JP4326899B2 - Nonwoven manufacturing method - Google Patents

Description

  The present invention relates to a method for producing a nonwoven fabric having high density, excellent flexibility, and soft texture.

  A technique for forming a nonwoven fabric by injecting a water stream onto a short fiber layer on a papermaking net produced by a wet method obtained by papermaking a short fiber, for example, a fiber having a fiber length of 10 mm or less is known. Yes (see, for example, Patent Document 1). In this case, if the short fiber layer formed on the paper machine net (hereinafter referred to as the paper machine net) is entangled with the water flow on the paper machine net as it is, the short fiber layer is shortened by the water jetted from the high pressure nozzle. There was a problem that some fibers in the fiber layer were entangled with the papermaking net. In particular, if the thin part of the short fiber layer that occurs during papermaking, the thin part at both ends of the short fiber layer, or the thin part of both ends of the short fiber layer that occurs during papermaking troubles get tangled in the papermaking network, There was a problem that it could not be removed and production was not possible. In addition, in the case of a plastic papermaking net, there is also a problem that short fibers are easily entangled at the joint. As described above, in the case where the water flow is continuously jetted on the papermaking net and the short fibers are entangled, there are many problems that the production efficiency is remarkably lowered. Therefore, a method of moving the short fiber layer from the papermaking net to another support for entanglement and then tangling the short fibers by jetting a water flow can be considered. However, in this case, there is a problem that a trouble occurs in which the fiber structure of the short fiber layer is disturbed or broken. In particular, in the case of fibers that are easily entangled with the papermaking net, transfer is difficult.

JP-A-2-127551 (Claim 2)

  This invention makes it a subject to solve said problem, and provides the manufacturing method of the nonwoven fabric which does not produce the problem which a short fiber entangles with a papermaking net | network.

In the present invention, a fiber sheet made of a nonwoven fabric having an areal density of 5 to 100 g / m ² , an average fiber diameter of 10 to 80 μm, and a tensile strength when wet of 5 N / 5 cm or more is placed on a net of a paper machine. Forming a short fiber layer on the fiber sheet by paper making a slurry in which short fibers are dispersed in water, and then spraying a water flow from the short fiber layer side to form a short fiber entangled layer and the fiber A method for producing a nonwoven fabric comprising: forming a laminate composed of a sheet, separating the fiber sheet from the laminate, and producing a nonwoven fabric composed of the short fiber entangled layer.

  According to the production method of the present invention, even if the short fibers are entangled by jetting water flow on the paper mesh, the fibers are not entangled with the paper mesh. Easier to do. In addition, even short fibers that are difficult to transfer after papermaking can be easily entangled.

  Hereinafter, preferred embodiments of the method for producing a nonwoven fabric according to the present invention will be described in detail.

  The paper machine may be one that is normally used for paper making, and for example, an inclined type, long net type, or round net type paper machine can be applied. The papermaking net is also a net normally used in papermaking, and a net used in a process of rolling up paper from a slurry mainly composed of pulp or synthetic fiber can be applied. Examples of the material of the net include metal and plastic, and the form is a monofilament, a multifilament, a strand made of natural fiber, recycled fiber, and / or synthetic fiber, or a net such as a felt shape. Can be applied. The weaving method and the fineness of the eyes are not particularly limited.

  The fiber sheet refers to a sheet-like material formed from fibers and bonded between the fibers. The fiber sheet is preferably a fiber sheet with less fuzz or high surface smoothness so that the short fiber entanglement layer can be easily separated in a subsequent step. Further, it is desirable that the tensile strength is high so as not to cut during conveyance, and a fiber sheet having a wet tensile strength of 5 N / 5 cm width or more, preferably 10 N / 5 cm width or more is desirable. The tensile strength when wet is measured with the fiber sheet containing water of the same weight as its own weight (100% pickup). If the fiber sheet does not have sufficient water retention capacity, the fiber sheet will reach its limit. Measured with water included. The tensile strength is measured with a test piece width of 5 cm according to JISL-1096 General Textile Test Method 8.12.1, Method A.

