Composite nonwoven fabric and method for producing the same

Abstract

To provide a conjugated nonwoven fabric that causes no stiff feeling when wiping and suppresses falling of pulp fibers while maintaining good appearance and wiping property.SOLUTION: A conjugated nonwoven fabric is formed by laminating a pulp fiber web on a spun-bonded nonwoven fabric so as to be integrated with each other. The conjugated nonwoven fabric has 0.115 to 0.150 of KES (MIU value) that is an indicator of average friction coefficient in a transportation direction during manufacture, 0.008 to 0.016 of KES (MMD value) that is an indicator of average deviation of friction coefficient, 50.0 to 140.0 g / m2 of basis weight, and 0.13 to 0.55 g / cm3 of density.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 of the pulp fibers and the strength of 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 together 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 therefore functions as a backing layer for the manufactured composite nonwoven fabric. 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, which has good absorbency for both aqueous and oily liquids, and a spunbond nonwoven fabric, which 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] In the composite nonwoven fabric obtained by hydroentangling a pulp fiber web and a spunbond nonwoven fabric as described above, the entanglement state between the fibers constituting the pulp fibers and the fibers constituting the spunbond nonwoven fabric tends to be insufficient.As a result, when wiping an object surface that is to be wiped, for example, when the surface is uneven, the pulp fibers of the composite nonwoven fabric obtained by hydroentangling a pulp fiber web and a spunbond nonwoven fabric tend to fall off.

[0006] One method that can be easily thought of to prevent the above-mentioned pulp fiber falling off is to promote entanglement of the fibers by increasing the water flow pressure during the hydroentanglement treatment. However, the surface of the pulp fiber web is disturbed by the high water pressure, which deteriorates the appearance and wiping properties of the composite nonwoven fabric after production, and also makes it feel rough to the touch when wiping.

[0007] An object of the present invention is to provide a composite nonwoven fabric that maintains its appearance and wiping properties, is free from stiffness during wiping, and suppresses shedding of pulp fibers, and also to provide a method for producing such a composite nonwoven fabric. [Means for solving the problem]

[0008] The object of the present invention is to provide a composite nonwoven fabric in which a pulp fiber web is laminated and integrated onto a spunbond nonwoven fabric, the composite nonwoven fabric having a KES (MIU value), which is an index showing the average coefficient of friction in the conveying direction during production, of 0.115 to 0.150, and a KES (MMD value), which is an index showing the average deviation of the coefficient of friction, of 0.008 to 0.016, and a basis weight of 50.0 to 140.0 g / m 2 , density 0.13~0.55g / cm 3 This can be achieved by a composite nonwoven fabric characterized in that:

[0009] The water absorption per unit volume is 0.75g / cm 3 More preferably, it is equal to or greater than this. The thickness is preferably 0.2 to 0.6 mm.

[0010] The TSA (TS7 value), which is an index of softness, is 11 to 23 dBV. 2 Preferably it is rms. In addition, the TSA (TS750 value), which is an index of smoothness, is 35 to 156 dBV. 2 Preferably it is rms.

[0011] The weight composition ratio of the pulp fiber web in the composite nonwoven fabric is preferably 77 to 85 (wt %). In addition, the water absorption per unit area is 310g / m 2 More preferably, it is equal to or greater than this.

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

[0013] The pulp fiber web is preferably made 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 object of the present invention is to provide a method for producing a composite nonwoven fabric according to any one of the above methods, The method includes at least a hydroentangling step of promoting integration of the pulp fiber web and the spunbond nonwoven fabric to obtain a laminate, and a drying step of drying the laminate after the hydroentangling step, a thermal calendering step of passing the laminate between calender rolls while applying heat and pressure after the drying step, This can also be achieved by a method for producing a composite nonwoven fabric, characterized in that in the thermal calendering step, a main roll and a backing roll are used whose roll equivalent diameter, calculated by the formula (roll equivalent diameter) = (main roll diameter) × (backing roll diameter) / {(main roll diameter) + (backing roll diameter)}, is 100 to 400 mm, and the conveying speed is set to 150 to 280 m / min, the gap between the rolls is 0 to 0.5 mm, and the roll linear pressure is set to 22 to 125 kg / cm.

