Conjugate type nonwoven fabric

Abstract

To provide a conjugate type nonwoven fabric that is excellent in water absorbability of a sheet 3 and cost and causes less color unevenness.SOLUTION: A conjugate type nonwoven fabric is formed by integrally laminating a pulp fiber web on a spun-bonded nonwoven fabric and includes a pulp fiber web that is not colored with dye and a colored spun-bonded nonwoven fabric. A printed part 2 printed with ink is provided on a surface of the conjugate type nonwoven fabric. Color difference ΔE*ab between the conjugate type nonwoven fabric and the printed part 2 is 20 or less. Basis weight of the conjugate type nonwoven fabric is 45 to 85 g / m2. Percentage of the spun-bonded nonwoven fabric is 10 to 30 mass%. Percentage of the pulp fiber web is 70 to 90 mass%. Square root GMT of tensile strength WMDT in MD direction during wet and tensile strength WCDT in CD direction during wet based on JIS P 8135 is 10.0 to 25.0 N / 25 mm. Water absorption speed is 5.0 seconds or less. Amount of water absorption is 220 g / m2 or more.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a composite nonwoven fabric. [Background technology]

[0002] There is a technology to produce a sheet that combines strength and liquid absorption by hydroentangling a spunbond nonwoven fabric made from pulp fibers, which have excellent absorbency for water-based and oil-based liquids, and synthetic fibers, which have excellent strength.Composite nonwoven fabrics made using this technology combine wet strength with liquid absorption and liquid retention, and can be used in a wide range of applications, such as on the surfaces of machinery, equipment, and utensils used in food manufacturing, processing, and cooking, or for wiping workers' hands.

[0003] In recent years, sheet- or roll-shaped wipers and paper towels using the above-mentioned composite nonwoven fabrics have been sold on the market, and these wipers and paper towels come in a variety of colors, such as colored and colorless (white), and colored wipers and paper towels are desired from the viewpoints of aesthetics and visibility.

[0004] Such wipers and paper towels require wet strength and absorbency to quickly wipe away dirt, etc. In food processing environments, for example, where meat and fish are the main target, they must be able to quickly absorb drips and have ample absorption capacity. In addition, high wet strength is required to prevent tearing of food paper due to drips. Summary of the Invention [Problem to be solved by the invention]

[0005] However, if pulp fibers are dyed to obtain a colored sheet, there is a possibility that problems will occur such as the dye easily leaching into the object or solution when the sheet is used to wipe off dirt or other stains.

[0006] In recent years, when considering composite nonwoven fabrics for use as sheets, attempts have been made to color spunbond nonwoven fabrics that have already been colored with pigments by compounding them with white pulp fibers. However, sheets produced using this method have a lot of unevenness due to the difference in color between the spunbond nonwoven fabric and the pulp fibers, and there is room for improvement in terms of aesthetic appeal.

[0007] In order to reduce color unevenness in the composite nonwoven fabric, it is conceivable to increase the basis weight of the spunbond nonwoven fabric, but this would increase costs because spunbond nonwoven fabrics are generally more expensive than pulp fibers.On the other hand, it is conceivable to reduce the amount of pulp fibers and increase the proportion of spunbond nonwoven fabric, but in this case the water absorption performance of the sheet would decrease.

[0008] The present invention has been made in view of the above circumstances, and has as its object to provide a composite nonwoven fabric which is excellent in water absorption performance and cost, and which has little color unevenness. [Means for solving the problem]

[0009] As a result of extensive research by the inventors to solve the above problems, they have discovered a composite nonwoven fabric obtained by laminating a pulp fiber web on a spunbond nonwoven fabric and integrating the fabric, the composite nonwoven fabric comprising a pulp fiber web that is not colored with dyes and a colored spunbond nonwoven fabric, the surface of the composite nonwoven fabric being provided with a printed portion printed with ink, the color difference ΔE*ab between the composite nonwoven fabric and the printed portion being 20 or less, and the composite nonwoven fabric having a basis weight of 45 to 85 g / m 2 The composite nonwoven fabric contains a spunbond nonwoven fabric in a proportion of 10 to 30% by mass, and a pulp fiber web in a proportion of 70 to 90% by mass. The wet tensile strength in the MD direction (WMDT) and the wet tensile strength in the CD direction (WCDT) according to JIS P 8135 (GMT) are 10.0 to 25.0 N / 25 mm, the water absorption rate is 5.0 seconds or less, and the water absorption amount (TWA) is 220 g / m. 2 The inventors have found that a composite nonwoven fabric can be obtained as described above, and have completed the present invention.

[0010] That is, the present invention provides the following.

