Anti-static and ultra-clean fabric characteristics in anti-static clothing
Antistatic super clean fabrics used in antistatic overalls are often referred to as "conductive silk." In fact, this statement is not strict. Conductive silk can be divided into anti-static (ESD) and clean room (CleanRoom) according to its own technical characteristics. Only conductive silk suitable for clean room can be called Anti-static and ultra-clean fabric.
What is anti-static fabric? The anti-static processing fabric can be called anti-static fabric. Antistatic processing methods for fabrics usually include:
1 fabric is post-finished with antistatic finishing agent;
2 fiber graft modification, blending and interweaving of hydrophilic fibers for the purpose of improving fabric moisture absorption;
3 blended or inlaid conductive fibers;
The mechanism of action of the first two methods is to improve the moisture regain of the fabric, reduce the insulation, and accelerate the electrostatic leakage. Therefore, if the processing effect is not durable or inconspicuous in a dry environment or after repeated washing, it is usually applied to a fabric for general clothing. Only the third method can solve the static problem of textiles permanently and efficiently, so it is widely used in the production of anti-static overalls. The fabric is post-finished with an antistatic finish.
Anti-static fabrics can be woven fabrics, such as conductive silk, anti-static T/C fabrics, or knitted fabrics, such as anti-static knitted gloves, anti-electric knitted underwear. In addition to the general technical standards for textiles, anti-static fabrics must also have good anti-static properties to meet the production and safety requirements. Technical requirements can refer to GB12059-89 "synthetic fiber anti-static silk performance for the electronics industry
The difference between ultra-clean fabric and ordinary anti-static fabric in anti-static clothing
The difference between anti-static and ultra-clean fabrics and ordinary anti-static fabrics lies in the concept of “super clean”. Anti-static and ultra-clean fabrics must have the following three characteristics:
It has anti-static function: static electricity will absorb dust, and the absorbed dust will not be easily blown away when it is exposed to the air. Therefore, the primary feature of antistatic ultra-clean fabrics is antistatic properties. At the same time, this anti-static performance must be durable and efficient, and will not be significantly attenuated by daily washing and friction.
The fabric itself does not dust: because it is worn in a clean room, the fabric is not required to be a source of dust in the clean room, which determines that the ultra-clean fabric can only be produced from chemically synthesized long fibers. Natural short fibers such as cotton, hemp, and silk cannot be applied to ultra-clean fabrics, although these materials can make the fabrics more pleasing. At the same time, it is required that the selected chemical fiber filaments should also strictly control the amount of dust generated. In general, full-dull polyester filaments are not suitable for woven antistatic super-clean fabrics. Because the matting agent added to polyester production, titanium dioxide, will become a source of pollution.
The fabric should have good dust filter: the dust in the clean room mainly comes from the indoor air and the human body moving indoors. When the condition of the equipment is determined, improving the cleanliness means that the tiny dust generated by the human body is controlled to the inside of the clothes to let it pass through the fabric and enter the air. This is the so-called fabric with a high dust filter rate. Increasing the dust filter rate is at the expense of the breathability of the fabric, so knitted fabrics and woven fabrics that are relatively loosely woven are not suitable for use in clean rooms.
How to choose anti-static clothing super-clean fabric
Since our country has not yet developed corresponding testing standards for ultra-clean fabrics or clean clothes, the selection of anti-static and ultra-clean fabrics can only be selected by each application unit according to the requirements of the working environment or through testing or experience. Powerful users can spend hundreds of thousands to purchase a complete set of equipment, in the same environment as the actual application environment cleanliness, according to the ISO standard for each batch of clean clothing. Most users can only make choices based on experience (including the experience of others). To learn to choose the right clean fabric, you must first understand some basic knowledge about fabrics.
The woven fabric is formed by interlacing the yarns in the warp and weft directions at a specific arrangement density according to a specific structure. In a nutshell, what kind of raw materials are used, how much is tight, and what kind of pattern is woven. In order to weave anti-static ultra-clean fabrics, conductive fibers must also be added. Here, the yarn, (latitude and longitude) arrangement density, fabric structure and conductive fibers are the four elements of antistatic super clean fabric. The use of anti-static ultra-clean fabric is to compare the four elements of the fabric according to the cleanliness requirements of the working environment.
Identification of anti-static clothing super-clean fabric
Measuring the warp and weft density: The warp and weft density of the fabric is measured by the warp and weft density mirrors, and compared.
Resistance measurement: The warp and latitudinal resistance of the fabric were measured by a surface resistance tester and compared.
The principle of comparison is:
The selection resistance is relatively small;
If the resistance is the same, select the resistance value to be stable;
Pay attention to whether the fabric is added with antistatic agent during finishing (applicable to conductive silk with only conductive fibers in the warp direction, commonly known as striped cloth). The method is to measure the warp and weft resistance by surface resistance tester, if the same, Note that with the addition of antistatic agents, the measured resistance does not represent the true level.
Look at the microstructure: look at the quality of the cloth with a high magnification magnifying glass, compare the gap size between the fibers (related to the dust filter rate), see if there is any attachment on the fiber surface (related to the amount of dust), and see if the fiber arrangement is neat and tight. (If the tightness is inconsistent, the loose part of the fiber is easy to be worn when worn and washed, and will be dusted when worn later).
Check conductive fiber: Conductive fiber is the key material in anti-static ultra-clean fabric. Checking conductive fiber is to see if conductive fiber is added according to the specification and what kind of conductive fiber is added.
The method of inspection is: carefully cut the fabric along the edge of the black conductive fiber with scissors, and separate the black conductive fiber, use a magnifying glass to observe whether there is one or a few relatively thick fibers, and test with surface resistance. The instrument measures the electrical resistance of the separated conductive fibers. A few pieces are continuously removed, and it can be basically judged whether each black wire in the fabric contains conductive fibers. (The conductive silk is made of carbon organic conductive fiber, which is black or gray, generally around 20D, between 1F and 6F. In order to meet the strength requirements of weaving, an ordinary black or white polyester is required. fiber).
Comparing fabric process parameters: Suppliers are required to provide basic parameters of the fabric, such as yarn denier (how much D, how many F), warp and weft density, fabric texture, finished door width, dye shrinkage, and which conductive fiber to use.
The precautions for anti-static overalls when wearing and managing are as follows:
1, clothing should use all anti-static fabrics, generally do not use lining. When lining must be used, the exposed area of the lining should not exceed 20% of the total inside area of the garment.
2. According to the electrostatic sensitivity of different processing objects in different places, different grades of anti-static cloth and anti-static overalls should be selected.
3, the washing of the overalls should be carried out in a simple way, and should avoid the washing of the overalls by strong mechanical and chemical operations.
4. It is forbidden to attach or wear any metal objects on the anti-static overalls.
5. Do not put on or take off work clothes on the site where the static sensitive products are handled (should be changed in the designated locker room). The button of the overalls should be fully buckled, so as not to be close to the undressing state.
6. The anti-static overalls purchased in batches should be randomly selected several times to detect the charged power before being worn. After wearing for a certain period of time, especially when the wearer has a shock when undressing, a retest is required.