Aramid paper becomes the main development force of aerospace

With the increase in the application fields of aramid paper, the aramid paper market is expected to have good development prospects. According to third-party public data, China's aramid paper consumption has increased from 2,742 tons in 2017 to 4,215 tons in 2021, and my country's aramid paper consumption is expected to reach 12,357 tons in 2028. The honeycomb structure is the best load-bearing structure in the aerospace field and will exist in the structural design of aircraft and spacecraft for a long time.

Aramid fiber is called "aromatic polyamide fiber". It has excellent properties such as ultra-high strength, high modulus, high temperature resistance, acid and alkali resistance, and light weight. Aramid fiber was successfully developed and commercialized by DuPont in the United States in the 1960s. Aramid fiber will not be used directly as a final product. At least it must be made into fabrics or corresponding composite materials before it can be used. The category and performance of aramid fiber have a relatively large impact on the performance of the final product. Aramid fiber can be divided into three types: ortho-aramid, para-aramid (aramid 1414, PPTA) and meta-aramid (aramid 1313, PMTA). Among them, the industrialized products are mainly meta-aramid and para-aramid. Aramid paper made of pure meta-aramid has high strength, low deformation, high temperature resistance, chemical corrosion resistance, flame retardancy and excellent electrical insulation properties, and is widely used in defense, aerospace, high-speed trains and electrical insulation. Para-aramid has better comprehensive properties than meta-aramid. It can be used in the aerospace industry to manufacture solid rocket engine shells for missiles and secondary structural materials for large aircraft (such as cabin doors, windows, wing-related parts, etc.), bulletproof vests, bulletproof helmets, stab-proof and cut-proof clothing, bomb disposal clothing, high-elasticity parachutes, bulletproof car bodies, armor plates, etc. in the defense industry.

From aramid fiber to aramid honeycomb core material, a series of production processes such as papermaking and hot pressing are required. According to the process and production flow, it mainly involves aramid paper, aramid honeycomb core materials and other products. Aramid paper is a high-performance new material made from paper-grade aramid fiber through wet forming, high-temperature finishing and other processes. DuPont successfully developed aramid paper in the 1960s. Because of its excellent properties such as inherent flame retardancy, insulation, high temperature resistance and high strength, it has gradually become an indispensable key material for the development of important industries and fields such as national defense, aerospace, electric power, rail transportation, new energy, and electronic communications.

Aramid honeycomb is a bionic structure made of aramid paper through a series of complex processes such as gluing, laminating, hot pressing, trimming, stretching, shaping, dipping, and curing. It has the hexagonal structure of a natural honeycomb. It is lightweight, high-strength, high-modulus, strong structural stability, and has the advantages of sound insulation, heat insulation, and flame retardancy. It can be used as a lightweight and high-strength structural material (mainly as a core material) and applied in key areas such as aerospace, rail transportation, and national defense. Aramid honeycomb core material has become an important weight-reducing material in the fields of aerospace, rail transportation, and other fields due to its excellent performance. at the same time, combined with prepreg, it occupies an important position in the field of wave absorption.

Honeycomb sandwich structure absorbers based on honeycomb core materials are important structural absorbers. Honeycomb sandwich absorbers are mainly used in the field of radar stealth. they are composed of aramid honeycombs impregnated with absorbers and wave-transmitting panels, and have both excellent mechanical properties and absorbing properties. As for aramid honeycomb sandwich absorbers, their absorbing properties mainly depend on the specifications and dimensions of the honeycombs themselves and the impregnation glue system. At present, aramid honeycomb sandwich absorbers can form strong absorption in the frequency band of 0-18GHz.

Meta-aramid paper series products are mainly used in the field of electrical insulation, and a small amount is used in the field of honeycomb core materials. transformers are currently the field where aramid paper is used more in my country. At the same time, with the electrification of railways in my country and the large-scale construction of urban subways and light rails, higher requirements have been put forward for related equipment of high-speed trains, including high-power traction transformers.

Para-aramid paper series products are mainly used in the field of honeycomb core materials. Compared with honeycomb core materials made of meta-aramid paper, the comprehensive mechanical properties of honeycomb core materials made of para-aramid paper are significantly improved compared with meta-aramid paper honeycomb core materials. Its strength is 5 times that of steel of the same quality, but its density is only one-fifth of that of steel. however, due to its high cost, it is generally used in the field of honeycomb core materials with higher strength requirements.

2. Main application scenarios of aramid honeycomb core materials
Aviation field: After aramid paper honeycomb core materials are combined with panels to form a sandwich structure, they can be used as one of the ideal structural forms and are widely used in the aviation field. The main application parts include flaps, ailerons, vertical tail leading edges, rudders, canards, fuselages, blades, radomes, radomes, wall panels, doors, floors and other parts, as well as large rigidity and secondary load-bearing parts of aircraft. As the preferred core material for aircraft composite honeycomb sandwich structures, it can reduce the structural mass of the aircraft and achieve wave transmission, noise reduction and heat insulation performance of functional components. According to statistics, there are more than 280 Nomex honeycomb panels in the domestic Z-9 aircraft, covering about 80% of the entire aircraft. the honeycomb panels of the US F-111 fighter account for more than 90% of the entire external area. C919 uses a large number of honeycomb core materials in multiple parts of the aircraft to meet the need for weight reduction. The demand for aramid honeycomb core materials for a single flight is expected to be more than 10 million yuan.