[0011] (1) A composite nonwoven fabric is formed by laminating a pulp fiber web on a spunbond nonwoven fabric and integrating the two. The composite nonwoven fabric comprises a pulp fiber web that is not dyed with a dye and a colored spunbond nonwoven fabric. The surface of the composite nonwoven fabric is provided with a printed portion printed with ink, and the color difference ΔE*ab between the composite nonwoven fabric and the printed portion is 20 or less. The composite nonwoven fabric has a basis weight of 45 to 85 g / m. 2 The composite nonwoven fabric contains 10 to 30% by mass of the spunbond nonwoven fabric, and 70 to 90% by mass of the pulp fiber web. The composite nonwoven fabric has a square root GMT of the product of the wet tensile strength in MD direction WMDT and the wet tensile strength in CD direction WCDT according to JIS P 8135 of 10.0 to 25.0 N / 25 mm, a water absorption rate of 5.0 seconds or less, and a water absorption amount (TWA) of 220 g / m. 2 This is the composite nonwoven fabric. (2) The composite nonwoven fabric according to (1) has a square root GMT of the product of the tensile strength in the MD direction in a dry state (DMDT) and the tensile strength in the CD direction in a dry state (DCDT) according to JIS P 8113 of 12.0 to 25.0 N / 25 mm. (3) The composite nonwoven fabric according to (1) or (2) has a square root GMT of the product of the tensile strength DMDT in the MD direction when dry and the tensile strength DCDT in the CD direction when dry, as measured in accordance with JIS P 8113, of 6.0 to 15.0 N / 25 mm. (4) The spunbond nonwoven fabric includes 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 in the spunbonded nonwoven fabric is 7 to 20%, and the number of the fusion points per unit area in the spunbonded nonwoven fabric is 10 to 150 / cm 2The composite nonwoven fabric according to (1) or (2) above, wherein the spunbond nonwoven fabric contains at least one material selected from the group consisting of nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, and polystyrene, and the pulp fiber web contains fibers of at least one softwood bleached kraft pulp selected from the group consisting of radiata pine, slash pine, southern pine, lodgepole pine, spruce, and Douglas fir. [Effects of the Invention]

[0012] According to the present invention, a composite nonwoven fabric can be provided which is excellent in water absorption performance and cost performance of the sheet and has little color unevenness. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing an example of a composite nonwoven fabric according to the present embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a mode for carrying out the present invention (hereinafter simply referred to as "the present embodiment") will be described in detail. The following present embodiment is an example for explaining the present invention, and is not intended to limit the present invention to the following content. The present invention can be carried out by appropriately modifying it within the scope of its gist.

[0015] Unless otherwise specified, the MD direction of a composite nonwoven fabric is the machine direction in which the composite nonwoven fabric is manufactured, and the CD direction is the cross direction perpendicular to the machine direction.

[0016] In the drawings, the same elements are denoted by the same reference numerals, and redundant explanations will be omitted. Furthermore, unless otherwise specified, the positional relationships, such as up, down, left, and right, are based on the positional relationships shown in the drawings. Furthermore, the dimensional ratios of the drawings are not limited to those shown in the drawings.

[0017] 1 is a perspective view showing an example of the composite nonwoven fabric according to the present embodiment, which will be described below with reference to FIG.

[0018] <Composite nonwoven fabric>

[0019] The composite nonwoven sheet 3 shown in Fig. 1 is a composite nonwoven fabric obtained by laminating and integrating a pulp fiber web onto a spunbond nonwoven fabric, and includes a pulp fiber web that is not colored with dyes and a colored spunbond nonwoven fabric. The surface of the composite nonwoven fabric is provided with a printed portion 2 printed with ink, and the color difference ΔE*ab between the composite nonwoven fabric and the printed portion 2 is 20 or less. The basis weight of the composite nonwoven fabric is 45 to 85 g / m 2 The composite nonwoven fabric contains 10 to 30% by mass of spunbond nonwoven fabric, and 70 to 90% by mass of pulp fiber web. Furthermore, the composite nonwoven fabric has a square root (GMT) of the wet tensile strength in MD (WMDT) and wet tensile strength in CD (WCDT) according to JIS P 8135 of 10.0 to 25.0 N / 25 mm, a water absorption rate of 5.0 seconds or less, and a water absorption amount (TWA) of 220 g / m. 2 That's all. The sheet 3 made of such a composite nonwoven fabric has excellent water absorption and cost performance, and has little color unevenness, making it aesthetically pleasing and highly visible. Furthermore, when using the sheet 3 to wipe away dirt and other stains, it can prevent problems such as dyes easily leaching out into the object or solution.

