Composite nonwoven fabric and its manufacturing method

Abstract

To provide a composite nonwoven fabric having required voluminousness and smoothness, and moderate bounce with exfoliation of fiber suppressed.SOLUTION: A composite nonwoven fabric including a spun-bonded nonwoven fabric on which a pulp fiber web is laminated and integrated has a basis weight of 40.0 to 110.0 g / m2, a bulk density of 4.3 to 7.5 cm3 / g, and a TSA (D value) as index of bounce (strength) of 1.0 to 2.5 mm / N.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a composite nonwoven fabric obtained by hydroentangling a pulp fiber web and a spunbond nonwoven fabric. [Background technology]

[0002] A composite nonwoven fabric made of a pulp fiber web and a spunbonded nonwoven fabric has both the liquid absorbency derived from the pulp fibers and the strength derived from the spunbonded nonwoven fabric, and is therefore widely used in a variety of applications, such as industrial wipers such as rags, and personal wipers such as hand towels and towels.

[0003] 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 provided 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. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 2533260 Summary of the Invention [Problem to be solved by the invention]

[0005] Among composite nonwoven fabrics such as those described above, those that have an appropriate sense of volume (mass) that can be felt by the user through bulk and thickness when used, as well as a smooth surface and little fiber shedding are highly rated as products. For example, by subjecting a composite nonwoven fabric to a calendaring process, it is possible to adjust the thickness to any desired value and impart uniformity and smoothness to the surface. However, on the other hand, since the composite nonwoven fabric is pressed and smoothed, the so-called stiffness (a type of strength, the resistance when a bending force is applied to the nonwoven fabric, hereinafter sometimes simply referred to as "stiffness") is reduced. On the other hand, a method of thermal embossing with an embossing roll at a high temperature is known as a method of imparting stiffness to a composite nonwoven fabric. In this treatment, a roll having a plurality of protrusions, which are equivalent to pillars, is used to press the embossing against the surface of the composite nonwoven fabric, while applying heat to the spunbond nonwoven fabric (synthetic resin fiber) side of the composite nonwoven fabric and then curing it, thereby imparting appropriate stiffness. However, on the other hand, it is difficult to adjust the thickness delicately with the thermal embossing process, and problems with the smoothness of the appearance may occur. As described above, the calendaring and heat embossing treatments for composite nonwoven fabrics are in an opposing relationship, and it has been difficult to obtain a composite nonwoven fabric that has the required volume (massiveness) and smoothness, as well as appropriate stiffness and reduced fiber shedding.

[0006] The pulp fiber web of the composite nonwoven fabric can be obtained by utilizing a conventional wet papermaking method or by using a dry airlaid method. When a pulp fiber web made by the dry airlaid method is used, the above-mentioned problems, that is, the difficulty in finely adjusting the thickness during the thermal embossing treatment, and the tendency for problems in the smoothness of the appearance to occur are recognized to be greater. However, in terms of manufacturing equipment and costs, it is preferable to adopt the dry airlaid method rather than the wet papermaking method.

[0007] An object of the present invention is to provide a composite nonwoven fabric which has the required volume and smoothness, as well as appropriate stiffness and which is furthermore inhibited from shedding of fibers. [Means for solving the problem]

[0008] The above object is to provide a composite nonwoven fabric having a pulp fiber web laminated and integrated onto a spunbond nonwoven fabric, the basis weight of which is 40.0 to 110.0 g / m 2 And the volume is 4.3 to 7.5 cm 3 This can be achieved by a composite nonwoven fabric having a stiffness (tensile strength) of 1.0 to 2.5 mm / N and a TSA (D value), which is an index showing stiffness (strength), of 1.0 to 2.5 mm / N.

[0009] And the TSA (TS7 value), which is an index of softness, is 12.0 to 20.0 dBV. 2 TSA (TS750 value), which is an index of rms and smoothness, is 33.0 to 100.0 dBV 2 Preferably, it is rms. Furthermore, the thickness is preferably 0.30 to 0.50 mm.

[0010] The pulp fiber web has a basis weight of 30.0 to 80.0 g / m 2 Moreover, it is preferable that the weight ratio of the spunbond nonwoven fabric to the pulp fiber web is 40 / 60 to 10 / 90 (wt %).

