Classification
Polypropylene fibers can be divided into long fibers, short fibers,
spunbond nonwovens, meltblown nonwovens, etc.
Polypropylene long fibers can be divided into ordinary long fibers
and fine denier long fibers (single fiber fineness ≤ 2.2 dtex,
which can be used to produce clothing and decoration and some
industrial filament products. Polypropylene fine denier long fibers
have good luster, soft touch, good drape and low density. They are
suitable for the knitting industry. When interwoven with cotton,
viscose, silk, spandex, etc. into cotton-covered polypropylene and
silk-covered polypropylene products, they are ideal materials for
making high-end sportswear, T-shirts, etc.
The production process of polypropylene staple fibers mostly adopts
a porous, low-speed, continuous process, that is, a short spinning
process. Polypropylene staple fibers are blended with cotton to
make polypropylene-cotton fine cloth and sheets, that is, fibers
blended with viscose can be made into blankets, polypropylene pure
spinning and blended wool yarn, polypropylene blankets, carpets,
polypropylene cotton cigarette filters. The thickness of fibers for
sanitary products is 1.5-2.5dtex, while the thickness of fibers for
floor fabrics is 5-10 dtex. The fiber length is 1.5-200.0 mm,
depending on the purpose of the fiber. The length of short fibers
used for concrete is 1.5-200.0 mm, the length used for diapers is
generally 40.0 mm, and the length used for floor fabrics is 60.0
mm.
Spunbond non-woven fabrics, also known as filament non-woven
fabrics, are made by melting polypropylene raw materials and then
extruding, spinning, stretching, laying nets, and bonding. It has
the characteristics of short process, low cost, high productivity,
excellent product performance, and wide range of uses.
Polypropylene non-woven fabrics are widely used in various fields
of production and life (such as disposable medical and sanitary
products, disposable anti-fouling clothing, agricultural fabrics,
furniture fabrics, linings for the shoe industry, etc.).
The fibers produced by meltblown non-woven fabric technology are
very fine (up to 0.25μm). Meltblown fabrics have a large specific
surface area, small pores and high porosity, so their application
characteristics such as filtration, shielding and oil absorption
are difficult to obtain by non-woven fabrics produced by other
separate processes. Meltblown non-woven fabrics are widely used in
medical and health care, thermal insulation materials, filtration
materials and other fields
Performance characteristics
(1) Lightweight
The density of polypropylene fiber is 0.90-0.92 g/cm3, which is the
lightest among all chemical fibers. It is 20% lighter than nylon,
30% lighter than polyester, and 40% lighter than viscose fiber.
Therefore, it is very suitable for filling winter clothing or
fabrics for ski suits, mountaineering suits, etc.
(2) High strength, good elasticity, wear resistance and corrosion
resistance
Polypropylene fiber has high strength (same in dry and wet states)
and is an ideal material for making fishing nets and cables; it has
good wear resistance and resilience, and its strength is similar to
that of polyester and nylon. Its rebound rate is comparable to that
of nylon and wool, and is much greater than that of polyester and
viscose fibers; polypropylene fiber has poor dimensional stability,
is easy to pill and deform, is anti-microbial, and is not
moth-eaten; its chemical resistance is better than that of general
fibers.
(3) It has electrical insulation and warmth retention
Polypropylene fiber has a high resistivity (7×1019Ω.cm) and a low
thermal conductivity. Compared with other chemical fibers,
polypropylene fiber has the best electrical insulation and warmth
retention, but it is prone to static electricity during processing.
(4) Poor heat resistance and aging resistance
Polypropylene fiber has a low melting point (165~173℃) and poor
stability to light and heat. Therefore, polypropylene fiber has
poor heat resistance and aging resistance and is not resistant to
ironing. However, its anti-aging performance can be improved by
adding anti-aging agents during spinning.
(5) Poor hygroscopicity and dyeability
Polypropylene fiber has the worst hygroscopicity and dyeability
among chemical fibers. It absorbs almost no moisture and its
moisture regain is less than 0.03%. Fine denier polypropylene fiber
has a strong wicking effect, and water vapor can be removed through
the capillaries in the fiber. After being made into clothing, the
clothing is more comfortable, especially ultra-fine polypropylene
fiber. Due to the increased surface area, it can transfer sweat
faster and keep the skin comfortable. Because the fiber does not
absorb moisture and has a small shrinkage rate, polypropylene
fabrics are easy to wash and dry quickly.
Polypropylene fiber has poor dyeability, light color, and poor
dyeing fastness. Ordinary fuels cannot dye it. Most colored
polypropylene fibers are produced by pre-spinning coloring. The raw
material can be dyed by solution, modified by fiber, and mixed with
fuel complexing agent before melt spinning.