  The structure of such a fiber sheet is preferably a woven fabric, a knitted fabric, a non-woven fabric, and the like, and the fiber constituting the fiber sheet can be a synthetic fiber, a recycled fiber, or a natural fiber. In addition, if the fiber sheet is a knitted or knitted fabric composed of monofilaments and multifilaments, it can be suitably used because of its high surface smoothness and excellent strength, and is particularly suitable when the fiber sheet is reused. In addition, if the fiber sheet is a non-woven fabric, it is relatively inexpensive and therefore suitable for the case where it is disposable without being reused.

Surface density of the fiber sheet should be 5 to 100 g / m ^2, preferably a 5 to 50 g / m ^2, more preferably from 7~30g / m ^2. If it is less than 5 g / m ² , the fiber structure is coarse and the tensile strength also decreases, so that a large number of short fibers that have passed through the fiber sheet may be entangled with the papermaking net. Moreover, it becomes difficult to separate the fiber sheet from the laminate described later. If it exceeds 100 g / m ² , the papermaking speed will be slow, and a nonwoven fabric with high surface density will not be obtained.

  When a non-woven fabric is used as the fiber sheet, it is desirable that the non-woven fabric has little fuzz or high surface smoothness. For example, a nonwoven fabric having a high surface smoothness on at least one side, preferably obtained by a production method such as passing a web containing thermoplastic fibers between two heating rolls having a smooth surface on at least one roll, is preferable. A non-woven fabric bonded in the form of dots is preferred. Such nonwoven fabrics include dry method nonwoven fabrics composed of staple fibers, spunbond nonwoven fabrics composed of long fibers, and wet nonwoven fabrics. Among them, long fiber nonwoven fabrics such as spunbond nonwoven fabrics have a tensile strength even if the surface density is low. And can be suitably used in the production method of the present invention. The thickness of the nonwoven fabric is preferably 0.05 to 1 mm, more preferably 0.1 to 0.5 mm. Moreover, 10-80 micrometers is preferable and, as for the average fiber diameter of the fiber which comprises a nonwoven fabric, 10-50 micrometers is more preferable. If it exceeds 80 μm, the fiber structure is coarse, and many short fibers may be entangled with the papermaking net. Moreover, when separating the said fiber sheet from the laminated body mentioned later, it may become difficult to isolate | separate. If it is less than 10 μm, the fiber structure may be too dense and the paper making speed may be slow, or the surface density of the nonwoven fabric produced by the present invention may not be increased.

In the production method of the present invention, the fiber sheet is first placed on a papermaking net. As a method of placing, for example, before introducing the papermaking net into the papermaking section of the papermaking machine, there is a method of introducing it so as to overlap the papermaking net. Hereinafter, it demonstrates using FIG. 1 explaining an example of the manufacturing method of this invention. In the figure, a paper machine net 1, a papermaking portion 2, a fiber sheet 3, a roll-like fiber sheet (unwinding portion) 4, and an entanglement nozzle 7 are shown. First, a fiber sheet 4 wound in a roll shape is prepared, and as shown in FIG. Introduce one over the other.

  In the production method of the present invention, the short fiber layer 5 is formed on the fiber sheet 3 by paper-making the short fiber on the fiber sheet 3. As the short fiber, for example, a fiber cut to a fiber length of 1 to 20 mm is dispersed in white water and used. In addition, in the case of an ultrafine short fiber whose fiber diameter is thinner than 8 μm, the fiber length is preferably 1 to 10 mm, and more preferably 1 to 7 mm.

  The short fibers are not limited to synthetic fibers such as PES, PA, polyolefin, acrylic, PVA, and synthetic pulp, but semi-synthetic fibers such as rayon, and natural fibers such as cotton and pulp fibers can be used. Moreover, these fibers can also be mixed and used. In particular, in order to obtain a non-woven fabric having high density, excellent flexibility, and soft texture, the mixing ratio of the synthetic fibers is preferably 50% by mass or more, more preferably 80% by mass or more, and more preferably 95% by mass or more. Moreover, in order to improve the tensile strength of the nonwoven fabric obtained by this invention, it is also possible to mix a heat bondable fiber as a short fiber. In order to easily separate the fiber sheet and the short fiber entangled layer, the mixing ratio of the heat-adhesive fibers is preferably 3 to 15% of the total mass of the short fibers, and more preferably 3 to 10%. preferable.

