There are many styles and designs of gas masks, most of which are made of hard plastic and soft rubber. Hard plastic is mainly used to support the mask and make it ventilated. Soft plastic is mainly used to consider the comfort of people wearing on the face and contacting with the human body. At present, environmental protection food grade material polypropylene (PP) is usually used as hard plastic. There seems to be a lot of room for the selection of soft rubber materials, such as soft PVC, silica gel, rubber, elastomer and PU. However, after comprehensive consideration, there are basically two kinds of soft rubber materials used in the production of anti-virus masks: silicone and TPU / TPU
why silicone and TPU are finally chosen as the raw materials for the soft part of the gas mask. This is mainly based on the following three aspects:
1. Environmental protection and non-toxic
silica gel is an environmental protection material that everyone agrees with. Food grade silica gel can be detected by fda177.2600, which is a kind of food contact material. 1n addition, silica gel has no smell, and it doesn’t smell uncomfortable. 1n addition, silica gel is a chemically stable material, human skin contact with silica gel without any discomfort or allergy
as for TPU. This is a kind of soft material that has been used increasingly in rubber and plastic industry in recent 10 years. TPU is environment-friendly and non-toxic. Through the SGS third-party testing, TPU | TPU conforms to RoHS, reach (SVHC), and does not contain toxic o-phenylplasticizer, bisphenol A, nonylphenol NP, polycyclic aromatic hydrocarbons (PAHs), and does not emit uncomfortable smell. TPU is mild in nature and has no allergic effect in contact with skin; TPU meets 1SO10993 biocompatibility test2. Soft touch
both silica gel and TPU can provide materials with suitable hardness, finding a balance between facial contact comfort and material strength. At present, the hardness of soft rubber TPU and silica gel used in gas masks is usually 45 ~ 50A. At the same time, both TPU and silica gel have good low temperature resistance (both can maintain soft elasticity at – 50 ℃)
3. One piece molding
TPU can be directly bonded with PP mask as a whole by injection molding, without the need of adhesive for assembly. This undoubtedly improves production efficiency. 1n recent years, modified silica gel can directly realize the injection bonding of the two materials without surface pretreatment of PP parts
generally, silica gel is suitable for making high-end gas masks, while TPU is used for middle and low-end products. Compared with TPU, the tensile deformation resistance of TPU is slightly inferior to that of silica gel. Of course, TPU material can be recycled 100%, which is not as good as silica gel