Technology Promotion: Lanzhou Blue Star Conquers 1000 Ton 50K Industrialization Technology

With the launch of a new round of "western development" strategy, Xi'an, Lanzhou and other northwest cities are once again "eye-catching". In the field of carbon fiber, Lanzhou Blue Star Fiber Co., Ltd. (hereinafter referred to as "Lanzhou Blue Star fiber") has also attracted much attention due to its continuous breakthrough in the field of large tow carbon fiber industrialization in recent years.

Recently, there has been good news from the company. On July 22, China Textile Industry Federation organized the technical achievement appraisal of Lanzhou Blue Star fiber "Research on key technology and equipment for industrialization of 50K large tow carbon fiber by NaSCN process" of Lanzhou Blue Star fiber in the form of online video conference.

After the expert committee unanimously evaluated, the project passed the appraisal. The appraisal committee believes that "the overall technology of large tow carbon fiber production process has reached the international advanced level."

In fact, since the beginning of this year, some enterprises have announced that they will expand their investment in the field of large tow, some enterprises have announced that they will set foot in large tow, and the new large tow projects announced last year have also been promoted. Various signs show that large tow is becoming a new driving force for the vigorous development of China's carbon fiber market.

Lanzhou Blue Star conquers the technology of 50K industrialization of 1000 tons

Lanzhou Bluestar fiber is located in Gansu international port Park, Xigu District, Lanzhou city. It is subordinate to China Blue Star (Group) Co., Ltd. (hereinafter referred to as "Bluestar Group") under China National Chemical Corporation. The company adopts NaSCN one-step process to produce carbon fiber precursor, which has the characteristics of short process, low energy consumption and large single line production capacity. It is one of the representative enterprises that can realize low-cost and industrialized production of large bundle carbon fiber in China.

Xu Lianghua, vice president of School of materials science and engineering of Beijing University of chemical technology and director of national carbon fiber engineering technology research center, is one of the "star figures" in the industry. He once proposed the concept of "thousand ton club" to measure the industrialization level of China's carbon fiber enterprises, which means that leading enterprises have a single line capacity of 1000 tons of carbon fiber production lines. From this point of view, Lanzhou has become one of the large-scale carbon fiber production enterprises of "Blue Star".

Only with hard work can we reap. In fact, Lanzhou Blue Star fiber has been struggling in this field for more than 10 years. The time goes back to May 2009, 11 years ago. At that time, the hot summer in Northwest China had not yet arrived. Lanzhou Bluestar fiber, which was registered and established in 2008, with ambition for carbon fiber, began to build a factory in Xigu District of Lanzhou.

At that time, the domestic carbon fiber industry was still in the initial stage of industrialization. Since 2004, the price of carbon fiber in foreign countries has been rising continuously. The price of carbon fiber imported from foreign countries in China has risen rapidly to more than 8000 yuan / kg, and then exceeded 10000 yuan / kg. In 2005, due to the situation in the Taiwan Strait and other factors, China's import channels of carbon fiber were almost interrupted, and the domestic carbon fiber supply was cut off by foreign countries. In this period, the severe market situation has attracted much attention to carbon fiber, a strategic material, and also made many people understand its value connotation as the "king of new materials".

Perhaps it was precisely because of the market situation at that time that blue star group was determined to do a big job in the field of carbon fiber. At that time, the domestic carbon fiber industry was in the first round of investment, and all kinds of capital were eager to try, and blue star group became one of them. However, the future of enterprise development is still unknown. After all, we are "crossing the river by feeling the stone".

In the long 10-year period from 2003 to 2013, the whole domestic carbon fiber industry has worked hard to solve the problem of "from scratch". At this stage, China's carbon fiber industry has just taken the step of industrialization, and has been hobbling forward, while the enterprise competitors in Japan and other countries have gradually adopted the strategy of "the entry-level T300 products have been greatly reduced, and the high-level products have been greatly increased". The domestic carbon fiber industry in this period was basically in the "loss state of the whole industry". At that time, all of us were holding on to the blue star.

In 2012, Lanzhou Blue Star fiber production line with an annual output of 1500 tons of carbon fiber was successfully tested. In August 2013, its 5000t / a carbon fiber precursor production line was successfully put into operation. In July 2014, the 12K carbon fiber produced by Lanzhou Bluestar fiber reached the international quality standard of T700. In April 2016, its 1500 T / a carbonization plant realized continuous production and operation. In 2018, Bluestar Group invested hundreds of millions of yuan to carry out technical transformation on Lanzhou Blue Star fiber precursor production line, and the product was upgraded from 24K to 50K. In the second half of 2019, its 50K carbon fiber production line has passed through. Relying on the cost advantage of self-produced precursor and the R & D advantage of Beijing carbon fiber technology research center, the product has broken through the bottleneck of industrialization production of large tow carbon fiber in China.