  According to the production method of the present invention, a nonwoven fabric can be smoothly formed by minimizing the entanglement of the papermaking net by the fiber sheet even in the case of short fibers that have been easily entangled in the papermaking net and difficult to transfer to the entanglement support. There is an advantageous feature of being able to. For example, short fibers with a fiber length of 7 mm or less, ultrafine fibers with a fiber diameter of 0.5 to 8 μm, and sea-island type composite fibers are dissolved and removed, or fibrillated. 2 and a composite fiber whose cross section is illustrated in FIG. 2 is dispersed into, for example, white water so as to be divided into a resin component 8 and a resin component 9, and a modified cross-section fiber having a non-circular fiber cross section. There is. Since webs made of these short fibers have low strength when wet, they can be efficiently produced by being reinforced with fiber sheets.

  The average fiber diameter of the short fibers can be 0.1 to 100 μm, but the present invention is particularly effective for ultrafine fibers having an average fiber diameter of 0.5 to 8 μm. Note that the fiber diameter of a fiber having an atypical cross section, such as an ultrafine fiber that is divided and has a flat cross section, is the value of the diameter of a circle having the same cross sectional area.

  In the present invention, a water flow is then jetted from the short fiber layer 5 side to form a laminate composed of the short fiber entangled layer and the fiber sheet. The jet of water can be performed from the short fiber layer 5 side on the papermaking network 1, but after the short fiber layer 5 is transferred together with the fiber sheet 3 to another entanglement support (not shown). It is also possible to inject a water flow from the short fiber layer 5 side. When the water stream is jetted on the papermaking net 1, there is an advantageous effect that the manufacturing apparatus is simplified and the trouble is reduced accordingly.

  In the method of injecting a water flow from the short fiber layer 5 side, the water flow is injected toward the short fiber layer from one or a plurality of nozzles 7 arranged to face the surface of the short fiber layer. In the nozzle 7, nozzle holes are arranged in one or a plurality of rows, and the nozzles 7 are arranged in a direction in which the row of nozzle holes intersects the production direction. The diameter of the nozzle hole is preferably 0.05 to 0.5 mm, and more preferably 0.1 to 0.2 mm. Moreover, 0.2-5 mm is preferable and the space | interval of adjacent nozzle holes has more preferable 0.3-2 mm. The shape of the water flow ejected from the nozzle 7 is preferably a columnar flow, but the expanding angle may be about 5 to 10 degrees even when the thickness of the water flow increases as the distance from the nozzle hole increases. Further, the pressure in the nozzle 7 is not particularly limited as long as the fiber sheet 3 can be separated from the laminated body in a later step, and within a range in which the short fiber layer 5 can be entangled. -15 MPa, more preferably 1-10 MPa. In the present invention, by selecting an appropriate fiber sheet 3, a high pressure of 2 MPa or more, 4 MPa or more, or 6 MPa or more is possible. It is also possible to arrange a plurality of the nozzles 7.

  Thus, by spraying a water flow from the short fiber layer 5 side, in the short fiber layer 5, the short fibers are entangled with each other to form a short fiber entangled layer 5a. At the same time, a part of the short fibers contained in the short fiber entangled layer 5a penetrates into the gap between the fiber sheets 3, or the gap between the fiber sheet 3 and the short fiber entangled layer 5a is separable. The laminated body which is integrated by force and includes the fiber sheet 3 and the short fiber entanglement layer 5a is formed.

  In the case where a water stream is jetted onto the papermaking net to form a laminated body, the laminated body is peeled off from the papermaking net 1. Since this laminated body is reinforced by the fiber sheet 3, it does not break even if the tensile force of the transfer conveyor 6 is strong, and it is easily peeled off because there is no entanglement between the papermaking net 1 and the short fibers, Can be transported. As the transfer conveyor 6, for example, a known net-like conveyor can be used. Of course, when the papermaking net 1 and the transfer conveyor 6 are in contact with each other, even if the papermaking net 1 and the transfer conveyor 6 are slightly separated, Separation and transfer from the papermaking net 1 are possible by using the fiber sheet 3 that is difficult to stretch.

