Multilayer material and absorbent sanitary article comprising the same

Abstract

The invention describes a multilayer material comprising at least one first layer made of polymeric material having an upper face and a second layer made of closed cell foamed polymeric material having a lower face. The multilayer material comprises through holes which cross both the layers and occupy a surface of between 1 and 40% of the total surface of the upper face of said multilayer material. The multilayer material is advantageously used in an absorbent sanitary article in which the upper face of the first layer is positioned externally so that in use it is in contact with the user's skin and the lower face of the second layer is positioned towards the inside of the sanitary article in contact with other layers of polymeric material.

Claims

1. An absorbent sanitary article comprising a multilayer material, said multilayer material comprising at least one first layer made of polymeric material having an upper face and a second layer made of closed cell foamed polymeric material having a lower face, wherein said multilayer material comprises through holes which cross both the layers and occupy a surface of between 1 and 40% of a total surface of the upper face of said multilayer material, a mean area of each of said through holes calculated at a base of said through holes is between 0.05 and 0.5 cm′ and a number of said through holes is between 1 and 40 per cm′, said first layer made of polymeric material comprising a substance chosen from the group consisting of a non-woven fabric having a MD tensile strength of between 10 and 50 N/50 mm or a microperforated film with the through holes formed by microperforations and configured to, in use, face towards a user to provide an effect of softness and wherein said upper face of said first layer is positioned externally so that said upper face is configured to, in use, contact skin of the user and said lower face of said second layer is positioned towards an inside of said absorbent sanitary article in contact with other layers of polymeric material.

2. The absorbent sanitary article according to claim 1, characterised in that said through holes occupy a surface of between 5 and 30% of the total surface of the upper face of said multilayer material.

3. The absorbent sanitary article according to claim 1, characterised in that the number of said through holes is between 5 and 30 per cm.sup.2.

4. The absorbent sanitary article according to claim 1, characterised in that: the holes occupy a surface of between 1 and 10%, the mean area of the holes is between 0.1 and 1 cm.sup.2 and the number of holes per cm.sup.2 is between 5 and 25, or the holes occupy a surface of between 1′1 and 10%, the mean area of the holes is between 0.05 and 0.3 cm.sup.2 and the number of holes per cm.sup.2 is between 5 and 25, or the holes occupy a surface of between 10 and 20%, the mean area of the holes is between 0.1 and 1 cm.sup.2 and the number of holes per cm.sup.2 is between 5 and 25.

5. The absorbent sanitary article according to claim 1, characterised in that said second layer made of closed cell foamed polymeric material comprises a polyolefin.

6. The absorbent sanitary article according to claim 1, characterised in that said second layer made of closed cell foamed polymeric material is in polyethylene.

7. The absorbent sanitary article according to claim 1, characterised in that said second layer made of closed cell foamed polymeric material has a density of between 5 and 40 kg/m.sup.3.

8. The absorbent sanitary article according to claim 1, characterised in that said second layer made of closed cell foamed polymeric material has a thickness of between 0.2 and 3 mm.

9. The absorbent sanitary article according to claim 1, characterised in that said microperforated film comprises a number of holes between 300 per cm.sup.2 and 1000 per cm.sup.2.

10. Absorbent sanitary article comprising a multilayer material, said multilayer material comprising at least one first layer made of polymeric material having an upper face and a second layer made of closed cell foamed polymeric material having a lower face, wherein said multilayer material comprises through holes which cross both the layers and occupy a surface of between 1 and 40% of a total surface of the upper face of said multilayer material, a mean area of each of said holes calculated at a base of said through holes is between 0.05 and 0.5 cm.sup.2 and a number of said through holes is between 1 and 40 per cm.sup.2, said first layer made of polymeric material comprises a substance chosen from the group consisting of non-woven fabric or a microperforated film and wherein said upper face of said first layer is configured to be, in use, positioned externally so that said upper face is in contact with skin of a user and said lower face of said second layer is positioned towards an inside of said absorbent sanitary article in contact with other layers of polymeric material.

11. Multilayer material comprising at least one first layer made of polymeric material having an upper face and a second layer made of closed cell foamed polymeric material having a lower face, wherein said multilayer material comprises through holes which cross both the layers and occupy a surface of between 1 and 40% of a total surface of the upper face of said multilayer material, a mean area of each of said holes calculated at a base of said through holes is between 0.05 and 0.5 cm.sup.2 and a number of said through holes is between 1 and 40 per cm.sup.2, said first layer made of polymeric material comprises a substance chosen from the group consisting of non-woven fabric having a MD tensile strength of between 10 and 50 N/50 mm or a microperforated film with the through holes formed by the microperforations and configured, in use, face towards a user to provide an effect of softness.

Description

EXAMPLE 1

(1) A multilayer material is formed consisting of a first layer made of a non-woven fabric coupled with a second layer of closed cell foamed polyethylene.

