Epoxy resins are synthesized resins that have numerous industrial applications. They offer better chemical, mechanical and thermal properties than other types of resins. These are incredibly versatile and highly adhesive materials that are commonly used in manufacturing, woodworking and in construction industries.
Epoxy resin has excellent adhesive strength, it is resistant to moisture and chemicals, and can bear moderate temperatures. These and other incredible properties make epoxy resins the top choice for use in the construction industry worldwide. Epoxy resins are used as a strong waterproof barrier which is equally resistant to high temperatures. There are numerous other benefits of epoxy resins.
Still, safety precautions should be followed for proper handling as some formulations of epoxy resins are potentially hazardous and can cause significant damage to human health. According to a market research report by Mordor Intelligence, the epoxy resins market size in India was around USD 510 million in 2022. The report expects the market size to grow to around USD 930 million by 2032.
In this blog, we will learn everything there is to know about them, including the types, uses, properties and chemical composition of epoxy resins.
Epoxy Resin – What Is It?
Epoxy resin, by definition, is a two-part synthetic polymer material. Ideally, it is recommended to mix the two parts in a 4:1 or 2:1 resin-to-hardener ratio. When the two parts are mixed with each other they start a chemical reaction which produces a strong and durable adhesive solution.
Epoxy resins are highly adhesive and used in a wide variety of applications and industries. They can be used commercially or domestically. They are available in different brittleness and varying grades. These resins are tough, have strong adhesion properties and are also resistant to chemicals. Mostly, epoxy resins are used in construction and manufacturing, such as in making electric circuit boards and fiber optics.
Leading manufacturers Sakshi Chem Sciences offer a high-quality resin-based curing compound, called Addage BONDCOTE CCARB (Aluminum Resin Based.
Epoxy Resins – What Are They Made Of?
Epoxy resins are usually classified into two major categories – glycidyl and non-glycidyl. Glycidyl resins are further sub-classified into glycidyl-esters, glycidyl-ethers, or glycidyl-amines. Aliphatic and cyclo-aliphatic resins are classified as non-glycidyl resins. The most used solid epoxy resins in the construction industry are glycidyl-ether epoxies.
Below are some popular types of epoxy resins used in construction and manufacturing –
Aliphatic Epoxy Resins
Aliphatic epoxy resins are produced through two different methods. They can be made through a double bond epoxidation process which requires using cycloaliphatic epoxides and epoxidized vegetable oils. Solid epoxy resins can be produced through a reaction with epichlorohydrin, such as glycidyl esters and ethers.
Cycloaliphatic epoxides contain at least a single aliphatic ring inside the molecule that has the oxirane ring. These types of epoxy resins have a higher oxirane content, do not have chlorine but have a well-defined aliphatic structure. Thanks to these components, such epoxy resins have low dielectric constants, high Tg, low viscosity and are resistant to the effects of harsh weather conditions. These properties of epoxy resin make it an incredibly versatile material.
Bisphenol Epoxy Resin
Bisphenol-A diglycidyl ether (DGEBA) is one of the most widely used epoxy resins in the construction industry globally. It is created when bisphenol-A in a basic catalyst is mixed with epichlorohydrin and starts a chemical reaction. This epoxy resin type has the lowest molecular weight of all other resins.
Novolac Epoxy Resin
Novolac epoxy resins are made by the reaction between methanol (formaldehyde) and phenol. The reaction between Novolac and epichlorohydrin causes the creation of novolacs with glycidyl residues, such as Epoxyphenol Novolac (EPN) and Epoxycresol Novolac (ECN).
These epoxies do not contain volatile organic compounds (VOCs) or solvents, which makes them significantly safer to use and does not require workers to wear respirators when handling. They also have a higher adhesive strength, which makes them effective for optimal coverage, while ensuring durability and protection during the application process.
Halogenated Epoxy Resin
Halogenated epoxy resins are admixed to achieve special properties. This includes applying and mixing brominated and fluorinated varieties. The most common option is using brominated bisphenol A for electric applications and flame resistance.
However, the associated high cost and low Tg result in lower commercial production and limits the use of halogenated epoxy resins in the construction industry.
