy substrates which are difficult to bond. Their attributes include strong bonding and exceptional cold, heat and moisture resistance. These adhesives are commonly found in flexible packaging applications.

Liquid polyurethane adhesives produce extremely durable, highly elastic bonds. Reacting to the moisture in the environment, these adhesives form a cross-linked, thermoset bond. They have short open times, are easy to apply, and are simple to clean-up. These chemistries are designed for adhering materials such as – carpet, wood, foam, metal, and most plastics to each other. They are not recommended for vinyl (PVC), polypropylene, polyethylene, and polyolefins.

Additives for Water-Based Applications

Some water-based adhesives contain additives such as surfactants and emulsifiers to stabilize the chemistry. Other ingredients are sometimes added include defoamers, biocides, pigments, flame retardants, anti-static, and wetting agents to support different performance needs of the adhesive.

Commonly part of water-based adhesive formulations with paper packaging applications, additives play an important role in the various paper application process. The most common additive is water resistant resin. These formulations render the formula moisture resistant or waterproof. These additives crosslink with starch molecules making it more difficult for water to dissolve the mix.

Adhesive with water-resistant additives (WRA) should be used within a certain timeframe after the crosslinking agent is added. In many cases, a dye is incorporated into the formulation to give operators a visual cure the additive was added to the adhesive. When working with additives, manufacturers should consideration the following:

  • Using fresh adhesive (less than 4 hours after adding resin)
  • Targeting a viscosity between 32–38 seconds
  • Achieving higher solids (26% +) gives better results

Water-Based Adhesive Product Forms

High-quality water-based adhesives are extremely quick and easy to apply. They can be applied via rollers, spray guns, and using immersion processes. Water-based adhesives do not adversely impact rollers and other equipment as they dry. Water-based adhesives are also easier to remove from equipment, further minimizing the risk of blockages. Water-based adhesives are delivered in bulk containers, such as:

  • Drums
  • Totes
  • Tank truck

Depending on the product, there are different concentration levels. This requires some effort to dilute the products to meet the application needs. In some cased, there are two-part systems. These require additional effort to mix the adhesive for each application.

Water-based adhesives also have different viscosities – defined by application. They range from flowing like water up to more viscos options similar to molasses. Viscosity is measured by centipoise (cPs) – essentially this is the thickness of a water-based adhesive. The higher the cPs, the thicker the substance. Water is measured at 1 cPs, castor oil is 1,000 cPs, and peanut butter is 250,000 cPs.

Water-Based Adhesive Equipment

Water-based adhesives work with a different range of equipment applications. Each have many unique properties. Some of the primary equipment includes:

Merlin Dilution System

Concentrated water-based adhesives are used in various markets. There is not an industry standard for diluting the adhesives to the desired percent solids or viscosity, which can cause variations in the performance and use. The Merlin Dilution System is an on-line adhesive dilution system for concentrated adhesives which provides a completely automated process and replaces the current manual practice of dilution. Adhesive is supplied “On Demand” from storage tanks. It eliminates heavy lifting and dumping pails, which keeps line operators from chemical exposure.

Primarily used by tissue and towel manufacturers, the Merlin Dilution System:

  • Eliminates risk of contamination
  • Controls/adjusts adhesive concentration
  • Matches percent solids to processing requirements
  • Reduces variability in adhesive concentration

Extrusion Transfer System

Softness and absorbency are important consumer demands for tissue and towel products. Achieving quality is often sacrificed with efficiency on tissue and towel production lines. Open-pot operations face challenges of slinging and maintaining the adhesive properties. The extrusion transfer system is a popular investment supporting a cleaner and more efficient production line.

