Fiber sheet structures with a wave-like three-dimensional structure

Abstract

Fibrous sheet structures with a wave-like three-dimensional structure, comprising a flat support layer into which a wave-shaped three-dimensional structure can be thermally shrunk, and a functional position wherein the functional layer and the support layer are joined to form a flat material, and wherein the flat material is formed into the wave-like three-dimensional structure by thermal release, characterized in that the functional layer comprises at least one, preferably two, meltblown nonwoven layers and the at least one, preferably two, meltblown nonwoven layers have a basis weight of 5 to 100 g / m² when the functional layer is provided 2 preferably 10 to 60 g / m² 2 , exhibits.

Description

[0001] The present invention relates to a fiber sheet structure with a wave-like three-dimensional structure according to the preamble of independent claim 1. The invention also relates to a fiber sheet structure with a wave-like three-dimensional structure according to claim 5.

[0002] A generic fiber surface structure comprises a flat carrier layer into which a wave-shaped three-dimensional structure can be thermally shrunk, and a functional layer, wherein the functional layer and the carrier layer are joined to form a flat product, and wherein the flat product is formed into the wave-shaped three-dimensional structure by thermal release.

[0003] Such a generic fiber sheet structure is known from EP 1 277 865 B1. Here, the functional layer is formed as a staple fiber nap, and the connection between the staple fiber nap and the carrier layer is achieved by welding using a calender. The welding is perpendicular to the direction of greatest shrinkage of the shrunken sheet structure and takes the form of regularly arranged lines. The wavy, three-dimensional structure of the fiber sheet structure increases the surface area of ​​the functional layer per unit area of ​​the fiber sheet structure, which can have a positive effect on the properties of the functional layer with regard to its function, such as its absorbency, as described in EP 1 277 865 B1.

[0004] However, such three-dimensional structures are also of interest for other functional areas, such as in the filter or acoustics sector, whereby it is crucial for the improved function that the functional area well adopts the wave-like three-dimensional structure generated by the support layer.

[0005] The task was therefore to provide an improved fiber surface structure with a wave-like three-dimensional structure, especially for further functions such as in the filter and / or acoustics area, whereby the functional position adopts the wave-like three-dimensional structure generated by the support layer in an improved manner.

[0006] The problem is solved by means of the features of claim 1. Accordingly, a solution to the problem according to the invention exists if the functional layer comprises at least one meltblown nonwoven layer and the at least one meltblown nonwoven layer has a basis weight of 5 to 100 g / m² when providing the functional layer. 2preferably 10 to 60 g / m² 2 , particularly preferably from 15 to 25 g / m³ 2 exhibits.

[0007] Surprisingly, it has been shown that such functional layers exhibit improved three-dimensional structure. This leads to an improvement in the function of the layer, particularly in filtering or acoustic applications. For example, the separation efficiency can be optimized, the energy efficiency class of the filter medium and / or the acoustic properties improved.

[0008] Advantageous embodiments of the present invention are the subject of the dependent claims.

[0009] According to a preferred embodiment, at least one meltblown nonwoven layer is made of a thermoplastic polymer, preferably PP, PBT and / or PLA.

[0010] Preferably, the at least one meltblown nonwoven layer has a thickness of 0.05 N / cm² under load. 2from 0.1 to 3 mm, preferably from 0.2 to 1 mm. This allows the meltblown nonwoven layer to better absorb the three-dimensional structure.

[0011] According to a preferred embodiment of the method, the functional layer comprises two meltblown nonwoven layers. The use of two meltblown nonwoven layers can increase the functionality of the layer, such as the separation efficiency when the fiber sheet is used as a filter medium.

[0012] According to a further embodiment, the functional layer comprises at least one support and / or cover layer. Such support and / or cover layers can be designed as spunbond nonwovens, staple fiber nonwovens, and / or grids. The corresponding support and / or cover layers can provide additional mechanical stability or protect the subsequent layer(s) of the functional layer from mechanical stresses. Preferably, the at least one support and / or cover layer has a basis weight of 5 to 30 g / m². 2 on.

