JP7652591B2 - Composite nonwoven fabric manufacturing equipment - Google Patents

Description

The present invention relates to an apparatus for producing a composite nonwoven fabric obtained by hydroentangling a pulp fiber web and a spunbond nonwoven fabric.

Composite nonwoven fabrics made from pulp fiber webs and spunbond nonwoven fabrics have both the absorbency of pulp fibers and the strength of spunbond nonwoven fabrics, and are therefore widely used in a variety of applications, including industrial wipers such as rags, and personal wipers such as hand towels and towels.

For example, as disclosed in Patent Document 1, a pulp fiber web and a spunbond nonwoven fabric are layered and then integrated by a hydroentanglement process in which a high-pressure water jet (water flow) is sprayed onto them. Here, the spunbond nonwoven fabric has excellent strength and functions as a backing layer for the composite nonwoven fabric produced. Meanwhile, the pulp fiber web has excellent liquid absorption properties. Therefore, such a composite nonwoven fabric can be offered to consumers as an excellent composite nonwoven fabric that combines the advantages of a pulp fiber web that has good absorbency for both aqueous and oil-based liquids and a spunbond nonwoven fabric that has excellent strength.

Patent No. 2533260

As described above, when a pulp fiber web is supplied onto a spunbonded nonwoven fabric in a dry or wet manner and then subjected to a hydroentanglement treatment, the pulp fibers on the spunbonded nonwoven fabric are oriented in various directions (three-dimensional random) due to the influence of the water flow. Then, the fabric is dried to become a composite nonwoven fabric as a product. In such composite nonwoven fabrics, it is often found that some of the pulp fibers aligned in the thickness direction are protruding. The fibers aligned in the thickness direction are directly dried to be formed into a bulky fabric. Such a bulky nonwoven fabric is used in either a dry or wet state, and it has been confirmed that the protruding fibers are partially worn away and fall off as fine paper powder (fine pulp fibers). Such a nonwoven fabric has poor value as a product.
However, up to now, no technology has been established that can effectively suppress the generation of paper dust.

Therefore, the object of the present invention is to provide an apparatus capable of producing a composite nonwoven fabric that suppresses the generation of paper dust regardless of whether it is used in a dry or wet state.

The above-mentioned object is to provide a manufacturing device for manufacturing a composite nonwoven fabric in which a pulp fiber web is laminated and integrated onto a spunbond nonwoven fabric, the device comprising a pulp airlaid section which defibrates raw pulp in a dry state, disperses it in an air flow, and supplies the pulp fibers to the lamination position, a spunbond nonwoven fabric supply section which supplies a spunbond nonwoven fabric prepared in advance to the lamination position, and a stacking section which is disposed opposite the lamination position and applies a negative pressure to the spunbond nonwoven fabric and the pulp fiber web placed on the spunbond nonwoven fabric to form a preliminary laminate. This can be achieved by a composite nonwoven fabric manufacturing device that has a layer forming section, a hydroentanglement section downstream of the layer forming section that sprays a water jet toward the pulp fiber web located on the upper side of the preliminary laminate to perform hydroentanglement processing and promote integration of the pulp fiber web and the spunbond nonwoven fabric, a wet press section downstream of the hydroentanglement section that presses the integrated laminate in a wet state, and a drying section that dries the laminate after the pressing to promote interfiber bonding of the pulp fiber web.

The device may further include a dehydration section between the hydroentanglement section and the drying section, which sucks and removes excess water remaining around the laminate.

It is also preferable that the moisture content of the laminate at the inlet side of the drying section or the dehydration section is 60 to 75%.

The wet press section preferably includes a lower press roll and an upper press roll that is placed on the lower press roll in a pressurized state, and the roll equivalent diameter calculated by the formula (roll equivalent diameter) = (upper press roll diameter) x (lower press roll diameter) / {(upper press roll diameter) + (lower press roll diameter)} is 75 to 300 mm.

