01 Introduction
High-temperature and high-pressure dyeing is an important dyeing method for polyester fiber. Due to the dyeing characteristics of polyester fiber and its special method of high-temperature and high-pressure dyeing, level dyeing for high-temperature dyeing is also unique. The leveling agent has special requirements, and due to the differences in the form categories of textile semi-finished products, there are further special requirements for high-temperature leveling agents. Therefore, in addition to the most basic properties such as slow dyeing and transfer dyeing that are suitable for high temperature conditions of 130°C, there should also be specialized varieties that are suitable for the dyeing characteristics of various types of polyester fiber semi-finished products. Otherwise, it will be difficult to apply in specific applications. It can well target the individual characteristics of various types in high-temperature and high-pressure dyeing, greatly reducing its applicability.
02 Different dyeing characteristics of different fiber semi-finished products
The types of textile semi-finished products of polyester fiber also include loose fibers, yarns, fabrics, etc. Many forms.
Loose fiber dyeing is required for color spinning. Yarn dyeing is mainly used for yarn-dyed weaving, followed by sewing and embroidery. Fabric dyeing is required for ready-made garments, home textiles, industrial fabrics, etc. The dyeing of fabrics is also divided into various forms such as loose dip dyeing, open jig dyeing and beam dyeing. Although they all use high-temperature and high-pressure dyeing methods, different forms of fiber semi-finished products must be matched with different dyeing equipment that conforms to their respective form characteristics; otherwise, the style, characteristics, and product quality of the textiles will obviously be severely affected. damaged, or even in terms of the viability of no staining.
The loose dip dyeing machine is suitable for weft knitting, warp knitting knitted fabrics, and wool-like style woven fabrics. Open-width jig dyeing is suitable for woven fabrics with no elasticity requirements, especially for thin filament-like silk woven fabrics, which are generally not suitable for this type of machine. For mesh type loose warp knitted fabrics (such as mosquito nets, etc.), a warp beam dyeing machine is suitable.
Yarns are mainly dyed in packages or caged skeins. Although loose fibers are also dyed in cages, they are quite different from caged dyeing of yarns.
03 High temperature leveling agent function and Personalized requirements
1. Basic functions of high-temperature leveling agent Hydrophobic disperse dyes are suitable for dyeing hydrophobic polyester fibers, but the hydrophobic nature of the dye determines its low water solubility. This should be said to be a rather contradictory thing in the dyeing process using water as the medium.
For this reason, commercial disperse dyes are mixed with a large amount of surfactants such as diffusing agents that are no less than the proportion of dyes. Generally dye:filler=1:1~1.5. As an additional high-temperature leveling agent added to the dyeing working bath, it also has a certain auxiliary and supplementary role in order to promote the suspension and diffusion state of disperse dye particles in the dyeing working bath and maintain a uniform and stable distribution. This is particularly important for light and medium colors with less dye consumption, because the amount of light and medium color dyes is correspondingly less, and the diffusing agent brought in from the dye is simultaneously reduced. High-temperature leveling agents are necessary. Provide some compensation.
Dyeing leveling requires ideal retarding function, which is the key function that all leveling agents must have. However, level dyeing of polyester fibers with disperse dyes must be combined with a strong dye migration function, because there is no chemical reaction from the beginning to the end of the dyeing of polyester fibers with disperse dyes; and the tight structure of polyester fibers and their extremely dense Characteristics such as the surface crystal layer play a key blocking role, and dye migration can make up for the gap in slow dyeing. Especially after reaching the 130°C insulation dyeing stage, most of the dye in the dye bath has been When the dye is applied to the fiber, the retarder function has basically completed its mission. The dye transfer function has become the main role at this stage. It will further promote and ensure the overall target effect of the leveling agent.
So, slow dyeing, dye transfer and diffusion aid are combined to form the most fundamental elements of high-temperature leveling agents, and they are also the basic functions that must be possessed in the use of various different dyeing machines.
2. Analysis and classification of personalized requirements The different dyeing operation modes of different dyeing machines have also produced personalized and special requirements for high-temperature leveling agents. In addition to the above basic necessary functions, it is also necessary to form a series of personalized and differentiated varieties such as low-foaming type, anti-sedimentation type, penetration-enhanced type, etc.