[0013] According to a particularly preferred embodiment, the functional layer consists of a support and / or cover layer on two meltblown nonwoven layers. Such a functional layer readily conforms to the wave-like three-dimensional structure, ensuring good functionality.

[0014] According to another particularly preferred embodiment, the functional layer consists of at least one, preferably two, meltblown nonwoven layers between two support and / or cover layers.

[0015] In another preferred embodiment, the functional layer has a total basis weight between 10 and 150 g / m². 2 , preferably between 20 and 60 g / m² 2 , wherein the functional position preferably has a total thickness at a load of 0.05 N / cm 2 between 0.3 and 3.5 mm, preferably between 0.4 and 1.5 mm.

[0016] In a preferred embodiment, the functional layer is joined to the support layer by means of a calender, ultrasound, or adhesive bond. The functional layer is thus fixed to the support layer and deforms with it. Preferably, the connection is made at specific points. The connection points can be distributed regularly or irregularly across the surface. This point-based connection allows for the most unimpeded possible release of the support layer and simultaneously enables the functional layer to assume the wave-like, three-dimensional structure.

[0017] In a particularly preferred embodiment, the bonding is achieved using a calender, wherein the calender comprises a smooth roller and a textured roller, between which the functional layer and the support layer are guided. The calender facilitates efficient bonding of the functional layer and the support layer. Preferably, the functional layer faces the textured roller and the support layer faces the smooth roller, with the textured roller preferably being set to a temperature range of 110 to 140°C and the smooth roller to a temperature range of 70 to 110°C. This improves the bond between the functional layer and the support layer without prematurely dissolving the support layer. Preferably, the textured roller is designed such that point bonds are formed between the functional layer and the support layer.Preferably, the calender has a compression area of ​​0.8 to 10%, or even more preferably 4 to 6%, in order to achieve a balanced ratio between layer adhesion and air permeability.

[0018] The invention also provides a fibrous surface structure with a wave-like three-dimensional structure, preferably according to one of the embodiments described above, comprising: a carrier layer designed as a warp-knitted fabric comprising shrink threads, each incorporated into the warp-knitted fabric with bound-in sections and floating sections, wherein the shrink threads are arranged in a wave direction of the wave-like three-dimensional structure in the warp-knitted fabric, and a functional layer comprising at least one meltblown nonwoven layer, wherein the functional layer and the support layer are joined to form a flat material, and wherein the flat material is formed into the three-dimensional structure by thermal release.

[0019] A bound section is a section in which the respective shrink thread is interwoven with other components of the warp-knitted fabric. A floating section is a section between two bound sections in which the respective shrink thread is not bound into other interwoven components of the warp-knitted fabric, but runs parallel to them. The wave-like, three-dimensional structure is caused by the shrinkage of the bound sections and the floating sections of the shrink threads. This type of support layer can generate the wave-like, three-dimensional structure very precisely and robustly, ensuring that the functional layer also adopts this wave-like, three-dimensional structure.

[0020] In a preferred embodiment, the ratio of the length in the wave direction of one of the floating sections to the length in the wave direction of an adjacent, embedded section is in the range of 2:1 to 1:5, more preferably in the range of 1:1 to 1:3, further preferably in the range of 1:1.2 to 1:1.4, and most preferably in the range of 1:1.33, before the functional layer is connected to the support layer. The lengths in the wave direction, and thus the ratio, are measured with the support layer in a loose position. Preferably, the length in the wave direction of the floating sections is constant. This ratio results in a suitable wave shape. Preferably, the length in the wave direction of the floating sections is in the range of 0.5 to 4 cm, more preferably in the range of 1 to 2 cm, and most preferably in the range of 1.5 cm, before the functional layer is connected to the support layer.The length in the wave direction of the floating sections is measured with the support lying loosely.

