In a post, Chemique Adhesives says understanding adhesive classification can assist users in selecting the right adhesives for their application. The chemical composition of an adhesive generally involves a primary component that undergoes a chemical reaction to form a cured adhesive; however, this can vary depending on its intended use and desired properties as well as adhesion to different substrates.
Additionally, adhesives are most often classified according to their adhesion method.
1. Reactive Adhesives
2. Non-Reactive Adhesives
Reactive Adhesives: Chemical Bonding for Stronger Bonds
This type of adhesive undergoes a chemical reaction to form a strong bond and often involves setting or curing, which can be triggered by pressure, heat, or exposure to UV light or moisture. The examples are:
• Epoxy: Formed by the chemical reaction of an epoxy polymer and a hardener, such as a polyamide
• SMP (Silyl-Modified Polymers): Cures by reacting with moisture, either from the environment or when added as a second component
• Polyurethane (PU): Formed by the chemical reaction of a diisocyanate and a polyol
Non-Reactive Adhesives: Physical Bonding without Chemical Reactions
This type of adhesive forms a bond mainly through physical means, such as mechanical interlocking. Also, it does not undergo a chemical reaction. The examples include:
• Pressure Sensitive Adhesive (PSA): Bonds upon contact without the need for heat or solvents
• Hot-melt: Thermoplastic material applied in a hot liquid state and solidifies upon cooling
To discuss the adhesive requirements, Chemique Adhesives can provide assistance in choosing the most suitable adhesives for the project.
Adhesive Carrier Types: Solvents, Water, and Heat
Additionally, adhesives can be classified based on the type of carrier they are contained in. Adhesives are not always applied as pure substances and often require a carrier to aid in application or to control the curing process.
What are the Main Types of Adhesive Carriers?
They are:
• Solvent-Based: Uses a solvent (other than water) as a carrier. The solvent reduces viscosity and aids in application. Some adhesives activate upon solvent evaporation, while others begin curing immediately, regardless of the solvent’s presence
• Water-Based: Uses water as a carrier and often the adhesive is present as an emulsion. The water is removed through evaporation, absorption or by breaking down the emulsion
• Hot Melt: A type of 100% solids adhesive, where heat acts as the carrier. Applied hot, the heat reduces viscosity for ease of application. Upon cooling, they solidify forming a strong bond
• 100% Solids: Does not contain a carrier and can be applied directly to the surface. They cure without the need to remove any carrier material
Chemique Adhesives manufactures a variety of adhesives to suit a range of applications.
Adhesive Bonding Mechanisms: How Adhesives Form Strong Bonds?
Adhesive bonding is a process where two or more materials are joined together using an adhesive substance. The type of bond formed depends on the chemical properties of the adhesive and the surfaces to which it is applied.
Examples of Adhesive Bonding Mechanisms
• Non-pressure Sensitive Adhesive: Requires a wet or tacky state for bonding
• Pressure Sensitive Adhesive (PSA): Tacky and bonds upon pressure application
• Contact Adhesive: Applied to both surfaces, partially dried, and then bonded
What are the Popular Adhesive Types and Their Uses?
When selecting the right adhesive for a specific application, it’s important to consider the properties and characteristics of various types of adhesives. Below are some of the most popular adhesive types and their common uses:
• Epoxy Adhesive: Two-part adhesive known for its high strength and durability
• Pressure-Sensitive Adhesive (PSA): Self-adhesive material that bonds upon contact
• Polyvinyl Acetate Adhesive (PVA): Water-based adhesive commonly used for woodworking
• Contact Adhesive: Requires both surfaces to be coated before bonding
• Acrylic Adhesive: Versatile adhesive for various applications, including bonding plastics and metals
• Synthetic Rubber Based (SBR): Flexible adhesive often used for sealing and bonding
• Cyanoacrylate Adhesive: Known for its rapid curing time and strong bond strength
• MS / Hybrid Adhesives: Combination of polymers offering flexibility, adhesion, and durability
• Hot Melt Adhesive: Thermoplastic adhesive requiring heat to activate
• Water-Based Adhesive: Easy to apply adhesive, popular in the foam and furniture market
• Polyurethane Adhesive: Durable adhesive suitable for a variety of substrates
Key Factors in Adhesive Selection
When selecting an adhesive, there are a range of factors that should be taken into consideration, including the required bond strength, materials to be bonded, environmental conditions, and the application method. The number of components required for the most effective application is a crucial factor when assessing adhesive classification ad types. The majority of adhesives are either one-part (1K) or two-part (2K) systems, while more complex formulations may include multiple components that are blended before use.
