How to optimize the fiber ratio and spunlace process parameters of PP/pulp composite spunlace fabric?

How does the fiber ratio of PP/pulp composite spunlace affect the mechanical properties of the product?

l To explore the effects of different PP fiber to pulp ratios on tensile strength, softness and liquid absorption

In PP/pulp composite spunlace fabrics, the ratio of PP fiber to pulp plays a key role in the mechanical properties of the product. In terms of tensile strength, PP fiber has high strength and modulus. Increasing the proportion of PP fiber within a certain range can help improve the tensile strength of the composite spunlace fabric. When the proportion of PP fiber is too low, the overall tensile strength will be limited due to the relatively weak strength of pulp fiber. However, too high a proportion of PP fiber may cause the flexibility of the fabric to decrease. Studies have shown that when the ratio of PP fiber to pulp is 6:4, the tensile strength can reach a relatively ideal value, which can meet the strength requirements of general application scenarios without sacrificing other properties too much.

In terms of softness, pulp fiber has a natural soft property. As the proportion of pulp fiber increases, the softness of the composite spunlace fabric is significantly improved. However, if there are too many pulp fibers, the structure of the fabric will become loose, thus affecting other properties such as tensile strength. For some applications that require extremely high softness, such as baby care products, the pulp fiber ratio can be appropriately increased to 7:3 or even higher, while compensating for the loss in strength by optimizing other process parameters.

Liquid absorption is closely related to the hydrophilicity of the fiber. Pulp fibers have good liquid absorption properties, while PP fibers are relatively hydrophobic. When the proportion of pulp fibers increases, the liquid absorption speed and liquid absorption amount of the composite spunlace fabric will increase. In the field of sanitary products, high liquid absorption is crucial. In order to achieve rapid absorption of liquid and keep dry, the ratio of PP fiber to pulp can be adjusted to 4:6 or lower to meet the product's demand for liquid absorption. However, it should be noted that excessive pursuit of liquid absorption and a large increase in pulp fibers may lead to a decrease in the strength and dimensional stability of the fabric.

l Analyze the key control points of fiber compatibility and mixing uniformity

Fiber compatibility is an important factor affecting the performance of PP/pulp composite spunlace fabrics. PP fiber is a thermoplastic synthetic fiber, while pulp fiber is a natural cellulose fiber. There are differences in the chemical structure and surface properties of the two, and the compatibility is poor. To improve the compatibility, the method of adding a compatibilizer can be used. For example, maleic anhydride grafted polypropylene (MAPP) is a commonly used compatibilizer, which can form a chemical bond between PP fiber and pulp fiber and enhance the interfacial bonding force between the two. In the production process, accurately controlling the amount of compatibilizer added is one of the key control points. Generally, the addition amount is 2%-5% of the total fiber amount. If the addition amount is too small, the compatibility cannot be effectively improved; if the addition amount is too large, the cost will increase and other properties may be negatively affected.

Mixing uniformity also has a significant impact on product performance. Uneven mixing can lead to differences in fabric performance, such as insufficient local strength or inconsistent liquid absorption. In the fiber mixing stage, it is crucial to use appropriate mixing equipment and processes. PP fibers and pulp fibers can be opened separately to fully disperse them, and then mixed by airflow mixing or mechanical stirring. During the airflow mixing process, control the airflow speed and flow rate to ensure that the fibers are evenly distributed and fully mixed in the airflow. When mechanically stirring, choose the appropriate stirring blade shape and speed to ensure that the fibers can be fully tumbled and mixed in the mixing container. At the same time, the mixing time must also be strictly controlled. Too short mixing time cannot achieve uniform mixing, and too long mixing time may cause fiber damage. Generally speaking, a mixing time of 10-15 minutes is more appropriate, and the specific time needs to be adjusted according to actual production conditions and equipment performance.

During the web-forming process, attention should also be paid to maintaining the uniformity of the mixture. Advanced web-forming equipment, such as carding machines and air-laid machines, should be used to ensure that the mixed fibers can be evenly distributed on the mesh curtain to form a fiber web. The carding effect of the carding machine has an important influence on the fiber arrangement and uniformity. The state of the carding clothing should be checked regularly, and the worn clothing should be replaced in time to ensure the carding effect. The air volume, air pressure and other parameters of the air-laid machine should also be precisely controlled to ensure that the fibers are evenly adsorbed on the mesh curtain under the action of the airflow to form a uniform fiber web.

