After the mask cover mouth, nose and chin some, constitute a medical mask and face seal space, by the suction force air through a mask when filtering harmful substances to protect effect. With continuous development of science and technology, the improvement of people's life and increasingly severe environmental pollution, human also continue to strengthen awareness of self-protection, masks, protective articles using non-woven mask is particularly common. At present the market circulation of the mask type is generally divided into air filter masks and gas mask, is widely used in air filtration mask, such as anti-dust masks, anti haze mouth Cover, mask, and for various types of masks introduced corresponding norms to regulate the mask mall. Protective respirator masks are mandatory norms China implementation of product standards, more of the test items. The fabric is breathable fabric characteristics, have greater contact with fabric and fabric combination way. Some masks first is composed of textile fiber materials, the permeability is also necessary. Some characteristics of mask mask ventilation performance to a certain extent determines the mask comfort, filtering and other anti power The support characteristics. At present, gas permeability detection mask does not have to check in contrast with the normative reference, and the primary air permeability of fabric inspection methods, such as GB / T5453 1997< textile fabrics Determination of air permeability > ASTMD737, 1996< > and the test method of air permeability of textiles ISO92371995< textile fabric air permeability determination.
First, the relationship between mask permeability and fabric structure
All the fabric structure is porous, the study showed that the pore and fabric breathable fabric, similar average pore size is bigger, its permeability is better. Different kinds of fabric aperture and permeability exist obvious differences, the same kind of fabric, because of its fiber material, yarn density, fabric structure, fabric density and fabric thickness are not the same, the fabric air permeability are very different. Because the permeability is far less than the single knit fabric double knitted fabric, the double needle Hazardous substances barrier fabric is very good. Because the non-woven generally show a single fiber network structure, has more breathable and harmful substances through the function, together with mesh non-woven fiber has more contact surface area, so it has stronger adsorption function.
The study showed that the fabric permeability with increasing number of performance significantly decreased. The rules of cotton fabric as an example, from single to double, permeability will decrease by about 50%; and continue to add fabric layers decreased to steep; when the fabric layer is added to the 6 layer, permeability only for single fabric 20%. and fabric layers and the relationship between the pore size and permeability of, is particularly important in the design of the respirator. When the mask of poor air permeability, exhaled gas can not be good to communicate with the outside world, resulting in waste gas masks in the tired When the mask has good ventilation, the exhaled air can communicate with the outside world very well, and people will feel breathing and dredge.
Second, the relationship between mask permeability and filtration power
The protective effect of the mask is based primarily on the filtering effect of the mask of harmful substances, filtering mask of harmful substances of high power, good air purification, air sucked into the body more healthy, protective masks effect is better, and the worse. At home and abroad have not the same power filter category masks clear rules, such as that at the request of GB190832010 medical protective mask technology, used in the medical environment in the mask, the filtering power mainly refers to non oil particles floating in the air filter, contain viral blood droplets, and other secretions. This Filter element class mask after interception effect, diffusion effect, gravity effect, inertial effect and electrostatic effect were barrier different size particles, however there is always a particle size of material can not fully filter, so the filter power first test of medical masks the most difficult to filter particles, get one of the most useful test results.
To have the comfort of the mask must have ventilation function, in theory, filtering power difference and mask ventilation function of mask has certain correlation. When the ventilation function masks especially when the mask itself is blocked outside the material into the mask, and then play a protective effect and power filter does not depend on the mask, but comfort is also the lowest, not suitable for the human body. When wearing masks permeability is better, and more frequent exchanges of material masks, which masks the filtration efficiency of the higher requirements to satisfy in the high frequency of material exchange The maximum limit, the masks can filter out the harmful substances in the air into the body, so as to play a protective effect. The mask ventilation function and filter power have good matching ability is very good to play a protective effect, and the establishment of mask ventilation function and filtering power between the model, find the relationship is it is necessary.
Third, the mask permeability and tightness of the relationship
Has a good basis to ensure the power filter mask with protective effect. The mask and face seal is bad, will occur cracks, cracks and air resistance is much smaller than the filter, based on fluid mechanics, because the air will flow from the priority place through small resistance, so no mask on the filtering effect is good, the mask the protective effect is not very high. Therefore, adhesion is an important condition to ensure anti-dust masks masks with protecting effect. Mask adhesion by total leakage rate in the laboratory showed that rule check condition, subjects inhale from the filter element, including a Cut into the mask mask component leakage imitation agent concentration and the percentage of inhalation agent concentration in the air of imitation, the total leakage rate is low, while the adhesion is higher. So the mask adhesion is better, on the request of the mask ventilation function is better, so to protect air through a mask to satisfy the need to breathe. On the other hand, adhesion of the mask of worse, there's no need for air and ventilation function request. Good masks, in a certain degree of request mask with sealing good, so to ensure that the mask has higher protective effect.
Forth,he influence of air permeability on mask quality
The most important quality is the mask of harmful substances has protective effect, the quality of the first performance in power to filter harmful substances, comfortable and close together and face wear degree. Between permeability and filtration power from the mask and adhesion can be inferred, the air permeability will be in a certain extent the protective properties of masks, which affect the quality of the comfort of wear masks. Performance for the first respiratory resistance to be small, light weight, not to stimulate the skin, wear clean, breathable function depends on the permeability of the fabric materials or masks. If he can mask when breathable comfort is high ,But on filtering power and adhesion also requires higher to guarantee its quality. And poor ventilation function, to ensure that the mask protective effect, its comfort will be reduced, which is of poor quality. Therefore, the permeability of the mask directly affects the mask comfort, indirect effects of filtering power and adhesion, and effect of mask quality.
The ventilation function is the first mask characteristics, depending on the fabric data structure and combination way. At the same time, permeability and influence of mask comfort, power filter and seal, thereby affecting the quality. So the establishment of a mask for detecting standard mask ventilation performance, is beneficial to improve the standard system Chinese masks, protection Chinese masks market order, and guarantee the use of Chinese masks' health.