[0011] The basis weight of the spunbond nonwoven fabric is 10.0 to 30.0 g / m 2 The spunbond nonwoven fabric is formed to include a plurality of fusion points that bond the spun resin fibers, and the area of ​​each fusion point is 0.10 to 0.50 mm 2 The area ratio of the fusion points per unit area is 7 to 20%, and the number of the fusion points is 10 to 150 / cm 2 It is preferable that:

[0012] The spunbond nonwoven fabric is desirably formed of one or a mixture of two or more materials selected from the group consisting of nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, and polystyrene.

[0013] Also, the pulp fiber web is preferably comprised of bleached kraft pulp fibers from a softwood selected from the group consisting of radiata pine, slash pine, southern pine, lodgepole pine, spruce and Douglas fir.

[0014] The above object can also be achieved by a method for producing a composite nonwoven fabric in which a pulp fiber web is laminated and integrated onto a spunbonded nonwoven fabric, the method comprising at least a hydroentanglement step of promoting integration of the pulp fiber web and the spunbonded nonwoven fabric to obtain a laminate, and a drying step of drying the laminate after the hydroentanglement step, the method further comprising a calendaring step of passing the laminate between calendar rolls while applying pressure to it after the drying step, and a hot embossing step of applying a hot embossing treatment to the pulp fiber web side after the calendaring step.

[0015] In the calendaring process and / or the heat embossing process, it is preferable to use a main roll and a backing roll having a roll equivalent diameter of 75 to 300 mm calculated by the formula (roll equivalent diameter) = (main roll diameter) x (backing roll diameter) / {(main roll diameter) + (backing roll diameter)}, set the conveying speed to 100 to 300 m / min, the gap between the rolls to 0 to 0.5 mm, and the roll nip pressure to 0.5 to 6.5 MPa. In the hot embossing step, the temperature of the main roll is preferably set to 40 to 200°C. Effect of the Invention

[0016] According to the present invention, a composite nonwoven fabric having the required volume and smoothness, appropriate stiffness, and reduced fiber shedding can be provided. Furthermore, according to the manufacturing method of the present invention, the composite nonwoven fabric can be efficiently manufactured. [Brief description of the drawings]

[0017] [Figure 1] FIG. 2 is a diagram showing a manufacturing apparatus for a composite nonwoven fabric. [Diagram 2] FIG. 2 is a diagram showing a schematic configuration of an embossing device and the appearance of an embossed composite nonwoven fabric. [Diagram 3] These figures are shown to explain the shape of the embossing roll, and Fig. 3(a) or Fig. 3(b) is a cross-sectional view showing an enlarged portion of the surface of the embossing roll, and Fig. 3(c) is a plan view showing an enlarged portion of the surface of the embossing roll. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, a composite nonwoven fabric according to one embodiment of the present invention will be described. The inventors of the present application have conducted extensive research into composite nonwoven fabrics and have found that the basis weight (g / m 2 ) and volume (cm 3 The inventors have confirmed that a composite nonwoven fabric designed so that its TSA (D value), which is an index of stiffness (strength), falls within a predetermined range has the required volume and smoothness, as well as appropriate stiffness and suppressed fiber shedding, leading to the present invention. Such a composite nonwoven fabric can be produced by sequentially carrying out a calendaring process and a heat embossing process after a drying process. Furthermore, the composite nonwoven fabric of the present invention has a softness index, TSA (TS7 value (dBV 2 rms)) and TSA (TS750 value (dBV 2 It is preferable that the thickness (mm) is also designed to be within a specified range. The above factors and their preferred ranges relating to the composite nonwoven fabric will be explained below.

[0019] The basis weight of the composite nonwoven fabric according to the present invention is 40.0 to 110.0 g / m 2 , preferably 62.0 to 77.0 g / m 2 and the bulk is 4.3 to 7.5 g / m 2 , preferably 5.0 to 6.4 g / m 2 , the TSA (D value) is set to 1.0 to 2.5 mm / N. A composite nonwoven fabric formed so that the basis weight, bulk, and TSA (D value) fall within the above ranges has the required volume and smoothness, as well as appropriate stiffness and reduced fiber shedding. Here, the above index TSA (TS7 value) is 12.0 to 20.0 dBV. 2 rms, TSA (TS750 value) is 33.0 to 100.0 dBV 2 The thickness is set to 0.30 to 0.50 mm, preferably 0.35 to 0.45 mm.

