Pet Spunbonded Production Line: Full-process technical decoding from raw materials to finished products

I. Introduction
In the field of non-woven fabric production, PET (polyethylene terephthalate) spunbond production line occupies an important position with its unique advantages. With the continuous advancement of science and technology and the diversified development of market demand, the technology of PET spunbond production line is also continuously innovating. It uses polyester chips as the main raw material and transforms the raw materials into spunbond non-woven fabrics with excellent performance through a series of precise and efficient process flows. This non-woven fabric has the characteristics of high strength, good weather resistance, excellent chemical stability and excellent dimensional stability. It is widely used in many fields such as medical and health, agriculture, construction, packaging, and automotive industry, and has become an indispensable basic material in modern industry.
II. Process flow of Pet Spunbonded Production Line
2.1 Raw material preparation
Raw material selection: The main raw material of PET spunbond production line is polyester chips. The quality of polyester chips has a significant impact on the performance of the final product, and its characteristics need to be strictly controlled. For example, the intrinsic viscosity is generally 0.64-0.68dL/g, which can ensure that the melt has appropriate fluidity and spinnability in subsequent processing; the content of diethylene glycol is controlled at 1.0%-1.5%, which can effectively avoid the problems of decreased thermal stability and color deterioration of fibers caused by excessive diethylene glycol content; the melting point is usually 255-265℃, ensuring melt processing at the appropriate temperature.
Chip drying: Since polyester chips are easy to absorb moisture during storage and transportation, the presence of moisture will cause polyester hydrolysis when melted at high temperature, reduce molecular weight, and seriously affect fiber quality, so the drying process is crucial. Use a vacuum drum dryer or continuous drying equipment for drying to reduce the moisture content of the chips to below 50ppm. For example, in a continuous drying equipment, the chips are synergistically acted with hot air circulation and vacuum system at a temperature of 160-180℃ to achieve efficient and deep drying, meeting the stringent requirements of the spinning process for the moisture content of raw materials.
2.2 Melt extrusion
Working principle of screw extruder: The dried polyester chips are evenly fed into the screw extruder by the feeding system. The screw extruder consists of key components such as screw, barrel, heating device, transmission system, etc. The screw rotates at high speed in the barrel to push the chips forward. In this process, the chips are sheared and compressed by the screw and the heat provided by the external heating device of the barrel, and gradually melt. Different sections of the screw, such as the feeding section, compression section, and metering section, are designed with specific threads and parameters to achieve gradual compaction, melting and homogenization of the chips.
Temperature and pressure control: Accurate control of the temperature and pressure of each area of ​​the screw extruder is the key to ensuring stable melt quality. Generally speaking, from the feeding section to the metering section, the temperature gradually increases. The feeding section temperature is controlled at 220-240℃, so that the chips begin to soften; the compression section temperature is increased to 250-270℃, which promotes further melting of the chips; the metering section temperature is maintained at 270-290℃, ensuring that the melt has a uniform temperature and good fluidity. In terms of pressure, the pressure in the metering section is usually controlled at 10-20MPa. Stable pressure helps the melt to extrude at a constant rate, ensuring the continuity and stability of the spinning process. Through advanced automatic control systems, real-time monitoring and precise adjustment of temperature and pressure parameters ensure stable operation of the extrusion process.
2.3 Spinning Forming
Spinning box and spinneret: The molten PET melt is transported to the spinning box through the melt pipe. The spinning box is equipped with an independent heating and insulation system to ensure that the temperature of the melt is constant during the transportation and distribution process. The melt is evenly distributed to each spinneret through the distribution pipe in the spinning box. The spinneret is the core component of spinning forming, and the diameter, shape and distribution of its micropores play a decisive role in the specifications and quality of the fiber. The common spinneret micropore diameter is 0.2-0.4mm. According to the requirements of different fiber fineness, the micropore shapes are round, trilobal, and special-shaped. Different shapes give the fiber unique properties. For example, special-shaped fibers can improve the cohesion between fibers and the coverage of the fabric.
