Wet tissue and production method of base cloth for wet tissue

Abstract

To provide a wet tissue and a production method of a base cloth for wet tissue, the wet tissue being excellent in liquid holding property in use in a wet state in which the wet tissue is impregnated with chemical liquid, and being excellent in wiping property of liquid state pollution, especially even without the embossing processing.SOLUTION: There is provided a wet tissue in which, in a nonwoven cloth sheet including at least a cellulose-derived fiber, is impregnated with chemical liquid. In the wet tissue, stress required for extending by 5%, the wet tissue in a MD direction is 0.75 MPa or greater and 4.00 MPa or smaller, stress required for extending by 5%, the wet tissue in a CD direction is 0.08 MPa or greater and 0.90 MPa or smaller. There is also provided a production method of a base cloth for wet tissue.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a wet tissue using a nonwoven fabric sheet and a method for producing a wet tissue base fabric. [Background technology]

[0002] Wet tissues, which are made of paper or nonwoven fabric impregnated with a chemical solution, are well known as products for wiping the body, including the hands, and for wiping off water and dirt.

[0003] However, in recent years, wet tissues made of so-called composite nonwoven fabrics, in which pulp fibers and synthetic fibers are laminated or mixed, have also been sold.

[0004] The characteristics of the composite nonwoven fabrics used in wet tissues include liquid retention, ease of use (resistance to curling), water absorption, and the ability to wipe off liquid stains.

[0005] In addition, one method for producing composite nonwoven fabrics is to hydroentangle 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, to produce a sheet that combines strength and absorbency. In this case, the pulp fiber web can be supplied by a general wet papermaking method or dry airlaid, or can be supplied as a sheet produced by wet papermaking.

[0006] As a prior art document for such wet tissues, for example, Patent Document 1 describes a wet tissue made of a composite nonwoven fabric obtained by hydroentangling a spunbond nonwoven fabric and a pulp fiber web, in which the pulp fiber web has a basis weight of 15 g / m 2 The above and spunbond nonwoven fabric has a basis weight of 8 g / m 2The wet tissue is characterized in that the mass composition ratio of spunbond nonwoven fabric / pulp fiber web is 10 / 90-50 / 50 (wt%), the fiber diameter of the resin fibers constituting the spunbond nonwoven fabric is 0.6-5.6 dtex, the spunbond nonwoven fabric is formed so that the elongation in the lateral direction when a load of 0.5 N is applied in the lateral direction perpendicular to the fiber flow direction is 5% or less, and further, the wet Taber test specified by JIS has an abrasion resistance of 20 times or more.It is also disclosed that the composite nonwoven fabric in which the pulp fiber web is laminated on the spunbond nonwoven fabric is characterized in that the pulp fiber web side is embossed. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2020-048680 A Summary of the Invention [Problem to be solved by the invention]

[0008] Conventional wet tissues often fail to completely wipe away liquid stains when wiping them off, with some of the stain remaining behind. There is therefore a demand for wet tissues that can not only simply wipe away liquid stains, but also cleanly wipe away all of the stains without leaving any behind.

[0009] Conventional wet tissues such as those described in Patent Document 1 have improved wiping properties against liquid stains by embossing the sheet. However, in some cases, it is preferable not to emboss the sheet in terms of material or cost, and wet tissues without such embossing have inferior wiping properties against liquid stains. Furthermore, while it is possible to improve the ability to wipe off liquid stains by improving the water absorption of wet tissues, this then results in the problem of poor liquid retention, as the liquid becomes more likely to evaporate or flow out of the sheet.

[0010] The present invention has been made in consideration of the above circumstances, and has an object to provide a wet tissue and a method for producing a base fabric for wet tissues that have excellent liquid retention properties when used in a wet state impregnated with a chemical solution, and that are particularly excellent in wiping off liquid stains even without embossing. [Means for solving the problem]

[0011] The inventors conducted extensive research and found that, in a wet tissue comprising a nonwoven fabric sheet containing at least cellulose-derived fibers and impregnated with a chemical solution, by setting the stress required to stretch the wet tissue by 5% in the MD direction and the stress required to stretch the wet tissue by 5% in the CD direction both within a predetermined numerical range, the wet tissue has excellent liquid retention properties when used in a wet state impregnated with the chemical solution, and even if not embossed, has particularly excellent wiping properties for liquid stains, and thus completed the present invention. That is, the present invention provides the following.

