JP3245177B2 - Absorbent products with liquid contact angle gradient - Google Patents

Description

Description: FIELD OF THE INVENTION The present invention relates to an absorbent product, in particular a breathable backsheet that reduces the passage of liquid onto the user's underwear.
sanitary napkin having an acksheet).

BACKGROUND OF THE INVENTION The primary consumer demand for development in the field of absorbent products, especially sanitary products, is a high level of protection and comfort.

One of the highly desirable means of improving the comfort of an absorbent product is the so-called "breathable backsheet"
Is to use. Breathable backsheets are made of an apertured film that is directed to the movement of liquids, such as disclosed in US Pat. No. 4,591,523.
rmed film). Such perforated backsheets are typically permeable to steam and air, and allow for gas exchange with the surroundings. Thereby, a part of the liquid accumulated in the core is evaporated, and the air circulation inside the absorbent product is increased. This is very beneficial as the sticky feel experienced by many of the wearers during use, especially during prolonged use, is reduced.

However, a major drawback associated with the use of breathable backsheets in absorbent products is the increased likelihood of leakage, usually manifested as permeation of liquid onto the user's underwear. In principle, such breathable backsheets allow only gaseous material to permeate and move liquids in only one direction, but do not allow for physical leakage, such as pressure extrusion, diffusion, and capillary action. Such a mechanism can also occur, and the liquid travels in the opposite direction through the backsheet and reaches the user's underwear. These mechanisms are even more pronounced when using the product, especially when moving the body vigorously, when excreting is high, or when using the product for an extended period of time.
In other words, the breathable backsheet is excellent in improving comfort, but causes unacceptable inconvenience, particularly in protection under a heavy load.

The problem of incorporating a breathable backsheet into an absorbent product to allow liquid to permeate over the user's underwear has been recognized in the art. Attempts to solve this problem have primarily involved the use of multilayer backsheets as shown in U.S. Pat. No. 4,341,216. Similarly, the unpublished European Patent Application No. 94203230 discloses that at least two
A breathable absorbent product comprising a breathable backsheet comprising two breathable layers is disclosed. Unpublished European Patent Application No. 94203228 also includes an outer layer comprising a gas permeable, hydrophobic, polymeric fibrous fabric and an inner layer comprising a perforated molded film having directionality for liquid transport. The invention discloses a breathable backsheet for disposable absorbent products.

Alternatively, another solution presented to this problem is achieved by increasing the thickness of the absorbent product, usually by increasing the thickness of the core to ensure the desired level of protection. .

However, it has been found that none of the above solutions are entirely satisfactory. This is especially true for thin products, as thickness is also considered to be a major factor affecting product comfort. Thus, although there are two methods available for making absorbent products with increased comfort, thin breathable products do not provide the desired level of protection.

As a result, there is a need to provide an absorbent product that has improved comfort by utilizing a breathable backsheet and that has the required level of protection despite having a reduced thickness.

Using a breathable back sheet on a thin sanitary napkin,
It has been found that it can provide a high level of protection and comfort at the same time, but this creates a gradient of hydrophobicity between the backsheet and the core, and low surface energy materials such as silicone and chlorofluorocarbon or This is achieved by using a low surface energy treatment.
By such methods, physical mechanisms such as diffusion and capillary action are hindered, and even if not completely eliminated, the passage of liquid is expected to be reduced considerably.

A further advantage of the present invention is that it is possible to provide a breathable backsheet coated with a hydrophobic material, so that it is no longer necessary to synthesize the whole layer, it can be at least partially natural It is. This provides a significant and significant benefit to the consumer as the natural feel is imparted to the product.

The use of surface energy gradients per se is discussed in unpublished US patent application Ser. No. 08 / 442,935. This discloses a liquid transport web (eg, a topsheet) that provides a surface energy gradient. The web facilitates transport of the liquid in one direction and prevents transport in the opposite direction. The web has a first surface and a second surface separated from each other by an intermediate portion. The first surface of the web is
It has a lower surface energy compared to the intermediate surface energy, thereby creating a surface energy gradient. Suitable low surface energy materials include silicone, fluoropolymer and paraffin. The web is particularly suitable as a topsheet for absorbent products and transports liquid into the absorbent structure away from surfaces in contact with the wearer.

SUMMARY OF THE INVENTION A first aspect of the present invention relates to a disposable absorbent product comprising a liquid permeable topsheet, an absorbent core, and a backsheet. The core is located between the topsheet and the backsheet. The backsheet comprises a liquid-permeable polymeric film that moves liquid unidirectionally toward the core, the core comprises a liquid storage layer, and the backsheet comprises an outer layer. . The core and the backsheet each comprise at least one layer, each layer having a wearer side surface and a garment side surface, each surface of these layers having a liquid contact angle. The absorbent product extends from the garment-side surface of the liquid-retaining layer and includes the garment-side surface of the liquid-retaining layer, the garment-side surface of the outer layer, the garment-side surface of the outer layer, and the garment of the liquid-storage layer A lower portion having a side surface and a portion located between the outer layer and the garment side surface. The invention is characterized in that the wearer side surface of at least one layer in the lower part has a liquid contact angle greater than the liquid contact angle of the adjacent garment side surface of the adjacent layer.

A second aspect of the invention relates to the situation where the garment-side surface of at least one layer in the lower part has a liquid contact angle greater than the liquid contact angle of the wearer-side surface of the same layer.

A further aspect of the invention relates to a method for producing an absorbent product as described above, comprising applying a low surface energy material to the surface of at least one layer in the lower part.

Another aspect of the invention relates to a method for manufacturing an absorbent product as described above, comprising the step of incorporating a low surface energy material into one of the layers in the bottom.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view, partially cut away to show the configuration, of a first embodiment of the absorbent product of the present invention.

FIG. 2: an enlarged sectional view of the backsheet of the present invention, taken along line II of FIG.

FIG. 3: An enlarged cross-sectional view of a droplet on a surface, where the angle A indicates the contact angle between the liquid and the surface.

Figure 4: Two different surface energies, and thus two
FIG. 3 is an enlarged cross-sectional view of a droplet on a surface showing two different contact angles A (a) and A (b).

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sanitary napkin (1), a baby diaper,
It relates to disposable absorbent products such as incontinence products and panty liners. Typically, such products are
Liquid permeable topsheet (2), backsheet (3),
And an absorbent core (4) present between the topsheet (2) and the backsheet (3). The top sheet (2), the back sheet (3) and the core (4)
Each has a wearer side surface and a clothes side surface. The garment-side surface of the topsheet and the wearer-side surface of the backsheet are joined together at the end (5) of the absorbent product. In a preferred embodiment of the invention, the absorbent product comprises a wing, side wrapping elem.
ent), or side flaps.

Absorbent core According to the present invention, the absorbent core comprises a first part and a second part. The first part comprises the following components:
(A) an optional first liquid distribution layer, preferably with an optional second liquid distribution layer; (b) a liquid storage layer; and (c) an optional fiber ("dusting") layer underlying the storage layer. And (d) other optional components.

