48K Big Tow Carbon Fiber Technology Is Very Difficult. Why Can Jilin Chemical Fiber Nibble Down This "Hard Bone"?

For Japan and the United States.

For large powers, the manufacturing technology of large wire bundles carbon fiber is one of the key technologies to achieve low cost in the carbon fiber industry.

In order to further enhance the competitiveness of China's carbon fiber industry, tow is an important development direction. Therefore, tow has become the focus of attention in China's market in recent years.

However, because of the difficulty of preparation technology, big tow becomes a "hard nut to crack", which makes many domestic carbon fiber enterprises look awed.

However, this situation is being broken through by leading enterprises step by step.

Recently, from the Jilin chemical fiber group (hereinafter referred to as "Jilin chemical fiber") news, the company independently developed 48K large tow carbon fiber precursor through carbonization and continuous mass production, and the carbonization effect far exceeded expectations, all indicators exceeded the level of T300 products, becoming a new carbon fiber product after the success of 24K carbon fiber market.

Well,

What new breakthroughs have been made in tow?

What are the difficulties in preparation technology and what are their future market prospects?

1K in the production of carbon fiber refers to a carbon fiber precursor containing 1000 monofilaments.

According to the industry standard, the carbon fibers in each bundle of carbon fibers whose fibers are less than 24K, such as 1K and 3k, belong to small tow carbon fibers, and the carbon fibers in each bundle of carbon fibers are larger than or equal to 24K.

Compared with small tow, the production efficiency of large wire bundle carbon fiber is higher.

During the preparation process, the laying efficiency is higher, and the production cost can be reduced by more than 30%.

From the international market, the large wire bundle carbon fiber is mainly used in wind power blades, energy buildings and other industrial markets.

The carbonized 48K carbon fiber precursor of Jilin chemical fiber refers to the original filament containing 48000 monofilaments, which belong to big tow.

The biggest advantage of 48K tow carbon fiber is that under the same production conditions, the single line productivity of carbon fiber can be greatly increased, and the low cost of production will be realized. This will help to break the application limitation of carbon fiber due to higher price and lay the foundation for further expanding the application market of carbon fiber reinforced plastics.

Since July 2017, Jilin chemical fiber has studied the 48K large tow carbon fiber precursor, drawing on the experience of 24K carbon fiber precursor production, reconstructing the raw liquid process and upgrading the key equipment technology.

In July this year, the company successfully developed the polymerization and spinning technology of 48K carbon fiber precursor, and formed a kiloton PAN based 48K carbon fiber precursor technology package, and batch produced the 48K carbon fiber precursor.

From product launch to quality stability, Jilin chemical fiber research and development team has conquered the difficulties of linear density control, uneven washing effect and unstable raw silk strength.

In fact, at the end of last year, the 2000 ton production line of the 8000 ton tow carbon fiber carbonization project of Jilin chemical fiber has been successfully tested, and then achieved stable operation, marking the important step of China's large tow carbon fiber production technology, which laid a solid foundation for the successful carbonization of 48K large wire strand carbon fiber precursor.

Its overall 8000 ton tow carbon fiber carbonization project is expected to be completed by the end of next year.

After the 48K raw silk was produced in Jilin chemical fiber, the oxidation and carbonization test was carried out for the first time to the 2000 ton / year carbonization production line, and the joint research on the upstream and downstream was carried out. From the pilot test, the pilot test to the batch carbonization, and repeated adjustment and verification, the 100 48K carbon fiber precursor was successfully carbonized.

According to the test, the tensile strength, tensile modulus and interlaminar shear strength of 48K large tow carbon fiber can meet the needs of application.

At this point, Jilin chemical fiber produced the first batch of 48K large tow carbon fibers in the true sense.

Achieving mass production of 48K tow carbon fiber is of great significance.

The industry pointed out that only by constantly tackling carbon fiber preparation technology, persisting in independent innovation, continuously improving the industrialization level of China's carbon fiber, and continuously promoting low cost can China's carbon fiber be more widely applied to wind turbine blades, oil fields, atmospheric and high voltage capacity, rail pportation and other industrial fields, thus providing a solid guarantee for China's manufacturing to grow from strength to strength.