[0020] The present inventors have thoroughly studied the use of sheets containing colored composite nonwoven fabrics and have found that conventional sheets, for example, when colored with a dye to pulp, have a drawback in that the color easily leaches into the object or solution when wiped with the sheet. As another example, conventional sheets are colored by combining a white pulp fiber web with a spunbond nonwoven fabric that has been pre-colored with a pigment. However, the spunbond nonwoven fabric is made of long fibers and has a lower basis weight than pulp, and the colored fibers do not entangle uniformly with the pulp fiber web, which tends to result in uneven color due to the difference in color between the spunbond nonwoven fabric and the pulp fiber web, resulting in poor aesthetic appeal. In response to this, the inventors have found that increasing the basis weight of the spunbond nonwoven fabric to reduce color unevenness increases costs, while reducing the amount of pulp fiber web and increasing the proportion of the spunbond nonwoven fabric results in reduced water absorption, making it difficult to achieve both at a high level. Focusing on these points, we conducted extensive research to resolve these problems and unexpectedly discovered that the composite nonwoven fabric of this embodiment, which has an ink-printed portion 2, can suppress color unevenness, reduce costs, and achieve high levels of water absorption performance (however, the actions and effects of this embodiment are not limited to these).

[0021] Here, "less color unevenness" means that in a composite nonwoven fabric having a printed portion 2 printed with ink, unevenness due to the color difference between the pulp fiber web that is not dyed with dye and the colored spunbond nonwoven fabric is not noticeable, resulting in excellent cosmetic properties.

[0022] The composite nonwoven fabric of this embodiment is a composite nonwoven fabric in which a pulp fiber web is laminated and integrated onto a spunbond nonwoven fabric, and includes a pulp fiber web that is not colored with dye and a colored spunbond nonwoven fabric.

[0023] (spunbond nonwoven fabric)

[0024] The spunbond nonwoven fabric preferably includes a plurality of fusion points that bond the spun resin fibers. 2 It is preferable that the area ratio of fusion points per unit area in the spunbonded nonwoven fabric is 7 to 20%, and the number of fusion points per unit area in the spunbonded nonwoven fabric is 10 to 150 / cm. 2 When any one of the area, area ratio, and number of fusion-bonded points is within the above-mentioned range, a composite nonwoven fabric with less fiber shedding in water can be obtained. The shape of the fusion-bonded points is not particularly limited, and may be, for example, circular, elliptical, rectangular, polygonal, or irregular.

[0025] The spunbond nonwoven fabric preferably contains at least one selected from the group consisting of nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, and polystyrene, and more preferably contains polypropylene.

[0026] (pulp fiber web)

[0027] The pulp fiber web preferably contains fibers of at least one softwood bleached kraft pulp selected from the group consisting of radiata pine, slash pine, southern pine, lodgepole pine, spruce, and Douglas fir. The pulp fiber web may contain common pulp fibers such as hardwood bleached kraft pulp (LBKP) in addition to softwood bleached kraft pulp (NBKP). However, the pulp fiber web preferably contains softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP). The ratio of NBKP to LBKP in the pulp fiber is preferably 50:50 to 100:0, more preferably 70:30 to 100:0, even more preferably 90:10 to 100:0, and even more preferably 100:0.

[0028] (Composite nonwoven fabric)

[0029] The proportion of the spunbond nonwoven fabric in the composite nonwoven fabric is 10 to 30% by mass, and the proportion of the pulp fiber web in the composite nonwoven fabric is 70 to 90% by mass. When the proportions are within the above ranges, a composite nonwoven fabric can be obtained that is excellent in water absorption performance and cost and has little color unevenness. The lower limit of the proportion of the spunbond nonwoven fabric is preferably 15% by mass or more, and more preferably 20% by mass. The upper limit of the proportion of the spunbond nonwoven fabric is preferably 27% by mass or less. The lower limit of the proportion of the pulp fiber web is preferably 73% by mass or more. The upper limit of the proportion of the pulp fiber web is preferably 85% by mass or less, and more preferably 80% by mass or less.

[0030] The spunbond nonwoven fabric is colored, but the color is not particularly limited. Such a spunbond nonwoven fabric is preferably colored with a pigment. The pulp fiber web is not colored with a dye. This prevents problems such as the dye easily leaching into the object or solution when wiping off dirt or the like with the sheet 3 made of the composite nonwoven fabric. Note that "colored" may refer to a colored state, and a suitable example is a state in which a pigment is added to the pellets before melt spinning during the production of the spunbond nonwoven fabric, and the nonwoven fabric is colored by spun dyeing.

[0031] When the color of the spunbond nonwoven fabric is expressed in color space (CIELAB), it is preferable that L* is 65 or less, a* is -30 to -10, and b* is -30 or less. It is also preferable that the saturation is C* is 30 or more. When each index of the color space of the spunbond nonwoven fabric is within the above numerical range, it is possible to obtain a composite nonwoven fabric with excellent visibility.