[0020] The above D value, TS7 value, and TS750 value are indicated as TSA (D value), TSA (TS7 value), and TSA (TS750 value) to indicate that they were measured using a tissue softness measuring device TSA (Tissue Softness Analyzer). The TSA tissue softness measuring device quantitatively evaluates the softness (hand feel) of nonwoven fabrics and the like by pressing a bladed rotor, for example, with a pressing pressure of 100 mN against a composite nonwoven fabric (sample) placed on a sample stage with the pulp side facing up and rotating at 2.0 / sec., analyzing the vibration data detected by various sensors and parameterizing it (TS value), and the softness (hand feel) of nonwoven fabrics and the like is evaluated. This is the product name of Emtec Electronic GmbH of Germany (Japan distributor is Nippon Luft Co., Ltd.). In measurements using the above-mentioned tissue softness measuring device TSA, for example, the vibration of the sample stage is measured by a vibration sensor installed inside the sample stage, and the vibration frequency is analyzed and parameterized (TS value). The vibration frequency depends on the structural dimensions of creep processing, embossing processing, etc., and the rotation speed of the blade. The induction of horizontal vibration of the blade itself (resonant frequency: for example, 6500 Hz) occurs when the blade advances over the surface of the sample, due to momentary interruption by a convex part of the sample and the vibration of the blade. The intensity of the first maximum peak in the spectrum from the low frequency side is expressed as the TS750 value (dBV 2 rms), and the intensity of the maximum peak in the spectrum including the resonance frequency of 6500 Hz (around 6500 Hz) is the TS7 value (dBV 2 rms). Furthermore, without rotating the bladed rotor, the sample is deformed, for example, with a pressing pressure of 100 mN and 600 mN, and the amount of deformation (mm / N) in the vertical direction is measured as the D value.

[0021] The software for analyzing vibration and parameterizing (TS value) can be the emtec measurement system. This software is equipped with various algorithms (e.g., Base Tissue, Facial, TP, etc.), and the above TS7 value, TS750 value, and D value are automatically obtained on the software, and the HF (hand feel) value is calculated from these TS7 value, TS750 value, and D value or basis weight, thickness, number of plies, etc., depending on the type of various algorithms. In the present invention, the TS7 value, TS750 value, and D value are specified instead of the HF value, and any algorithm can be used as long as the measurement conditions are met, and the TS7 value, TS750 value, and D value do not change depending on the type of algorithm.

[0022] The basis weight of the pulp fiber web is, for example, 30.0 to 80.0 g / m 2 The weight ratio of the spunbond nonwoven fabric to the pulp fiber web is preferably, for example, 40 / 60 to 10 / 90 (wt%). A composite nonwoven fabric in this range has excellent water absorption performance and hand feeling, and has excellent shape stability. The basis weight of the spunbond nonwoven fabric is, for example, 10.0 to 30.0 g / m 2 In addition, the spunbond nonwoven fabric is formed to include a plurality of fusion points that bond the spun resin fibers, and the area of ​​each of the fusion points is preferably 0.10 to 0.50 mm. 2 The area ratio of fusion points per unit area is 7-20%, and the number of fusion points is 10-150 / cm 2 Such a spunbonded nonwoven fabric has an appropriate rigidity and is suitable for use as a spunbonded nonwoven fabric to be combined 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.

[0023] 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 bleached kraft pulp fibers of a softwood selected from the group consisting of radiata pine, slash pine, southern pine, lodgepole pine, spruce and Douglas fir.

[0024] The steps for producing the composite nonwoven fabric of the present invention will be described below. The composite nonwoven fabric of the present invention can be efficiently produced by sequentially carrying out a drying step, a calendaring process, and a hot embossing process. Here, the main components of the production apparatus for producing the composite nonwoven fabric WP will be described, followed by a description of the calendaring device and the embossing device.

