Patent Application
20070197994
This invention relates to disposable absorbent articles comprising a topsheet (20) that comprises one or more elastic laminate portion(s) (10) with substantially y-direction elongation (stretch), formed from a topsheet material (supporting material), and an elastic material (12) (and optionally an attachment means and/or attachment sheet and/or cover strip (13)), whereby said elastic laminate portions (10) have wrinkles of a very low wrinkle height and a selected average wrinkle density, in order to reduce the risk of severe pressure marks. The elastic laminate portion(s) (10) are preferably very thin. The provision of such elastic laminate portions (10) still provides an excellent force profile for the topsheet (20) and the absorbent article as a whole. Overall, comfortable-to-wear absorbent articles are obtained that provide excellent exudates isolation away from the skin whilst causing very little or no pressure marks in use.
Absorbent articles such as infant diapers, training pants and adult incontinence garments typically comprise elastic leg cuffs and or barrier cuffs to reduce leakage of exudates from the article. Often, they also comprise an elasticated waist band, to improve the fit and comfort when the wearer is moving. A certain type of diapers for feces isolation comprises (also) a topsheet with a large opening with there along elastic bands to ensure correct alignment of the topsheet and the opening with the anus of the user, and to thus ensure optimum reception and isolation of the feces under the topsheet.
These elasticated portions of such articles typically comprise an elastic material laminated to a non-elastic sheet, such as a plastic film, or nonwoven material, obtained by attaching the elastic material in stretched state to the sheet. The resulting laminate thus comprises in unstretched, contracted state and in partially stretched state a surplus of sheet material that forms wrinkles.
Such elasticated portions of the diaper can be uncomfortable in use, due to the pressure of the elastic portions on the skin and/or due to rubbing of the wrinkled elasticated portions over the skin.
The inventors have also found that even if the user does not experience the elasticated portions as uncomfortable, the red skin marks caused by the elasticated portions may still be perceived by the care taker as uncomfortable for the user.
The inventors have found that this problem can be ameliorated by use of elastic laminate portion (s) that, at least on the surface that faces the body in use, have wrinkles of (on average) a very small z-dimensions (height), and that have a very selected wrinkle density (wrinkles per cm). They found that such elastic laminate portions leave at the most very minor, shallow pressure marks (wrinkle indentations) on the skin, that disappear very quickly and that are (perceived as) less troublesome. Furthermore, if such minor pressure marks are still formed, they are believed to create less of a risk of skin irritation. They also found that it is beneficial that the elastic laminate portions (s) are very thin, at least in the free edge area.
Thus, absorbent articles are provided that still maintain an excellent elastic profile and performance and that at the same type have a highly reduced, or no pressure mark problem and that are more comfortable in use.
The invention relates to a disposable absorbent article comprising a topsheet (20) having an opening and one or more longitudinally extending elastic laminate portions (10), formed by at least an elastic material (12) attached to the topsheet (20), said elastic laminate portion (s) (10) extending along at least part of said opening, said laminate portion (s) (10) comprising in at least relaxed and partially contracted state a body-facing surface with a multitude of wrinkles, and whereby said elastic laminate portion (10) has an absolute contracted length Lc and a fully stretched absolute length Ls,
whereby at a partial elongation of the elastic laminate portion (10) of ε=0.5:
a) said wrinkles have an average wrinkle height Hw of less than 600 micrometers; and
b) said elastic laminate portion (10) has an average wrinkle density Dw between 5 and 10 wrinkles per cm, preferably between 5 and 9 wrinkles per cm, or in certain embodiments between 5 and 7.5 or even 7 wrinkles per cm.
Said elastic laminate portion (10) has in one embodiment an average caliper (at 0.33 psi and at an elongation ε=0.5) up to 1.3 mm, typically up to 1.0 mm.
The article is preferably a diaper, e.g. an adult incontinence garment, baby or infant diaper or training pants.
Furthermore, the inventors have found that pressure marks may result in skin irritation if the pressure marks are caused by hydrophilic elastic material that may be wet in use, because the wetness can increase the skin irritation. Thus, the inventors have found that it is beneficial to ensure that such the nonwoven material, used in the laminate portions, are hydrophobic.
It may be preferred that the topsheet (20) itself is not elastically stretchable in y-direction.
The opening may be an elongated slit opening.
“Absorbent article” refers to wearable devices, which absorb and/or contain liquid, and more specifically, refers to devices, which are placed against or in proximity to the body of the wearer to absorb and contain the various exudates discharged from the body. As used herein, the term “diaper” refers to an absorbent article generally worn by infants and incontinent people about the lower torso.
“y-direction” elongation or stretch as used herein means that the topsheet (20) or laminate portion (10) has as a whole an elongation or stretch in an average direction, that is herein referred to as “y-direction’. This may be a direction within 45 degrees of the longitudinal axis or line parallel thereto of the topsheet (20) or elastic laminate portion (10).
“Absolute fully stretched length” is the length of the topsheet (20) or elastic laminate portion (10) when said topsheet (20) or portion (10) is stretched in y-direction to its maximum length, as set out herein.
“Absolute contracted length” is the length of the topsheet (20) or elastic laminate portion (10), when no stretching force is applied to it, e.g. when it is in relaxed state, flat on a surface.
The “z-direction” is perpendicular to the y-direction and substantially in the direction of the wrinkle height in the elastic laminate portion (10), and is herein also referred to as the height or thickness dimension.
The “x-direction” is perpendicular to both the x- and y-directions.
As used herein, “elastic” means, that the item is extendible or stretchable by application of a force in a certain direction and returns to at least 80% of its original length but to less than 150% of its original length in that direction, and typically to about its original size, after the stretching force is released.
As used herein, “along” means at least partially parallel and in close proximity or even in contact with.
As used herein, the opening in the topsheet (20) is an area completely circumscribed by the topsheet (20), but where the topsheet (20) material is not present, and which is large enough to receive fecal material, typically being at least 2 cm long or wide, or having a surface area of at least 2 cm2.
As used herein, the term “void space” is a cavity in the article present in at least the relaxed state, which serves to accept and contain bodily exudates such as fecal material, typically being at least 5 cm3 in relaxed state.
As used herein “attached” includes “directly attached” and “indirectly attached”, e.g. via attaching “a” to “b” by attaching “a” to “c” and “c” to “b”.
Each embodiment defined by certain properties or dimension for which a value is defined herein is to be understood to include embodiments with functional equivalent properties or dimensions, e.g. a dimension of 0.5 cm has to be understood as meaning “about 0.5 cm”.
The disposable absorbent article of the invention may be a sanitary napkin, panty-liner, or a diaper, i.e. an adult incontinence garment or infant diaper (as shown in the FIGS. 1 to 5) or training or pull-up pants. The article comprises the topsheet (20) with an elastic laminate portion (10), described herein, and additional components, to have typically at least a backsheet (21), absorbent core (23) and a core cover sheet or topsheet (20).
The absorbent article of the invention comprises at least a topsheet (20) comprising at least one elastic laminate portion (10), formed from at least an elastic material (12) and a part of the topsheet material, e.g. the supporting topsheet material (13), that itself is typically not elastically stretchable, said elastic laminate portion (10) having at least y-directional stretch (elongation), or only y-directional stretch, as shown in the Figures. The article may also comprise other components that comprise such an elastic laminate portion(s) (10) such as leg cuffs (24) or barrier cuffs (26) or a waist band (s) (25).
The longest dimension or length of the topsheet (20) and of the elastic laminate portion (s) (10) are typically parallel to the y-axis of the topsheet (20) and of the article and this is typically substantially parallel to the average direction of stretch of the elastic laminate portion (10) and topsheet (20). If for example the leg cuffs (25) or barrier cuffs (26) comprise or consist of said elastic laminate portion (10) as well, then the y-direction of the leg cuffs (25) or barrier cuffs (26) and said laminate portion(s) (10) are typically substantially parallel or on average parallel to the y-direction and y-axis of the article.
Said topsheet (20) may comprise more than one of such laminate portions (10), which each may or may not be identical. For example, the topsheet may comprise at least two separate, distinct elastic laminate portions (10), each of which is positioned along at least a part of the opening, e.g. such that at least one laminate portion (10) is positioned and extends along each longitudinal edge of the opening, or part thereof, as described herein after.
The topsheet (20) may consist of a (supporting) topsheet material and the elastic material (s) (12) or it may comprise other components, such as for example attachment means, attachment sheets, coverstrips (13) etc.
The elastic laminate portion (10) may be formed from the topsheet material (13) or part thereof, an elastic material (12) and optionally additional components, such as adhesive (14) or an attachment sheet positioned between the topsheet (20) and the elastic material (12), and/or an additional cover-strip (13) that covers the opposite side of the elastic material, e.g. so that the elastic material may be sandwiched between two layers of topsheet materials, or between an attachment sheet and topsheet material(s), and/or a cover-strip (13).