[0032] When the surface of the pulp fiber web in the composite nonwoven fabric is expressed in color space (CIELAB), it is preferable that L* is 80 or less, a* is -20 to -7, and b* is -13 or less. Furthermore, it is preferable that the saturation is C* is 30 or more. When each index of the color space on the surface of the pulp fiber web is within the above numerical range, it is possible to obtain a composite nonwoven fabric with less color unevenness.

[0033] In the composite nonwoven fabric, the color difference ΔE*ab between the pulp fiber web surface and the spunbond nonwoven fabric surface is preferably not more than 10. When the color difference between the pulp fiber web surface and the spunbond nonwoven fabric surface is within the above numerical range, a composite nonwoven fabric with less color unevenness can be obtained.

[0034] In order to impart aesthetic appeal and visibility to the sheet 3, the surface of the composite nonwoven fabric according to this embodiment is further provided with a printed portion 2 printed with ink, and the color difference ΔE*ab between the composite nonwoven fabric and the printed portion 2 is 20 or less. The printed portion 2 is preferably provided on the surface of the spunbond nonwoven fabric of the composite nonwoven fabric. It is more preferable that the color difference between the composite nonwoven fabric and the printed portion 2 be similar colors. From this perspective, the upper limit of the color difference ΔE*ab between the composite nonwoven fabric and the printed portion 2 is preferably 15 or less, more preferably 12 or less. The printed portion 2 may be provided over the entire surface of at least one surface of the sheet 3 (not shown), or, as shown in FIG. 1, a design, character pattern, or the like may be provided at a predetermined interval. By providing the printed portion 2, a composite nonwoven fabric with less color unevenness and excellent aesthetic appeal and visibility can be obtained.

[0035] The ink is not particularly limited and can be appropriately selected taking into consideration the desired application and properties. For example, the ink may contain a colorant, varnish, additives, etc. The colorant in the ink is preferably one containing a pigment. The ink may be either a water-based ink or an oil-based ink. Specific examples of inks include water-based flexographic inks, and an example of a water-based flexographic ink is Brightone XFT-20, manufactured by Sakata Inx Corporation.

[0036] The amount of ink to be applied is not particularly limited, but is preferably 1.0 to 8.0 g / m 2 When ink is applied to the entire surface of one or both sides of the composite nonwoven fabric, the amount of ink applied to one side is preferably 1.0 to 8.0 g / m. 2For example, when printing a design, character pattern, or the like at a predetermined interval, the occupancy rate of the printed portion 2 on the sheet 3 made of the composite nonwoven fabric (the ratio of the total surface area of ​​the printed portion 2 to the total surface area of ​​the sheet 3) is not particularly limited, but the amount of ink applied is preferably 1.0 to 8.0 g / m 2 By setting the amount of ink applied within the above range, cosmetic properties can be effectively ensured, and color transfer to an object or solution when the sheet 3 is used to wipe off dirt or the like can be effectively prevented.

[0037] The color difference evaluation described above can be measured using a color difference meter PF7000 (manufactured by Nippon Denshoku Industries Co., Ltd.). When determining the color difference between two measurement targets, one target and the other target are measured using the color difference meter, and the difference between the two can be taken as the color difference. For example, 16 layers of spunbond nonwoven fabric before integration can be measured, and 4 layers of composite nonwoven fabric after integration can be measured. For composite nonwoven fabric, printed portion 2 and non-printed portion 1 are measured. Non-printed portion 1 can be measured on composite nonwoven fabric before printing with ink, or a portion (non-printed portion 1) without printed portion 2 can be measured on composite nonwoven fabric with printed portion 2.

[0038] The basis weight of the composite nonwoven fabric according to this embodiment is 45 to 85 g / m 2 The lower limit is 50 g / m 2 The upper limit is 75 g / m 2 Less than 65 g / m 2 The following is more preferable. By having the basis weight within the above range, a composite nonwoven fabric with excellent water absorption performance and cost performance can be obtained. The basis weight of the composite nonwoven fabric can be measured in accordance with JIS P 8124.

[0039] The composite nonwoven fabric according to this embodiment has a square root (GMT) of the wet tensile strength in the MD direction (WMDT) and the wet tensile strength in the CD direction (WCDT) according to JIS P 8135, which is 10.0 to 25.0 N / 25 mm. The lower limit is preferably 12.0 N / 25 mm or more. The upper limit is preferably 20.0 N / 25 mm or less, more preferably 16.0 N / 25 mm or less. When the square root (GMT) of the wet tensile strength in the MD direction (WMDT) and the wet tensile strength in the CD direction (WCDT) is within the above range, the composite nonwoven fabric can be tear-resistant when wet and has a soft feel. The wet tensile strengths in each direction can be measured in accordance with JIS P 8135, and the GMT can be calculated as the square root of the product.

