Polypropylene staple Fiber
What is Polypropylene Staple Fiber?
Polypropylene staple fiber (PP fiber) is high-strength bundled monofilament fiber made from polypropylene. Polypropylene is the first stereoregular polymer to have achieved industrial importance. The fibres from polypropylene were introduced to the textile industry in the 1970s and in the following years they fast became an important addition in the rapidly growing market of synthetic fibres.
Today polypropylene is almost as popular and important as polyester, nylon and acrylic. Although its use in the market of household textiles has been rather limited, the bulk of the fibre produced is used for industrial applications. For example, if you add it to mortar or concrete, it will efficiently reduce micro-cracks, which were caused by solid plastic shrinkage, heat shrinkage and temperature changes.
Polypropylene (PP) is a thermoplastic. It is manufactured from propylene gas in presence of a catalyst such as titanium-chloride. Besides, PP is a by-product of oil refining processes.
Most polypropylene used is highly crystalline and geometrically regular, opposite to amorphous thermoplastics, such as polystyrene, PVC and polyamide, with randomly placed radicals. On the other hand, PP has higher working temperatures and tensile strength than polyethylene.
Polypropylene chips can be converted to fiber/filament by traditional melt spinning process, though the operating parameters need to be adjusted depending on the final products.
The manufacturers often use special equipment such as polypropylene staple fiber spinning machines and other specialized machinery. Although they can differ, depending on the manufacturer and the production line, some of the most important phases of the production process are the following:
- Metering – Molten polymer is metered through spinnerets with a number of holes to form filaments.
- Spinning – The spinning pack consists of three parts – filters, distributor which distributes the molten polymer over to die surface and the die.
- Quenching – The extruded filaments/fibers are solidified by air/water quenching: the cool air is distributed without damaging the filaments.
- Finishing – Improvement of the antistatic properties and reducing the abrasion.
- Hot Stretching – The fiber is stretched several times in a chemical hot bath for the enhancement of the physico-mechanical properties.
- Crimping – The fiber is then crimped to be made suitable for various spinning systems.
- Thermosetting – It is a treatment in hot air or steam that removes the internal stresses and relaxes fibers. The resultant fibers are heat-set with increased denier.
- Cutting – Fibers are cut into 20 to 120 mm length pieces, depending on the system they are intended for.
In this video you can see the exact process in the Rilon factory, the only PP staple fiber manufacturing company in Serbia, with all of the machinery, details and phases of the production.
Properties and Specifications
There are multiple important properties of the PP staple fibers, but probably the most significant for the industry is the fiber structure. Polypropylene fibers are composed of crystalline and non-crystalline regions. The spherulites developed from a nucleus can range in size from fractions of a micrometer to centimeters in diameter. Each crystal is surrounded by non-crystalline material.
When it comes to the crystallinity of the polypropylene staple fibre, the degree of crystallinity is generally between 50-65%, depending on processing conditions. Crystallization occurs between glass transition temperature and the equilibrium melting point. The crystallization rate of PP is fast at low temperature.
Physical properties of polypropylene fiber:
Rilon product range offers staple fiber fineness of: 6.6, 8.8, 10, 17, 70, 100, and 120 dtex, with the cutting length of 30, 45, 60, 70, 75, 90 and 150 mm.
- We offer a variety of colors and do custom toning, as per request.
- The tensile strength ranges from 2.2 to 4 cN/dtex
- Delivered in bales measuring 70 x 110 x 140.
- One bale weighs from 180 to 200 kg.
Thermal properties of polypropylene fiber:
Polypropylene fibers have a softening point in the region of 140°C and a melting point at 165°C. At temperatures of -70°C or lower, PP fibers retain excellent flexibility. At higher temperature, PP fibers nearly remain their normal mechanical properties. They have the lowest thermal conductivity of all commercial fibers. In this respect, it is the warmest fiber of all.
Rilon also manufactures staple fiber with UV stabilizers, in order to avoid the fibers becoming weathered by the direct or indirect impact of heat and ultraviolet light.
Applications: Different Types of Usage for Polypropylene Staple Fiber
Because polypropylene staple fibers are extremely chemical resistant and have a low molecular weight, they find their application in a wide range of quality product applications, and are ideal material for many uses.
PP staple fiber is available in fine, standard and coarse denier ranges. They offer high and superior high tenacity, so they find their application in various industries:
- Flooring Coverings
- Sports & Utility
- Technical Fibres
- Home & Commercial
Because of its superior quality and comparatively low price, polypropylene fiber finds extensive use in the nonwovens industry. Some of the main applications include: nonwoven fabrics, absorbent product markets (diapers), home furnishings and automotive industry. It is also used for woven carpets, non woven carpets, upholstery, spinning yarns, filer fabrics, thermal bonded fabrics, insulations, felts, building constructions…
They can also be used for EPP model aircrafts, since EPP foam is able to absorb kinetic impacts without breaking, retains its original shape, and exhibits memory form characteristics which allow it to return to its original shape in a short amount of time.
Main Benefits of Polypropylene Staple Fiber
Usage of polypropylene fibers has numerous advantages:
- PP is a light fiber and its density is the lowest of all synthetic fibers. Polypropylene staple fiber has low specific gravity, resulting into better relative coverage, high dimensional stability, excellent recovery properties like elasticity and resiliency, and low static charge.
- It does not absorb moisture. This means the wet and dry properties of the fiber are identical. Low moisture regain is not considered a disadvantage because it helps in quick transport of moisture, which is perfect for some special applications like ever-dry diapers for babies and adults.
- It has excellent chemical resistance. PP fibers are very resistant to most acids and alkalis.
- The thermal conductivity of PP fiber is lower than that of other fibers and may be used in applications as thermal wear.
Rilon – A Great Solution for the European PP Fiber Market
There are many polypropylene staple fiber manufacturers in the world, probably the majority of them being stationed in India and China, however, if you’re based in Europe, faster and financially better option would be to look for a geographically closer manufacturer.
Rilon is a factory based in Serbia, thus perfect for any customers interested in polypropylene staple fiber market from Southeastern Europe, but also from Europe in general, including Russia.
Rilon is a privately-owned manufacturer engaged in the production and sale of PP synthetic fibers, BCF filament, CF yarn and staple fibers with a wide range of decitex and colors, with or without UV stabilizers. All of our products are specifically designed to meet the customer needs and requirements.
For more information, do not hesitate to contact us.