[0021] In one embodiment, the carrier layer has a mesh density of 2 to 10 meshes / cm in the wave direction, preferably 4 to 6 meshes / cm in the wave direction, and more preferably 5.48 meshes / cm in the wave direction, before the functional layer is bonded to the carrier layer. These values ​​are specified for a tensioned state of the warp-knitted fabric in a knitting machine used to knit the carrier layer. The provided carrier layer thus has a good balance between stability and deformation during release. Preferably, the bonded sections extend over 8 to 30 meshes, more preferably over 13 to 20 meshes, and particularly preferably over 16 meshes, and / or the floating sections over 4 to 15 meshes, more preferably over 5 to 10, and particularly preferably over 8 meshes.These values ​​are also given for a tensioned state of the warp-knitted fabric in the knitting machine used to knit the carrier layer. This carrier layer ensures a suitable wave shape.

[0022] According to a particularly preferred embodiment, the shrink threads have a shrinkage factor such that the shrinkage factor of the carrier layer between the flat fabric and the fiber sheet structure with a wave-like three-dimensional structure is at least 2:1, wherein the shrinkage factor of the shrink threads outside the warp-knitted fabric is preferably at least 5:1, and more preferably at least 9:1. This also ensures a suitable wave shape.

[0023] In a preferred embodiment, the shrink threads are designed as monofilament yarn, made of LLDPE, cross-linked with gamma rays and / or have a diameter between 0.25 mm and 0.4 mm, preferably between 0.25 mm and 0.35 mm, more preferably 0.27 mm.

[0024] In a preferred embodiment, the warp-knitted fabric comprises, in addition to the shrink threads, filament yarns that are interlaced together, wherein the filament yarns preferably consist of polypropylene and / or comprise filaments with a fineness of 50 dtex to 250 dtex, preferably 167 dtex. The resulting carrier layer is particularly suitable for bonding with the functional layer and forming the wave-like three-dimensional structure.

[0025] Preferably, the warp-knitted fabric is knitted using a knitting machine having at least four guide bars, wherein a first guide bar produces a fringe layer from filament yarn, a second guide bar produces a fringe layer and stand-up thread layer from the shrink threads, and a third and fourth guide bar produce weft layers from filament yarn. This allows the carrier layer to be provided efficiently and the embedded and floating sections of the shrink threads to be formed.

[0026] Preferably, the warp-knitted fabric is knitted with a knitting machine that has a machine fineness in the range of E6 to E36, preferably E18.

[0027] Preferably, the warp-knitted fabric is knitted using a knitting machine that produces warp-knitted fabric with a basis weight of 50 to 200g / m². 2 , preferably from 80 to 150g / m² 2 , preferably from 90 to 110g / m² 2, provides. The provided support layer thus has a good balance between stability and deformation during triggering.

[0028] In a preferred embodiment, the release is achieved by applying heat, thereby allowing the material to shrink without stress. This results in an advantageous degree of shrinkage of the fiber sheet structure. Particularly preferably, the energy input is achieved by two heaters: a top heater and a bottom heater. This allows for efficient thermal release. Preferably, the heater facing the functional layer is set to a temperature range of 70 to 110°C, more preferably 80 to 95°C, and the heater facing the support layer to a temperature range of 110 to 160°C, more preferably 120 to 135°C. This releases the support layer without damaging the functional layer. Even more preferably, the top heater is assigned to the functional layer and the bottom heater to the support layer. This also facilitates the release of the support layer without damaging the functional layer.

[0029] Preferably, no pressure was applied to the flat material during the thermal triggering process.

[0030] Further preferably, the flat material passes through a heating area with a length of 1.5 to 5 m, preferably 2 m, and / or with a throughput speed of 2 to 20 m / min, preferably 4 m / min, during the thermal triggering.

[0031] Preferably, the flat goods had a residence time in the heating area of ​​0.4 to 1.5 minutes.

[0032] According to a further preferred embodiment, the fiber surface structure comprises a spunbond nonwoven covering on the wave-shaped three-dimensional structure, preferably on the functional layer, which has been applied after thermal triggering.

