Underwear Article Comprising An Elastic Laminate

CROSS-REFERENCE TO RELATED APPLICATIONS

0001The present application is a continuation of PCT/SE2005/000318, filed on Mar. 2, 2005, and which designates the U.S. The entire contents of PCT/SE2005/000318 are incorporated herein by reference.

TECHNICAL FIELD

0002The present invention refers to a pant type underwear article, said article comprising front, back, crotch and waist regions. At least part of the article comprises an elastic laminate composed of two layers of fibrous material and an elastic film layer located between the fibrous layers.

BACKGROUND

0003It is known to hold disposable absorbent bodies in place against the body of an incontinent wearer with reusable pant-type underwear articles. The disposable absorbent bodies may be sanitary napkins or incontinence articles. This approach has advantages over conventional absorbent articles with an integral absorbent core such as diapers or incontinence pants, in that only the absorbent component of the article is disposed after soiling, while the underwear component can be reused, thus providing savings in both manufacturing costs and materials.

0004Laminate-type materials are known as components of absorbent articles such as diapers. For example, WO 03/047488 discloses an elastic laminate comprising an elastic film which on opposite sides is bonded to first and second non-elastic fibrous layers. The laminate is made by bonding the non-elastic fibrous layers to the elastic film layer and subsequently stretching the composite material, causing the non-elastic materials to break. The elastic film material may be of a breathable material. The laminate may be incorporated in an absorbent article, such as a diaper. No mention is made of the puncture resistance of such a material. The process described in WO 03/047488 will give a material which is soft and elastic, but which on the other hand has low resistance to puncturing, as the broken outer nonwoven layers will make no contribution to the puncture resistance of the laminate.

0005EP0861647 discloses an underwear system comprising a reusable underpant part and an exchangeable absorber lining. The pants consist of a 3-layer laminate, which contains a membrane film as an intermediate layer between two textile structures.

0006Elastic materials, such as stretch-bonded laminates, are also known. Such laminates may include a layer of meltblown elastomeric fibers which have been stretched and sandwiched between outer layers of spunbonded webs.

0007US2003/0022582 describes a laminate in which an elastomeric film is bound between two or more layers of nonwoven webs. The laminate is said to be particularly useful in elastic “ears” of diapers, which allow the diaper to be stretched to accommodate variously sized wearers. It is stated that nonwoven materials provide little or no puncture resistance, hence any puncture resistance which the laminate has will be almost exclusively due to the puncture resistance of the elastomeric film.

0008However, there is room for improvement of the underwear articles used in two-component systems. The consumer places high demands on the comfort, fit and cloth-like feel of the pant-type underwear articles. Discreteness of the article is also a high priority, so the underwear article should be thin, preferably equally as thin as a pair of ordinary cotton pants. Furthermore, it is highly desirable that the absorbent body is held correctly in position against the wearer's body by the underwear article, so that it is optimally positioned to receive body exudates and undesired slippage or movement of the absorbent body is avoided. The underwear article itself is intended to be re-used, and therefore requires washing. It must therefore be able to tolerate the elevated temperatures, water, detergents and mechanical agitation which are present in the washing and/or drying machines of today without breaking. There is therefore a need for improvement of the strength of underwear articles, particularly their resistance to puncture.

OBJECT AND SUMMARY

0009One object of the present disclosure is to provide a pant-type underwear article which combines the properties of comfort and fit to the wearer's body and a soft and cloth-like feeling close to textile materials. It is further desirable that the article can be put on and taken off without puncturing, e.g. by fingernails. This is an important feature, as the force which can be applied during putting on and taking off such an article has been estimated as being up to 5N. It is also an object that the article should tolerate machine washing and drying and remain intact. These and further objects have been accomplished by a pant-type underwear article comprising front, back, crotch and waist regions, at least part of said article comprising an elastic laminate composed of first and second layers of fibrous material and an elastic film layer located between said first and second fibrous layers. The elastic laminate has a puncture resistance of at least 15N.

0010Due to the materials and methods involved in its construction, the puncture resistance of this laminate is higher than the elastic film layer alone (i.e. the layers of fibrous material contribute to the puncture resistance of the laminate). The underwear article provides good fit due to the elasticity of the laminate, and a cloth-like feel. Furthermore, the underwear article is reusable, and tolerates machine washing/drying, even machine washing up to 60° C. Use of the laminate allows the article to survive machine washing at least three times at up to 60° C. through a washing cycle of a washing machine and yet remain intact. The underwear article may be used to hold individual absorbent bodies (e.g. sanitary napkins or incontinence articles) securely in place against the user's body, yet will not be permanently fastened to such absorbent bodies. The elastic properties of the laminate help to ensure that the absorbent bodies are held securely against the wearer's body.

0011Preferably the elastic laminate has a puncture resistance of at least 20N, more preferably at least 30N.

0012In one embodiment, at least the front region of the article comprises the elastic laminate. Furthermore, both the front and back regions of the article may comprise the elastic laminate. In another embodiment, a substantial part of the crotch region of the article is free from elastic laminate. Additionally, the waist region of the article may be free from elastic laminate. In a separate embodiment, the entire article comprises the elastic laminate.

0013Preferably, the elastic film layer is breathable. The elastic laminate suitably has a Water Vapour Transmission Rate according to ASTM E96-00 Procedure D of at least 1500 g/m²24h, preferably at least 3000 g/m²24h.