(2) The first layer is a thermally bonded non-woven fabric with nominal weight of 13 g per square metre with the characteristics given in table 3:

(3) TABLE-US-00003 TABLE 3 Unit of Characteristics Test method measurement Batch mean Thickness WSP 120.6 mm 0.18 MD tensile strength WSP 110.4 N/50 mm 20.11 MD elongation WSP 110.4 % 16.05 CD tensile strength WSP 110.4 N/50 mm 3.21

(4) The second layer is a closed cell foamed polyethylene with thickness of 1 mm. In this case a known material such as Cell-Aire was used. Said material has an elongation at break of 8.5 mm, a punching test resistance of 5.5 N according to standard SAC-PL 012, longitudinal tensile strength of 10.9 N and transverse tensile strength of 4 N according to standard DIN 53571, longitudinal elongation at break of 19.9% and transverse elongation at break of 34% according to standard DIN53571.

(5) The laminate composed of the above two layers is perforated by needle technology with two perforation patterns with 11 points/cm.sup.2 and 18 points/cm.sup.2.

(6) The data relative to the perforation of the two laminates with 18 and 11 pins or points/cm.sup.2 are given in tables 4 and 5:

(7) TABLE-US-00004 TABLE 4 Percentage 18 area occupied Mean area No. Diameter of pins by holes of holes holes/cm.sup.2 holes mm mean 5.69 0.32 17.73 0.64

(8) TABLE-US-00005 TABLE 5 Percentage 11 area occupied Mean area Number of Diameter of pins by holes of holes holes/cm.sup.2 holes mm mean 7.29 0.72 10.13 0.96

(9) Since the perforation method does not ensure that there is always an exact quantity of holes in the unit of measurement, the mean must be obtained which is the result provided in the table. The number and dimensions of the holes in one cm.sup.2 can actually be double or half the mean.

(10) The first layer of non-woven fabric can be replaced by a microperforated film made of polyethylene formed of a microperforated material with 52 mesh in which the microperforations have been obtained by the vacuum method and using the same perforation pattern as shown in tables 4 and 5, for example having the characteristics given in table 6:

(11) TABLE-US-00006 TABLE 6 Unit of Characteristics Test method measurement Batch mean Base weight WSP 130.1 g/m.sup.2 10.35 Thickness WSP 120.6 Mm 0.30 MD tensile ASTM D882 N/inch 5.04 strength MD elongation ASTM D882 % 145.74 CD tensile ASTM D882 N/inch 2.13 strength CD elongation ASTM D882 % 415.07 Open Area PIN- % 13.97 OUT

EXAMPLE 2

(12) To form a multilayer material, the materials used both for the first and for the second layer are the same as those given in example 1, but the perforation pattern is different.

(13) In particular, to perform the perforation, in this case a “line” perforation pattern was used. In this case the multilayer material is obtained with a method according to which the material is perforated between two pressurised rollers on top of each other, the first roller having protrusions to perforate the material and the second roller rotating at a different speed from that of the first roller and with projecting parts with contact areas arranged to perforate the material together with the protrusions. The contact areas of the projecting parts are spaced by depressions to receive the processed material and have dimensions greater than the contact faces of the perforation projections. The perforation is made at the contact areas which leave an impression on the material. The contact areas are elongated and the length is at least four times the width so as to define a line or band. The line thus defined can be continuous or discontinuous in the machine direction. The main axis of the line can be either parallel or inclined with respect to the machine direction. The main axis of the line can follow a preferably periodic undulating path.

(14) The pointed tips of a cylinder engraved with a pattern of approximately 80 points act preferably on the smooth part of the cylinder with channels. This results in the formation of a line of holes, no more than two of which are in cross direction.

(15) Table 7 shows the characteristics of the holes for a line perforation example obtained with the method described above.

(16) TABLE-US-00007 TABLE 7 Percentage Line area occupied Mean area No. of Diameter of perforations by holes of holes holes/cm.sup.2 holes mm mean 3.56 0.17 20.69 0.47

EXAMPLE 3

(17) A multilayer material is formed comprising a first layer formed of a microperforated material with 52 mesh in which the microperforations have been obtained by the vacuum method and the characteristics of which can be found in table 3 of example 1 and a second layer comprising a closed cell foamed polyethylene, the characteristics of which are given in example 1.

(18) In this case the perforation pattern allows elliptical holes to be obtained in the direction of the sliding of the film during the hole formation phase.

(19) Table 8 shows the characteristics of the holes.

(20) TABLE-US-00008 TABLE 8 Percentage Undulating area occupied Mean area No. of Diameter of perforations by holes of holes holes/cm.sup.2 holes mm mean 14.24 0.65 21.85 0.91

(21) It should be noted that in this case the holes have an elliptical shape.

(22) It is important to note that both the line perforation pattern in table 7 and the undulating perforation pattern in table 8 are continuous patterns in which the development on a cylinder will be helical.