JP2005531701A - Method and apparatus for making air-borne fibers - Google Patents

Abstract

The present invention relates to a process for producing a flow of airborne fibres, characterized by the following stages: a) a continuous length (2) of a thread bundle of fibre material is fed from a stock (1) of fibre material through a roll press (4), which rotates at a rate of feed and with the thread bundle held fast in the nip between its rollers (11, 12), b) on emerging from the roll press (4), individual fibres are broken off from the thread bundle by means of a tearer (5), c) the individual fibres broken off by the tearer are carried away from the tearer by means of an air flow.

Description

  The present invention relates to a method and apparatus for making air-borne fibers from a continuous length of fiber material yarn bundles.

  In the manufacture of absorbent articles such as diapers, incontinence pads, sanitary napkins and the like, a number of different types of materials made from various types of synthetic fibers are used. The most commonly found materials are various types of so-called nonwoven materials, which are mainly used as the liquid permeable surface layer of absorbent articles. The liquid permeable surface layer is disposed on the side of the article that is directed toward the user during use. Another common type of material made from synthetic fibers is so-called stuffed cotton, which is placed directly inside the liquid-permeable surface layer of the absorbent article and is the first of the liquid that enters the article The user uses it as an insertion material that functions as a temporary storage material.

  There are also other applications of synthetic fiber materials in absorbent articles.

  The basic material for the production of synthetic fiber materials for absorbent articles is the continuous length of the yarn bundle (tow), which was predetermined in a separate step before the nonwoven material or stuffed cotton was produced Cut to length. Patent WO-A1-93 / 11288 shows an apparatus for feeding a yarn bundle of synthetic fiber material to a cutting device, where the yarn bundle is cut to a specific length.

  The cut fibers are then usually packed for delivery to the manufacturer of the nonwoven or stuffed cotton material.

  Regardless of whether they go to a non-woven fabric manufacturer or a stuffed cotton manufacturer, the packed fibers are separated from each other in a first stage, and then the fibers are fed into a manufacturing process in which a so-called fiber layer is created. A common technique for making fiber layers is carding. The fiber layer is finally hardened together by a suitable method so that it can be handled and the material can be introduced into a machine for producing absorbent articles and wound on rolls etc. To give non-woven material or cotton pad

  Attempts have also been made to introduce fibers from the packaging into the air stream and create a fiber layer on a vacuum wire, the so-called mat former. The mat forming technique is much easier and more durable than carding.

  However, this technique has proven to be too coarse and insensitive, and a major problem occurs when the packed fibers must be separated from one another without forming fiber scraps. Fiber scraps cause uneven nonwoven or stuffed cotton material that does not function satisfactorily and is not aesthetically acceptable.

  Therefore, it is possible to make air-borne fibers with a uniform distribution of fibers in the air stream without noticeable generation of fiber scraps in the air stream from the continuous length of the yarn bundle of fiber material, thus making the fiber layer There is a need for a method and apparatus that can use a robust mat forming technique.

  The object of the present invention is to fulfill this need.

This purpose is the next stage:
a) A continuous length of fiber material yarn bundle is fed from a fiber material reservoir through a roll press, the roll press rotates at a feed rate and has a yarn bundle firmly held in the nip between the rollers ing,
b) Upon exiting the roll press, the individual fibers are torn from the yarn bundle by the disrupter,
c) Individual fibers that have been torn by the fissure are carried away from the fission by an air stream,
This is achieved by a method for producing an air-borne fiber stream characterized in that it comprises:

  This method proves to give a substantially more uniform distribution of the fibers in the air stream, while the generation of fiber debris in the air stream is generally negligible compared to previously known methods.

  In a preferred embodiment, the splitter comprises a rotary splitter, which is rotated at a peripheral speed greater than 600 m / min, preferably greater than 1200 m / min, more preferably greater than 1500 m / min. The length of the fiber carried by the air is adjusted by changing the distance between the roll press and the breaker, and the amount of fiber carried by the air is changed by changing the rotational speed of the roll press, i.e. the yarn bundle inlet feed rate. It is adjusted by adjusting.

