The present invention relates to a structure in an article for personal care like diapers, training pants, absorbent underpants, adult incontinence products, bandages and feminine hygiene products, which can accept and distribute liquid.
Personal care articles include such items as diapers, training pants, feminine hygiene products such as sanitary napkins, panty-liners and tampons, incontinence garments and devices, bandages and the like. The most basic design of all such articles typically includes a bodyside liner, an outercover and an absorbent core disposed between the bodyside liner and the outercover.
Personal care products must accept fluids quickly and hold them to reduce the possibility of leakage outside the product. The product must be flexible and have a pleasing feel on the skin, and even after liquid insult, must not become tight or bind the user. Unfortunately, while previous products have met many of these criteria to varying degrees, a number have not.
It has been found that continuous flow insults in feminine hygiene products average 1 ml/hr and are not literally continuous or constant, but rather variable in rate and may even pause during a cycle. xe2x80x9cGush flowxe2x80x9d is defined as a sudden heavy flow condition and occurs at flow rates of up to 1 ml/sec. During a gush, 1-5 ml of fluid is released from the body onto the product. The term xe2x80x9ccontinuous flowxe2x80x9d is used to define any flow which falls outside of the definition of gush flow.
Combining continuous and gush flow conditions results in variable flow. Essentially, xe2x80x9cvariable flowxe2x80x9d is defined as continuous flow with intermittent gush flow occurrences. FIG. 1 illustrates the differences between variable flow (diamonds) and continuous flow (squares) over the life of a single product where flow rate volume is on the y-axis in g/hr and time is on the x-axis in hours.
The response to this problem is termed xe2x80x9cvariable flow managementxe2x80x9d and is defined as the ability to absorb and contain continuous and light flow (1-2 ml/hr) as well as multiple gushes or sudden heavy flow insults (1 ml/sec with a total volume of 1-5 ml) over the life of the product.
Many feminine care cover materials, for example, have low z-directional conductivity, low surface energy, low void volume, and provide little separation between the absorbent core and the user due to their two dimensional structure. Consequently, these covers result in slow and incomplete intake, high rewet, and large surface stains. In addition, typical intake or acquisition layers are low density, high void volume structures which are ideal for fast fluid intake, but because these structures typically have low capillarity, fluid is not adequately desorbed from the cover material, resulting in smearing and surface wetness. Materials which enhance cover desorption are typically high density, high capillarity materials, but because these materials have low void volume and low z-directional permeability, they inherently retard fluid intake.
There remains a need to address variable flow management by developing on an intake/distribution material which has the void volume necessary for fast intake and the high capillarity desired for sufficient cover desorption (i.e. surface dryness) while maintaining an appropriate capillary structure for fluid distribution.
An objective of this invention is, therefore, to provide such an intake/distribution material to manage a wide variety of flow conditions including sudden heavy flow insults, or gushes.
The objects of the invention are achieved by a airlaid fabric layer and spunbond nonwoven fabric transfer delay layer which have been joined by aperturing or xe2x80x9cco-aperturedxe2x80x9d. The result is improved multiple intake performance and a clean and dry cover surface during use in a feminine hygiene product. The material technology developments surrounding variable flow management focus on attaining the proper material structure and property balance necessary to achieve fast intake and improve cover desorption, cover staining, and rewet characteristics. These functional properties are provided through improved material technologies and product construction.