It is preferable that the conveying speed of the wet press section is set to 100 to 280 m/min, the gap between the rolls is set to 0 to 0.3 mm, and the roll nip pressure is set to 1.0 to 8.0 MPa.

The composite nonwoven fabric manufacturing device of the present invention can efficiently manufacture composite nonwoven fabric with reduced generation of paper dust.

FIG. 2 is a diagram showing a manufacturing apparatus for a composite nonwoven fabric according to the present invention.

An apparatus for producing a composite nonwoven fabric according to one embodiment of the present invention will now be described.
The inventors of the present application have conducted extensive research into composite nonwoven fabrics and have discovered that a composite nonwoven fabric in which the generation of paper dust is suppressed can be obtained by subjecting a wet laminate immediately after it has been subjected to a hydroentanglement process to integrate a pulp fiber web and a spunbond nonwoven fabric, and then by drying the laminate. This discovery led to the present invention.

The composite nonwoven fabric manufacturing apparatus of the present invention will be described below with reference to the drawings. The composite nonwoven fabric manufacturing apparatus of the present invention includes a wet press device as a wet press section that presses the laminate in a wet state after hydroentanglement. First, the main components of the composite nonwoven fabric manufacturing apparatus will be described, and then the wet press device of the present invention will be described in detail.

1 is provided with an airlaid device 2 as a pulp airlaid section on the upstream side, a spunbond supply device 3 as a spunbond nonwoven fabric supply section that supplies spunbond nonwoven fabric, and a suction device 4 as a layer forming section. The suction device 4 is disposed below the airlaid device 2 so as to face it.
In the web transport direction TD, downstream of these devices 2, 3, and 4, there are arranged, in this order from the upstream side, a hydroentangling device 5 as a hydroentangling section which sprays water jets for hydroentangling treatment, a suction device 6 as a dewatering section, and a drying device 7 as a drying section. Downstream of the drying device 7, there is further provided a winding device 8 for winding up the continuously produced composite nonwoven fabric WP.

The airlaid device 2 includes a defibrator 21 that defibrates the raw pulp RP, which is a sheet-like material made of densely packed fibers, into pulp fibers, and a duct 22 that is equipped with a blower (not shown) and transports the defibrated pulp fibers PF to an airlaid hopper 23.

In addition, an airlaid hopper 23 is disposed downstream of the duct 22. Inside this airlaid hopper 23, the pulp fibers in a defibrated state descend while being dispersed, and are designed to gradually pile up at a stacking position 24 set on the lower surface to form a pulp fiber web PFW.
A suction device 4 is disposed below and facing the stacking position 24. More specifically, the suction device 4 has a suction section 42 on the upper surface of an apparatus main body 41, and the suction section 42 is set with respect to the stacking position 24 so as to apply a suction force (negative pressure) to the pulp fiber web PFW.
1 illustrates an example in which the pulp fiber web PFW is formed by arranging the airlaid hopper 23 and the suction device main body 41 in a single stage. However, the present invention is not limited to this, and the airlaid hopper 23 and the suction device main body 41 may be arranged in two or more stages depending on the basis weight (basis weight) and production speed of the pulp fiber web PFW.

A transport wire 43 for transporting the web is disposed around the suction device 4. The transport wire 43 is disposed so that the pulp fiber web PFW on which the pulp fibers PF are accumulated at the stacking position 24 can be placed and transports the web downstream. However, the pulp fiber web PFW is not placed directly on the transport wire 43. This will become clear in the description below.
The conveying wire 43 is formed in an open mesh shape so that the suction force of the suction portion 42 extends to the opposite side (upper side).

A spunbond supplying device 3 is disposed below the airlaid device 2 and upstream of the suction device 4. A roll of spunbond nonwoven fabric SW is set in the spunbond supplying device 3. The spunbond nonwoven fabric SW is pulled out from the spunbond supplying device 3 and transported to the stacking position 24 on the transport wire 43 described above. As the spunbond nonwoven fabric SW, it is preferable to use a web of continuous filaments of synthetic resin formed by the spunbonding method.