A preferred disposable absorbent articles of the invention is a diaper, including adult incontinent garments, pull-on or training diapers and baby or infant diapers with fasteners, as shown in the Figures, that may comprise an absorbent core (23); a liquid pervious core coversheet, positioned under the topsheet (20), on the absorbent core (23); a liquid impervious backsheet (21); optionally (elastic) side panels (27), (elastic) leg cuffs (25), (elastic) barrier cuffs (26), (elastic) waist feature (24), and a fastening system (28). The article as shown in
In preferred embodiments, the backsheet (21) is impervious to liquids (e.g., urine) and comprises a thin plastic film such as a thermoplastic film having a thickness of about 0.012 mm (0.5 mil) to about 0.051 mm (2.0 mils). Suitable backsheet films include those manufactured by Tredegar Industries Inc. of Terre Haute, Ind. and sold under the trade names X15306, X10962 and X10964. Other suitable backsheet materials may include breathable materials which permit vapors to escape from the article while still preventing exudates from passing through the backsheet. Exemplary breathable materials may include materials such as woven webs, nonwoven webs, composite materials such as film-coated nonwoven webs, microporous films.
The core coversheet is preferably compliant, soft-feeling, and non-irritating to the wearer's skin. Further, at least a portion of the core cover sheet is liquid pervious, permitting liquids to be absorbed by the absorbent core (23) underneath. A suitable core cover sheet may be manufactured from a wide range of materials, such as porous foams, reticulated foams, apertured plastic films, or woven or nonwoven materials of natural fibers (e.g., wood or cotton fibers), synthetic fibers (e.g., polyester or polypropylene fibers), or a combination of natural and synthetic fibers. If the core cover sheet includes fibers, the fibers may be spunbond, carded, wet-laid, meltblown, hydroentangled, or otherwise processed as is known in the art.
Any portion of the core coversheet or the topsheet (20) described herein may be coated with a lotion as is known in the art. Examples of suitable lotions include those described in U.S. Pat. No. 5,607,760 entitled “Disposable Absorbent Article Having A Lotioned Topsheet Containing an Emollient and a Polyol Polyester Immobilizing Agent” issued to Roe on Mar. 4, 1997. The lotion may function alone or in combination with another agent as the hydrophobizing treatment described above. The core coversheet and/topsheet (20) may also include or be treated with antibacterial agents, some examples of which are disclosed in PCT Publication No. WO 95/24173 entitled “Absorbent Articles Containing Antibacterial Agents in the Topsheet For Odor Control” which was published on Sep. 14, 1995 in the name of Theresa Johnson.
The absorbent core (23) may comprise any absorbent material which is generally compressible, conformable, non-irritating to the wearer's skin, and capable of absorbing and retaining liquids such as urine and other certain body exudates. The absorbent core may be manufactured in a wide variety of sizes and shapes (e.g., rectangular, hourglass, “T”-shaped, asymmetric, etc.) and may comprise a wide variety of liquid-absorbent materials commonly used in disposable diapers and other absorbent articles such as comminuted wood pulp, which is generally referred to as airfelt, and preferably at least superabsorbent polymers or absorbent gelling materials; or any other known absorbent material or combinations of materials. Preferred may be that the absorbent core comprises at least 80% by weight (based on the total content of material in the core, excluding the core wrap or cover sheet) of superabsorbent polymer or so-called absorbent gelling material.
The article may also include a fastening system (28) that maintains the first waist region and the second waist region in a configuration so as to provide lateral tensions about the circumference of the article to hold it on the wearer. The fastening system (28) preferably comprises a surface fastener such as tape tabs, hook and loop fastening components and/or hermaphroditic fastening components; although any other known fastening means are generally acceptable. In alternative embodiments, opposing sides of the article may be seamed or welded to form a pant. This allows the diaper to be used as a pull-on type diaper or training pant. Training pants are placed in position on the wearer by inserting the wearer's legs into the leg openings and sliding the training pant into position about the wearer's lower torso.
The article may also comprise side panels (27) that are preferably elastic or non-elastically extensible to provide a more comfortable and contouring fit by initially conformably fitting the article to the wearer and sustaining this fit throughout the time of wear well past when it has been loaded with exudates since the elasticized or extensible side panels allow the sides of the article to expand and contract.
