The Study On The Relationship Between Structure And Absorbility Of Baby Diapers

With the improvement of people’s living standard, baby diapers have become more and morepopular. Though there are many advantages on the use of diapers, it may form a moistenvironment after wearing for a long time, especially in rural areas where changing frequency ofdiapers is very low. When babies’ skin is under a moist environment for a long time, it may causeskin dieases or diaper rash. Therefore, the absorbility of diapers needs to be improved to get aproduct having excellent long-term performance.In this study, Several common diapers were selected from the market, and they werenumbered form1#to6#, then through dismantling the diapers, basic information of their mainstructures was acquired, which include surface, acquisition distribution layer(ADL), absorbentcore and impervious bottom film. Then tests have been taken on the diapers, and analysis has beenmade on the test difference according to the different structures. Based on the analysis result,several ADLs with special structures have been designed, they were numbered form1*to3*.Finally, the designed ADL materials have been put into diapers, and then their application effectshave been evaluated, the self-made diapers wre numbered form A to C. Based on the experimentsand analysis researches, this thesis has got the following conclusions.(1) ES fiber is mostly used in the surface nonwoven materials with thermal bondingtechnology, the surface density is usually between18～30g/m2, the thickness is usually below0.5mm, and recently three-dimensional surface materials have gained popularity. ES fiber is alsowidely used in the ADL materals with hot wind technology, the width is ranged between7～9cm,the length is usually between16～24cm, the areal density is30～45g/m2, and the thickness is0.5～1mm. The absorption core layer is mostly made by SAP and fluff pulp’s mixture with bumfpacked. The SAP granules are distributed among fluff pulps randomly. The SAP content of thecores are all above15%, among which the4#diaper is highest, as much as45%. The imperviousbottom films were mostly consisted of PP hot-rolled nonwoven materials and PE breathablemicroporous membrane, the largest aperture of the membranes is below4μm, which is smallerthan the smallest aperture of water-drop. Therefore, all the membranes have the function of water resistible and breathable.(2) All the diapers have excellent absorbility,25～35times deionized water and10～13times artificial urine of their self-weights can be absorbed by them. Among them, the4#diaperhas the best absorbility, as much as34.22times deionized water and12.27times artificial urine oftheir self-weights can be absorbed by it. The3#diaper has the lowest wetback and the shortestpenetration time, when penetrating by artificial urine for four times, the wetback is9.27g and thepenetration time is14.57s. The4#diaper has the best diffusion performance, when penetrating byartificial urine for four times, the ratio between its back diffusion length and surface diffusionlength is0.92.(3) Several composite ADL materials has been designed in this paper, the upper layer of theADL is a parallel fiber web made by ES fibers, and the under layer of the ADL is a mixed fiberweb made by viscose and polyester, the webs are consolidated by thermal bonding technology andchemical bonding technology. According to the different ratio of viscose and polyester in theunder layer, there are three kinds of ADL materials. Through the properties test, it shows that withthe increase of viscose ratio, the thickness, MD/CD value, penetration time and diversion lengthdecreased, but the absorbency and retentive liquid power increased. The2*ADL, in which theratio of viscose and polyester is70/30, has been balanced between the absorbency and retainliquid ability, and a high ratio (10.02) between the absorbency and retentive liquid power has beengotten, thus the temporary liquid storing ability is regarded as the best.(4) Compared with the diapers bought from the market, the self-assembled diapers havebetter performance in wetback, when penetrating by artificial urine for four times, the largestinfiltration liquid amount is3.67g, which was50%lower. The self-made diapers’ ratio betweenthe back diffusion length and surface diffusion length is higher than the original ones, reached upto0.97. The penetration time of the self-made diapers have decreased largely, the time of thediaper C is as short as9.25s when being penetrated by artificial urine for four times.According to the experiments and analyses, we can summarize that, diapers withthree-dimensional surface materials, ADL materials having a high balance between thelongitudinal diffusion and the vertical permeability, absorption core layers with excellentabsorbility, may have the properties of low wetback, great absorbility, high absorbing speed andgood diffusion ability when being used for a long time.