The aforementioned pulp fiber web PFW is placed on top of the spunbond nonwoven fabric SW located at the stacking position 24. At this time, the suction force from the suction section 42 of the suction device 4 passes through the conveying wire 43 at the stacking position 24 and acts on the spunbond nonwoven fabric SW and pulp fiber web PFW above it. Therefore, the preliminary laminate PWeb, in which the spunbond nonwoven fabric SW and the pulp fiber web PFW are stacked, is conveyed downstream.

The above-mentioned preliminary laminate PWeb is maintained in a laminated state by being sucked and compressed by the suction force of the suction device 4. At this time, the fibers of the upper pulp fiber web PFW are in a dense state. However, if the preliminary laminate PWeb is transported and fed into the downstream hydroentangling device 5 in this state, there is a risk that a part of the pulp fibers PF will be blown up by the water jet (high-pressure water flow).
Therefore, in the present manufacturing apparatus 1, there are provided a clamping roller 28 for sandwiching the preliminary laminate PWeb from above and below to stabilize the placement state of the pulp fiber web PFW on the spunbond nonwoven fabric SW, and a pre-wetting device 30 for applying moisture to prevent the fibers from scattering upstream of the hydroentangling device 5. The pre-wetting device 30 preferably includes a spray nozzle 31 for spraying water mist from above the preliminary laminate PWeb, and a suction device 32 for applying suction force from the underside of the preliminary laminate PWeb (i.e., the underside of the pulp fiber web PFW).
1 shows an example in which the pre-wetting device 30 is provided as a new device before the hydroentanglement device 5 as described above, but the present invention is not limited to this. The design of the hydroentanglement device 5 may be modified so that the first set of a plurality of sets each consisting of a water jet head 51 and a suction device 52 (described later) is used as the pre-wetting device 30. In this case, adjustments may be made so that low-pressure water mist is sprayed from the first water jet head 51.
In the case of a hydroentanglement device 5 that has a sufficient number of sets of water jet heads 51 and suction devices 52 to perform hydroentanglement processing, using the leading water jet head 51 and suction device 52 as a pre-wetting device as described above is effective in reducing equipment costs.

Then, in the hydroentangling device 5, entangling of the pulp fibers is promoted by spraying a high-pressure water jet onto the preliminary laminate PWeb that has been treated by the pinch rollers 28 and the pre-wetting device 30, which are the pre-treatment section, thereby promoting integration of the pulp fiber web PFW layer located on the upper side and the spunbond nonwoven fabric SW layer located on the lower side.
The hydroentangling device 5 exemplarily shown in FIG. 1 has water jet heads 51 arranged in multiple stages (four stages are shown as an example in FIG. 1) along the conveyance direction TD.
1 does not show the nozzles provided on the water jet head 51 extending in a direction perpendicular to the transport direction TD (the width direction of the web), but a plurality of water jet nozzles are arranged at appropriate positions in the width direction. The hole diameter φ of the water jet nozzles is preferably 0.06 to 0.15 mm. The interval between the water jet nozzles is preferably 0.4 to 1.0 mm.

The water pressure during the hydroentanglement process is desirably set taking into consideration the basis weights of the pulp fiber web PFW and the spunbond web SW. For example, it is preferable to select a pressure in the range of 1 to 30 MPa.

A suction device 52 is disposed opposite the water jet head 51. A high-pressure water jet from the water jet head 51 is sprayed onto the pulp fiber web PFW located on the upper side, while the suction force of the suction device 52 is applied to the underside of the spunbond nonwoven fabric SW located on the lower side. It is presumed that the cooperative action of the water jet head 51 and the suction device 52 creates a state in which the pulp fibers on the pulp fiber web PFW side penetrate into the spunbond nonwoven fabric SW located on the lower side, or penetrate the spunbond nonwoven fabric SW to reach the other side. This action promotes the integration of the two layers.