[0015] The temperature of the roll is preferably set to 50 to 180°C. [Effects of the Invention]

[0016] According to the present invention, a composite nonwoven fabric can be provided that maintains its appearance and wiping properties, is free from a stiff feeling during wiping, and suppresses shedding of pulp fibers.Furthermore, such a composite nonwoven fabric can be produced. [Brief explanation of the drawings]

[0017] [Figure 1] FIG. 1 is a diagram showing a manufacturing apparatus for a composite nonwoven fabric. DETAILED DESCRIPTION OF THE INVENTION

[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 confirmed that a composite nonwoven fabric designed so that the KES (MIU value), an index indicating the average coefficient of friction, the KES (MMD value), an index indicating the mean deviation of the coefficient of friction, the basis weight, and the density are within specified ranges, and that the TSA (TS7 value), an index indicating the water absorption per unit volume, thickness, and softness, the TSA (TS750 value), an index indicating smoothness, the weight composition ratio of the pulp fiber web, and the water absorption per unit area are within specified ranges, have the appearance and wiping performance required of the product, are not stiff when wiping, and can suppress the shedding of pulp fibers, thereby arriving at the present invention. The composite nonwoven fabric can be produced by subjecting the fabric to a predetermined heat calendering treatment after the drying step.

[0019] The composite nonwoven fabric preferably has a KES (MIU value), an index showing the average coefficient of friction, of 0.115 to 0.150 in the conveying direction during production (i.e., the direction in which the raw fabric is run).Furthermore, the composite nonwoven fabric preferably has a KES (MMD value), an index showing the average deviation of the coefficient of friction, of 0.008 to 0.016 in the same direction. When the KES (MIU value) and KES (MMD value) of the composite nonwoven fabric are within the above ranges, the surface properties such as surface friction become suitable for wiping applications, and the shedding of pulp fibers during wiping can be suppressed. The basis weight of the composite nonwoven fabric is measured in accordance with JIS P8124, and the basis weight is 50.0 to 140.0 g / m 2 It is preferable that: The density of the composite nonwoven fabric is 0.13~0.55g / cm 3 The thickness of the composite nonwoven fabric is preferably 37.85 gf / cm2 as measured by a Peacock paper thickness gauge. 2 The density can be calculated by dividing the basis weight by the thickness.

[0020] Furthermore, it is preferable that the composite nonwoven fabric is designed so that the water absorption, thickness, TSA (TS7 value), which is an index indicating softness, weight composition ratio of the pulp fiber web, etc. are within predetermined ranges. These preferable ranges are further explained below.

[0021] The total water absorbency (TWA) was measured by cutting a composite nonwoven fabric sheet into a 76mm x 76mm square to prepare a sample and measuring its dry weight. The sample was then immersed in distilled water for 2 minutes, and then placed in a container saturated with water vapor (100% RH) with one corner of the sample positioned at the top. The top and the two adjacent corners were supported and the sample was hung in a stretched state, left for 30 minutes, and the weight was calculated after draining. The measured value was then measured for 1m of the sample. 2 Water absorption per unit (g / m 2) can be calculated by converting it into the water absorption per unit volume (g / cm 3 ) is the water absorption per unit area (g / cm 2 ) by the thickness of the nonwoven fabric (cm). The water absorption per unit area (g / m 2 ) is the water absorption per unit area of ​​a composite nonwoven fabric and is a general indicator of water absorption performance. Also, the water absorption per unit volume (g / cm 3 ) is the water absorption per unit volume of a composite nonwoven fabric, and a high value indicates that the nonwoven fabric has a high water absorption capacity despite its thin thickness. The water absorption per unit volume of the composite nonwoven fabric of the present invention is 0.75 g / cm 3 More preferably, it is equal to or greater than this. The water absorption per unit area is 310g / m 2 More preferably, it is equal to or greater than this.

[0022] Furthermore, the composite nonwoven fabric of the present invention is preferably designed so that the TSA (TS7 value), which is an index of softness, and the TSA (TS750 value), which is an index of smoothness, are within a predetermined range. The TSA (TS7 value) is 11 to 23 dBV. 2 It is preferable that the TSA (TS750 value) is 35 to 156 dBV. 2 Preferably it is rms. When the TSA (TS7 value) and TSA (TS750 value) of the composite nonwoven fabric are within the above ranges, the surface softness and roughness are suitable for wiping applications and there is no stiff feeling, which is preferable.