The article may include a pair of longitudinally extending, transversely spaced apart barrier cuffs (26), and/or longitudinally extending, transversely spaced apart leg cuffs (25), which provide improved containment of liquids and other body exudates. Said leg cuffs and/or barrier cuffs may also comprise the elastic laminate portion (10) as described herein below
Topsheet (20) with the Elastic Laminate Portion(s) (10)
The topsheet (20) comprises at least one elastic laminate portion (10), but in one embodiment it preferably comprises at least two separate elastic laminate portions (10), as also shown in the
Each laminate portion (10) has in relaxed/contracted state and in partially stretched state, including at an elongation ε of 0.5 as described herein below, at least one surface with wrinkles that face the user's body and may be in contact with the skin in use. The elastic laminate portion (10) may comprise two or more (preferably non-elastic) sheets of material that are attached to either surface of an elastic material, and the laminate portion than typically contains wrinkles on either surface of the elastic laminate portion.
The properties of said wrinkles described herein applies at least to the wrinkles of the body-facing surface of the elastic laminate portion (10), but may apply to both surfaces of said laminate (10).
At an elongation ε of 0.5, whereby ε=(Lx−Lc)/Lc), said wrinkles are of an average wrinkle height (as measured by the “Primos” method set out below, using PRIMOS equipment) of less than 600 microns, and typically less than 600 but more than 200 microns, or between 550 microns and 300 microns, or up to 530, or even up to 500 microns. An exemplary Primos measurement graph of a section of an elastic laminate portion (10) as submitted by the test method herein is shown in
At an elongation ε of 0.5, the elastic laminate portions (10) herein may have an average wrinkle density (wrinkles per cm) of from 5 to 10 wrinkles per cm or even from 6 to 10, or even 7 to 10, or possibly only up to 9 wrinkles per cm, as measured with the Primos method set out below.
The elastic laminate portions (10) of the invention have an average maximum elongation εmax, (being (Ls−Lc)/Lc whereby Ls is the fully stretched length of the elastic laminate portion), of at least 0.8 or even more preferably at least 1.0 or even more preferably at least 1.2, or it may be at least 1.4. These values can be obtained by the method set out in the method section below. It should be understood that the topsheet (20) may comprise areas (typically of between 0.5 and 2 cm, or 0.8 and 1.5 cm) where an elastic material is attached to the topsheet material without providing in that area any elongation of at least 0.5, and there are then possibly not even any wrinkles present. It should be understood for the purpose of the invention that such areas where elastic material is present but that have an elongation of less than 0.5 are not considered part of the elastic laminate portion (10) herein. Such areas may herein be referred to as “attachment portions”.
In order to determine and obtain the elongation ε=0.5 of the elastic laminate portion (10), the elastic laminate portion's (10) absolute contracted length Lc, is first determined as follows.
The topsheet (20) with the elastic laminate portion (10) is removed from the absorbent article, or if possible the elastic laminate portion (10) is removed from the article, either way such that the wrinkle profile and elastic profile (i.e. of the upward facing surface that in use is facing the body of the user) is not changed.
The topsheet (20) or elastic laminate portion (10) is placed as flat as possible on a surface, without applying any elongating or stretching force to it. Then, the absolute contracted length of the elastic laminate portion (10) of the topsheet (20) is measured. This is herein referred to as the absolute contracted length of the laminate Lc.
Then, the length of the laminate portion (10) at ε=0.5 can be calculated, this being 1.5 Lc
(based on: ε=(Lx—Lc)/Lc).
Subsequently, the laminate portion (10) can be stretched by the method described herein below to obtain this elongation of 0.5 at 1.5 Lc. Then, the wrinkle heights, average wrinkle height and deviations, wrinkle width, distance between wrinkles, average wrinkle density and deviation thereof can be calculated by use of the Primos method, using PRIMOS equipment, as described below.
Typically, the elastic laminate portion (10) has wrinkles of a relatively or substantially uniform wrinkle height (distribution), at least on the body-facing surface of the elastic laminate portion (10). For example, less than 10% or preferably less than 5% of the wrinkles are 800 microns or more, preferably less than 10% or even less than 5% of the wrinkles are 700 or more, or even 650 microns or more; and it may even be possible that 95% or more, or even all wrinkles (about 100%) have a height of less than 600 microns.
Furthermore, it may be preferred that the wrinkle density is substantially uniform throughout an elastic laminate portion e.g. that in no section of 2 cm (in length direction, along the laminate portion) the wrinkle density is more than 12 and that in no section of 2 cm (in length direction, along the laminate portion) the wrinkle density is less than 3, or less than 4. (Preferred may be that in each 2 cm section of a laminate portion (10) the wrinkle density is between 5 and 10, or any of the preferred values described above.
The width of the elastic laminate portions (10) will vary, typically depending on the exact dimensions of the topsheet (20) and/or of the article.
