What are the differences between epoxy, MMA and polyurethane coatings?

Short answer: epoxy is the versatile all-rounder; MMA cures in about an hour, even below freezing; polyurethane is flexible and UV-stable, and polyurethane cement takes hot washdown in food plants. Choose by downtime, temperature and what the floor has to resist.

Here is a breakdown of the curing properties, applications and characteristics of each concrete protection system, to help you make better informed decisions when choosing your next coating solution.

Epoxy

According to Bernard Bauer, Operations Manager at Hychem, epoxy resins are one of the most versatile concrete coating solutions that can be used in multiple applications across a wide range of industries including concrete flooring, water, mining and wastewater industries. “Epoxy resins can be applied in a range of thicknesses for a multitude of applications including general flooring for commercial and industrial applications, decorative flooring, trowel-applied applications for heavy duty environments, spray-on linings and protective coatings as well as grouts for machinery bedding. “At Hychem we manufacture a range of epoxies with different characteristics and capabilities to suit almost every application, tailoring our products to meet the specific demands of our Australian conditions,” said Mr Bauer. Applications:

• Industrial and commercial flooring
• Concrete sealant for carparks
• Secondary containment protection
• Grouting applications
• Coatings for concrete wastewater pipes and tanks

Key characteristics:

• Strong adhesion to the substrate
• High mechanical properties
• Corrosion resistance
• Resistance to chemicals
• Can have antimicrobial properties
• Abrasion resistance
• Range of colours and textures available
• Low VOC

Strength: Compressive strengths of >120Mpa Thickness of application: 100 microns to >6mm UV stability: Good UV stability although generally not as good as some PU and PMMA, however Hychem Glaze 3 or SF20UV have increased UV stability. Cure time: 8 hrs at 25℃ for dry touch. 24hrs before it can be walked on. Temperature resistance: 60℃ +. Chemical Structure The majority of epoxy products are based on a reaction between diglycidyl ether of bisphenol A (DGEBA – epoxy resin) and an amine hardener. These components react to give a film forming a crosslinked polymer. Novolac epoxy resins for high temperatures Novolac is another class of epoxy resin that has higher functionality than standard DGEBA resulting in a higher crosslink density. Novolac epoxies provide an increase in chemical resistance by about 30 per cent over regular epoxies, as well as a significant increase in resistance to sulfuric acid and heat. Choosing the curing agent The curing agent plays a major role in determining the properties of the final cured epoxy. These properties include cure speed, gloss level, chemical resistance, strength and UV resistance. “A hardener used in an epoxy for topcoats is likely different from that used for machinery grouting. “An epoxy topcoat needs to produce a high quality finish where properties such as compressive strength are not as important in a thin film.

Conversely, compressive strength and other properties such as creep and heat release are very important in a machinery grout and the amine hardener plays a big part in this.

Chris BauerHychem Flooring

Methyl Methacrylate (MMA)

Methyl Methacrylate systems(MMA) are designed for use where fast curing is required and/or where low application temperatures exist. These systems can be put into service for traffic after as little as a few hours which is generally not possible with epoxy and polyurethane flooring systems. “The main advantage of MMA flooring systems is their very fast cure time and the ability to be applied below zero degrees. Another feature is their excellent weather resistance. “MMA can be formulated to produce a highly flexible waterproofing solution with the advantage of having excellent crack-bridging characteristics while also being trafficable. “This highly flexible MMA is a European-manufactured system, solving the problem of outside carpark waterproofing that requires both increased flex as well as high durability to withstand the impact of regular car traffic.” Application:

• Fast turnaround flooring
• Traffic marking
• Anti-slip pedestrian walkways
• Crack-bridging applications in high traffic areas

Key characteristics:

• Extremely fast curing
• Can have anti-microbial qualities
• Strong odour which can be mitigated with correct ventilation at the application site
• Varying degrees of slip resistance can be attained
• Range of colours available
• High flex capability
• Crack-bridging capability
• Trafficable membranes
• High durability

Tensile Strength: 8Mpa Thickness of application: 500 microns to 6mm full trowel application. UV stability: High UV stability making them perfect for outdoor applications such as car parks, walkways and traffic markings. Cure time: 40 minutes to 1 hour Temperature resistance: 70℃ Chemical Structure MMA is a fairly simple molecule and is often formulated with other methacrylates such as 2-ethylhexyl methacrylate and 2-hydroxyethyl methacrylate. Curing Polymerisation is initiated by an organic peroxide.

Polyurethane

Polyurethane coatings produced by Hychem are varied, consisting of water-based, solvent based, 100 percent solids and cementitious products. Within this group of products we have properties including excellent UV and weather resistance, abrasion resistance, high heat and chemical resistance and also flexible products used as membrane systems for both foot and vehicular traffic. Applications:

• Antimicrobial flooring in harsh, heavy duty environments
• Chemical bunds
• Roads and bridges
• Balconies and patios
• Crack-bridging
• Carpark waterproofing

Key characteristics:

• Odourless
• Fast cure
• Trafficable
• Hygienic and safe surface finish
• Thermal shock resistant
• Chemically resistant to acetic acid, lactic acid and oleic acid from vegetable and animal fats
• High versatility in adhesion to different surfaces
• High abrasion resistance
• High resistance to corrosion
• High flexibility
• Low curing temperature capability
• Strong adhesion to the substrate
• Unlimited film build

Chemical Structure Polyurethane coatings from Hychem are either one-pack moisture cured or two pack systems based on a polyol and an isocyanate.