  The invention also relates to a device for making air-borne fibers having a defined length distribution from a yarn bundle of fiber material, which device is a fiber material reservoir, yarn in the form of a continuous length of yarn bundle A roll press having an inlet side and an outlet side for the bundle, a breaker arranged adjacent to the outlet side of the roll press, an opening on the side facing the outlet side of the roll press and containing the breaker, and air It includes a housing including an inlet and an air outlet disposed on the opposite side, and an element for creating an air flow through the housing from the air inlet to the air outlet.

  In a preferred embodiment, the roller of the roll press has a series of axial ribs that are evenly distributed along the circumference of the roller and extend over the entire length of the roller, and the ribs on one roller are second when the roller rotates. Engage within the spacing between the ribs on the rollers. The splitting device preferably takes the form of a rotating splitting roller, and the device advantageously has an element for moving the roll press radially with respect to the splitting roller. The element for creating an air flow through the housing from the air inlet to the air outlet includes a blower, the outlet side of which is connected to the air inlet of the housing.

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be described with reference to the accompanying drawings.
In the drawing:
FIG. 1 shows a schematic side view of a device according to a preferred embodiment of the invention connected to a mat-forming wheel,
FIG. 2 shows a schematic perspective view of a roll press forming part of the apparatus according to FIG.
FIG. 3 shows the shape of the disrupter teeth forming part of the device according to FIG.

  FIG. 1 shows a schematic view of an apparatus for air depositing on a mat former 3 a continuous fiber length of a synthetic fiber yarn bundle 2, a layer of such fibers taken from a so-called tow storage reel 1. Such a fiber layer is suitable as an insertion layer for absorbent products such as sanitary napkins, diapers and the like. The apparatus includes a roll press 4 that supplies a yarn bundle length 2 to a splitting device 5, such as a splitting device from Zuiko. The disrupter 5 is provided inside the housing 6, which has an inlet supply opening through which the tow 2 runs. The housing further has an air inlet 7 and an air outlet 8 arranged in two opposing walls, which extend in a direction perpendicular to the wall containing the inlet supply opening in the embodiment shown. The outlet side of the blower 9 is connected to the air inlet 7 of the housing, and the outlet funnel 10 extends from the air outlet 8 of the housing to just outside the peripheral surface of the mat former 3. Alternate arrangements of air inlets and air outlets are also conceivable.

  FIG. 2 shows a schematic perspective view of the roll press 4. As can be seen from this figure, the rollers 11, 12 forming part of this roll press have ribs running in the axial direction, which extend over the entire length of the roller and are evenly distributed around the circumference of the roller. Yes. The rollers 11 and 12 are further arranged so that the ribs 13 of one roller extend within the interval between the ribs 13 of the second roller when the roller rotates. The support surface between the tow and the peripheral surface of the roller will thereby be relatively large. On the other hand, the tow is wound through a roll nip between the rollers 11 and 12 of the roll press 4. The tow hook is thereby held tightly between the rollers so that the fibers are split without the tow hook slipping between the rollers.

The splitter 5 shown schematically in FIG. 1 includes a rotatable cylindrical splitter of a type similar to that used in carding fiber material. Such a disruptor has a continuous toothed wire wound around the circumference of the cylinder over the entire length of the cylinder. FIG. 3 shows the typical shape of such a wire. The wire has a width of 0.5-1 mm, which means that the inclination of the wire winding in the transverse direction of the cylinder made by the winding will be relatively small. Such a disruptor typically has a tooth point / cm ² between 60 and 120. During operation of the device, the splitting device 5 rotates with a high peripheral speed far exceeding the supply speed of the tow. The rotation speed of the disrupter is greater than 600 m / min, preferably greater than 1200 m / min, more preferably greater than 1500 m / min. The high peripheral speed of the disruptor means that the tow is not pulled but is torn / split.

  This device functions to split the yarn in the tow so that the splitting teeth catch the tow from the roll nip between the rollers 11 and 12. Since the splitter has a high tooth density, the individual fibers will be split. The split fibers are then blown from the splitting teeth by the air flow generated by the blower 9 and transported through the exit funnel 10 to the mat former wheel 3 where the fibers are air permeable extending along the periphery of the mat former wheel. Collected in a mold. There is usually a negative pressure under the base of these molds.

  Due to the fact that the peripheral speed of the fission device is considerably higher than that of the rollers 11, 12, the tow can be regarded as stationary with respect to the fission device. The tow yarns are also held firmly and securely in the roll nip between the rollers 11, 12, so that they cannot slide with respect to the roller or be stretched at the roll nip.

