Resin typically refers to an organic polymer that softens or melts when heated and flows under external force. At room temperature, it is solid or semi-solid, and sometimes liquid. Broadly defined, any polymer compound that can be used as raw material for plastic products processing is called resin.
Classification of Resins
Resins can be classified into natural resins and synthetic resins based on their source. Natural resins are amorphous organic substances secreted by plants and animals, such as rosin and amber. With the development of chemical engineering, a series of synthetic polymers have been created, known as synthetic resins. These include five major types: polyethylene (PE), polypropylene (PP), polyvinyl chloride (PVC), polystyrene (PS), and ABS resin.
Based on different processing behaviors, resins can be divided into thermoplastic resins and thermosetting resins. Thermoplastic resins soften and solidify upon heating and cooling, such as unsaturated polyester, vinyl ester, epoxy, phenolic, and bismaleimide (BMI)/polyimide resins. Thermosetting resins, on the other hand, undergo chemical reactions when heated and do not melt after curing, such as polypropylene (PP), polycarbonate (PC), nylon (NYLON), polyether ether ketone (PEEK), and polyethersulfone (PES).
Overview of Common Resins and Their Properties
Acrylic Resin
Acrylic resins are polymers obtained by the homopolymerization or copolymerization of acrylic monomers, including both thermoplastic and thermosetting acrylic resins. They are light-colored, highly transparent, and possess the following excellent properties:
1. Good weather resistance, not easily affected by UV rays or oxidation, suitable for outdoor use.
2. Good chemical resistance, capable of resisting acids, bases, and solvents.
3. High transparency, advantageous for making transparent products.
4. Stable performance within a certain temperature range, not prone to deformation or melting.
5. Good processing performance, easy to shape and process, suitable for various processing techniques.
Currently, acrylic resins are widely used in coatings, printing inks, plastic products, adhesives, and packaging materials, gaining widespread popularity due to their excellent performance and versatility.
Polyurethane Resin
Polyurethane resins are high molecular compounds formed by the polymerization of polyols and polyisocyanates, offering many characteristics:
1. Good adhesion, high strength, and excellent wear resistance.
2. Excellent tensile and flexibility.
3. Good water and solvent resistance.
4. Wide curing temperature range, can cure under high and low-temperature conditions.
5. Superior high and low-temperature performance.
6. Good decorative and protective properties.
7. Excellent weather resistance with aliphatic polyisocyanates.
8. Relatively high cost.
9. Hydroxyl or carboxyl-containing polyurethane resins can be configured with isocyanate curing agents for two-component systems.
Due to these properties, polyurethane resins find extensive applications in aviation, railways, construction, sports, wooden furniture, metal surface coatings, storage tanks, pipelines, thermal insulation, pre-insulated polyurethane panels, plastic products, synthetic rubber products, synthetic fibers, adhesives, coatings, wood products, chemical equipment, telecommunications equipment, and various transportation tools' surface coatings.
Epoxy Resin
Epoxy resins refer to high molecular prepolymers containing two or more epoxy groups, a type of thermosetting resin typically formed by reacting epoxy compounds with compounds containing active hydrogen atoms (like phenols, amines). Their characteristics include:
1. Excellent adhesion, capable of bonding with metals, plastics, glass, fibers, and various materials.
2. High strength and hardness, along with good wear resistance.
3. Good color retention of the film.
4. Excellent chemical resistance, resisting acids, bases, and solvents.
5. Maintains good performance at high temperatures, suitable for high-temperature environments.
6. Excellent insulation and electrical properties, widely used in electronics.
7. Excellent water resistance after curing.
Because of these properties, epoxy resins are widely used in coatings, adhesives, composite materials, electronic encapsulation materials, flooring coatings, and anticorrosive coatings.
Polyester Resin
Polyester resins are polymer materials formed by esterification reactions, typically involving polycondensation reactions between diols and dibasic acids or anhydrides. Polyester resins can be divided into saturated polyester resins and unsaturated polyester resins. Key properties of polyester resins include:
1. High strength and hardness.
2. Excellent corrosion resistance to acids, bases, and solvents.
3. Maintains good performance within a certain temperature range, suitable for high-temperature applications.
4. Good insulation properties.
5. Some special formulations have good weather resistance, suitable for outdoor use.
6. Lighter than metals, advantageous in applications requiring lightweight materials.
7. Easy to mold and process, can be made into various shapes through injection molding, extrusion, calendering, etc.
However, polyester resins also have some drawbacks, such as high shrinkage rates, low adhesive toughness, and relatively poor chemical and water resistance. Therefore, polyester resins are primarily used for adhesives, especially for bonding fiberglass, hard plastics, concrete, and electrical encapsulation.
Alkyd Resin
Alkyd resins are a type of thermosetting resin made by esterification reactions between alcohols and anhydrides (or acids). These resins are commonly used in coatings, adhesives, encapsulation materials, and more, offering the following excellent properties:
1. Good corrosion resistance to acids, bases, and solvents.
2. Maintains good performance within a certain temperature range, suitable for high-temperature applications.
3. Typically high strength and hardness, useful for making wear-resistant coatings and materials.
Alkyd resins are mainly used in coatings, adhesives, composite materials, electronic encapsulation materials, flooring coatings, and anticorrosive coatings. In the coatings field, they are often used to make high-performance chemical-resistant coatings and high-temperature coatings; in adhesives, they are used to make high-strength structural adhesives; in electronic encapsulation materials, they are used to make high-performance encapsulation materials.