Installing an extrusion transfer system eliminates the need to clean/remove the pot and reduces safety risks associated with equipment cleaning. Another benefit is manufacturers can utilize higher performance adhesives tailored for specific production needs. Results from numerous system installations include:

  • Improved run time 5 – 22 minutes per 12-hour shift
  • Reduced add-on rates 15 -50%
  • Reduced waste 35 - 50%
  • Improved operator safety from reduced clean up

Water-Based Adhesive Monitoring Systems

Understanding the adhesive usage – application levels and environmental factors – provides operational insights for water-based adhesive applications. Designed with a series of sensors feeding real-time data to a dashboard which enables optimization of adhesive consumption and reduction of downtime on the production line. The system can also notify operators of any failure or malfunction of the water-based adhesive equipment.

When an active batch is currently on the production line – running or not – basic information is displayed. This data includes start time, end time, if the batch is finished and general information on the water-based adhesives (e.g., brand, adhesive name and identifying numbers). This provides the operator with pertinent details and allows recognition any discrepancies with the factory condition. Henkel’s monitoring systems perform:

  • Environmental condition to assure optimal adhesion
  • Consumption details to assure application amounts are within range
  • Data on the affixing process to identify interruptions and track efficiency

AEROBOND Foaming Technology

Laminating and corrugating adhesive applications require a precise balance of moisture in the adhesives used.  If the density is off – the result is either warped corrugate or layer curl. The AEROBOND Foaming technology injects air into the adhesive stream to reduce the density, which in turn reduces the amount applied.  Additionally, the rheology is improved and assures the adhesive remains where applied.

Foaming is a key component for thin-film metering systems used in litho-laminating applications. To maintain the highest possible operating speed, the adhesive needs a “high wet tack” to prevent edge lift. Reducing the adhesive density allows manufacturers to operate at the highest possible machine speed with little or no delamination or edge lift. Foaming also enables 100% fiber tear.

Contact us to find out more about any of our equipment or get industry-specific information on our water-based adhesives, contact a member of our team.

Industrial Applications for Water-Based Adhesives

Water-based adhesives contain an organic binder (most commonly PVAc) that is finely dispersed in water. When this water evaporates or is absorbed into the substrate, the adhesive will be left behind, bonding the two surfaces together. Water-based adhesives are a particularly good choice for adhering porous substrates like paper, cardboard, textiles, woods, and some plastics.

When using a high-quality water-based adhesive, manufacturers get many of the benefits of solvent-based adhesives with a few added advantages. These include lower costs and lower VOCs. Water-based adhesives are also safer to use and better for the environment than solvent alternatives.

Furniture and Building

Improving the quality, efficiency, and sustainability of furniture and building components is important. Henkel’s water-based adhesives bond a variety of wooden parts in many applications for furniture, mattress building applications.

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Personal Hygiene

When it comes to health, wellness and comfort, consumers want quality. Henkel manufactures water-based adhesives for hygiene and nonwoven industry focused on high adhesion with skin-friendliness to deliver security for each application.

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Food and Beverage

Versatility makes water-based adhesives one of the most popular options for labeling consumer packaging. As a labeling option for consumer packaging adhesives increase line speed and minimize material waste.

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Tapes and Labels

Sustainability and security are key elements of tape and label applications. Henkel’s pressure-sensitive adhesives (PSA) are designed to meet the highest safety standards and reduce your total energy consumption for a wide range of applications.

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Paper Packaging

Consumer demand has changed the needs of paper packaging. Henkel’s water-based adhesives provide more sustainable options for on-the-go paper containers and packaging for flexible bonding and increased line speeds.

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Sports and Fashion

Rising labor and production costs are primary challenges in the sports and fashion industry. Henkel offers a large range of water-based adhesives combined with specific process know-how to support your manufacturing needs.

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Water-Based Adhesive Troubleshooting

Water-based adhesives can be used on a range of substrates including plastics, paper, cardboard, metallic films, and natural and synthetic textiles. They are cost-effective to produce and easy to use. In most cases, it is easier to maintain a uniform consistency with a wet bond adhesive. Water-based adhesives are safer for the environment than solvent-based adhesives.