0014In one embodiment, the elastic laminate has an elasticity in the transverse direction of the article of at least 30%, preferably at least 50%, more preferably 70%, when measured according to the elasticity test specified herein. Elasticity in the transverse direction of the article allows an article of a single size to be used on wearers having a variety of waist sizes. At least one of the layers of fibrous material may have an elongation at maximum load greater than the elasticity of the elastic laminate. Furthermore, both layers of fibrous material may have an elongation at maximum load greater than the elasticity of the elastic laminate.

0015According to one embodiment, the layers of fibrous material have an elongation at maximum load of at least 10%, preferably at least 20% greater than the elasticity of the elastic laminate. The first and/or the second layers of fibrous material preferably comprise a mixture of polypropylene and polyethylene polymers.

0016In a most preferred embodiment, the elastic laminate comprises first and second fibrous layers of spunbond material, each having a basis weight of between 10 and 35 g/m², preferably between 12 and 30 g/m², more preferably between 15 and 25 g/m²and a breathable elastic film layer having a basis weight between 20 and 100 g/m², preferably between 20 and 60 g/m², said elastic laminate having a Water Vapour Transmission Rate according to ASTM E96-00 Procedure D of at least 1500 g/m²24h, preferably at least 3000 g/m²24h.

DESCRIPTION OF THE FIGURES

0017<figref idref="DRAWINGS">FIG. 1</figref> shows a perspective view of a pant-type underwear article according to an embodiment of the present invention.

0018<figref idref="DRAWINGS">FIG. 2</figref> shows is a simplified plan view of the pant-type underwear article in its flat, uncontracted state prior to formation.

0019<figref idref="DRAWINGS">FIG. 3</figref> is a cross section through an elastic laminate according to an embodiment of the invention.

0020<figref idref="DRAWINGS">FIG. 4</figref> is a graph showing load vs. strain for two nonwoven fibrous layers.

0021<figref idref="DRAWINGS">FIG. 5</figref> is a graph showing load vs. strain for an elastic laminate.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

0022The figures show an embodiment of a pant-type underwear article <b>10</b>. The article typically comprises front <b>12</b>, back <b>14</b>, crotch <b>16</b> and waist <b>18</b> regions. The front region <b>12</b> is that which in use covers the belly of the user. The waist region <b>18</b> is that which encircles the waist of the user when the article is being worn. The back region <b>14</b> is that which covers the lower torso/buttocks of the user when the article is being worn. The crotch region <b>16</b> is defined as the narrow part of the article intended to be worn in the wearer's crotch between the legs. The article <b>10</b> has a longitudinal (y) and a transverse direction (x).

0023The article is thus divided into four regions (front region <b>12</b>, back region <b>14</b>, crotch region <b>16</b> and waist region <b>18</b>) in its longitudinal direction, as shown in <figref idref="DRAWINGS">FIG. 2</figref>. The front region is defined by the edge of the article at which the waist region ends, the longitudinal side edges of the article, part of the leg openings of the article and a transverse line (a) which is located at the point at which the angle of the edge of the leg opening changes most abruptly (i.e. the point at which the rate of change of the angle of the edge of the leg opening with respect to the transverse direction is highest). The back region is defined in a similar manner: by the edge of the article at which the waist region ends, the longitudinal side edges of the article, part of the leg openings of the article and a transverse line (b) which is located at the point on the edge of the leg opening at which the angle of the edge changes most abruptly (i.e. the point at which the rate of change of the angle of the edge of the leg opening with respect to the transverse direction is highest). The crotch region is defined at its longitudinal edges by the edges of the leg openings of the article and at its transverse edges by the two transverse lines (a) and (b) described above.

0000Elastic Laminate

0024At least part of the article <b>10</b> comprises an elastic laminate <b>20</b> composed of first <b>22</b> and second <b>24</b> layers of fibrous material and an elastic film layer <b>26</b> located between said first and second fibrous layers <b>22</b>; <b>24</b>. Characteristically, the elastic laminate <b>20</b> has a puncture resistance of at least 15N. Preferably, the elastic laminate <b>20</b> has a puncture resistance of at least 20N, more preferably at least 30N.

0025The laminate is elastic at least in the transverse x-direction of the article. The elasticity in the x-direction should be at least 30%, preferably at least 50%, more preferably at least 70%, as measured by the elasticity test specified herein.

0026The elastic laminate <b>20</b> is composed of first and second outer layers of fibrous material <b>22</b> and <b>24</b> and a middle elastic film layer <b>26</b> located between said fibrous layers. The outer fibrous layers <b>22</b> and <b>24</b> are chosen so that they, in combination with the inner elastic film layer, give the laminate high resistance to puncture. They also provide a soft and cloth-like feel to the laminate. Examples of suitable materials are carded webs and spunbond materials. The basis weight of the fibrous material layers should be between 10 and 35 g/m², preferably between 12 and 30 g/m², more preferably between 15 and 25 g/m². Examples of suitable polymers used in the fibrous materials are polyethylene, polyesters, polypropylene and other polyolefin homopolymers and copolymers. Natural fibres, for example cotton, may also be used as long as they provide the required properties. A mixture of polymers can contribute to a higher flexibility of the nonwoven layer, and through this, give the nonwoven material a higher elongation at maximum load. A mixture of polyethylene and polypropylene polymers has proved to provide good results in this respect. A mixture of fibers of different polymers is also possible.