Ship field: Honeycomb sandwich structures can not only reduce the weight of empty ships, improve the maneuverability and impact resistance of ships, but also greatly improve the corrosion resistance and "stealth" capabilities of ships. In recent years, navies of various countries have also used honeycomb sandwich materials for superstructures such as deckhouses, bulkheads and aircraft ceilings of surface ships to improve the comprehensive performance of ships in all aspects. The US Coast Guard cutter uses Nomex honeycomb structure to replace asbestos board, which not only reduces the weight of the cutter by more than 9 tons, but also eliminates the potential hazards caused by asbestos. the interior decoration of the Liaoning aircraft carrier uses more than 100,000 square meters of aramid sheets, with a price of 1,500-2,000 yuan per square meter. It is understood that major research institutes of China Shipbuilding Industry Corporation have begun to use aramid honeycomb sheets as lightweight ship interior decoration projects.

Rail transit field: Aramid materials can effectively reduce the energy consumption and noise of high-speed trains. They have been used in the side panels, roof panels, seats, partitions, luggage racks and skylight panels of high-speed rail vehicles to reduce vehicle weight and increase train speed. EMUs with speeds above 200 kilometers per hour need to use a large amount of aramid paper honeycomb materials. Changchun Passenger Car Factory CRH-5 EMU recommends the use of aramid honeycomb materials as sandwich structure materials for high-speed trains, with an annual demand of 10-15mm aramid honeycomb materials of 50,000 square meters. in addition, new models such as standard EMUs, sleeper cars, and new energy low-floor cars also use aramid honeycomb structures in interior design to meet the needs of lightweight and comfort.

In addition, aramid paper honeycomb core materials can also be used in the manufacture of wind turbine blades, ships and yachts, racing boats, skis, RVs and other products.

At present, the global aramid fiber production capacity is about 140,000-150,000 tons, of which more than 50,000 tons are meta-aramid fibers and 90,000-100,000 tons are para-aramid fibers. In terms of meta-aramid fibers, about 60% of them are used in relatively low-end industrial filtration fields in China, and only about 10% are used in high-end insulation and honeycomb core materials. In terms of para-aramid fiber, 40% is used for optical fiber reinforcement in China. 20% is used for bulletproof protection, military bulletproof helmets, gloves, etc. 20% is used in the automotive rubber industry. and 20% is used in composite materials.

Aramid paper: According to statistics, the nominal production capacity of aramid paper in the world is about 20,000 tons/year, and the effective production capacity is about 12,000 tons/year. the global demand for aramid paper is about 10,000 tons/year, and the main market share is occupied by DuPont. According to data compiled by CITIC Securities Research Institute, the world's aramid paper is mainly used for electrical insulation and honeycomb core materials, accounting for 64% and 34% respectively. benchmarking the global consumption structure, 90.76% of my country's aramid paper demand in 2020 comes from electrical insulation, while the consumption of honeycomb structural materials and other composite materials accounts for only 9.24%.

At present, the main domestic aramid paper manufacturer is Minshida. Minshida is the first aramid paper manufacturer in China. At present, its global market share of aramid paper products ranks second, second only to DuPont in the United States.

According to the calculation that a 100kg piece of aramid paper can be made into 3 cubic meters of honeycomb core materials, the theoretical production capacity of aramid honeycombs in the world can reach 2.04 million cubic meters, and the theoretical production capacity of aramid honeycombs in the Chinese market can reach 240,000 cubic meters. the aramid honeycomb core materials corresponding to the effective production capacity are about 54,000 cubic meters.

At present, the main domestic manufacturer of aramid honeycomb core materials is AVIC Composites. AVIC Composites' honeycomb production is mainly distributed in Beijing and Nantong. Among them, Nantong's large-size honeycomb production line has an internationally advanced level and a high degree of automation. its products are mainly for the civil aircraft field, and mainly for foreign trade customers such as Airbus, Boeing, and Yaqi.

In recent years, my country has continued to increase its policy support for aramid fiber materials and aramid paper. In particular, the rapid development of my country's high-speed trains, domestic aircraft manufacturing, aircraft carriers and other equipment manufacturing industries in recent years has driven the development of aramid insulation paper and aramid paper honeycomb core materials.

With the increase in the application fields of aramid paper, the aramid paper market is expected to have good development prospects. According to third-party public data, China's aramid paper consumption has increased from 2,742 tons in 2017 to 4,215 tons in 2021, and is expected to reach 12,357 tons in 2028. The honeycomb structure is the best load-bearing structure in the aerospace field and will exist in the structural design of aircraft and spacecraft for a long time.