The technical difficulties of big tow are systematic.

Some agencies predict that the annual demand growth of tow carbon fiber will exceed 16% in the next few years. By 2020, the demand for tow carbon fiber will reach 150 thousand tons in the global market, and the demand for the Chinese market will reach 77 thousand tons.

Song Dewu, chairman of Jilin chemical fiber group company, said that in the past decades, the development and growth of the international carbon fiber industry was mainly promoted by the leading enterprises such as Japan and Dongli, as well as the downstream application enterprises such as Boeing and Airbus. The aerospace industry has also been the main application market of carbon fiber.

Under this technical system, the main technology of carbon fiber preparation is small tow and high intensity route.

The rapid development of China's carbon fiber industry in recent 10 years is mainly based on this idea.

But at this stage of development, the growth of the tow carbon fiber application market is slowing down. Therefore, in the past few years, Jilin chemical fiber has striving towards the direction of "low cost, big tow, versatile and high quality" on the basis of maintaining the existing industry of the tow carbon fiber precursor production.

However, tow technology is like a hard nut to crack. Enterprises can not chew easily without loosening it.

It is understood that there are still few enterprises that can produce large strand of carbon fiber precursors in China, and there are few truly marketable ones.

The raw silk technology is divided into wet two step process and DMSO (dry spray wet process) process, and Jilin chemical fiber is wet two step method.

What are the difficult aspects of the preparation technology of large filament carbon fiber?

The first difficulty is that there is no clear standard and sound system for the production of large tow carbon fiber. This has greatly increased its R & D. Compared with small tow, the preparation technology of large strand carbon fiber is more difficult in many links such as raw silk, polymerization, pre oxidation and carbonization.

For example, if we produce 1K and 3K small tow carbon fibers, there will be 1000 or 3000 holes on a spinneret, but if we produce 48K large tow carbon fiber and 48000 holes on a spinneret, this will be challenging in itself.

The difficulty two is the stability of the CV value.

If it is the production of 3K small tow carbon fiber, it is relatively easy to request the uniformity of each thread sprayed out of 3000 holes on a spinneret. This is relatively easy; but if it is to produce 48K tow carbon fiber, it is required that the uniformity of each wire sprayed out of 48000 holes on the spinneret is the same, the base number is several times larger, and the difficulty is quite large.

The three difficulty is the problem of wool. The problem of wool is always accompanied by the spinning process. What enterprises need to do is to control the proportion of wool in a reasonable range.

If carbon fiber is used to produce 1K, 10 wool will be produced according to the ratio of 1% wool, which does not seem obvious; but if 48K carbon fiber is produced, there will be more than 400 filaments in the same proportion of wool, which will make the wool look more obvious.

Therefore, how to control the filament ratio of large tow carbon fiber is a big problem. At present, there is no such standard in the world.

The difficulty four is the carbonization link. After the production of large strand of carbon fiber precursor, there will be many new challenges in the carbonization link.

For example, the problem of fuzz may not be obvious on the raw silk, but it may be highlighted in the carbonization link, because there will be severe chemical reactions in the carbonization link, which may lead to some key breakage phenomena in the molecular structure of the fiber.

To solve these problems, enterprises need to work hard in terms of the proportion of monomer, the improvement of technological formula, and the exploration and perfection of every production link.

It can be found that the preparation technology of large tow is a complex system engineering.

To solve these problems, it means that enterprises must continuously carry out technological tackling. This is usually a long-term process of difficulty, devotion and effectiveness, and also tests the comprehensive level of enterprises in terms of capital, technology, talents and equipment.

It is commendable that Jilin chemical fiber has been conquering technical difficulties in recent years, and has gradually chewed down the "hard bone" of big tow, and has gradually gained market recognition.

Reporters learned that 1~7 months this year, Jilin chemical fiber carbon fiber precursor sales volume of 3834 tons, an increase of 102% over the same period, the main reason is that 24K and 25K carbon fiber precursor sales are good.