Method And Device For The Production Of A One-layered Or Multilayered Nonwoven Fabric

Abstract

The invention relates to a method for the production of a one-layered or multilayered nonwoven fabric, a machine for the production of such a nonwoven fabric, and a correspondingly produced nonwoven fabric. The task of improving such a method and a production apparatus underlies the invention to the effect that projecting loops and fibrils no longer stick out, and thus individual filaments can be prevented from pulling out during the use of the nonwoven fabric. According to the invention, this is achieved in that the nonwoven fabric is smoothed after water needling by the use of a calendar. The machine according to the invention is characterized by the fact that the machine has a spun bonded fabric, at least one subsequent needling device, a dryer connected thereto, and thereafter at least one calendar.

Description

[0001] The invention relates to a method for producing a one-layered or multilayered nonwoven fabric, as disclosed in the preamble to claim 1, as well as the apparatus for producing such a nonwoven fabric and also a correspondingly produced nonwoven fabric.

[0002] A nonwoven fabric composed of a plurality of yarn-type fiber groups is already known (EP 0 626 902 B1), wherein these groups are joined at connecting points through fibers belonging to a plurality of these groups to delimit a predetermined pattern of holes in the nonwoven fabric, wherein the nonwoven fabric has a transparency index of at least 0.5 and a computed fiber bundle density of at least 0.14 gram per cubic centimeter.

[0003] It is the object of the present invention to improve a production method and a production apparatus in accordance with the respective preamble. The goal advantageously is to prevent loops or fibrils from sticking out of the nonwoven fabric, thereby preventing the pulling out of individual filaments during the use of the nonwoven fabric.

[0004] This object is solved according to the invention by smoothing the nonwoven fabric with the aid of a calender, following the water needling process. The nonwoven fabric preferably is a spun-bonded fabric that is subjected to a hydrodynamic needling technique, is subsequently dried, and is then smoothed with the aid of a calender.

[0005] As a result, the loops or fibrils that stick out and are extremely bothersome when using a one-layer or also a multilayer nonwoven fabric are welded-on in an easy operation by the calender and are simultaneously smoothed, so as to avoid the pilling effect or the nap or lint forming.

[0006] The apparatus advantageously includes a spun-bonding plant by means of which the filaments are deposited onto an endless belt that is embodied as a screen belt, as well as at least one downstream-connected needling device, an adjoining dryer, and at least one calender following the dryer.

[0007] According to a modification of the invention, the apparatus can optionally comprise a spun-bonding plant, a downstream-connected pre-needling device that can be admitted with low water pressure, an adjoining second needling device with thereto assigned at least one structuring drum with a suction box, as well as an adjoining dryer and at least one calender that follows the dryer.

[0008] It is furthermore advantageous if the apparatus includes a spun-bonding plant with downstream-connected pre-needling device that can be admitted with low water pressure, a following second needling device with at least one structuring drum, an adjoining dryer, and at least one calender following the dryer.

[0009] The apparatus is advantageously also provided with a spun-bonding plant, by means of which the filaments are deposited on the structuring drum, as well as the needling device that is directly assigned to the structuring drum, the adjoining dryer and at least the calender following the dryer.

[0010] Finally, according to a preferred embodiment of the inventive solution, the apparatus comprises the spun-bonding plant with downstream-connected pre-needling device that can be admitted with low water pressure, the adjoining second needling device that is provided with at least one structured drum, and a calender following the second needling device.

[0011] Of particular importance to the present invention is that at least one conveying drum is assigned to the structured drum, such that the endless belt is guided S-shaped or in the form of two semi-circles across the structured drum and the conveying drum. The different systems described in the above can be used to achieve a cost-effective production of an optimum nonwoven fabric for extreme use, which does not pillar.

[0012] In connection with the embodiment and arrangement according to the invention, the endless belt can advantageously be embodied as a conveyor belt or as a structured belt.

[0013] The invention relates to one-layer or multilayer nonwoven fabrics which are additionally and advantageously perforated by using one of the water needling processes. Nonwoven fabrics having a weight per unit area of 7-300 g/m.sup.2 are preferably processed. The processing speed is at least 100 m/min while the fiber strength--filament strength--preferably ranges from 0.4 to 10 dtex.