Low foam type and its applicability
For liquid flow, In jet and other nozzle type loose fabric exhaust dyeing machines, the dye bath is violently agitated due to the rapid operation of the fabric in the liquid flow, jet and other nozzle dyeing machines. Especially in semi-filled dyeing machines, certain auxiliaries and dyes are prone to foaming under these environmental conditions.
Leveling agents containing adducts of ethylene oxide are more likely to foam. If the foam continues to increase and reaches a certain level, the nozzle will form foamy air suction, causing the spray pressure to drop, eventually causing the gray fabric to stop passing. Once it stalls, it is very likely to produce color flowers, and wrinkle marks often occur. The longer the stall time, the more serious the consequences will be.
For this reason, the high-temperature leveling agent used in this type of dyeing machine should be low-foaming. Of course, from a subjective perspective, it is best to be bubble-free, but this is not in line with objective reality. The vigorous stirring effect of this type of dyeing machine from beginning to end during operation is essential for fully maintaining good suspension of undissolved dye in the dyeing bath.This state is very beneficial, but on the other hand, it is the source of power that constantly triggers bubbles. It is unrealistic and impossible to require complete bubble-free operation. Therefore, in semi-filled liquid flow and jet dyeing machines, it is still very necessary to use defoaming agents.
But it should be mentioned that in a fully filled jet dyeing machine, there is almost no need for foam. Another type of overflow dyeing machine, because the dyeing operation of gray fabrics is driven by the unpressurized gravity flow of water and does not have a nozzle, so there is no need to add an additional defoaming agent.
Anti-sedimentation type and its applicability
For high-temperature and high-pressure jigger dyeing machines, the operation of gray cloth is mechanical transmission, foaming It does not have much impact on the dyeing operation and dyeing effect. However, the operating characteristics of this type of dyeing machine are that it transfers cloth but not water, and the small bath ratio makes the dye g/l unit concentration of the same color formula in the dye bath much greater than that of liquid flow, jet type, bobbin, and loose fiber. Class dyeing machine (generally at least doubled). These correspondingly increase the objective conditions for the aggregation and precipitation of suspended dyes in the dye bath, so the probability of occurrence of color spot defects is much greater than that of dyeing machines equipped with powerful circulation pumps. Therefore, they especially need to adopt enhanced diffusion and anti-sedimentation functional types to be more suitable.
Penetration-enhanced type and its applicability
Bones, caged hanks, loose fiber dyeing machines and other equipment, also They are also equipped with powerful circulation pumps, but they are different from liquid jet dyeing machines in that the fiber is fully immersed in the dyeing working bath, and they do not use nozzles, so they do not have foam problems and anti-sedimentation requirements. Not very sharp.
However, their dyeing method characteristics are opposite to those of jigger dyeing machines, in which the water moves and the fibers do not move, and are much thicker than those of liquid flow machines, jet machines, jigger dyeing machines, etc., which use single-layer gray cloth as the dyeing operation method. For many fiber stack layers, including beam dyeing machines, in addition to the mechanical equipment required to have sufficient water penetration capabilities, the high-temperature leveling agent can supplement and strengthen the good effect of all fiber layers on the inner, middle and outer layers. Penetration performance is both important and necessary for the leveling of this type of dyeing machine. Therefore, for them, it is appropriate to use a penetration-enhanced high-temperature leveling agent.
04 Conclusion
Level dyeing is one of the main quality objectives of dyeing, so in dyeing , the role of leveling agent is very important. The high-temperature and high-pressure dyeing of polyester fiber has diversified the varieties of textile semi-finished products and the selectivity of dyeing equipment, which also brings about the diversity of functional requirements for high-temperature leveling agents. Therefore, the design and development of high-temperature leveling agents are inevitable and necessary in terms of variety series and specificity, so that they can well meet the actual needs of various types of production in high-temperature and high-pressure dyeing.
However, it must also be noted that leveling agent is not the only factor that determines leveling. Factors that affect leveling include the selection of specific dye varieties (compatibility), heating rate, vehicle blocking operation, and the status of the equipment. Only by reliably controlling all influencing factors can the leveling of dyeing be highly and stably reflected.
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