WO2020024410A1

WO2020024410A1 - Method for producing a non-woven by means of a roller card

Info

Publication number: WO2020024410A1
Application number: PCT/CN2018/107792
Authority: WO
Inventors: Bodo Heetderks; Weiping Zhang
Original assignee: Truetzschler Gmbh & Co. Kg; Truetzschler Textile Machinery (Shanghai) Co. Ltd.
Priority date: 2018-07-31
Filing date: 2018-09-27
Publication date: 2020-02-06
Also published as: EP3830328A4; CN110777450B; EP3830328A1; CN110777450A

Abstract

It is disclosed a method and a roller card for producing a non-woven composed of synthetic fibres or man-made fibres produced from natural materials having a fibre length of from 12 to 25 mm and having a MD/CD ratio of less than 2: 1, wherein fibres or fibre tufts are supplied at the inlet side of a roller card (1) and, on a main cylinder (2), opened up into individual fibres and aligned by means of worker and stripper rolls (3, 4), then the resulting fibre web (20) is removed from the main cylinder (2) by means of at least two doffer rolls (5, 6), the diameters of the doffer rolls (5, 6) being at least 80 %of the diameter of the main cylinder (2), then the individual plies of fibre web being removed from each doffer roll (5, 6) by a respective condensing roll (7, 8) and deposited directly or indirectly on at least one transport belt (11, 12) and, immediately after the roller card (1), being joined and bonded to one another by means of hydrodynamic entanglement.

Description

Method for producing a non-woven by means of a roller card

Technical Field

The invention relates to a method for producing a non-woven composed of synthetic fibres or man-made fibres produced from natural materials having a fibre length of from 12 to 25 mm and having a MD/CD ratio of less than 2: 1. The invention further relates to a roller card and to a non-woven produced on the roller card.

Background Technology

The conventional roller card has a main cylinder from which the fibre web is removed at one or more locations. Each ply of fibre web is separately condensed and subsequently doubled or deposited only loosely one on top of the other on a removal device, for example a transport belt. Due to the operating principle of the roller card, the fibre web produced is anisotropic with a MD/CD ratio of more than 2: 1. The MD/CD ratio deteriorates further when synthetic fibres are processed. The fibre web must therefore be laid crosswise and overlapped multiple times in a cross-lapper and then bonded by means of a needling machine. The crosslapped and bonded non-woven then has a MD/CD ratio of from 1.1: 1 to 1.7: 1 and can be described as virtually isotropic. Both the crosslapper and the needling machine are expensive to buy and to operate, require a large amount of space and very much limit productivity.

In an alternative method, synthetic fibres, for example for producing wipes or cosmetic products, coming from a conventional roller card, undergo hydrodynamic entanglement by means of water jets, there being used in this case synthetic staple fibres having a length of 38 –52 mm. The non-woven so produced is likewise anisotropic with a MD/CD ratio of from 2.5: 1 to 3.5: 1. When shorter synthetic staple fibres having a length of 12 –25 mm are used, the MD/CD ratio deteriorates even further.

EP0661394 B1 describes a roller card of the applicant, in which the doubling and condensing of the fibre web plies is effected on the first or second condensing roll. Such a roller card has the disadvantage that the carding output for short synthetic fibres having a length of 12 –25 mm is very poor. The fibre web created on such a roller card has a MD/CD ratio of more than 3: 1 and is unsuitable for use as a wipe or cosmetic product without further processing by means of a crosslapper.

Summary of the Invention

The object of the invention is to provide an economical method for producing an isotropic non-woven composed of short synthetic fibres. A further object of the invention is to provide a roller card with which the method can be carried out.

The invention solves that problem by the teaching according to

claims

1, 7 and 15. Further advantageous structural features of the invention are characterised by the subsidiary claims.

According to the technical teaching of claim 1, the method for producing a non-woven composed of synthetic fibres or man-made fibres produced from natural materials having a fibre length of from 12 to 25 mm and having a MD/CD ratio of less than 2: 1, comprises a roller card to which fibres or fibre tufts are supplied at the inlet side of the roller card and, on a main cylinder, opened up into individual fibres and aligned by means of worker and stripper rolls.

