Overview of Unsaturated Resin

Keywords:Unsaturated Resin  Unsaturated Polyester Resin  Unsaturated

Development History

The earliest resin discovered by humans was a fatty substance extracted from tree secretions, such as rosin, which is why it is called "fat"."Until 1906, when phenolic resin was first artificially synthesized, a new era of synthetic resins was opened. In 1942, the American Rubber Company first produced unsaturated polyester resin, and later any unprocessed polymer was referred to as resin. However, it has long been unrelated to "trees". Resins are divided into two main categories: thermoplastic resins and thermosetting resins. Thermoplastic resins are those that can be melted and solidified repeatedly upon heating and cooling, while thermosetting resins, such as phenolic resin, epoxy resin, and unsaturated polyester resin, become irreversible solids that do not dissolve or melt after curing.Epoxy Resin, unsaturated polyester resin, etc.

Introduction

"Polyester"is a type of polymer compound that contains ester bonds, distinguished from "phenolic" and "epoxy" resins. This polymer compound is generated from the polycondensation of dibasic acids and dibasic alcohols, and when this polymer compound contains unsaturated double bonds, it is called unsaturated polyester. This unsaturated polyester dissolves in monomers with polymerization capability (generally styrene), and when it becomes a viscous liquid, it is called unsaturated polyester resin (English name Unsaturated Polyester Resin, abbreviated as UPR). Therefore, unsaturated polyester resin can be defined as a viscous liquid formed by the polycondensation of dibasic acids and dibasic alcohols containing unsaturated dibasic acids or dibasic alcohols dissolved in monomers (usually styrene).Characteristics

Unsaturated polyester resin is a thermosetting resin that can cure into an insoluble and infusible polymer network under the influence of temperature or initiators. However, this polymer has very low mechanical strength and cannot meet the requirements of most applications. When reinforced with glass fiber, it can become a composite material, commonly known as "glass fiber reinforced plastic" (English name Fiber Reinforced Plastics, abbreviated as FRP).

 FRPhas greatly improved mechanical strength and performance compared to resin castings.The glass fiber reinforced plastic (UPR-FRP) has the following characteristics:

 Lightweight and high strengthUnsaturated ResinThe density of FRP is 1.4-2.2g/cm3,

1.which is 4-5 times lighter than steel, yet its strength is not small, with specific strength exceeding that of structural steel, hard aluminum, and fir. This is very important for products in aviation, aerospace, rockets, missiles, military equipment, and transportation that need to reduce weight. For example, the Boeing 747 jetliner uses 2.2 tons of FRP components in its main structure, effectively saving fuel, increasing speed, extending range, and increasing payload.

UPR-FRP is a good corrosion-resistant material, capable of withstanding general concentrations of acids, bases, salts, most organic solvents, seawater, atmosphere, oils, and has strong resistance to microorganisms. It is widely used in various fields of the national economy such as petroleum, chemical industry, pesticides, medicine, dyes, electroplating, electrolysis, smelting, and light industry, playing an irreplaceable role that other materials cannot.Excellent electrical performanceIt has excellent insulation properties and can maintain good dielectric performance under high frequency. It does not reflect radio waves, is not affected by electromagnetic forces, and has good microwave permeability, making it an ideal material for manufacturing radar covers. Using it to manufacture insulating components in instruments, motors, and electrical products can improve the service life and reliability of electrical appliances.Unique thermal performance UPR-FRP

2.has a thermal conductivity of 0.3-0.4Kcal/mh

UPR-FRP℃, which is only 1/100-1/1000 of that of metals, making it an excellent insulating material. Doors and windows made from it are a new type of energy-saving building material of the fifth generation. In addition, the thermal expansion coefficient of FRP is also very small, close to that of general metal materials, so FRP can be connected to metals without generating stress due to thermal expansion, which is beneficial for bonding with metal substrates or concrete structures.

Excellent processing performanceUPRhas excellent processing performance, with a simple process that allows for one-time molding, which can be formed at room temperature and pressure or cured with heat and pressure, and no low molecular by-products are generated during the curing process, allowing for the production of relatively uniform products. Due to its excellent processing performance, it has been widely used in recent years to make crafts, imitation marble products, polyester paints, and other non-glass fiber reinforced materials.

3.Good designability of materials

is a composite material with UPR as the matrix and glass fiber as the reinforcing aggregate, both of which are processed into the final shape in one step. Therefore, FRPis not just a material, but also a structure. The so-called designability includes two aspects: (1) Functional design; by selecting suitable UPR and glass fiber, FRP products with various special functions can be made, such as corrosion-resistant products, products that can withstand instantaneous high temperatures, light-transmitting sheets, fire-retardant products, and UV-resistant products. (2) Structural design: various product structures can be flexibly designed according to needs, such as glass fiber doors and windows, glass fiber gratings, glass fiber pipes, glass fiber troughs, and glass fiber tanks.

4No material is omnipotent, and FRP

UPR-FRPis no exception. First of all, FRP为基体，以玻璃纤维为增强骨材的复合材料，二者经过一次性加工成型为最终形状的制品。所以FRP不仅仅是一种材料，同时也是一种结构。所谓可设计性包含两方面内容：（1）功能设计；通过选择合适的UPR和玻璃纤维可以制成具有各种特殊功能的FRP制品，如：可以制成耐腐蚀的产品；可以制成耐瞬时高温的产品；可制成透光板材；可制成耐火阻燃制品；可制成耐紫外线制品.（2）结构设计：可以根据需要，灵活地设计出各种产品结构，如玻璃钢门窗、玻璃钢格栅、玻璃钢管、玻璃钢槽、玻璃钢罐等。

任何一种材料都不是万能的，FRP也不例外。首先FRPThere are many essential differences compared to metals, such as metals being isotropic materials while FRP is an anisotropic material. Under stress, metals generally undergo two stages: elastic deformation and plastic deformation, while FRP generally does not have a significant plastic deformation stage under stress, lacks a yield point, exhibits delamination during loading, and is prone to sudden fracture under overload. Secondly, FRP has a lower modulus, which is 10 times worse than steel, so any product with high rigidity requirements must be carefully designed. Thirdly, the heat resistance of FRP is far inferior to that of metal materials; so far, the long-term use temperature of FRP is still limited to below 200°C.

Types

As FRPSurface decorative anti-aging flame-retardant gel coats, heat-resistant gel coats, spray gel coats, mold gel coats, crack-free gel coats, radiation-cured gel coats, high wear-resistant gel coats, etc.

According to the structure of unsaturated polyester resin, it can be divided into ortho-type, meta-type, para-type, bisphenol A type, vinyl ester type, etc.;

According to their performance, they can be divided into general type, anti-corrosion type, self-extinguishing type, heat-resistant type, low shrinkage type, etc.;

According to their main uses, they can be divided into glass fiber reinforced plastic (FRP) and non-glass fiber reinforced resin.The so-calledglass fiber reinforced plasticproducts refer to various products made of resin reinforced withglass fiberand its products, also known as glass fiber reinforced plastic (abbreviated as FRP or glass fiber); non-glass fiber reinforced products are various products made by mixing resin with inorganic fillers or using them alone, also known as non-reinforced glass fiber products.

Uses

Classified by specific special varieties, including winding resin, injection resin, RTMresin, pultrusion resin, SMC, BMC resin, flame-retardant resin, food-grade resin, anti-corrosion resin, air-dry resin, polycarbonate resin, craft resin, button resin, agate resin, artificial stone resin, high transparency resin crystal resin, atomic gray resin, etc.