Development of baby diaper core structure
There are a variety of diaper products on the market, but they are mainly composed of four parts: skin-friendly surface layer, conductivity layer, absorption core, and a back layer. Among them, the absorption core is the most important structural component in diapers. As the main absorption layer, it is required to quickly absorb urine, and quickly diffuse urine into the whole absorption core by means of diversion and core suction. Then, the urine is rapidly absorbed and locked by super absorbent resin (SAP), and it does not reverse osmosis.
Development history of absorption core
In 1960, Procter & Gamble in the United States used nonwoven materials and wood pulp as an absorption core for diapers, which made diapers get certain applications.
In 1980, Japan Uni-Ca added SAP on the basis of the original absorption core, which made the diapers have certain liquid absorption and retention performance, and it was called the first generation of absorption core; However, there is neither stratification nor partition inside the absorption core, and uneven lumps will appear after liquid absorption, which will lead to obstruction of horizontal diffusion of urine, and excessive liquid absorption in a certain area, which will affect the reverse permeability of diapers
The second-generation absorption core makes a partition on the basis of the first generation absorption core, which can fix the villi pulp and SAP to a certain extent, and reduce the problem of the unsmooth lump after liquid absorption of diapers.
With the development of dry papermaking technology, namely dust-free paper technology, dust-free paper, porous fluffy nonwoven material, and SAP are combined to produce the third generation of absorption core, namely composite absorption core. The absorbing core is bonded by hot melt adhesive between each layer of material to make the diaper thinner. The absorption core contains a large amount of SAP, and the liquid absorption of diapers becomes larger; In addition, the grid structure of porous fluffy nonwoven material can fix SAP well, and the absorption core is uniform, and the overall expansion in the vertical and horizontal direction after the absorption makes the surface of diapers smoother.
At present, most domestic diapers use the third-generation absorption core.
The fourth-generation absorption core is further divided inside the third-generation absorption core, and better fixed the layers, the absorption core has become thinner, but the technology is still being perfected.
2 absorption core structure analysis
The absorption cores can be divided into traditional absorption cores and new composite absorption cores according to the different composite absorption modes.
The traditional villous pulp absorbs the core
The traditional absorption core is mainly composed of a coating layer, SAP, and villus. SAP and villus are mixed in a certain proportion to form SAP/villus absorbent. The coating layer is made of toilet paper or nonwoven material or multi-layer composite material. The upper coating layer should have the function of flow diversion and air permeability, and the lower coating layer should have the function of anti-seepage and barrier.
The structure of traditional villi - plasma core body
After urine is absorbed by the diaper with the traditional villus absorption core, the villus diffuses and transmits urine by virtue of its natural fiber advantages, while SAP rapidly absorbs, expands, and locks urine. SAP and villus pulp are loosely mixed in the absorption core, and there is enough space inside the absorption core for air permeability. Therefore, although the thickness of this diaper is relatively thick, the air permeability after liquid absorption is good. In addition, the villus pulp can fix SAP to a certain extent, prevent SAP from moving and accumulating, and keep the surface of diapers smooth and soft; In addition, the core suction effect of villi pulp can well solve the problem of gel blockage after SAP suction, weaken the phenomenon of glop after suction of diapers, and improve wearing comfort; But, in this kind of diapers, the wearer should avoid large mobile slip or flip in SAP, and caused the uneven distribution, SAP distribution areas more quickly and expansion and hinder the spread of urine, eventually lead to faults, too, influence of diapers fluid absorption for many times, more severe cases can cause surface film tear, urine leakage, Irritates the wearer's skin.
New composite absorption core
As diaper products become thinner and thinner, and people have higher and higher requirements for liquid absorption performance, new composite absorption cores continue to emerge. It usually covers dust-free paper and porous fluffy nonwovens with a coating layer, and then spreads SAP between the porous fluffy nonwovens, and then uses hot melt adhesive to bond the layers.
In a new type of composite absorbing core body, porous fluffy nonwoven material is one kind of hydrophilic material, the grid structure can be stored and fixed a lot of SAP and the SAP distributed evenly, so the new type of composite absorbing core body after absorbing the urine in the overall expansion, to avoid the fault appears after the absorption liquid and absorption core bodies too, diapers smoothness on the whole. At the same time, the diaper containing the new composite absorption core becomes very thin because the villus pulp is not added, and the wearers feel the lighter weight, and the amount of SAP added will increase accordingly, and the liquid absorption of the diaper will increase.
However, this absorption core also has some disadvantages. For example, without the support of villi pulp, SAP will form a gelatinous shape after absorbing urine, and the diaper feels hard and has poor air permeability. Hot melt adhesive is used between each layer of materials to fix SAP, while more SAP requires more hot melt adhesive, which will lead to harder hand feel, worse air permeability, affected liquid absorption speed, and heavy odor after liquid absorption; The ultra-thin composite absorption core generally has the defect that the first absorption speed is fast, and then the absorption speed decreases seriously, while the traditional villus pulp absorption core shows a relatively balanced absorption speed knot
With the continuous improvement of people's requirements for lightweight, breathable, absorbable, sanitary, and non-irritating diaper products, the absorption core of diapers will develop in the direction of functional diversification and integration, and the structure of the absorption core is constantly improving. Among them, the research on the structure of composite absorption core will make a new breakthrough in the field of hygiene products, which is conducive to grasping the needs of consumers, developing better new products, giving full play to the market potential of diapers in China, improving market penetration and expanding market share.
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