Elastic strap part for diaper closure

Abstract

An elastic diaper part has an inelastic substrate layer having a wide inner end for connection to a diaper and a narrow and opposite outer end spaced in a stretch direction from the inner end, narrower than the inner end, and adapted for connection to a closure. An elastic film is juxtaposed and generally contiguous with the substrate layer, and there is an array of parallel adhesive strips extending transversely of the direction between the substrate layer and the elastic film. Each strip adheres the film to the substrate layer, and the strips are each of a respective strip width and separated by spaces each of a respective spacing width. The strip and/or spacing width varies from the inner end to the outer end such that the diaper part stretches uniformly between its inner and outer ends when stretched in the direction.

Claims

1. An elastic diaper part comprising: a substrate layer having an inner end of predetermined width adapted for connection to a diaper and an opposite outer end spaced in a direction of stretch from the inner end, of narrower width than the inner end, and adapted for connection to a closure, a width transverse to the direction of the substrate layer decreasing from the outer end to the inner end; an elastic film juxtaposed and generally contiguous with the substrate layer; and an array of parallel adhesive strips extending transversely of the direction, between the substrate layer and the elastic film, and each adhering the film to the substrate layer, the strips each being between the inner end and the outer end of a respective constant strip width of between 0.5 mm and 1.5 mm and separated by spaces each of a respective spacing width varying between the inner end and the outer end from 0.5 mm to 2.0 mm such that the diaper part stretches uniformly between its inner and outer ends when stretched in the direction and such that a portion covered by the adhesive strips increases toward the outer end.

2. The diaper part defined in claim 1, wherein the substrate layer is stretch-activated.

3. The diaper part defined in claim 2, wherein the substrate layer is a nonwoven.

4. The diaper part defined in claim 3, wherein there are two nonwoven substrate layers sandwiching the film and there are two arrays of adhesive strips each between a respective one of the substrate layers and a respective face of the film.

5. The diaper part defined in claim 4, wherein further comprising: means stiffening the substrate layer only immediately adjacent each of the ends.

6. The diaper part defined in claim 5, wherein the stiffening means is a stiff layer laminated between the substrate layers at least at the narrow outer end.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) The above and other objects, features, and advantages will become more readily apparent from the following description, reference being made to the accompanying drawing in which:

(2) FIG. 1 is a longitudinal section through an elastic diaper part in the stretching direction;

(3) FIG. 2 is a top view of the diaper part shown in FIG. 1;

(4) FIG. 3 shows the array of an adhesive bond between a substrate layer and an elastic film of the diaper part shown in FIGS. 1 and 2;

(5) FIG. 4 is a large-scale view of a detail from FIG. 3; and

(6) FIG. 5 is a view like FIG. 3 showing an alternative form of the invention.

SPECIFIC DESCRIPTION OF THE INVENTION

(7) As seen in FIGS. 1-4 an elastic diaper part in practice also referred to as a diaper ear is made of a laminate that has at least one substrate layer 1 and an elastic film 2 bonded to the substrate layer 1 and elastically stretchable in a stretch direction A at least in the region of the elastic film 2. According to a preferred embodiment of the invention, the elastic film 2 is laminated between two substrate layers 1 and is bonded thereto, each of the substrate layers 1 being made of a nonwoven web. The substrate layers 1 are not elastic but are stretchable to a limited degree.

(8) According to FIG. 2, the laminate has an inner end 3 for attachment to a diaper and an outer end 4 for a closure, for example a tape or a closure part provided with hooks of a hook/loop fastener. The ends 3 and 4 define inner and outer end edges 3 and 4. The outer end 4 has a narrower width B.sub.2 transverse to the stretch direction than the inner end 3 of width B.sub.1. Here, the diaper part has the shape of a quadrilateral, the end edges 3 and 4 running parallel to each other and the two long sides 5 and 5 being oriented skewed relative to each other. The diaper part thus is a right trapezoid. Furthermore, the long sides 5 and 5 can also be curved in the shape of a bow.

