Antistatic finishing of knowledge

Between the fiber material or a fiber material relative to the friction with other objects, it is often different or the positive and negative electrostatic charges of different sizes. Generally speaking, almost any two surfaces in contact with each other and with the separation of the friction generates static electricity.
Two surface charge characteristics depend on the electron flow and friction power-up sequence, the power-up sequence textile fibers used are as follows:
+ Nylon wool ramie cotton silk viscose acetate fibers PVA Polyester nylon and polypropylene -
When the two fabric rubbing against each other when the power-on sequence to the left of the fiber is positively charged, while on the right side of the fiber with an equal amount of negative electricity. Friction such as cotton and polyester, cotton is generally positively charged, negatively charged polyester. The friction cotton and silk, the cotton is negatively charged, positively charged silk. Affect fiber with power of many factors, but mainly depends on the fiber hygroscopicity and air relative humidity and friction conditions. The better the hydrophilic fibers, the more moisture, the lower the charge level. Because fiber micro fiber surface and is easy to form capillary surface water film or fibers in water vein, is conducive to the discharge electrons or ions escape. Natural fibers such as cotton, wool, silk, linen and other high moisture absorption, low resistance, electrostatic phenomenon is not serious, and synthetic fibers as low moisture absorption, high crystallinity and other features easy to produce static electricity.
The lower the relative humidity of air, the lower the moisture absorption of the fiber, even though the hydrophilic fibers, and also because low hardness and static regain. Because even the hydrophilic fibers in the absolute dry condition is an insulator.
The rougher the surface of the fiber, the greater the friction coefficient, the contact point, the more prone to static electricity. Two relative friction surface faster, then the greater the chance the contact point, the charge density, the higher the potential difference. Friction, the greater the pressure between the fibers, the friction area is larger, with a greater power. The temperature of the fiber material also affect the amount of static electricity, the temperature increased, the resistance decreased with reduced power consumption.
Textiles static electricity generated on the production of textiles and textile use will have a big impact, and even dangerous. For example, in the drying, the fabric moisture content decreased, not export static, often adsorbed on the metal parts, the disorder binding. The same fabric as the charge of the same, the occurrence of mutually exclusive, so that is not easy to drop cloth folded neatly under the influence of channel processing. Operator's hands and dry cloth in contact with the charge often subjected to electric shocks, easy absorption of clothing with electrostatic dust and pollution, taking clothing with electrostatic abnormal state occurs after deformation, such as skirts stick on the socks, underwear, outerwear close to the upper . Fabric with electrostatic discharge phenomena often, if the explosion area, prone to explosion. Generation of static electricity can also affect the normal process of high-speed spinning mills conducted static on raising machine often makes fabric pilling difficulties, from out of the fluff disorders and rewind decapitated. So for antistatic finishing of textiles is necessary.
An anti-static methods
Eliminating static methods are generally fabric physical and chemical methods of two kinds.
1, the physical static method
Such as the use of the power-up sequence of the fiber, and the opposite electric charge to eliminate or reduce the amount of static electricity, such as polyester blended; with increasing fiber lubricating oil can reduce the processing of the friction, such as synthetic fiber spinning oil added agent; electrostatic charge size, depending on the dielectric constant between the fibers, dielectric constant higher the value, the more easily escape static electricity. Therefore, if the wetting between the fibers to increase the dielectric constant of air, can be reduced with power. Such as raising machine for wet spray to eliminate static electricity. Can also be grounded to ground the static electricity on the fibers or increase the relative humidity of the working environment, as by weaving the wet plant to eliminate static electricity.
2, chemical static method
Finishing with the antistatic agent to eliminate static electricity.
⑴ increase fiber absorbency with a hydrophilic nonionic surfactant or a polymer substance order. Water has a very high conductivity, so long as the amount of water absorption, can significantly improve the conductivity of the polymer material. Therefore, antistatic finishing main function is to improve the absorption capacity of fiber material, to improve conductivity and reduce static phenomenon.