According to the invention, the absorbent core can have any thickness, depending on the end use envisaged. In a preferred embodiment of the invention, wherein the absorbent product is a sanitary napkin or panty liner, the thickness of the core is between 15 and 1 mm, preferably between 10 and 1 mm, most preferably between 7 and 1 mm.

a first / second liquid distribution layer One of the optional components of the first part of the absorbent core according to the invention is a first liquid distribution layer and a second liquid distribution layer. Typically, the first liquid distribution layer is located below the topsheet, where the transfer of liquid takes place. The liquid received by the topsheet is transported to the first distribution layer and is finally distributed to the storage layer. This movement of liquid through the first distribution layer occurs not only in the thickness direction of the absorbent product, but also in the length and width directions. Is also optional,
The preferred second distribution layer is typically below the first distribution layer, where the transfer of liquid takes place. The purpose of the second distribution layer is to receive the liquid immediately from the first distribution layer and to quickly transfer the liquid to the underlying storage layer.
This ensures that the liquid storage capacity of the underlying storage layer is fully utilized. The liquid distribution layer can be composed of any material typical for such distribution layers.

b Liquid Reserving Layer The liquid retaining layer (6) is arranged to receive and receive liquid, and typically exists below the first distribution layer and the second distribution layer. The liquid storage layer may be composed of any common absorbent material or a combination thereof. Preferably, absorbent gelling materia (absorbent gelling materia) usually referred to as "hydrogel", "superabsorbent", "hydrocolloid" material
l) with a suitable carrier.

The absorbent gelling material can absorb a large amount of aqueous bodily fluid, and can retain such absorbed liquid under a weak pressure. The absorbent gelling material can be uniformly or heterogeneously dispersed in a suitable carrier. If the appropriate carrier is itself absorbent, it can be used alone.

Absorbent gel materials suitable for use herein are often composed of slightly cross-linked, partially neutralized polymeric gel materials that are poorly soluble in water. Upon contact with water, the material forms a hydrogel. Such polymeric materials are polymerizable, well known in the art,
It can be prepared from unsaturated, acid-containing monomers.

Suitable carriers include fluff and / or tissue natural fibers, modified or synthetic fibers,
Materials commonly used for absorbent structures are included, such as, inter alia, modified or unmodified cellulose fibers. Suitable carriers can be used with the absorbent gelling material,
They can be used alone or in combination. For sanitary napkins and panty liners, tissue or tissue laminate
Is most preferred.

Embodiments of absorbent structures made in accordance with the present invention include:
It comprises a double layer tissue laminate formed by folding the tissue on itself. These layers can be joined to one another, for example by means of an adhesive or by mechanical interlocking or by hydrogen crosslinking. An absorbent gel material or other optional material is included between the layers.

Modified cellulose fibers, such as stiffened cellulose fibers, can also be used. Synthetic fibers can also be used, such as cellulose acetate, polyvinyl fluoride, polyvinylidene chloride, acrylics (Orlon
Etc.), polyvinyl acetic acid, insoluble polyvinyl alcohol, polyethylene, polypropylene, polyamide (Nylo
n), polyester, bicomponent fib
er) Includes those made from ternary fibers, mixtures thereof, and the like. Preferably, the fiber surface is hydrophilic or has been treated to be hydrophilic. To improve the retention of liquid, the storage layer is made of perlite (Perl).
ite), diatomaceous earth, vermiculite, and the like, and may also contain a filler material.

If the absorbent gelling material is unevenly dispersed in the carrier, the retaining layer can be locally uniform. That is,
Within the dimensions of the storage layer, it has a distribution gradient in one or several directions. Non-uniform distribution may also occur in a laminate of a carrier that partially or completely encapsulates the absorbent gelling material.

c Optional fiber ("dusting") layer An optional component for inclusion in the absorbent core of the present invention is a fiber layer adjacent to and typically underlying the storage layer. The underlying fiber layer is typically referred to as a "dusting" layer, as it provides a substrate for placing the absorbent gelling material in the storage layer during manufacture of the absorbent core. In fact, the absorbent gel material is made of fibers, sheets,
Or when in the form of a macrostructure, such as a thin strip, it is not necessary to include the fiber "dusting" layer. However, the "dusting" layer quickly sucks up liquid along the long axis of the pad (wickin).
g) to provide some additional liquid handling capacity.

d Other Optional Components of Absorbent Structure The absorbent core of the present invention may include other optional components normally present in absorbent webs. For example, a reinforcing scrim can be located within or between each layer of the absorbent core. Such a reinforcing scrim must be positioned so as not to be an interfacial barrier to liquid movement. A reinforcing scrim is not usually required for thermally bonded absorbent structures, as the thermal bonding usually provides structural integrity.

Another component, which may be included in the absorbent core of the present invention and is preferably provided near or as part of the first or second liquid distribution layer, is a odor modifier.
rol agent). Activated carbon coated or added with other odor modifiers, especially suitable zeolite or clay materials, are optionally incorporated into the absorbent structure. These components can be incorporated in any desired form, but are often included as discrete microparticles.

Topsheet The topsheet (21) may comprise a single layer or multiple layers. In a preferred embodiment, the topsheet is
A first layer (22) forming the wearer side surface of the topsheet, and a second layer (23) between the first layer and the absorbent structure / core
Is provided.

The topsheet (21) as a whole (and therefore each layer as well) should be compliant, soft to the touch and non-irritating to the wearer's skin. Further, the topsheet may be resilient so that it can extend in one or two directions. According to the present invention, the topsheet can be utilized for such purpose and may be made from any material known in the art, such as non-woven fabric, film or a combination of both. In a preferred embodiment of the present invention, at least one layer (preferably the top layer) of the topsheet comprises a liquid permeable porous polymeric film (2).
2).

Preferably, for example, U.S. Pat.No. 3,929,135, U.S. Pat.No. 4,151,240, U.S. Pat.
No. 4,324,426, U.S. Pat.No. 4,343,314 and U.S. Pat.
As detailed in US Pat. No. 4,591,523, the top layer is made of a film stock having holes provided to facilitate the transfer of liquid from the wearer side surface to the absorbent structure.

Typically, the topsheet extends throughout the absorbent structure and may extend into and form part or all of a suitable side flap, side wrapping element or wing.

Backsheet The absorbent product of the present invention comprises a breathable backsheet (24) for transporting liquid in one direction. The primary role of the backsheet is to ensure that extrudes absorbed and contained in the absorbent structure do not wet products in contact with absorbent articles such as underpants, pants, pajamas and underwear. It is to be. But other,
Since the backsheet of the absorbent product of the present invention allows both steam and air to pass through, air can be circulated into and out of the backsheet.

As used herein, the term "one-way" means a material that at least substantially, if not completely, transports liquid unidirectionally toward the core. The directionality of the liquid may be determined using Test Method 3 as detailed in the test methods herein.

According to the invention, preferably the backsheet comprises at least two layers, a first layer comprising a gas-permeable porous polymeric film (25) and a gas-permeable fibrous fabric layer (26). And a second layer. Preferably, said first and second layers have a similar relative void volume.
The first layer is typically located adjacent to the core (27), and subsequent backsheet layers are typically further away from the core. On the back sheet,
Further, a layer may be included. In all cases, the outermost layer furthest from the core is the outer layer. All layers of the backsheet can be in direct contact with each other substantially intimately.

The perforated first layer of the backsheet (25) comprises a layer having discontinuous holes (28) extending in the direction of the core beyond the horizontal plane of the garment side of the layer; Thus, a projection (29) is formed. Each projection has an opening at its end. The projections preferably have a funnel or conical shape, similar to that described in US Pat. No. 3,929,135. The holes located in the plane of the layer and the openings located at the ends of the projections themselves can be circular or non-circular. In either case, the size or area of the cross section of the opening at the end of the protrusion is smaller than the size or area of the cross section of the hole located in the plane of the layer. The first layer of the backsheet typically has an open area of more than 5% of the total film layer area, preferably 10 to 35%.
Having. The interstitial area of the layer can be determined using Test Method 4 as detailed in the Test Methods herein.

According to the present invention, said first layer of the backsheet (25) can be made from any material known in the art, but is preferably made from commonly used polymeric materials.