[0023] The above-mentioned TS7 value and TS750 value are indicated as TSA (TS7 value) and TSA (TS750 value) to indicate that they were measured using a tissue softness analyzer (TSA). The TSA tissue softness analyzer quantitatively evaluates the softness (hand feel) of nonwoven fabrics and other materials by applying a bladed rotor, for example, with a pressure of 100 mN to a composite nonwoven fabric (sample) placed on a sample stage with the pulp side facing up, and rotating it at 2.0 s. The vibration data detected by various sensors is analyzed and parameterized (TS value) to quantitatively evaluate the softness (hand feel) of nonwoven fabrics and other materials. This is the product name of Emtec Electronic GmbH of Germany (distributed in Japan by 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, etc., and the rotation speed of the blade. The horizontal vibration of the blade itself (resonance frequency: for example, 6500 Hz) is induced when the blade moves along the surface of the sample, due to momentary interruption by the 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 taken as the TS7 value (dBV 2 rms).

[0024] The software used to perform vibration analysis and parameterization (TS values) can be the emtec measurement system. This software is equipped with various algorithms (e.g., Base Tissue, Facial, TP, etc.), and the TS7 and TS750 values ​​are automatically acquired. The HF (hand feel) value is calculated from these TS7 and TS750 values ​​or from basis weight, thickness, number of plies, etc., depending on the type of algorithm. In the present invention, the TS7 and TS750 values ​​are specified, rather than the HF value. Any algorithm can be used as long as the measurement conditions are met, and the TS7 and TS750 values ​​do not change depending on the type of algorithm. The surface properties of the composite nonwoven fabric according to the present invention were measured using an automated surface testing machine KES-FB4-AUTO-A manufactured by Kato Tech Co., Ltd. Measurements were carried out three times at a compression speed of 1 mm / sec, with the friction probe being a 10 mm square piano wire, the initial load of the friction probe being 25 gf, the initial load of the roughness contact probe being 10 gf, and a 400 g weight being used when attaching the sample. This allows us to obtain the KES (MIU value), which is the average coefficient of friction of the composite nonwoven fabric, and the KES (MMD value), which is an index showing the mean deviation of the coefficient of friction. The higher the mean coefficient of friction value, the less slippery it is. Also, the higher the mean deviation of the coefficient of friction value, the less smooth it is and the more rough it is.

[0025] As described above, the basis weight of the composite nonwoven fabric according to the present invention is 50.0 to 140.0 g / m 2 The thickness is preferably 0.2 to 0.6 mm, and the weight composition ratio of the pulp fiber web is preferably 77 to 85 (wt %) in the composite nonwoven fabric according to the present invention. A composite nonwoven fabric formed so that the above-mentioned multiple factors fall within a specified range can be made to maintain its appearance and wiping properties, while not feeling stiff when wiping and suppressing the shedding of pulp fibers. The composite nonwoven fabric that is the final product is required to have a certain strength, and whether the spunbond nonwoven fabric has resulted in a product with appropriate rigidity can be determined by evaluating strength (ease of tearing), etc.

[0026] 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, of which polypropylene is preferred. 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.

[0027] The process for producing the composite nonwoven fabric of the present invention will be described below. The composite nonwoven fabric of the present invention can be produced efficiently by a drying process followed by a predetermined thermal calendering process. Here, the main components of the manufacturing apparatus for producing the composite nonwoven fabric WP will be described, followed by a description of the thermal calendering apparatus and the thermal calendering process.

[0028] The composite nonwoven fabric manufacturing apparatus 1 shown in Figure 1 has an airlaid device 2 on the upstream side, a spunbond supply device 3 that supplies 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 conveyance direction TD, downstream of these devices 2, 3, and 4 are arranged, in this order from the upstream side, a hydroentangling device 5 that sprays water jets for hydroentangling 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 continuously produced composite nonwoven fabric WP. The manufacturing apparatus 1 is further provided with a thermal calender CA between the drying device 7 and the winding device 8 for subjecting the dried nonwoven fabric WP to a thermal calendering treatment (calendering treatment while heating).

[0029] Starting from the upstream side, the airlaid device 2 includes a defibrator 21 that defibrates 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.

[0030] An airlaid hopper 23 is disposed downstream of the duct 22. Inside the 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 bottom 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 a device 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 one airlaid hopper 23 and one 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.

[0031] A transport wire 43 for transporting the web is disposed around the suction device 4. The transport wire 43 is arranged so that the pulp fiber web PFW, on which the pulp fibers PF have been 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 below. The conveying wire 43 is formed in an open mesh form so that the suction force of the suction portion 42 reaches the opposite side (upper side).