(9) The diaper part has inelastic zones a.sub.1 and a.sub.2 at the attachment ends 3 and 4. Between the inelastic zones a.sub.1 and a.sub.2, the diaper part has an elastic region c. In this elastic region c between the inner and outer ends 3 and 4, the elastic film 2 is bonded to the outer substrate layer 1 made of nonwoven material by a plurality of parallel adhesive strips 6. The adhesive strips 6 extend transverse to the stretch direction A.

(10) The array of the adhesive bonds between the elastic film 2 and the two outer substrate layers 1 is shown in FIGS. 3 and 4. The adhesive strips 6 form an array that has a smaller spacing s.sub.2 between adjacent adhesive strips 6 in a region c.sub.2 adjacent the outer end 4 than in a region c.sub.1 adjacent the inner end 3. The regions c.sub.1 and c.sub.2 each comprise at least two adhesive strips 6 having an adhesive-free intermediate space between the adhesive strips. In the embodiment shown in FIGS. 3 and 4, the adhesive strips 6 have a constant width b of, for example, 1.0 mm, the width b being specified in a value range between 0.5 mm and 1.5 mm. The spacing s between the adhesive strips 6 changes as a function of the width B of the laminate and, depending on the width of the laminate, has values specified between 0.5 mm and 2.0 mm.

(11) According to an embodiment shown in FIG. 5, the spacing s between the adhesive strips 6 is constant and the width of the adhesive strips 6 varies from a wide width b.sub.2 in a region c.sub.2 adjacent the narrow end to a narrow width b.sub.1 adjacent an inner region c.sub.1 at the inner end 4. In a region c.sub.2 adjacent the outer end 4, the adhesive strips 6 are wider than in the region c.sub.1 adjacent the inner end 3.

(12) The measures shown in FIGS. 3 to 5 can also be combined with one another. According to the invention, the portion of the adhesive area formed by the adhesive strips 6 and the base region, which comprises the adhesive region and the adhesive-free regions, changes depending on the width B of the laminate. Thus, the portion of the adhesive region relative to the base region increases as the width B of the laminate becomes smaller. Preferably, the width b of the adhesive strips 6 and/or the spacing s between adjacent adhesive strips 6 is set depending on the width B of the laminate in such a way that stretching of the elastic region c is essentially uniform when the laminate is stretched in the stretch direction. The distribution of adhesive according to the invention depends on the geometry of the diaper part, and results in uniformity of stretching of the diaper part so that when the diaper part is extended in the stretch direction, the elastic region c.sub.2 near the outer end 4 extends just as much as the elastic region c.sub.1 adjacent the inner end. This results in a better distribution of the performance of the diaper part.

(13) The elastic region c of the laminate is mechanically activated. For mechanical activation, the laminate runs through a profile roller arrangement and is locally overstretched, that is stretched beyond its elastic limit, in the roller gap between the profile rollers. The mechanical activation is visible on the finished product in the form of so-called activation strips. The activation strips extend parallel to the adhesive strips 6 and bring about an improvement of the extensibility of the material. The attachment ends 3 and 4 of the laminate are designed as inelastic zones a.sub.1 and a.sub.2 whose layer structure is different at the inner and outer ends 3 and 4. The inner end 3, which has a large width B.sub.1 and is attachable to a diaper, is soft and flexible and is made up of just the two substrate layers 1 made of nonwoven material that are bonded to each other. The elastic film 2 terminates before the inner end 3. In the inelastic zone a.sub.1, the layers 1 and 2 are surface-bonded to each other. The surface-bonded adhesive bond extends past the edge of the elastic film 2 into a region of the elastic film 2 close to the edge. The outer end, to which a closure in the form of, for example, a hook or barb tape is attachable, is stiffened by a reinforcement layer 7 that is anchored in an overlap area on the section of the diaper part provided with the laminated-in elastic film 2. The overlap area can be about 2 mm to 10 mm wide. The reinforcement layer 7 is made of a polymer that, compared to the mechanical properties of the elastic film 2, is distinguished by a greater bending stiffness and high tensile strength.