The second layer of the backsheet comprises a gas permeable fibrous fabric layer (26) composed of polymeric fibers, such as a polymeric non-woven fabric. The fibrous fiber layer preferably basis weight of 10 to 100 g / m ^2, more preferably 1
Having a basis weight of 5 to 30 g / m ^2. The fibers can be made from any polymeric material, especially polyethylene, polypropylene, polyester polyacetate or combinations thereof (inter- and intra-fiber combinations), such as synthetic and non-absorbable natural fibers or cotton. Mixed fibers of treated natural fibers may be used. The fibers are preferably spunbonded bloons.
wn), a carded blown or melt blown. Preferably, the second layer comprises a spunbond blown matrix coated on one side with meltblown fibers, or a meltblown fiber coated on both sides with spunblown fibers.
The second layer of the backsheet may further comprise at least 5% of the weight of the liquid-absorbing fibrous layer such that it swells and reduces the space between fibers.

The backsheet typically extends throughout the absorbent structure and extends over or forms part or all of a suitable side flap, side wrapping element or wing.

Liquid Contact Angle According to a first aspect of the invention, every layer in the lower part has a wearer side surface and a garment side surface, each surface having a liquid contact angle, wherein the lower part The wearer side surface of at least one of the layers has a liquid contact angle that is greater than the liquid contact angle of the garment side surface of the adjacent garment side surface of the adjacent layer.

According to a second aspect of the invention, every layer in the lower part has a wearer side surface and a garment side surface, wherein each said surface of the layer has a liquid contact angle, wherein the At least one garment-side surface of the layer in the lower portion has a liquid contact angle that is greater than a liquid contact angle of a wearer-side surface of the same layer.

As a rule, the gradient of the contact angle is in the lower part,
It can be between any layers (wearer side or garment side) in any surface therein. Thus, the gradient of the liquid contact angle may be present across the wearer side and the garment side surface of the same layer, or a layer adjacent to the garment side surface of at least one of the lower middle layers. Between the adjacent surfaces of the backsheet, i.e., between the wearer-side surface of the first layer of the backsheet and the garment-side surface; Between the wearer side and the garment side surface of the second layer of the backsheet, or any subsequent backsheet layer. It is further expected that the combination of these layers, each exhibiting a particular contact angle relationship, will provide a continuous contact angle gradient at the bottom.

However, for simplicity, the following description of the invention will focus on the presence of different or increasing contact angle gradients between the garment-side surface of the core and the wearer-side surface of the first layer of the backsheet. .

Typically, a drop of liquid 110 placed on a solid surface 112
Makes an angle A with the solid surface, as seen in FIG.
As the wettability of the solid surface with the liquid increases, the contact angle A decreases. As the wettability of the solid surface with the liquid decreases, the contact angle A increases. The liquid-solid contact angle is measured by Arthur W. Adamson (1967) Physical
Chemistry of Surfaces, Second edition, FEBartell
And HH Zuidema, J. Am. Chem. Soc., 58, 1449 (193
6), JJ Bikerman's Ind.Eng.Chem., Anal.Ed., 13,443
(1941) can be determined by techniques known in the art, as described in more detail, each of which is incorporated herein by reference. More recent literature in the field includes Cheng et al., Colloids and Surfaces
43: 151-167 (1990), and Rotenberg et al.
f Colloid and Interface Science 93 (1): 169-183
(1983), which are also incorporated herein by reference.

As used herein, the term "hydrophilic" is used for a surface that can be wetted by an aqueous liquid placed thereon (eg, an aqueous body fluid). Hydrophilicity and wettability are typically defined by the contact angle and the surface tension of the liquid and solid surfaces involved. This means that
Angle, Wetability and Adhesion, Robert FG
American Chemi edited by ould (copyright 1964)
detailed discussion in the cal Societypublication,
Incorporated herein by reference. An aqueous liquid (hydrophilic) wets the surface when the liquid tries to spread naturally across the surface. Conversely, a surface is considered to be "hydrophobic" unless the aqueous liquid attempts to spread naturally across the surface.

The liquid / solid contact angle depends on the surface non-uniformity (eg, chemical and physical properties such as roughness), contamination, chemical / physical treatment or composition of the solid surface as well as the properties of the liquid and the properties of the liquid. Depends on pollution. The surface energy of the solid also affects the contact angle. As the surface energy of the solid decreases, the contact angle increases. As the surface energy of the solid increases, the contact angle decreases.

The energy required to separate a liquid from a solid surface (eg, a film or fiber) is described by equation (1).

(1) W = G (1 + CosA) where W is the adhesion work measured in erg / cm ² (× 10 ⁻³ Jm ⁻² ), and G is dyne / cm (× 10 ³ Nm ⁻¹ ). A is the measured surface tension of the liquid, and A is the liquid-solid contact angle measured in degrees.

For a given liquid, the work of deposition increases with the cosine of the liquid-solid contact angle (maximum at zero contact angle).

The work of deposition is one of the useful tools for understanding and quantifying the surface energy properties of a particular surface for a particular liquid.

Table 1 is useful for demonstrating the relationship between the liquid-solid contact angle and the work of adhesion for a particular liquid (eg, water), whose surface tension is 75 dynes / cm (75 × 10 ⁻³ Jm ^{−). 2} ).

As shown in Table 1, as the work of deposition of a surface decreases (as the surface energy of a surface decreases), the liquid contact angle on the surface increases, so that the liquid is "droplet""Beadup" and occupy less contact surface area. Similarly, the converse is also true: with a particular liquid, the surface energy of a particular surface decreases. Therefore, the work of deposition affects the interfacial liquid phenomenon on the solid surface.

In the context of the present invention, and more importantly, it can be seen that the surface energy gradient exhibited by the liquid contact angle or discontinuity is useful in preventing liquid transport. FIG. 4 illustrates a droplet 110 present on a solid surface having two regions 113 and 115 having different surface energies (shown with different hatches for clarity).
Is shown. In the state shown in FIG.
Shows a lower surface energy than the region 115, and therefore has less wettability by the droplets than the region 115. Thus, the droplet 110 produces a contact angle A (b) at the edge of the droplet contacting the region 113, which occurs at the edge of the droplet contacting the region 115. Larger than). For clarity, points "a" and "b" are on a plane, but the distance "dx" between points "a" and "b" need not be a straight line, but Irrespective of the surface shape,
Note that it represents the degree of droplet / surface contact. Thus, the droplet 110 experiences an external force resulting from the unbalanced surface energy and thereby the relative surface energy difference between the regions 113 and 115 (i.e., the surface energy gradient or discontinuity). Can be represented by equation (2).

(2) df = G [cosA (a) -cosA (b)] dx where dF is the net force on the droplet dx is the distance between reference positions "a" and "b" G is defined previously As described above, A (a) and A (b) are the contact angles at positions “a” and “b”, respectively.

Expression (1) is represented by cosA (a) and cosA (b) and is substituted into expression (2) to obtain expression (3): (3) dF = G [(W (a) / G-1)-((W (b) / G-1)) dx is obtained.

 Equation (3) can be simplified to equation (4) (4) dF = (W (a) -W (b)) dx.

The importance of the difference in surface energy between the two surfaces is clearly shown in equation (4) since varying the magnitude of the difference in the work of bonding has a direct proportional effect on the magnitude of the force. ing.

The physical properties of surface energy effects and capillarity are
"Textile Scienc" edited by Portony K. Chatterjee (1985)
e and Technology, Volume 7, Absorbency '' and AMSc
hwartz's `` Capillarity, Theory and Practice, Ind.Eng.
Chem. 61, 10 (1969) ". These are incorporated herein by reference.

Thus, the force experienced by the droplet moves to the surface with the higher surface energy, in this case the core. Simplify,
For clarity, the surface energy gradient or discontinuity is depicted in FIG. 4 as a simple and clear discontinuity, ie, a boundary between regions that are uniform and well-defined but have different surface energies. Have been. The force acting on any droplet (or part of such a droplet) is determined by the surface energy of each area that the droplet contacts, the gradient of the surface energy being a continuous gradient or a gradual gradient. May exist as.

