CO-EXTRUDED LAMINATE FILM AND METHOD FOR THE PRODUCTION OF A CO-EXTRUDED LAMINATE FILM

Abstract

A co-extruded laminate film has a first polymer material and a second polymer material, wherein the first polymer material extends over the full area and wherein the second polymer material is arranged only in certain sections, to form at least a first functional section with the second polymer material and at least a second functional section without the second polymer material. The ratio of a maximum film thickness (d.sub.max) determined in the first functional section to a minimum film thickness (d.sub.min) determined in the second functional section is at least 1.4:1. A method for producing the co-extruded laminate film extrudes the two polymer materials together to form first and second functional sections.

Claims

1. A co-extruded laminate film comprising a first polymer material and a second polymer material, wherein the first polymer material extends over a full area of the laminate film, and wherein the second polymer material is arranged only in certain sections of the laminate film, so that the laminate film has at least a first functional section with the second polymer material and at least a second functional section without the second polymer material, wherein a ratio of a maximum film thickness (d.sub.max) determined in the first functional section to a minimum film thickness (d.sub.min) determined in the second functional section is at least 1.4:1.

2. The co-extruded laminate film according to claim 1, wherein a ratio of a maximum total thickness (a.sub.2) of the first polymer material, determined in the second functional section, to a minimum total thickness (a.sub.1) of the first polymer material determined in the first functional section, is at least 2:1.

3. The co-extruded laminate film according to claim 1, wherein the second polymer material is elastic, and wherein the first functional section forms an elastic film section and the second functional section forms a non-elastic film section.

4. The co-extruded laminate film according to claim 1, further comprising a third polymer material, which is arranged in the at least one first functional section, between the first polymer material and the second polymer material.

5. The co-extruded laminate film according to claim 4, wherein the third polymer material extends over the full area or extends at least beyond the second polymer material.

6. The co-extruded laminate film according to claim 1, wherein the at least one first functional section runs is in form of a strip, running in a production direction (P).

7. The co-extruded laminate film according to claim 6, wherein the strip has a width between 1 cm and 12 cm perpendicular to the production direction (P).

8. The co-extruded laminate film according to claim 6, wherein at least two said first functional sections in the form of strips run in the production direction (P), wherein the distance between the strips is between 3 cm and 24 cm.

9. The co-extruded laminate film according to claim 1, wherein in the at least one first functional section, the second polymer material is covered on both sides by the first polymer material.

10. The co-extruded laminate film according to claim 9, wherein the laminate film has a layer structure that is symmetrical with reference to a center plane.

11. The co-extruded laminate film according to claim 4, wherein the at least one second functional section is formed, by at least 70 wt.-%, by the first polymer material and/or the third polymer material.

12. The co-extruded laminate film according to claim 1, wherein the first polymer material is formed by at least one polyolefin.

13. The co-extruded laminate film according to claim 12, wherein the first polymer material has an admixture of 3 wt.-% to 30 wt.-% polyolefin elastomer (TPO).

14. The co-extruded laminate film according to claim 1, wherein the second polymer material contains at least one styrene block copolymer and/or at least one polyolefin elastomer.

15. The co-extruded laminate film according to claim 1, wherein the maximum total thickness (d.sub.max) is between 25 m and 75 m and/or the minimum total thickness (d.sub.min) is between 15 m and 40 m.

16. The co-extruded laminate film according to claim 1, wherein a ratio of melt mass flow rates (MFR) at 200 C. and 5 kg of the first polymer material and of the second polymer material is 1:1 to 2:1.

17. A method for production of a co-extruded laminate film according to claim 1, comprising the steps of: guiding a melt of the first polymer material over the full area, and guiding a melt of the second polymer material only in certain regions, in the form of at least one strip, in an extrusion die, wherein the first polymer material and the second polymer material are extruded together, using the extrusion die, along a production direction (P), so that the co-extruded laminate film is formed with a thickness profile that varies along a transverse direction.

18. The method according to claim 17, wherein the extrusion die is configured as a cast die having an adjustable die lip, and the co-extruded laminate film is extruded as a flat film.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0110] Other objects and features of the invention will become apparent from the following detailed description considered in connection with the accompanying drawings. It is to be understood, however, that the drawings are designed as an illustration only and not as a definition of the limits of the invention.