The resulting fibre web is removed from the main cylinder by means of at least two doffer rolls, the diameters of the doffer rolls being at least 80%of the diameter of the main cylinder and the individual plies of fibre web being removed from each doffer roll by a respective condensing roll and deposited directly or indirectly on at least one transport belt and, immediately after the roller card, being joined and bonded to one another by means of hydrodynamic entanglement.

Because the doffer rolls have the same or virtually the same diameter as the main cylinder, on the one hand a higher carding output is obtained and on the other hand the synthetic fibres can be aligned relative to one another in a more specific way. As a result of increasing the diameters of the doffer rolls to the diameter of the main cylinder, the previously high degree of curvature of the roll surfaces becomes more approximate to a straight line, so that the carding output is improved. Especially in the case of short synthetic fibres or in the case of man-made fibres produced from natural materials, more precise alignment of the individual fibres takes place, so that a non-woven having greater isotropy can be produced. The subsequent bonding of the fibre webs by means of hydrodynamic entanglement makes it possible to do without an expensive crosslapper. As a result of the roll diameters being approximately the same, the higher carding output is achieved by a higher transfer factor of from 18 %to 23 %per doffer. The transfer factor in accordance with the prior art is usually from 10 %to 15 %per doffer.

Preferably the fibres have a length of at least 20 –25 mm. The greater fibre length is advantageous for the hydroentangling that is effected after the carding, because the slightly longer fibres can be better intermingled with one another.

In a preferred embodiment, the MD/CD ratio of the non-woven is from 1.4: 1 to 1.9: 1, which is virtually isotropic and therefore does not need further processing by means of a crosslapper and a needling machine.

Advantageously the hydrodynamic entanglement can be effected with at least one water beam at a pressure of at least 20 bar up to a maximum of 80 bar. By limiting the pressure range, washing-out of short fibres is avoided or reduced.

Advantageously the fibre web is compacted or condensed between the main cylinder and the doffer rolls by a factor of from 5 to 12. The subsequent condensing of the fibre web between the doffer rolls and the condensing rolls by a factor of from 1.5 to 2.5 creates the required MD/CD ratio, with which the resulting non-woven can be described as virtually isotropic.

The roller card according to the invention for producing a non-woven comprises an inlet side to which fibres or fibre tufts are supplied. On a main cylinder the fibres or fibre tufts are opened up into individual fibres and aligned by means of worker and stripper rolls. The resulting fibre web is removed from the main cylinder by means of at least two doffer rolls. According to the invention the diameters of the doffer rolls are at least 80 %of the diameter of the main cylinder, the individual plies of fibre web being removed from each doffer roll by a respective condensing roll and deposited directly or indirectly on at least one transport belt.

Because the doffer rolls have the same or virtually the same diameter as the main cylinder, on the one hand a higher carding output is obtained and on the other hand the synthetic fibres can be aligned relative to one another in a more specific way. As a result of increasing the diameters of the doffer rolls to the diameter of the main cylinder, the previously high degree of curvature of the roll surfaces becomes more approximate to a straight line, so that the carding output is improved. Especially in the case of short synthetic fibres or in the case of man-made fibres produced from natural materials, more precise alignment of the individual fibres takes place, so that a non-woven having greater isotropy can be produced. As a result of the roll diameters being approximately the same, the higher carding output is achieved by a higher transfer factor of from 18 %to 23 % per doffer. The transfer factor in accordance with the prior art is usually from 10 %to 15 %per doffer.

Preferably the main cylinder has a diameter of from 350 to 650 mm. Compared to the prior art, that diameter range is small. Roller cards having a main cylinder diameter of up to 1500 mm have higher productivity, because the non-woven created is multiply layered and then bonded on the subsequent crosslapper. The smaller diameter range of the main cylinder herein is especially suitable for integration into a manufacturing line for a lightweight non-woven which is subsequently processed directly to the end product with only a small number of further manufacturing steps.