As used herein, the term "gradient" when used in reference to a difference in surface energy or work of attachment is intended to mean a change in surface energy or work of attachment that occurs over a measurable distance. The term "discontinuity" is intended to mean a type or transition of "gradient" and refers to any change in surface energy between substantially zero distance. Therefore,
All “discontinuities” as used herein will be included in the definition of “slope”.

Also, the terms "capillary" and "capillarity" as used herein refer to the principle of capillary action generally described by Laplace's equation (5): p = 2G (cosA) / R. Passages, holes (apertu) in structures that allow the transport of liquids
re), used to represent pores or gaps.

 Where p is the capillary pressure, R is the capillary inner diameter (capillary radius); and G and A are as defined above.

As described in Emery I. Valko's "Penetration of Fabrics", Chapter III 83- of "Chem.Aftertreat.Text."
As revealed on page 113 (these are incorporated herein by reference), at A = 90 °,
CosA is zero and there is no capillary pressure. For A> 90 ゜
CosA is negative and capillary pressure resists liquid from entering the capillary. Therefore, in the case of a hydrophilic aqueous solution, the properties of the capillary wall must be hydrophilic in order for considerable capillary action to occur. Also, the capillary pressure decreases as R increases (larger pore / capillary structure), so R must be small enough for p to take a significant value.

Perhaps at least as important as the presence of the interfacial energy gradient is the orientation or location of the gradient itself relative to the orientation and location of the capillary or liquid passage itself.

The use of all water as a reference liquid is illustrative for discussion and is not intended to be limiting. Because the physical properties of water are very well established, water is readily available and generally exhibits uniform properties regardless of where it is obtained. The concept of the work of adhesion about water is
By taking into account the surface tension properties of the desired liquid,
It can be easily applied to other liquids such as blood, menstruation and urine.

By providing a surface energy gradient between the core and the backsheet, it provides a relatively small surface energy adjacent to the portion of the backsheet that is positioned adjacent and in contact with the absorbent core, and provides the wearer with skin. Prevents droplets from migrating from a relatively high surface energy core to a backsheet with a relatively low surface energy by providing a relatively lower surface energy portion located on the abutting side Can be. The difference in contact angle between the lower surface energy portion and the higher surface energy portion causes the droplet to move, resulting in an imbalance in surface tension acting on the solid-liquid interface. The resulting surface energy gradient, which creates a negative capillary pressure, is due to the backsheet (2,2) on the absorbent product (1).
It appears to be particularly suitable for use in perforated backsheets on absorbent products such as 4).

By providing a perforated backsheet having a surface energy gradient as described above, the likelihood of liquid passage is reduced. Due to the forces in use, the collected liquid may squeeze out of the pad (e.g., by compression, squeezed out of the absorbent core to the lower surface of the backsheet) so that the collected liquid can Such undesired movement will be hampered by the surface of the backsheet, which has a relatively low surface energy that can repel the liquid that is going to escape.

In this way, the liquid is more easily retained in the absorbent core by the driving force of the surface energy gradient between the backsheet and the core. Suitable surface treatments are available from Dow Corni, Midland, Michigan.
ng), a silicone release coating available as Syl-Off 7677, which provides 10 crosslinkers per 100 weights, available as Syl-Off 7048. Another suitable surface treatment is UV9300 and UV9380C-D1 from General Electric Company Silicone Products Division of Waterford, New York, respectively.
Is a UV-curable silicone coating consisting of two silicones, each marketed under the name, 2.5 per 100 weight. Depending on the nature of the liquid backsheet and the nature of the liquid, other coating levels may be appropriate, but when using such a silicone mixture in a forming film as illustrated in FIG. At least 0 per surface area.
A coating application level of 25 g, preferably 0.5-0.8 g, is sufficient.

Other suitable processing materials include, but are not limited to, fluoropolymers (eg, polytetrafluoro (PTFE), sold under the trademark TEFLON) and chlorofluoropolymers. From the point of view of biocompatibility,
While silicone is currently preferred for use in absorbent products, other materials that may be suitable for reducing material surface energy include petrolatum, latex,
Includes hydrocarbons such as paraffin. As used herein, the term “biocompatible” refers to glycoprotein (glucose).
-Protein), bio-specie such as platelets
s) or used to indicate a material that has low adsorption or, in other words, low affinity for biological material. Under the conditions at the time of use, these materials, compared to other materials,
As such it retains more deposited biological material.
This property makes it possible to maintain the required surface energy properties for the subsequent liquid handling conditions. Without biocompatibility, the deposition of such biological material
Surface roughness or non-uniformity tends to increase, increasing the drag force or resistance to liquid movement. Therefore, biocompatibility reduces the resistance or resistance to movement of liquids, thereby making the surface energy gradient and capillary structure faster. Maintaining substantially the same surface energy maintains the original surface energy difference for subsequent liquid deposition or permanent liquid deposition.

For the surface energy gradient of the present invention, the upper and lower limits of all such gradients are relative to each other;
That is, the interface between the backsheet and the core region that determines the surface energy gradient need not span both sides of the hydrophobic / hydrophilic spectrum. That is, a gradient may be formed by two surfaces having various degrees of hydrophobicity or hydrophilicity, and need not necessarily be performed on a hydrophobic surface and a hydrophilic surface. However, despite such a statement, to maximize the driving force applied to the water entering from the core, and to minimize the total liquid permeation to the backsheet on the clothing contacting surface Here, it is preferred that the top surface of the backsheet has a relatively low surface energy, ie is generally hydrophobic.

Thus, in the present invention, the surface energy gradient, combined with the property of unidirectional liquid transport of the backsheet, exhibits a synergistic effect, preventing liquid from being transported through the backsheet. The liquid on the first surface of the backsheet encounters two different complementary driving forces, which prevent it from moving away from the core toward the backsheet and further towards the undergarment. Similarly, these two forces also impede the movement of the liquid in the direction of the backsheet, so that the amount of liquid passing through is dramatically reduced.

In designing the perforated backsheet and core of the absorbent product of the present invention, a number of physical parameters are considered, more specifically, the magnitude and location of the appropriate surface energy gradient to properly handle the liquid. There must be.
Such factors include the magnitude of the difference in surface energy (depending on the material used), the degree of material migration (migratabilit
y), material biocompatibility, porosity or capillary size,
This includes the overall thickness and shape, the viscosity and surface tension of the liquid, and the presence or absence of other structures on either side of the interface.

Preferably, the difference in liquid contact angle between two adjacent surfaces providing a surface energy gradient is greater than 10 °, preferably
Must be at least 20 ° and the lower surface energy surface must have a liquid contact angle of at least 90 °, preferably at least 100 °, more preferably at least 110 °, most preferably at least 120 ° .

According to the present invention, by making the surface more hydrophilic, the contact angle of the layer can be increased. To manufacture the backsheet shown in FIG. 2 of the present invention, a sheet of polyethylene is extruded onto a drum where it is formed into a perforated film that has been vacuum formed and, if desired, Thom.
As et al., U.S. Patent No. 4,351,784 (September 28, 1982), Toh
U.S. Patent No. 4,456,670 to Mas et al. (June 26, 1984) and U.S. Patent No. 4,535,020 to Thomas et al.
Subject to a corona discharge treatment generally similar to the teachings of U.S. Pat. Subsequently, a surface treatment having a relatively smaller surface energy is applied to the wearer-side surface of the perforated formed film, and is preferably cured.

However, biocompatibility and low surface energy are not synonymous. Materials such as polyurethane exhibit some biocompatibility but relatively high surface energy. At present, suitable materials such as silicones and fluorinated materials exhibit usefully low surface energy and biocompatibility.