At the recent appraisal meeting, Zhou Baoqing, Secretary of the Party committee and general manager of Lanzhou Bluestar Fiber Co., Ltd., introduced that the company has built a 50K large tow carbon fiber 1000 ton production line, among which, the annual production capacity of single strand precursor is 4000 tons, and the annual production capacity of carbon fiber is 1500 tons. The performance of the product meets the level of national standard gq3522, which can meet the preparation requirements of carbon fiber prepreg. The intrinsic performance and application process of the product are similar to those of similar imported products, which fills the market gap of domestic 50K carbon fiber products.

From May 2009 to 2020, a long 11 years have passed. In the vast land of Northwest China, Lanzhou Bluestar fiber has been bearing rich fruits step by step.

It is also understood that Lanzhou Bluestar fiber has signed a contract with Yiyuan County, Zibo City, Shandong Province in March this year, and the next phase II project in Yiyuan County will form an industrial scale with an annual output of 50000 tons of raw silk and 25000 tons of carbon fiber; in July, the company also signed a strategic cooperation agreement with Shangwei (Jiangsu) carbon fiber composite material Co., Ltd. on the production and manufacture of carbon fiber and its composite materials China will form long-term and comprehensive cooperation in wind power, automobile and other fields.

"We are committed to alleviating the current situation that domestic large tow carbon fibers still rely heavily on imports." Zhou Baoqing said.

The "charm" of large tow is great, but there are many difficulties

Large tow is an international carbon fiber manufacturing technology.

"The application of low-cost, large tow carbon fiber is the key to the development of low-cost carbon fiber composite technology research," an industry insider told reporters

1K, 2K, 3k, 6K, 12K, etc. in carbon fiber index refer to the number of monofilament in carbon fiber tow. According to the size of tow, carbon fiber can be divided into large tow and small tow. Generally speaking, the larger the K number, the more difficult the production and industrialization technology involved.

Small tow usually means that the number of single filaments in each carbon fiber bundle is less than 24000, such as 1000 (1K), 3000 (3K), 12000 (12K), etc. Large tow usually refers to the number of single filaments in each carbon fiber bundle greater than or equal to 48000 (48K), such as 50000 (50K), 60000 (60K), 120000 (120K), etc. 50K means that there are 50000 monofilaments in a carbon fiber bundle, which is a typical large tow.

What are the outstanding features of large tow? First, high production efficiency. Compared with small tow, the biggest advantage of large tow carbon fiber is that under the same production conditions, it can greatly improve the single line production capacity of carbon fiber and realize low cost production. Moreover, in the preparation process of carbon fiber composites, the laying efficiency is higher, and the production cost can be reduced by more than 30%.

"This will help to break through the application limitations of carbon fiber due to its high price, and lay a foundation for further expanding the application market of carbon fiber composites." One industry source said.

Second, the cost is lower and the performance is high. Polyacrylonitrile based carbon fiber precursor is currently used to prepare large tow carbon fiber in China. Generally, the cost of precursor is about 50% ~ 60% of the total cost of carbon fiber preparation. Therefore, the price of carbon fiber products with large tow can be controlled to 50% ~ 60% of that of small tow. At the same time, the main performance of some large tow carbon fiber products on the market has approached or even exceeded some small tow carbon fiber.

Yan Bing, technical director of Jiangsu Aosheng Composite Materials Technology Co., Ltd., introduced: "as an industrial grade carbon fiber, the core driving force of large tow is low cost. Therefore, under the premise of ensuring the quality stability of carbon fiber, how to effectively control the cost is extremely important. For example, the tensile strength and modulus of large tow carbon fiber pan-ex35 produced by zhuotec company is equivalent to that of Toray small tow T700 in performance, but the price is relatively low. In China's market, Toray T700 currently sells for about $20 per kilogram, while pan-ex35 costs about $156 per kilogram. "

Lin Gang, general manager of Guangzhou Saio Carbon Fiber Technology Co., Ltd., introduced: "we call the products with tensile properties close to T700 as high performance. At present, the performance of many high-performance and large tow products in the world is equivalent to that of T700. For example, the tensile strength of Mitsubishi trh50-60k in Japan has reached 4830mpa, and the tensile modulus has reached 250gpa; for a product from siegli, Germany, the tensile strength has reached 4800mpa and the tensile modulus has reached 280GPa. "