The hydroentangling device 5 is also provided with a conveying wire 55. The conveying wire 55 receives the preliminary laminate PWeb downstream of the pre-treatment units 28 and 30, and conveys it into the hydroentangling device 5. The conveying wire 55 is disposed so as to pass between the water jet head 51 and the suction device 52 of the hydroentangling device 5 from the upstream side to the downstream side.
Therefore, the preliminary laminate PWeb transported on the transport wire 55 undergoes more hydroentanglement treatment as it moves downstream in the transport direction TD, and by the time it leaves the hydroentanglement device 5, sufficient entanglement treatment is achieved between the upper pulp fiber web layer PFW and the lower spunbond nonwoven fabric SW layer.
Immediately after leaving the hydroentangling device 5, the nonwoven fabric is in a wet state, and the bonds between the pulp fibers etc. are not yet sufficiently established.

1, a suction device 6 and a drying device 7 are provided downstream of the hydroentanglement device 5 to suck and remove the water remaining in the web, and then to dry the web and complete the production of the composite nonwoven fabric WP. By performing dehydration and drying using the suction device 6 and the drying device 7 in this manner in the latter stages of the production of the composite nonwoven fabric WP, the nonwoven fabric can be produced efficiently.
The suction device 6 is, for example, a vacuum type, and dehydrates the nonwoven fabric after the water flow entanglement. The drying device 7 is preferably a non-compression type dryer, preferably an air-through dryer. In Fig. 1, the rotatable dryer body 71 of the air-through dryer is a cylindrical body, and a number of through holes are provided on its peripheral surface, and it is preferable that hot air heated by a heat source (not shown) is sucked from the outer periphery of the dryer body toward the center.
The composite nonwoven fabric WP thus continuously produced is wound around the roller 81 of the winding device 8, completing the series of steps.

The above steps allow conventional composite nonwoven fabrics to be manufactured, but the composite nonwoven fabric manufacturing apparatus of the present invention is equipped with a wet press device 9 that applies a press (pressurization) treatment to the laminate in a wet state after hydroentangling by the hydroentangling device 5.

1, the wet press device 9 is disposed immediately after the hydroentanglement device 5 and before the suction device 6, and includes an upper press roll 9a and a lower press roll 9b that contact the pulp fiber web PFW side. The upper press roll 9a contacts the pulp fiber web PFW, and the lower press roll 9b contacts the spunbond nonwoven fabric SW layer.
The upper press roll and the lower press roll are desirably designed so that the roll equivalent diameter calculated by the formula (roll equivalent diameter) = (upper press roll diameter) x (lower press roll diameter) / {(upper press roll diameter) + (lower press roll diameter)} is 75 to 300 mm, more preferably 100 to 250 mm. The roll equivalent diameter here is based on the literature presented by AV Lyons et al. (1990 TAPPI Finishing and Converting, p. 5).
The roll equivalent diameter can be used as an index of the smoothing effect of fibers protruding from the pulp fiber web PFW (hereinafter simply referred to as the pulp fiber web) in the composite nonwoven fabric WP. For example, if the roll equivalent diameter is less than 75 mm, the force applied to the surface is too small, so the smoothing effect of the protruding pulp fibers is small, and the paper dust suppression effect is small.
On the other hand, if the roll equivalent diameter is greater than 300 mm, the surface of the composite nonwoven fabric on the pulp fiber web side becomes hardened.

Furthermore, the roll nip pressure between the upper press roll 9a and the lower press roll 9b is preferably set to 1.0 to 8.0 MPa, the gap between the rolls is preferably set to 0 to 0.3 mm, and the roll conveying speed is preferably set to 100 to 280 m/min, more preferably 150 to 250 m/min.
By setting the operating conditions of the wet press device 9 within the above ranges, the fibers protruding from the pulp surface of the composite nonwoven fabric are smoothed out, and the generation of paper dust during use of the composite nonwoven fabric can be reliably suppressed.
Furthermore, if the conveying speed is too fast, the gap between the rolls is too wide, or the roll nip pressure is too low compared to the above-mentioned ranges, the effect of suppressing fiber protrusion from the pulp fiber web will be weakened, and as a result, the effect of suppressing paper dust will be reduced (more paper dust will be produced during use).
Conversely, if the conveying speed is too slow or the roll nip pressure is too high, too much force acts on the composite nonwoven fabric, hardening the surface of the pulp fiber web, reducing the thickness and increasing the density. Such a composite nonwoven fabric has a slow water absorption speed and a low total water absorbency (T.W.A.), resulting in a hard, paper-like feel. This composite nonwoven fabric provides a poor wiper feel.
Although there are no particular limitations on the material of the upper press roll 9a and the lower press roll 9b, it is preferable to use metal rolls for both.

