Get ready to meet polyimide (PI), a material so extraordinary, it’s quietly revolutionizing the world around us! From your smartphone to spacecraft, polyimide’s incredible properties are powering innovation across countless industries. Let’s explore this amazing material and uncover its secrets!
Polyimide: A Material with Superpowers:
Polyimide isn’t just any polymer; it’s a high-performance superhero with a remarkable combination of properties:
- Unbeatable Heat Resistance: Withstands incredibly high temperatures without losing its strength or shape—a game-changer for high-temperature applications.
- Super Strength and Flexibility: Boasts exceptional mechanical properties, offering both strength and flexibility, making it ideal for demanding environments.
- Chemical Fortress: Highly resistant to chemicals and solvents, maintaining its integrity even under harsh conditions.
- Perfect Insulator: Provides excellent electrical insulation, protecting sensitive components from damage.
Polyimide’s Amazing Applications:
Polyimide’s incredible properties have made it indispensable across various industries:
- Electronics Powerhouse: Found in flexible printed circuits, chip packaging, and high-temperature components, making our tech faster, smaller, and more durable.
- Aerospace Essential: Used in aircraft and spacecraft components, where its high-temperature resistance and strength are crucial for safety and performance.
- Automotive Innovation: Enhancing automotive parts with superior heat resistance and durability.
- New Energy Champion: Playing a vital role in batteries and other energy storage solutions, improving efficiency and safety.
A History of Innovation:
Polyimide’s journey is one of continuous innovation. From its early development as a high-performance engineering plastic to its current use in cutting-edge technologies, polyimide has consistently pushed the boundaries of what’s possible. The industry continues to refine its properties, exploring new applications and pushing the limits of performance.
The Quest for Transparency: Transparent Polyimide Film (CPI):
One of the most exciting frontiers in polyimide research is the development of transparent polyimide film (CPI). This material promises to revolutionize displays, offering superior flexibility, heat resistance, and clarity. Scientists are working tirelessly to overcome challenges related to color and transparency, paving the way for even more groundbreaking applications.
The Future is Polyimide:
Polyimide’s remarkable properties and diverse applications make it a cornerstone of modern technology. As research continues, we can expect even more innovative uses for this extraordinary material, shaping the future of electronics, aerospace, and countless other industries. Share this article and spread the word about polyimide—the unsung hero of modern technology!
Polyimide (PI) is a general term for a type of polymer containing imide rings in the main chain. It is mainly divided into three categories: thermoplastic polyimide, thermoset polyimide and modified polyimide. .
Among them, thermoplastic polyimides include homobenzene type, biphenyl type, ether anhydride type, ketone anhydride type, and fluoroanhydride type polyimide. Thermoset polyimides include norbornene dianhydride end-capped polyimide, ethynyl end-capped polyimide and bismaleimide. Modified polyimides mainly include polyetherimide, polyesterimide and polyamideimide.
Characteristics and applications of polyimide
1. Features
Polyimide is a high-performance polymer that has the following characteristics due to its unique chemical structure (including rigid aromatic rings and imide bonds):
1. High temperature resistance
-The long-term use temperature can reach -200~300°C, and can withstand high temperatures above 500°C in the short term.
-The decomposition temperature is high (usually >500°C), and the stability remains stable at high temperatures.
2. Excellent mechanical properties
-High tensile strength (typically 100–400MPa) and modulus, strong creep resistance.
-Low coefficient of thermal expansion (close to metal), suitable for precision devices.
3. Chemical stability
– Resistant to organic solvents, acids, radiation and ultraviolet rays, but may degrade in strong alkalis or high-temperature water vapor.
4. Insulation performance
-Low dielectric constant (3.0–3.5) and dielectric loss (0.004~0.007), suitable for high-frequency electronic devices.
-High breakdown voltage, used as insulating film or coating.
5. Resistant to radiation
– It has high radiation resistance, and its film’s strength can still maintain 86% when the absorbing dose reaches 5x107Gy. Its strength retention rate is still 90% after 1x108Gy electron irradiation.
6. Lightweight and flexibility
– Low density (1.3–1.6 g/cm³) and can be made into ultra-thin films (such as 10–25μm flexible circuit substrates).
7. Other features
-Abrasion resistance, flame retardant (limit oxygen index >36), some types are biocompatible.
