Overcoming Challenges in Rubber to Substrate Bonding | Adhesives manufacturing company

Overcoming Challenges in Rubber-to-Substrate Bonding

Posted 25 Sep 2024 by Rutika Swenson, Business Development Manager

Imagine a cross-country road trip in a full-size SUV through the American Southwest. You could travel hundreds of miles over potentially rough terrain, enduring temperatures over 100°F. Yet the SUV's 400-pound engine would remain cradled by rubber-coated mountings, keeping the vehicle in motion and its passengers safe.

The rubber is what protects the engine from shock and vibration. However, the real hero is the adhesive that bonds the rubber to the metal substrates beneath, ensuring the system holds together. Here, we'll cover adhesive solutions for bonding rubber, including:

• Where rubber is used and what it has to offer
• How to overcome the challenges of bonding rubber to other materials
• How the adhesives used in rubber-to-substrate bonding can transform other parts of your manufacturing process

Benefits of Rubber for Industrial Use

Rubber is used widely across many industries for its flexibility, capacity to absorb shock and withstand moisture, strength, durability, abrasion and chemical resistance, and low cost and weight. In its uncured form, rubber is highly elastic, meaning it can be stretched without breaking.

Rubber's unique properties complement the assets of other materials, such as the structural benefit of metal or the tear strength of fabric. For example, bonding rubber to a metal rod makes it more durable, and bonding rubber to cotton outwear keeps the clothes worn underneath dry.

Enhancing materials with rubber is essential for many components used in the power grid, transportation, oil, gas, and mining industries. For example, rubber bridge bearings absorb the shock of passing vehicles to maintain the bridge's structural integrity, rubber-coated electrical connectors prevent electric shocks, and tank liners coated with rubber keep water from seeping out. Bonding rubber to other substrates can improve their performance and resilience-critical qualities in parts made for industrial use.

Rubber can be used in bridge bearings to absorb the shock of passing vehicles.

Challenges in Rubber-to-Substrate Bonding

Rubber's unique mechanical properties provide distinct advantages in industrial use, but they also complicate the bonding process. Rubber has low wettability, meaning liquids do not spread out on its surface. The material also has different mechanical properties before and after curing. Commonly used adhesives, such as epoxy, acrylics, and polyurethane, may fail to adhere substances to rubber when they come under stress. These challenges underscore the need for effective solutions for rubber-to-substrate bonding.

CILBOND® Matches the Mechanical Properties of Rubber

Adhering rubber successfully to another substrate requires a bonding agent that can match its flexibility. In other words, the bonding agent must let rubber be rubber, even when attached to another material. This is where H.B. Fuller's CILBOND® bonding agents come into play. CILBOND® chemically bonds rubber during the molding and casting process and can take on the properties of rubber, such as withstanding extreme environmental factors and protecting parts from vibration and moisture.

Typically, adhesives are applied in a two-to-three-millimeter thickness during the bonding process. This relatively thick application can make it hard for the materials to establish covalent bonds. CILBOND®, in contrast, is applied in microns. Applying adhesives in this extremely thin layer helps establish a strong bond between the substrate surface and the rubber.

CILBOND® is used for rubber-to-substrate bonding of parts that experience high levels of wear and tear, including:

• Anti-vibration components
• Mining grates
• Oil and gas pump linings
• Bridge bearings
• Tank linings
• Rubber rollers
• Electrical connectors
• Power transmission belting

CILBOND® has many applications for rubber-to-substrate bonding.

How Rubber-to-Substrate Adhesives Benefit Manufacturers

In addition to providing a solution for the challenges of rubber-to-substrate bonding, CILBOND® offers manufacturers opportunities to improve operational efficiency and environmental sustainability.

Advantages of One-Coat Application

Rubber-to-substrate bonding agents are often applied in two coats. Two-coat applications include a primer, which prepares materials for bonding, and an adhesive, which bonds materials. Production must include time for the primer to dry before applying the adhesive.

One-coat applications have a unique chemical composition that removes the need for applying a primer. Surfaces will still need to be prepped through sanding or cleaning, but the production step of applying and drying the primer is no longer necessary. Removing this step reduces production time and diminishes the possibility of errors due to workers forgetting which coat they are on.

In addition to improving efficiency, one-coat adhesives use less material, meaning less material must be produced and purchased. The solvents typically used in rubber-to-substate adhesives give off volatile organic compounds (VOCs) that require expensive mitigation and safety measures. Reducing the amount of VOC material used in production can result in significant cost-savings and improved workplace safety.

Because two-coat bonding agents have been the norm for so many years and provide reliable results, manufacturers may hesitate to switch to one-coat agents. However, one-coat products can save costs and improve efficiency without compromising quality.

"A lot of companies are more familiar with the two-coat process, and some are more resistant to change. When customers learn how the one-coat process saves them time and money, however, they see the value and are willing to adopt it." - Rutika Swenson, Business Development Manager- CILBOND®, H.B. Fuller

Water-Based Adhesives Improve Environmental Sustainability

Another shake-up in the world of rubber-to-substate bonding is using water-based adhesives instead of solvent-based adhesives. The solvents used in solvent-based adhesives are highly flammable and often contain VOCs. Since many governments have regulations limiting the amount of VOCs a factory can produce, the cost of managing VOCs to fit requirements can be enormous. Switching from solvent to water mitigates VOC-management costs, eliminates the need to dispose of the hazardous waste produced by solvents, and increases workplace safety.

Although water-based adhesives are just as effective as solvent-based adhesives, they do require manufacturers to make small changes to their production processes. For example, water-based adhesives take longer to dry than solvents and must dry from the inside out. To achieve this, manufacturers must accommodate longer drying times and invest in ovens to pre-heat components to aid in the drying process.

The investment in additional equipment, however, is small compared to the cost savings of reducing VOC emissions. While ovens can cost tens of thousands of dollars, VOC management costs much, much more. For example, manufacturers commonly use regenerative thermal oxidizer (RTO) systems to remove pollutants from exhaust streams. The RTOs needed to remove VOC emissions in large facilities can cost over a million dollars.

H.B. Fuller's CILBOND® is a water-based adhesive. Our team can guide customers who are ready to switch from solvent-based to water-based adhesives and willing to make the necessary adjustments.

"There are a lot of ways we can work with a customer to make sure they are following the right procedures. We offer support to make sure their process is correct, and they are optimizing how they use the bonding agents." -Rutika Swenson, Business Development Manager-CILBOND®, H.B. Fuller

Partnering with H.B. Fuller to Solve Adhesive Challenges

H.B. Fuller has a history of producing products that meet challenging scenarios and provide practical benefits for the industries we serve. Our team of experts can help you adapt your process to get the most out of our products. Explore how CILBOND® one-coat bonding agents can solve rubber-to-substrate adhesion challenges, or contact an expert to see how CILBOND® can meet specific needs.

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