Glycidylamine Epoxy Resin
Glycidylamine epoxy resins are created when there is a contact reaction between aromatic amines and epichlorohydrin. These types of epoxy resins have a higher functionality level. High-grade Glycidylamine epoxy resins are easier to process as they have low to medium viscosity at room temperature.
Epoxy Resin Diluent
Epoxy resin diluents are created by glycidylation of aliphatic alcohols or polyols. The resultant compound can be mono-functional (such as dodecanol glycidyl ether), di-functional (such as butanediol diglycidyl ether), or high-functioning (such as trimethylolpropane triglycidyl ether).
Epoxy Resins – Safe Handling Tips
Though epoxy resins are manufactured to be as harmless as possible, there are still several safety precautions you need to follow.
It is highly recommended to protect your hands against exposure to resin and hardening liquids by wearing safety gloves. Nitrile gloves are suitable as they do not react when encountering resins or with your skin. You can use baby wipes to remove any resin from your skin. The remaining resin can be removed using soap and water. Apart from this, exfoliants can also be used to remove resins from the skin.
Wearing a plastic apron is another easy way to protect your skin from resins and to protect it from any spilled resins. If, despite wearing safety goggles, resin accidentally gets into the eyes, then you need to flush your eyes with water repeatedly for 15 minutes. However, you should avoid rubbing your eyes while washing. It is strongly advised to seek medical attention as soon as possible.
Apart from this, it is important to ensure adequate ventilation in the area when working with epoxy resins. You should keep windows and doors open, and switch on the ceiling fan or exhaust fan to get rid of the fumes. Besides this, it is recommended to wear a respirator as a safety precaution when handling epoxy resins.
Epoxy Resin – Processing And Curing Time
Epoxy resin needs to be cured and processed properly for it to achieve the desired heat resistance, as well as mechanical and chemical properties. Thankfully, you can easily produce the required properties in the epoxy resins by curing, which involves mixing an appropriate curative to achieve cross-linked thermoset structures. This process is essential to cultivating the required properties of epoxy resin.
Curing time often varies for different types of epoxy putties and pastes. Generally, it is recommended to cure epoxy resin with a warm, slow and long process. For instance, experts advise allowing epoxy resin to cure for up to 72 hours to ensure a strong adhesive bond. For applications with significant stress or high pressure, it is recommended to allow the epoxy resin to cure for as long as possible. This is possibly one of the few disadvantages of epoxy resin.
Curing epoxy resins usually involves two separate processes. Firstly, it can be cured by reacting with itself, called homopolymerisation, or by forming a copolymer with polyfunctional curatives or hardeners. Common epoxy resin hardeners include amines, acids, acid anhydrides, phenols, thiols and alcohols. Epoxy resin reacts the least with phenol and most with thiol. You can quicken the speed of the curing reaction by adding small quantities of accelerators, such as alcohols, carboxylic acids and tertiary amines.
Epoxy Resin – Mixing With Hardener
It is crucial to prepare epoxy resins properly to ensure an optimal and strong curing process. Below is a step-by-step guide on how to mix epoxy hardener and resin –
1 – Read instructions
The first step for properly curing epoxy resin requires carefully reading and completely understanding the instructions provided by the product manufacturer for the specific epoxy resin and hardener. The instructions for handling and processing epoxy resin and hardeners vary, including their storage and mixing ratios.
2 – Preparing process
The second step requires preparing a workplace for safely making the required epoxy resin mix. It is recommended to work in a well-ventilated area and wear a respirator as well as other protective gear, including goggles and gloves. Make sure to cover the surface with wax paper, plastic or similar protective material, to prevent damage from accidental spills.
3 – Measuring tips
Make sure to use clean measuring containers and choose different ones for resin and hardener. Usually, epoxy resins are mixed in a specific ratio with hardener, mostly measured in weight or volume. It is advised to measure resin and hardener by weight and volume, as per the instructions offered by the manufacturer. It is important to ensure accuracy and precision during measurement for optimal curing.
4 – Mixing properly
Use a clean container to pour in the measured amounts of epoxy resin and hardener. Use a mixing paddle or stirring stick designed specifically for mixing resin. Make sure to stir slowly, while scraping the bottom and sides of the container to completely mix the compound. You should gradually increase the stirring speed till the epoxy resin and hardener are completely combined.