What are the optimization criteria for spunlace process parameters during the production of PP/pulp composite spunlace fabrics?

l Effects of hydroentanglement pressure, arrangement of hydroentanglement needles and number of hydroentanglement channels on fiber entanglement

The spunlace pressure is one of the key parameters that affect the fiber entanglement effect of PP/pulp composite spunlace fabric. During the spunlace process, high-pressure water flow impacts the fiber web, causing the fibers to entangle with each other, thereby giving the fabric a certain strength. When the spunlace pressure is low, the water flow energy is not enough to fully entangle the fibers, the strength of the fabric is low, and the feel is relatively loose. As the spunlace pressure increases, the degree of fiber entanglement gradually increases, and the strength of the fabric is also enhanced accordingly. However, excessive spunlace pressure may cause fiber damage, especially pulp fibers, which have a relatively fragile structure and are prone to breakage under excessive pressure, which reduces the overall performance of the fabric. Generally speaking, for PP/pulp composite spunlace fabrics, the pre-spunlace pressure can be controlled at 30-50 bar, and the main spunlace pressure can be controlled at 70-100 bar. The specific values need to be adjusted according to factors such as fiber ratio and cloth weight.

The arrangement of the water needles also has a significant impact on the fiber entanglement effect. Common water needle arrangements include parallel arrangement and cross arrangement. Parallel arranged water needles impact the fiber web in the same direction, and the fiber entanglement direction is relatively single, which is suitable for products with high requirements for fabric flatness. Cross-arranged water needles impact the fiber web from different directions, which can entangle the fibers in multiple directions, improve the isotropic performance of the fabric, and enhance the overall strength of the fabric. In actual production, the appropriate water needle arrangement can be selected according to the final use of the product. For example, for medical spunlace fabrics, due to the high requirements for strength and isotropy, cross-arranged water needles can be used; for some decorative fabrics, more attention is paid to the flatness of the fabric surface, and parallel arranged water needles can be selected.

The number of spunlace passes also affects the fiber entanglement effect and product performance. Increasing the number of spunlace passes can further entangle the fibers and improve the strength and compactness of the cloth. However, too many spunlace passes will increase production costs and energy consumption, and may also cause excessive damage to the fibers. Generally speaking, for ordinary PP/pulp composite spunlace fabrics, 2-3 spunlace processes are more common. For some products with extremely high strength requirements, such as industrial filter cloths, the number of spunlace passes can be appropriately increased to 4, but close attention should be paid to fiber damage and energy consumption costs. When determining the number of spunlace passes, factors such as product performance requirements, costs, and production efficiency need to be considered comprehensively.

l How to balance spunlace energy consumption and product performance (such as fabric smoothness and strength)

There is a mutually restrictive relationship between hydroentanglement energy consumption and product performance. Although increasing hydroentanglement pressure and the number of hydroentanglement passes can improve product performance, it will lead to a significant increase in energy consumption. In actual production, it is necessary to find a balance between the two.

From the perspective of equipment selection and maintenance, it is crucial to choose efficient and energy-saving spunlace equipment. The new spunlace machine adopts advanced hydraulic system and energy-saving water pump, which can reduce energy consumption while ensuring stable spunlace pressure. At the same time, regular maintenance of the equipment is carried out to ensure that all parts of the equipment are in good operation and reduce energy waste caused by equipment failure. For example, clean the impurities on the water needle plate in time to ensure smooth water flow from the water needle, avoid increasing the water pump load due to water needle blockage, and thus reduce energy consumption.

In terms of process parameter optimization, energy consumption and product performance are balanced by precisely controlling the spunlace pressure, number of spunlace passes and arrangement of water needles. As mentioned above, the spunlace pressure and number of spunlace passes are reasonably selected according to the specific requirements of the product to avoid excessive spunlace. While ensuring that the flatness and strength of the fabric surface meet the requirements, the spunlace pressure and the number of spunlace passes are reduced as much as possible. For some products that have high requirements for fabric flatness but relatively low requirements for strength, the spunlace pressure can be appropriately reduced, and parallel arrangement of water needles can be used to reduce energy consumption while ensuring flatness. For products with high strength requirements, the spunlace pressure and the number of spunlace passes can be increased within a reasonable range, and the cost increase that may be caused by increased energy consumption can be compensated by optimizing the fiber ratio and other methods.