[0025] 1, a composite nonwoven fabric manufacturing apparatus 1 is provided with an airlaid device 2 on the upstream side, a spunbond supplying device 3 that supplies a spunbond nonwoven fabric, and a suction device 4. 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 hydroentanglement device 5 that sprays water jets for hydroentanglement treatment, a suction device 6, and a drying device 7. Downstream of the drying device 7, there is further provided a winding device 8 for winding up the composite nonwoven fabric WP that is continuously produced.

[0026] The airlaid apparatus 2 includes a defibrator 21 that defibrates raw pulp RP, which is a sheet-like material in which fibers are densely packed together, 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.

[0027] 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 facing the lower side of 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 shows 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.

[0028] 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 from the explanation given later. 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).

[0029] 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 that has been prepared in advance is set in this spunbond supplying device 3. The spunbond nonwoven fabric SW is pulled out from the spunbond supplying device 3 and transported to the layering 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 a synthetic resin formed by a spunbonding method.

[0030] The above-mentioned pulp fiber web PFW is placed on the spunbond nonwoven fabric SW located at the stacking position 24. At this time, the suction force by 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 the pulp fiber web PFW thereon. Thus, the preliminary laminate PWeb in which the spunbond nonwoven fabric SW and the pulp fiber web PFW are stacked is conveyed downstream.

[0031] The above-mentioned preliminary laminate PWeb is maintained in a laminated state by being suction-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 clamping rollers 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 the hydroentanglement treatment, 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.

[0032] 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 clamping rollers 28 and the pre-wetting device 30, which are the pre-treatment section. This promotes integration of the pulp fiber web PFW layer located on the upper side with 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 in FIG. 1) along the conveyance direction TD. 1 does not show the nozzles provided on the water jet head 51 extending in the direction perpendicular to the conveying direction TD (the width direction of the web), but multiple water jet nozzles are arranged at appropriate positions in the width direction. The hole diameter φ of the water jet nozzle is preferably 0.06 to 0.15 mm. The interval between the water jet nozzles is preferably 0.4 to 1.0 mm.

[0033] The water pressure during the hydroentanglement treatment is desirably set in consideration of the basis weights of the pulp fiber web PFW and the spunbond web SW, and is preferably selected within the range of, for example, 1 to 30 MPa.

[0034] 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 lower side 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 on the lower side, or penetrate through the spunbond nonwoven fabric SW to reach the opposite side. This action promotes integration of the two layers.

[0035] 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 provided 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 PFW layer 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.

[0036] 1, a suction device 6 and a dryer 7 are provided downstream of the hydroentanglement device 5 to remove residual moisture from the web by suction and then dry the web to complete the production of the composite nonwoven fabric WP. By performing dehydration and drying using the suction device 6 and the dryer 7 in this manner at the latter stage of the production of the composite nonwoven fabric WP, the nonwoven fabric can be produced efficiently, and the nonwoven fabric can be dried without applying a large external pressure to the hydroentangled nonwoven fabric, resulting in a finished product with a sense of bulk. The suction device 6 is, for example, a vacuum type, and dehydrates the nonwoven fabric after hydroentanglement. 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 a series of steps.

[0037] In the manufacturing apparatus shown in Figure 1, the pulp fiber web is supplied by a dry airlaid method using the airlaid apparatus 2 described above, so equipment and manufacturing costs can be reduced compared to forming a pulp fiber web by a wet method. On the other hand, as described above, in the case of a composite nonwoven fabric containing a pulp fiber web produced by the airlaid method, it is difficult to adjust the thickness, and there are concerns about the smoothness of the appearance. The composite nonwoven fabric of the present invention eliminates these concerns. This point will be made clear from the following explanation.

[0038] Although a general composite nonwoven fabric can be manufactured by the above steps, the composite nonwoven fabric of the present invention has the necessary volume and smoothness, as well as appropriate stiffness, and furthermore, fiber shedding is suppressed, even when a pulp fiber web produced by the airlaid method is used. For this reason, after the drying step by the drying device 7, as shown in Fig. 1, a calendaring process is performed by a calendaring device CA, and further downstream, a thermal embossing process is performed under predetermined conditions on the pulp fiber web PFW side by an embossing device EA, thereby manufacturing the composite nonwoven fabric of the present invention.

[0039] The calender CA may be of the same configuration as the calenders known to be used in the downstream of paper manufacturing equipment. Although detailed illustration is omitted here, the calender CA is equipped with a pair of metal rolls with smooth surfaces. By passing the composite nonwoven fabric between the metal rolls and applying pressure, the thickness is adjusted and the surface is made smooth.