  Next, the said fiber sheet 3 is isolate | separated from the said laminated body, and the nonwoven fabric which consists of the said short fiber entanglement layer 5a of a dry state or a wet state is manufactured. As a method for separating, there is a method in which the laminate is separated in a wet state or separated after the laminate is dried.

  In order to separate the fiber sheet 3 while the laminate is in a wet state, for example, the laminate is placed on the breathable transfer conveyor 6 so that the fiber sheet 3 is in contact with the laminate, and another ventilation is performed from above the laminate. There is a method of sucking the short fiber layer 5 in a wet state by suction from the opposite surface of the other conveyor while contacting a sex conveyor.

  In the method of separating the fiber sheet 3 after drying the laminated body, as a drying method, for example, a method of introducing the laminated body into a dryer in a state where the laminated body is transferred to the transfer conveyor 6 and the like, and drying by blowing hot air, Alternatively, there is a method in which the laminate is transferred from the transfer conveyor 6 to an air-through dryer and dried. According to the method of separating the fiber sheet 3 after drying the laminate, the short fiber entanglement is performed during the drying process or until the process proceeds to a process for further increasing the strength of the nonwoven fabric composed of the short fiber entangled layer 5a. There is an effect of reinforcing or protecting the layer. Moreover, it is also preferable to peel and isolate | separate the said fiber sheet 3 from the said laminated body by the thermal contraction of the said fiber sheet 3 and / or the said short fiber entanglement layer 5a. It is efficient to perform thermal shrinkage in accordance with the drying of the laminate.

  The nonwoven fabric composed of the short fiber entangled layer 5a separated in the wet state can then be dried to form a nonwoven fabric composed of the short fiber entangled layer 5a in the dry state. In addition, when it is necessary to improve the strength of the nonwoven fabric composed of the short fiber entangled layer 5a, the wet or dry nonwoven fabric composed of the separated short fiber entangled layer 5a is further bonded with fiber, for example, by jetting water flow. It can be set as the nonwoven fabric which improved the intensity | strength by entanglement, resin impregnation, etc.

The surface density of the nonwoven fabric obtained by the present invention is preferably 5 to 200 g / m ² , more preferably 10 to 100 g / m ² , and still more preferably 20 to 100 g / m ² . If it is less than 5 g / m ² , it may be difficult to separate the fiber sheet 3 from the laminate, and if it exceeds 200 g / m ² , the papermaking speed may be too slow.

  Examples of the present invention will be described below, but these are only suitable examples for facilitating understanding of the invention, and the present invention is not limited to the contents of these examples.

Example 1
A spunbonded nonwoven fabric made of polypropylene fibers having a surface density of 15 g / m ² as roll-shaped fiber sheet 4 (thickness 0.15 mm, average fiber diameter 19 μm, tensile strength when wet is 33 N / 5 cm wide, and the horizontal direction is 6N / 5 cm width, the fibers are bonded in the form of dots).

  As shown in FIG. 1, the paper sheet 1 is introduced into the paper making part 2 of the paper machine, and the fiber sheet 3 is introduced while being unwound from the roll 4, and the fiber sheet 3 is placed on the paper machine 1. Thereafter, a slurry in which 0.1 dtex polyester fiber (fiber diameter: 3 μm, fiber length: 3 mm) was dispersed as white fibers in white water was formed, and the short fiber layer 5 was formed on the fiber sheet 3.

  Next, using the nozzle 7 in which the hole diameter is 0.13 mm, the hole interval is 0.6 mm, and the nozzle holes are linearly arranged, from above the short fiber layer 5 toward the short fiber layer, the internal pressure of the nozzle is 3 MPa. A columnar water stream was jetted. As a result, the short fiber entangled layer 5a is formed, and at the same time, a part of the short fibers in the short fiber entangled layer 5a penetrates the gap between the fiber sheets and the short fiber entangled layer 5a and the fiber sheet 3 A laminate was formed.

