Stable Fiber Laminate, and Method and Device for the Production Thereof

Abstract

The invention relates to a fiber laminate comprising two supporting fleeces and an absorptive fiber material which is disposed between the two supporting fleeces and is strengthened by means of a hydroentanglement process. Also disclosed are a method and a device for producing such a fiber laminate. The inventive fiber laminate is provided with sufficient stability against delamination and great absorptive capacity. Zones with absorptive fiber material and zones in which the two supporting fleeces are in direct contact with each other are provided between the two supporting fleeces across the area of the fiber laminate such that zones are created in which the two supporting fleeces forming the outer layers are directly connected to each other

Description

The invention relates to a fiber laminate which comprises two carrier webs and absorptive fiber material inserted between the two carrier webs and is bonded by hydroentanglement. The invention further relates to a method and an apparatus for producing such a fiber laminate.

From EP 1 250 482 a method is known for the production of a composite nonwoven consisting of at least one carrier web, for example a spunbond web, and one layer of wood pulp deposited on such a carrier web for producing a hygiene product, wherein the spunbond web is consolidated in dry condition for preliminary bonding prior to coating with the super-absorbent material, the wood pulp layer is then added and both together are bonded by means of hydroentanglement and then are dried.

Furthermore EP 1 524 350 describes a fiber laminate, in particular an absorbent cleaning cloth, consisting of at least one pre-consolidated spunbond web made of filaments and at least one fiber layer made of hydrophilic fibers, wherein the fiber laminate is hydrodynamically consolidated and wherein embossed deformations are incorporated into the surface of the hydrodynamically consolidated fiber laminate. When producing such wiping and cleaning cloths, the two outer layers consisting of pre-consolidated spunbond webs and the inner layer consisting of air-laid pulp are bonded with each other by hydroentanglement.

Such products offer satisfactory properties with respect to costs and strength values, but in practical use their insufficient thickness and absorptive capacity are criticized. In addition, the delamination strength of the individual layers produced by the water jet treatment is not sufficient so that, especially in moist condition, the layers easily separate again. This disadvantage is partially remedied in the above-mentioned EP 1 524 350 by preliminary embossing of the web layers used or by subsequent embossing of the bonded end product.

It is the task of the present invention to describe a fiber laminate together with method and apparatus for producing the same which offers sufficient delamination stability and high absorptive capacity.

This task is solved by a fiber laminate in conformity with patent claim 1 and a corresponding method and a corresponding apparatus for producing such a fiber laminate.

The fiber laminate according to the invention comprises two carrier webs and absorptive fiber material inserted between these two carrier webs and is bonded by hydroentanglement. When looking at the surface area of this fiber laminate, there are sections with absorptive fiber material between the two carrier webs and sections where the two carrier webs directly touch each other.

In this way, sections are created where the two carrier webs forming the outside layers are directly connected with each other. This distinctly increases the delamination stability. This was demonstrated by trials in which the forces required for delamination were measured in dry and moist condition of the fiber laminate. The stability in moist condition of a fiber laminate according to the invention is very strongly increased compared to conventional fiber laminates. The absorptive fiber material is contained in individually separated square sections between the two carrier webs. The overall impression of the fiber laminate is that of a knobbed nonwoven with embeddings similar to a quilt.

In the process for production of such a fiber laminate absorptive fiber material is placed between two carrier webs. The three layers, namely the two carrier webs with the absorptive fiber material placed in between, are consolidated by means of hydroentanglement using a structuring perforated template with the openings in the template being of just such a size that the absorptive fiber material between the two carrier webs is washed away from the sides of the webs of the template toward the openings of the template by the water jet treatment. For this purpose, a corresponding device for production of the fiber laminate is provided with a structuring perforated template having openings with a diameter between 0.5 and 20 mm. Contrary to the known openings in a microporous shell, these openings are distinctly bigger because they are not designed for draining any liquid but for taking up the fibers of the absorptive fiber material between the two carrier webs which are washed away from the webs of the template. The width of the webs is preferably selected within a range from 1 to 5 mm.

The carrier webs either consist of spunbond webs or layers made of staple fibers which are preferably pre-bonded in dry condition, for example by calendering.

The absorptive fiber material favorably consists of a pulp layer, such as tissue, or a super-absorbent layer.