[0014] Additional advantages and details of the invention are explained in the patent claims and in the description and are illustrated in the Figures, which show in:

[0015] FIG. 1 A schematic representation of a spun-bonding plant with a downstream-arranged rotating belt on which the filaments are deposited, as well as a needling device, a dryer and a calender;

[0016] FIG. 2 A similar representation as shown in FIG. 1, for which the endless belt is guided S-shaped or in the form of two semi-circles over the drums;

[0017] FIG. 3 A similar representation as shown in FIG. 1, but where the endless belt is replaced by a drum;

[0018] FIG. 4 A similar representation as shown in FIG. 1, for which the endless belt is embodied only as a conveying element;

[0019] FIG. 5 A segment of the endless belt or a segment of a structured drum on which the filaments are deposited;

[0020] FIG. 6 A nonwoven fabric with numerous openings, which is processed on the endless belt.

[0021] The drawing shows a spun-bonding plant 1, which is used for depositing and further transporting endless filaments 4 on a continuously rotating belt 3 that is guided over four rollers 2, wherein at least one of the four rollers 2 is embodied as a drive roller.

[0022] The endless belt 3 is shown in further detail in FIG. 5. This belt is a screen belt composed of webs or wires 5, arranged spaced apart and extending at right angles to each other, between which small and approximately rectangular openings 6 are formed that allow the water 8 exiting from a needling device 7.1 to flow through these openings 6. Owing to the screen belt 3, the water is forced to travel longer distances and the individual filaments are displaced to the side, as shown in FIG. 6, thereby causing corresponding openings 6.1 to form in a nonwoven fabric 14, which openings match the shape of the openings 6 in the endless belt 3.

[0023] Following the needling operation, the nonwoven fabric 14 moves through a dryer 9, which can be embodied as infrared inline airflow dryer. The nonwoven fabric 14 is then smoothed with the aid of a calender 10, so that any filaments or loops or fibrils that still stick out are pushed back into the nonwoven fabric 14.

[0024] With the aid of the following calender 10, the projecting loops or fibrils are welded on and are simultaneously also pushed against the surface of the nonwoven fabric 14.

[0025] The above-described operational process and treatment of the nonwoven fabric 14 are realized in a similar manner in all systems shown in FIGS. 2 to 4.

[0026] According to the exemplary embodiment shown in FIG. 2, the nonwoven fabric 14 is supplied by the endless belt 3 to the water needling device 7.1 with a suction box 7.3, so that at this location the nonwoven fabric 14 can be roughly pre-compacted with low pressure. As a result, the nonwoven fabric 14 is compacted in such a way that it can subsequently be guided S-shaped or in the form of two semi-circles across two drums 11 and 12, wherein the second drum 12 is assigned an additional needling device 7.2 with a suction box 7.3. According to FIG. 4, the nonwoven fabric is taken over by the lower drum with the aid of suction pressure, is thus lifted off the screen belt with the aid of the drum 11 and is subsequently taken over by the drum 11 and, in the process, is transferred S-shaped to the drum 12 with thereto assigned suction box 7.3. The nonwoven fabric 14 is thus pushed against the drum 12.

[0027] The first drum 11 is a conveying drum while the second drum 12 is a structured drum, which corresponds to the endless belt 3, shown in FIG. 1, and is provided with numerous openings 6 corresponding to the screen belt or endless belt 3 shown in FIG. 5. The endless belt according to FIG. 2 is not embodied as a perforated belt, but only as a conveyor belt. The nonwoven fabric 14 is deposited on the conveyor belt 3, is then transferred to the drum 11 and is held thereon with the aid of a vacuum pressure. The perforation-creating openings provided in the drum 12 are thus used to create the openings 6.1 shown in FIG. 6 in the nonwoven fabric 14, with the aid of the water needling device 7.1, 7.2.

[0028] For the exemplary embodiment according to FIG. 3, the endless belt system according to FIG. 1 is replaced by a structured drum 13 with the needling device 7.1 and the suction box 7.3.

[0029] The exemplary embodiment shown in FIG. 4 does not comprise the dryer 9 between the two deflection drums 11, 12 and the downstream connected calenders 10.