[0032] 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 prepared in advance and set in this spunbond supplying device 3. The spunbond nonwoven fabric SW is drawn 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 synthetic resin formed by the spunbonding method.

[0033] The pulp fiber web PFW described above is placed on 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 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.

[0034] 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 introduced into the downstream hydroentangling device 5 in this state, there is a risk that some of the pulp fibers PF will be blown up by the water jet (high-pressure water flow). Therefore, the present manufacturing apparatus 1 is provided with clamping rollers 28 for sandwiching the preliminary laminate PWeb from above and below to stabilize the state in which the pulp fiber web PFW is placed on the spunbond nonwoven fabric SW, and a pre-wetting device 30 for applying moisture to prevent fiber 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 below the preliminary laminate PWeb (i.e., the underside of the pulp fiber web PFW). 1 illustrates the case where the pre-wetting device 30 is provided as a new device before the hydroentangling device 5 as described above, but the present invention is not limited to this. The hydroentangling device 5 may be designed so that the first set of multiple 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 pre-wetting devices as described above is effective in reducing equipment costs.

[0035] Then, in the hydroentangling device 5, high-pressure water jets are sprayed onto the preliminary laminate PWeb, which has been processed by the clamping rollers 28 and the pre-wetting device 30, which serve as the pre-treatment section, to promote entanglement of the pulp fibers. This promotes integration of the upper pulp fiber web PFW layer with the lower spunbond nonwoven fabric SW layer. 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 a 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 these water jet nozzles is preferably 0.06 to 0.15 mm. The spacing between the water jet nozzles is preferably 0.4 to 1.0 mm.

[0036] The water pressure during the hydroentanglement treatment is preferably 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.

[0037] 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 on the lower side, or penetrate through the spunbond nonwoven fabric SW to the opposite side. This action promotes integration of the two layers.

[0038] A conveying wire 55 is also provided in the hydroentangling device 5. The conveying wire 55 receives the preliminary laminate PWeb downstream of the pre-treatment units 28, 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 hydroentangling treatment as it moves downstream in the transport direction TD, and by the time it leaves the hydroentangling 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.

[0039] 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. In this way, dehydration and drying by the suction device 6 and the dryer 7 at the latter stage of the production of the composite nonwoven fabric WP allows the nonwoven fabric to be produced efficiently, and if the hydroentangled nonwoven fabric produced is dried without applying a large external pressure, a bulky nonwoven fabric can be produced as described above. The suction device 6 is, for example, a vacuum type, and dehydrates the nonwoven fabric after hydroentanglement. A non-compression type dryer, preferably an air-through dryer, is preferably used as the drying device 7. In Fig. 1, the rotatable air-through dryer body 71 is a cylindrical body with a number of through-holes 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.

[0040] Conventionally, continuously produced composite nonwoven fabric WP has generally been wound around roller 81 of winding device 8, but in the manufacturing apparatus shown in Figure 1, a thermal calendar device CA is arranged as a post-processing device between the drying device 7 and winding device 8. A pair of plain-surfaced calendar rolls (not shown) are arranged inside the thermal calendar device CA, and the composite nonwoven fabric WP is clamped and transported between them with a predetermined range of roll linear pressure (clamping pressure). There is no limitation on the material of each calender roll as long as the outer peripheral surface is formed to be flat, but it is preferable that both are steel plain rolls made of metal. A heater is disposed inside at least one of the calender rolls so that thermal calendering can be performed.

[0041] The thermal calendering conditions for the thermal calendering device CA are preferably set so that the roll temperature is 50 to 180°C, the gap between the rolls is 0 to 0.5 mm, and a roll linear pressure of 22 to 125 kg / cm is applied to the composite nonwoven fabric WP passing between the rolls. Also, the roll conveying speed is preferably set to 150 to 280 m / min.

[0042] The pair of metal rolls are arranged horizontally, one above the other, and the dried composite nonwoven fabric passes between them. The upper roll is the main roll and the lower roll is the receiving roll. The main roll and backing roll are preferably designed so that the roll-equivalent diameter calculated by the formula (roll equivalent diameter) = (main roll diameter) × (backing roll diameter) / {(main roll diameter) + (backing roll diameter)} is 100 to 400 mm. The roll-equivalent diameter here is based on the literature presented by AV Lyons et al. (1990 TAPPI Finishing and Converting, p. 5) and is an index of the strength of the calendering treatment applied to the composite nonwoven fabric.