0027The middle elastic film layer <b>26</b> is according to one embodiment of the invention an apertured elastic film having a basis weight between 20 and 100 g/m², preferably between 20 and 60 g/m². The film may be of any suitable elastic polymer, natural or synthetic. Some examples of suitable materials for the elastic film are low crystallinity polyethylenes, metallocene-catalyzed low crystallinity polyethylene, ethylene vinyl acetate copolymers (EVA), polyurethane, polyisoprene, butadiene-styrene copolymers, styrene block copolymers, such as styrene/isoprene/styrene (SIS), styrene/butadiene/styrene (SBS), or styrene/ethylene-butadiene/styrene block copolymer. Blends of these polymers may also be used as well as other modifying elastomeric or non-elastomeric materials. One example of a suitable film is an apertured three-layer elastomeric film of PE-SEBS-PE.

0028As mentioned previously, the elastic film layer <b>26</b> may be breathable. This allows a higher degree of comfort for the wearer, as moisture/humidity build-up is reduced or completely avoided. The breathability of the elastic film layer <b>26</b> may be quantified by the Water Vapour Transmission Rate (WVTR) according to ASTM E96-00 Procedure D. According to one embodiment, the elastic laminate <b>20</b> has a Water Vapour Transmission Rate of at least 1500 g/m²24h, preferably at least 3000 g/m²24h as measured by the above ASTM procedure.

0029The elastic laminate <b>20</b> may be manufactured according to a modified version of the method disclosed in WO 03/047488, wherein one spunbond layer <b>22</b> is applied to the film <b>26</b> in a tacky state and will thus bond to the film layer, while the other spunbond layer <b>24</b> is adhesively laminated to the film layer <b>26</b>, using for example a pressure sensitive hot melt adhesive. The modification involves the laminate being incrementally stretched (through intermeshing gears, IMG), to a point below the elongation at peak load of at least one of the non-elastic nonwoven layers to retain some strength for at least one of the nonwoven layers. The other layer may also be stretched to a point below its elongation at peak load, or to a point at which it will tear during stretching.

0030The method disclosed in WO 03/047488 involves stretching of the laminate above the point of failure of the fibrous material, so that the non-elastic layers break completely. Therefore, as described in WO 03/047488, the elongation of the laminate is not limited by the stretch modulus of the non-elastic material.

0031In contrast to the method described in WO 03/047488, upon manufacture of a laminate according to an embodiment of the present invention, at least one, preferably both fibrous layers which are bound to the elastic film are not completely torn. Selection of fibrous materials which have an elongation at maximum load greater than the elasticity of the elastic laminate allows the elastic film to stretch without being hindered by the fibrous layers. Such a selection also ensures that the fibrous layers contribute to the puncture resistance of the laminate, as they are not completely torn or broken during manufacture. Therefore, at least one of—alternatively both—the layers of fibrous material <b>22</b>, <b>24</b> may have an elongation at maximum load greater than the elasticity of the elastic laminate <b>20</b>. Preferably the layers of fibrous material <b>22</b>; <b>24</b>, or at least one of the fibrous layers, have an elongation at maximum load that is at least 10%, preferably at least 20%, greater than the elasticity of the laminate <b>20</b>.

0032According to a most-preferred embodiment of the invention, the elastic laminate <b>20</b> comprises first and second fibrous layers <b>22</b>, <b>24</b> of spunbond material, each having a basis weight of between 10 and 35 g/m², preferably between 12 and 30 g/m², more preferably between 15 and 25 g/m²and a breathable elastic film layer <b>26</b> having a basis weight between 20 and 100 g/m², preferably between 20 and 60 g/m². The elastic laminate <b>20</b> according to this embodiment has a Water Vapour Transmission Rate according to ASTM E96-00 Procedure D of at least 1500 g/m²24h, preferably at least 3000 g/m²24h.

0033<figref idref="DRAWINGS">FIG. 4</figref> shows the behaviour of two 20 gsm and 25 gsm nonwoven layers (BBA Sofspan 200) under stretching. It can be seen that, with increasing load (in Newtons), the strain in the layer increases, first slowly and then more rapidly. The applied load eventually reaches a maximum (the “maximum load”), at which point the load drops rapidly as the material fails. It can be seen that for the 20 gsm layer, maximum load is reached at around 90% strain, while for the 25 gsm layer, maximum load is reached at around 150% strain.

0034<figref idref="DRAWINGS">FIG. 5</figref> shows the behaviour of a laminate according to the present invention under stretching at a constant strain. The laminate comprises 25 gsm Sofspan NW from BBA on both sides of a 40 gsm apertured elastic film, where one face is glue-laminated with approximately 5 gsm glue.

0035From zero strain, the laminate exhibits elastic behaviour in region (A) up to around a “knee point” (B), after which, the load increases rapidly through region (C). The knee point (B) is defined as the first point on the load-strain curve at which the gradient becomes greater than 0.3N/%. The laminate shown is elastic up to about 80% strain—as this is less than the elongation (strain) at maximum load of the nonwoven layer (ca. 150% from <figref idref="DRAWINGS">FIG. 5</figref>), the laminate falls within the present invention.

0036The applied load eventually reaches a maximum (the “maximum load”, D), at which point the gradient of the load-strain curve is zero. The load then drops through region (E) as the material fails. Complete failure of the laminate occurs at point (F).

0037It is preferred that the elastic laminate <b>20</b> has a breathability (Water Vapour Transmission Rate) according to ASTM E96-00 Procedure D of at least 1500 g/m²24h, preferably at least 3000 g/m²24h.

