The pre-treatment of polyester yarn or fabric is generally based on oil removal, because spinning oil is added to polyester during spinning. So, what oils are generally used in polyester spinning oil? The following is about polyester spinning oil.
There are many types of polyester filament oils, including POY and DTY oils, conventional spinning Oil agent, stretch yarn oil agent, textured yarn oil agent and industrial silk oil agent, etc. They can all play a role in bundling, lubrication, reducing friction coefficient, antistatic, etc., but they have their own special functions and adaptability. Even for the same type of filament, due to different processing equipment and post-processing processes, the required oil agent The characteristics should also be different.
Polyester filament oils can be divided into two categories: spinning oils and finished oils. The basic properties of oils are the same, but the performance requirements of spinning oils are high. In finished oils.
1. Basic properties of oils
1. Smoothness Smoothness, or lubricity, is essentially the friction characteristic of oil.
The static friction coefficient (μs) between wire and wire (F/F), wire and metal (F/M) and wire and rubber (F/R) after oiling is usually ) and dynamic friction coefficient (μd). Generally speaking, after a better oil agent is applied to the wire, the static friction coefficient of F/F should be appropriately larger, so that the wire has good bundling, 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. The smaller the static friction coefficient of F/M is, the better. The smaller the kinetic friction coefficient, the better. This 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 wire quality. processing and weaving properties. 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 has a certain relationship with 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. At high speeds and high contact pressures, maintaining critical lubrication is of great significance. 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. Antistatic 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 loosens the filaments and deteriorates the processability. Therefore, oiled fibers should be antistatic. There are usually three antistatic mechanisms: enhancing the hygroscopicity of fibers; reducing friction; and neutralizing the generated charge. Three mechanisms can work simultaneously. The simplest method to measure the antistatic property of an oil is to measure the specific resistance of the wire after oiling. It can also measure the frictional charge of the wire.
3. Heat resistance For filaments that need to undergo thermal processing (drawing, false twisting, etc.), the heat resistance of the oil is very important. Oil will decompose at high temperatures and the physical properties of the oil will change.
The volatilization of oil agents at high temperatures reduces the amount of oiling and pollutes the environment. The tar or oil droplets produced will also affect the operation. The heat resistance of the oil agent can be measured by the volatilization loss method, that is, the oil agent is placed in an oven at 220°C for 8 hours, and its volatilization and decomposition loss are measured.
4. The interface characteristic oil must have certain emulsifying properties.
The oil emulsion is required to be stable, and the emulsion has low surface tension and low viscosity. Can be evenly adhered to the fiber surface. If the interface characteristics are not good, even if other performance is good, it will not be able to 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.
There are many brands of oils. When a certain oil is newly used, it is best to conduct a small trial before officially using it in production. Improper use will affect production and product quality.
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 also depends on whether lint and breakage occur during stretching, because when the oil content is high, the tension of the yarn will increase, causing lint and breakage.
High-speed spinning with DTY machineDepending on the speed, OPU changes. The higher the processing speed, the lower the OPU should be (see Table 1). If high-speed spinning POY is used to draw drawn yarn, the amount of oil should be appropriately increased.
The relationship between the processing speed of DTY machine and the amount of oiling
The finished product oil added to the deformed textured yarn is 2% to 3% for knitting, 0.5% to 1.5% for weaving, and 0.5% for the textured yarn of water-jet looms to facilitate unwinding. About oil. 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 depends on how much The constraints of these factors should be determined comprehensively and balancedly. From the perspective of the uniformity of oil adhesion on the yarn, the lower the oil concentration, the better. However, the oil is prone to splashing, especially in the oiling equipment of oil tankers, where the splashing is more serious. Generally, the concentration of conventional spinning oil is 10% to 15%, and the concentration of high-speed spinning oil is 8% to 15%.
4. Preparation of oils
In some varieties Some components in filament oil are not easily emulsified (dispersed) in water. 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) Temperature:
When barreled oil is stored at low temperatures, component stratification will occur. In this case, the oil drum should be placed 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 properties of the oil agent, but is mostly 20 to 30°C.
(2) Water quality:
Generally, ion-exchanged water can meet the requirements, but ion-exchanged water may contain silicon, which is difficult to use for a long time. , the combination of silicone and oil agent can easily clog the oiling nozzle.
(3) Stirring:
When the oil is injected into the water, it must be stirred evenly. 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) Preservation of oil solutions:
The prepared oils will become corrupted during storage and use. Precipitates are produced and pipes are clogged. Bacteria (microorganisms), oxygen, nutrient sources and temperature are the conditions for spoilage. There are two commonly used anti-corrosion methods. One is to control the temperature, and the other is to add preservatives. Below 20°C, bacteria multiply slowly, and above 25°C, bacteria multiply quickly. However, 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. It is best to use two fungicides alternately to improve resistance. </p
