- Created: 08-09-21
Description: Although auxiliaries have been a key component of immersion dyeing processes for many years the precise mode of action of many auxiliaries has not been fully resolved. This part of the paper discusses the various types of auxiliary available and the nature of the assistance they provide in immersion dyeing processes, together with both environmental and financial aspects associated with their use, as well as a discussion of the relationship between liquor ratio and the use of auxiliaries in immersion dyeing. The purpose of functional additives is to facilitate a textile process and/or increase its efficiency. They serve as sizing materials, lubricants, wetting agents, emulsifiers, agents accelerating or decelerating the dyeing rate, thickeners, binders, etc. often with considerable overlap in the functions and abilities of a specific chemical. Compounds used encompass many different chemical classes, some of which are affected by enzymes and thus can be regarded as substrates, and some of which remain unaffected. Owing to environment and economical concerns, pre-treatment auxiliaries are used as sparingly as possible. Once the respective process is terminated they are to be removed completely from the treated material; however, traces could still be present and interfere negatively with subsequent processing steps. Sizing compounds and lubricants are applied to yarns before fabric formation to protect the integrity of the yarns. While increasingly faster weaving processes demand more enduring sizes, acrylic-based compounds, natural sizes that can be decomposed are still on the market. Such compounds comprise starch and starch derivatives, as well as soluble. Cellulose derivatives, with waxes often admixed.Desizing with amylases is one of the oldest enzymatic processes used in the textile industry. A comprehensive description of the process can be found in Uhlig (1998). Starch has also been very useful as a thickener in printing pastes and as a component of adhesives. In printing processes, starches are applied to guarantee a defined design and to avoid spreading of the printing paste. In the paper industry, starches increase sheet strength and, as coatings, improve the writing and printing properties of high quality paper. Dyeing and printing auxiliaries may be defined as substances that, when applied to a substrate provide color by a process that alters, at least temporarily, any crystal structure of the colored substances. Such substances with considerable coloring capacity are widely employed in the textile, pharmaceutical, food, cosmetics, plastics, photographic and paper industries. The dyes can adhere to compatible surfaces by solution, by forming covalent bond or complexes with salts or metals, by physical adsorption or by mechanical retention. Dyes are classified according to their application and chemical structure, and are composed of a group of atoms known as chromophores, responsible for the dye color. These chromophore-containing centers are based on diverse functional groups, such as azo, anthraquinone, methine, nitro, arilmethane, carbonyl and others. In addition, electrons withdrawing or donating substituents so as to generate or intensify the color of the chromophores are denominated as auxochromes. The most common auxochromes are amine, carboxyl, sulfonate and hydroxyl. It is estimated that over 10,000 different dyes and pigments are used industrially and over 7 x 105 tons of synthetic dyes are annually produced worldwide. Textile materials can be dyed using batch, continuous or semi-continuous processes. The kind of process used depends on many characteristics including type of material as such fiber, yarn, fabric, fabric construction and garment, as also the generic type of fiber, size of dye lots and quality requirements in the dyed fabric. Among these processes, the batch process is the most common method used to dye textile materials. In the textile industry, up to 200,000 tons of these dyes are lost to effluents every year during the dyeing and finishing operations, due to the inefficiency of the dyeing process. Unfortunately, most of these dyes escape conventional wastewater treatment processes and persist in the environment as a result of their high stability to light, temperature, water, detergents, chemicals, soap and other parameters such as bleach and perspiration. In addition, anti-microbial agents resistant to biological degradation are frequently used in the manufacture of textiles, particularly for natural fibers such as cotton. The synthetic origin and complex aromatic structure of these agents make them more recalcitrant to biodegradation. However, environmental legislation obliges industries to eliminate color from their dye-containing effluents, before disposal into water bodies. The textile industry consumes a substantial amount of water in its manufacturing processes used mainly in the dyeing and finishing operations of the plants. The wastewater from textile plants is classified as the most polluting of all the industrial sectors, considering the volume generated as well as the effluent composition. In addition, the increased demand for textile products and the proportional increase in their production, and the use of synthetic dyes have together contributed to dye wastewater becoming one of the substantial sources of severe pollution problems in current times. Textile wastewaters are characterized by extreme fluctuations in many parameters such as chemical oxygen demand (COD), biochemical oxygen demand (BOD), pH, color and salinity. The composition of the wastewater will depend on the different organic-based compounds, chemicals and dyes used in the dry and wet-processing steps. Recalcitrant organic, colored, toxicant, surfactant and chlorinated compounds and salts are the main pollutants in textile effluents. In addition, the effects caused by other pollutants in textile wastewater, and the presence of very small amounts of dyes (
Publish Date: 08-09-21