"In a short time, in terms of general performance, large tow carbon fibers with 48K and 50K specifications will be able to basically compete with T800. In recent years, the international market price of civil small tow products is about 15 US dollars / kg ~ 24 US dollars / kg, and that of large tow products is about 13 US dollars / kg ~ 14 US dollars / kg Lin Gang further predicted that "with the continuous development of low-cost innovative technology, the price of large tow products is expected to drop to 10 US dollars / kg ~ 12 US dollars / kg. Small tow is a traditional product, while large tow is a new product. Next, it's going to be how to fight between big and small tow. From the reality, in the future, large tow will gradually occupy the market share of small tow. Even in aerospace, which is a traditional strong application field of small tow, high-performance large tow will gradually open the application market. Even more cost-effective "giant tow (greater than 100k)" will join the competition of large tow

However, compared with small tow, the preparation technology of large tow carbon fiber is more difficult in the aspects of precursor, polymerization, preoxidation and carbonization.

In the precursor process, if 1K and 3K small tow carbon fibers are produced, there will be 1000 and 3000 holes on a spinneret, but if 48K large tow carbon fiber is produced, there will be 48000 holes in one spinneret, which is a certain challenge. At the same time, the stability of CV value is more difficult to grasp. Taking the production of 50K large tow carbon fiber as an example, the uniformity of each wire sprayed from 50000 holes on a spinneret is required to be the same, which is several times more difficult than that of small tow carbon fiber.

Carbonization is very important in the preparation of carbon fiber, which can be divided into low-temperature carbonization and high-temperature carbonization. With the change of material structure during carbonization process, the precursor wire is transformed into heat-resistant ladder structure pre oxidized wire after pre oxidation, and then converted into carbon fiber with random layer graphite structure after low-temperature carbonization and high-temperature carbonization.

"After the production of large bundle carbon fiber precursor, there are also many challenges in the carbonization process. In the carbonization process, the non carbon atoms will be gradually removed, and the carbon atoms will be enriched and recrystallized. For example, the wool problem may not be obvious in the raw silk link, but it may be highlighted in the carbonization process

Lin Gang stressed: "from 12K to 24K, the technological process is basically the same, but from 24K to 48K, a huge technical threshold has been crossed. One of the main differences between large tow technology and small tow technology is its high flux. Because of the problems of high flux, high technology and so on, it is easy to bring about many problems in the process of spinning, such as high carbon flux, high polymerization time and so on

"Although the continuous performance of large tow carbon fiber is not better than that of aerospace grade small tow carbon fiber, its technical barrier is also quite high, which to a large extent leads to the current global output of large tow carbon fiber lower than that of small tow carbon fiber." Yan Bing said, "in addition to the high technical requirements for preparation, in the follow-up application process, due to the large fiber tow and easy to gather, the yarn spreading effect of carbon fiber with large tow will be affected, which will easily lead to the defects such as poor wettability of resin on the fiber and the generation of pores. At the same time, in the process of developing large tow carbon fiber, it is more likely to have disordered yarn and broken yarn, which leads to the increase of dispersion of mechanical properties of fiber, which further increases the application difficulty of large tow carbon fiber

According to another introduction, at present, the "thin layer" technology of large tow carbon fiber has been developed at home and abroad. After thin layer treatment, the thickness of large tow carbon fiber can be thinner, the distribution of fiber in preform is more uniform, the permeability of preform is reduced and the uniformity is improved. Moreover, the internal defects of large tow carbon fiber reinforced resin matrix composites are reduced after the thin layer treatment, and the fiber / resin distribution is more uniform.

Large tow is becoming the hot spot of global carbon fiber market competition

From the global market of large tow carbon fiber, Zoltek, a well-known carbon fiber enterprise in the United States, still has an absolute advantage, but it has been acquired by Toray company of Japan before.

In fact, over the years, well-known companies around the world have been adding large tow. In February 2014, Toray of Japan completed the acquisition of droltek for us $584 million, strengthening its supply capacity of low-cost, large tow carbon fiber. In April 2018, Toray of Japan announced that it would increase the large tow carbon fiber production capacity of its U.S. subsidiary droltek, increasing the production capacity of droltek in Hungary from 10000 tons per year before to 15000 tons per year; since then, Toray has also announced that it will increase the annual production capacity of droltek in Mexico from 5000 tons to 10000 tons per year.

In November 2017, Solvay completed the acquisition of European carbon fiber GmbH, a manufacturer of high-quality PAN based carbon fiber precursor with large tow (50K). In December 2019, Solvay announced that it had reached a joint development agreement with German carbon fiber manufacturer SGL to expand the application of large tow (50K) and medium modulus carbon fiber composites in the civil aviation market.

The market demand for wind turbine blades has increased greatly, which has led to the rapid heating of large tow. ?