0038The opacity of a material layer is the characteristic ability of the material layer to visually hide from view an underlying object or pattern. The opacity is measured in %, wherein 100% opacity means that nothing can be seen through the material layer and 0% means that the material layer is completely transparent. The opacity is measured by the Opacity Test described below, which is based on luminous-reflectance-factor data. The elastic web material has an opacity of at least 40%, preferably at least 50% and more preferably at least 60%. The opacity of the elastic web material provides a cloth-like appearance to the article, which is of particular importance when the article is pant-type underwear. Especially in this case, where the elastic web material forms the sole component in large areas of the front and back regions, the appearance of the elastic web material is of great importance for the overall appearance of the article. Thus by making the elastic web material opaque with an opacity of at least 40%, the pant-type underwear article will appear more cloth-like and more like “normal” underwear, than if the elastic web material has a higher degree of transparency.

0039Opacity can be increased by the incorporation of opacifying fillers into the laminate, particularly into the elastic film. Such pigments can be organic or inorganic dyes, colouring agents, or whitening agents. Inorganic materials such as titanium dioxide, inorganic carbonates, synthetic carbonates, talc, nepheline syenite, magnesium hydroxide, aluminium trihydrate siatomaceous earth, mica, natural or synthetic silicas, calcinated clays and mixtures thereof are preferred examples of opacifying fillers.

0040The filler is preferably added as a master batch at the extrusion of the film. One example of an appropriate concentration is about 5% filler by weight of the film.

0041The open area of the elastic film layer is preferably at least 5%, more preferably at least 8%. The open area is measured by image analysis methods and is defined as the sum of the hole area divided by the total area of the film sample.

0000Pant-Type Underwear Article

0042The pant-type underwear article <b>10</b> disclosed in <figref idref="DRAWINGS">FIG. 1</figref> is intended to enclose the lower part of the wearer's trunk and crotch region. It comprises front <b>12</b>, back <b>14</b>, crotch <b>16</b> and waist regions <b>18</b>. The front <b>12</b> and back <b>14</b> regions are joined to each other along their longitudinal edges at side seams <b>28</b>, which may comprise ultrasonic welds, glue strings or the like.

0043The entire article <b>10</b> may comprise elastic laminate <b>20</b>. Preferably, at least the front region <b>12</b> of the article <b>10</b> comprises the elastic laminate <b>20</b>. Furthermore, both the front and back regions <b>12</b>; <b>14</b> of the article may comprise the elastic laminate <b>20</b>.

0044According to a preferred embodiment a substantial part of the crotch region <b>16</b> of the article is free from the elastic laminate <b>20</b>. A “substantial part” used herein refers to at least 50%, preferably at least 75%. If the crotch region <b>16</b> does not comprise elastic laminate <b>20</b>, it may comprise nonwoven material, or a breathable film material. This embodiment allows improved comfort and breathability of the article in the crotch region. Alternatively, the crotch region <b>16</b> may comprise a different nonwoven film laminate than the elastic laminate <b>20</b> used in the remainder of the article. As a further alternative, the crotch region <b>16</b> may comprise a plastic film material, which may be non-breathable.

0045Preferably also the waist region <b>18</b> of the article is free from the elastic laminate. The waist region <b>18</b> may comprise a nonwoven material that is elasticized by elastic members <b>30</b>, such as elastic threads, contractably affixed between material layers, such as nonwoven materials. Such elastic members <b>30</b> may also be arranged around the leg openings of the article. Ultrasonic welds, glue strings or the like, join the elastic laminate <b>20</b> to the elasticized nonwoven in the waist region <b>18</b>.

0046No additional elasticized side panels joining the front and back regions <b>12</b> and <b>14</b> are needed when using the elastic laminate <b>20</b> according to the invention. If desired, additional elasticized side panels may of course be provided, especially in cases where the elastic laminate <b>20</b> is arranged only in parts of the front and/or back regions.

0047The elastic laminate should have a puncture resistance of at least 15N as measured according to ASTM Designation D3763-02. Preferably, the elastic laminate of the present invention has a puncture resistance of at least 20N, and more preferably at least 30N.

0048The elastic laminate should preferably have a softness according to Kawabata of at least 20, preferably at least 30 and most preferably at least 40.

0049It is further desired that it has a formability according to Kawabata of no more than 50, preferably no more than 30, more preferably no more than 20 and most preferably no more than 10.

0050It is also desired that the elastic laminate has a drapability according to Kawabata of no more than 40.

0000Description of Test Methods

0000Opacity

0051The opacity of the elastic web material is measured according to a slightly modified version of SS-ISO 2471:1998 by the Swedish Standard Institute (Diffuse Reflectance Method). The method is originally intended for measuring the opacity for paper sheets, but it also functions well for measuring the opacity of other types of sheet materials, such as elastic laminates according to this invention. The opacity is measured in an unstretched condition of the elastic web material. The principle of the test method is to measure the Single-Sheet Luminous Reflectance Factor, R₀, through a single sheet against a standardized black backing and the Intrinsic Luminous Reflectance Factor, R_∞, against a completely opaque white backing. The opacity (%) is calculated from the formula 100·R₀/R_∞.

0052The following modifications of the test method were made:

0053i) When measuring the Single-Sheet Luminous Reflectance Factor, R₀, a black velvet fabric was used as backing.

0054ii) When measuring the Intrinsic Luminous Reflectance Factor, R_∞, the measurement was made on one single sheet of the elastic laminate against a white tile as backing.

0055iii) The CIE illuminant D65 (10°) was used instead of the CIE illuminant C (2°).

0056The measured opacity values are mean values from five measurements.

0000Puncture Strength

0057Puncture strength is measured according to ASTM Designation D3763-02. From penetration impact-type tests, this method produces data of load versus displacement. The maximum load is calculated for each laminate.

0000Tensile Strength (Reference: ASTM D 882)

0058The method measures tensile strength and elongation of difference elastic materials. The tensile strength and elongation of a well-defined test piece is tested by means of a tensile tester.