Spinning process parameters: Spinning speed is one of the key process parameters, usually 3000-6000m/min. A higher spinning speed can make the fiber form a more regular orientation structure during the stretching process, thereby improving the fiber strength. The cooling air temperature, wind speed and humidity have a significant impact on the fiber cooling and curing process. The cooling air temperature is generally controlled at 18-25℃, the wind speed is 0.4-0.8m/s, and the humidity is maintained at 60%-70%. Appropriate cooling conditions can ensure uniform cooling of the fiber and avoid problems such as uneven fiber thickness and hairy fibers caused by uneven cooling.
2.4 Drafting
Airflow drafting principle: The primary fiber stream extruded from the spinneret is stretched by the high-speed hot air flow in the spinning tunnel. The hot air flow velocity is much higher than the fiber stream velocity. Under the friction between the two, the fiber stream is rapidly stretched and thinned. This drafting method can effectively improve the orientation and crystallinity of the fiber, thereby improving the fiber strength and other properties.
Drafting multiple and process optimization: The drafting multiple is generally 5-10 times, and needs to be precisely adjusted according to product requirements and raw material characteristics. If the drafting multiple is too low, the fiber strength is insufficient; if the drafting multiple is too high, it is easy to cause fiber breakage. By optimizing the temperature and speed distribution of the drafting hot air flow and the structural design of the spinning tunnel, a more uniform and efficient drafting process can be achieved. For example, by adopting multi-stage drafting technology, different degrees of drafting force are applied to the fiber at different stages, gradually refining the fiber and improving its internal structure, thereby improving the stability and consistency of product quality.
2.5 Web forming
Web laying method: The fiber bundles after drafting are evenly laid on the web curtain to form a fiber web. Common web laying methods include mechanical web laying and airflow web laying. Mechanical web laying uses a mechanical device to evenly distribute the fibers on the web curtain, which is suitable for products with high requirements for web uniformity; airflow web laying uses airflow to guide the fibers to deposit on the web curtain, which can achieve high-speed production and good web uniformity. In actual production, the appropriate web laying method can be selected according to product requirements, or a combination of the two methods can be used to further improve the quality of the fiber web.
Web quality control: The quality indicators such as the uniformity, weight deviation and fiber arrangement direction of the fiber web have a significant impact on the performance of the final product. By optimizing the parameter settings of the web forming equipment, such as the web laying speed and angle during mechanical web laying, the air flow speed and flow distribution during airflow web laying, and adopting an advanced online detection system, the weight and uniformity of the fiber web can be monitored in real time. When deviations occur, the equipment parameters can be adjusted in time to ensure that the quality of the fiber web is stable within the standard range.
2.6 Reinforcement
Hot rolling reinforcement: Hot rolling is a common reinforcement method for PET spunbond nonwovens. The fiber web passes between a pair of heated rollers. The temperature and pressure on the surface of the rollers cause the fibers to melt and adhere at the contact points, thereby giving the fiber web a certain strength and stability. The upper roller is usually an engraved roller, and the lower roller is a smooth roller. The patterned roller can form a specific pattern on the cloth surface to increase the aesthetics and functionality of the product, such as improving the air permeability and anti-slip properties of the fabric. The hot rolling temperature is generally 180-230℃, and the pressure is 0.3-0.8MPa, which needs to be precisely adjusted according to the fiber type, fiber mesh weight and product requirements.
Other reinforcement methods: In addition to hot rolling reinforcement, needle punching reinforcement, hydroentanglement reinforcement and other methods can be used for PET spunbond nonwovens. Needle punching reinforcement uses needles to repeatedly puncture the fiber mesh to make the fibers entangled with each other to achieve reinforcement. It is suitable for the production of geotextiles, filter materials and other products with high strength requirements; hydroentanglement reinforcement uses high-pressure water flow to impact the fiber mesh to make the fibers entangled with each other. The products produced are soft to the touch and high in strength. They are often used in medical and health, wipes and other fields. Different reinforcement methods have their own characteristics and can be flexibly selected according to product use and performance requirements.
2.7 Winding and slitting
Winding equipment and process: The reinforced PET spunbond nonwoven fabric is wound into a cloth roll by a winder. The winding machine is equipped with a high-precision tension control system to ensure that the tension of the cloth surface is stable during the winding process, avoiding problems such as uneven tightness and uneven surface of the cloth roll caused by uneven tension. The winding speed matches the speed of the production line, generally 10-150m/min, and can be adjusted according to production needs. At the same time, by controlling the winding pressure and roll diameter, the cloth roll is guaranteed to have good molding quality and winding density.
Slitting process and quality control: According to market demand, the large cloth roll is cut into small cloth rolls of different widths by the slitting machine. The slitting machine uses high-precision knives and positioning systems to ensure that the slitting size accuracy is controlled within ±1mm. During the slitting process, the cloth surface quality is monitored in real time to prevent problems such as uneven cutting edges and scratches. After the slitting, the small cloth rolls can be put on the market for sale after quality inspection and packaging.
III. Core equipment of Pet Spunbonded Production Line
3.1 Screw extruder
Screw structure and material: As the core component of the screw extruder, the screw structure design directly affects the melting effect and melt quality of the slices. The screw usually adopts a gradual or sudden change structure. The gradual change screw is suitable for processing materials whose viscosity is sensitive to temperature, while the sudden change screw is more suitable for processing polyester chips whose viscosity is sensitive to shear rate. The screw material is made of high-strength, wear-resistant and corrosion-resistant alloy steel, such as 38CrMoAlA. After nitriding treatment, the surface hardness can reach HV950-1200, which effectively improves the service life and working stability of the screw.
Drive and control system: The drive system of the screw extruder generally adopts an AC variable frequency motor. The motor speed is accurately adjusted by the inverter to achieve precise control of the screw speed, so as to flexibly adjust the extrusion volume. The control system is equipped with advanced temperature and pressure sensors to collect temperature and pressure data of each area of ​​the screw in real time and transmit the data to the PLC (programmable logic controller). The PLC automatically adjusts the power of the heating device and the flow of the cooling system according to the preset process parameters to ensure that the screw extruder runs stably in the best working state.
3.2 Spinning box
Melt distribution system: The melt distribution system inside the spinning box is responsible for evenly distributing the melt from the screw extruder to each spinneret. The system adopts precise pipeline design and distributor structure to ensure that the pressure drop and flow rate of the melt in each distribution branch are uniform. For example, by using an equal pressure drop distributor, the size and shape of the flow channel inside the distributor are optimized to keep the melt at a stable flow rate and pressure during the distribution process, ensuring that the fiber quality ejected from each spinneret is uniform.
Heating and insulation device: In order to maintain a constant temperature of the melt in the spinning box, the spinning box is equipped with an efficient heating and insulation device. The heating device usually adopts an electric heating rod or heat transfer oil heating method, and the heating power is reasonably configured according to the box size and production requirements. The insulation layer uses high-performance insulation materials, such as ceramic fiber wool, whose thermal conductivity is as low as 0.03 - 0.05W/(m・K), which effectively reduces heat loss and ensures that the temperature fluctuation inside the spinning box is controlled within ±1℃, providing a guarantee for a stable spinning process.
3.3 Spinneret
Micropore design and manufacturing process: The micropore design of the spinneret is the key to determining the cross-sectional shape and specifications of the fiber. The manufacturing process of the micropore adopts advanced laser drilling, electrospark machining or electroforming technology. Laser drilling technology can achieve high-precision micropore processing, with the aperture tolerance controlled at ±0.005mm and smooth hole walls, which can effectively reduce the resistance and wire breakage of the fiber during extrusion; electroforming technology can produce micropores of complex shapes to meet the production needs of special-shaped fibers, and the product consistency is good.

Spinneret material and surface treatment: The spinneret material is made of high-temperature resistant, corrosion-resistant, high-strength nickel-based alloy or stainless steel, such as Inconel 718, 316L, etc. In order to improve the anti-clogging performance and service life of the spinneret, its surface is specially treated, such as using physical vapor deposition (PVD) technology to coat a layer of titanium nitride (TiN) film, the thickness of which is generally 0.5-2μm. The film has the characteristics of high hardness, low friction coefficient, good chemical stability, etc., which can effectively reduce the adhesion and coking of the melt in the micropores and ensure the smoothness of the spinning process.
3.4 Drawing device
The hot air flow generation and delivery system of the drawing device consists of a heater, a fan, an air filter, etc. The heater heats the air to the set temperature, generally 150-300℃, and removes impurities and particulate matter in the air through a high-efficiency air filter to ensure the cleanliness of the hot air flow. The hot air flow is evenly delivered to the spinning tunnel through the delivery pipeline. The delivery pipeline adopts a special structural design to ensure that the speed distribution of the hot air flow in the tunnel is uniform, reducing the adverse effects of air turbulence on fiber drawing.