5 – Using product
Epoxy resin has a limited life when mixed with hardeners, and it varies according to the specific product. As soon as the two components are mixed completely you should use the epoxy resin within the recommended timeframe to ensure optimal curing and adhesion.
Epoxy Resin – Uses
Epoxy resin is used for a variety of purposes, such as adhesion, coating and forming composite materials, including fiberglass reinforcements and carbon fiber. You can effectively modify the properties of epoxy resin. For example, silver-laced epoxies have higher electrical conductivity than others. There are also several different epoxy resin products available on the market today.
Let’s look at some more uses of epoxy resins in its different forms –
Adhesives
Epoxy resins are used as engineering adhesives or structural adhesives. They are available in chemical varieties, including cyanoacrylate, acrylic, and polyurethane. Epoxy adhesives are commonly used to bond snowboards, golf clubs, skis, and aircraft parts. These adhesives also provide excellent bonding to different materials, including stone, glass, metal, wood and other materials. However, epoxy adhesives tend to lose their adhesion powers when the ambient temperature rises above 177 degrees Celsius (350 degrees Fahrenheit).
Industrial
Epoxy resin products are also widely used as strong adhesives to produce industrial tools, including fixtures, castings, laminates, master models and molds. Today, plastic tooling is becoming increasingly popular as compared to wood and metal. It has higher efficiency and reduces expense, besides providing workability for a wide variety of industrial uses. Epoxy resin water resistance makes it an incredible component in many industrial applications.
Electrical
Epoxy resin is also widely used in the electrical industry. It is used to make printed wiring boards (PWBs), insulators, transformers, generators, and even motors. These resins have a higher level of electrical insulation and protect electrical components from short-circuiting caused by accumulation of moisture and dust.
Construction
Epoxy resin uses in construction are varied due to its exceptional durability, resistance to moisture and chemicals, and strong adhesive properties. Resin is used for repairing concrete structures, such as restoring a building’s integrity and filling cracks in floors, walls, and other surfaces. Besides, epoxy resin is widely used for durable and seamless flooring in industrial and commercial structures. Epoxy resin water resistance is also well-known and sought after in the construction business.
The reason for multiple epoxy resin uses in construction is that it gives a smooth surface that is resistant to impacts, abrasion and chemicals. Apart from this, epoxy resin is also used in construction for grouting applications and bonding agents where strong adhesion is needed.
Epoxy Resin – Comparison With Other Resins
Now that we’ve seen the numerous types, advantages and uses of resin, its time to check out the comparison between epoxy resin and others.
Casting Resin
Casting resin is a type of epoxy resin which is manufactured specifically for molding and casting applications. It has low viscosity, making it more fluid and takes longer to cure. This allows the resin to flow easily and fill the mold completely, thus effortlessly taking on even the finest shapes.
Casting epoxy resin is mostly used in manufacturing decorative objects, art pieces, and jewelry.
Acrylic Resin
Polymethyl methacrylate (PMMA) is also called Acrylic Resin. It is a thermoplastic material and mostly used as liquid monomer. It polymerizes when exposed to light or heat.
Acrylic resin has higher UV stability, impact resistance, and is clear which is why it is heavily used in making decorative items, orthopedic devices and dental prosthetics.
Polyester Resin
Polyester resin is a thermosetting polymer which cures when it is mixed with a hardener or catalyst. It has good mechanical strength and excellent chemical resistance. This makes polyester resin a common component in fiberglass reinforcement applications, such as building composite structures, automotive parts, and boats.
Conclusion
Epoxy resin is a synthesized resin with numerous industrial and construction applications. This type of resin has excellent mechanical, chemical and thermal properties as compared to other resins. The epoxy resins market size is also expected to grow at 7.00% CAGR by 2032, according to reports. There are almost no known disadvantages of epoxy resin as
Epoxy resins are applied in the liquid form, using sprays or rollers, or poured into molds. It becomes incredibly strong and durable after curing. These and similar other reasons make epoxy resins the top choice for various uses during building construction processes. Always buy epoxy resins from a renowned manufacturer, such as Sakshi Chem Sciences, to ensure the most satisfactory results.