[0033] According to a preferred embodiment, the fiber sheet structure has an areal weight of 120 - 700 g / m². 2 , preferably 250 - 350 g / m² 2 , on.

[0034] In another preferred embodiment, the fiber sheet structure has a thickness measured by means of a nonwoven probe of 5 to 30 mm, preferably of 10 to 15 mm.

[0035] According to another preferred embodiment, the fiber sheet structure has an air permeability of 200 - 2000 l / m². 2 / s at 200 Pa.

[0036] In preferred embodiments, the fiber sheet structure is designed as a filter medium.

[0037] In preferred embodiments, the fiber surface structure is designed as an acoustic element.

[0038] One embodiment of the present invention will be explained in more detail below with reference to the drawings.

[0039] The figures show: Fig. 1 a schematic production line for the manufacture of an embodiment of a fiber sheet structure according to the invention, Fig. 2 a schematic top view of a bottom side of a support layer after connecting the functional layer and the support layer and before the release of the support layer, Fig. 3 A schematic side view of a functional position and support position before connecting the functional position to the support position and before triggering the support position, Fig. 4 a schematic top view of a top surface of the functional layer after connecting the functional layer to the support layer and before triggering the support layer, and Fig. 5 a schematic side view of the embodiment of the fiber surface structure according to the invention after the release of the support position.

[0040] In the following explanations, identical parts are designated by the same reference numerals. If a figure contains reference numerals that are not further explained in the corresponding figure description, reference is made to preceding or subsequent figure descriptions.

[0041] Fig. Figure 1 shows a schematic production line for an embodiment of a method for producing an embodiment of a fiber surface structure according to the invention.

[0042] In step a., a support layer 7 is provided by placing it under the functional layer 2 from step b. using a second unwinding station 8. The support layer 7 is flat when provided and thermally shrinkable into a wavy, three-dimensional structure. Furthermore, the support layer 7 is designed as a warp-knitted fabric comprising shrink threads 9 and filament yarn. The shrink threads 9 are incorporated into the warp-knitted fabric with bound-in sections 10 and floating sections 11, and the shrink threads 9 are arranged in a wave direction 12 of the wavy, three-dimensional structure yet to be formed in the warp-knitted fabric. Such a support layer is shown schematically from its underside in Fig. Figure 2 shows the meshes between the filament yarns and the shrink threads 9 only schematically, and the shrink threads 9 are shown separately from the filament yarns only in the floating sections 11. For the shrink threads 9, floating sections 11 and bound sections 10 alternate in the wave direction 12, with a ratio of the length in the wave direction 12 of the floating sections 11 to the length in the wave direction 12 of a respective adjacent bound section 10 being 1:1.33 – before thermal release. The shrink threads 9 according to this embodiment are designed as monofilament yarn, made of LLDPE, cross-linked with gamma rays before knitting, have a diameter of 0.27 mm, and have a shrink ratio outside the warp-knitted fabric of 10:1 with respect to both before and after thermal release.The filament yarns according to the embodiment consist of polypropylene and comprise filaments with a fineness of 167 / 1 dtex. According to the embodiment, the carrier layer 7 is knitted by means of a warp knitting machine having four laying bars, wherein a first laying bar produces a fringe lay from the filament yarn, a second laying bar produces a fringe lay and stand-up yarn lay from the shrink yarns 9, and a third and fourth laying bar produce weft lays from filament yarn having a machine fineness of E18 and which gives the warp-knitted fabric a basis weight of preferably 92 g / m². 2 provides.

[0043] In step b, a functional layer 2 is provided by placing a support and / or cover layer 4 onto an upper first meltblown nonwoven layer 5 and a lower second meltblown nonwoven layer 6 using three first unwinding stations 3. In the illustrated design, the first meltblown nonwoven layer 5 and the second meltblown nonwoven layer 6 are PP meltblown nonwoven layers with a basis weight of 10 g / m² each. 2 and a thickness at a load of 0.05 N / cm 2 of 0.2 mm each during preparation. The support and / or cover layer, as shown, is a spunbond nonwoven layer with a basis weight of 15 g / m². 2 and a thickness of 0.2 mm at a load of 0.05 N / cm 2 exhibits [issues].