Optimization of drafting tunnel structure: The structure of the drafting tunnel plays an important role in the fiber drafting effect. By optimizing the length, width, height of the tunnel and the position and size of the airflow inlet and outlet, the hot airflow forms a stable and uniform drafting field in the tunnel. For example, a tapered tunnel structure is used to gradually accelerate the hot airflow in the tunnel, exerting a more uniform drafting force on the fiber; the inner wall of the tunnel is made of smooth materials and special surface treatment to reduce the friction between the airflow and the tunnel wall, further improving the drafting efficiency and fiber quality.
3.5 Web-forming machine
Mechanical web laying and air-laying equipment: Mechanical web laying equipment is mainly composed of a combing mechanism, a web laying curtain, a transmission device, etc. The combing mechanism combs the fiber into a single fiber state, and evenly lays the fiber on the web-forming curtain through the reciprocating motion of the web laying curtain. The movement speed and angle of the web laying curtain and the combing parameters of the combing mechanism can be precisely adjusted according to product requirements to achieve fiber web laying with different gram weights and uniformity requirements. The air-laying equipment uses the airflow generated by the fan to blow the fibers and guide them onto the web curtain. By adjusting the airflow speed, flow rate and parameters of the fiber conveying device, high-speed and efficient web laying is achieved.
Web uniformity control technology: In order to improve the uniformity of the web, the web forming machine is equipped with advanced uniformity control technology. For example, an online laser detection system is used to monitor the weight and thickness distribution of the web in real time. When the web is detected to be uneven, the automatic control system is used to timely adjust the relevant parameters of the web laying equipment, such as the speed of the web laying curtain, the flow rate of the airflow, etc., to correct the web in real time to ensure that the web uniformity deviation is controlled within ±3% to meet the production requirements of high-quality products.
3.6 Hot rolling mill
Roller structure and heating system: The roller of the hot rolling mill consists of an upper roller (engraved roller) and a lower roller (smooth roller). The roller is made of high-quality alloy steel, and after precision processing and heat treatment, the surface hardness reaches HRC55-60, with good wear resistance and rigidity. The rollers are equipped with an efficient heating system, which generally adopts electric heating or thermal oil heating. The electric heating method realizes fast and accurate temperature control by installing electric heating wires inside the rollers; the thermal oil heating method uses thermal oil circulation to transfer heat to the roller surface, with uniform temperature distribution and high temperature control accuracy, which can ensure that the uniformity of roller surface temperature is controlled within ±2℃.
Pressure regulation and control system: The pressure regulation system of the hot rolling mill adopts hydraulic or pneumatic The pressure between the rollers can be precisely controlled by adjusting the pressure of the hydraulic cylinder or the air cylinder. The pressure adjustment range is generally 0.1-1MPa, which can be flexibly adjusted according to product requirements. The control system is equipped with a high-precision pressure sensor to monitor the pressure between the rollers in real time and feed back the pressure data to the PLC. The PLC automatically adjusts the pressure adjustment device according to the preset pressure value to ensure the pressure stability during the hot rolling process, thereby ensuring the quality stability of the product.
3.7 Winding machine and slitting machine
Tension control and roll diameter detection of the winding machine: The tension control system of the winding machine adopts advanced sensors and controllers. By detecting the tension of the cloth surface and feeding back to the controller in real time, the controller automatically adjusts the speed of the winding motor and the braking force of the brake device according to the preset tension value to achieve precise control of the tension of the cloth surface, and the tension fluctuation is controlled within ±5N. The roll diameter detection system adopts photoelectric sensors or ultrasonic sensors to monitor the roll diameter changes of the cloth roll in real time. When the roll diameter reaches the set value, the roll changing device is automatically triggered to ensure the continuity and efficiency of the winding process.