1 shows an example in which the wet press unit 9 is disposed before the suction unit (dewatering unit) 6, but the wet press unit 9 may be disposed between the suction unit 6 and the dryer 7. In this latter case, the suction unit 6 may be designed to suck in enough water to remove excess water remaining around the laminate WP, and the pulp fiber web PFW in a wet state may then be dried in the dryer 7.
It is preferable to adjust the wet press device 9 so that the moisture content of the laminate WP before dehydration or drying at the inlet side of the suction device 6 immediately after the wet press device 9, or at the inlet side of the drying device 7 immediately after the wet press device 9, is 60 to 75%.
In the present invention, the moisture content is the same as the moisture percentage, and is calculated by the following formula: moisture content (moisture percentage) (%)=(weight of composite nonwoven fabric (measured at the inlet side of the suction device 6 or the drying device 7)-weight of composite nonwoven fabric (bone dry))÷weight of composite nonwoven fabric (bone dry)÷100.
In the composite nonwoven fabric manufacturing apparatus according to the present invention, a wet press process is performed after hydroentanglement, so that the fibers protruding from the surface are laid flat and smoothed. As described above, in the pulp fiber web PFW in a wet state, the bonds (hydrogen bonds) between the pulp fibers are not firmly established and the bonds are loose. In this state, the protruding fibers are smoothed by the wet press device 9, and then the smoothed state is maintained by quickly performing a dehydration and drying process or a drying process, and a smooth and high-density pulp fiber web PFW can be formed. This makes it possible to obtain a composite nonwoven fabric that suppresses the generation of paper dust.
By the way, one method that has been considered to increase the bonds between pulp fibers is to use a press roll treatment after the drying process. However, although this increases the density of the surface, the dry state does not promote hydrogen bonding, and the generation of paper powder during use was not improved.

In the above-mentioned composite nonwoven fabric manufacturing apparatus 1, mechanical dehydration is performed in advance by the wet press device 9, which improves unevenness in the drying process performed downstream, reduces the drying load, and further reduces dirt that adheres to the dryer of the drying device 7, which is expected to reduce cleaning work.
Furthermore, the manufacturing apparatus 1 employs a dry airlaid method to obtain a pulp fiber web. Pulp fiber webs can also be manufactured by utilizing conventional wet papermaking methods, but wet equipment that utilizes papermaking technology is large and requires laborious management, resulting in high costs. In contrast, the airlaid apparatus, as described above, can be incorporated as part of a composite nonwoven fabric manufacturing apparatus, and is simpler than wet equipment, lower cost, and easier to manage, so composite nonwoven fabrics can be manufactured efficiently at reduced costs.

In the manufacturing apparatus 1, it is preferable to adopt a composite nonwoven fabric that satisfies the following conditions. It is preferable that the basis weight of the pulp fiber web is 40.0 to 83.0 g/ ^m2 , and the weight composition ratio of the spunbond nonwoven fabric to the pulp fiber web is 40/60 to 10/90 (wt%). A composite nonwoven fabric in this range has excellent water absorption performance and excellent shape stability.
The basis weight of the spunbonded nonwoven fabric is preferably 7.0 to 20.0 g/ ^m2 . The spunbonded nonwoven fabric is formed to include a plurality of fusion points that bond the spun resin fibers, and it is preferable that the area of each fusion point is 0.10 to 0.50 ^mm2 , the area ratio of the fusion points per unit area is 7 to 20%, and the number of fusion points is 10 to 150/ ^cm2 . Such a spunbonded nonwoven fabric has an appropriate rigidity and is suitable as a spunbonded nonwoven fabric to be used in combination with a pulp fiber web to form a composite nonwoven fabric. The shape of the fusion points is not particularly limited and may be circular, elliptical, polygonal, etc.