For example, for size 4 diapers the elastic laminate portion (10) in a topsheet (20) herein may, in fully stretched state, have an average width of about 3 mm to 50 mm, preferably 3 mm to 40 mm, or even more preferably 3 mm, or even 5 mm to 20 mm.
The elastic materials (12) used herein are typically very thin, typically having a thickness or caliper (e.g. gauge) of typically up to about 200 microns, or even up to 150 microns or even up to 110 microns, or up to 100 microns and they may need to be at least 20 microns, more preferably at least 40 microns, or even at least 60 microns, as defined herein. Highly preferred materials have a thickness of about 70 to 100 microns.
A suitable elastic material is for example 2L-89, available from Fulflex, (Limerick, Ireland).
The topsheet (20) herein has at least one opening, or only one such opening, and said opening(s) may be in the form of a (single) slit opening, as shown in
The dimensions and exact shape of the opening(s) may vary, depending on the size of the topsheet (20) and/or the absorbent article. For example, in a preferred embodiment the opening is in the form of a slit opening with substantially parallel longitudinal side edges, which are connected in the front and/or back by V-shaped or U-shaped edges. In a preferred embodiment, the front V-shaped edges have a larger angle than the back V-shaped edges. Preferably, the front V-shaped edges have an angle of 20° to 140°, preferably from 45° to 65°, most preferably from 55° to 60°, as described herein after and can be seen from
The maximum length of the slit opening may be for example 40% to 90% or more preferably 50% to 80%, or even more preferably about 60% to 70%, of the total fully stretched length Ls of the absorbent article.
Preferred may be, in particular for size 4 diapers with a maximum topsheet (20) length of between 45 cm and 55 cm, typically between 48 cm and 52 cm, that the length of the single slit opening, when the diaper is in fully stretched state, is from 20 cm to 40 cm, or even from 25 cm to 35 cm, or even from 28 cm to 32 cm.
The average width of the opening herein, in fully stretched state, is preferably from 5% to 30%, or more preferably 10% to 25%, of the average width of the topsheet (20) (including opening width), or for example for a size 4 diaper, 15 mm to 60 mm, more preferably from 20 mm to 40 mm.
The topsheet (20) comprises in one embodiment herein at least two elastic laminate portions (10), to form typically a pair of opposing, preferably at least partially parallel and/or at least partially longitudinally extending elastic laminate portions (10), (elasticated areas), or preferably mirror image elastic laminate portions (10), such as described in copending application EP-A-1201212, and shown in
The elastic laminate portion (10) extends preferably along the longitudinal side edges of the opening(s) towards or completely to the front and/or back transverse edge of the topsheet (20). Thus, the elastic laminate portions (10) are preferably longer than the opening. Preferred is that the elastic laminate portions (10) are positioned over the full length of the topsheet (20), or at least the part of the topsheet (20) which in use is intended to receive body exudates, typically the topsheet (20) minus the parts thereof which form (part of) the waist bands, if present.
The elastic laminate portion (10) is preferably shaped such that it has a centre portion that is substantially parallel to the centre portion of the opposing elastic laminate portion (10).
Each of the two centre portions has a length, which is preferably 30% to 70% of the total fully stretched length Ls of a corresponding elastic laminate portion (10), and preferably about 40% to 80% of the maximum length of the opening; hereby, it is preferred that the total length of the elastic laminate portion (10) is about 70% to 90%, or preferably from about 80% to 90% or preferably about 85% of maximum length of the topsheet (20).
Preferred is that the front end portions of two opposing elastic laminate portions (10) bend away from one another (in the plane of the topsheet (20)), so that the distance between the end edges of the opposing front end portions of two opposing elastic laminate portions (10) is larger that the distance between the centre portions of two opposing elastic laminate portions (10), and equally, the distance between the end edges of the opposing back end portions of two opposing elastic laminate portions (10) is larger that the distance between the centre portions of two elastic laminate portions (10).
The elastic laminate portion (10) is typically angled, as described herein, whereby it has a front and back angle with a longitudinal line through the centre straight part (or centre portion) of the elastic laminate portion (10) and parallel to the longitudinal axis of the topsheet (20), of between 10° and 40°, or preferably between 17° to 35°, or even more preferably between 20° and 35°.
Such pair of opposing, angled elastic laminate portions (10) are herein referred to, as having an X-shape, and a preferred X-shape is exemplified in
The free longitudinal edge of the elastic laminate portion (10) or the laminate portion (10) as a whole may have an average caliper (at a pressure of 0.33 psi and an elongation of 0.5) of 1.3 mm or less, or 1.1 mm or less, or 1.0 mm or less, or 0.95 mm (950 microns) or less, and it may be more than 0.4 mm (400 microns) or even for example more than 0.6 mm (600 microns), as measured with the method set out herein below.
