| With the emergence of infectious diseases such as HIV,hepatitis B virus and new coronavirus,prevention and control of nosocomial infection has become a top priority for curbing the spread of infectious diseases.In the prevention and control of hospital-acquired infection,there has been great progress in the personal protection and the isolation of hospital beds.However,the problem of cross infection caused by bedding contamination has not attracted people’s attention.At present,the beddings in the hospital are mainly made of low-cost cotton,while they have the disadvantages of easy to breed bacteria and easy to be contaminated by liquid carrying bacteria.Therefore,how to prepare a hydrophobic and moisture-permeable medical fabric capable of isolating bacteria and viruses is the key to the prevention and control of nosocomial infection.Waterproof and moisture permeable membranes are ideal raw materials for medical bedding fabrics and protective clothing.Its two main processing methods are as follows:(1)Porous PTFE membrane is compounded with substrates by hot pressing.(2)The surface of the substrates are treated with PTFE emulsion.The composite process and impregnation process have a great impact on its structure and performance,so how to prepare fabrics that meet the requirements of the prevention and control hospital infection through proper compounding and impregnation processes is a problem that needs to be solved urgently.Firstly,taking PTFE membrane with high hydrophobicity as the microporous layer,it was combined with PET/PA6 non-woven fabric and Tyvek respectively by hot pressing,and the effects of adhesives and hot-pressing process on the structure and properties of the composite membranes were investigated.Then PET/PA6 non-woven fabric,Tyvek and bacterial cellulose membrane(BC)were surface treated by emulsion dipping method,and the influence of the dipping process on the properties of the modified membranes was studied.The feasibility of the application of the waterproof and moisture permeable membranes obtained by the two processes in hospital beddings was explored.The main research contents and conclusions are as follows:(I)Hot pressing methodThree-layer composite membranes using PTFE membrane as the microporous layer,PET/PA6 non-woven fabric and Tyvek as substrates were prepared by hot pressing with thermoplastic polyurethane elastomer rubber(TPU)as the adhesive.The results show that:(1)When PET/PA6 non-woven fabric is used as the substrate and the temperature is increased from110℃to 130℃,due to a decrease in viscosity of TPU melts,the blocking degree of the TPU melt on the pore structure of the composite membrane increases,resulting in the decrease of the average pore diameter and pore density of the composite membrane,which makes the moisture permeability of the composite membrane decrease and the peel strength of it increase.When the temperature is constant at 120℃and the pressure is increased to 10MPa,the molten TPU seriously blocks the holes of the membrane,affecting the moisture permeability of the composite membrane but improving the peel strength of it.(2)When Tyvek is used as the substrate,in addition to the influence of TPU,the partial melting of Tyvek(HDPE)itself also affects the microporous structure of the PTFE membrane,which effects the moisture permeability and peel strength of the composite membrane.When the pressure is 5MPa,the moisture permeability and peel strength of the composite membrane are 138g/(m~2×h)and 2.72cN/mm respectively at 110℃.When the temperature reaches 130℃,the simultaneous melting of Tyvek and TPU increases the degree of blockage of the pores,and the moisture permeability of the composite membrane is105g/(m~2×h),a decrease of 23.9%.When the temperature is 120℃and the pressure increases to10MPa,the moisture permeability further of its decreases while the peel strength further increases.(2)In order to avoid the influence of TPU on the pore structure,two composition membranes were prepared without using TPU.The results show that:When PET/PA6 non-woven fabric is used as the subtrate and the temperature increases from 240℃to 260℃,since the melt formed after partial melting of the substrate increases the degree of blockage of the microporous layer,the moisture permeability of the composite membrane tends to decrease,but the peel strength tends of it to increase.When the temperature is 240℃and the pressure is increased from5MPa to 10MPa,the PET/PA6 blend melt severely blocks the pore structure of the composite membrane,causing the average pore diameter and pore density of the composite membrane to decrease,affecting the moisture permeability of composite membrane but improving the peel strength of it.(2)When Tyvek is used as the substrate and the pressure is 5MPa,the moisture permeability of the composite membrane is 143g/(m~2×h)at 135℃.When the temperature rises to145℃,the degree of clogging of the pores of the membrane caused by the molten Tyvek increases,and the moisture permeability of the composite membrane is 87.3g/(m~2×h),a decrease of 38.9%.When the temperature is constant at 140℃and the pressure is increased to 10 MPa,the moisture permeability of the composite membrane decreases but its peel strength increases.(II)Dipping methodPTFE emulsion was used as the impregnating solution for the surface treatment of PET/PA6 non-woven fabric,Tyvek and BC.The results show that:(1)When the concentration of the impregnating solution is 20wt%,with the increase of the impregnation time,the amount of PTFE coating of the substrates gradually increased and tended to be stable at the later stage.The coating amount of the substrates is directly related to the surface characteristics and pore structure of them.The order of the three base membranes from strong to weak is:BC>PET/PA6non-woven fabric>Tyvek,and their average pore size from large to small order is:PET/PA6non-woven fabric>BC>Tyvek.As a result,the coating amount of PET/PA6 non-woven fabric is the largest,followed by BC and Tyvek is the smallest.The increase in the coating amount,on the one hand,causes the degree of the base film surface to be wrapped by the PTFE film to increase,so that the rolling angle of the base film after treatment decreases;on the other hand,the degree of pore blockage of the basement membrane increases,which affects the moisture permeability of the substrates.(2)When the immersion time is 15 min,with the increase of the concentration of the immersion solution,PTFE coating amount of the substrates increases almost linearly.Because The order of increasing the coating amount of the three substrates from small to large is:PET/PA6non-woven fabric>BC>Tyvek,the surface-treated PET/PA6 non-woven fabric has the largest change in moisture permeability and rolling angle,followed by BC,and the properties of Tyvek after surface treatment with PTFE emulsion have the smallest change. |
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