In addition, an intelligent control system can be used to monitor and adjust the spunlace process parameters in real time. Through the sensors installed on the equipment, the spunlace pressure, flow rate, fabric tension and other data are collected in real time and transmitted to the control system. The control system automatically adjusts the spunlace process parameters according to the preset product performance indicators and energy consumption targets to achieve a dynamic balance between energy consumption and product performance. For example, when it is detected that the fabric strength is close to the lower limit of the target value and the energy consumption is high, the system automatically fine-tunes the spunlace pressure and the number of spunlace passes to reduce energy consumption while ensuring strength.

How to control the uniformity of grammage of PP/pulp composite spunlace fabric?

l Optimization strategy for web uniformity and web laying process

The uniformity of web formation is the basis for controlling the uniformity of the grammage of PP/pulp composite spunlace fabric. During the web formation process, the uniformity of fiber distribution directly affects the uniformity of the fabric weight. First, ensure that the fibers are mixed evenly. As mentioned above, appropriate mixing equipment and processes are used to fully mix the PP fibers and pulp fibers. In the carding web formation stage, the carding effect of the carding machine is crucial. Select the appropriate carding machine clothing specifications, and adjust the speed and spacing of the carding machine's cylinder, doffer and other components according to the fiber characteristics, so that the fibers can be evenly transferred from the carding machine to the mesh curtain to form a fiber web. For example, for finer fibers, the spacing of the carding machine can be appropriately reduced to improve the carding effect and ensure a more uniform fiber distribution.

The air-laid machine also plays an important role in the uniformity of the web. The air volume, air pressure and air distribution of the air-laid machine are precisely controlled to ensure that the fibers are evenly adsorbed on the net curtain under the action of the air flow. By optimizing the air duct design of the air-laid machine, the air flow is evenly distributed across the width of the net curtain to avoid local fiber accumulation or sparseness. At the same time, the matching relationship between the fiber feed amount and the air flow speed is adjusted to ensure that the fibers can stably form a uniform fiber web on the net curtain.

The fiber web laying process also has a significant impact on the uniformity of grammage. Common fiber web laying methods include parallel laying and cross laying. Parallel laying can make the fiber webs evenly stacked in the thickness direction, but there may be uneven grammage in the transverse direction of the fabric. Cross laying can improve the uniformity of grammage in the transverse direction of the fabric and make the fibers more evenly distributed in multiple directions. In actual production, the appropriate laying method can be selected according to the product requirements. For some products that require extremely high uniformity of grammage in the transverse direction of the fabric, such as fabrics for high-end sanitary products, the cross laying process can be used. At the same time, the number of stacking layers and the grammage of each layer of fiber web are controlled to ensure that the grammage uniformity of the final composite spunlace fabric meets the requirements. By accurately controlling the running speed of the laying equipment and the fiber web delivery volume, the grammage of each layer of fiber web is guaranteed to be stable, thereby achieving the control of the overall grammage uniformity.

l Application of online monitoring and feedback adjustment technology in grammage control

Online monitoring and feedback adjustment technology is an effective means to achieve accurate control of the grammage of PP/pulp composite spunlace fabrics. Install high-precision online weight monitoring equipment on the production line, such as radioisotope thickness gauges or capacitive thickness gauges, to monitor the weight changes of composite spunlace fabrics in real time. These monitoring devices can quickly and accurately measure the weight of the fabric and transmit the data to the control system.

The control system analyzes and processes the monitoring data according to the preset standard weight value. When it is detected that the weight deviation exceeds the allowable range, the system automatically starts the feedback adjustment mechanism. For example, if the weight is too high, the control system can reduce the amount of fiber web formed by reducing the fiber feed amount and adjusting the relevant parameters of the carding machine or air-laid machine; if the weight is too low, the fiber feed amount is increased or the equipment parameters are adjusted accordingly to increase the amount of fiber web formed. In the hydroentanglement process, the hydroentanglement pressure and the number of hydroentanglement passes can also be appropriately adjusted according to the weight monitoring data to ensure that the weight is within a reasonable range while maintaining other product properties.

In order to improve the accuracy and timeliness of feedback regulation, advanced control algorithms such as PID control algorithms can be used. The PID controller accurately calculates the adjustment amount based on the three parameters of weight deviation: proportion, integration and differentiation, to achieve dynamic adjustment of the production process. At the same time, the online monitoring system is closely integrated with the automatic control system of the production equipment to form a closed-loop control system to achieve automatic control and optimization of the weight. By continuously optimizing the performance of the online monitoring and feedback regulation system, the control accuracy of the weight uniformity of PP/pulp composite spunlace cloth can be effectively improved to meet the increasingly stringent product quality requirements.