Reducing or eliminating downtime is essential for all businesses. There can be many different reasons for line production downtime when using water-based adhesives. In response, Henkel has developed troubleshooting advice for the most common problems.

Slinging, Throwing or Splashing – a common challenge with water-based adhesives when the centrifugal force throws adhesive on equipment and surrounding areas. There are several causes for slinging:

  • Adhesive accumulation on the edge of rollers
  • Adhesive drying too fast
  • Adhesive level in the pot is higher than recommended

There are several simple solutions to reduce water-based adhesive slinging. The most common one is to check the adhesive viscosity and adjust the thickness. There are also equipment adjustments including cleaning or changing out the rollers; applying grease to the outside edges of the roller to contain the adhesive; and adjusting the roller speeds. Checking the amount of adhesive applied is another area which can impact slinging.

Uneven Coat Weights – occurs when there are variations on the application of the water-based adhesives. Some of the common causes are associated with uneven pressure between the applicators and the substrates. It can also occur when there is dried adhesive withing the system which impacts dispensing the adhesive.

Adjusting the applicator positions – either between rollers/applicators, the blanket or substrates. The applicator should just barely contact the substrate, also known as “kissing” the substrate. Another area to assess is the pressure and check for low areas between the applicator and substrate. Cleaning the rollers should be a common activity completed by operators to avoid remnant adhesive on the rollers/applicators which can impact the coat weight.

Voids and Skips in the Pattern – impact the adhesive application and are commonly caused by issues with the adhesive viscosity. Common culprits are:

  • Using mixed adhesive after end of pot life
  • Allowing a skin to form on the adhesive during downtime
  • Using improperly mixed adhesive or breaking the gel structure prior to application

To avoid these issues with water-based adhesives, it is important to assure thorough mixing occurs prior to starting the line and covering the adhesive during downtime. Checking the rollers to assure there is not any residue is also an option and should be completed by operators on a regular basis.

Tailing or Satelliting – describes when the peak of the dispensed water-based adhesive falls away from the center of the bead or pattern and creates a “tail” on the substrate. This is generally caused by too much adhesive being applied. 

The most common solution is to reduce the amount of water-based adhesive being dispensed or existing on the rollers. Operators should check the pump rate to assure it is not over pumping adhesive. Some general guidance on pumping, adhesive beads should be a pencil width, and pump strokes should be less than 30 strokes/minute. Also checking the water-based adhesive viscosity and adjust the thickness may be another method to correct. There are also equipment adjustments including cleaning or changing out the rollers.

Adhesive Temperature Fluctuations – it is important to keep water-based adhesives at the proper storage and processing temperatures to avoid issues. Whether too cold or too hot, temperature can significantly impact the performance. Water-based adhesive that is too cold exhibits poor flowability, increased viscosity, decreased set speed and less adhesive transfer. Water-based adhesive that is too hot has poor shelf stability and poor recirculation stability – both leading to increased waste.

There are many solutions manufacturers can employ to avoid issues related to temperature. First, water-based adhesives should be stored in a temperature-controlled environment 7-days prior to use and avoid storing on a cold floor. Second, tote, drum, or pail warmers are available to purchase from industrial supply stores and can mitigate issues related to temperature. When using water-based adhesives, it is recommended to warm the adhesive to at least 21°C (70°F) and use the adhesive before the “Best If Used By” date. Finally, placing an air hose into the top of the tote to create a pressure difference can also mitigate issues related to temperature.

For regions with common freeze seasons, it is important to be proactive in placing orders and checking water-based adhesive upon delivery. Henkel provides common tips during “Freeze Season” and works with customers to:

  • Avoid water-based adhesives in transit over the weekend when there is a greater risk of temperature impacts
  • Plan additional lead time to avoid impacts from carrier embargos due to inclement weather
  • Inspect all materials upon delivery to identify frozen materials immediately

For more information on troubleshooting water-based adhesives, contact Henkel’s technical customer service team to answer questions and assist with information on products and applications.

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