[0044] Fig. Figure 3 shows a schematic side view of the functional layer 2 and the support layer 7 after the functional layer 2 has been placed on the support layer 7 and before any further process steps have been carried out. The schematic representation shows how the floating sections 11 of the shrink threads 9 run parallel to the interlaced components of the warp-knitted fabric and on the side of the support layer facing away from the functional layer 2.

[0045] Fig. Figure 1 shows a further step c. according to the embodiment of the process, in which the functional layer 2 is joined to the support layer 7 by means of a calender 13. This forms a flat product consisting of the functional layer 2 and the support layer 7. According to the embodiment, the calender 13 comprises a smooth roller 14 and a textured roller 15, between which the functional layer 2 and the support layer 7 are guided. The functional layer 2 faces the textured roller 15 and the support layer 7 faces the smooth roller 14, with the textured roller being set to a temperature of 130°C and the smooth roller to a temperature of 90°C. According to the embodiment, the textured roller is designed such that point connections are formed between the functional layer 2 and the support layer 2, and the calender 13 has a compression area of ​​6%. Fig. Figure 4 shows a schematic top view of the upper side of the functional layer 2 after connecting the functional layer 2 and the support layer 7 using the calender 13 and the point connection points 16.

[0046] In the next process step, the support layer 7, and thus the flat material, is thermally released to form the wave-like three-dimensional structure. For this purpose, the flat material is, as in Fig. The material is transferred to an oven 17, as shown in Figure 1. According to the embodiment, the oven 17 comprises a top heating element 18 and a bottom heating element 19, wherein the top heating element 18, facing the functional position 2, is set to a temperature of 90°C and the bottom heating element 19, facing the support position 7, is set to a temperature of 130°C. The oven 17, according to the embodiment shown, does not exert any pressure on the flat material, has a heating zone with a length of 2 m, and has a throughput speed of 4 m / min.

[0047] Upon thermal activation, the shrink threads 9 of the support layer 7 shrink in the embedded sections 10 and the floating sections 11, thereby forming the support layer 7 and thus the functional layer 2 into a wave-like three-dimensional structure. The support layer 7 and functional layer 2 in the wave-like three-dimensional structure constitute the exemplary embodiment of the fiber surface structure 1 according to the invention. Fig. Figure 5 shows a schematic side view of the embodiment of the fiber surface structure 1 according to the invention. QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 1 277 865 B1

[0003]