Description: At present, DC brushless blowers mostly use brushless DC motors, which greatly simplify the structure of brushless DC motors by eliminating the collector ring and brushes for excitation. It not only improves the technical performance of the motor, but also greatly improves the mechanical reliability and life of the motor. Not only that, it also has excellent control performance compared with other motors. This is because the torque constant, torque inertia ratio, and power density of the motor have been greatly improved due to the high performance of permanent magnet materials. Through reasonable design, the inertia and electromechanical time constant can be greatly reduced and greatly improved as the main index of servo control performance. The design of modern permanent magnet circuit has been improved, and the coercivity of permanent magnet material is high. As a result, the armature response and demagnetization resistance of permanent magnet motors have been greatly improved, and the control parameters of the motors have been greatly reduced under the influence of external disturbances. Since permanent magnet is used instead of electric excitation, the design of excitation winding and magnetic field is reduced, thus reducing the parameters such as excitation flux, excitation winding inductance and excitation current, thus enabling the control variables or parameters to meet the design requirements. Direct reduction. All these factors can be said that DC brushless blowers have good controllability. DC brushless motors are widely used in daily life, so do you know the advantages of DC brushless motors, the following I introduce you to the characteristics of DC brushless motors. 1, no carbon brushes, low interference DC brushless motor in addition to carbon brushes, the most direct change is that there is no brush geared motor operation generated by electric sparks, which greatly reduces the interference of electric sparks to remote radio equipment. 2, low noise, smooth operation DC brushless motor without brushes, friction is greatly reduced when running, smooth operation, noise will be much lower, this advantage for brushless geared motor running stability is a huge support. 3, long life, low maintenance costs DC brushless motor less carbon brushes, brushless geared motor wear is mainly on the bearings, from a mechanical point of view, brushless geared motor is almost a maintenance-free motor, when necessary, only need to do some dusting maintenance can be. Brushless DC motor life is generally between several tens of thousands of hours, while the ordinary brush motor life is generally between 1000-2000 hours. 4、Energy saving and noise reduction DC brushless motor adopts frequency control and stepless speed regulation to realize indoor constant temperature control, which saves energy up to 50% or more than traditional AC fan coils. The blower is mainly composed of the following six parts: motor, air filter, blower body, air chamber, base (and oil tank), and drip nozzle. The blower runs eccentrically by the rotor offset in the cylinder and makes the volume change between the blades in the rotor slot to suck in, compress and spit out the air. In the operation of the blower using the pressure difference between the automatic lubrication to the drip nozzle, drip into the cylinder to reduce friction and noise, while maintaining the cylinder gas does not flow back, this blower is also known as the slide blower. The blower's types can be classified acccording to its applications, including, CPAP blower, Bipap blower, ICU ventilator blower, Purifying respirator blower, Air bed blower, Home appliance blower, etc. Application prospects of brushless DC motor Brushless DC motors have superior performance compared with other types of motors. Brushless DC motors are widely used in home ventilator motors, oxygen generators, small medical blowers and so on. Brushless DC motors have a good application prospect. However, there are still many problems to be solved and further research is needed. At present, the development of brushless DC motors has reached a relatively mature stage, but along with the continuous impact on materials, electronics and control technology, it is bound to develop in the direction of miniaturization, digitalization, long life and high reliability, and will certainly play a greater role in industrial production. Brushless DC motors are common in industrial applications across the world. At the most basic level, there are brushed and brushless motors and there are DC and AC motors. Brushless DC motors, as you may imagine, do not contain brushes and use a DC current. These motors provide many specific advantages over other types of electrical motors, but, going beyond the basics, what exactly is a brushless DC motor? How does it work and what’s it used for? How a Brushless DC Motor Works It often helps to explain how a brushed DC motor works first, as they were used for some time before brushless DC motors were available. A brushed DC motor has permanent magnets on the outside of its structure, with a spinning armature on the inside. The permanent magnets, which are stationary on the outside, are called the stator. The armature, which rotates and contains an electromagnet, is called the rotor. In a brushed DC motor, the rotor spins 180-degrees when an electric current is run to the armature. To go any further, the poles of the electromagnet must flip. The brushes, as the rotor spins, make contact with the stator, flipping the magnetic field and allowing the rotor to spin a full 360-degrees. A brushless DC motor is essentially flipped inside out, eliminating the need for brushes to flip the electromagnetic field. In brushless DC motors, the permanent magnets are on the rotor, and the electromagnets are on the stator. A computer then charges the electromagnets in the stator to rotate the rotor a full 360-degrees. What are Brushless DC Motors Used For? Brushless DC motors typically have an efficiency of 85-90%, while brushed motors are usually only 75-80% efficient. Brushes eventually wear out, sometimes causing dangerous sparking, limiting the lifespan of a brushed motor. Brushless DC motors are quiet, lighter and have much longer lifespans. Because computers control the electrical current, brushless DC motors can achieve much more precise motion control. Because of all these advantages, brushless DC motors are often used in modern devices where low noise and low heat are required, especially in devices that run continuously. This may include washing machines, air conditioners and other consumer electronics. They may even be the main power source for service robots, which will require very careful control of force for safety reasons. Brushless DC motors provide several distinct advantages over other types of electric motors, which is why they’ve made their way into so many household items and may be a major factor in the growth of service robots inside and outside of the industrial sector.
Publish Date: 08-09-21