REFERENCE NUMBER LIST

[0030] 1 spun-bonding plant [0031] 2 roller [0032] 3 endless belt, conveying belt, screen belt [0033] 4 endless filament [0034] 5 web, wire [0035] 6 opening in the endless belt [0036] 6.1 opening in the nonwoven fabric [0037] 7.1 needling device [0038] 7.2 needling device [0039] 7.3 suction box [0040] 8 water [0041] 9 dryer [0042] 10 calender [0043] 11 conveying drum [0044] 12 structured drum [0045] 13 structured drum [0046] 14 nonwoven fabric

Claims

1. A method for producing a one-layer or a multilayer nonwoven fabric with a plurality of yarn-type fiber groups or endless filaments, which are joined at least in the area of connecting locations, characterized in that following the water needling, the nonwoven fabric is smoothed with the aid of a calender.

2. The method according to claim 1, characterized in that following the water needling, the nonwoven fabric is smoothed with the aid of a calender and that the calender is adjusted in such a way that more than 90% of the tensile strength of the nonwoven fabric is retained in conveying direction.

3. The method according to claim 1, characterized in that relative to the water needling, the nonwoven fabric is reduced in volume by 25% to 15%, or 22 to 18%, or by approximately 20%.

4. The method according to claim 1, characterized in that the area subjected to pressure measures approximately 16% to 25%, or 17% to 22%, or 18% to 20% of the total surface area of the nonwoven fabric.

5. The method according to claim 1, characterized in that the nonwoven fabric is treated with a smoothing roll temperature of between 120.degree. and 155.degree., or between 125.degree. and 150.degree., or between 130.degree. and 150.degree., or between 140.degree. and 150.degree. C.

6. The method according to claim 1, characterized in that the nonwoven fabric is treated with an engraving temperature between 120.degree. and 155.degree., or between 125.degree. and 150.degree., or between 130.degree. and 150.degree., or between 140.degree. and 150.degree. C.

7. The method according to claim 1, characterized in that the nonwoven fabric is treated with an engraving temperature that is approximately between 120.degree. and 155.degree., or between 125.degree. and 150.degree., or between 130.degree. and 150.degree., or between 140.degree. and 150.degree. C., and that a line pressure of between 20 and 30 or between 24 and 28 N/mm is used during the subsequent calendering.

8. The method according to claim 1, characterized in that a drying operation takes place between the water needling and the calendering.

9. The method according to claim 1, characterized in that the nonwoven fabric is perforated (openings 6.1) as a result of the water needling.

10. The method according to claim 1, characterized in that a nonwoven fabric with a weight per unit area of 7 to 300 g/m.sup.2 is processed.

11. The method according to claim 1, characterized in that the processing speed is at least 100 m/min.

12. The method according to claim 1, characterized in that the nonwoven fabric has a fiber strength (diameter of the filaments) of between 0.4-10 dtex.

13. An apparatus for realizing the production method according to claim 1, characterized in that the apparatus comprises a spun-bonding plant, at least one downstream connected needling device and an adjoining dryer, which is followed by at least one calender.

14. The apparatus according to claim 13, characterized in that the apparatus comprises a spun-bonding plant for depositing the filaments on an endless belt, embodied as a screen belt, as well as at least one downstream connected needling device, an adjoining dryer, and at least one calender that follows the dryer.

15. The apparatus according to claim 13, characterized in that the apparatus comprises the following: a spun-bonding plant; a down-stream arranged pre-needling device that can be admitted with low water pressure; an adjoining second needling device with thereto assigned at least one structured drum with a suction box; an adjoining dryer; and at least one calender that follows the dryer.

16. The apparatus according to claim 13, characterized in that the apparatus comprises a spun-bonding plant, by means of which the filaments are deposited on a drum, as well as a needling device that is directly assigned to the drum, the adjoining dryer, and at least one calender that follows the dryer.

17. The apparatus according to claim 16, characterized in that the drum is embodied as a structured drum.

18. The apparatus according to claim 1, characterized in that at least one conveying drum is assigned to the structured drum, such that the endless belt is guided S-shaped or in the form of two semi-circles across the structured drum and the conveying drum.

19. The apparatus according to claim 16, characterized in that the endless belt is embodied as a conveying belt or as a structured belt.

20. A nonwoven fabric, characterized in that the nonwoven fabric is produced in accordance to claim 1.