Research And Development Of Microfiber

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Guest: Professor Dai Lixing, Department of materials and chemical engineering, Soochow University

As an independent research and development project in the new material field of our country, the research and development of the key technology application and industrialization of shrinkage controlled copolyester full stretch yarn direct spinning superfine technology, led by Professor Dai Lixing of Soochow University and Jiangsu Xinmin textile Polytron Technologies Inc, has made China's research in the field of fine chemical fiber technology take a new step.

Dai Lixing said that the fine and luxurious fabric of ultra-fine fiber has long been the focus of the global textile industry, and the direct spinning method is a new technology for energy saving, emission reduction, low cost and high quality microfiber manufacturing.

Polyester fiber with different shrinkage is an important part of differential synthetic fibers, and is also one of the ideal raw materials for weaving high-grade fabrics. Shrinkage rate of shrinkage polyester fibers produced by physical method will drop after a period of time, so chemical shrinkage is the effective way to obtain stable shrinkage.

Direct spinning process is simple and low cost.

Compere: the application field of multi-functional composite fiber is more and more extensive. The research of microfiber has always been the concern of the industry. What is the overall situation of shrinkage controlled CO polyester full stretch yarn direct spinning superfining project?

Dai Lixing: the raw material of shrinkage controlled copolyester full stretch yarn direct spinning superfining project is terephthalic acid and ethylene glycol as the basic component, and the four component copolyester of two benzene and polyethylene glycol as copolymers.

It is very difficult to directly form microfiber on the conventional FDY spinning machine through micro holes. This project uses a rectifier to regulate the CV value of fiber shrinkage rate, stabilize the shrinkage of fibers, adopt three heat rollers to stretch, precisely control the spinning process, and so on, with the least amount of input to produce shrinkable controllable polyester (FDY) microfiber, so that the total fineness reaches 20dtex~30dtex, or the Microfiber with single filament size 0.3dtex~0.5dtex, the shrinkage rate can be adjusted between 15%~70%.

Moderator: domestic and foreign enterprises have been exploring how to prepare ultrafine fibers better than conventional spinning methods. What are the advantages of direct spinning?

Dai Lixing: shrinkage of fiber is an important function that affects the wearability and style of fiber. Different shrinkage has very different characteristics and application fields, so the production of shrinkage controllable superfine fiber has important practical significance.

The direct spinning method for preparing superfine drawing wires is to form microfiber directly through micro holes on the conventional FDY spinning machine. The process is simple, the production cost is low, energy saving and environmental protection. However, the spinnability of producing microfiber in direct spinning, the cooling technology in melt spinning, and the breakage of fibers and the prevention of filaments are the difficulties of production control.

Compared with the composite superfine wire, the direct method of producing ultra-fine silk technology wastes less 300kg tons per ton of silk and saves 5100 yuan per ton. There is no need to dissolve the solvent of the substrate, with less than 40 tons of solvent per ton, of which 39.2 tons of water is saved and 0.8 tons of sodium hydroxide is saved.

It can also be used in combination with other fibers, such as wool and silk, which are not solvent resistant or alkali. This is unmatched by the combination method.

Therefore, as one of the production methods of microfiber, direct spinning will continue to be developed and promoted on the basis of continuous progress in technology.

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Three innovations to achieve controllable shrinkage and ultra fining of fibers

Moderator: compared with the existing technology, what are the main innovations of the project?

Dai Lixing: our project has innovating the existing technology in three aspects.

First of all, a flexible and adjustable rectifier is designed. On the production line of polyester fine denier yarn, in order to reduce the internal stress of wire in the drawing process, and delay the development of the two structure of the primary wire, and stabilize the technology, a heating insulation zone commonly called slow cooling device is installed below the spinning component.

Since the specifications and installation of the retarder are fixed, the slow cooling effect of the primary wire can only be controlled by adjusting the temperature of the retarder.

Although the retarder can spin successfully in a wide temperature range, the temperature has a significant effect on the microstructure of the fiber, resulting in adverse effects on the properties and quality of the finished fiber.