[0040] The pair of metal rolls are arranged in a horizontal position so as to overlap one above the other, and the dried composite nonwoven fabric passes between them. The upper one is the main roll and the lower one is the receiving roll. The main roll and the backing roll are desirably designed so that the roll equivalent diameter calculated by the formula (roll equivalent diameter) = (main roll diameter) x (backing roll diameter) / {(main roll diameter) + (backing roll diameter)} is 75 to 300 mm, more preferably 100 to 250 mm. The roll equivalent diameter here is based on the literature (1990 TAPPI Finishing and Converting, p. 5) presented by AV Lyons et al., and is an index of the strength of the calendar treatment applied to the composite nonwoven fabric. For example, if the roll equivalent diameter is less than 75 mm, the calendar treatment applied to the composite nonwoven fabric is likely to be insufficient, while if the roll equivalent diameter is greater than 300 mm, the calendar treatment becomes too strong. The roll nip pressure between the main roll and the backing roll is set to 0.5 to 6.5 MPa, more preferably 2.0 to 5.0 MPa. The gap between the rolls is set to 0 to 0.5 mm. The roll transport speed is preferably set to 100 to 300 m / min, more preferably 150 to 250 m / min.

[0041] An embossing device EA is further disposed downstream of the calendering device CA. The embossing device EA is illustrated in Fig. 2. Fig. 2 shows a schematic configuration of the embossing device EA on the left side, and a schematic view of the embossed composite nonwoven fabric WP on the right side. The embossing device EA in Fig. 2 is equipped with an embossing roll a1, which is an upper main roll that contacts the pulp fiber web PFW side, and a plain receiving roll a2 on the lower side. The outer peripheral surface of the embossing roll a1 is engraved with a concave-convex pattern to be formed on the pulp fiber web PFW. On the other hand, the outer peripheral surface of the receiving roll a2 is formed flat. The relationship between the embossing roll a1 and the receiving roll a2 is also set by calculating the above-mentioned roll equivalent diameter. That is, it is desirable to design the roll equivalent diameter calculated by the formula (roll equivalent diameter) = (embossing roll diameter) x (receiving roll diameter) / {(embossing roll diameter) + (receiving roll diameter)} to be 75 to 300 mm, more preferably 100 to 250 mm. The roll equivalent diameter here is an index of the strength of the embossing applied to the composite nonwoven fabric. For example, if the roll equivalent diameter is less than 75 mm, it becomes difficult to emboss the composite nonwoven fabric, while if the roll equivalent diameter is more than 300 mm, the embossing becomes too strong. In addition, problems such as high running costs and large installation space arise due to the equipment.

[0042] The roll nip pressure between the embossing roll a1 and the receiving roll a2 is set to 0.5 to 6.5 MPa, more preferably 2.0 to 5.0 MPa. The gap between the rolls is set to 0 to 0.5 mm, and at least one of the embossing roll a1 and the plain roll a2 is provided with a heating means (e.g., a heater) so that the temperature of the embossing roll a1 is set to 40 to 200° C., more preferably 100 to 150° C. The conveying speed of the rolls is desirably set to 100 to 300 m / min, more preferably 150 to 250 m / min. By setting the embossing operating conditions within the above ranges, the pulp surface of the composite nonwoven fabric after calendaring is appropriately embossed to impart stiffness, and the generation of paper dust when the composite nonwoven fabric is used can also be suppressed. If the force applied to the surface of the composite nonwoven fabric is small because the roll equivalent diameter used in the thermal embossing treatment is too small, the conveying speed is too fast, the gap between the rolls is too large, the roll nip pressure is too low, the temperature is too low, etc., the surface will have small unevenness and will not be hardened by heat, resulting in poor stiffness (strength). On the other hand, if the roll equivalent diameter is too large, the conveying speed is too slow, the roll nip pressure is too high, the temperature is too high, etc., the force applied to the surface of the composite nonwoven fabric will be too large, and the composite nonwoven fabric itself will deteriorate, causing holes in the surface or reducing its strength. The materials for the embossing roll a1 and the receiving roll a2 are not particularly limited, but it is preferable to use metal rolls for both. A suitable uneven pattern can be formed on the pulp fiber web PFW by heat embossing using the embossing device EA set to satisfy the above conditions. The surface of the lower spunbond nonwoven fabric SW (the back side of the composite nonwoven fabric WP) is flattened by contacting the receiving roll a2.