Another suitable method for converting a ribbon of polyethylene film into a formed perforated film is to apply water to one surface of the film, preferably from water or the like, while applying a vacuum to the opposite surface of the adjacent film. To provide a high pressure liquid jet. Such a method is described in U.S. Pat. No. 4,609,518 to Curro et al.
Curro et al., U.S. Pat. No. 4,629,643 (Dec. 16, 1986).
US Patent No. 4,637,819 to Ouellette et al.
20); Linman et al., U.S. Patent No. 4,681,793 (July 1987).
21); Curro et al., U.S. Patent No. 4,695,422 (September 1987).
22) Curro et al., U.S. Patent No. 4,778,644 (Oct. 1988).
Curro et al., U.S. Patent No. 4,839,216 (June 1989).
March 13); Lyons et al., U.S. Patent No. 4,846,821 (July 1989).
And the disclosures of each of said patents are incorporated herein by reference. The perforated film may be subjected to a corona discharge treatment, if desired. Next, a silicone release coating may be applied or printed on the first surface of the perforated film, and is preferably cured. The surface energy of the siliconized surface is lower than the surface energy of the untreated surface of the backsheet.

Alternatively, a layer exhibiting lower surface energy (eg, a perforated polymeric backsheet layer) may incorporate a low surface energy material into the layer such that the layer becomes hydrophobic during manufacture. Thereafter, a low surface energy material may be applied to the surface of the layer. Typically, the layer makes up 5% of the total weight of said layer of low surface energy material.

According to the present invention, the absorbent product is constructed by joining various elements such as a topsheet, a backsheet and an absorbent core by any means known in the art. For example, the backsheet and / or topsheet may be attached to the absorbent core, or by a uniform continuous layer of adhesive, a layer of patterned adhesive, or separate continuous lines, spirals, or punctiform adhesives. May be joined. Alternatively, the element may comprise a heat bond, a pressure bond, an ultrasonic bond, a mechanical mechanical bond or any other suitable bonding means known in the art, and optionally You may join by combining things.

According to the present invention, the absorbent product comprises a sanitary napkin,
It may be used in panty liners, adult incontinence products and baby diapers. Thus, depending on the intended use of the product, along with the ingredients described herein, the absorbent product may have resilient fixtures, fasteners, etc.
ing device). In particular, it is believed that the present invention can be used for sanitary napkins and panty liners.

Examples: The absorbent products of the present invention were prepared as shown below.

The backsheet has the following raw materials: a) 14 g / m ² spunbond layer and 14 g / m ² meltblown, MD2005 name Peine, Germany
28g non-woven cloth available from Corovin GmbH
/ m ² b) American Treadgar film
U.S. Pat. No. 3,929,135 polyethylene forming film available from Products, which has a 19% void area, an embossing thickness (funnel height) of 0.48 mm, and circular holes with a garment side surface pore size of 0.465 mm. Made from

The backsheet comprises the above-mentioned film layer (b) in which projecting holes are oriented on the wearer-side surface of the absorbent product having the non-woven cloth (a) in which the spun blow is the clothing-side surface of the absorbent product.
Was prepared by bonding.

Each test sample was prepared under identical conditions in all respects, except for the special treatment given to the material forming part of the backsheet structure or the material in direct liquid contact with the backsheet. The test samples were prepared according to normal manufacturing procedures, except that the backsheet attachment was very low relative to the entire structure.
A sanitary pad manufactured from Procter & Gamble GmbH, Schwalbach / Germany and manufactured under the trade name "Always Ultra Normal" was manufactured. This made it possible to remove the existing backsheet consisting of an impermeable plastic film (for both liquid and gas) and replace it with another breathable backsheet. The structure of the sanitary napkin is surface treated (by silicone coating,
Lowers the surface energy of one liquid / solid surface)
The results were the same in all examples except that was added.

Example 1: (reference) A breathable backsheet as described herein above is a unidirectional, conical perforated made of low density PE manufactured by Treadgar, USA under production code X-1522. It is composed of a film (CPT; conical aperatured film), and is placed in contact with an absorbent core made of a tissue and an absorbent gel material. The contacting wearer's surface is MD
Consists of a non-woven laminate manufactured by Corovin GmbH, Germany under the trade name 2005. Non-woven laminate, the span of 14 g / m ² bond and 14
Consists of g / m ² meltblown. No further surface treatment was given.

Example 2: Example 2 is Walkisoft, Denmark
Core surface (substance code: Metmar Kotka) (present in contact with the wearer surface (31) of the unidirectional perforated film) supplied by ) Is identical to the structure of Example 1, except that it was treated with about 6 g / m ² of thermoset silicone. The silicone is manufactured by Dow Corning, USA and has SYL-OFF 7048 Crosslinker / SYL-OFF 7677, release coat.
er) (mixing ratio 10%: 90%).

Example 3: Example 3 is the wearer surface (31) of a unidirectional perforated film (CPT) made of low density PE manufactured by Treadgar, USA, under production code X-1522.
(Present in contact with the absorbent core tissue 200)
The structure is the same as in Example 1, except that it has been further treated with a weighed approximately 3 g / m ² heat cured silicone. The silicone is manufactured by Dow Corning of the United States,
It was sold under the trade name SYL-OFF 7048 Crosslinker / SYL-OFF 7677, release coater (mixing ratio 10%: 90%).

Example 4: Example 4 shows that the unidirectional perforated film is a low density PE (84
%) And silicone (16%) are mixed,
Treadgar Film Products B. of the Netherlands on order of P & G Pescara Technology Center SpA
The same structure as in Example 1 except provided by V. The material was made under the same conditions as the material manufactured as Code X-1522.

Example 5: Example 5 is an example except that the unidirectional perforated film (CPT) is made of high density polyethylene (supplied by Treadgar Film Products of the United States; development code 15112). 3 is the same structure. As in Example 3, the wearer-side surface 31 of the unidirectional perforated film (CPT-HDPE), which is in contact with the tissue of the absorbent core, is further weighed about 3 g / m ² of heat. Treated with cured silicone. The silicone was manufactured by Dow Corning America (SYL-OFF 7048 Crosslinker / SYL-OFF 7677, trade name, 10%: 90% ratio).

Test Methods Test Nos. 1a and 1b-Liquid Pass Test The liquid-through test is used to evaluate the resistance of a breathable backsheet or backsheet structure to the transfer of extracorporeal discharge. As detailed in the method below, the test was performed by simply changing the composition of the test solution to make the porous backsheet as impermeable as possible to maximum extracorporeal discharge. It can be used as a direct indicator of whether there is.

Basic principle of the method The basic principle of the test is to simulate the loading of extracorporeal emissions on disposable absorbent products during use. To achieve this, a product, such as a sanitary napkin, is prepared and placed in a transparent test stand made of Perspex.
It was placed horizontally. The product is positioned so that the wearer side surface is visible (up) and the backsheet / garment side is in contact with the test stand (down). Suspended above the sample for analysis is a liquid supply system that can supply any desired amount of the desired test liquid (one at a time or stepwise as desired). Between the outermost surface of the test sample and the transparent test stand is a sheet of absorbent filter paper. The absorbent filter paper simulates a sanitary napkin adhered to, for example, panties, or a diaper / incontinence device in close contact with clothing, in close contact with the backsheet of the test sample. Immediately below the transparent test stand is a mirror positioned to allow continuous observation of any changes in the absorbent filter paper (wet with a colored solution simulating extracorporeal discharge). For example, if the porous backsheet is unable to sufficiently hinder the transfer of liquid, the filter paper can be wetted with the colored solution and observed with a mirror. The amount of liquid transferred can be easily recorded, along with the time dependence of the transfer, either as the weight, or more preferably the size, of the stain on absorbent filter paper (simulating panties).