Based on model prediction and experimental data, a new rectifier is designed to replace the retarder. Compared with the retarder, the wind blown by the side blowing device acts vertically and vertically on the tow under the action of the rectifier, while preventing the side blowing directly blowing to the spinneret surface, so that the shrinkage property of the primary fiber can be stabilized. At the same time, the rectifier is convenient for installation, disassembly and electricity saving, and is especially suitable for producing ultra-fine polyester fibers with a total 20dtex~30dtex of size or below 0.5dtex of monofilament.

Second, shrinkage control of microfiber: shrinkage of polyester fibers after physical treatment will be reduced after a period of time. Therefore, chemical methods must be adopted to achieve stable shrinkage.

We use the copolymerization method as the main means to regulate the shrinkage of fiber. According to the mechanism of contraction, we control the amorphous and crystalline regions by adding the amount of second monomers (IPA) to regulate the degree of fiber contraction.

Through systematic study, the corresponding relationship between IPA and shrinkage rate is obtained.

In addition, when the flexible chain PEG enters the macromolecular backbone, it reduces the technical barriers to overcome when forming the folded chain, which is conducive to the production of microcrystals. The size of the obtained polycrystalline polyester is obviously increased, which is conducive to the dyeing modification of the fibers, and because of the decrease of the glass pition temperature, the stretching becomes easier and the filaments are reduced during the drawing process.

Finally, the process control of direct spinning ultra-fine FDY fiber is carried out: the winding speed of FDY is as high as 5000m/min, while the total denier of fiber products is small, only the total denier 20dtex~30dtex, or the monofilament size is less than 0.5dtex. It is very difficult to spray out the filament directly from the spinneret, and the raw material is not conventional polyester and 20 high-speed spinning equipment.

In addition to precisely controlling the spinning temperature, spinning speed and blowing conditions, the conventional drafting is changed to three hot rollers, two drafting, which makes the thermal stretching and finalization more complete and stable, which can improve the uniformity and shrinkage stability of the fibers.

New means of manufacturing high-grade fabrics by technology industrialization

Moderator: after more than three years of research and development practice, so far, what is the application of the project? What economic and social benefits will it bring?

Dai Lixing: our country has been using composite spinning to produce ultrafine fibers, but its technology is complex, high cost and easy to produce environmental problems. On the conventional FDY equipment, we have made proper remolding, and made direct spinning of microfiber and controlled shrinkage.

Take the investment of 20 million yuan as an example, from 2008 to 2010, the new profit of the project reached 52 million 812 thousand yuan, an increase of 13 million 135 thousand and 500 yuan compared with the previous year, and the new tax revenue was 17 million 613 thousand and 800 yuan.

Shrinkage polyester copolyester full stretch yarn direct spinning is a promising technology.

First, the advantages and unique and excellent properties of the direct spinning of microfiber as mentioned previously; two, because of the different degree of thermal shrinkage of copolyester fibers, different styles and properties of products can be obtained.

For example, the fibers with heat shrinkage of 15%~25% can be used to weave all kinds of crepe, concave convex fabric and jacquard fabric; the heat shrinkable 15%~40% fiber can be used for bulky wool, blankets, artificial fur, etc. the fiber with heat shrinkage of 40%~70% can be used for synthetic leather, artificial suede and so on.

The shrinkable fibers made from chemical modification of polyester fibers are highly favored due to their high boiling water shrinkage and stable shrinkage. They are especially suitable for composite with Sea Island fibers for the production of high grade suede fabric, peach skin and high density fabric.

Therefore, the combination of controlled shrinkage and ultrafine technology is a new way to produce high-grade fabrics.

User evaluation

Shrinkage polyester copolyester full stretch yarn direct spinning superfine technology, single filament size and total tow size are very small, technical difficulty and high fiber style.

The technology has been applied by our company, which has good fiber forming quality, stable fiber quality, high quality products, easy shrinkage of fiber, mature technology, low cost, energy saving and emission reduction. It has brought us good economic and social benefits.

It is hoped that further development of other functional ultra fine wires will be further developed in the future to expand application areas.