0000Apparatus: Instron 4301

0000Tensile tester connected to a computer

0000Crosshead speed: 500 mm/min

0000Clamp distance: 50 mm

0059Sample preparation: Test samples are cut from the entire width of the material. The width of the sample shall be 25.4 mm and the length at least 50 mm longer than the clamp distance if possible. It is of importance that the edges of the sample are even and without break notches. The samples are conditioned for at least 4h in 50%RH±5% RH and 23° C.±2° C. before testing.

0060Procedure: The tensile tester is calibrated according to the apparatus instructions and set to zero. The sample is mounted and it is ensured that it is not obliquely or unevenly fastened. The material is prevented from slipping by using clamps covered with galloon or similar material. The tensile tester is started, and stopped after the material has broken (if not automatically controlled). Measurements resulting from premature failures (i.e. the sample breaks at the clamp, or is damaged during preparation) are ignored if possible.

0061The following results are expressed by the tensile tester/computer:

0000Maximum force, N/25.4 mm

0000Elongation at maximum force, %

0000Break force, N/25.4 mm

0000Elongation at break force, %

0000Knee point, N/%

0000Elasticity test

0062The method measures how an elastic material behaves at repeated load and unload cycles. The sample is stretched to a predetermined elongation and a cyclic movement between 0 and said predetermined elongation is performed. Desired load and unload forces are recorded. The permanent, i.e. remaining, elongation of the relaxed material is measured.

0063A tensile tester, Lloyd LRX, able to perform cyclic movements and equipped with a printer/plotter or software presentation is used. The sample is prepared by cutting it to a width of 25 mm and a length that is preferably 20 mm longer than the distance between the clamps in the tensile tester.

0064The tensile tester is calibrated according to the apparatus instructions. The parameters needed for the test (load and unload forces) are adjusted to: <tables id="TABLE-US-00001" num="1"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="OFFSET" colwidth="35PT" align="left" /><colspec colname="1" colwidth="63PT" align="left" /><colspec colname="2" colwidth="56PT" align="right" /><colspec colname="3" colwidth="63PT" align="left" /><thead><row><entry /><entry /></row><row><entry /><entry namest="OFFSET" nameend="3" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>Crosshead speed:</entry><entry>500</entry><entry>mm/min</entry></row><row><entry /><entry>Clamp distance:</entry><entry>50</entry><entry>mm</entry></row><row><entry /><entry>Preload:</entry><entry>0.05</entry><entry>N</entry></row><row><entry /><entry namest="OFFSET" nameend="3" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0065The sample is placed in the clamps according to the marks and it is made sure that the sample is centred and fastened perpendicularly in the clamps. The tensile tester is started and three cycles between 0 and the predetermined elongation, equal to the highest defined 1 st load, are performed. Before the last cycle, the sample is relaxed for 1 minute, then the permanent elongation is measured by stretching the sample until a force of 0.1 N is detected and the elongation is read.

0066The permanent elongation after relaxation should be less than 10% and is measured by the method above. Thus an elasticity of 30% is defined as that the laminate should have a permanent relaxation after elongation of less than 10% after being exerted to an elongation of 30% in the tensile tester above. An elongation of 30% means an elongation to a length that is 30% longer than the initial length of the sample.

0000Kawabata Tests

0067The Kawabata KES-FB test is a Japanese quality judgment system for used for textile materials and is disclosed in “The Standardization and Analysis of Hand Evaluation (2nd Edition), Sueo Kawabata, July 1980, The Hand Evaluation and Standardization Committee, The Textile Machinery Society of Japan”. The test used in this invention uses two of the Kawabata testing machines, KES-FB2 for measuring Bending rigidity, B (gf·cm²/cm), and KES-FB1 for measuring Shear stiffness, G (gf/cm·degree) and Tensile strain, EMT (%).

0000Bending Rigidity (B) KES-FB2

0068The slope was measured between <b>0</b>.<b>5</b> cm-1 and 1.5 cm-1 and −0.5 cm-1 and −1.5 cm-1.

0069The measurements were performed in both directions (MD and CD) with the following settings:

0000Total sample area: 20×20 cm;

0000Maximum curvature: Kmax=±2.5 cm-1;

0000Bending rate: 0.5 cm-¹/sec;

0000Sample effective dimension: 20 cm length and 1 cm width;

0000Bending deformation is applied to the width direction.

0000Shear stiffness (G) KES-FB1

0070The slope was measured between 0.5 cm⁻¹and 2.5 cm⁻¹and 0.5 cm⁻¹and −2.5 ^cm-1.

0071The measurements were performed in both directions (MD and CD) with the following settings:

0000Total sample area: 20×20 cm;

0000Tension of specimen: W=W=10 gf/cm;

0000Maximum shear angle: (φ=±8.

0000Sample effective dimension: 20 cm width and 5 cm length;

0000Shear deformation is applied to the width direction.

0000Tensile strain (EMT)

0072The measurements were performed in both directions (MD and CD) with the following settings:

0000Total sample area: 20×20 cm;

0000Maximum load: Fm=500 gf/cm;

0000Tensile speed: 0.2 mm/sec.

0000Sample effective dimension: 20 cm width and 2.5 cm length;

0000Tensile deformation is applied to the length direction.

0000Elongation sens 50 mm/10V.

0000Softness (S)

0073The Softness (S) according to Kawabata is obtained from the formula: <br /><i>S</i>=√{square root over (EMT/B)}<br /> Formability (F)

0074The Formability (F) according to Kawabata is obtained from the formula: <br /><i>F=B</i>·EMT. <br /> Drapability (D)

0075The Drapability (D) according to Kawabata is obtained from the formula: <br /><i>D=</i>116+25·log(B·G/W), wherein W is the basis weight of the sample.