The areal weight of the carrier webs usually ranges from 3 to 18 g/cm2 and in particular from 6 to 10 g/cm2. The average areal weight of the absorptive fiber material preferably lies between 8 and 100 g/cm2 and in particular between 20 and 50 g/cm2.

The areas of absorptive material are preferably distributed over the surface of the fiber laminate in such a way that they provide the fiber laminate with a knobbed structure. It is also conceivable to use such structures of an arbitrary geometry in order to provide the fiber laminate with an attractive optical design as, for example, in the shape of a flower pattern formed by several structures.

The structuring template is favorably designed as drum shell or endless shell.

The invention will be exemplified below by reference to the drawing.

In a lateral cross-section through a fiber laminate above a section of a drum shell, water jets 10 meet the fiber laminate, which consists first of a carrier web 1 made of spunbond web at the top, absorptive fiber material 2 underneath and a second carrier web 3 also made of spunbond web at the bottom. In an area 12 seen over the surface of the fiber laminate, absorptive fiber material 2 is included between the top carrier web 1 and the bottom carrier web 3. In an area 13 top carrier web 1 and bottom carrier web 3 are in direct contact with each other. This structure is explained by the water jets 10 impinging from the top washing away the absorptive fiber material 2 from a web 7 of the template 4 toward the side in the direction of the openings 6 of the template 4. The impact of the water jets 10 thus literally forces the absorptive fiber material 2 away from the web 7 in the direction of the openings 6. Located underneath the structuring template 4 is a supporting wire mesh 5 with a supporting drum shell 11 underneath. The supporting wire mesh 5 can be generally designed as a porous boyd or also as a microporous shell. Shown beside the openings 6 of the template 4 is a distinctly smaller capillary opening 8, which is used for removal of water and for this purpose has a rather small diameter in a range of less than 0.45 mm.

REFERENCE LIST

1 first carrier web

2 absorptive fiber material

3 second carrier web

4 structuring template

5 supporting wire mesh

6 opening in the template

7 web between the openings of the template

8 capillary opening

10 water jets

11 supporting drum shell

12 area with absorptive fiber material

13 area where the two carrier webs come into direct

Claims

1. Fiber laminate which comprises two carrier webs (1, 3) and absorptive fiber material (2)

inserted between the two carrier webs (1, 3) and is bonded by hydroentanglement, characterized in that, seen over the surface of the fiber laminate, there are areas (12) with absorptive fiber material (2) between the two carrier webs (1, 3) and areas (13) where the two carrier webs (1, 3) come into direct contact.

2. Fiber laminate according to claim 1, characterized in that the carrier webs (1, 3) independently of each other are formed either as a layer of spunbond web or a staple fiber layer.

3. Fiber laminate according to claim 1 or 2, characterized in that the absorptive fiber material (2) consists of a pulp layer or a super-absorbent layer.

4. Fiber laminate according to one of the preceding claims, characterized in that the carrier webs (1, 3) are pre-bonded in dry condition.

5. Fiber laminate according to one of the preceding claims, characterized in that the areal weight of the carrier webs (1, 3) lies between 3 and 18 g/cm2, and in particular between 6 and 10 g/cm2.

6. Fiber laminate according to one of the preceding claims, characterized in that the average areal weight of the absorptive fiber material (2) lies between 8 and 100 g/cm2, and in particular between 20 and 50 g/cm2.

7. Fiber laminate according to one of the preceding claims, characterized in that the areas (12) with absorptive fiber material (2) between the two carrier webs (1, 3) provide the fiber laminate with a knobbed structure.

8. Method for production of a fiber laminate comprising two carrier webs (1, 3) and absorptive fiber material (2) inserted between the two carrier webs (1,3), wherein the fiber laminate is bonded by hydroentanglement over a structuring perforated template (4), characterized in that the absorptive fiber material (2) is washed away from the sides of the webs (7) by the water jet treatment in the direction of the openings (6) of the template (4).

9. Apparatus for production of a fiber laminate comprising two carrier webs (1, 3) and absorptive fiber material (2) inserted between the two carrier webs (1,3), including a device bonding the fiber material (2) by hydroentanglement, characterized in that the device comprises a structuring perforated template (4) with openings (6) having diameters between 0.5 and 20 mm.

10. Apparatus according to claim 9, characterized in that the perforated template (4) is designed as structuring drum shell.

11. Apparatus according to claim 9, characterized in that the perforated template (4) is designed as structuring endless belt.