[0043] For example, if the roll equivalent diameter is less than 100 mm, the conveying speed is faster than 280 m / min, the gap is greater than 0.5 mm, the linear pressure is less than 22 kg / cm, or the roll temperature is lower than 50°C, the pressure and heat energy applied to the surface of the composite nonwoven fabric will be too small, reducing the effect of smoothing the surface and making it difficult to prevent fiber shedding when wiping an uneven surface. Conversely, if the roll equivalent diameter is greater than 400 mm, the conveying speed is slower than 150 m / min, the linear pressure is greater than 125 kg / cm, or the temperature is greater than 180°C, the pressure and thermal energy applied to the surface of the composite nonwoven fabric will be too great, causing the surface of the composite nonwoven fabric to harden, resulting in a decrease in thickness and an excessively high density. This will result in a hard, paper-like feel, making the wiper less user-friendly. Furthermore, there may be the inconvenience of part of the spunbond nonwoven fabric melting due to the heat and transferring to the roll surface. When the heater is disposed inside either the upper main roll or the lower backing roll, it is preferable to dispose the heater inside the upper main roll, because the pulp fiber web PFW layer is located on the upper side for convenience of the device, and heating the pulp fiber web PFW layer is more effective in suppressing bulkiness.

[0044] In the composite nonwoven fabric manufacturing apparatus shown in Figure 1, a thermal calendar device CA designed in accordance with the above-mentioned conditions is placed downstream of the drying device 7, so that the composite nonwoven fabric of the present invention can be efficiently manufactured. In other words, by subjecting the composite nonwoven fabric WP of the present invention to a calendaring treatment according to the above-mentioned conditions, it is possible to form a fabric having a smooth surface and suppressed shedding of pulp fibers while maintaining the appearance and wiping properties required of the product.

[0045] Note that Figure 1 shows an example in which a thermal calender CA is preferably added online, and it is preferable to provide the thermal calender CA integrally with the nonwoven fabric wiper manufacturing apparatus in this way, but it is also possible to first wind the nonwoven fabric wiper WP around a roller 81 and then perform thermal calendering offline using a separately provided thermal calender CA.

[0046] In the manufacturing apparatus shown in Figure 1, the laminate is subjected to a thermal calendering treatment after the drying step, thereby adjusting the compression state of the manufactured composite nonwoven fabric. This allows for the production of a composite nonwoven fabric that maintains its appearance and wiping properties while being free of stiffness and that is particularly resistant to shedding of the pulp fiber web when wiping an uneven surface. This is because the thermal calendering treatment in a dry state compresses the pulp fibers within the composite nonwoven fabric, increasing the adhesion between the pulp fibers and promoting surface smoothing. This reduces the chance of pulp fibers getting caught when wiping an uneven surface, thereby preventing fiber shedding. In the composite nonwoven fabric of the present invention, no treatment that increases the water pressure is used in the hydroentanglement step, so the surface of the pulp fiber web is not disturbed, and the appearance and wiping properties can be maintained.

[0047] One possible method for smoothing the surface of a composite nonwoven fabric is to treat it with a press roll while it is wet before the drying process. However, this promotes bonding between the fibers, and the fibers do not return to a low density state when they absorb water, resulting in a decrease in water absorption performance and poor wiping properties. As mentioned above, a plain roll is preferable as the calender roll. For example, if an embossed roll is used, unevenness will be formed on the surface of the nonwoven fabric, making it difficult to prevent fiber shedding when wiping the uneven surface. Furthermore, calendering without applying heat has a low compression energy, so the effect of smoothing the surface is reduced.

[0048] (Example) The composite nonwoven fabric of the example produced by the above-mentioned production apparatus through the drying step and the heat calendering treatment will be described below. The composite nonwoven fabrics of Examples 1 to 12, which were manufactured so that the KES (MIU value), an index showing the average coefficient of friction in the conveying direction during manufacturing, the KES (MMD value), an index showing the average deviation of the coefficient of friction, the basis weight, density, thickness, and weight composition ratio of the pulp fiber web (pulp / composite nonwoven fabric) were as shown in Table 1, and Comparative Examples 1 to 4 (Table 2), were evaluated for water absorption per area (g / m) according to the following criteria. 2 ) and water absorption per density (g / cm 3 ), TSA (TS7 value) which is an index of softness, TSA (TS750 value) which is an index of smoothness, appearance of the composite nonwoven fabric, amount of wiping paper powder remaining on the uneven surface, stiffness, resistance to breakage, and wiping ability were evaluated.