2. Application areas
Polyimide is widely used in extreme or high-precision environments with its comprehensive performance:
1. Electronics and Semiconductors
-Flexible printed circuit (FPC): such as the base material of the folding screen of a mobile phone (such as the Samsung Galaxy Z series uses PI film).
-Chip package: Insulating layer or buffer material for wafer-level package.
-Insulating film: such as DuPont Kapton® films are used for high temperature resistant cables.
2.Aerospace
-Engine components: turbine blade coating, high temperature seal.
-Spacecraft materials: Mars rover thermal insulation layer, satellite solar sail film.
3. Automobile industry
-High temperature components: turbocharged hose, sensor housing.
-Lightweight material: Heat-resistant structural parts that replace metals.
4. New energy
-Lithium -ion battery: separator or electrode adhesive to improve high temperature safety.
-Fuel cell: proton exchange membrane or gas diffusion layer.
5. Emerging Fields
-Flexible display: the substrate or packaging layer of the OLED screen.
– 3D printing: high temperature resistant photosensitive resin (such as rapid molding of aerospace parts).
6. Other fields
-Medical : Implantable devices (such as pacemaker insulation).
-Industry : corrosion-resistant pump and valve, high temperature adhesive.
The development history of polyimide
Polyimide is the earliest special engineering plastic to be developed in practical terms, and its development history can be roughly divided into the following stages:
1. Early research and discovery (mid-20th century)
The 1950s : The synthetic foundation of polyimide began to form.
-Scientists have prepared polyimide for the first time by studying the polycondensation reaction of aromatic dianhydride and diamine.
– DuPont occupies an important position in research in this field, applied for the world’s first practical polyimide product patent (US2710853A) and developed early polyimide materials.
1960s : Commercialization breakthrough.
-DuPont launches its first commercial polyimide film Kapton® (1965), which is rapidly used in the aerospace and electronics sectors due to its excellent high temperature resistance (-269°C to +400°C) and electrical insulation and is rapidly used in the aerospace and electronics sectors due to its excellent high temperature resistance (-269°C to +400°C) and electrical insulation. . Subsequently, molding materials (Vespel®) and varnishes (Pyre ML®) were gradually commercialized, gradually establishing their leading position in the polyimide industry.
– NASA’s use of Kapton films as an insulating material in the Apollo program marks the validation of the application of polyimide in extreme environments.
2. Application expansion and performance optimization (1970–1990s)
Aerospace:
-Polyimide is used in aircraft engine components, satellite thermal coatings and spacecraft insulation, replacing traditional metal materials to reduce weight.
– PMDA-ODA type polyimide (based on phenylatic dianhydride and 4,4′-diaminodiphenyl ether) has become the mainstream structure.
The rise of electronics industry:
– Polyimide films (such as Kapton®) are used as substrate and cover for flexible circuit boards (FPCs), supporting the development of miniaturization of consumer electronics.
-Photosensitive polyimide (PSPI) emerged in the 1980s, simplifying the patterning process in microelectronics processing.
High-performance fibers and composite materials:
– Polyimide fibers (such as P84®) have been developed for high temperature filter materials and protective clothing.
-Resin -based composites are emerging in high-temperature adhesives and structural components.
3. Chemical Structure Innovation and Diversification (1990–2010s)
Soluble polyimide:– Improve the processability of traditional polyimides by introducing flexible segments (such as hexafluorodihydride) or asymmetric monomers, so that they can form films by solution method.
-Typical representative: BPDA-PPD polyimide** (developed by Ube Hitomori, Japan).
Functional modification:-Add nanofillers (such as graphene, carbon nanotubes) to improve mechanical properties or conductivity.
-Develop low dielectric constant (low-k) polyimide to meet high frequency communication needs.
Biomedical applications:-Polyimide is used in implantable medical devices (such as neural electrodes) for its biocompatibility.
4. Greening and emerging applications (2010s to present)
Environmentally friendly monomer and process:– Reduce the use of toxic solvents and develop aqueous polyimides or bio-based monomers (such as diamines derived from vegetable oils).
– Research on recyclable polyimides is gradually emerging.
Extreme environment applications:– Further expansion in deep space exploration (such as rover insulation materials), nuclear industry protective layers, etc.
-Radiation – resistant polyimide is used in semiconductor packaging.
Flexible electronics and new energy:-As the base material for flexible display screens (OLEDs).
– Play a role in lithium-ion battery separator and fuel cell proton exchange membrane.
3D printing technology:-High temperature resistant polyimide resins are used in additive manufacturing to manufacture complex structural components.
