Epoxies vs Polyurethanes
Resin coatings are extremely useful in commercial and industrial settings and even in the art world. Resins are commonly used to coat surfaces like concrete floors or countertops, create high-gloss finishes, and make repairs. Two of the most common resins are epoxies and polyurethanes. Generally, epoxies are rigid, while polyurethanes will typically be more elastic. Both can be formulated to be extremely strong, pass biocompatibility testing, or have high resistance to UV light.
At Hapco Inc., we are a leading manufacturer and distributor of polyurethane and epoxy coatings, release agents, adhesives, and other liquid molding technologies. Since 1969, we have offered our clients quality formulations that are applicable in many industries.
What Are Epoxies
Epoxy plastics are typically created by mixing epoxy resins (Part A) with a matching catalyst (Part B) at various ratios. The mixture then cures to form a solid material. Additives are often used in resin coatings to improve durability, UV stability, adhesion properties, and other factors. Epoxies can come in the form of a single-component resin that cures by heat or UV light, and it can be formulated as a liquid resin, powder, or putty.
Epoxies have a wide range of applications, including:
- Electronics and Electrical Systems: Epoxy resins and powders are excellent insulators and offer protection from short circuits. Because of this, they are used in the manufacturing of generators, transformers, insulators, and motors.
- Coating and Sealant: Epoxies are commonly used in the manufacturing of ships, UAVs, military vehicles, and aircraft to protect surfaces, strengthen materials, and keep them from rust and deterioration. Due to the naturally thicker viscosity, epoxy resins can create very hard, durable finishes with adequate thickness after one or two coats.
- Repairs: Epoxy resins are often used to repair industrial manufacturing equipment due to their strong adhesive properties. Fragile objects like ceramic and glass, and stronger materials like metals, woods, and other synthetic materials, are frequently coated, repaired, or bonded using epoxy resins.
- Filter & Ultrafilter Manufacture
Advantages of Epoxies
Depending on the application, epoxies offer a range of benefits, including:
- Lower Cost: Epoxies are typically more affordable than polyurethane alternatives.
- Adhesion Properties: Epoxies can adhere to most substrates without a primer.
- Excellent Dielectric Properties: As an insulating material, epoxies can transmit electricity without acting as a conductor.
- Versatile: Depending on the resin and hardener used, epoxies can be rigid or flexible to suit the application requirements.
- Moisture Resistant: Epoxies are suitable for applications with high moisture exposure due to their high resistance to humidity and moisture.
- No VOCs: Epoxies don’t require a solvent for most applications, so they do not release harmful fumes into the air.
Disadvantages of Epoxies
- Higher Viscosity
- Yellowing: Epoxies will yellow over time when exposed to UV rays.
- Brittle: Rigid epoxies are prone to chipping and cracking if not properly maintained.
What are Polyurethanes
There are two types of polyurethanes: thermoset and thermoplastic. Hapco manufactures thermoset polyurethanes, which are formed by reacting a polyol with an isocyanate. The resulting polymer (Part A) is then cured with a catalyst (Part B). Once they’re set, they can’t be melted or softened. Thermoplastic polyurethanes, on the other hand, can be reheated and reprocessed multiple times without losing their properties. Polyurethanes have many desirable properties, including high tensile strength, natural UV stability, and abrasion resistance. They also have good thermal and chemical resistance and are generally non-toxic.
The possible applications for polyurethane resin include:
- Medical: Polyurethanes are used in many hospital applications because they are safe for individuals with latex allergies. They are used in beddings, gloves, wound dressing, and tubing.
- Insulation: Polyurethane foam is an energy-saving insulation option for cars, homes, and electronics. Polyurethane reduces external noise in buildings and vehicles and maintains a desirable temperature.
- Electronics: Polyurethane can be used to encapsulate, seal, and insulate different electronic components. They are also used to make microelectronic components and cables.
- Automotive: Polyurethane foams are used in cars to provide insulation and impact protection to keep passengers safe in the event of a crash. Polyurethane can also be used to create plastic interior parts such as console covers, door panels, and headliners because it’s soft and pliable.
- Packaging: Because polyurethanes can come in expanding foam form, you can use it for packaging items in different shapes. It also reduces the weight of the package.
Advantages of Polyurethanes
Many industries choose polyurethanes for their applications due to their range of benefits, which include:
- Hardness Range: Polyurethanes can be made flexible or rigid, and can fall anywhere between 20 SHORE A to 85 SHORE D on the hardness scale.
- UV Resistant: Polyurethanes are naturally resistant to ultraviolet rays and have much better color stability over time.
- Abrasion & Impact Resistant: Polyurethanes are suitable for applications in extreme environments because they resist surface damage and can withstand extreme force.
- Water, Oil, & Grease Resistant: Ideal for subsea applications, polyurethanes keep their structural integrity when exposed to water, oil, and grease.
- Thermal Shock Resistant: Thermoset polyurethanes are incredibly resilient to thermal shock and resist rapid and significant temperature drops without shattering.
- Low Odor
Disadvantages of Polyurethanes
- Higher Cost: Although polyurethane has a long lifespan, some businesses can’t afford the high upfront cost. You might have to opt for polyester or epoxy resins because they’re cheaper, although they won’t last as long as PU.
- Moisture Sensitive: While still in their liquid state, polyurethanes are susceptible to humidity and moisture, and will crystallize in the containers if too much moisture is present. When mixed, an excess of bubbles will appear or the resin may behave like an expanding foam.
- Shorter Lifespan: Flexible PUs, especially the lower durometers, will degrade over time. Being under stress will cause molecular bonds to break down much faster than rigid materials.
Epoxies and Polyurethanes at Hapco Inc.
Resins are tough, flexible, and versatile, making them the perfect choice for a wide range of applications. Hapco Inc. offers multiple polyurethane and epoxy products for different applications. With over 50 years of experience in this industry, we have the expertise and skills to produce the best resin materials in the market. We are an ISO 9001-certified company dedicated to meeting all our customers’ needs. Contact us today for more details about our materials or request a quote to get started.