[0049] The evaluation criteria are as follows: 1) Water absorption amount The water absorption performance was confirmed using two types of TWA values. TWA(g / m 2 ): Water absorption per unit area of ​​the composite nonwoven fabric. TWA(g / cm 3 ): The water absorption per unit volume of the composite nonwoven fabric. A high value indicates a high water absorption capacity despite a low thickness. 2)TSA TSA (TS7 value), an index of softness TSA (TS750 value), an index of smoothness If these values ​​are high, the surface of the nonwoven fabric becomes hard and rough, and the feeling of stiffness increases. 3) KES KES (MIU value), an index showing the average coefficient of friction KES (MMD value) is an index showing the mean deviation of the friction coefficient If these values ​​are high, the surface of the nonwoven fabric becomes less slippery and rougher, resulting in a large amount of wiping paper dust. By using a plain calender roll, the KES (MIU value) of the composite nonwoven fabric is reduced to 0.015, and the KES (MMD) value is reduced to about 0.008. 4) Appearance: The cosmetic appearance of the composite nonwoven fabric was evaluated on a 5-point scale. Those with no cosmetic issues were given a rating of "3," those slightly better than "3" were given a rating of "2," and those that were excellent were given a rating of "1." Conversely, those slightly worse than "3" were given a rating of "4," and those that were poor were given a rating of "5." 5) Amount of paper dust removed from uneven surfaces: The amount of paper dust removed when wiping an uneven plastic plate was evaluated. The equipment used for the evaluation is disclosed in JP 2019-203734 A. Specifically, a plastic plate measuring 18 cm in length and 5 mm in thickness, with two rows of seven 1 cm diameter holes spaced 1.1 cm apart per row, was placed on black construction paper. The surface of the plate was swung back and forth in the CD direction of a four-ply nonwoven fabric with a load of three 5.1 cm diameter, 685 g weights (total 2.055 kg) applied across the surface. The amount of paper dust that fell below the holes was visually evaluated when the plate was swung back and forth 100 times in 120 seconds. A product with no problems was given a rating of "3," a product slightly better than a "3" was given a rating of "2," and a product that was excellent was given a rating of "1." Conversely, a product slightly worse than a "3" was given a rating of "4," and an inferior product was given a rating of "5." 6) Roughness: The feel of the composite nonwoven fabric was evaluated on a 5-point scale. Those that were not problematic in terms of hardness or stiffness when used were given a rating of "3," those that were slightly better than "3" were given a rating of "2," and those that were excellent were given a rating of "1." Conversely, those that were slightly worse than "3" were given a rating of "4," and those that were worse were given a rating of "5." 7) Tear resistance: The ease with which the composite nonwoven fabric can be torn when worn was evaluated on a 5-point scale. Those that had no problems with strength (ease of tearing) when used were given a rating of "3," those that were slightly better than "3" were given a rating of "2," and those that were excellent were given a rating of "1." Conversely, those that were slightly worse than "3" were given a rating of "4," and those that were poor were given a rating of "5." 8) Wiping ability: The wiping ability of the composite nonwoven fabric was evaluated when wiping off dirt or other contaminants. Those with no problems in terms of flexibility or water absorption were given a rating of "3," those slightly better than "3" were given a rating of "2," and those that were excellent were given a rating of "1." Conversely, those slightly worse than "3" were given a rating of "4," and those that were poor were given a rating of "5."

[0050] [Table 1]

[0051] [Table 2]

[0052] Examples 1 to 12 shown in Table 1 above can be provided as products, but Comparative Examples 1 to 7 shown in Table 2 above either did not receive sufficient evaluations in terms of appearance, amount of paper dust, stiffness, or wiping ability, or were inferior in water absorption performance and durability that are fundamentally required of nonwoven fabrics, and therefore cannot be provided as nonwoven fabric products.

[0053] In the above Examples 1 to 12, the KES (MIU value), which is an index showing the average coefficient of friction in the conveying direction during production, is 0.115 to 0.150, and the KES (MMD value), which is an index showing the average deviation of the coefficient of friction, is 0.008 to 0.016, and the basis weight is at least 50.0 to 140.0 g / m 2 , density 0.13~0.55g / cm 3 Within this preferred range, the appearance and wiping properties required for a composite nonwoven fabric are maintained while the shedding of pulp fibers is suppressed.