In China's market, in addition to Lanzhou Bluestar fiber, at present, the main manufacturers with large tow carbon fiber production capacity are Jilin Carbon Valley Carbon Fiber Co., Ltd., Jilin Jinggong Carbon Fiber Co., Ltd., Shanghai Petrochemical Co., Ltd. Especially in recent years, with the "Leaping" large-scale demand of large tow carbon fiber for wind turbine blades, the demand of domestic large tow carbon fiber market is rapidly rising, which also drives the continuous breakthrough of carbon fiber preparation technology and industrialization technology, as well as the rapid expansion of industrial scale.

"In the total market demand of carbon fiber in China in 2019, the capacity of small tow will be about 18000 tons, of which 7000 tons will be produced by mainland enterprises; the market capacity of large tow will be about 14000 tons, of which 1000 tons will be produced by mainland enterprises, and the rest will be mainly imported," Lin Gang said

Jilin Carbon Valley is the "pioneer" of industrialization. In 2019, the project of "key technology and industrial development of 25K ~ 50K PAN based precursor and carbon fiber" passed the appraisal, and the overall technology of the project reached the international advanced level.

The project has developed the core technology and key equipment for industrialization of large tow carbon fiber (25K ~ 50K), developed the DMAC wet "two-step" spinning technology for preparing homogeneous structure precursor, and realized the stable production of 5000 ton grade 25K ~ 50K precursor; developed the constant tension control technology of large tow fiber in preoxidation process, combined with intelligent temperature control and automatic decoking process, realized single strand Stable production of 25K ~ 50K carbon fiber of 2000 tons. The company has an annual production capacity of 16000 tons of carbon fiber and has independent intellectual property rights.

The reporter learned that since 2019, the market demand of Jilin Carbon Valley's large tow precursor has increased rapidly, and the scale effect has gradually emerged. According to the latest semi annual report released by Jilin Carbon Valley, in the first half of this year, despite the impact of the epidemic, its main business income rose against the trend to 213 million yuan, a sharp increase of 58.08% year-on-year; the net profit was 34.03 million yuan, an increase of 38.98 million yuan over the same period of last year, with a year-on-year increase of 788.03%.

"In the first half of the year, the main reason for the growth of the company's main revenue is the rapid development of the civil product market, the expansion of horizontal and vertical application fields, the rapid expansion of carbon fiber precursor sales, and the reduction of cost; the main reason for the substantial increase in profits is that with the completion of product finalization, the large volume of tow products, and the steady increase of gross profit rate of main products." Jilin Carbon Valley said in the announcement.

It is also understood that Jilin Carbon Valley is currently under construction of an annual output of 40000 tons of carbon fiber precursor; Jilin Jinggong is expanding the production capacity of large tow carbon fiber.

In March this year, Shanghai Petrochemical also announced that it plans to invest 3.5 billion yuan to build a 48K large tow carbon fiber project with 24000 tons / year carbon fiber precursor and 12000 tons / year carbon fiber. The project will adopt self-developed technology to build two series of raw silk production lines, with a single series design capacity of 12000 tons / year, and six carbon fiber production lines with a capacity of 2000 tons / year for each production line.

"With the deepening of the application, large tow products are in short supply. The company's new project is to meet the domestic market demand for large tow carbon fiber and composite materials, and promote the company's carbon fiber technology progress. Next, the company will reduce costs, stabilize product quality and improve product profitability. " Shanghai Petrochemical said in the announcement.

At present, the "new carbon fiber production project" will be promoted in March 2019. On July 24 this year, Guangwei composite announced that its subsidiary Inner Mongolia Guangwei Carbon Fiber Co., Ltd. acquired the right to use a plot of land in Jiuyuan Industrial Park, Baotou, Inner Mongolia, with an area of about 420000 square meters.

As for the hot market of large tow, Lin Gang analyzed and pointed out: "an important goal for enterprises to choose large tow varieties is to pursue lower cost and large-scale industrial application. In the past ten years, the overall development of China's carbon fiber industry has basically followed the technical route of Japanese enterprises, and great achievements have been made in the preparation of small tow. However, for the preparation of large tow, from the perspective of system technology, China is still relatively lack of experience in a large number of equipment and engineering. Overall, at present, there is a strong demand for large tow in domestic and foreign markets. Therefore, China should strive to develop large tow carbon fiber preparation system technology. It should also be noted that the overall cost reduction and efficiency increase of the industry is very important, including the development of large tow with low cost and high performance. Of course, low-cost technology is actually a systematic project, and large tow is only one of the options. On the whole, speed increase (high speed) and beam lifting (tow) are both critical. "

"From a technical point of view, domestic large tow carbon fiber manufacturers have already possessed competitive advantages. Next, we need to work harder on cost control. In the case of large carbon fiber, the cost of domestic fiber is mainly driven by the cost Yan Bing said.