The tool system and positioning accuracy of the slitting machine: The tool system of the slitting machine adopts high-quality alloy steel tools or diamond tools. The tools are sharp and durable, which can ensure that the cuts are neat and burr-free during the slitting process. The positioning system adopts high-precision servo motors and ball screws, combined with advanced visual inspection technology, to achieve precise control of the slitting position, and the slitting accuracy can reach ±0.5mm. At the same time, the slitting machine has functions such as automatic counting and automatic stacking, which improves production efficiency and the convenience of product packaging.
4. Advantages and characteristics of PET spunbond production line
4.1 Product performance advantages
High strength and good dimensional stability: PET spunbond nonwoven fabrics have high strength due to the highly oriented and crystalline structure formed by the fibers during the production process. Its tensile strength is generally 10-30N/5cm, which is much higher than ordinary nonwoven fabrics, and can meet the stringent requirements for material strength in industries such as industry and construction. At the same time, the characteristics of the PET material itself give the product good dimensional stability. Under different temperature and humidity environments, the size of the product changes very little, ensuring the stability and reliability of the product during use.
Weather resistance and chemical stability: PET spunbond nonwovens have excellent weather resistance and can be used outdoors for a long time without aging or fading. Under harsh environmental conditions such as ultraviolet radiation and rain erosion, its performance remains stable and has a long service life. The product has good tolerance to most chemical substances, is not prone to chemical reactions in acid, alkali, organic solvents and other environments, does not swell or dissolve, and can be widely used in filtration and protective materials in the fields of chemical industry and environmental protection.
4.2 Production efficiency and cost advantages
Continuous production and high production capacity: The PET spunbond production line adopts a continuous production process, from raw material input to finished product output, the production process is efficient and smooth. The speed of the production line is generally 10-150m/min. Depending on the product specifications and equipment configuration, the production capacity can reach several tons to tens of tons per day. For example, a PET spunbond production line with a width of 3.2m, calculated as working 24 hours a day, can produce spunbond nonwovens with a gram weight of 30g/㎡, with a daily output of 8-12 tons, which greatly meets the large-scale market demand and improves the production efficiency of enterprises.
2. High raw material utilization and cost control: In the PET spunbond production process, the utilization rate of raw polyester chips is significantly improved by optimizing the process flow and equipment configuration. From chip drying to final product molding, each link is closely coordinated to reduce the waste of raw materials caused by unreasonable process. At the same time, as a widely produced and relatively stable chemical raw material, the procurement cost of polyester chips is also effectively controlled with the maturity of production technology and the expansion of market scale. In addition, the high degree of automation of the production line reduces the investment of labor costs, making PET spunbond nonwovens highly competitive in production costs, which is conducive to enterprises to obtain greater profit space in the market.
5. Application fields of PET spunbond production line
5.1 Medical and health field
Medical protective products: In the medical and health industry, PET spunbond nonwoven fabrics have become an important material for medical protective products due to their good barrier properties, soft feel and excellent hygiene properties. For example, medical protective clothing, which uses PET spunbond nonwoven fabrics and other functional materials to effectively block the penetration of microorganisms such as bacteria and viruses, has good breathability, and allows medical staff to maintain comfort during long-term wear. The outer and inner layers of medical masks are also often made of PET spunbond nonwoven fabrics. The outer layer plays a protective role to prevent the entry of droplets, dust, etc., while the inner layer contacts the skin and has soft and skin-friendly characteristics, providing users with a good wearing experience.
Sanitary products: In terms of sanitary products, PET spunbond nonwoven fabrics are widely used in products such as baby diapers and adult incontinence pads. Its soft texture will not irritate the skin, and it has a certain strength and is not easy to break during use. Moreover, the good water absorption and water retention of PET spunbond nonwoven fabrics can quickly absorb liquids and keep the surface dry, providing users with a dry and comfortable environment. By using it in combination with materials such as highly absorbent resins, the performance of sanitary products is further improved, meeting the market demand for high-quality sanitary products.
5.2 Agricultural field
Agricultural covering materials: In agricultural production, PET spunbond nonwoven fabrics can be used as agricultural covering materials, such as greenhouse covering cloth, ground film, etc. It has good thermal insulation performance, can reduce heat loss in winter, and provide a suitable growth temperature for crops; at the same time, it has a certain light transmittance to ensure that crops can receive enough light. PET spunbond nonwoven fabrics also have windproof, dustproof, bird-proof and other functions, effectively protecting crops from the external environment and improving the yield and quality of crops. Moreover, compared with traditional plastic ground films, PET spunbond nonwoven fabrics are degradable, can reduce pollution to the soil environment, and meet the requirements of sustainable development of modern agriculture.