[0054] On the other hand, Comparative Examples 1 to 7 are unsuitable for products as follows. In Comparative Example 1, the basis weight is too low, so the water absorbency is low and the wiping properties are poor. In Comparative Example 2, the KES (MMD value) was too high, so the paper was rough and produced an inferior amount of paper dust. In Comparative Example 3, the KES (MIU value) was too high, so the surface was not slippery and the amount of paper dust was poor. Comparative Example 4 has too high a density, so is hard and has poor stiffness. In Comparative Example 5, the basis weight was too high, so the amount of pulp was large and the stiffness was poor. In Comparative Example 6, the density was too low, resulting in large voids and poor appearance. In Comparative Example 7, the KES (MIU value) was too low, so the wipeability was too slippery and poor.

[0055] The composite nonwoven fabrics in the above examples are those in which a pulp fiber web is supplied dry using a dry airlaid method. However, the present invention is not limited to this and can be similarly applied to composite nonwoven fabrics that use a pulp fiber web obtained wet, such as a wet papermaking method. However, the dry airlaid method described above can reduce the manufacturing equipment and costs compared to wet methods.

[0056] 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 within the scope of the gist of the present invention. [Explanation of symbols]

[0057] 1. Composite nonwoven fabric manufacturing equipment 2 Airlaid 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 Conveying wire 51 Water Jet Head 52 Suction device 55 Carrying wire SW spunbond nonwoven fabric PF pulp fiber PFW Pulp Fiber Web PWeb Pre-Laminate (Laminate Web) WP composite nonwoven fabric TD conveying direction CA Heat Calender

Claims

1. A composite nonwoven fabric in which a pulp fiber web is laminated and integrated onto a spunbond nonwoven fabric, the KES (MIU value), which is an index showing the average coefficient of friction in the conveying direction during production, being 0.115 to 0.150, and the KES (MMD value), which is an index showing the average deviation of the coefficient of friction, being 0.008 to 0.016, and the basis weight being 50.0 to 140.0 g / m ２ , density is 0.13 to 0.55 g / cm ３ A composite nonwoven fabric characterized by:

2. Water absorption per unit volume is 0.75 g / cm ３ 2. The composite nonwoven fabric according to claim 1, wherein the above-mentioned

3. 3. The composite nonwoven fabric according to claim 1, wherein the thickness is 0.2 to 0.6 mm.

4. TAS (TS7 value), an index of softness, is 11 to 23 dBV ２ 4. The composite nonwoven fabric according to claim 1, wherein the nonwoven fabric is rms.

5. TAS (TS750 value), an index of smoothness, is 35 to 156 dBV ２ 5. The composite nonwoven fabric according to claim 1, wherein the nonwoven fabric is rms.

6. 6. The composite nonwoven fabric according to claim 1, wherein the weight ratio of the pulp fiber web in the composite nonwoven fabric is 77 to 85 (wt %).

7. Water absorption per unit area: 310 g / m ２ 7. The composite nonwoven fabric according to any one of claims 1 to 6, characterized in that:

8. The composite nonwoven fabric according to any one of claims 1 to 7, characterized in that the material of the spunbond nonwoven fabric is one or a mixture of two or more selected from the group consisting of nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, and polystyrene.

9. The composite nonwoven fabric according to any one of claims 1 to 8, characterized in that the pulp fiber web is made 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.

10. A method for producing the composite nonwoven fabric according to any one of claims 1 to 9, The method includes at least a hydroentangling step of promoting integration of the pulp fiber web and the spunbond nonwoven fabric to obtain a laminate, and a drying step of drying the laminate after the hydroentangling step, a thermal calendering step of passing the laminate between calender rolls while applying heat and pressure after the drying step, a main roll and a backing roll having a roll equivalent diameter of 100 to 400 mm, calculated by the formula (roll equivalent diameter) = (main roll diameter) × (backing roll diameter) / {(main roll diameter) + (backing roll diameter)}, and a conveying speed of 150 to 280 m / min, a gap between the rolls of 0 to 0.5 mm, and a roll linear pressure of 22 to 125 kg / cm.

11. 11. The method for producing a composite nonwoven fabric according to claim 10, wherein the temperature of the roll is set to 50 to 180°C.

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