Preparation And Properties Of Nonwoven Materials Loaded With Tea Polyphenols

In 2020,the outbreak of the new crown epidemic triggered a worldwide health crisis.Affected by the epidemic,people are paying more and more attention to environmental hygiene and self-care.In life,people will come into contact with various bacteria,fungi and other microorganisms.Bacteria growing on textiles will not only cause discoloration,mildew,embrittlement and degradation of fiber products,but also cause strange irritation to human skin and induce various skin diseases,which affect human health.Therefore,the development of antibacterial textiles will become the focus of long-term attention in the textile industry.Tea polyphenol(TP)is a safe and harmless natural antibacterial agent and natural dye.It has substantial hydroxyl groups in its structure and has biological activities such as anti-oxidation,antibacterial,anti-mildew,and deodorizing.Among many non-petroleum-based materials,polylactic acid(PLA)is a non-petroleum-based material with favorable properties and extensive research.Therefore,the development of natural antibacterial agents and biodegradable substrates has greater development prospects and necessity in the preparation of antibacterial textiles.In this paper,viscose(R)spunlace and polylactic acid spunbond nonwoven materials are used as substrates,and natural antibacterial agent TP is selected to prepare antibacterial nonwoven materials loaded with tea polyphenols.First,discuss the influence of pad dyeing craft parametric on the dyeing properties of viscose nonwoven materials.The structure and properties of TP-loaded viscose(denoted as R-TP)and polylactic acid(PLA-TP)nonwoven materials are analyzed.Secondly,in order to improve the dyeing performance of PLA fibers by tea polyphenols,two hydrophilic modification methods of PLA fibers are proposed.Moreover,analyze from the surface morphology,composition and property of the material.The best process for dyeing viscose spunlace nonwovens on tea polyphenols.First,put the viscose non-woven material into a p H=6,4%TP solution,and dye it at a constant temperature of 40 °C for 15 minutes.Then,adopt the padding method(85-90% rolling reduction),and bake at 120 °C for 2 minutes.Finally,after washing with water,it is dried to obtain R-TP nonwoven material.The structure analysis of R-TP and PLA-TP nonwoven materials can be known.TP and viscose fiber are combined with van der Waals force or hydrogen bond,and successfully adsorbed on viscose fiber.The prepared R-TP nonwoven material is darker and evenly dyed,showing a brownish yellow color.It has a certain p H responsiveness,showing light brown in acidic conditions,brownish yellow in neutral or alkaline conditions.It has a good antibacterial effect,with a bacteriostatic rate of 89.6%against E.coli and 92.5% against Staphylococcus aureus.After washing 15 times,even if the viscose non-woven material is entangled and holes appear,the color fastness rating can still reach 3-4.However,there are no active groups in the PLA fiber structure,and the capability to combine to TP is poor,and only a few tea polyphenols are dyed on the PLA fiber.Therefore,PLA-TP nonwoven material has lighter color and uneven dyeing.The p H value has no obvious color change to PLA-TP nonwoven material,In addition,the antibacterial effect is poor,with an inhibitory rate of 31.7% for E.coli and 34.0% for S.aureus.In order to improve the adsorption capacity of PLA fiber to tea polyphenol dyes,it is proposed to use dopamine(DA)to modify its surface hydrophilic.Combined with the analysis of the morphology and structure of the PLA-PDA-TP nonwoven material,it can be seen that the polydopamine(PDA)formed by the oxidative polymerization of DA successfully deposited on the surface of the PLA fiber and was evenly distributed.Then through the hydrogen bonding force,the tea polyphenols are adsorbed,and the load is bound to the PLA fiber.Polydopamine coating introduces a large number of active groups on the surface of PLA fiber,which greatly improves the hydrophilicity and moisture absorption of the fiber.This is conducive to the adsorption of water-soluble dye tea polyphenols by PLA fiber.The water contact angle of the prepared PLA-PDA-TP nonwoven material is 0° within2 s,and the gross effect value is 11.45 cm.After 15 frequency of washing with water,the CA is still 0°,maintaining good hydrophilic properties.Compared with the PLA-TP nonwoven material,the antibacterial effect of PLA-PDA-TP nonwoven material is obviously enhanced,the antibacterial rate of E.coli is 90.9%,and the antibacterial rate of S.aureus is 92.7%.Moreover,the washing fastness is good,washing 20 times,the antibacterial rate of the two strains can still reach more than 70%.Based on the influence of polydopamine's own color,it not only fails to reflect the p H response effect of PLA-PDA-TP nonwoven materials,but also limits its application in printing and dyeing.Therefore,it is further proposed to use acrylic acid to modify the surface of PLA fibers to give PLA nonwoven materials more functionality.First,acrylic acid polymerized under the action of initiator and emulsifier.Then it is cross-linked and combined with the crosslinker EGDMA to prepare PLA-COOH nonwoven material.Finally,the adsorbed and loaded tea polyphenols are co-attached to PLA fibers.PLA-COOH nonwoven material has good hydrophilicity,and the dye uptake rate of tea polyphenol dyes is increased to 42.5%.The PLA-COOH-TP nonwoven material loaded with tea polyphenols has further improved hydrophilicity and hygroscopicity.The CA immediately after contact with water droplets is 0°,and the gross effect value is 13.7 cm.The antibacterial effect is improved,the inhibition rate E.coli is 90.4%,and the antibacterial rate for S.aureus is 93.6%.After 20 washings,the inhibitory rate of the two strains can still reach more than 73%.The color fastness is high,and the discoloration rating result is 4 grades after washing 50 times.And endow the PLA-COOH-TP non-woven material with a certain p H responsiveness,which can present different colors in environments with different p H values.The nonwoven material is light brown or dark brown in acid,and brown in neutral or alkaline.