In keeping therewith, the doffer rolls have the same or virtually the same diameter of from 350 to 550 mm, so that the carding surface is as large as possible.

Preferably the doffer rolls have the same diameter as the main cylinder, so that they differ only in the clothing and the rotational speed.

In an advantageous embodiment, the condensing rolls also have the same diameter. The similar nature of the parts means that the roller card can be produced very economically.

Due to the low non-woven weights of 20 –60 g/m ², the condensing rolls are preferably suctioned from the inside, so that the lightweight fibre web is transferred as completely as possible.

In accordance with an advantageous embodiment, the main cylinder, the doffer rolls and the condensing rolls have the same diameter. The rolls then differ only in the clothing that has been applied, thus making the roller card apparatus very economical to produce.

The non-woven according to the invention consists of synthetic fibres or man-made fibres produced from natural materials which have a fibre length of from 12 to 25 mm. The carded non-woven has a MD/CD ratio of less than 2: 1, with a weight of from 20 to 60 g/m ² and does not require any further processing, for example in a crosslapper or in a needling machine, prior to the hydroentangling.

Preferably the fibres have a linear density of from 1.0 to 2.2 dtex, prefer-ably from 1.2 to 1.7 dtex, with which it is possible to produce very lightweight non-wovens composed of short fibres.

Advantageously the fibres have a length of from 20 to 25 mm, so that the resulting non-woven acquires higher strength in the subsequent hydro-dynamic entanglement.

Because the roller card and the method according to the invention make it possible to adjust the MD/CD ratio to from 1.4: 1 to 1.9: 1, a virtually isotropic non-woven is produced which can be used as a hygiene article or cosmetic article without further laborious processing.

Brief Description of the Drawings

The invention is explained in greater detail below with reference to a possible exemplary embodiment which is shown diagrammatically in the drawing, wherein

Figure 1: shows a roller card according to the invention.

Description of the Embodiments

Figure 1 shows the roller card 1 according to the invention which has an inlet side 1a for fibre tufts and two

outlet sides

1 b, 1c for a fibre web 20.

In the roller card 1, the fibre tufts are supplied at the inlet side of the apparatus and fed via rolls (not shown herein) of a breast cylinder or directly to the main cylinder 2 on which, in a first step, the fibre tufts are opened up into individual fibres and aligned. During the operation of transporting the fibre tufts on the main cylinder 2, stripper and worker rolls 3, 4 hold the fibres on the main cylinder 2, so that a first fibre web 20 is formed. The main cylinder 2 rotates in the clockwise direction and its clothing or teeth are likewise inclined in the clockwise direction, that is to say in the direction of rotation. An upper doffer roll 5 takes up a first layer of the fibre web 20 and in so doing rotates in the anticlockwise direction. The remaining second layer of the fibre web 20 is removed from the main cylinder 2 by a lower doffer roll 6 which likewise rotates in the anti-clockwise direction. The clothings or teeth of both doffer rolls 5, 6 are inclined in the clockwise direction and contrary to the direction of rotation of the doffer rolls 5, 6. The doffer rolls 5, 6 preferably have the same diameter.

A subsequently arranged condensing

roll

7, 8 takes up a ply of fibre web 20 from the upper and the

lower doffer roll

5, 6, respectively. The condensing rolls 7, 8 again rotate in the clockwise direction, the clothing or teeth thereof being inclined in the anticlockwise direction. A subsequently arranged

transfer roll

9, 10 guides the fibre web 20 from the

respective condensing roll

7, 8 to a

transport belt

11, 12, on which the two plies of fibre web 20 are brought together and are joined and bonded to form a non-woven 21 by means of hydrodynamic entanglement by at least one water beam 13 having a suction device 14. The water beam (s) 13 are operated at a pressure of at least 20 bar, the maximum pressure being limited to 80 bar in order to avoid washing-out of short fibres.

