| Workers in workplaces such as mines,fiberglass factories,cement factories,asbestos factories,welding operation,and crushing workshops are exposed to inorganic fine dust such as mine dust,glass fibers,asbestos fibers,welding fumes,and dust particles.Even when wearing labor protection equipment such as masks,there are still 10,000-30,000 cases of pneumoconiosis per year,with a death rate exceeding 20%,which has caused numerous families to fall apart.To prevent inorganic fine dust from being inhaled into the workers’ lungs,wearing a mask needs to have both good filtration and sealing performance.Currently,most research on masks focuses on filtration performance,such as filter material types,filter material performance,and number of filter layers,and most masks have good filtration performance,such as N95 masks,which can achieve a filtration efficiency of over 95%.However,research on mask sealing is relatively less,and the main measure currently is to use a pliable nose strip for auxiliary sealing.Nevertheless,there may still be certain gaps between the mask and the face,leading to poor improvement in mask sealing.In order to improve the seal between the mask and the face,elastic ear loops are usually used to tightly secure the mask on the face,but long-term wearing of the mask will leave severe marks on the face,reducing comfort.Therefore,further research on mask sealing is needed.This study prepared a silicone/copolymer soft gel composite material that could improve the sealing performance of masks.Through formula optimization and process improvement,the structure and properties of the silicone/copolymer soft gel composite material and its interface structure with the mask and skin were studied,and a sealing material with good applicability was obtained.At the same time,a sealing detection device was built,and a detection method was designed to study the sealing performance of masks.(1)Due to its good flexibility,biocompatibility,and stability,silicone gel could be chosen as a mask sealing material.After formula optimization,its properties were studied.Modified fumed silica with hexamethyldisilazane was used to modify the silicone gel,and after further formula optimization,it was applied to mask sealing.Research showd that after formula optimization,the elongation at break of silicone gel doubles,and the peel strength from human skin increased by 1.5 times.The tensile strength of modified silicone gel improved by five times.After formula optimization of modified silicone gel,its tensile strength reached 136.7 KPa,the peel strength from human skin reached 0.042 N/10 mm,and the elongation at break reached 431%.Compared to before treatment,all aspects of performance had improved.The peel strength between silicone gel and human skin was5.6%～6.2% of medical tape and double-sided foam tape.Through actual testing,the adhesive performance between silicone gel and human skin was very suitable,as it could fit well with the skin without causing discomfort.However,the peel strength between silicone gel and the inside of the mask was only 0.021 N/10 mm,indicating poor adhesive performance,which could not achieve mask sealing,thus further research is needed.(2)To solve the problem of poor adhesion between silicone gel and the inside of the mask,copolymerized acrylic ester was introduced as an interface adhesive layer between silicone gel and the mask.This study used free radical solution polymerization to prepare copolymerized acrylic ester and studied its properties by changing the monomer type.Copolymerized acrylic ester was used as the interface adhesive layer between silicone gel and the inside of the mask,and was compounded with silicone gel to obtain a composite soft gel material(referred to as composite soft gel material),which was optimized for its structure and properties and used as a mask sealing material.By adjusting the ratio of butyl acrylate,iso-octyl acrylate,methyl methacrylate,and hydroxyethyl acrylate(the soft/hard monomer ratio)in the copolymerization of acrylic ester,the molecular chain of the copolymer and their individual effects were relatively unaffected(with a weight average molecular weight range of160,000-200,000 g/mol).However,introducing acrylic acid could cause a decrease in the molecular weight of the copolymer(5,000-8,000 g/mol).As the proportion of soft monomers in the copolymer of acrylic ester increases,the glass transition temperature of the copolymer decreased from 13.36 to-60.44℃,and the bonding performance of the copolymer of acrylic ester with low glass transition temperature was better.For the sample BA/EHA/HEA(mass ratio of 52/24/24),its glass transition temperature is-45.74℃.The peel strength between the composite soft gel material and the inside of the mask could reach 0.307 N/10 mm,which is14 times higher than that of silicone gel.Through actual testing,the composite soft gel material could fit tightly to the wearer’s facial skin without causing discomfort while also adhering closely to the inside of the mask.(3)To quantitatively test the sealing performance of masks,a mask sealing testing device was built,and a mask sealing testing method and a virtual dust environment image particle recognition method were designed to detect and count the number of inhaled particles.The research showd that compared with not wearing a mask,sealing the mask on the model’s face with a pliable nose bridge and ear strap reduced the number of inhaled particles by 40%.After completely sealing the mask with double-sided foam tape and ear straps,the number of inhaled particles was reduced by 67% compared with the pliable nose bridge and ear strap seal.After sealing the mask with a homemade composite soft gel material,the mask’s sealing performance was significantly improved,increasing fourfold compared to not wearing a mask,three times compared to using a pliable nose bridge and ear strap seal,and twice compared to using sponge and silicone gel seal.It can be seen that the composite soft gel material prepared in this paper is suitable as a mask sealing material. |
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