The test solution is applied to the test sample via a graduated delivery system, such as a conventional burette, according to the desired test approach as described below. Once the test solution is placed on the pad, it is left for one minute to allow the solution to be absorbed into the test sample, so that the test solution does not accumulate on the topsheet (wearer's surface).

After waiting for one minute, 70 g /
Place the test sample under a pressure of cm ² . The test sample is left under a pressure of 70 g / cm ² for 30 minutes. For example, the area of colored stains on absorbent paper is measured at 5 minute intervals. The process of mobility or diffusion of extracorporeal excretions, such as blood, may be relatively time consuming, so it is imperative to measure it over time.

It is also important to understand the mechanism of the liquid passage problem and make sure that the correct test design can correctly assess it. For example, relatively large holes (> 200μ)
m), the breathable backsheet having a relatively fast extrusion process when the test sample is placed under pressure (the pressure applied when sitting may push liquid out of relatively large holes). No), it is easy to cause trouble. On the other hand, as the pores become smaller (<200 μm), the simple diffusion process or the diffusion process caused by the capillary becomes more likely.
Such a process is slower than the extrusion process.

Method 1a: High gush simulatio
n) This first test design measures the impermeability of the porous backsheet under a high load (test solution bursts at a large pressure) simulation. The absorbent core (or structure) works to fully absorb extracorporeal waste,
Controlling this in-use condition is the most difficult, as it typically takes some time to bond (often happens when you stand up after a long sleep or sitting) ). For example, absorbent cores and absorbent gellings made of cellulosic fibers (airfelt, tissue) take several minutes to fully absorb liquids and to be able to bind tightly. Unbound emissions occupying the interstices or spaces between the fibers are extremely mobile and can immediately move towards the porous backsheet, be pushed out by pressure, or be transported through the backsheet via capillary forces. .

In accordance with the description in the above outline, for a typical sanitary napkin, a high ejection simulation test is performed under the following conditions.

Test solution: synthetic urine + 1% surfactant, or artificial menstrual fluid + 1% surfactant Ejection volume (ml): 10 ml for sanitary napkin Ejection speed (ml / min): 10 (ie, 10 ml in 60 seconds) Pressure applied: 70 g / cm ² (wait 1 minute) The result is in cm ² after 5, 10, 20 and 30 minutes
Expressed as the area of the stain / the amount of liquid passing through.

Method 1b: Repetitive Load Simulation In the first study design, ventilating at more typical loading conditions where extracorporeal discharges occur regularly and occur as repetitive steps rather than a single squirt. Measure the non-permeability of the backsheet. A repetitive load simulation, such as that performed on a typical sanitary napkin, is detailed in the above overview and is specifically subject to the following conditions. Specifically, 5 ml of the test solution (see below) is loaded onto the test sample and placed in the center of the test sample. After one minute, the test liquid is absorbed,
The sample is placed under pressure for 5 minutes. After this period, the size (area) of the liquid passage is measured and recorded. The pressure is immediately removed and the sample is again given a second 5 ml load of the test solution. Again, the liquid is sampled (at this stage, 10ml
1 minute, and then put under pressure for 5 minutes. After this period, the size (area) of the liquid passage is measured and recorded. The pressure is immediately removed and the sample is again given a third 5 ml load of the test solution. Again, wait 1 minute for the liquid to be absorbed into the sample (currently containing 15 ml of test solution), then place under pressure for 5 minutes and measure the size of the stain (liquid passage) again. Continue the cycle until the pad is loaded with 20 ml.

Test solution: synthetic urine + 1% surfactant or body fluid during menstruation + 1% surfactant Ejection volume (ml): For sanitary napkins,
5 ml load Max load: 20 ml Load speed (ml / min): 2.5 (ie 5 ml in 2 minutes) Pressure applied (after waiting 1 minute): 70 g / cm ² Results are 5, 10, 15 and 20 ml loads Sometimes expressed in cm ² as the area of the stain / the amount of liquid passed.

The type and amount of test solution used in the test method In order to reliably evaluate the design of a promising breathable backsheet, the conditions of the test solution must be tailored to the end use of the product. Sanitary napkins are designed to hold menstrual discharge. Such emissions vary widely from woman to woman and may contain varying levels of detergent impurities from fatty acids and daily hygiene practices (washing, washing, etc.). These components are very mobile and may have very low surface tension. It has been found that the kinetics of actual menstrual discharge is simulated using artificial menstrual fluid from sheep blood and mucine, supplemented with surfactants as detailed below. . The squirt volume of the 15 ml test solution is quite high, and 99% of the squirt state in use will fall within this range. Similarly, the sanitary napkin at the time of use contains 20 ml (of all sanitary napkins).
(95% fall within this range), but rarely more. Typically,
The sanitary pad is loaded with 10 ml (90% of total pad) or less.

Incontinence pads, baby diapers, or panty liners (pads worn by women during menstruation or at the beginning / end of menstruation) must meet different requirements than sanitary napkins, but also on sanitary napkins. A test solution close to urine output can be applied. However, body impurities (fatty acids, surfactants and residual detergent)
Was also found, and it was confirmed that when a surfactant was added to the synthetic urine solution, it was very similar to the state during use. Feminine hygiene products (sanitary napkins, panty liners) are usually used as minor incontinence tools,
It is also appropriate to evaluate the potential breathable backsheet material or structure using a synthetic urine solution containing a surfactant. Again, the volumes were chosen to reflect the typical conditions in which the product would be exposed by such use. When applied to diapers, or more stressful incontinence, the method can be easily modified to simulate higher test solution loads and transport rates.

Preparation of Test Solution Synthetic Urine + 1% Surfactant (UreaB / 1%) First, in a 10 kg parent batch, prepare test solution synthetic urine, take a small amount of the required amount, and add the surfactant. each
A 10 kg UreaB batch is composed of the following ingredients:

Component formula weight / 10 kg Batch urea 200g sodium chloride NaCl 90 g magnesium sulfate MgSO ₄ · 7H ₂ O 11g calcium CaCl ₂ 6 g Distilled water H ₂ O 9693g all chloride reagents are of "reagent grade", the general chemical sales Can be obtained from people. In addition, for the surfactant, Peosperse 200ML is purchased from Pegesis, USA. For each measurement, typically 100 ml of test solution (UreaB / 1) is mixed by mixing 90 ml of UreaB solution and 10 ml of surfactant.
% Surfactant). The UreaB / 1% surfactant must be constantly mixed so that the components do not separate before use.

Preparation of test solution: artificial menstrual fluid + 1% surfactant Artificial Menstrual Fluid (AMF)
Based on conditioned sheep blood, viscosity, electrical conductivity,
The surface tension and appearance have been modified to be very close to human menstrual fluid. Furthermore, surfactants introduced from typical hygiene practices (and, in limited circumstances, food effects) or stress conditions such as unexpected levels of fatty acids (which may lower blood surface tension) are more likely to occur. To reflect well, we include a surfactant (1%) in the test solution (supplied by Pegesys / USA). Menstruation with low surface tension is the biggest cause of trouble with liquid permeation through the backsheet into breathable absorbent products such as sanitary products.

Reagents (1) Defibrinated sheep blood was obtained from Unipass S.
pA ｛Garbagnate Milanese / Italy｝ (2) Lactic acid of reagent grade (85-95% w / w) from JT Baker (Netherlands) (3) Sigma Chemical Co., USA
Potassium hydroxide (KOH) from Co.), reagent grade (4) Phosphate buffered saline tablets from Sigma Chemical Co., USA, reagent grade (5) Chlorination from Sigma Chemical Co., USA Sodium, reagent grade (6) Stomach mucin from Sigma Chemical Co., USA, Type III (CAS 84082-64-4) (7) Distilled water Step 1 Dissolve lactic acid powder and distilled water, 9 ± 1% A lactic acid solution of is prepared.