  After passing through the roll press 11, 12, the continuous fiber yarn is exposed to the air flow generated by the high speed breaker 5. The air flow deflects the fibers in the direction of the air flow, and each individual fiber vibrates freely in the air flow until it encounters the disrupter teeth. The length of each individual yarn fluctuates when encountering one of the splitting teeth, which is mainly how long the airflow from the splitting device 5 before the fiber yarn in question encounters the surface of the splitting device 5. It depends on whether it can vibrate freely. That is, it depends on the time it takes in the housing 6.

  The important parameters that affect the time that individual fiber yarns are consumed by them before encountering the splitter 5, and therefore their length, are the distance between the roll presses 11, 12 and the splitter 5, the splitter 5 And the strength of the air flow formed thereby, the inlet supply speed of the roll presses 11 and 12, and the fluctuations in the stiffness of various fiber yarns.

  When one of the splitter teeth finally encounters a fiber thread, that fiber thread is torn at the point of impact due to the large force and fast continuity that the splitter 5 acts on the fiber thread.

  The length of the split fiber is therefore dependent on a number of parameters, but the most important of these is how much time it consumes in the housing 6 without encountering the splitter 5 It is a somewhat chaotic parameter.

  With regard to fiber length distribution, split fibers can be divided into three main categories.

  The first category includes relatively short fiber yarns. These short fibers have been split from the continuous yarn bundle, i.e., encountered in the splitter 5 after consuming a relatively short time in the housing 6. This category includes an estimated 25% of the total percentage of split fibers.

  The second category represents approximately 50% of the split fibers and consists of fibers split from the yarn bundle after a slightly longer time.

  The third category consists of longer fibers with large variations in length. Perhaps a relatively long time has passed before the fissure tries to grab these fibers. The proportion of this third category of fibers is approximately 25% of the total amount of fibers. This blend of longer fibers has a positive impact on the quality of the fiber layer produced. This is because some mixing of long fibers acts as an effective reinforcement for the fiber layer being made.

  Typical fiber lengths are 5-40 mm for category 1 (short fibers), 40-70 mm for category 2, and 70-150 mm (polyester fibers) for category 3.

  Other fiber length distributions can of course also be created by modifying the distance between the rollers 11, 12 and the disrupter.

  In some applications it may be advantageous to make fiber length variations greater than the natural variations described above. It can be achieved in a number of ways.

  One way is to change the diameter of the disrupter 5 over its axial extent so that the distance between the roll presses 11, 12 and the disrupter 5 varies in the axial direction. The fact that the distance between the rolls 11, 12 and the surface of the splitter 5 varies over the axial extent of the splitter is the time spent before they are encountered by the splitter 5 in the housing 6 by the fiber thread. Also means that the fiber yarn will vary depending on the width at which it is fed into the housing 6, i.e. depending on the fiber yarn inlet feed position with respect to the splitter 5.

  Another way to create fiber length variation is to use a separate air flow to positively control the length of time that the fiber yarn spends in the housing 6 before the teeth of the splitter 5 grab the fiber yarn. It is. This control can be performed by an air jet located in the upper part of the housing 6, creating an air flow that rests on the air flow produced by the rotation of the disrupter 5. The tow is thereby deflected so that the time spent in the housing 6 before the fiber yarn encounters the teeth of the splitter 5 is adjusted. The jet can be arranged so that only a limited portion of the tow rope width is guided while the other portions are not guided. It is also possible to place a plurality of jets that provide air flow in different directions and that guides the wide part of the tow rope, so the time spent before contacting the teeth of the disrupter 5 And other jets create an air flow that extends the time spent.

  A further advantage of the additional deflected air from the jet as described above is that it also has a cooling effect on the device.

  It has been shown that the above-described method of making air-borne fibers from tow rope and air-depositing the fibers produces an aerated fiber layer with a very well-defined distribution of fibers in the layer. Furthermore, very little if any fiber waste occurs in the layer. The method described above is much easier to implement than current carding technology. It is not entirely clear why the method described above leads to such good results. However, one contributing reason is probably the fact that effective separation of the fibers occurs at the moment of splitting, and the fact that the fibers are then kept separated from each other until a fiber layer is created. Another contributing factor is that each fiber to be split has a well-defined direction perpendicular to the direction of rotation of the disrupter since the yarn is stretched before the fiber is split. It may be. In addition, fibers that are subsequently split at intervals between splits may reduce the risk of forming debris by being trapped in previously split fibers.