[0040] Furthermore, the square root GMT of the product of the dry MD tensile strength DMDT and the dry CD tensile strength DCDT of the composite nonwoven fabric according to JIS P 8113 is preferably 12.0 to 25.0 N / 25 mm. The lower limit is more preferably 13.0 N / 25 mm or more, and even more preferably 14.0 N / 25 mm or more. The upper limit is more preferably 20.0 N / 25 mm or less, and even more preferably 16.0 N / 25 mm or less. When the square root GMT of the product of the dry MD tensile strength DMDT and the dry CD tensile strength DCDT is within the above range, the composite nonwoven fabric can be more resistant to tearing in the wet state and has a softer feel. The tensile strengths in each direction in the dry state can be measured in accordance with JIS P 8113, and GMT can be calculated as the square root of the product.

[0041] The square root GMT of the product of the tensile strength in the MD direction when dry (DMDT) and the tensile strength in the CD direction when dry (DCDT) of the spunbonded nonwoven fabric according to JIS P 8113 is preferably 6.0 to 15.0 N / 25 mm. The lower limit is more preferably 7.0 N / 25 mm or more, and even more preferably 9.0 N / 25 mm or more. The upper limit is more preferably 11.0 N / 25 mm or less. When the square root GMT of the product of the tensile strength in the MD direction when dry (DMDT) and the tensile strength in the CD direction when dry (DCDT) of the spunbonded nonwoven fabric is within the above range, the spunbonded nonwoven fabric can be made to be more resistant to tearing when wet and have a softer feel. The tensile strength in each direction of the spunbonded nonwoven fabric can be measured in the same manner as for the composite nonwoven fabric, using the spunbonded nonwoven fabric at a stage before the pulp fiber web is laminated thereto.

[0042] The water absorption rate of the composite nonwoven fabric according to this embodiment is 5.0 seconds or less. The upper limit is preferably 3.5 seconds or less, more preferably 2.5 seconds or less. By ensuring that the water absorption rate is equal to or less than the above upper limit, the composite nonwoven fabric can have excellent water absorption performance. The water absorption rate is also called drop water absorbency, and is measured in accordance with the drop method specified in JIS L 1907, measuring the time (seconds) from when a 0.1 mL water droplet reaches the surface of a test piece until the specular reflection of the test piece disappears.

[0043] The water absorption (TWA) of the composite nonwoven fabric according to this embodiment is 220 g / m 2 The lower limit is 240 g / m 2 It is preferable that the weight is 270 g / m or more. 2It is more preferable that the water absorption is equal to or greater than the above-mentioned lower limit. By having the water absorption amount equal to or greater than the above-mentioned lower limit, a composite nonwoven fabric with excellent water absorption performance can be obtained. The method for measuring the water absorption amount (TWA: Total Water Absorbance) of the composite nonwoven fabric is to first cut the sheet 3 (composite nonwoven fabric) into a 75 mm x 75 mm square to prepare a test piece, and then measure the dry weight of the test piece. Next, after immersing this test piece in distilled water for 2 minutes, it is hung in a container saturated with water vapor in an extended state (100% RH) with one corner of the test piece as the upper apex, and this apex and the two adjacent corners supported, and left for 30 minutes, after which the weight after draining is measured. For draining, the test piece is cut to 3 mm x 38 mm and used. Finally, from the obtained measured values, the dry weight of the test piece 1 m is measured. 2 Water retention capacity per unit = Water absorption capacity (g / m 2 ) can be obtained.

[0044] Furthermore, the composite nonwoven fabric according to this embodiment preferably contains a chemical solution containing a wet strength agent and an anionic water-soluble polymer, which can effectively prevent pulp fibers (paper powder) from falling off from the pulp fiber web on the composite nonwoven fabric.

[0045] It is preferable to use a polyamide epichlorohydrin (PAE) as the wet strength agent and carboxymethyl cellulose (CMC) as the anionic water-soluble polymer, which can effectively suppress the generation (shedding) of paper dust when wiping with the composite nonwoven fabric, especially when wet.

[0046] The wet strength agent may contain, in addition to polyamide epichlorohydrin (PAE), polyacrylamide (PAM), polyamide epoxy, polyamide polyamine, etc. Furthermore, the anionic water-soluble polymer may contain, in addition to carboxymethyl cellulose (CMC), polyacrylamide (PAM), etc. Examples of polyamide epichlorohydrin wet strength agents that can be used include paper strength agents WS4030, WS4038, WS4027 manufactured by Seiko PMC Co., Ltd., and examples of carboxymethyl cellulose (CMC) that can be used include Sunrose (registered trademark) manufactured by Nippon Paper Industries Co., Ltd.