Natural Resin
Natural resins are a type of naturally occurring substance from plants or animals, typically renewable and biodegradable. These resins are commonly used in coatings, adhesives, fragrances, pharmaceuticals, and other fields. Key characteristics of natural resins include:
1. Natural resins are derived from plants or animals, renewable, and conducive to sustainable development.
2. Many natural resins are biodegradable and environmentally friendly.
3. The properties of natural resins vary based on the source, including viscosity, hardness, and heat resistance.
Natural resins are widely used in various fields due to their natural origin, renewability, and biodegradability, playing an important role, especially in environmental protection and sustainable development.
UV Resin
UV resins are curing-type resins that cure by exposure to ultraviolet light rather than heat or chemical reactions. UV resins feature fast curing, high hardness, high transparency, and good chemical resistance. Main properties of UV resins include:
1. Fast curing under UV light, high processing efficiency.
2. High hardness and wear resistance after curing, suitable for making high-strength products.
3. High transparency after curing, suitable for making transparent products or products requiring a high-gloss surface.
4. Good chemical resistance, able to resist acids, bases, and solvents.
UV resins, with their fast curing, high hardness, high transparency, and good chemical resistance, are commonly used in 3D printing, coatings and inks, printing, and optical materials.
Phenolic Resin
Phenolic resin, also known as Bakelite, is a synthetic plastic available as a colorless or yellow-brown transparent solid. Widely used in electrical equipment, it is well-known for its excellent properties:
1. Outstanding heat resistance, flame resistance, water resistance, and insulation.
2. Good acid resistance, electrical, and mechanical properties, easy to cut and process.
3. Phenolic resin can be divided into thermosetting and thermoplastic types. By adding different components during synthesis, various modified phenolic resins can be obtained with properties such as alkali resistance, wear resistance, oil resistance, and corrosion resistance.
4. Phenolic resin is also widely used as a tackifier in chloroprene adhesives and as a curing agent for butyl rubber.
Silicone Resin
Silicone resin is a cross-linked semi-inorganic polymer with a Si-O-Si main chain and organic groups attached, combining the properties of inorganic and organic materials. Specific properties include:
1. Excellent weather resistance, stable under UV light, not prone to yellowing.
2. Good water resistance and high-temperature performance, maintaining excellent properties at high temperatures.
3. Superior electrical insulation, stable dielectric properties under a wide range of environmental conditions (temperature, humidity, and frequency).
4. Moisture-proof, mildew-proof, radiation-resistant, and oxidation-resistant, effectively protecting coatings from environmental damage.
Based on its outstanding performance, silicone resin is widely used in coatings, adhesives, sealants, electronic materials, and more. When used alone, its coating hardness is relatively low, so it is often blended with acrylic resin, alkyd resin, polyurethane resin, or epoxy resin to enhance hardness and drying speed. Silicone resin excels in color retention and weather resistance, making it a key component in various anticorrosive coatings, insulating coatings, heat-resistant and weather-resistant coatings, and moisture-proof coatings. In recent years, silicone resin has found extensive applications in motor equipment insulation varnishes, heat-resistant and weather-resistant anticorrosive coatings, moisture-proof coatings, and radiation-proof coatings.
Polyketone Resin
Polyketone resin is a high-performance thermoplastic resin known for its excellent heat resistance, chemical resistance, and mechanical properties. As a high molecular compound, it is widely used in the production of high-performance engineering plastics and composites. Key properties of polyketone resin include:
1. Excellent heat resistance and high-temperature performance, capable of withstanding prolonged high-temperature environments.
2. Superior mechanical properties, including high strength, rigidity, and wear resistance.
3. Excellent chemical resistance, resistant to various chemicals, acids, and bases.
4. Outstanding electrical insulation and dielectric properties, making it suitable for electronic applications.
Given its superior performance, polyketone resin is extensively used in the production of high-performance engineering plastics, automotive parts, electronic components, and various industrial applications requiring high strength, durability, and chemical resistance.
Aldehyde and Ketone Resin
Aldehyde-ketone resin is an excellent thermosetting resin with excellent heat resistance, corrosion resistance and mechanical properties. This resin is used in a wide range of applications, including the preparation of high-temperature, corrosion-resistant coatings, adhesives and composites. Its specific characteristics are as follows:
1.Excellent heat resistance, able to maintain stable performance in high temperature environments, usually withstanding temperatures above 250°C.
2. Excellent corrosion resistance, able to resist the erosion of chemicals such as acids, alkalis, and solvents.
3. Excellent mechanical properties, including high strength, rigidity and wear resistance, suitable for making high-demand engineering parts.
4. Excellent high temperature aging resistance, with less performance degradation during long-term use.
Aldehyde-ketone resin has excellent heat resistance, corrosion resistance and mechanical properties. It is suitable for coatings, adhesives, composite materials and other fields. It is an important high-performance resin material.
Amino Resin
Amino resin is a general term for resins prepared by the polycondensation process of amino-containing compounds and formaldehyde. When this type of resin is used as a cross-linking agent, amino resin can significantly improve the key properties of the paint film such as gloss, color retention, hardness, chemical resistance, water resistance and weather resistance.
In recent years, amino resins have been widely used in industrial coatings such as automobiles, industrial and agricultural machinery, rigid furniture, household appliances, and metal precoating.
Fluorocarbon Resin
Fluorocarbon resin is a resin made from the polymerization of fluoroolefin or the copolymerization of fluoroolefin and other monomers. Due to the large bond energy of the C-F bond, it gives the coating excellent chemical stability. Has the following features:
1. It has excellent corrosion resistance and chemical resistance, as well as excellent weather resistance, and can withstand high-intensity ultraviolet radiation.
2. It has good thermal stability, electrical properties and flame retardant properties.
At present, fluorocarbon resin is mainly used in heavy-duty anti-corrosion fields, such as marine anti-corrosion, bridge anti-corrosion, construction, etc.