[0043] Furthermore, Fig. 3 is a diagram for explaining the form of an embossing roll preferably used in the embossing device EA. Fig. 3(a) or Fig. 3(b) is a cross-sectional view showing an enlarged portion of the surface fa of the embossing roll a1, and a plurality of embossing projections EP for forming embosses are present on the surface fa. Either one in which the area of ​​the base and the area of ​​the tip are the same as shown in Fig. 3(a), or one in which the area of ​​the base and the area of ​​the tip are different as shown in Fig. 3(b) can be used. The height EH of the embossing projection from the surface fa to the tip is desirably set to 0.2 to 1.0 mm, preferably 0.4 to 0.8 mm. Fig. 3(c) is an enlarged plan view of a portion of the surface fa of the embossing roll a1. In Fig. 3(c), the area ratio of the embossed portion, which is the ratio of the area where the protrusions EP exist (the total area including the base portions) to the total area of ​​the surface fa (shown here as a rectangular area), is preferably set to 2.0 to 40.0%, more preferably 10.0 to 30.0%. By setting the embossing height and area ratio within the above ranges, the pulp surface of the composite nonwoven fabric is appropriately embossed, and the generation of paper dust during use of the composite nonwoven fabric is suppressed. The shape (cross-sectional shape) and arrangement of the embossed convex portions EP are not particularly limited, but the shape may be a circle as shown in Fig. 3(c), or other shapes such as a polygon, star, etc. The arrangement may be an aligned type as shown in Fig. 3(c), or an alternate type.

[0044] In the composite nonwoven fabric manufacturing apparatus shown in FIG. 1, a calendar device CA designed in accordance with the above-mentioned conditions is arranged downstream of the drying device 7, and an embossing device EA is arranged further downstream of that, so that the composite nonwoven fabric having the configuration according to the present invention can be efficiently manufactured. In other words, by subjecting the composite nonwoven fabric WP of the present invention to calendaring and heat embossing in that order in accordance with the above-mentioned conditions, even though it is a composite nonwoven fabric using a pulp fiber web produced by a dry airlaid method, it has the required volume and smoothness, as well as appropriate stiffness, and furthermore, fiber shedding is suppressed. It is also possible to perform the thermal embossing process and the calendaring process in the reverse order on the composite nonwoven fabric WP. However, in this case, the unevenness formed by the thermal embossing process is smoothed out by the subsequent calendaring process, resulting in a deterioration in stiffness. Furthermore, disadvantages such as a decrease in water absorption capacity have been confirmed. It is also possible to perform a thermal calendaring process on the composite nonwoven fabric WP. However, disadvantages such as a significant decrease in the thickness of the nonwoven fabric due to the heat being transferred while being pressed on a flat surface, resulting in a weakened stiffness and a decrease in water absorption capacity have been confirmed. Therefore, as described above, the dried composite nonwoven fabric WP can be subjected to a calendaring process without heating and then a thermal embossing process to form a composite nonwoven fabric that has the required volume and smoothness, as well as appropriate stiffness and reduced fiber shedding.

[0045] Note that FIG. 1 shows an example in which the calendering device CA and the embossing device EA are preferably added online, and it is preferable to provide the calendering device CA and the embossing device EA integrally with the nonwoven fabric wiper manufacturing apparatus in this manner. However, it is also possible to first wind up the nonwoven fabric wiper WP around a roller 81, and then perform calendering and embossing offline using the separately provided calendering device CA and embossing device EA.