[0047] The ratio of the amount of anionic water-soluble polymer added to the amount of wet strength agent added is preferably 1.00 or more, more preferably 1.10 or more. When two types of chemicals, a chemical containing a wet strength agent and a chemical containing anionic water-soluble polymer, are added separately, the two types of chemicals come into contact with each other via the first and second adding devices, which can result in the accumulation of dirt in the suction device and dryer. However, by keeping the ratio at or above the above-mentioned lower limit, the chemicals can come into contact with each other during operation, effectively preventing the formation of precipitates due to aggregation, and can effectively prevent the tactile feel of the composite nonwoven fabric from being impaired. This allows for the production of a softer composite nonwoven fabric.

[0048] The anionic water-soluble polymer is preferably added at a rate of 0.50 to 3.50% based on the bone dry weight of the pulp fiber web. The lower limit is more preferably 1.00% or higher. By keeping the rate within the above range, the resulting composite nonwoven fabric can be effectively prevented from becoming too soft, effectively preventing the fibers from getting caught on the uneven surface and paper dust from easily falling off when wiping the uneven surface. Furthermore, the resulting composite nonwoven fabric can be effectively prevented from becoming too stiff and becoming unsuitable for folding and other processes.

[0049] The addition rate of the wet strength agent to the bone dry weight of the pulp fiber web is preferably 2.50% or less. The lower limit is preferably 0.45% or more. The upper limit is more preferably 2.40% or less. By keeping the addition rate within the above range, nozzle clogging during the chemical addition process can be effectively prevented.

[0050] The composite nonwoven fabric according to this embodiment has been described above, but its uses are not limited to a nonwoven wiper for wiping off oil and the like from machinery. Taking advantage of the strength, water absorption, visibility, and other properties of the sheet 3 made of the composite nonwoven fabric, it can also be used as a paper towel or an auxiliary sheet for food preparation.

[0051] <Method of manufacturing composite nonwoven fabric>

[0052] The method for producing the composite nonwoven fabric according to the present embodiment is not particularly limited, and the fabric can be produced by a known production method. Such a production method can include, for example, the steps of (1) producing the composite nonwoven fabric, (2) cutting, and (3) packaging, but other steps may be added.

[0053] In the production of the composite nonwoven fabric (1), the method of laminating a pulp fiber web onto a colored spunbond nonwoven fabric and then integrating them may be a common method such as spunlace, but from the viewpoint of water absorption and abrasion resistance, hydroentanglement is preferred. The integration process by hydroentanglement is described in detail, for example, in Japanese Patent No. 6758116. Composite nonwoven fabrics integrated by hydroentanglement effectively combine wet strength, water absorption, and liquid retention, and are therefore suitable for a variety of applications, such as the surfaces of machinery, equipment, and utensils used in food production, processing, treatment, and cooking, or for wiping workers' hands.

[0054] Furthermore, in the production of the composite nonwoven fabric (1), the forming section is preferably an airlaid method. Compared to wet-laid (pulp fiber sheet) methods, the airlaid method has fewer bonds between pulps. Therefore, the pulp fibers are effectively dispersed during hydroentangling and spunlace processes, and the spunbond layer is easily exposed on the surface, effectively suppressing the occurrence of color unevenness in the composite nonwoven fabric. Furthermore, immediately after leaving the hydroentangling device, the composite nonwoven fabric is in a wet state, and the bonds between the pulp fibers are not yet fully established. Therefore, after hydroentangling, it is preferable to perform a dehydration process to suction and remove any remaining moisture from the pulp fiber web, followed by a drying process to complete the production of the composite nonwoven fabric.

[0055] Furthermore, in the production of the composite nonwoven fabric (1), it is preferable to include an addition step in which a pulp fiber web is laminated onto a colored spunbond nonwoven fabric to integrate them, and then a dehydration treatment is performed to adjust the moisture content of the composite nonwoven fabric, followed by adding a chemical solution containing a wet strength agent and an anionic water-soluble polymer to the pulp fiber web. Adding the chemical solution to the composite nonwoven fabric after a dehydration treatment to adjust the moisture content of the composite nonwoven fabric can more uniformly fix the wet strength agent and the anionic water-soluble polymer, effectively ensuring the yield of the composite nonwoven fabric. It is also possible to produce a composite nonwoven fabric that exhibits strength more efficiently. The addition step preferably involves adding the chemical solution to the pulp fiber web by spraying. Adding the chemical solution to the pulp fiber web by spraying effectively suppresses the generation of paper dust in the composite nonwoven fabric produced and effectively maintains a soft feel. The conveying speed of the pulp fiber web during the addition of the chemical solution is preferably 100 m / min or more and 300 m / min or less. It is also preferable to spray the chemical solution in two separate steps. When adding the chemical solution in two separate steps, a large amount of the chemical solution will flow out without settling, but the chemical solution is dispersed, reducing nozzle clogging and allowing for efficient production of a composite nonwoven fabric. The chemical solution to be added may be a mixture of a wet strength agent and an anionic water-soluble polymer, or it may be two separate chemical solutions containing the wet strength agent and the anionic water-soluble polymer without mixing them. When two chemical solutions are used, it is preferable that, in the above-mentioned two-step spraying, one chemical solution containing the wet strength agent is added to the pulp fiber web, and then the other chemical solution containing the anionic water-soluble polymer is added to the pulp fiber web within two seconds. By setting the addition interval to within two seconds, the two types of chemical solutions can be effectively retained within the nonwoven fabric.

