Negative ion fiber is a fiber with negative ion releasing function. Mainly during the fiber production process, a nanoscale tourmaline powder with negative ion releasing function is added, so that these tourmaline powders are embedded on the surface of the fiber. The electrons emitted by these tourmalines hit the oxygen molecules around the fiber, turning them into negatively charged oxygen ions.
At present, the negative ion fibers on the market mainly include viscose negative ion fiber, polyester negative ion fiber, polypropylene negative ion fiber, acrylic negative ion fiber, etc.
Test standards
Regarding the detection method of negative ion concentration, there is currently no unanimously recognized technical standard at home and abroad. However, in various countries and regions, experts and scholars engaged in the research of negative ion functional materials are working hard to discuss and have gradually reached a consensus.
Up to now, there are six main standards related to negative ions at home and abroad:
Test methods
Divided into static method and dynamic method.
The static method refers to placing the textile to be tested under the air ion analyzer in a sealed chamber, and reading the test data after stabilization.
The dynamic method refers to rubbing the sample under specified conditions in a test chamber of a certain volume, and using an air ion analyzer to measure the number of negative ions excited per unit volume when the sample and the sample itself rub against each other.
GB/T 30128-2014 “Detection and Evaluation of Negative Ion Generation in Textiles” and SN/T 2558.2-2011 “Inspection Methods for Imported and Exported Functional Textiles Part 2: Negative Ion Content” stipulate the dynamic method for the determination of negative ion generation in textiles.
GB/T 30128-2014 provides evaluation criteria for the negative ion generation amount of samples, as shown in the table below.
Testing instruments
The air ion meter is a special instrument for measuring gas ions in the atmosphere. It can measure the concentration of air ions, distinguish the charge of ions, and identify the size of ions based on the difference in mobility of ions. Air ion measuring instruments usually use a capacitive collector to collect the charges carried by air ions, and measure the current formed by these charges through a micro-amperometer. In addition to the collector, the measuring instrument also includes polarization power supply, microcurrent amplifier and DC power supply.
According to the different collector structures, air ion measuring instruments are also divided into two types: cylindrical type and flat type. The cylindrical collector is composed of two concentric circles. The outer cylinder is the polarizing pole and the inner cylinder is the collecting pole. However, the cylindrical collector has many problems and the test accuracy is not high. The flat plate ion collector consists of two parallel polarizing plates and a collecting plate. After the positive and negative ions enter the collector with the sampling airflow, they are deflected to the collection plate and polarization plate respectively according to different polarities under the action of the electric field between the collection plate and the polarization plate, and the charges they carry are transferred to the collection plate and polarization plate. on the chemical board. The charge collected on the collection plate falls through the microcurrent meter, forming an electric current. At the same time, the charges collected on the polarization plate fall to the ground through the polarization power supply and are recombined without affecting the measurement. Under normal circumstances, each air ion only carries one unit of charge, and the ion concentration can be obtained by converting the measured current and sampling air flow rate.
At present, air ion measuring instruments at home and abroad basically use flat capacitors as ion collectors. Among them, the air ion measuring instrument produced by AlphaLab Company in the United States is widely used, and its measurement accuracy can reach 10 ions/cm3. However, since the test is obviously affected by environmental and human factors, and the readings are not stable, the credibility of the test results has been questioned.
The IntiproITC-403A air ion measuring instrument of Japan’s Andes Company has a high degree of automation and is easy to use. The domestic air ion measuring instrument has reached the international advanced level in technology, and has obtained the invention patent for the static method air ion measuring instrument. It is not only innovative in theory, but also has a high degree of automation, and has overcome the disadvantages of flat-panel instrumentation to a certain extent. There are some inherent shortcomings of conventional ion measuring instruments.
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