The principle of laser marking for medical protective masks
Medical protective mask is a non-woven fabric material, which is composed of oriented or random fibers, and is generally a multi-layer structure, usually simply referred to as an SMS structure. At present, the highest number of layers is 5 layers, that is, SMMMS (spunbond, meltblown) are composed of polypropylene. The M layer uses meltblown nonwoven fabric as the filter layer. Because its fibers are randomly distributed and have a complex three-dimensional size, the biggest feature is that it is composed of ultrafine fibers, the specific surface area of the fiber, and the ability to adsorb particles is expected;
The fibers are randomly distributed to form a large number of tiny gaps, and the length distribution is uniform, the filter pore size is small, and the filtering efficiency is high, so that the filtering performance of the non-woven medical protective mask is far from the traditional gauze mask.SMS non-woven fabric uses polypropylene (with natural bacteriostasis and hydrophobicity) as the main raw material, and the fiber diameter can reach 0.5-10um. These ultrafine fibers with unique capillary structure increase the number and length of fibers per unit area, so that The fused laser marking surface is a non-woven fabric of S layer polypropylene material. Spray cloth has good air filterability and is a good material for many masks.
As with all medical and health products, anti-counterfeiting marks are an important part of mask products.Today, compared with traditional ink printing technology, laser marking has the characteristics of non-toxic, non-polluting, high efficiency, high resolution, high fineness, and wear resistance. problem. It can be said that laser marking technology has been escorting the medical industry since its birth.The principle of laser marking technology is mainly to irradiate the surface of the material with a laser with a high energy density, so that the surface of the material is vaporized to expose deep substances, or the chemical reaction of the surface of the material undergoes a color change under the effect of light irradiation. Because laser processing is a non-contact processing, the tool will not interfere with the direct friction of the workpiece surface, so the laser processing speed is extremely fast, and the processing object is affected by heat in a small range and does not generate noise. .
Due to the adjustment of the energy of the laser beam and the moving speed of the beam, the laser processing can be applied to different levels and ranges.Currently, there are two accepted laser processing principles: laser thermal processing and photochemical processing (also known as cold processing). Lingxiu Laser chose short-wavelength ultraviolet laser for marking process.
When the short-wavelength ultraviolet laser acts on the polymer, it directly breaks the chemical bond of the material, so that the material fragments are transferred in the form of small particles or gas, so as to achieve the purpose of replacing and removing the material, thereby generating a smooth, clear and readable mark inside the material . Since most of the energy is used to break chemical bonds, very little energy is converted into heat energy, which can basically eliminate the changes in the heat affected zone (HAZ) and surrounding materials, ensuring that the materials will not be deformed by heat.
Cold working (ultraviolet) photons with high load energy can break the chemical bonds inside the material (especially organic materials) or the surrounding medium, causing non-thermal process damage to the material. This kind of cold working is of special significance in laser marking, because it is not thermal ablation, but it does not produce “thermal damage” auxiliary, cold peeling that breaks the chemical bond, so it does not affect the inner layer and the surrounding area of the processed surface layer. Produce heating or thermal deformation.Because the transients generated by the hot processing light source cause damage to the outer and middle surface of the mask, which affects the filterability of the mask, the Lingxiu Laser replaces the “cold processing” ultraviolet laser to mark the surface layer of the mask.
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