What are the common processes for composite spinning fibers
source:
wap.bjqljd.com.cn | Release time:2025-06-11
The common processes of composite spinning fibers are mainly designed based on the characteristics of raw materials and fiber structure requirements. The following introduces melt composite spinning, solution composite spinning, post-treatment fiber opening process, and other special processes, covering the process principles, characteristics, and applicable scenarios:
1、 Melt composite spinning process
1. Process principle
Two or more thermoplastic polymers (such as polyester, nylon, polypropylene, etc.) are melted separately and extruded simultaneously through composite spinning components (such as multi-layer spinnerets), and then combined into fibers during the cooling and forming process.
2. Core Features
Efficient and continuous: The polymer has good fluidity in the molten state and can achieve high-speed spinning (spinning speed up to 3000-6000 meters/minute), suitable for large-scale industrial production;
Temperature control key: It is necessary to match the melting temperature of each component (temperature difference is usually ≤ 10 ℃) to avoid overheating decomposition or uneven cooling of a certain component, which may cause delamination.
3. Typical applications
Parallel composite fibers: such as acrylic/polyester parallel fibers, which utilize the difference in shrinkage rate to produce curled elasticity;
Leather core composite fiber: such as wear-resistant fibers with polyester as the core and polyamide as the skin, or insulation fibers with a hollow core structure.
2、 Solution composite spinning process
1. Process principle
Dissolve two or more polymers in a solvent to form a spinning solution, which is then layered and extruded through a composite spinning component. Composite fibers are then formed through coagulation baths (such as wet spinning) or volatile solvents (such as dry spinning).
2. Core Features
Widely applicable materials: can be used for difficult to melt polymers (such as aramid, cellulose, polyvinyl alcohol, etc.), or systems that require the introduction of functional additives (such as antibacterial agents, conductive fillers);
High solvent recovery requirements: Wet spinning requires a large amount of solvent (such as N-methylpyrrolidone used in aramid production), which needs to be matched with environmentally friendly recovery equipment to reduce costs and pollution.
3. Typical applications
Island type composite fibers: such as PET (sea)/PA (island) system, formed by solution spinning to form island like structures, followed by dissolving the "sea" components to obtain ultrafine fibers;
Functional skin core fibers: such as polyvinyl alcohol fibers containing antibacterial agents (such as silver ions) in the skin layer, used for medical dressings.
3、 Post processing fiber opening process (for island type and orange petal type fibers)
1. Solvent dissolution method (main process for sea island fibers)
Principle: Treat composite fibers with specific solvents (such as toluene dissolving PET "sea" components or sodium hydroxide dissolving PA "sea" components) to separate the "island" components into ultrafine fibers.
Features: High fiber opening efficiency, controllable fiber fineness (up to 0.1 denier or less), but attention should be paid to solvent toxicity and recovery (such as closed operation for toluene).
2. Mechanical fiber opening method (commonly used process for orange petal fibers)
Principle: Through mechanical friction, stretching, or high-pressure water flow impact, the petals of the orange petal shaped composite fibers are separated to form ultrafine fiber bundles.
Features: No solvent required, good environmental friendliness, but the uniformity of fiber opening depends on equipment accuracy, suitable for scenarios with slightly lower fineness requirements (such as cleaning cloth fibers).
4、 Other special processes
1. Blending composite spinning process
Principle: First, blend two types of polymer melts or solutions, and then extrude them through spinning components to form a micro dispersed composite structure (such as a nano scale sea island structure).
Characteristics: The process is simple and suitable for preparing uniformly dispersed functional fibers (such as antibacterial fibers with added nanoparticles), but it is difficult to control the correct macroscopic composite structure (such as skin core, parallel).
2. Electrospinning composite process
Principle: High voltage electric field is used to spray polymer solution or melt into nanoscale fibers, which can simultaneously spray multiple solutions to form composite structures (such as medical fibers with drug core and sustained-release carrier skin).
Characteristics: The fiber diameter can reach the nanometer level (50-1000 nanometers), with a large specific surface area, suitable for preparing functional nanofiber membranes (such as filtration, wound dressings), but with low production efficiency, it is mostly used in laboratories or small batch production.
3. lotion composite spinning
Principle: two kinds of polymers are made into lotion, extruded through composite spinning components, and dried to form composite fibers (such as polyethylene/polypropylene lotion composite to improve flexibility).
Features: Suitable for water-based systems, good environmental friendliness, but low fiber strength, mostly used for non-woven fabrics or low strength functional materials.