[0056] In (1), the dryer section is not particularly limited, but a through-air dryer is preferred.

[0057] In addition, the composite nonwoven fabric according to this embodiment is preferably subjected to a printing step in which ink is printed on the entire surface or at least a portion of at least one side of the composite nonwoven fabric before or after the dryer section. The printing step is preferably flexographic printing.

[0058] In the packaging of (3), the composite nonwoven fabric may be packaged, for example, by stacking flat sheets or by winding it up in a roll. [Example]

[0059] The present invention will be explained in more detail with reference to the following examples and comparative examples, but the present invention is not limited to these examples in any way.

[0060] <Examples 1 to 10 and Comparative Examples 1 to 15>

[0061] Composite nonwoven fabrics of Examples 1 to 10 and Comparative Examples 1 to 15 were produced under the conditions shown in Tables 1 and 2, and were tested and evaluated as follows. In all Examples and Comparative Examples, a pulp fiber web containing at least one type of softwood bleached kraft pulp selected from the group consisting of Radiata pine, slash pine, Southern pine, lodgepole pine, spruce, and Douglas fir was laminated on a spunbond nonwoven fabric containing polypropylene, and the resulting composite nonwoven fabric was integrated by hydroentangling to form a base fabric. The colored spunbond nonwoven fabric used was one colored by adding a pigment to the pellets prior to melt spinning. Furthermore, a flexographically printed area was partially formed on the surface of the spunbond nonwoven fabric side of some of the composite nonwoven fabrics in each Example and Comparative Example using an aqueous flexographic ink (product name "Brighttone XFT-20" manufactured by Sakata Inx Corporation) by flexographic printing.

[0062] (test)

[0063] (Wet Geometric Mean Strength) The geometric mean strength of the wet composite nonwoven fabric was determined in accordance with JIS P 8135 by measuring the tensile strength DMDT in the MD direction (the direction in which the composite nonwoven fabric is manufactured) and the tensile strength DCDT in the CD direction (the direction perpendicular to the direction in which the composite nonwoven fabric is manufactured) when wet, and calculating the geometric mean strength (GMT) as the square root of the product of these values.

[0064] (Water absorption rate) The water absorption rate of the composite nonwoven fabric was measured in accordance with the water absorption rate test specified in JIS L 1907, measuring the time (seconds) from when a 0.1 mL water droplet reached the surface of the test piece until the specular reflection of the test piece disappeared.

[0065] (Water absorption amount (TWA)) The composite nonwoven fabric was cut into a 75mm x 75mm square to prepare a test piece, and its dry weight was measured. Next, this test piece was immersed in distilled water for 2 minutes, and then hung in a steam-saturated container in a stretched state (100% RH) with one corner of the test piece positioned at the top, and this top and the two adjacent corners were supported, and the test piece was left for 30 minutes, after which the weight was measured after draining. Note that the test piece was cut into 3mm x 38mm and used for draining. The measured value was then measured for 1m of the test piece. 2 Water retention capacity per unit (g / m 2 ) was converted.

[0066] (geometric mean strength when dry) The geometric mean strength of the dry composite nonwoven fabric and the dry spunbond nonwoven fabric was determined in accordance with JIS P 8113 by measuring the tensile strength in the MD direction (DMDT) and the tensile strength in the CD direction (DCDT) of each fabric in the dry state, and calculating the geometric mean strength (GMT) as the square root of the product of these values.

[0067] (evaluation)

[0068] 1. Usability (ease of wiping) The ease of wiping off dirt and other stains using the composite nonwoven fabric was evaluated on a 5-point scale. The evaluation was based on a standard of "3" for a composite nonwoven fabric that had no problems with flexibility or water absorption and was easy to wipe off, with a "4" for slightly better, a "5" for excellent, a "2" for slightly worse, and a "1" for poor.

[0069] 2.Water absorption performance The water absorption performance when wiping away moisture with the composite nonwoven fabric was evaluated (sensory) on a 5-point scale. The evaluation was based on a standard of "3" for water absorption performance (water absorption speed, water absorption amount) when using the composite nonwoven fabric, a "4" for slightly better, a "5" for excellent, a "2" for slightly worse, and a "1" for poor.

[0070] 3. Cosmetic The composite nonwoven fabric sheet was visually evaluated for color unevenness and appearance. The evaluation was based on a standard of "3" for a sheet with no problem with color unevenness or appearance, "4" for slightly better, "5" for better, "2" for slightly worse, and "1" for worse.