Hereto, the elastic laminate portion (10) may comprise one or two (laminated) layers that each have a basis weight of 20 g/m2 or less, preferably one or two (laminated) layers of a basis weight of 17 g/m2 or less; provided that if two (laminated) layers are present, their combined basis weight may preferably be 34 g/m2 or less.
Typically, at least one topsheet material (13) forms part of the laminate portion (10), and hence, preferred is that at least one layer of the elastic laminate portion (10) is part of the topsheet material (13) or the topsheet (20) as a whole.
The topsheet (20) may also be made of two (laminated) layers, with therein between, in certain area(s), the elastic material (e.g. a so-called sandwich structure), as for example shown in
The topsheet (20) as a whole may typically have an average caliper that is the same or less than the caliper of the laminate portion (10).
The topsheet (20) and the elastic laminate portion (10) herein may comprise any sheet material suitable to be laminated to an elastic material (12). Preferably, the sheet material of the topsheet (20) and laminate portion (s) (10) is not itself elastically stretchable in y-direction.
The topsheet (20) is preferably air permeable. In certain executions herein, it may be preferably that it has high barrier properties. The topsheet (20) and the elastic laminate portion (10) is preferably hydrophobic and/or urine-impermeable.
Preferred topsheets (20) and elastic laminated portion(s) (10) thereof comprise woven and non-woven materials of natural fibers (e.g., wood or cotton fibers) and/or synthetic fibers. They comprise preferably thermoplastic polymer fibers, preferably selected from the group comprising: polyolefins, polyesters, polyurethanes, and polyamides, most preferably the thermoplastic polymer being a polyolefin, most preferably being polypropylene or polyethylene. The fibers may be spun bond, carded, wet-laid, melt blown, and/or hydro entangled, and/or otherwise processed as is known in the art. Preferred is that the topsheet (20) and laminate portion (10) thereof comprises one or more nonwoven material sheets that is itself a laminate of layers of meltbown and carded or spunbond material. For example, a sheet or layer of the topsheet may be a laminate of at least two layers, one of which at least is a meltblown (M) layer and one of which is at least a spunbond (S) or a carded (C) layer.
Preferred executions are SM SMS, SMMS, SSMS, SSMSS, SSMMS, CM or CMC non-wovens laminates.
Most preferably, said non-woven webs are formed from polyethylene, polypropylene and/or polybutylene polymer fibers, or (a mixture of) fibers of a copolymers of polyethylene, polypropylene and/or polybutylene; most preferred are polypropylene polymer fibers.
It may also be preferred that the topsheet (20) comprises ingredients, which reduce friction between the wearer's skin and the topsheet (20), or in particular between the skin and the elastic laminate portion (10). Hereto, the laminate portion (10) or topsheet (20), may for example comprise a lotion, a fine powder, such as talcum powder, or wax.
The topsheet (20) or laminate portion (10) may be treated with an agent to reduce its surface energy. For example useful agent include fluorocarbons as described in U.S. Pat. No. 5,876,753, issued to Timmons et al. on Mar. 2, 1999; U.S. Pat. No. 5,888,591 issued to Gleason et al. on Mar. 30, 1999; U.S. Pat. No. 6,045,877 issued to Gleason et al. on Apr. 4, 2000. Other agents include silicone. Useful methods for applying the agent to the material, without reducing the air permeability, can be found in U.S. Pat. No. 5,322,729 and PCT Publication WO 96/03501. Preferred agents may be selected from the group comprising fluorocarbons, siloxanes, polysiloxanes, preferably including fluorinated monomers and fluorinated polymers, including hexafluoroethylene, hexafluoropropylene and vinyl fluoride and vinylidene fluoride, fluoroacrylate and fluoromethacrylate. Highly preferred is that the topsheet (20) is provided with poly (tetra) fluoroethylene, fluorinated ethylene-propylene copolymers and/or fluorinated ethylene-tetrafluoroethylene copolymers.
The topsheet (20) with the elastic laminate portion (10) and/or the laminate portion (s) (10) herein are such they typically have one of the following elastic profiles:
a) 1.5 Lt by a first load force of less than 1.1N or even less than 0.6N, 3.0 Lt by a first load force of less than 2.1N or even 1.1N and 4.5 Lt by a first load force of less than 3.0N or even less than 1.5N and a second unload force at 4.5 Lt of more than 0.9N, a second unload force at 3.0 Lt of more than 0.5N and a second unload force at 1.5 Lt of more than 0.1N.