The spunbond nonwoven fabric is preferably made of one or a mixture of two or more materials selected from the group consisting of nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, and polystyrene. Among these, polypropylene is preferably used.
Furthermore, it is preferable to use the pulp fiber web formed from fibers of bleached kraft pulp of a softwood selected from the group consisting of radiata pine, slash pine, southern pine, lodgepole pine, spruce and Douglas fir.

This concludes the explanation of the embodiment, but it goes without saying that the present invention is not limited to the above embodiment and can be modified in various ways without departing from the spirit of the invention.

LIST OF SYMBOLS 1 Composite nonwoven fabric manufacturing device 2 Airlaid device 3 Spunbond nonwoven fabric supply device 4 Suction device 5 Hydroentanglement device 6 Suction (dewatering) device 7 Drying device 8 Winding device 9 Wet press device 9a Upper press roll 9b Lower press roll 21 Defibrator 22 Duct 23 Airlaid hopper 24 Stacking position 28 Grip roller 30 Pre-wetting device 31 Spray nozzle 32 Suction device 41 Suction device main body 42 Suction section 43 Conveying wire 51 Water jet head 52 Suction device 55 Conveying wire SW Spunbond nonwoven fabric PF Pulp fiber PFW Pulp fiber web PWeb Preliminary laminate (laminated web)
WP Composite nonwoven fabric TD Transport direction

Claims (5)

A manufacturing apparatus for manufacturing a composite nonwoven fabric in which a pulp fiber web is laminated and integrated onto a spunbond nonwoven fabric, comprising:
a pulp airlaid section that defibrates raw pulp in a dry state, disperses it in an air flow, and supplies pulp fibers to a layering position;
a spunbond nonwoven fabric supply unit that supplies a previously prepared spunbond nonwoven fabric to the lamination position;
a lamination forming section disposed opposite to the lamination position and configured to apply a negative pressure to the spunbond nonwoven fabric and the pulp fiber web placed on the spunbond nonwoven fabric to form a preliminary laminate;
a hydroentangling section downstream of the lamination section, which sprays a water jet toward the pulp fiber web located on the upper side of the preliminary laminate to perform a hydroentangling treatment, thereby promoting integration of the pulp fiber web and the spunbond nonwoven fabric;
a wet press section downstream of the hydroentanglement section for pressing the integrated laminate in a wet state;
a drying section for drying the laminate after the pressing to promote inter-fiber bonding of the pulp fiber web ;
The wet press section includes a lower press roll and an upper press roll disposed on the lower press roll in a pressurized state,
The apparatus for producing a composite nonwoven fabric is characterized in that the roll equivalent diameter calculated by the formula (roll equivalent diameter) = (upper press roll diameter) x (lower press roll diameter) / {(upper press roll diameter) + (lower press roll diameter)} is 75 to 300 mm . The composite nonwoven fabric manufacturing apparatus according to claim 1, further comprising a dehydration section between the hydroentanglement section and the drying section, which sucks and removes excess water remaining around the laminate. 3. The apparatus for manufacturing a composite nonwoven fabric according to claim 2 , wherein the moisture content of the laminate at the inlet side of the dewatering section is 60 to 75%. 2. The apparatus for manufacturing a composite nonwoven fabric according to claim 1, wherein the moisture content of the laminate at the inlet side of the drying section is 60 to 75%. The manufacturing apparatus for a composite nonwoven fabric according to any one of claims 1 to 4, characterized in that the conveying speed of the wet press section is set to 100 to 280 m/min, the gap between the rolls is set to 0 to 0.3 mm, and the roll nip pressure is set to 1.0 to 8.0 MPa.

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