Introduction to the use of ultra-short fiber
Ultra-short fibers generally refer to any short fibers with a cut length of less than 20mm. The specifications of these products require a variety of fiber forms and cut lengths. As far as I know, its application scope is the enhancement of plastic materials such as hygiene products, non-woven products, papermaking, paint and concrete. As far as PET products are concerned, they are mainly used for papermaking and the reinforcement of asphalt materials. Generally, the single filament denier range of fiber is about 6 denier, and the low ones can reach 0.5 denier. The applications are as follows:
3-6mm: Generally used for papermaking, sanitary products, medical products, etc.
6-20mm: General auto parts (such as battery filter paper), filter materials, plastic material (asphalt) reinforcement, non-woven products, etc.
The most important quality of ultra-short fiber products is the uniformity and accuracy of the cut length of the fiber. This is easy to understand. If the length of 38mm is cut, the length of 39mm may be normal, but 3mm and 4mm are two varieties. But if it is an ultra-short fiber used for reinforcing materials, in addition to the accuracy of the cut length, dispersion is the most important indicator. But the dispersibility is generally ensured by adding a dispersant. Therefore, as the equipment for producing ultra-short fibers, the most critical is the cutting equipment and the tension control system. In addition, packaging should consider the requirements of sealing (because ultra-short fibers are like dust). Other technical issues should be resolved smoothly.
1. Application fields of polypropylene (PP) ultra-short fiber:
1. Engineering fiber:
Mainly used to improve the impermeability and crack resistance of mortar and concrete. This kind of ultra-short fiber is characterized by small diameter, generally without crimp, and relatively high requirements for dispersibility. Generally, special fiber surface treatment technology (such as three-lobe type, etc.) is used to improve the physical contact between the fiber and concrete. force. At present, there are more domestic manufacturers of this ultra-short fiber, mainly because the product has relatively low requirements for the accuracy of the cutting length, and the investment in equipment is relatively small, so that the quality of the product is uneven.
The general performance indicators of engineering fibers are as follows:
Density: 0.91
Length: 3mm, 6mm, 10mm, 12mm, 15mm, 20mm
Elastic modulus: >3500MPa
Tensile strength: >400MPa
Anti-acid and alkali: strong
Packing form: bagged
General dosage: average 0.9 kg/m3 concrete
Because polypropylene fiber itself has the characteristics of non-water absorption, strong acid and alkali resistance and elastic modulus equivalent to that of concrete, it can greatly improve the impermeability, abrasion resistance, crack resistance, impact and fatigue resistance of concrete after adding. . It has been widely promoted in developed countries abroad, and can be used in projects with special construction methods such as concrete pavements, bridge decks, airport pavements, rivers, dams, reservoirs, tunnels and mine walls, and can extend the service life of the project.
2. Paper fiber:
Paper fiber is divided into dry papermaking and wet papermaking. Generally, polypropylene fiber is mainly used in the field of dry papermaking, that is, puffed soft paper. Puffed soft paper is a new type of disposable sanitary material, which can be made into high-density dust-free paper absorbent core material, which is used to meet the special needs of high absorption capacity and improve the liquid holding effect. It can also be made into a low-density absorbent core material for medical materials. The polypropylene fiber used in dry papermaking is a sheath-core composite fiber, the surface layer is made of low melting point material, and the core layer is made of PP or other materials. In dry papermaking, a certain temperature is used to melt the low-melting skin layer, thereby uniformly bonding with wood pulp fibers and other water-absorbing materials to form a base material. The ultra-short fiber is characterized by a two-component structure, with less crimp or no crimp, and high antistatic and dispersibility requirements.
This product is mainly used in disposable medical appliances (mattresses, surgical gowns, dressings, etc.), sanitary napkins and changing pads, cosmetic paper, high-end household daily necessities, etc. According to overseas information, the consumption of expanded soft paper in the United States alone is nearly 1 million tons per year, and it is increasing every year.
In terms of wet papermaking, polypropylene ultra-short fibers are mainly mixed with other fibers to make paper with wet strength requirements, such as filter paper and tea bag paper.
3. Non-woven fabric fiber:
In the past, most of the fibers for non-woven fabrics were conventional fiber products. However, with the special requirements of automobile interior decorations, non-woven fibers are also required to be ultra-short fibers with a length of less than 20mm. The ultra-short fiber is characterized by low strength, high elongation, and a length generally above 6mm-20mm, without crimp or with small crimp. This product is mainly used in automotive interior materials, but also in the manufacture of other substrates such as furniture decoration. At present, ultra-short fibers and fibers such as polyester, viscose or polyamide/wood pulp have been mixed in proportion to be used in industrial wipes such as floor cloths and automotive polishing cloths to improve their wear resistance.
2. Application fields of polyester (PET) ultra-short fibers:
1. Paper fiber:
Polyester ultra-short fiber is mainly used in the wet papermaking industry. This type of ultra-short fiber is characterized by good antistatic and dispersibility, good hydrophilicity, high strength, good toughness, low heat shrinkage, and generally no curling , The length range is 3mm-12mm. Using this kind of polyester ultra-short fiber and plant fiber to make paper by interaction can enhance the strength of the paper, improve the performance of the paper, and expand its use. It can be used to make recycled paper, filter paper, anti-counterfeiting tickets and other special papers.
2. Engineering fiber:
Due to its higher melting point, polyester ultra-short fiber is mainly used for crack resistance and reinforcement of high-grade highway asphalt. The general performance indicators are as follows:
Length: 4mm-20mm
Specific gravity: 1.36/g.cm-3
Melting point: >250 degrees
Breaking strength: >700MPa
Elongation at break: 18-35%
Curl degree: none
After adding polyester ultra-short fibers, the thermal stability, hydrophobicity and fatigue resistance of the asphalt pavement can be greatly enhanced, greatly extending the service life of the expressway and reducing maintenance costs.
After adding polyester ultra-short fibers, the thermal stability, hydrophobicity and fatigue resistance of the asphalt pavement can be greatly enhanced, greatly extending the service life of the expressway and reducing maintenance costs.
3. Other industrial uses:
Polyester ultra-short fibers can also be used in the manufacture of industrial battery plates and separators, paint fillers for ships and ships, and can be used for flocking and replacing asbestos as building reinforcement materials and other purposes.