(Said elastic profile obtainable by the method set out in co-pending application EP1201212-A, whereby Lt is the contracted length of the topsheet (20) or elastic laminate portion (10), which ever applicable, herein referred to as Lc).
or:
b) 0.25 Ls by a first load force of less than 0.6 N, 0.55 Ls by a first load force of less than 5N or even less than 3.5 N and 0.8 Ls by a first load force of less than 10.0N or even less than 7.0N and a second unload force at 0.55 Ls of more than 0.4N, and a second unload force at 0.80 Ls of more than 1.4N, or even more than 2.0N.
(Said elastic profile obtainable by the method set out in co-pending application EP1201212-A, whereby Ls is as specified herein, being the fully stretched length of the elastic laminate portion (10) or topsheet (20), which ever is applicable.)
Preferably, the topsheet (20) and/or elastic laminate portion (10) has a force profile such that it has a first load force at 200% elongation of 1.6 N or less, and a second unload force at 200% elongation of 0.5 N or more.
The elastic material (12) may be attached to one or more of the supporting sheet(s) or layers or nonwoven(s) that form the elastic laminate portion (10) or typically the topsheet, by any method, including adhesive bonding and ultrasonic bonding, but preferred may be the use of adhesive (14). The adhesive (14) may be applied such that the required wrinkle density and wrinkle heights are achieved, as also claimed herein.
Preferred is that the elastic material (12) is attached to the topsheet and/or to other material comprised in the elastic laminate portion by use of a specific pattern that is suitable to obtain the wrinkle heights and densities referred to herein, said pattern having providing attachment areas (14) and non attachment areas therein between, as for example shown in
Preferred may be that the elastic laminate portion (10) has, at fully stretched absolute state with length Ls, substantially transverse attachment areas (14) such that the average distance between neighboring transverse parts of the attachment area(s) (14) is from 0.3 mm to 2.5 or to 2.0 mm, or preferably from 0.6 to 1.2 mm. Preferred may be that the average width (substantially in the direction of stretch), of the transverse parts (in the elastic laminate portion (10) at said fully stretched state), is from 0.2 mm to 1.2 mm, or preferably from 0.3 mm to 0.8 mm. or even 0.5 or less.
For example, the attachment means may include a uniform continuous layer of adhesive (14), a patterned layer of adhesive (14), or an array of separate lines, spirals, “omega” shaped line(s), or spots of adhesive (14). The adhesive (14) may for example be applied in an intermittent stripe pattern, preferably straight stripes that are positioned in (substantially) transverse direction along the elastic laminate portion, e.g. substantially perpendicular to the longitudinal direction of the elastic laminate portion (10), as shown in
Preferred may be that the ratio of the average width of the stripes to the average distance between neighboring stripes (ratio Radhesive) is from about 4:10 to 8:10 or 6:10, or for example about 1:2
The adhesive (14) may also be applied in a so-called omega pattern, as shown in
Test Methods:
Method to Stretch the Elastic Laminate Portion (10) to an Elongation of ε=0.5;
Method to Determine its Fully Stretched Length Ls and εmax
The elastic laminate portion (10) may be straight, curved, or it may comprise several straight parts that are joined under one or more angles with one another, as can been seen in
In each case below, a sample (e.g. topsheet. or preferably an elastic laminate portion thereof, if this can be isolated as such) is obtained from an absorbent article that has been conditioned for 24 hours at 50% humidity and 23 C.
1) When the Elastic Laminate Portion (10) is Straight:
The elastic laminate portion (10) or topsheet as a whole is obtained and put on a flat surface as described above to measure the contracted length of the elastic laminate portion (10) Lc.
The elastic laminate portion is subsequently elongated to 1.5 Lc (equals ε=0.5) or to its fully stretched length Ls, to determine εmax as follows.
The sample (the topsheet with the elastic laminate portion or the elastic laminate portion thereof) is left for 24 hours at 25° C. and 50% humidity, prior to the elongation/stretching step below, which is subsequently performed under the same conditions.
Measurement of lengths of the samples can be done with a micrometer screw.
The sample to be tested is placed length-wise (in the direction of stretch) between two tweezers or, if the width of the sample is more than 1 cm, between two clamps of a width of 1 cm, one on each end, such that contact area of the tweezers/clamp and the sample is at the most 1 mm for clamps and 0.5 mm for tweezers in the direction of stretch (length). The exact distance between the start of one clamp or tweezers to the beginning of the other clamp or tweezers is measured. This is the contracted length of the sample, e.g. of the laminate portion.