[0046] (Example) Hereinafter, an example of a composite nonwoven fabric produced by supplying a pulp fiber web by the dry airlaid method using the above-mentioned production apparatus and carrying out a calendaring process and a heat embossing process will be described. The composite nonwoven fabrics of Examples 1 to 11 and Comparative Examples 1 to 6 (Table 2), which were manufactured to have the basis weight, bulk, D value, TS7 value, TS750 value, and thickness shown in Table 1, were subjected to sensory evaluation of the smoothness of the appearance of the composite nonwoven fabric, stiffness (strength), and fallen fibers according to the following criteria. In the calendar-treated and heat-embossed nonwoven fabrics, the pressed and heat-bonded areas could be visually confirmed. 1) Smoothness of appearance: The smoothness of the nonwoven fabric surface (feel and feel) was evaluated. Particularly excellent (Excellent ◎), no problems (Good 〇), rough and unpleasant to the touch (Fail ×) 2) Strength: Evaluated based on the firmness when touched. Strong and firm (Excellent ◎), No problem with strength (Good 〇), No firmness and soft (Fail ×) 3) Fallen fibers: The amount of fallen fibers during wiping was evaluated visually. Little fiber loss (good), much fiber loss (poor) The thickness (mm) and bulk (cm 3 / g) was measured as follows. Thickness (mm): 37.85g / cm2 measured with a Peacock paper thickness gauge 2 Measurements were taken under load. Volume (cm 3 / g): Thickness (cm) ÷ Basis weight (g / cm 2 ) was calculated.

[0047] [Table 1]

[0048] [Table 2]

[0049] As shown in Table 1 above, Examples 1 to 11 were capable of being provided as products, but as shown in Table 2 above, Comparative Examples 1 to 6 were unacceptable in terms of appearance smoothness, stiffness (strength), and fiber shedding.

[0050] The above Examples 1 to 11 have a basis weight of 40.0 to 110.0 g / m 2 , volume is 4.3~7.5cm 3 / g, TSA (D value) is 1.0 to 2.5 mm / N, and TSA (TS7 value) is 12.0 to 20.0 dBV 2 rms, TSA (TS750 value), which is an index of smoothness, is 33.0 to 100.0 dBV 2 The rms and thickness are preferably within the range of 0.30 to 0.50 mm, and the composite nonwoven fabric has the volume and smooth appearance required for the composite nonwoven fabric, as well as appropriate stiffness (strength) and reduced fiber shedding.

[0051] On the other hand, in Comparative Example 1, neither calendaring nor heat embossing was performed after drying, and the bulk and thickness were excessively high, giving it a sense of volume, but the evaluations of other items, such as smoothness of appearance, stiffness (strength), and fiber shedding were all unsatisfactory. In addition, Comparative Example 2 was only subjected to calendaring after drying, and the volume was moderate in terms of bulk and thickness, and the evaluation of the smoothness of the appearance and the amount of fallen fibers was good, but the required stiffness (strength) was lacking. In addition, Comparative Example 3 was subjected to only a heat embossing treatment after drying, and was excessively voluminous in terms of bulk and thickness, and was evaluated as having good stiffness (strength) and fiber loss, but lacked smoothness in appearance. Furthermore, Comparative Example 4 was subjected to a heat calendar treatment, and the volume was appropriate in terms of bulk and thickness, and the evaluations of the smoothness of the appearance and the amount of fallen fibers were good, but the required stiffness (strength) was lacking. In addition, in Comparative Example 5, the basis weight is 30.0 g / m 2 The thickness, bulk, D value, TS7 value and TS750 value are all outside the suitable range, and the evaluations for stiffness (strength) and fiber shedding are insufficient. In addition, in Comparative Example 6, the basis weight is 120.0 g / m 2This is too large, the thickness is outside the preferred range, and the smoothness of the appearance is insufficient.

[0052] The composite nonwoven fabrics in the above examples are those in which a pulp fiber web is supplied by a dry airlaid method, and it can be confirmed that the present invention is effective for composite nonwoven fabrics that use a pulp fiber web produced by a dry airlaid method. However, the present invention is not limited to this, and can also be applied to composite nonwoven fabrics that use a pulp fiber web obtained by a wet papermaking method. However, as mentioned above, the dry airlaid method can reduce manufacturing equipment and costs compared to the wet papermaking method.