EXAMPLES

0000Opacity

0076The opacity of an elastic laminate sample was measured. The sample was an elastic laminate according to the invention comprising an inner apertured three-layer elastic film of PE-SEBS-PE, basis weight 36 g/m²and two outer layers of spunbond material, PP (polypropylene), each having a basis weight of 22 g/m². The laminate is produced by a modified version of the method disclosed in WO 03/04788 and which is described above, wherein one spunbond layer is applied to the film in a tacky state and will thus bond to the film layer, while the other spunbond layer is adhesively laminated to the film layer using for example a pressure sensitive hot melt adhesive (glue amount 3 g/m²). The laminate is incrementally stretched, at which the non-elastic spunbond layers are stretched to a point below the elongation at maximum load to retain some strength in the spunbond layers. The elasticity of the laminate after stretching is close to the elasticity of the elastic film layer.

0077The above-mentioned basis weights of the layers refer to the finished laminate after stretching. Before stretching the basis weight of the individual layers were: inner film layer 40 g/m², outer spunbond layers 25 g/m²each and glue layer 3 g/m². Since it is difficult to measure the basis weights of the individual layers after lamination and stretching an approximation has been made from the basis weights of the layers before lamination and stretching. The laminate before stretching had a total basis weight before stretching of 93 g/m²and after stretching it had a basis weight of 85 g/m², which means a deformation of about 10%. It is then assumed that the deformation of the individual fibrous layers and the film layer is the same, i.e. about 10%.

0078The inner film layer contained 4.9% by weight filler in the form of TiO2. The open area of the film layer was 13%.

0000The opacity of the laminate was about 68%.

0079An opacity value of at least 40% is acceptable in order to provide the desired cloth-like appearance of the pant diaper disclosed above, which in considerable areas of the chassis contains the elastic laminate as the sole component. Preferably the opacity should be at least 50%, more preferably at least 60%.

0080It is further desired, for example for cost reasons, to have a low basis weight of the elastic laminate. The basis weight should be 100 g/m²or lower. The ratio Opacity/Basis Weight is therefore also an aspect of this invention. Preferably this ratio should be at least 0.4, more preferably at least 0.5 and most preferably at least 0.6, wherein opacity is measured in % and the basis weight is measured in g/m².

0000Puncture Resistance

0081The puncture resistance of three different samples (A, B and C) were measured according to ASTM Designation D3763-0²and are shown in Table 1.

0000Tensile Strength

0082The puncture resistance of three different samples (A, B and C) were measured according to the method given above and are shown in Table 1.

0000Elasticity

0083The elasticity of three different samples (A, B and C) were measured according to the method given above and are shown in Table 1. Sample A is an elastic laminate according to WO03/047488 with 15 gsm PP spunbond nonwoven on both sides of a 40 gsm elastic film. The used spunbond nonwoven has an elongation at maximum load of 60%, which is less than the elasticity of the laminate. The low puncture resistance of this material means that it falls outside the scope of the present invention.

0084Sample B is an elastic laminate with 25 gsm PP/PE spunbond nonwoven on both sides of a 36 gsm elastic film.

0085Sample C is an elastic laminate with one layer of 25 gsm PP/PE nonwoven and one layer of 20gsm PP/PE nonwoven on opposite sides of a 36 gsm elastic film. <tables id="TABLE-US-00002" num="2"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="OFFSET" colwidth="133PT" align="left" /><colspec colname="1" colwidth="28PT" align="center" /><colspec colname="2" colwidth="28PT" align="center" /><colspec colname="3" colwidth="28PT" align="center" /><thead><row><entry /><entry namest="OFFSET" nameend="3" align="center">TABLE 1</entry></row><row><entry /><entry /></row><row><entry /><entry namest="OFFSET" nameend="3" align="center" rowsep="1" /></row><row><entry /><entry>Sample</entry><entry>Sample</entry><entry>Sample</entry></row><row><entry /><entry>A</entry><entry>B</entry><entry>C</entry></row><row><entry /><entry namest="OFFSET" nameend="3" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="1" colwidth="133PT" align="left" /><colspec colname="2" colwidth="28PT" align="char" char="." /><colspec colname="3" colwidth="28PT" align="char" char="." /><colspec colname="4" colwidth="28PT" align="char" char="." /><tbody valign="top"><row><entry>Puncture force (N)</entry><entry>12.8</entry><entry>49.5</entry><entry>40.6</entry></row><row><entry>Basis weight (gsm)</entry><entry>78.66</entry><entry>87.96</entry><entry>82.71</entry></row><row><entry>Tensile strength and Elongation</entry></row><row><entry>MD (machine direction)</entry></row><row><entry>Tensile strength at Peak (MD), N/25 mm</entry><entry>8.29</entry><entry>25.3</entry><entry>28.03</entry></row><row><entry>Elongation at break, %</entry><entry>269.82</entry><entry>311.94</entry><entry>691.47</entry></row><row><entry>Elongation at Peak/Deformation, %</entry><entry>136</entry><entry>111.44</entry><entry>109.28</entry></row><row><entry>CD (cross direction)</entry></row><row><entry>Tensile strength at Peak (CD), N/25 mm</entry><entry>11.72</entry><entry>11.15</entry><entry>9.16</entry></row><row><entry>Elongation at break, %</entry><entry>792.87</entry><entry>768.19</entry><entry>160.15</entry></row><row><entry>Elongation at Peak/Deformation, %</entry><entry>74.88</entry><entry>124.82</entry><entry>134.42</entry></row><row><entry>Determination of load & unload forces</entry></row><row><entry>and permanent elongation</entry></row><row><entry>Tensile strength at 80% elongation (1st</entry><entry>2.78</entry><entry>7.11</entry><entry>10.66</entry></row><row><entry>cycle)</entry></row><row><entry>Permanent Elongation (3rd cycle)</entry><entry>7.86</entry><entry>7.52</entry><entry>8.09</entry></row><row><entry>3rd Retraction Forces</entry></row><row><entry>At 80%, N/25 mm</entry><entry>1.14</entry><entry>1.44</entry><entry>1.42</entry></row><row><entry>At 60%, N/25 mm</entry><entry>0.82</entry><entry>0.85</entry><entry>0.8</entry></row><row><entry>At 40%, N/25 mm</entry><entry>0.54</entry><entry>0.53</entry><entry>0.48</entry></row><row><entry namest="1" nameend="4" align="center" rowsep="1" /></row></tbody></tgroup></table></tables><br /> Kawabata Tests