[0111] In the drawings,

[0112] FIG. 1 shows a co-extruded laminate film,

[0113] FIG. 2 shows a co-extrusion adapter for the production of the co-extruded laminate film,

[0114] FIG. 3A shows a partial view of an extrusion die for the production of the co-extruded laminate film,

[0115] FIG. 3B shows a further partial view of the extrusion die for the production of the co-extruded laminate film,

[0116] FIG. 4 shows a top view of a co-extruded laminate film with a cutting pattern for forming cover layers for a disposable hygiene article,

[0117] FIG. 5 shows a cover layer formed from the co-extruded laminate film,

[0118] FIG. 6 shows an alternative embodiment of a co-extruded laminate film and a pre-product for a disposable hygiene article with the co-extruded laminate film,

[0119] FIG. 7 shows a further alternative embodiment of a co-extruded laminate film,

[0120] FIG. 8 shows a disposable hygiene article, and

[0121] FIG. 9 shows a force/stretching diagram.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0122] FIG. 1 shows a co-extruded laminate film having a first polymer material 1 and a second, elastic polymer material 2, wherein the first polymer material 1 extends over the full area and wherein the second, elastic polymer material 2 is provided only in certain sections. The second, elastic polymer material 2 extends in the form of strips along a production direction P, wherein elastic first functional sections 3 with the second polymer material 2 and, in the exemplary embodiment shown, preferably non-elastic second functional sections 4 without the second polymer material 2 are formed.

[0123] The ratio of a maximum film thickness d.sub.max determined in the first functional sections 3 to a minimum film thickness d.sub.min determined in the second functional sections 4 is then at least 1.4:1. The ratio of a maximum total thickness a.sub.2 of the first polymer material 1 determined in the second functional sections 4 to a minimum total thickness a.sub.1 of the first polymer material 1 determined in the first functional sections 3 is at least 2:1.

[0124] In this regard, it can be recognized that there is symmetry with reference to a center plane of the co-extruded laminate film, wherein a symmetrical three-layer structure occurs in the first functional sections 3. There the second, elastic polymer material 2 is covered, in each instance, with a layer having a thickness of a.sub.1/2 of the first polymer material 1.

[0125] The strips that run along the production direction P, i.e. corresponding to the first functional sections 3, have a width between 1 cm and 12 cm perpendicular to the production direction P. The distance between two first functional sections 3 and thereby the width of the second functional sections 4 is between 3 cm and 24 cm.

[0126] While a three-layer structure occurs in the first functional sections 3, in the exemplary embodiment shown, the second functional sections 4 are formed exclusively by the first polymer material 1.

[0127] The co-extruded laminate film can be produced in that a melt of the first polymer material 1 is supplied over the full area, and a melt of the second polymer material 2 is supplied merely in certain regions, in the form of strips, to an extrusion die 5 shown as an example in a partial view in FIG. 3A, for example in the form of a cast die having a co-extrusion adapter 6 (feed block) shown in FIG. 2. According to FIG. 2, the second polymer material 2 is supplied in the form of strips, in a center feed gap 7, while the first polymer material 1 is introduced through feed gaps 8a, 8b that lie on the outside, into a melt channel 9 within the co-extrusion adapter 6.

[0128] The first polymer material 1 is introduced by way of the feed gap 8a, 8b that lies on the outside.

[0129] In the extrusion die 5, the melt strand is widened to form the co-extruded laminate film. In order to achieve the thickness profile shown in FIG. 1, a die lip 10 can be provided on the extrusion die 5, as shown in FIG. 3B, which lip can be adjusted by means of a plurality of setting means 11.

[0130] In the exemplary embodiment shown as an example, the strips are already formed in the co-extrusion adapter 6. Alternatively, an extrusion die 5 having three coat-hanger manifolds can also be provided, for example, wherein the second polymer material 2 is supplied to the center coat-hanger manifold. The center coat-hanger manifold then has retaining elements for reducing the total melt stream of the second polymer material to the strips.

[0131] FIG. 4 shows a top view of the co-extruded laminate film with a plurality of elastic sections 3 and non-elastic sections 4. Furthermore, cutting lines 12 are included in the drawing, so as to form cover layers for a disposable hygiene article, in particular a diaper, from the co-extruded laminate film.

[0132] The cutting lines 12 are arranged in such a manner that each cover layer 2 has elastic sections 3 at its edges, which are removed in a center region, in each instance, by means of leg cutouts on the sides.

[0133] In this regard, the elastic sections 3 form elastic ears integrated into the waist regions of the cover layer that follow the center region in the longitudinal direction. To form a pull-up diaper, the sections can be connected to one another, for example bonded or glued. In order to form a diaper that can be put on using closure means, such closure means, for example hook-and-loop closures, can be placed on the integrated elastic ears.

[0134] To form the entire cover layer, the co-extruded laminate film can be laminated to at first one nonwoven, at least in certain regions.

[0135] In this regard, the placement of a nonwoven can take place over the full area, so that then the cover layer shown in FIG. 4 has at least one layer of nonwoven over the full area, on one side or also on both sides. Fundamentally, however, it is also possible to arrange nonwoven only partially on one side or on both sides, so as to cover specific functional regions, in particular functional regions that are of particular importance for the haptics, the appearance and/or the function of the cover layer.