[0053] This concludes the description of the embodiment, but it goes without saying that the present invention is not limited to the above embodiment, and can be implemented with various modifications without departing from the spirit of the present invention. [Explanation of symbols]

[0054] 1. Composite nonwoven fabric manufacturing equipment 2 Air Raid Equipment 3 Spunbond nonwoven fabric supply device 4 Suction device 5 Hydro-entangling device 6 Suction device 7 Drying equipment 8 Winding device 21 Fiberizer 22 Duct 23 Air Raid Hopper 24 Stacking position 28 Clamping roller 30 Pre-wetting device 31 Spray nozzle 32 Suction device 41 Suction device main body 42 Suction section 43 Transport Wire 51 Water Jet Head 52 Suction device 55 Transport Wire SW spunbond nonwoven fabric PF pulp fiber PFW Pulp Fiber Web PWeb Pre-Laminate (Laminate Web) WP composite nonwoven fabric TD Transport direction CA Calendar Device EA Embossing Machine A1 embossing roll (main roll) a2 Receiving roll

Claims

1. A composite nonwoven fabric in which a pulp fiber web is laminated and integrated onto a spunbond nonwoven fabric, The thickness is 0.30 to 0.50 mm, Basis weight: 40.0 to 110.0 g / m ２ and the volume is 4.3 to 7.5 cm ３ / g, TSA (D value) which is an index showing stiffness (strength) is 1.0 to 2.5 mm / N, and TSA (TS7 value) which is an index showing softness is 12.0 to 20.0 dBV. ２ TSA (TS750 value), which is an index showing rms and smoothness, is 33.0 to 100.0 dBV ２ is the rms, The spunbond nonwoven fabric is made of polypropylene, The composite nonwoven fabric is characterized in that the pulp fiber web is made of southern pine fibers as softwood bleached kraft pulp.

2. The pulp fiber web has a basis weight of 30.0 to 80.0 g / m ２ 2. The composite nonwoven fabric according to claim 1, wherein the weight ratio of the spunbond nonwoven fabric to the pulp fiber web is 40 / 60 to 10 / 90 (wt %).

3. The spunbond nonwoven fabric has a basis weight of 10.0 to 30.0 g / m ２ The spunbond nonwoven fabric is formed to include a plurality of fusion points that bond the spun resin fibers, and the area of ​​each fusion point is 0.10 to 0.50 mm ２ The area ratio of the fusion points per unit area is 7 to 20%, and the number of the fusion points is 10 to 150 / cm ２ 3. The composite nonwoven fabric according to claim 1 or 2,

4. A method for producing a composite nonwoven fabric in which a pulp fiber web is laminated and integrated onto a spunbond nonwoven fabric, comprising the steps of: The method includes at least a hydroentanglement step of promoting integration of the pulp fiber web and the spunbonded nonwoven fabric to obtain a laminate, and a drying step of drying the laminate after the hydroentanglement step, a calendering step of passing the laminate between calender rolls while applying pressure thereto after the drying step; The method further includes a heat embossing step of subjecting the pulp fiber web side to a heat embossing treatment after the calendaring step, In the hydroentanglement step, the basis weight is 30.0 to 80.0 g / m ２ and a pulp fiber web having a basis weight of 10.0 to 30.0 g / m ２ and the composite nonwoven fabric has a basis weight of 40.0 to 110.0 g / m2 as a whole. ２ The pulp fiber web and the spunbond nonwoven fabric are integrated together so as to form a In the calendering step and / or the heat embossing step, the bulk of the composite nonwoven fabric is 4.3 to 7.5 cm ３ / g, TSA (D value), which is an index of stiffness (strength), is 1.0 to 2.5 mm / N, and TSA (TS7 value), which is an index of softness, is 12.0 to 20.0 dBV. ２ TSA (TS750 value), which is an index showing rms and smoothness, is 33.0 to 100.0 dBV ２ The roll equivalent diameter of the main roll and the backing roll is calculated by the formula (roll equivalent diameter)=(main roll diameter)×(backing roll diameter) / {(main roll diameter)+(backing roll diameter)} in a range of 75 to 300 mm so as to satisfy rms, the conveying speed is set to 100 to 300 m / min, the gap between the rolls is set to 0 to 0.5 mm, and the roll nip pressure is set to 0.5 to 6.5 MPa. Furthermore, in the hot embossing step, the temperature of the main roll is set to 40 to 200° C., The pulp fiber web is made of southern pine fibers as softwood bleached kraft pulp, A method for producing a composite nonwoven fabric, characterized in that the spunbond nonwoven fabric is made of polypropylene.

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