Next, the laminate was peeled off from the papermaking net 1 and transferred to the transfer conveyor 6, and further introduced into an air-through dryer (not shown) and dried at 140 ° C. Subsequently, the fiber sheet 3 was peeled from the laminate, and a nonwoven fabric composed of the short fiber entangled layer 5a having a surface density of 70 g / m ² could be obtained. In addition, the entanglement of the short fiber to the papermaking net 1 was not recognized.
(Example 2)
A spunbonded nonwoven fabric made of polypropylene fibers having a surface density of 15 g / m ² as roll-shaped fiber sheet 4 (thickness 0.15 mm, average fiber diameter 19 μm, tensile strength when wet is 33 N / 5 cm wide, and the horizontal direction is 6N / 5 cm width, the fibers are bonded in the form of dots).

  As shown in FIG. 1, the paper sheet net 1 is introduced into the paper making part 2 of the paper machine, and the fiber sheet 3 is introduced while being unwound from the roll 4, and the fiber sheet 3 is placed on the paper net 1. Thereafter, 3.3 dtex composite fiber (fiber diameter 18.4 μm, fiber length 5 mm, resin component 8 is a polyester resin, and resin component 9 is a short fiber having a cross-sectional shape as shown in FIG. A slurry in which a polyamide resin) is dispersed in white water is made, and a short fiber layer 5 is formed on the fiber sheet 3. In addition, when the said composite fiber is disperse | distributed in water and it is set as a slurry, one fiber is divided into 11 and each divided | segmented fiber (average fiber diameter of 5.5 micrometers) is an ultrafine with a flat cross section. It was a fiber.

  Next, using a nozzle in which the hole diameter is 0.13 mm and the hole interval is 0.6 mm and the nozzle holes are arranged in a straight line, a columnar shape is formed from above the short fiber layer 5 toward the short fiber layer at a nozzle internal pressure of 4 MPa. A water stream was jetted. As a result, a short fiber entangled layer is formed, and at the same time, a part of the short fibers in the short fiber entangled layer penetrates the gap between the fiber sheets and is composed of the short fiber entangled layer 5a and the fiber sheet 3. The body was formed.

Next, the laminate was peeled off from the papermaking net 1 and transferred to the transfer conveyor 6, and further introduced into an air-through dryer (not shown) and dried at 140 ° C. Subsequently, the fiber sheet 3 was peeled from the laminate, and a nonwoven fabric composed of the short fiber entangled layer 5a having an area density of 65 g / m ² could be obtained. In addition, the entanglement of the short fiber to the papermaking net 1 was not recognized.

The figure explaining an example of the manufacturing method of this invention. (A) The example of the cross section of the short fiber used by this invention. (B) The example of the cross section of the short fiber used by this invention.

Explanation of symbols

1. Papermaking network2. Paper making part3. Fiber sheet 4. 4. Roll-shaped fiber sheet Short fiber layer 5a. 5. Short fiber entanglement layer 6. Transfer conveyor 7. Entanglement nozzle Resin component9. Other resin components

Claims (5)

A fiber sheet made of a non-woven fabric having a surface density of 5 to 100 g / m ² , an average fiber diameter of 10 to 80 μm, and a tensile strength when wet of 5 N / 5 cm or more is placed on a paper machine net , and short fibers Paper is made in a slurry to form a short fiber layer on the fiber sheet, and then a water stream is jetted from the short fiber layer side to form a short fiber entangled layer and the fiber sheet. After making a laminated body, the said fiber sheet is isolate | separated from the said laminated body, and the nonwoven fabric which consists of the said short fiber entanglement layer is manufactured, The manufacturing method of the nonwoven fabric characterized by the above-mentioned.   The method for producing a nonwoven fabric according to claim 1, wherein the jet of water is carried out on a net of the paper machine.   The method for producing a nonwoven fabric according to claim 1, wherein the fiber sheet is separated from the laminate after the laminate is dried.   The method for producing a nonwoven fabric according to any one of claims 1 to 3, wherein the fiber sheet is separated from the laminate by heat shrinkage of the fiber sheet and / or the short fiber entanglement layer.   The said fiber sheet is a long-fiber nonwoven fabric, The manufacturing method of the nonwoven fabric in any one of Claims 1-4 characterized by the above-mentioned.

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