Gardening and seedling cultivation: In the field of gardening and seedling cultivation, PET spunbond nonwovens are used to make seedling pots, seedling trays, etc. Its breathable and water-permeable properties are conducive to the growth and development of plant roots, allowing the roots to breathe and absorb water and nutrients better. At the same time, PET spunbond nonwovens are soft in texture and will not damage plant roots. They are convenient and quick during transplantation, which improves the survival rate of transplantation. They can also be used to make plant support nets, sunshade nets, etc., to provide good environmental conditions for plant growth and promote the development of the horticultural industry.
5.3 Construction field
Waterproof materials: In building waterproofing projects, PET spunbond nonwovens are often used as the base material of waterproof rolls. After being compounded with waterproof materials such as asphalt, it can enhance the tensile strength, tear strength and puncture resistance of waterproof rolls, and effectively prevent water penetration. The good dimensional stability of PET spunbond nonwovens makes it difficult to deform under different temperature conditions, ensuring the construction quality and waterproof effect of waterproof rolls. Moreover, it has good bonding performance with waterproof materials, can be closely combined to form a continuous and complete waterproof layer, and is widely used in building waterproofing projects such as roof waterproofing and basement waterproofing.
Geotextile: Geotextile made of PET spunbond nonwoven fabric also plays an important role in construction projects. In road construction, geotextile can be used for roadbed reinforcement, road surface crack prevention, etc. It can evenly disperse the stress of the roadbed, improve the bearing capacity of the roadbed, and prevent cracks and collapse in the road surface. In water conservancy projects, geotextiles are used for dam anti-seepage and anti-filtration, effectively preventing the loss of soil particles, while ensuring the normal penetration of water, and playing a role in protecting the safety of the dam. In projects such as landfills, geotextiles can be used as isolation layers and anti-seepage layers to prevent leachate from polluting the soil and groundwater and protecting environmental safety.
5.4 Packaging field
Food packaging: In the food packaging industry, PET spunbond nonwoven fabrics are widely used in food packaging bags, packaging liners, etc. due to their non-toxic, odorless, hygienic and safe characteristics. It can effectively block the penetration of gases such as oxygen and water vapor, and maintain the freshness and quality of food. At the same time, PET spunbond nonwoven fabrics have good flexibility and printability, and can be personalized and printed according to the needs of different foods, improving the aesthetics and market competitiveness of products. For example, in food packaging such as bread and pastries, PET spunbond nonwoven fabric packaging lining can effectively prevent food from sticking and breaking, and maintain the appearance and taste of food.
Industrial packaging: In industrial packaging, PET spunbond nonwoven fabrics are used to make cargo packaging cloth, packaging bags, etc. Its high strength and wear resistance can effectively protect goods from damage during transportation and storage. Moreover, PET spunbond nonwoven fabrics are light in weight, which can reduce packaging and transportation costs. In addition, by giving it special treatments such as antistatic treatment and moisture-proof treatment, it can meet the packaging needs of different industrial products and is widely used in the packaging of electronic products, mechanical parts and other products.
5.5 Automotive Industry
Interior Materials: In the automotive interior field, PET spunbond nonwovens are widely used in automotive seat fabrics, ceiling linings, door interior panels and other parts due to their soft feel, good sound insulation and decorative properties. It can create a comfortable and quiet driving environment in the car, and at the same time, through different colors and texture designs, it can enhance the beauty and grade of the car interior. Moreover, PET spunbond nonwovens have good flame retardant properties, meet the safety standards of automotive interior materials, and ensure the safety of drivers and passengers.
Filter Materials: In automotive engine systems and air-conditioning systems, PET spunbond nonwovens are used to make filter materials such as air filters and oil filters. Its fine fiber structure and good filtering performance can effectively filter dust, impurities in the air and pollutants in the oil, ensure the normal operation of the engine and air-conditioning system, and extend the service life of the equipment. At the same time, the oil resistance and high temperature resistance of PET spunbond nonwovens enable it to work stably in harsh working environments, meeting the strict requirements of the automotive industry for filter materials.