The main cylinder 2 has, for example, a diameter of 350 –650 mm, preferably 413 mm. According to the invention the doffer rolls 5, 6 have virtually the same diameter which is at least 80 %of the diameter of the main cylinder. In this exemplary embodiment the diameter of the doffer rolls 5, 6 can be at least 350 –500 mm, preferably likewise 413 mm, the doffer rolls 5, 6 having the same diameter. The increase in the diameters of the doffer rolls 5, 6 to the same or virtually the same diameter as the main cylinder 2 (at least 80 %of the diameter of the main cylinder 2) on the one hand enhances the carding action, but also reduces the centrifugal forces acting on the fibres, so that fibre fly is reduced. Especially in the case of short synthetic fibres having a fibre length of 12 –25 mm, the increase in the diameters of the doffer rolls 5, 6 has a positive effect such that the fibres are oriented isotropically in a MD/CD ratio of from 1.4: 1 to 1.9: 1 so that it is subsequently possible to do without an expensive crosslapper and a needling machine. As a result of increasing the diameters of the doffer rolls 5, 6, the previously high degree of curvature of the roll surfaces becomes more approximate to a straight line, so that the carding output is increased. Especially in the case of short synthetic fibres or in the case of man-made fibres produced from natural materials, more precise alignment of the individual fibres takes place, so that a non-woven having greater isotropy can be produced.

The operation of both identically sized doffer rolls 5, 6 at the same circumferential speed provides for the same draft during transfer of the fibre web 20 to the condensing rolls 7, 8. Preferably the condensing rolls 7, 8 have the same diameter.

Alternatively, the doffer rolls 5, 6 can also be operated at different circumferential speeds, so that each ply of fibre web is condensed differently and accordingly has a different density. This is advantageous for products in which the density is to be variable over the cross-section.

The effect according to the invention occurs advantageously in the case of synthetic fibres, such as, for example, polyester, or polypropylene, or man-made fibres produced from natural materials (regenerated fibres) , such as, for example, pulp, cellulose, viscose or lyocell.

The use of short fibre lengths of 12 –25 mm, preferably 20 –25 mm, enables economical products to be produced, because such fibre lengths can otherwise be processed only in a significantly more laborious procedure, for example in a wet-laid process, which is possible only using a very complex and energy-intensive machine. The use of fibre lengths of 20 –25 mm is advantageous for the subsequent hydrodynamic entanglement, because the longer fibres are better intermingled with one another and the end product acquires greater strength.

For the production of lightweight non-wovens having a weight of 20 -60 g/m ², the fibres have a linear density of from 1.0 to 2.2 dtex, preferably from 1.2 to 1.7 dtex. Preferably the non-wovens produced in accordance with the method of the invention are used as hygiene products (wipes) or as cosmetic products.

The following first exemplary embodiment relates to the configuration of an exemplary roller card of 2.5 m working width in accordance with the prior art. The roll diameters indicated do not include the height of the clothing.

Roll pos.	Roll diameter [mm]	Speed [m/min]	Roll rotation direction
2	1200	1200	right
5	550	200	left
6	550	200	left
7	413	120	right
8	413	95	right

The resulting non-woven composed of PET/CV fibres has a non-woven weight of 40 g/m ² with a fibre length of 38 –40 mm and has a MD/CD ratio of 3.3 –3.8.

In the second exemplary example in accordance with the invention, the main cylinder 2, the doffer rolls 5, 6 and the condensing rolls 7, 8 were implemented with the same diameter.

Roll pos.	Roll diameter [mm]	Speed [m/min]	Roll rotation direction
2	413	1200	right
5	413	200	left
6	413	200	left
7	413	120	right
8	413	95	right

The resulting non-woven composed of PET/CV fibres has a non-woven weight of 40 g/m ² with a fibre length of 18 –25 mm and has a MD/CD ratio of 1.7 –1.9.

According to the invention, by virtue of its smaller diameter the main cylinder 2 has, at the same circumferential speed, a higher rotational speed. The associated centrifugal force results in a higher transfer factor and an improvement in the random fibre layer.

