The oil of polyester filament can play a role in bundling, lubrication, reducing friction coefficient and antistatic. However, different types of oil have their own special functions and adaptability. The same type of filament will also be affected by the processing equipment. Different from the post-processing process, different oils are required. So, how should you choose an oil? 1. Requirements for the basic performance of oils
1. Smoothness
refers to the friction characteristics of oil. Commonly used are silk and silk (F/F), wire and metal (F/M) and wire after oiling. Expressed by the static friction coefficient (μs) and kinetic friction coefficient (μd) between rubber (F/R). After a better oil is applied to the yarn, the static friction coefficient of F/F should be appropriately large, the yarn has good bundling properties, good winding shaping, and excellent unwinding properties. There are no special requirements for the dynamic friction coefficient of F/F, but during false twist deformation, if the wire slides, it will easily deform. It is better for the static friction coefficient of F/M to be smaller, and the smaller the dynamic friction coefficient, the better. It can reduce the friction between the wire and the metal, reduce the hair and broken ends, reduce the wear of the wire on the metal, and improve the processing of the wire. and weaving performance. The static and dynamic friction coefficients of F/R are appropriate. Because during the processing, rubber parts are used to increase the holding force of the wire. If the friction coefficient is too small, it will easily slip.
Smoothness is determined by the properties of each component of the oil, and is also related to the lubrication condition. Lubrication when the oil content is high (0.5% to 1.0%) is fluid lubrication. In fluid lubrication, the friction coefficient increases with the increase in oil viscosity and oil content. The lubrication with the lowest oil content and the smallest friction coefficient is critical lubrication. Under critical lubrication conditions, in addition to the viscosity of the oil agent affecting the friction coefficient, the oil film strength (interfacial adsorption force, intermolecular cohesion) also has a great influence on the friction coefficient. The oil film strength is high and the friction coefficient fluctuates little.
2. Heat resistance
Needs to withstand thermal processing (drawing Stretching, false twisting, etc.) yarns have high requirements for heat resistance in terms of oil selection. Oils with poor heat resistance will decompose at high temperatures, and the physical properties of the oil will change. The volatilization of the oil at high temperatures will reduce the amount of oil and pollute the environment. The tar or oil droplets produced will also affect the operation.
3. Antistatic properties
Polyester is a good insulator. When it is rubbed during processing and use, negative static electricity will be generated due to the accumulation of charges. Static electricity makes the filaments loose and the processability deteriorates. Therefore, oiled fibers should be antistatic. There are usually three antistatic mechanisms: enhancing the hygroscopicity of the fiber, reducing friction, and neutralizing the generated charge. These three mechanisms can work at the same time.
4. Interface characteristics
The oil must have a certain degree of emulsification performance. The oil emulsification is stable, the emulsion has low surface tension and low viscosity, and can adhere evenly to the fiber surface. If the interface characteristics are not good, even if other performance is good, it will not meet the usage requirements.
2. Use of oil agent
1. According to the silk strip Purpose
Selecting oil agent woven silk requires good sizing properties. After sizing, the size film will not peel off or fall off very little during weaving. This requires good compatibility between the oil agent and the slurry. The oil agent whose smoothing agent is mineral oil has better sizing properties. Because the viscosity of mineral oil is low, its emulsion oil film is not only compatible with the slurry, but also easy to be redispersed. The oil agent and slurry are replaced on the surface of the fiber. The oil film protects the serous membrane.
The knitting yarn will be directly put on the machine for warping and weaving, which will cause high-speed friction with the knitting needles. It has high requirements for smoothness, bundling and antistatic properties. The used The oil viscosity should be low, the friction coefficient should be small, and the amount of oil should be high.
High temperature resistance should be the main feature of the oil used for false twist deformation, and its smoothness should be moderate. Too large or too small will cause tension changes, making the twist less smooth. uniform. In addition, the oil agent is required to produce less white powder and adhere evenly. Uneven adhesion affects the dyeing performance of the silk. When a certain oil is newly used, in order to avoid affecting production and product quality, it is best to trial it on a small scale before officially using it in production.
2. Oil dosage
The oil dosage is expressed in terms of silk strips Calculation of oil content (OPU). The OPU of conventional spinning and weaving yarns is 0.6% to 0.7%, knitting yarns are 0.7% to 0.9%, and texturing yarns are 0.5% to 0.6%. The amount of oiling in conventional spinning is affected by whether filaments and breakage occur during stretching. When the oil content is high, the tension of the yarn will increase, causing filament and breakage.