[0136] The co-extruded laminate film can be pre-stretched, at least in certain regions. In the region of the non-elastic sections, pre-stretching can take place, for example, so as to achieve breathability. This is possible, for example, if the first polymer material is provided with fillers that form pores during stretching. In particular, it is thereby possible to configure the cover layer, as an outer layer of the diaper, to be both water-tight and breathable.

[0137] Pre-stretching in the first functional sections 3, also referred to as activation, can be practical in order to afterwards achieve easy stretchability during use of the diaper.

[0138] In the case of a disposable hygiene article, in particular in the form of a diaper, the cover layer can therefore be provided as a water-tight outer layer and be combined with a water-permeable inner layer. In this regard, an absorbent core is usually arranged between the water-permeable inner layer and the outer layer.

[0139] FIG. 5 shows, in a further embodiment, a cover layer that is cut from a co-extruded laminate film. In this regard, it is also indicated that the cutting lines 12 can run in such a manner that a strip of the first functional section 3 still remains on the lateral leg cutouts, wherein there then, too-if necessary after activation-certain elastic reset properties can be achieved, so as to achieve a better fit on the legs of a wearer.

[0140] FIG. 6, for a better understanding, shows an alternative embodiment of the co-extruded laminate film in one figure, on the one hand, and a pre-product formed with it, for a disposable hygiene article 13 having the co-extruded laminate film. The co-extruded laminate film, proceeding from the embodiment according to FIG. 1, has a third polymer material 14, which, like the first polymer material 1, extends over the full area. In the first functional sections 3, a structure having five layers is obtained. By means of the second polymer material 2, the first functional sections 3 have great elasticity. The third polymer material 14 also still has certain elastic properties, but a worse recovery capacity than the second polymer material. In this regard, the second functional sections 4 can still be elastic, in the sense of the invention, depending on their configuration. For a distinction from the first functional sections 3, the second functional sections 4 can also be referred to as semi-elastic.

[0141] The co-extruded laminate film according to FIG. 6 can be used to make regions having different elasticity available in the disposable hygiene article 13 in the form of a diaper. For this purpose, the co-extruded laminate film can be cut and arranged as shown, so that the first and second functional sections 3, 4, which run in the production direction in the co-extruded laminate film, run along transverse edges in the pre-product. Using the cutout of the co-extruded laminate film that is shown and cut through in its center, a front and a back waistband region 15 of the disposable hygiene article 13 can be formed, wherein a center section 16 having an absorbent core is formed by a separate material.

[0142] Because both the first polymer material 1 and the third polymer material 14 extend over the full area in the case of the co-extruded laminate film according to FIG. 6, a reverse assignment of terms is fundamentally also possible. In the assignment chosen, without restrictions, in the exemplary embodiment, the layers of the first polymer material 1 are comparatively thin, while with reference to the functional sections 3, 4, the change in thickness of the third polymer material is pronounced.

[0143] According to FIG. 1, the ratio of a maximum total thickness of the third polymer material 1, determined in the second functional sections 4, to a minimum total thickness of the first polymer material 1, determined in the first functional sections 3, is at least 2:1. Furthermore, the ratio of a maximum total thickness of a sum of the first polymer material 1 and of the third polymer material 14, determined in the second functional sections 4, to a minimum total thickness of a sum of the first polymer material 1 and of the third polymer material 14, determined in the first functional sections 3, is also at least 2:1.

[0144] The disposable hygiene article 13 is shown in FIG. 8, wherein the front and the back waistband region 15 are connected with one another.

[0145] FIG. 7 shows a further embodiment of the co-extruded laminate film having the first, second, and third polymer material 1, 2, 14. The third polymer material 14 is structured in the form of strips, but these are wider than the strips of the second polymer material. In this way it is possible, for example, to divide the second functional section 4 into a partial region 4a that is still elastic or, as described above, semi-elastic, and a non-elastic partial region 4b. The disposable hygiene article 13 shown in FIG. 8 can then have a continuous cutout of the co-extruded laminate film as an outer layer, wherein then the non-elastic partial region holds the absorbent core (see FIG. 6).

[0146] FIG. 9 shows, as an example, a force/stretching diagram for the first elastic functional section of the fifth exemplary embodiment according to Table 1, in the hysteresis measurement that has been described. The uppermost curve shows the behavior during the first stretching. The center curve shows the behavior during the second stretching. Essentially the same behavior occurs for the recovery of the material for both cycles, so that the corresponding lower curves lie on top of one another.

[0147] Although only a few embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention.