In the microfiber production methods, direct spinning method is the simplest, but it is difficult to spin 0. 55 dtex below the fiber. Other methods, including meltblown and flash method, have greater limitations, meltblown method, although also simpler, but the fiber thickness and length is more difficult to control, and most of them are used in the immediate net, the production of non-woven base cloth. Flash method relies on the rapid evaporation of solvent into fiber, but also difficult to uniform and stable control of fiber quality. They are random ultra-fine fiber spinning method.
Two-component spinning method is currently the most applied and research methods, can be broadly divided into composite spinning and blended spinning two types, which is the most applied to the composite spinning method, according to the different requirements of fiber density of different production processes and stripping methods. Two-component fibers, also known as composite fibers or conjugate fibers, according to the different cross-sectional distribution, there are parallel type, skin core type, island type and so on.
In the parallel fiber in the two components along the length of the direction can be divided into two or more clear areas, the distribution of the two components of the area and shape of a great deal of variation, the shape of different; bicomponent fiber is another important species of skin-core type, in which the core component is completely wrapped by another component (skin), the two components of the cross-sectional shape and area are also different; bicomponent fibers also include island-type fibers, also known as the substrate The bicomponent fiber also includes the island type fiber, also known as the matrix – the original fiber type fiber.
Island fiber is a composite fiber spun by compounding or blending two thermodynamically incompatible polymers in a certain ratio, one of which is the disperse phase (i.e., off-component) and the other is the continuous phase (i.e., sea-component). The island component is contained in the sea component in the shape of very fine fibers, and the cross-section of the very fine fibers is island-shaped distribution, and its long axis is parallel to the composite fiber. According to the different distribution patterns of islands, there are two types of islands: fixed islands and indefinite islands.
The former island distribution is uniform and fixed, the latter is not fixed, but also not uniform, the thickness varies greatly, the finest than the fixed island type of fine, but thick can be more than 0.1dtex; The former is generally used in composite spinning method, the latter using co-mingled spinning method; The former can be spun filament, filament after cutting can also be made of various lengths of staple fiber, the latter can generally only be spun thick and thin and length of staple fiber. At present, the composite method of spinning more, because it can produce a variety of stable properties of ultra-fine fibers.
Sea and island two components have certain requirements, there are a variety of combinations.
Currently, PET or PA is the most popular choice for the island fraction, and cationic dye-dyeable polyester (COPET), PE, PA, PS, and PET are used for the sea fraction. The number of islands is usually 16, 36, 37, 51, 64, and it is now possible to produce microfiber with more than 100 islands. The former is mainly made into filament type for the production of various textiles, and the latter is mainly made into staple type for the production of synthetic leather base fabric.