  Various additional materials can be easily mixed into the fiber layer produced by the method described above. Examples of additional materials are other grades of fibers, granular superabsorbent gel-forming polymers, so-called superabsorbent materials and the like. Mixing is preferably performed in conjunction with the air flow generated by the blower 9 after the fibers have passed through the disruptor. Mixing can be placed anywhere between the blower 9 and the mat former 3.

  The embodiments described above can naturally be modified without departing from the scope of the invention. For example, a tow can be placed in some way other than on a storage reel, for example, placed in a container. The ribs on the rollers forming part of the roll press can have several other cross-sections, the top of which is advantageously rounded, for example. The air flow can be created by vacuum instead of a blower. The housing that houses the disruptor can have other shapes, for example, designed to narrow towards the air outlet. In addition, other types of breakers can be used, and the roll press can be designed in several other ways to hold the tow rope firmly and securely in its roll nip, for example tow. In order to increase the support surface for this roller of the lasso, it is designed to press the tow limp against the circumference of one of the rollers of the roll press. In addition, the roll press can advantageously be displaceably supported so that the distance between the roller and the perimeter of the disrupter is adjustable. It is also possible to provide a roller and a breaker having a width so that a plurality of tow lobes arranged side by side can simultaneously pass through the device. Accordingly, the invention should be limited only by the terms of the appended claims.

Fig. 2 shows a schematic side view of a device according to a preferred embodiment of the invention connected to a mat-forming wheel. Fig. 2 shows a schematic perspective view of a roll press forming part of the apparatus according to Fig. 1; Fig. 2 shows the shape of the disrupter teeth forming part of the device according to Fig. 1;

Claims (10)

In the method for creating an air-borne fiber stream, the following steps:
a) A continuous length (2) of fiber material yarn bundles is fed from a fiber material reservoir (1) through a roll press (4), the roll press is rotated at a certain feed speed, its rollers (11, 12) Have a tightly held yarn bundle in the nip between,
b) Upon exiting the roll press (4), the individual fibers are torn from the yarn bundle by the disrupter (5).
c) Individual fibers that have been torn by the fissure are carried away from the fission by an air stream,
A method comprising the steps of:   That the splitter (5) comprises a rotary splitter and that the splitter (5) is rotated at a peripheral speed greater than 600 m / min, preferably greater than 1200 m / min, more preferably greater than 1500 m / min. The method of claim 1, characterized in that:   3. A method according to claim 2, characterized in that the length of the fiber carried by the air is adjusted by changing the distance between the roll press (4) and the disrupter (5).   The method according to claim 2 or 3, characterized in that the amount of fiber carried by the air is adjusted by changing the rotational speed of the roll press (4).   In a device for producing air-borne fibers having a defined length distribution from a yarn bundle (2) of fiber material, the device is a storage (1) of fiber material in the form of a continuous length (2) of yarn bundles (1) ), A roll press (4) having an inlet side and an outlet side for a bundle of yarns, a breaker (5) arranged adjacent to the outlet side of the roll press, on the outlet side of the roll press containing the breaker A device comprising a housing (6) comprising an opening on opposite sides and an element (7, 8, 9) for creating an air flow through the housing (6).   An element for creating an air flow through the housing (6), an air outlet (8) arranged on the opposite side of the air inlet (7) and the housing (6), and an air flow through the housing from the air inlet to the air outlet Device according to claim 5, characterized in that it comprises:   The rollers (11, 12) of the roll press (4) have a series of axial ribs (13) that are evenly distributed around the circumference of the rollers and extend over the entire length of the rollers, and the ribs (13 The device according to claim 5 or 6, characterized in that it engages within the spacing between the ribs (13) on the second roller as the roller rotates.   8. A device according to claim 5, 6 or 7, characterized in that the splitting device (5) comprises a rotating splitting roller.   9. Device according to claim 8, characterized in that the device comprises an element for moving the roll press (4) in the radial direction with respect to the splitting roller (5).   10. Element according to claim 5, characterized in that the element for creating an air flow through the housing from the air inlet to the air outlet comprises a blower (9), the outlet side of which is connected to the air inlet (7) of the housing. A device according to the above.

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