Step 2 Dissolve the KOH powder in distilled water to prepare a 10% potassium hydroxide (KOH) solution.

Step 3 Prepare the phosphate buffer buffered to pH 7.2 by dissolving the tablets directly in 1 L of distilled water.

Step 4 Prepare the following composition: 460 ± 5 ml of phosphate buffer solution 7.5 ± 0.5 ml of KOH solution and heat slowly to 45 ± 5 ° C.

Step 5 Prepare a mucous solution by slowly dissolving (always stirring) about 30 g of gastric mucin in the preheated (45 ± 5 ° C.) solution prepared in Step 4. Once dissolved, the solution temperature must be raised to between 50-80 ° C. and the mixture must be covered for about 15 minutes. Temperature is 40-50 ℃
, While keeping the temperature relatively constant, the heat is cooled, and stirring is continued for 2.5 hours.

Step 6 Remove the solution from the hot plate and allow the solution (from step 5) to cool below 40 ° C. Add 2.0 ml of 10% lactic acid solution and mix well for 2 minutes.

Step 7 Place the solution in the autoclave and heat to a temperature of 121 ° C. for 15 minutes.

Step 8 Allow the solution to cool to room temperature and dilute 1: 1 with defibrinated sheep blood.

After the preparation of AMF, its viscosity, pH and conductivity are measured to confirm that the properties of the blood are in a range similar to normal menstrual blood (HzBussing's "zur Biochemiede Men").
strualblutes ", Zbl Gynaec, 179,456 (1957)).
The viscosity must be in the range 7-8 (unit cStK).
pH is in the range of 6.9 to 7.5 and conductivity is 10.5 to 13 (mm
ho). If the viscosity is not within the above range, it must not be used and a new batch of AMF must be prepared. This may require adjusting the amount of mucin in the stomach used. Since this is a natural product, its composition may vary from lot to lot.

For each measurement, 100 ml of the AMF test solution containing the surfactant is prepared, typically by mixing 10 ml of the surfactant with 90 ml of the AMF solution (maintained at 25 ° C.). The AMF / 1% surfactant solution must always be mixed so that the components do not separate before use. The solution must be used within 4 hours after preparation.

Method No. 2: Determination of liquid contact angle The contact angle test is a standard test for evaluating the nature of the interaction between a solid surface and a droplet. The contact angle that a droplet forms on a surface is a reflection of some interactions.
In addition to the nature of the liquid-solid interaction, there is the nature of the liquid, its surface tension, the nature of the solid, the surface abberation. In general, droplets on rough surfaces typically exhibit a higher contact angle than droplets on smooth surfaces of the same chemical composition. If the water droplet shows a contact angle greater than 90 °, the surface is considered to be “hydrophobic” to the liquid. If the contact angle is less than 90 °, the surface is considered “hydrophilic”.

Basic principle of the method The contact angle formed by a liquid on a surface can be measured by various techniques, including optical analysis of droplets on the surface, as well as more reliable techniques. The technique used to measure the contact angle is the "Wilhelmy Plate Technique". The principle of this technique is to suspend a solid sample on a container of water, gradually sink the sample into liquid water to a certain depth, and then move it. The effect of water,
The retarding force on the contacting material sample (with zero sink depth) is measured by microbalance and determines the cosine of the contact angle from the formula:

Where F = force of the sample at zero sinking depth, determined by balance (mg) p = boundary line of the sample at the interface (cm) ST = surface tension (dyne · cm) Cosφ = cosine of contact angle g = gravitational acceleration (measured) The instrument used to measure the contact angle was Cahn Instruments Inc. Cerritos CA 9
0701-2275 USA) Automated “Dynamic Contact Angle Analyzer (model
DCA-322) "). Prepare one sample (24 mm x 30 mm) for each measured material (see table) and attach it to a glass slide as specified in the equipment manual. Care must be taken not to touch the surface, otherwise the surface of the material may be contaminated: each material must be measured five times to ensure the accuracy of the measurement and And minimize the effects of surface variations or surface non-uniformity.

The contact angle of the liquid on the surface, and the ability of the porous material to transport the liquid by either a capillary or drainage process, depends on the surface abrasion or surface structure, the nature of the liquid, and the interaction of the liquid with the surface And the transport mechanism. The test solution used in this test was
Distilled water with high hydrophilicity and high surface tension. This increases the contact angle compared to the contact angles typically found or expected to be found in effluents such as body fluids or urine during menses. Therefore, the results of the absolute contact shown in the table need to be watched carefully. Even if the contact angle exceeds 90 degrees with water,
It does not mean that the holes in the material are exerting a negative capillary force on the discharge, such as menses. However, increasing the contact angle will tend to reduce the transport / efficiency of liquid (either based on capillary or drainage) through the material.

na = not applicable, the material already shows a large contact angle.

Method No. 3: Unidirectional liquid transfer test The unidirectional liquid transfer test is used to quantify the directionality of the liquid transfer characteristics of each surface of the perforated film with respect to body discharge. This test measures how permeable each surface is to a wide range of bodily discharges by simply changing the composition of the test solution, as detailed in the method description below. Can be used as a direct indicator.

Basic principle of the method The basic principle of the test is to evaluate the performance of unidirectional / unidirectional perforated films on liquids simulating bodily discharges. A "perforated film" is a film that has a clear selectivity of transporting liquid from one surface to another, but not in the opposite direction, the film must be reversed and the test continued. Must. Therefore,
A "good perforated film" is a film that not only has a clear directionality for liquid transport but also minimal transport of liquid in a direction that can be used in a breathable backsheet structure.

To evaluate the directional liquid transport rate of a perforated film, a simple test is performed in which a liquid-saturated absorbent structure is placed on a perforated film that is overlaid with absorbent blotting paper. Pressure is applied on the whole mass (saturated absorbent material, film and blotting paper) and the amount of test solution transported through the perforated film to the blotting paper and absorbed by the blotting paper is measured. In a second experiment, the direction of the film is reversed and the experiment is repeated. Surface 1 and Surface 2
Record and evaluate the magnitude of liquid transport through the system.

Specifically, a commercially available filter / blotting paper (Cartiera Favin) having a size of 12 cm × 12 cm is used.
i Manufacturing of SpAItaly; Type Abssorbente Bianca “N30”
(Retail store Ditta Bragiola SpA. Perugia, Italy)) Weigh 10 stacks and place them horizontally on a test stand directly below the suspended weight. A stack of blotting papers (each surface is optionally labeled 1 and 2) and a perforated film sample measuring 8.5 cm x 8.5 cm is evaluated. On top of the perforated film is placed a layer of fully saturated absorbent material. The absorbent material can be purchased from Warkisoft, Denmark, under the code of the manufacturer of Met Mar Cocker, (each sheet)
Includes a commercial air layer with a weigh of 63 gsm (airlayed)
It consists of two sheets of absorbent tissue and is used to simulate a liquid-saturated absorbent core. Each sheet of the tissue has a size of 5 cm x 5 cm,
They are placed symmetrically on top of each other. The tissue structure is then completely submerged for one minute in synthetic urine (see the solution detailed in Method 1) to ensure complete saturation.

Remove the tissue from the liquid and hold it vertically for 60 seconds to remove excess liquid before placing it directly on the perforated film. The saturated tissue is placed in the center of a perforated film placed in the center of the stacked blotting papers.

In the final stage of the test, a block of perspex (8.5 cm × 8.5 cm) was placed in the center on the saturated tissue structure and the weight was automatically lowered onto the sample, 130 g / cm ^2. Pressure for 60 seconds. In order to ensure the reproducibility of each test, the weight is lowered and the time is adjusted using simple electric equipment.

