Question: What year was the high strength synthetic fiber, which was the subject of a lawsuit between DuPont and Kolon Industries, developed?

full_context: Document 1: DuPont: E. I. du Pont de Nemours and Company, commonly referred to as DuPont, was an American conglomerate that was founded in July 1802 as a gunpowder mill by American chemist and industrialist Éleuthère Irénée du Pont.
Document 2: Acrylic fiber: Acrylic fibers are synthetic fibers made from a polymer (polyacrylonitrile) with an average molecular weight of ~100,000, about 1900 monomer units. For a fiber to be called "acrylic" in the US, the polymer must contain at least 85% acrylonitrile monomer. Typical comonomers are vinyl acetate or methyl acrylate. DuPont created the first acrylic fibers in 1941 and trademarked them under the name Orlon. It was first developed in the mid-1940s but was not produced in large quantities until the 1950s. Strong and warm, acrylic fiber is often used for sweaters and tracksuits and as linings for boots and gloves, as well as in furnishing fabrics and carpets. It is manufactured as a filament, then cut into short staple lengths similar to wool hairs, and spun into yarn.
Document 3: Kolon Industries: Kolon Industries is a Korean manufacturing company. It was founded in 1957 as Korea Nylon Inc., an early manufacturer in the Korean nylon industry. It has since expanded to produce chemicals, other materials and fashion. In 2015 Kolon Industries opened a shopping mall built with shipping containers, the first of its kind in South Korea. It has a US subsidiary, Kolon USA Inc., selling polyester film and nylon film.
Document 4: Vinyon: Vinyon is a synthetic fiber made from polyvinyl chloride. In some countries other than the United States, vinyon fibers are referred to as polyvinyl chloride fibers. It can bind non-woven fibers and fabrics. It was invented in 1939.
Document 5: Setralit: Setralit is a technical natural fiber based on plant fibers whose property profile has been modified selectively in order to meet different industrial requirements. It was first manufactured in 1989 by Jean-Léon Spehner, an Alsatian engineer, and further developed by the German company ECCO Gleittechnik GmbH. The name “Setralit“ is derived from the French company Setral S.à.r.l. which is a subsidiary company of ECCO, where Spehner was employed at that time. Setralit was officially described first in 1990.
Document 6: DuPont v. Kolon Industries: DuPont v. Kolon Industries is an intellectual property lawsuit centering on the allegation that Kolon Industries (of ), a South Korea-based company, stole trade secrets concerning the production and marketing of Kevlar from DuPont, an American chemical company. Kevlar is a high strength synthetic fiber used in applications as diverse as bicycle tires and body armor. On September 14, 2011, a jury found in favour of DuPont and awarded damages of $919.9 million. A 2015 settlement reduced the damages to $275 million.
Document 7: Starlite: Starlite is a material claimed to be able to withstand and insulate from extreme heat. It was invented by amateur chemist and hairdresser Maurice Ward (1933–2011) during the 1970s and 1980s, and received much publicity in 1993 thanks to coverage on the science and technology show "Tomorrow's World". The name Starlite was coined by Ward's granddaughter Kimberly.
Document 8: Vinylon: Vinylon, also known as Vinalon, is a synthetic fiber produced from polyvinyl alcohol, using anthracite and limestone as raw materials. Vinylon was first developed in 1939 by Ichiro Sakurada, Ri Sung Gi, and H. Kawakami. Production of this fiber was delayed for World War II. The fiber was largely ignored in Korea until Ri defected to North Korea in 1950. Trial production began in 1954 and in 1961 the massive February 8 Vinylon Complex was built in Hamhung. Vinylon's widespread usage in North Korea is often pointed to as an example of a success of the "juche" philosophy, and it is known as the "juche" fiber.
Document 9: Polybenzimidazole fiber: Polybenzimidazole (PBI, short for poly[2,2’-("m"-phenylen)-5,5’-bisbenzimidazole]) fiber is a synthetic fiber with a very high melting point. It has exceptional thermal and chemical stability and does not readily ignite. It was first discovered by American polymer chemist Carl Shipp Marvel in the pursuit of new materials with superior stability, retention of stiffness, toughness at elevated temperature. Due to its high stability, polybenzimidazole is used to fabricate high-performance protective apparel such as firefighter’s gear, astronaut space suits, high temperature protective gloves, welders’ apparel and aircraft wall fabrics. In recent years, polybenzimidazole found its application as a membrane in fuel cells.
Document 10: Kevlar: Kevlar is the registered trademark for a para-aramid synthetic fiber, related to other aramids such as Nomex and Technora. Developed by Stephanie Kwolek at DuPont in 1965, this high-strength material was first commercially used in the early 1970s as a replacement for steel in racing tires. Typically it is spun into ropes or fabric sheets that can be used as such or as an ingredient in composite material components.
Document 11: Taklon: Taklon is the common name for a synthetic fiber used in artist-quality paint, makeup and pin stripe brushes. It is a smooth, soft, and somewhat fragile polyester derivative devoid of any protein component or allergen elements and is therefore used in the cosmetic industries as a "green," "vegan," "allergy free" or synthetic alternative to animal hair brushes.
Document 12: M5 fiber: M5 fiber (polyhydroquinone-diimidazopyridine or PIPD) is a high-strength synthetic fiber first developed by the Dutch chemical firm AkzoNobel. It is produced in the United States by the Magellan Systems International, which became a division of DuPont.
Document 13: Reinforced thermoplastic pipe: Reinforced thermoplastic pipe (RTP) is a generic term referring to a reliable high strength synthetic fibre (such as glass, aramid or carbon), initially developed in the early 1990s by Wavin Repox, Akzo Nobel and by Tubes d'Aquitaine from France, who developed the first pipes reinforced with synthetic fibre to replace medium pressure steel pipes in response to growing demand for non-corrosive conduits for application in the onshore oil and gas industry, particularly in the Middle East.
Document 14: Terephthaloyl chloride: Terephthaloyl chloride (TCL, 1,4-benzenedicarbonyl chloride) is the acid chloride of terephthalic acid and is one of two monomers used to make Kevlar(R), the other being p-phenylenediamine. Its CAS reference number is 100-20-9 and its chemical formula is C H Cl O .
Document 15: Microfiber: Microfiber (or microfibre) is synthetic fiber finer than one denier or decitex/thread. This is smaller than the diameter of a strand of silk (which is approximately one denier), which is itself about 1/5 the diameter of a human hair. The most common types of microfibers are made from polyesters, polyamides (e.g., nylon, Kevlar, Nomex, trogamide), or a conjugation of polyester, polyamide, and polypropylene. Microfiber is used to make mats, knits, and weaves for apparel, upholstery, industrial filters, and cleaning products. The shape, size, and combinations of synthetic fibers are selected for specific characteristics, including softness, toughness, absorption, water repellency, electrostatics, and filtering capabilities.
ground_truth: 1965