Antistatic effect of surfactants is due to it forming an adsorption layer on the fiber surface, the adsorption layer of surfactant hydrophobic tails attract each and hydrophobic fibers, the polar end is pointing to the outside, to enhance the fiber surface hydrophilicity , which can easily increase due to the relative humidity of air in the fiber layer formed on the surface of water absorption, lower than the resistance of the fiber surface. But such finishing agents due to the decrease of humidity in the air affect its antistatic properties.
⑵ ionic surface ionization by ionic surfactants or polymeric substance order. Such ionic finishing agent by the fiber surface moisture role ionized, electrically conductive, which can reduce the accumulation of static electricity. This finishing agent also has a water absorption, and therefore its antistatic ability and its capacity to absorb moisture and relative humidity of the air is also a relationship.
Two, antistatic finishing agent and its application
1, non-durable antistatic finishing agent
Non-durable antistatic finishing agent for fibers small affinity, intolerance wash, commonly used in synthetic fiber spinning oil and non-durable fabric wash infrequently antistatic finishing. This type of finishing agent from the surface of active agent.
⑴ anionic surfactants such as alkyl phosphates strong antistatic properties.
⑵ nonionic surfactants of this type finishing agent having a hydrophilic group such as-OH,-CONH2, and a polyether group. For example, fatty amines and fatty amides polyether derivatives are good antistatic agent.
⑶ cationic surfactants are generally quaternary ammonium salts, such antistatic agent reactive ion with a positive charge, the adsorption ability of the fiber, with excellent softness, smoothness, antistatic, as antistatic agents, and the softening agent, and has a certain degree of washability.
Non-durable antistatic finishing agent for processing general process is: padding antistatic finishing agent (one or two dip dip a second rolling mill, 5 ~ 20g / L) → drying (100 ~ 130 ℃).
2, durable antistatic finishing agent
Such finishing agent to the fabric has good durability, resistance to washing 20 times.
⑴ high molecular weight non-ionic antistatic finishing agent
◇ polyethylene terephthalate and polyoxyethylene terephthalate block copolymer: this type of finishing process finishing agents are often used in antistatic agents, and polyester having a similar chemical structure.
As these polyester finishing agent having a similar structure, when it enters the surface of the polyester fibers of Microsoft, the generation of the polyester molecules and fixed to the crystallization of the polyester to achieve durability. Finishing agent molecules in the polyoxyethylene group which has a hydrophilic polyester and has antistatic properties.
Finishing process: padding finishing agent → drying → heat treatment (180 ~ 190 ℃, 30s).
The purpose is to promote the high temperature treatment of crystallization, and with the heat-setting at the same time.
◇ acrylic copolymer: this type of finishing agent also has a similar ester and polyester, with a hydrophobic group belong, the carboxylic acid group orientation, imparts hydrophilicity and has conductivity.
Its finishing process is: padding finishing agent → drying → baking.
⑵ crosslinked film finishing agent for this kind of antistatic finishing agent applied to the film by cross-linking the fiber surface of the conductive layer of an insoluble polymer, such as polyoxyethylene group-containing polyhydric polyamine compound.
Wherein the hydroxyl and amino groups with a polyfunctional crosslinking agent to generate a linear or three-dimensional network structure insoluble polymer film to improve its washing properties. The crosslinking agent may be used in the reaction under acidic conditions or six 2D resin methylol melamine resin, it can be in reaction under alkaline conditions propionyl trimethoxy-triazine, its antistatic properties of the polyether hydrophilic generation.
Third, the size of the measure electrostatic
1, the surface resistance Rs than the surface specific resistance fiber static decay rate that the size of the surface of the material is numerically equal to the width and length of the resistance equal to 1cm, the unit is Ω.
2, the half-life t1 / 2 is the half-life of the fabric to measure the size of the electrostatic decay rate of the physical quantity, which means the fabric electrostatic charge decay to half the original value of the time required, the unit is s.
3, the mass ratio of the resistance of a homogeneous sample length 1cm, weight 1g represents the resistance value of a Ω, the unit is Ωg/cm2.
4, the friction between the static voltage or other textile articles after friction, electricity or electrical leakage triboelectric equilibrium voltage value.