Contributions of other chemical manufacturers in the field of polyimide:
After DuPont launched its first commercial polyimide film Kapton® in the 1960s, Rona Planck, France, NASA, Amoxo, General Plastics (in 2007 by Cháber Basics Acquisition), Japan’s Jongyuan Chemical Co., Ltd., Ube Yoshisan Co., Ltd., DuPont-Toray Company, Mitsui Chemical Co., Ltd., Mitsubishi Gas Chemical Co., Ltd., South Korea’s SKC Kron, and Taiwan’s Damai Technology have all participated in the gathering The research and development and application of imide resins have successively launched a series of commercial resin varieties, greatly enriching the product types of polyimides.
At present, DuPont, DuPont-Tongli, Zhonghua, Ube Xingchan, SKC Kron and Damai are the world’s most important polyimide manufacturers, including DuPont, DuPont-Tongli, Zhonghua and Ube Xingchan. The company’s sales account for about 70% of the global total polyimide sales.
Polyimide production capacity and market size
1. Global production capacity and distribution
1. Global total production capacity
As of 2023, the global annual production capacity of polyimide (mainly films) is about 25,000 to 30,000 tons, of which high-end products (such as electronic-grade PI films) account for about 60%.
United States: DuPont, General Electric and other companies are dominated by companies, accounting for about 35% of the production capacity.
Japan: Ube Yokomoto (Ube), Kaneka and other companies have leading technology, accounting for about 30% of the production capacity. China: In recent years, it has expanded rapidly, with production capacity increasing to about 25%, but high-end products still rely on imports.
South Korea: SKC Kolon PI and other companies focus on the electronics field, accounting for about 10% of the production capacity.
2. Capacity expansion trend
Chinese manufacturers (such as Ruihuatai, Times New Materials, and Guofeng New Materials) are accelerating production expansion, and it is expected that China’s PI film production capacity will account for more than 40% of the world in 2025.
Overseas companies maintain high-end market advantages through technology monopoly (such as DuPont’s Kapton® film).
2. Market size
1. Global Market
The global polyimide market size is about US$2.5 billion in 2022 and is expected to reach US$5 billion by 2030. Main growth drivers: flexible electronics (folding screen mobile phones), 5G communications, new energy vehicles, and aerospace demand.
2. Chinese market
The market size of China’s polyimide is about 8 billion yuan in 2022 , and is expected to exceed 15 billion yuan in 2025.
Domestic substitution accelerates: Domestic companies are gradually replacing imports in the mid- and low-end markets, but the import dependence of high-end products (such as ultra-thin electronic grade PI films) is still more than 70%.
Industry demand for polyimide
Traditional polyimide films, such as DuPont’s Kapton® film, Ube Xing’s Upilex® film and benign Apical® film, due to its conjugated aromatic ring structure in its polyimide resin backbone The presence of the traditional polyimide film is prone to form intramolecular and intermolecular charge transfer complexes. Therefore, the light absorption of traditional polyimide films in the ultraviolet-visible light region is obvious, the light transmittance is poor, and the characteristic yellow color is shown.
The existence of the above inherent defects seriously affects and restricts the potential application of polyimide films in solar panels, flexible printed circuit boards, flexible displays, space insulation films, and photosensitive materials. Therefore, how to improve the transparency of polyimide films while reducing or eliminating their characteristic yellow color, thereby obtaining a polyimide film CPI that has both heat resistance and non-transparency has always been an urgent solution to the industry. Technical issues.
How to get colorless transparent polyimide
To obtain colorless and transparent polyimide, monomer regulation must be carried out before the polyimide synthesis, disrupting the conjugation interactions in the molecular chain, and eliminating the charge transfer (CT) phenomenon from the molecular structure.
However, reducing the production of charge transfer complexes (CTCs) from the structural design to achieve good optical properties will be accompanied by changes in other properties. Therefore, in order to obtain high-performance transparent PI, suitable molecular designs are needed to achieve a balance of optical transparency and other properties.
At present, the formation of CTC is mainly inhibited by introducing fluorine-containing groups, alicyclic structures, non-coplanar structures, meta-substituted structures, sulfone groups, etc. on the polyimide main chain, thereby improving the permeability of the polyimide film . Lightness, reducing the yellow index of the film. The CPI films prepared accordingly can be divided into fluorine-containing, alicyclic, non-coplanar, etc.