0086Four different samples were measured in a Kawabata test with respect to Bending rigidity (B), Shear stiffness (G) and Tensile strain (EMT). From these measured values the Softness (S), Formability (F) and Drapability (D) were calculated.

0000The Four Samples Were:

0087Sample laminate (SL): an elastomeric laminate according to an embodiment of the invention comprising an inner apertured three-layer elastomeric film of PE-SEBS-PE, basis weight 36 g/m²and two outer layers of spunbond material, PP (polypropylene), each having a basis weight of 22 g/m². The laminate is produced by a modified version of the method disclosed in WO 03/04788 and which is described above, wherein one spunbond layer is applied to the film in a tacky state and will thus bond to the film layer, while the other spunbond layer is adhesively laminated to the film layer using for example a pressure sensitive hot melt adhesive (glue amount 3 g/m²). The laminate is incrementally stretched, at which the non-elastic spunbond layers are stretched to a point below the elongation at maximum load to retain some strength in the spunbond layers. The elasticity of the laminate after stretching is close to the elasticity of the elastomeric film layer.

0088The above-mentioned basis weights of the layers refer to the finished laminate after stretching. Before stretching the basis weight of the individual layers were: inner film layer 40 g/m², outer spunbond layers 25 g/m²each and glue layer 3 g/m². Since it is difficult to measure the basis weights of the individual layers after lamination and stretching an approximation has been made from the basis weights of the layers before lamination and stretching. The laminate before stretching had a total basis weight before stretching of 93 g/m²and after stretching it had a basis weight of 85 g/m², which means a deformation of about 10%. It is then assumed that the deformation of the individual fibrous layers and the film layer is the same, i.e. about 10%.

0089Ref. 1: Cotton-knitted goods, so called jersey with elastomeric threads.

0090Ref. 2: Outer coversheet of Tena Discreet incontinence pant (odour control, size medium) produced by SCA Hygiene Products AB. The outer coversheet comprises two layers of nonwoven with parallel elastic threads there between, which wrinkle the material.

0091Ref. 3: Outer coversheet material of Poïse normal super incontinence pant produced by Kimberly-Clark. The outer coversheet comprises two layers of nonwoven with parallel elastic threads there between which wrinkle the material.

0092A climate conditioning of the materials were performed at 20° C. and 65% RH for 48 hours. For the pant products, the absorbent core was removed and the outer coversheet was stretched over a knitwear measuring device for 24 hours and was then allowed to relax in the same climate during 24 hours.

0093The sizes of the samples were 10×10 cm.

0094All tests were made on three samples and in two material directions (machine direction, MD, and cross direction, CD).

