Mar 10, 2020
Aerodynamics shows that particles smaller than 5 μm in diameter can cause greater damage to the body, and 1 to 2 μm particles can easily reach even deep parts of the respiratory organs, causing damage to the lungs. Harmful gases in the air are harmful to human health. The harmful effects of particulate matter and harmful gases on the human body, a series of masks came into being. However, due to the lag of relevant regulatory measures, the quality of masks varies, and many masks have more publicity effects than actual results.
The current research on masks includes three aspects: filtering method, filtering device structure, and filtering material. There are five kinds of filtration methods: simple type, electro-adsorption filter type, magnetic deviation removal type, chemical adsorption method, solution adsorption filtration method. There are three types of structural design of the respiratory filtering device: simple masks, masks equipped with auxiliary devices, and nasal filters. There are four types of filter materials: ordinary degreased gauze, non-woven filter materials, ultra-fine fiber high-efficiency filter cloth materials, and nano-materials. At present, the mask filtering methods on the market mostly adopt simple ear-hanging type, and the filtering device structure mostly uses simple masks. For filter materials, non-woven filter materials are mostly used. In recent years, people have also attached great importance to the research of filter materials. The porous structure of activated carbon makes it have a large specific surface area and thus has strong adsorption. Therefore, research into adding activated carbon components to masks is becoming increasingly common. There are three main ways: adding a layer of activated carbon to the mask Fibre cloth; Modification of activated carbon to make it adhere to the meltblown cloth; Introduce activated carbon particles into the melt gas jet to make the two compound. The above three methods have the disadvantages of high cost and complicated procedures. And the current research focus on masks mainly focuses on improving the filtration efficiency, and does not focus on the comfort of the inner materials of the masks. In order to solve the above series of problems, this paper has developed a cotton spunlace skin-friendly mask with low cost, good filtering performance, low breathing resistance, and more comfortable and safe.
Structural design and material selection of masks
Structural design of masks
The main factors to be considered in mask design are: filtering performance, tightness, and wearing comfort.
As far as the capture of particulates in fluids is concerned, fiber material filtration usually has a combination of six major filtration mechanisms: diffusion mechanism, direct blocking, inertia mechanism, gravity mechanism, electrostatic mechanism, and deposition caused by Coulomb-Vandervale force. Because polypropylene (PP) meltblown nonwoven filter cloth is composed of random ultrafine fibers with a single fiber diameter less than 4 μm, the fibers form a three-dimensional network structure with a large specific surface area and unique multidirectional curved channels. Can absorb, capture and block solid particles, is an excellent air filter material. Activated carbon is an amorphous porous powdery substance.Because of its large specific surface area and microporous structure, it has high adsorption capacity and high surface activity. Adsorption material. Therefore, the PP melt-blown nonwoven material and activated carbon were compounded, and the two formed a synergistic effect to achieve better filtration efficiency. Therefore, the filter layer of the mask uses a composite layer of meltblown filter cloth and activated carbon.
In order to improve a series of deficiencies in the composite process of meltblown material and activated carbon, the filter layer of the mask uses meltblown PP layer sandwiched with activated carbon powder. The key technology is how to make the activated carbon powder evenly distributed in the meltblown cloth. The process is simple and convenient. At the same time, the PP melt-blown layer between activated carbon and skin effectively prevents the escape of activated carbon and ensures safety.
As an important indicator for measuring the quality of a mask, if the gap between the outer edge of the mask and the face forms a gap, the airflow resistance here will be less than the filter material. According to the principle of fluid mechanics, the airflow will first flow to the place with low resistance and the mask will lose utility. The material of the inner layer of the mask is a low-area density non-woven fabric.The thinner the fiber layer, the better the applicability and the higher the degree of adhesion, and the use of a nose clip and the use of thin metal wires at the edges to further enhance the degree of adhesion. .
The inner layer of the mask uses pure cotton spunlace non-woven fabric, which is not easy to fluff and lint, has good air permeability, is soft and comfortable, and is provided with an appropriately sized cavity to improve comfort. The mask close to the face will cause air to flow through the filter material near the nose and nose, reducing the effective filtering area, large breathing resistance, and causing discomfort. The mask is provided with some flexible supports around the nose wing, so that the mask can form a cavity at the mouth and nose under the condition of ensuring tightness, which reduces the breathing resistance of the mask and improves comfort.
The outer layer of the mask is a polyester-viscous spunlace nonwoven with a weight of 22g / m2, of which 70% is polyester and 30% is viscose. Adding a certain amount of viscose fiber to polyester greatly improves the hydrophilic properties of polyester viscose spunlace nonwoven polyester viscose spunlace nonwoven combines the characteristics of polyester and viscose, has certain strength and water resistance, and is not easy to generate static electricity .
Mask middle layer
The middle layer is a composite layer of meltblown cloth and activated carbon. The meltblown layer is a meltblown non-woven fabric with a weight of 18 g / m2.
Considering the cost of raw materials, production costs, and polymer characteristics, such as relative molecular mass and its distribution, polymer melt viscosity and flow characteristics, and degradation properties, polypropylene is selected as the raw material in order to reduce energy consumption and improve Capacity. Because activated carbon has strong adsorption properties for gas impurities, the combination of activated carbon and meltblown nonwovens can achieve filtering effects on both gas and fine particles.
Innermost layer of mask
The inner layer of the mask is a pure cotton spunlace nonwoven with a weight of 18g / m2.
Chemical fiber can cause itching on the face and may cause allergies. Therefore, 100% cotton spunlace is used as the inner material. Cotton is a natural fiber and has good comfort properties.Its hygroscopicity, breathability, moisture permeability, moisture permeability, and antistatic properties are better than chemical fibers.It is soft, comfortable and safe, avoids itching, and the spunlace processing process will not bring Secondary pollution.