China's High Strength And High Modulus Polyethylene Fiber: Application Range And Product Quality Need To Be Improved.

　　 High strength and high modulus polyethylene fibers have an unusual high strength "character". We use a pair of stainless steel scissors to cut high strength and high modulus polyethylene fibers. After a continuous shearing for a minute, the knife edge will be passivated. In addition, the free fracture length of high strength and high modulus polyethylene fibers in water is infinite. Under the same thickness, it can withstand 8~10 times the maximum mass of steel wire rope. The strength of this polyethylene fiber is 15 times higher than that of steel. If it is calculated by mass, its strength is 40% higher than that of aramid fiber. It can be called the highest strength fiber in the world today. Therefore, it has become the third generation of ultra-high strength fibers after carbon fiber and aramid fiber.

Internationally, the main application fields of high-strength polyethylene fiber and its composite products include: national defense. Quartermaster Such as aircraft, tanks, armored vehicles and all kinds of chariots, ships, light bulletproof armor plates; safety protection, such as light weight. Bulletproof vests Lightweight bulletproof helmets, stab resistant clothing, anti cut garment fabrics, and anti cutting. glove Such as ocean engineering, such as ships, ships, deep-sea fishing, deep-sea natural gas, oil drilling platforms, Gao Qiangsheng cables and fishing nets. In addition, high performance composite materials made from high-strength polyethylene fibers have been applied in aviation, aerospace and sports equipment, and have broad prospects for development.

At present, the high strength and high modulus polyethylene fibers produced by our country have been successfully applied to bulletproof armor, bulletproof helmets and bulletproof armor plates used by military police. The quality of the bulletproof vest is lighter and higher than that of the traditional bulletproof vest. It can be said that it has played a great role in the safety protection industry. In addition, the Shenzhou 5 parachute system also applied this technology. However, due to the limitation of cost and development capability, the application scope of domestic products is still limited to traditional safety protection and cable industry.

　　 The contest between two and ten families

At present, China is the third country that can produce high strength and high modulus polyethylene fibers after Holland and the United States. The representatives of the two countries are Holland's DSM and Honeywell (HONEYWELL) of the United States. Dyneema, a well-known brand in the field of high strength and high modulus polyethylene fiber, is owned by Dsm company. Dsm company has become the world's largest manufacturer of Dyneema brand high performance polyethylene (HPPE) fibers. Honey Well Company is the second company to successfully produce high-strength polyethylene fibers after Dsm company. Although the strength of the HDPE fiber is higher than that of the same product, it has a higher modulus than the latter. In terms of downstream applications, Honey Well Company is leading in the field of bulletproof research. It is widely used in high-strength polyethylene fiber weft cloth for bulletproof vest and bullet proof helmet, which was first developed by Honeywell.

To maintain its leading position in the world, Dsm company in Holland has invested a lot of money in research and development, and has also set up branches worldwide to meet the needs of customers in different regions and different fields. According to data from Shanghai golden autumn energy and petrochemical studio, since 90s of last century, Dsm company's high strength polyethylene fiber production capacity has maintained rapid growth. In 2008, its factory capacity in Europe and the United States reached 4500 tons / year, and the capacity of Japanese joint venture factory reached 1600 tons / year (joint venture with Toyo textile company of Japan). In 2010, the production of high-strength polyethylene fiber from the Dsm company in Europe and the United States will reach 6000 tons per year, and the capacity of the Japanese joint venture will also reach 3200 tons per year. In addition, the company also has a specialized applied research and market development team, which plays a leading role in the development of high-strength polyethylene fiber application.

The Honey Well Company's high-strength polyethylene fiber production capacity as of 2009 also reached 1000 tons / year, and its capacity is expected to reach 3000 tons / year in 2010.

In view of China's incomplete statistics, there are ten enterprises that can produce high strength and high modulus polyethylene fibers at present. They are Beijing Zhongyi special fiber technology development Co., Ltd., Hunan Zhongtai special equipment Co., Ltd., Ningbo Dacheng new material Limited by Share Ltd, Yizheng chemical fiber company, Shanghai Sri Polymer Technology Co., Ltd., Jiangsu Changshu embroidery Fiber Co., Ltd., Shandong Aidi polymer materials Co., Ltd., Hangzhou southeast Chemical Fiber Co., Ltd., Hangzhou Xiangsheng Textile Co., Ltd., and Wei Ya High Performance Fiber Co., Ltd. Some of these enterprises are state-owned enterprises and some belong to private capital enterprises.

These enterprises, on the basis of joint efforts with universities and research institutes, have achieved varying degrees of achievement in the development and industrialization of high strength and high modulus polyethylene fibers.

Ningbo Dacheng company is an early realization of the industrialization of high-strength polyethylene production enterprises. Its industrialization began in 1996. In terms of technology, in order to avoid foreign patent technology, the company and Donghua University jointly tackled the problem, and finally formed a complete set of independent intellectual property technology system including process route, spinning solvent and production equipment. By the end of 2009, Dacheng, Ningbo, had formed an annual output of 1500 tons of high-strength polyethylene fiber, 200 thousand sets of bulletproof vests and bulletproof helmets, 300 tons of bulletproof armor plates, 6 million pairs of anti cutting gloves, 300 tons of high-strength ropes, and 200 tons of high performance composite materials, and most of its products were exported. At present, the British forces in Iraq, the Kuwait force, the new army, the police and some of the troops in Saudi Arabia are using bullet proof equipment manufactured by Ningbo Dacheng.