Claims

[1] Fibrous sheet structures with a wave-like three-dimensional structure, comprising a flat support layer into which a wave-shaped three-dimensional structure can be thermally shrunk, and a functional position wherein the functional layer and the support layer are joined to form a flat material, and wherein the flat material is formed into the wave-like three-dimensional structure by thermal release, characterized by that the functional layer comprises at least one, preferably two, meltblown nonwoven layers and that the at least one, preferably two, meltblown nonwoven layers have a basis weight of 5 to 100 g / m² when the functional layer is provided 2 preferably 10 to 60 g / m² 2 , exhibits. [2] Fiber sheet structure according to claim 1, characterized by that the functional layer comprises at least one support and / or cover layer, preferably with a basis weight of 5 to 30g / m² 2has, wherein the functional layer preferably consists of one of these support and / or cover layers on two meltblown nonwoven layers. [3] Fiber sheet structures according to claim 1 or 2, characterized by that the functional position and the support position are connected to each other by means of calendering, ultrasound or bonding, the connection preferably being point-by-point. [4] Fiber sheet structure according to claim 3, characterized by that the connection is made by means of a calender, wherein the calender comprises a smooth roller and a structured roller, between which the functional layer and the support layer have been guided, wherein the structured roller is preferably designed in such a way that point connections are formed between the functional layer and the support layer, wherein the calender further preferably has a compression area of ​​0.8 to 10%, more preferably of 4 to 6%. [5] Fiber sheet structures with a wave-like three-dimensional structure, preferably according to one of claims 1 to 4, comprising: a carrier layer designed as a warp-knitted fabric comprising shrink threads, each incorporated into the warp-knitted fabric with bound-in sections and floating sections, wherein the shrink threads are arranged in a wave direction of the wave-like three-dimensional structure in the warp-knitted fabric, and a functional layer comprising at least one meltblown nonwoven layer, wherein the functional layer and the support layer are joined to form a flat material, and wherein the flat material is formed into the wave-shaped three-dimensional structure by thermal release. [6] Fiber sheet structure according to claim 5, characterized by, that in the initial state of the support position, the ratio of a length in the wave direction of one of the floating sections to a length in the wave direction of an adjacent embedded section is in the range of 2:1 to 1:5, preferably in the range of 1:1 to 1:3, further preferably in the range of 1:1.2 to 1:1.4, particularly preferably in the range of 1:1.33, wherein the length in the wave direction of the floating sections is further preferably constant. [7] Fiber sheet structures according to one of claims 5 to 6, characterized by , that the shrink threads have such a shrinkage factor that a shrinkage factor of the carrier layer between the flat material and the fiber surface structure with a wavy three-dimensional structure is at least 2:1, wherein the shrinkage factor of the shrink threads outside the warp-knitted material is preferably at least 5:1, further preferably at least 9:

1. [8] Fiber sheet structures according to any one of claims 5 to 7, characterized by that the shrink threads are designed as monofilament yarn, are made of LLDPE, are cross-linked with gamma rays and / or have a diameter in the range of 0.25 mm to 0.4 mm, preferably in the range of 0.25 mm to 0.35 mm, more preferably of 0.27 mm. [9] Fiber sheet structures according to any one of claims 5 to 8, characterized by , that the warp-knitted fabric comprises, in addition to the shrink threads, filament yarns which are interlaced together, wherein the filament yarns preferably consist of polypropylene and / or comprise filaments with a fineness of 50 / 1 dtex to 250 / 1 dtex. [10] Fiber sheet structure according to claim 9, characterized by, that the carrier layer is knitted with a knitting machine which has at least four laying bars, wherein a first laying bar produces a fringe layer from filament yarn, a second laying bar produces a fringe layer and stand-up yarn layer from the shrink yarns, and a third and fourth laying bar produce weft layers from filament yarn. [11] Fiber sheet structures according to claim 9 or 10, characterized by that the warp-knitted fabric is knitted with a knitting machine that has a machine fineness in the range of E6 to E36, preferably E18, and / or wherein the warp-knitted fabric has a basis weight of 50 to 200g / m² 2 , preferably from 80 to 150g / m² 2 , preferably from 90 to 110g / m² 2 , exhibits. [12] Fiber sheet structures according to any one of claims 5 to 11, characterized by, that the thermal triggering is carried out with two heaters, an upper heater and a lower heater, wherein preferably the heater facing the functional position is set to a temperature range of 70 to 110°C, more preferably 80 to 95°C, and the heater facing the support position is set to a temperature range of 110 to 160°C, more preferably 120 to 130°C, wherein further preferably the upper heater is assigned to the functional position and the lower heater to the support position. [13] Fiber sheet structure according to claim 12, characterized by , that no pressure was exerted on the flat material during the thermal activation, that the flat material passed through a heating area with a length of 1.5 to 5 m, preferably 2 m, and / or that the flat material passed through the heating area at a speed of 2 to 20 m / min, preferably 4 m / min. [14] Fiber sheet structures according to any one of claims 1 to 13, characterized by, that the fiber sheet structure has a basis weight of 120 to 700 g / m² 2 , preferably from 250 to 350 g / m² 2 , a thickness measured using a nonwoven sensor of 5 to 30 mm, preferably of 10 to 15 mm, and / or an air permeability of 200 to 2000 l / m 2 / s at 200 Pa.

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