[0071] 4. Color transfer (hot water 100℃) The composite nonwoven fabric sheet was immersed in hot water (100°C) for 10 minutes, and visually inspected to see if there was any discoloration in the hot water. The evaluation was based on whether the color did not transfer to the hot water, and whether the color did transfer to the hot water, and the evaluation was based on whether the color did transfer to the hot water.

[0072] 5. Color migration (70% ethanol) The composite nonwoven fabric sheet was sandwiched between filter papers and immersed in 70% ethanol for 10 minutes. The immersed sheet was removed and left for 24 hours. Then, it was visually confirmed whether or not there was any color transfer to the filter paper. The evaluation was performed with a "good" if no color transfer to the filter paper, and with a "bad" if there was any color transfer to the filter paper.

[0073] 6. Color transfer (grain vinegar) The composite nonwoven fabric sheet was sandwiched between filter papers and immersed in grain vinegar (manufactured by Mitsukan Co., Ltd.) for 10 minutes. The immersed sheet was removed and left for 24 hours. Then, it was visually confirmed whether or not there was any color transfer to the filter paper. The evaluation was performed with "Good" when no color transfer to the filter paper was observed, and "Poor" when color transfer to the filter paper was observed.

[0074] 7.Wet tear strength The strength of the sheet was evaluated (sensory) by pulling on it after wetting it with water. A tear strength that was acceptable for use was given a standard rating of "3," while a slightly better rating was given a rating of "4," an excellent rating of "5," a slightly worse rating of "2," and an inferior rating of "1."

[0075] 8. Visibility The sheet was placed on white drawing paper and the ease of distinguishing it from the drawing paper was evaluated (sensory). The evaluation was given a "good" if the colored sheet could be immediately distinguished from the white drawing paper, and an "unclear" if it could not be immediately distinguished from the white drawing paper.

[0076] The conditions and evaluation results for each example are shown in Table 1, and the conditions and evaluation results for each comparative example are shown in Table 2. Note that products with an evaluation score of 3 or higher are acceptable for use as products.

[0077] [Table 1]

[0078] [Table 2]

[0079] From the above, it was at least confirmed that the composite nonwoven fabric of this example maintained good usability, water absorption performance, cosmetic properties, wet tensile strength, and visibility, and that color migration was sufficiently suppressed. [Explanation of symbols]

[0080] 1 Non-printed part 2 Printing Department 3 seats

Claims

1. It is a composite nonwoven fabric that is integrated by laminating a pulp fiber web on a spunbond nonwoven fabric. a pulp fiber web that is not colored with dyes; a colored spunbond nonwoven fabric; The surface of the composite nonwoven fabric has a printed portion printed with ink, the color difference ΔE*ab between the composite nonwoven fabric and the printed portion is 20 or less; The composite nonwoven fabric has a basis weight of 45 to 85 g / m ２ and The ratio of the spunbond nonwoven fabric contained in the composite nonwoven fabric is 10 to 30% by mass, The proportion of the pulp fiber web contained in the composite nonwoven fabric is 70 to 90% by mass, The square root (GMT) of the product of the wet tensile strength (WMDT) in the MD direction and the wet tensile strength (WCDT) in the CD direction according to JIS P 8135 is 10.0 to 25.0 N / 25 mm; The water absorption rate is 5.0 seconds or less, Water absorption (T.W.A.) is 220 g / m ２ That's it, composite nonwoven fabric.

2. The composite nonwoven fabric according to JIS P 8113 has a square root (GMT) of the product of the tensile strength (DMDT) in the MD direction when dry and the tensile strength (DCDT) in the CD direction when dry, in a range of 12.0 to 25.0 N / 25 mm.

3. The spunbond nonwoven fabric has a square root (GMT) of the product of the tensile strength (DMDT) in the MD direction when dry and the tensile strength (DCDT) in the CD direction when dry, according to JIS P 8113, of 6.0 to 15.0 N / 25 mm.

4. The spunbond nonwoven fabric includes a plurality of fusion points that bond spun resin fibers together, The area of ​​each of the fusion points is 0.10 to 0.50 mm ２ and the area ratio of the fusion-bonded points per unit area in the spunbonded nonwoven fabric is 7 to 20%; The number of fusion points per unit area in the spunbond nonwoven fabric is 10 to 150 / cm ２ and The spunbond nonwoven fabric contains at least one selected from the group consisting of nylon, vinylon, polyester, acrylic, polyethylene, polypropylene, and polystyrene, 3. The composite nonwoven fabric according to claim 1, wherein the pulp fiber web contains fibers of at least one type of bleached softwood kraft pulp selected from the group consisting of radiata pine, slash pine, southern pine, lodgepole pine, spruce, and Douglas fir.

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