For straight samples, the clamps or tweezers are moved in the y-direction of the length of the straight samples, such that the length direction is the direction of the elongation force.
The sample may thus be stretched to its maximum elongation (e.g. when the supporting topsheet material (13) reaches its maximum length) and the length of the sample and the distance between the clamps is measured, and the elongation εmax is calculated.
Alternatively, the sample is stretched to ε=0.5, in order to submit the thus stretched sample to the Primos method set out below.
2) When the Elastic Laminate Portion (10) is “Angled”:
The elastic laminate portion (10) is divided by marking with a fine marker pen into straight parts (i.e. between the angles), for example in 3 straight parts. The sample is prepared and conditioned as described above.
Subsequently, each straight part is elongated separately by the method set out above for straight elastic laminate portions (10) to either ε=0.5 or εmax, e.g. when the sample comprises two angles and 3 straight parts, 3 force lines are determined and the sample is stretched 3 steps.
3) When the Elastic Laminate Portion (10) is Curved:
The curved elastic laminate portion (10) is divided with a fine marker pen into sections of 2 cm absolute length and possibly one remaining section of a smaller length. The sample is prepared and conditioned as described above.
Prior to elongation, the force line of each section of 2 cm (or one section of less than 2 cm) is determined as follows. Each section has two transverse edge lines that are 2 cm apart, and each transverse edge line has a centre point. A line can be drawn through said two points of said two transverse edge lines. This will be the “y-direction line” or force line along which the force will be applied to elongate said section. This will be done for each section.
Subsequently, each section is elongated separately by the manner set out above for straight elastic laminate portions (10), but by separately elongating each section along its own force line, to either ε=0.5 or its maximum elongation εmax.
After stretching all sections, a fully stretched absolute length can be measured for each section and for the elastic laminate portion (10), Ls and εmax can be calculated.
4) Mixed Elastic Laminate Portion (10)
If the elastic laminate portion (10) comprises a combination of curved, angled and/or straight parts, then a combination of the above methods is applied accordingly.
Primos Method:
Determination of the Wrinkle Heights and Density, Averages and Deviations Thereof
The following described the method to determine the wrinkle height and winkle density of the laminate portion (10) of the topsheet (20).
Each sample with the elongation of 0.5 as defined and obtained by the method described herein, is examined by use of PRIMOS equipment and its data acquisition software, following the manufacture's instructions manual, using a 13×18 mm lens.
If the elastic laminate portion (10) has an average width of more than 3 mm, then the measurement above is only done on the inner 70% of the width of the laminate portion, along its length.
The PRIMOS equipment will provide graphs per measured section of the sample, as shown in
Caliper Measurement
The caliper and average caliper of an elastic laminate portion (10) that has an elongation of ε=0.5, as described herein, can be obtained by use of a micrometer, such as the Frank 16303, obtainable from Twing Albert-Frank GmbH. The test is done at 23° C., 50% humidity. The sample should be already conditioned to this humidity and temperature as set out above, since it has been conditioned for 24 hours under these conditioned, prior to stretching it to the required elongation of 0.5, needed to do this caliper test. The equipment is calibrated prior to testing. The lowering speed of the pressure foot is set to be 3 mm/sec and the dwelling time 2-5 sec.
The size (surface area) of the anvil is chosen depending on the size of the elastic laminate potion (10), and subsequently the weight on the pressure foot is chosen such that the required pressure of 0.33 psi is obtained.
For example, an anvil with a 40 mm diameter is used and a total weight of 295 grams (80 grams of the pressure foot plus an additional 115 grams) is applied to measure preferred elastic laminate portion(s) (10) herein.
To obtain the average caliper of the elastic laminate portion, the test is repeated on several portions of the elastic laminate portion, such that the areas pressed by the anvil per measurement do not overlap. Subsequently, an average can be calculated. Also the deviation in the caliper can be calculated.
All documents cited in the Detailed Description of the Invention are, in relevant part, incorporated herein by reference; the citation of any document is not to be construed as an admission that it is prior art with respect to the present invention. To the extent that any meaning or definition of a term in this written document conflicts with any meaning or definition of the term in a document incorporated by reference, the meaning or definition assigned to the term in this written document shall govern.
While particular embodiments of the present invention have been illustrated and described, it would be obvious to those skilled in the art that various other changes and modifications can be made without departing from the spirit and scope of the invention. It is therefore intended to cover in the appended claims all such changes and modifications that are within the scope of this invention.
| Number | Date | Country | Kind |
|---|---|---|---|
| 05113019.3 | Dec 2005 | EP | regional |