The pressure applied on the entire assembly (saturated material, film, and blotting paper) causes the liquid in the saturated tissue to drain onto the film, and the movement of the liquid through the perforated film in a favorable direction. Liquid must travel through the film and be absorbed by the blotting paper. Remove the weight, separate the layers, check if the blotting paper is wet with liquid and weigh. The difference in weight (before and after) is recorded and compared to a second experiment in which the direction of the perforated film is reversed, and the mobility of the test liquid in the opposite direction through the perforated film is measured.

Test solution: Preparation of test solution Urea B / 0% Test solution Synthetic Urine Urea B / 0% is prepared in the same manner as test solution Urea B / 0%, except that no surfactant is added to the test solution. Prepared by

Method No. 4: Measurement of gap areaA disposable product designed to hold bodily excrement and having a breathable back sheet is designed to be able to exchange air and water vapor with the outside. I have. The extent or efficiency of the process (from the point of view of the user's benefit) depends on the gap area of the breathable backsheet backing of the disposable product, especially the area in contact with the body or susceptible to blockage by body parts. Can be related to In this test, in addition to the local level, only the gaps in the breathable backsheet are measured for an average level that reflects the entire product.

Basic Principles of the Method The void area can be determined for both materials that assemble or combine to form a breathable backsheet structure, or for an absorbent product containing a breathable backsheet or structure.

Material: The calculation of the gaps in the material is relatively straightforward. Material samples can be best viewed with a microscope, and a magnified or static photograph of the microscope must be recorded. The image is then placed on a grid of mm grid so that the number of holes per cm ² and the area of each hole can be easily calculated. Alternatively, the image may be scanned as digital information to determine the number of holes per cm ² and the area of the holes. The gap is (total area of each hole) /
(Total area analyzed).

Absorbent products: The voids of an absorbent product containing a breathable backsheet are determined primarily by calculating the "primary voids" in the area that is believed to be responsible for efficient communication with the environment. Breathable areas, which are considered less important, are evaluated only as an "average void fraction" value as part of the overall product. For example, if areas that are not in intimate contact in an absorbent product, or areas in an absorbent product that are less likely to be involved in skin occlusion, are provided with breathability, they may be assigned a `` major gap '' value. Shall not be calculated as part of

Step 1: When the product is viewed under a microscope, there should be areas with different levels of porosity and different
Give a grade. It should typically be expected that regions of different permeability should be present and only those regions which show little or no permeability will usually be found. However, if this is not the case, it may be marked for further evaluation.

Step 2: For each region, a magnified image or a still picture must be taken. The image is then placed on a grid of mm grid so that the area of each hole can be easily calculated and the number of holes per cm ² can be easily determined. Alternatively, the image may be scanned as digital information to determine the number of holes per cm ² and the area of the holes. The gap is simply defined as (total area of each hole) / (total area analyzed).

The analysis is continued for each region with different porosity or air permeability.

 Next, the "average gap area" of the entire product is calculated.

Step 3: The "primary gap" is simply the gap in the area calculated in step 2 that is present in the area of the pad and is believed to contribute most to the usefulness of the breathable absorbent product during use Things. The assessment of major or minor areas is subjective, but can be done in one of two ways.

Approach 1: Have a representative group of users (for example, women in the case of a sanitary napkin or light incontinence product) wear the product, determine which parts of the product are in close proximity to the body, and if an obstruction occurs. Evaluate what is gained. These were rated as major areas, in all of these areas the backing had to be porous, and subsequently they were classified as "major gap" areas.

Approach 2: The product is analyzed by data bank analysis to compare specific product characteristics that affect pad fitness to the body (measurement of flexibility, product size, thickness, etc.) with known wear characteristics. Recognized, purely technical. By such a pure technical analysis, a major area or a minor area can be identified.

The illustrated perforated films and alternative materials currently available from many companies were tested and the results are detailed in Table 4.

The film is a three-dimensional film having conical holes such that the size of the holes varies greatly on each surface. Surface 1 is defined as the surface facing the wearer when used as a breathable backsheet material.

Continuation of the front page (73) Patent holder 592043805 ONE PROCTER & GANB LE PLAZA, CINCINNATI, OHIO, UNITED STATS OF AMERICA (72) Inventor Divo, Michael Deutschland, Germany-61381 Friedrichsdorf, Feldberg 14 (72) Inventor Veglio, Paolo Italy, Ai-65100 Pescara, Via Piomba 23 (56) References JP-A-49-1111739 (JP, A) JP-A-50-49041 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) A61F 13/15-13/84

Claims (11)

(57) [Claims] 1. A disposable absorbent product comprising a liquid-permeable topsheet, an absorbent core, and a backsheet, wherein the core is located between the topsheet and the backsheet, and the backsheet comprises: A liquid-permeable polymeric film layer that allows liquid to move unidirectionally in the direction of the core; and an outer layer, wherein the core includes a liquid storage layer, and each of the layers has a wearer-side surface and a garment-side surface. Wherein said each surface of said layer has a liquid contact angle, wherein said absorbent product is located below said topsheet;
A lower portion consisting of a portion located between the garment-side surface of the liquid storage layer and the garment-side surface of the outer layer, a wearer-side surface between adjacent layers in the lower portion,
A disposable absorbent product having a liquid contact angle greater than the liquid contact angle of the adjacent garment side surface of the adjacent layer. 2. A disposable absorbent product comprising a liquid-permeable topsheet, an absorbent core, and a backsheet, wherein the core is located between the topsheet and the backsheet, wherein the backsheet comprises: A liquid-permeable polymeric film layer for transferring liquid in one direction toward the core; and an outer layer, wherein the core includes a liquid storage layer, and the backsheet includes an outer layer. Has a wearer side surface and a garment side surface, wherein each said surface of the layer has a liquid contact angle, wherein the absorbent product is located below the topsheet;
A lower portion comprising a portion located between the garment-side surface of the liquid storage layer and the garment-side surface of the outer layer, wherein the garment-side surface of at least one of the layers in the lower portion is the same layer; A disposable absorbent product having a liquid contact angle greater than the liquid contact angle of the wearer's surface. 3. A disposable absorbent product according to claim 1 or 2, wherein at least one of the layers below the storage layer comprises a low surface energy material. 4. The disposable absorbent product according to claim 3, wherein said low surface energy material is selected from curable silicones, fluoropolymers, hydrocarbons or mixtures thereof. 5. The disposable absorbent product according to claim 3, wherein at least one of said layers under said storage layer.
A disposable absorbent product comprising at least 5% of a low surface energy material by total weight of the layer. 6. A disposable absorbent product according to claim 1 or 2, wherein any of the garment-side surface or the wearer-side surface of any of the layers in the lower portion is at least 0.25 per square meter of the surface. Disposable absorbent products with low surface energy material of g. 7. The disposable absorbent product according to claim 1, wherein the core comprises at least two parts, a first part comprises the storage layer, and a second part comprises fibers. A disposable absorbent product comprising a layer, wherein the fiber layer is adjacent to the backsheet. 8. The disposable absorbent product according to claim 1 or 2, wherein the wearer side surface of any of the layers is at least 10 ° greater than the liquid contact angle of the adjacent surface. Disposable absorbent products with large liquid contact angles. 9. The disposable absorbent product according to claim 2, wherein the liquid contact angle of the garment-side surface of the storage layer is at least 90 °. 10. The disposable absorbent product according to claim 1 or 2, wherein the absorbent product comprises:
Disposable absorbent products with a continuous liquid contact angle gradient. 11. The disposable absorbent product according to claim 1, wherein the product is a sanitary napkin or a panty liner.