0095The following results were obtained. <tables id="TABLE-US-00003" num="3"><table frame="none" colsep="0" rowsep="0" pgwide="1"><tgroup align="left" colsep="0" rowsep="0" cols="4"><colspec colname="OFFSET" colwidth="35PT" align="left" /><colspec colname="1" colwidth="70PT" align="center" /><colspec colname="2" colwidth="77PT" align="center" /><colspec colname="3" colwidth="77PT" align="center" /><thead><row><entry /><entry namest="OFFSET" nameend="3" align="center">TABLE 2</entry></row></thead><tbody valign="top"><row><entry /><entry /></row><row><entry /><entry namest="OFFSET" nameend="3" align="center" rowsep="1" /></row><row><entry /><entry>B, Bending rigidity</entry><entry>G, Shear stiffness</entry><entry /></row><row><entry /><entry>(gf · cm²/cm)</entry><entry>(gf/cm · degree)</entry><entry>EMT, Tensile strain (%)</entry></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="10"><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="21PT" align="center" /><colspec colname="3" colwidth="28PT" align="center" /><colspec colname="4" colwidth="21PT" align="center" /><colspec colname="5" colwidth="28PT" align="center" /><colspec colname="6" colwidth="21PT" align="center" /><colspec colname="7" colwidth="28PT" align="center" /><colspec colname="8" colwidth="35PT" align="center" /><colspec colname="9" colwidth="21PT" align="center" /><colspec colname="10" colwidth="21PT" align="center" /><tbody valign="top"><row><entry>Sample</entry><entry>MD</entry><entry>CD</entry><entry>Mean</entry><entry>MD</entry><entry>CD</entry><entry>Mean</entry><entry>MD</entry><entry>CD</entry><entry>Mean</entry></row><row><entry namest="1" nameend="10" align="center" rowsep="1" /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="10"><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="21PT" align="char" char="." /><colspec colname="3" colwidth="28PT" align="char" char="." /><colspec colname="4" colwidth="21PT" align="char" char="." /><colspec colname="5" colwidth="28PT" align="center" /><colspec colname="6" colwidth="21PT" align="center" /><colspec colname="7" colwidth="28PT" align="center" /><colspec colname="8" colwidth="35PT" align="char" char="." /><colspec colname="9" colwidth="21PT" align="char" char="." /><colspec colname="10" colwidth="21PT" align="center" /><tbody valign="top"><row><entry>SL</entry><entry>0.095</entry><entry>0.022</entry><entry>0.059</entry><entry>1.46</entry><entry>1.38</entry><entry>1.42</entry><entry>208.4</entry><entry>92.0</entry><entry>150.2</entry></row><row><entry>Ref. 1</entry><entry>0.03</entry><entry>0.03</entry><entry>0.03</entry><entry>0.58</entry><entry>0.64</entry><entry>0.61</entry><entry>160.6</entry><entry>173.2</entry><entry>166.9</entry></row><row><entry>Ref. 2</entry><entry>1.05</entry><entry>0.09</entry><entry>0.57</entry><entry>0.87</entry><entry>0.68</entry><entry>0.77</entry><entry>23.9</entry><entry>211.7</entry><entry>117.8</entry></row><row><entry>Ref. 3</entry><entry>1.53</entry><entry>0.04</entry><entry>0.78</entry><entry>1.74</entry><entry>1.21</entry><entry>1.47</entry><entry>26.28</entry><entry>195.3</entry><entry>110.8</entry></row><row><entry namest="1" nameend="10" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0096From these results the Softness (S), the Drapability (D) and the Formability (F) according to Kawabata were calculated according to the formulas stated above. These results are stated in Table 3 below. <tables id="TABLE-US-00004" num="4"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="42PT" align="center" /><colspec colname="3" colwidth="56PT" align="center" /><colspec colname="4" colwidth="42PT" align="center" /><colspec colname="5" colwidth="42PT" align="center" /><thead><row><entry namest="1" nameend="5" align="center">TABLE 3</entry></row><row><entry /></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row><row><entry /><entry /><entry>Drapability (D)</entry><entry>Formability</entry><entry>Basis</entry></row><row><entry /><entry>Softness (S)</entry><entry>116 + 25</entry><entry>(F)</entry><entry>Weight</entry></row><row><entry>Sample</entry><entry>{square root over (EMT/B)}</entry><entry>log(B · G/W)</entry><entry>B · EMT</entry><entry>(W) g/m²</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /></row></tbody></tgroup><tgroup align="left" colsep="0" rowsep="0" cols="5"><colspec colname="1" colwidth="35PT" align="left" /><colspec colname="2" colwidth="42PT" align="center" /><colspec colname="3" colwidth="56PT" align="center" /><colspec colname="4" colwidth="42PT" align="char" char="." /><colspec colname="5" colwidth="42PT" align="char" char="." /><tbody valign="top"><row><entry>SL</entry><entry>50</entry><entry>40</entry><entry>9</entry><entry>88</entry></row><row><entry>Ref. 1</entry><entry>75</entry><entry>13</entry><entry>5</entry><entry>231</entry></row><row><entry>Ref. 2</entry><entry>14</entry><entry>45</entry><entry>67</entry><entry>160</entry></row><row><entry>Ref. 3</entry><entry>12</entry><entry>51</entry><entry>87</entry><entry>133</entry></row><row><entry namest="1" nameend="5" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0097The results should be interpreted in the following way: <tables id="TABLE-US-00005" num="5"><table frame="none" colsep="0" rowsep="0"><tgroup align="left" colsep="0" rowsep="0" cols="3"><colspec colname="OFFSET" colwidth="14PT" align="left" /><colspec colname="1" colwidth="63PT" align="left" /><colspec colname="2" colwidth="140PT" align="left" /><thead><row><entry /><entry /></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row></thead><tbody valign="top"><row><entry /><entry>Softness (S):</entry><entry>a higher value indicates a softer material.</entry></row><row><entry /><entry>Drapability (D):</entry><entry>a higher value indicates a stiffer material.</entry></row><row><entry /><entry>Formability (F):</entry><entry>a higher value indicates that the material is</entry></row><row><entry /><entry /><entry>less formable.</entry></row><row><entry /><entry namest="OFFSET" nameend="2" align="center" rowsep="1" /></row></tbody></tgroup></table></tables>

0098The test laminate according to an embodiment of the invention has a Softness (S) and a Formability (F) according to Kawabata which is close to cotton-knitted goods (Ref. 1). Also the Drapability (D) according to Kawabata is closer to the cotton-knitted reference material than the other two tested materials. Thus the use of the elastomeric laminate provides a pant article having a cloth-like feeling close to a cotton material. The pant will also have an excellent comfort and fit to the wearer's body. By using the elastomeric laminate only in those parts of the pant in which the properties of the material is best utilized, a very economic utilization of the material is accomplished.

0099It is preferred that the laminate has a Softness (S) according to Kawabata of at least 20, more preferably at least 30 and most preferably at least 40. It is also preferred that the laminate has a Formability (F) according to Kawabata of no more than 50, preferably no more than 30, more preferably no more than 20 and most preferably no more than 10. It is also preferred that the laminate has a Drapability (D) according to Kawabata of no more than 40.

0100Although only preferred embodiments are specifically illustrated and described herein, it will be appreciated that many modifications and variations of the present invention are possible in light of the above teachings and within the purview of the appended claims without departing from the spirit and intended scope of the invention.