At present, high strength and high modulus polyethylene fibers have two technological routes, one is the high volatile solvent dry gel spinning route, the other is dry route, the other is the low volatile solvent hydrogel spinning route, or the wet route. High strength and high modulus polyethylene fibers produced by dry spinning process have less solvent content, higher strength and better creep resistance, so they are mostly used in high-end products. Compared with wet process, dry spinning process has the characteristics of short process, environmental protection and high comprehensive performance index. Therefore, this technology has been monopolized by foreign enterprises represented by Dsm company.

It is listed as Sinopec's "ten dragons" tackling key project. The 300 ton / year high performance polyethylene fiber dry spinning technology integrated technology developed by Yizheng chemical fiber company, Nanhua group company research institute and China Textile Science Research Institute was technically identified by Sinopec joint stock company in November 2009. The successful development of the technology fills the gap of the domestic high-performance polyethylene fiber dry process, and breaks the monopoly of foreign technology.

According to Professor Liu Zhaofeng, Professor of Chemical Fiber Research Institute of Donghua University, at present, China's high strength and high modulus polyethylene fiber production capacity has accounted for about 1/3 of the world's total output. From this we can infer that the total output of ten enterprises in our country only accounts for the output of 1/3 in the world, while the DSM and Honeywell companies account for 2/3 output. This shows that our enterprises are small in scale and low in output.

　　 The gap between 1000 yuan and 10000 yuan

According to the survey, behind the domestic high strength and high modulus polyethylene fiber inventory backlog and low price competition, it is an embarrassing situation of low profit margins and insufficient equipment start-up.

It is understood that some domestic enterprises sell a ton of high-strength high modulus polyethylene fiber profit only about 1000 yuan, while the profits of foreign tons of products are as high as 3~4 million yuan.

The same is high-tech fiber. Why are our profits so low? The quality of products is a gap that is not allowed to pass between high and low profits after deducting brand influence. According to Professor Liu Zhaofeng of Donghua University, compared with the similar products abroad, China's products have higher irregularity in fiber strength and fineness; resin quality is unstable, fiber grade special resin is not stable, fiber mechanical properties are insufficient, indicators only reach the middle level of similar products in developed countries, lack of fiber surface modification technology, resulting in poor performance of composite materials, low capacity of single set of equipment, and easy to cause fiber quality fluctuations.

Qian Bozhang, founder of Shanghai golden autumn energy and petrochemical studio, believes that although the annual demand for high-strength polyethylene fiber will reach 100 thousand tons in the next 10 years, the direct output value of the fiber will reach 30 billion yuan, and the downstream product output value will be 100 billion yuan. However, due to the limitation of cost and development capability, the application scope of domestic products will still be limited to the traditional safety protection and cable industry, and the new application area needs to be further developed and cultivated. Because the progress of downstream development is not up to the speed of capacity expansion, a large number of overcapacity and idle equipment have appeared in China, and most of the producers are underemployed.

On the product side, although the enterprise has accumulated a lot of valuable production experience, the quality of the product has not been able to achieve the ideal state. At present, the domestic high-strength polyethylene fiber industry is still in the initial stage of development, and the market players are not yet mature. Most of them are in a state of spontaneous blindness. Constrained by the capital conditions, many enterprises are trying to get investment returns as soon as possible, and adopt a saving way in equipment investment and product development. This will inevitably bring great negative effects on their product quality, and even fall into a vicious circle.

In order to realize the sustainable development of high strength polyethylene fiber industry, many experts suggest that the combination of production, teaching and research should be carried out at the most urgent task. Through tackling key problems in science and technology, we can enhance the quality of resin and product, improve its heat resistance and creep resistance, expand the scope of application of high-strength polyethylene fiber, open up new production processes and manufacturing methods, strive to reduce manufacturing costs and reduce product prices, strengthen industry self-discipline, avoid disorderly investment and waste of production capacity, focus on strengthening the research of high-strength polyethylene fiber composite materials, and expand the application of high-strength polyethylene fiber in the civil field, such as strengthening the core of large wind turbine blades, strengthening construction materials, strengthening building structures, strengthening fiber optic cables and medical materials.

Take the medical products as an example, a high-strength polyethylene fiber Dyneema Purity product developed by Dsm company, which is flexible and wear-resistant, has been developed. After making the surgical suture line, the diameter of the latter is 1/2 compared with the polyester wire of the same strength. The fiber can also be used to manufacture catheters for interventional therapy and endoscopic surgery. At present, imported products are widely used in China, and the price is very high. If the same kind of catheter can be produced in China, great economic benefits will be obtained.

Know the difference, and make progress.

It is believed that in the next five years, China's high strength and high modulus polyethylene fiber will have a qualitative improvement in its application scope and product quality.