The OPU of high-speed spinning varies with the processing speed of the DTY machine. The higher the processing speed, the lower the OPU should be (see the table below). If high-speed spinning POY is used to draw drawn yarn, the amount of oil should be appropriately increased.
The finished oil agent re-applied to the deformed deformed yarn, POU for knitting is 2% to 3%, and for weaving It is 0.5% to 1.5%. It is used in the textured yarn of water-jet looms. In order to facilitate unwinding, about 0.5% oil is added. If the warp yarns are not sized, you can add about 1.5% oil after adding the network. For some special yarns, such as special-shaped yarns and colored yarns, the amount of oil should be 0.1% to 0.2% higher than that of ordinary yarns.
3. The concentration of oil agent
The concentration of oil agent is also affected by Restricted by many factors, considering the uniformity of oil adhesion on the silk, the lower the oil concentration, the better, but it will also cause the oil to splash easily. oneGenerally, the concentration of spinning oil is 10% to 15%, and the concentration of high-speed spinning oil is 8% to 15%.
4. Preparation of oil agent
In some varieties In filament oils, some components are not easily emulsified (dispersed) in water, and even if they are emulsified, they exist in the form of agglomerated complex particles. The size of the agglomerated complex particles is mainly determined by the initial emulsification conditions, that is, the conditions at the moment of contact between the oil agent and water.
(1) Water quality: Generally, ion exchange water can meet the requirements, but ion exchange water may contain silicon. If used for a long time, the combination of silicon and oil agent will easily block the oiling nozzle. .
(2) Temperature: When barreled oil is stored at low temperatures, component stratification will occur. In this case, you can place the oil drum in a 40°C water bath or warm room. After the solid part is dissolved, stir evenly before use. The water temperature during oil preparation varies with the performance of the oil agent, but is generally 20 to 30°C.
(3) Stirring: The oil agent needs to be stirred to be evenly injected into the water. The shorter the contact time between oil and water, the smaller the particles of the agglomerated complex formed. The oil is injected into the water with the fastest stirring speed in a thin stream, and the particles formed are small. When the stirring speed is 100~400r/min, the liquid flow rate near the kettle wall is the fastest. After the oil is injected, stirring should continue for about 30 minutes.
(4) Anti-corrosion of oil solution: During storage and use, the prepared oil will become corrupted and produce sediment, which will block the pipeline. Commonly used anti-corrosion methods: first, control the temperature, and second, add preservatives. Below 20°C, bacteria multiply slowly, above 25°C, bacteria multiply quickly. Below 18°C, the oil emulsion may precipitate, so the oil temperature should be controlled at around 20°C.
Preservatives are fungicides. The connecting joint at the rear of the oil nozzle of high-speed spinning is easy to clog, so there must be a bactericide in the oil. Conventional spinning is not necessary, but it must be cleaned frequently to keep the pipeline smooth. The dosage of fungicide is generally 110~500ppm. After using it for a period of time, bacteria will develop resistance, so its dosage should be increased. Using two fungicides alternately can improve resistance.
3. DTY and POY oils
(1) DTY oil agent
DTY oil agent is a finished oil agent. Its composition is 90% to 92% white oil, and the rest is emulsifier, antistatic agent and conditioner. Compared with conventional elastic yarn oils, DTY oil has the advantages of uniform oiling at high speed, high oil film strength, and good splash resistance, which can meet the needs of weaving and knitting.
(2) POY oil agent
The spinning speed of high-speed spinning is above 3000m/min, and the oiling amount is larger than that of conventional spinning Low, the oil agent is required to have good interface characteristics, be easy to disperse and penetrate, and can evenly adhere to the fiber surface. Oil is one of the key factors in winding molding. It can make the winding bobbin well formed and reduce the unwinding tension.
POY is mainly used for stretch deformation. The filament must be processed under conditions such as high temperature, high tension and high contact pressure, so the oil of POY must have heat resistance, It has the characteristics of higher oil film strength and less white powder production.
POY is generally not suitable as the original yarn for drawing multifilaments. It will cause a large dynamic friction coefficient between the fiber and the metal. When the friction coefficient is too large, hair will appear during drawing. Silk and broken ends affect product quality.
POY’s oil agent is mostly applied to the fiber through oil nozzle. In order to prevent the oil nozzle from clogging, the oil should be filtered and bactericide added. Because the delivery pressure of the oil pump fluctuates, this fluctuation has little effect when the oiling amount is high; when the oiling amount is 0.2% to 0.3%, it is difficult to evenly apply it. If the oil content is 0.3%, lint will appear easily. </p