Reference signs

1 roller card

1a inlet side

1b outlet side

1c outlet side

2 main cylinder

3 stripper roll

4 worker roll

5 doffer roll

6 doffer roll

7 condensing roll

8 condensing roll

9 transfer roll

10 transfer roll

11 transport belt

12 transport belt

13 water beam

14 suction device

20 fibre web

21 non-woven

Claims

Method for producing a non-woven composed of synthetic fibres or man-made fibres produced from natural materials having a fibre length of from 12 to 25 mm and having a MD/CD ratio of less than 2: 1, wherein fibres or fibre tufts are supplied at the inlet side of a roller card (1) and, on a main cylinder (2) , opened up into individual fibres and aligned by means of worker and stripper rolls (3, 4) , and the resulting fibre web (20) is removed from the main cylinder (2) by means of at least two doffer rolls (5, 6) , the diameters of the doffer rolls (5, 6) being at least 80 %of the diameter of the main cylinder (2), and the individual plies of fibre web being removed from each doffer roll (5, 6) by a respective condensing roll (7, 8) and deposited directly or indirectly on at least one transport belt (11, 12) and, immediately after the roller card (1) , being joined and bonded to one another by means of hydrodynamic entanglement.
Method according to claim 1, characterised in that the fibres have a length of at least 20–25 mm.
Method according to claim 1 or 2, characterised in that the MD/CD ratio is from 1.4: 1 to 1.9: 1.
Method according to claim 1, characterised in that the hydro-dynamic entanglement is effected with at least one water beam at a pressure of at least 20 bar.
Method according to any one of the preceding claims, character-ised in that the fibre web (20) is compacted or condensed between the main cylinder (2) and the doffer rolls (5, 6) by a factor of from 5 to 12.
Method according to any one of the preceding claims, character-ised in that the fibre web (20) is condensed between the doffer rolls (5, 6) and the condensing rolls (7, 8) by a factor of from 1.5 to 2.5.
Roller card for producing a non-woven, wherein fibres or fibre tufts are supplied at the inlet side of a roller card (1) and, on a main cylinder (2) , opened up into individual fibres and aligned by means of worker and stripper rolls (3, 4) , and the resulting fibre web (20) is removed from the main cylinder (2) by means of at least two doffer rolls (5, 6) , characterised in that the diameters of the doffer rolls (5, 6) are at least 80 %of the diameter of the main cylinder (2) , and the individual plies of fibre web are removed from each doffer roll (5, 6) by a respective condensing roll (7, 8) and deposited directly or indirectly on at least one transport belt (11, 12) .
Roller card according to claim 7, characterised in that the main cylinder (2) has a diameter of from 350 to 650 mm, preferably 413 mm.
Roller card according to claim 7, characterised in that the doffer rolls (5, 6) have a diameter of from 350 to 550 mm, preferably 413 mm.
Roller card according to claim 9, characterised in that the doffer rolls (5, 6) have the same diameter.
Roller card according to claim 7, characterised in that the condensing rolls (7, 8) have the same diameter.
Roller card according to any one of preceding claims 7 to 11, characterised in that the condensing rolls (7, 8) are suctioned from the inside.
Roller card according to any one of preceding claims 7 to 12, characterised in that the main cylinder (2) , the doffer rolls (5, 6) and the condensing rolls (7, 8) have the same diameter.
Roller card according to any one of preceding claims 7 to 13, operated in accordance with the method of claims 1 to 6.
Non-woven composed of synthetic fibres or man-made fibres produced from natural materials having a fibre length of from 12 to 25 mm and having a MD/CD ratio of less than 2: 1, with a weight of from 20 to 60 g/m ².
Non-woven according to claim 15, characterised in that the fibres have a linear density of from 1.0 to 2.2 dtex, preferably from 1.2 to 1.7 dtex.
Non-woven according to claim 15 to 16, characterised in that the fibres have a length of from 20 to 25 mm.
Non-woven according to any one of claims 15 to 17, characterised in that the MD/CD ratio is from 1.4: 1 to 1.9: 1.
Non-woven according to any one of claims 15 to 18, for use as a hygiene article or cosmetic article.
Non-woven according to any one of claims 15 to 19, produced on a roller card according to any one of claims 7 to 14 in accordance with the method of claims 1 to 6.