There are two main types of resins: natural and synthetic. Both types of resins have a rich history. And while we focus on Polymer Resins here, we do feel it’s important to educate across both types so that we all better grasp the concepts from a general perspective.
Let’s begin with a little history lesson.
What Are Resins?
Resins are complex organic substances that are composed mainly of lighuids or solids that we derive from plants and often utilize in labs. They are made up from a network of molecules known as polymers. Lets break down both natural and synthetic resins.
Natural resins are, as one might expect, secreted by plants and most often, trees. Often, these resins are utilized by the tree to save itself from injury. When a tree experiences a wound, it releases resin to seal the wound and protect it against insects or fungus which might invade and eventually destroy the tree.
Over time, resins harden into substances such as amber. A natural resin is often sticky and viscous and typically hardens as it is exposed to air. There are many natural resins, here’s a few to consider:
Types of Resins
Rosin: Usually found in pine trees, its used to make adhesives, varnishes, and sticky grips for sports.
Amber: We’ve spoken to amber already in this article and it serves as our feature image, its typically found in ancient trees and leveraged to make jewelry.
Frankincense and Myrrh: Comes from tree sap and is often used in perfumes and incense.
Copal: A resin used in the production of varnishes and incense, so we might consider it a variable use.
Now let’s move to synthetic resins.
Synthetic resins are, as you likely understand, man-made. They are produced through chemical reactions known as polymerization.
These resins are engineered to have specific properties suited for a myriad of industrial applications from creating plastic to painting to adhesives and even electronics. Our guide to polymer resins discusses many of these use cases.
Let’s go over a few synthetic resins:
Epoxy Resin: A super strong adhesive that’s resistant to both heat and chemical exposure. Not difficult to see why it can be a great option for coating and adhesive production.
Polyester Resin: Used in fiberglass, auto parts, and marine hulls. Check out our polymer resins EV automobile blog for some cool information.
Polyurethane Resin: Uniquely flexible and resistant to abrasions makes it perfect for coatings, footwear, and foam.
Acrylic Resin: Utilized in paint formulations, coatings, and acrylic glass.
Both types of resins play a crucial role in their areas. Natural resins continue to be valued for many traditional and aesthetic uses while synthetic resins help evolve manufacturing due to their tailored properties and varied functionalities.
Historical Uses of Natural Resins
Natural resin use cases are found throughout history, including as far back as ancient civilizations.
In Egypt, resins like myrrh and frankincense were used extensively in religious ceremonies as incense and during the mummification process. Myrhh was well understood by ancient Egyptians to have amazing preservative and aromatic functions.
In Greece and Rome, resins were notably used as adhesives and as a waterproofing solution for ships. Greeks also appreciated the use of natural resins in jewelry making.
Some resins were integral in the formulation of inks used in historic manuscripts throughout history.
The Chinese use frankincense to treat arthritis, heal wounds, and reduce inflammation.
Historical Uses of Synthetic Resins
Synthetic resin use cases began to prosper in the early 20th century with phenolic resins which were invented by Leo Baekeland in 1907. This also marked the beginning stages of the plastic industry and led to the use of synthetic resins in a great many applications.
During both World Wars, the demand for materials like rubber led to impactful advancements in synthetic resins, particularly for building aircrafts, vehicles, and clothing.
Following the war, synthetic resin use helped companies manufacture a wide array of household items, especially for the electronic industry. Later on, synthetic resins would help the medical industry, as well.
Process and Manufacturing
Let’s examine how both synthetic and natural resins are collected, produced, and processed.
Natural Resins
As we mentioned earlier, natural resins are typically collected from trees. At a high level, an incision is made into the tree and the resin leaks out.
Once collected, natural resins may undergo various processing which depends on their ultimate use.
Cleaning and Purification: Resins such as frankincense are cleaned of bark and leaf matter and may be graded on color and overall quality.
Distillation: Products like turpentine are derived from the distillation of the pine resin.
Synthetic Resins
As you might imagine, manufacturing synthetic resins involves a more complex chemical process approach. This process is primarily known as polymerization. There’s several ways to achieve this.
Step 1, Monomer Production: The first step in resin production is the creation of monomers which serve as the basic building blocks of polymers. Typically, these monomers are derived from petroleum products, natural gases, and plant-based materials.
Step 2, Polymerization: Monomers now undergo polymerization, where they chemically react with the end goal of formation. The reaction is typically caused by heat, light, or other catalysts.
Step 3, Modifications and Additives: To enhance performance, durability and ease of processing, additives are mixed into the synthetic resins. This could be stabilizers which help prevent degradation or plasticizers that help make them more pliable or fillers that help make them heat resistant. There are numerous additive types that can be used for various purposes depending ultimately on the synthetic resins’ use case.
Step 4, Forming and Curing: At this stage, synthetic resins are now molded into specific shapes that get them closer to what they’ll be used for. There are numerous techniques used including injection molding, blow molding, and thermoforming.
Step 5, Quality Control: Ultimately, synthetic resins must be tested to ensure they meet standards and safety.
Applications of Resins
We frequently discuss the applications of resins on our blog.
Just to name a few, we have Outdoor applications, construction uses, and electronics manufacturing.
In construction, we find use cases for adhesives and sealants. Synthetic resins like epoxy and polyurethane are vital in these cases. Some resin-based foams are utilized for acoustic insulation in buildings.
Epoxy and silicone resins are widely used for encapsulating and insulating electronic components, protecting them from moisture, dust, and mechanical damage.
Polyurethane and polyester resins are used in consumer goods packaging for their robustness and flexibility. They can be found in everything from flexible pouches to rigid containers.
Amber and copal are popular in jewelry making.
The list of resin applications and use cases feels almost too infinite to list them all.
Resins are all around us. Natural and synthetic resins encourage safer, more functional, longer lasting goods and products and structures.