[0012] (1) A first aspect of the present invention is a wet tissue comprising a nonwoven fabric sheet containing at least cellulose-derived fibers impregnated with a medicinal solution, the wet tissue being characterized in that the stress required to stretch the wet tissue by 5% in the MD direction is 0.75 MPa or more and 4.00 MPa or less, and the stress required to stretch the wet tissue by 5% in the CD direction is 0.08 MPa or more and 0.90 MPa or less.

[0013] (2) A second aspect of the present invention is the wet tissue according to (1), characterized in that the cellulose fibers contained in the nonwoven fabric sheet are pulp fibers, the nonwoven fabric sheet is a pulp-containing composite nonwoven fabric having a pulp fiber content of 70% by weight or more and 90% by weight or less, and the pulp-containing composite nonwoven fabric is a composite nonwoven fabric obtained by hydroentangling a spunbond nonwoven fabric and a pulp fiber web.

[0014] (3) A third aspect of the present invention is the wet tissue described in (1), characterized in that the water absorption per unit weight of the nonwoven fabric sheet in an absolutely dry state not impregnated with the medicinal solution is 4.0 g / g or more and 8.0 g / g or less, and the impregnation ratio of the medicinal solution to the nonwoven fabric sheet is 150% or more and 320% or less.

[0015] (4) A fourth aspect of the present invention is the wet tissue according to (1), wherein the nonwoven fabric sheet has a basis weight of 36 g / m in an absolutely dry state in which the drug solution is not impregnated. 2 More than 110g / m 2 It is characterized in that:

[0016] (5) A fifth aspect of the present invention is a method for producing a wet tissue base fabric as described in (2), characterized in that the method for forming the pulp fiber web is an airlaid method, and the method includes at least a hydroentanglement step of hydroentanglement-treating the spunbond nonwoven fabric and the pulp fiber web. Effect of the Invention

[0017] According to the present invention, it is possible to provide wet tissues and a method for producing a base fabric for wet tissues which have excellent liquid retention properties when used in a wet state impregnated with a chemical solution, and which are particularly excellent in wiping off liquid stains even without embossing. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0018] Hereinafter, an embodiment for carrying out the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. The 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. In addition, the MD direction of the wet tissue is the machine direction in which the nonwoven fabric sheet is made, and the CD direction is the cross direction perpendicular to the machine direction.

[0019] <Wet tissue> The wet tissue according to the present embodiment is a nonwoven fabric sheet containing at least cellulose-derived fibers impregnated with a medicinal solution. The nonwoven fabric sheet will be described in detail below. The liquid medicine to be impregnated into the sheet may contain alcohol, a moisturizer, a preservative, an antibacterial agent, a stabilizer, and the like, which are generally used in wet tissues.

[0020] In this case, the impregnation ratio of the chemical solution to the nonwoven fabric sheet is preferably 150% or more and 320% or less. If the impregnation ratio is less than 150% or more than 320%, the wet tissue is inferior in wiping off liquid stains. The impregnation ratio is more preferably 200% or more and 300% or less. The impregnation ratio is calculated by the amount of water (g) contained in the nonwoven fabric sheet ÷ the weight (g) of the nonwoven fabric sheet when completely dry × 100 (%).

[0021] In addition, the stress required to stretch the wet tissue 5% in the MD direction is 0.75 MPa to 4.00 MPa, and the stress required to stretch it 5% in the CD direction is 0.08 MPa to 0.90 MPa. If the stress required to stretch it 5% in the MD direction is less than 0.75 MPa or the stress required to stretch it 5% in the CD direction is less than 0.08 MPa, the sheet is prone to curling and has poor wiping properties for liquid stains. If the stress required to stretch it 5% in the MD direction exceeds 4.0 MPa or the stress required to stretch it 5% in the CD direction exceeds 0.90 MPa, the liquid retention of the chemical solution and the flexibility of the sheet are poor, resulting in poor wiping properties for liquid stains. The stress required to stretch the wet tissue by 5% in the MD direction is preferably 1.00 MPa or more and 2.00 MPa or less, and the stress required to stretch the wet tissue by 5% in the CD direction is preferably 0.10 MPa or more and 0.25 MPa or less.

[0022] The stress is determined by soaking a sample cut to a width of 25 mm in pure water, lightly removing the moisture, and then pulling it at a speed of 20 mm / min using a Tensilon testing machine, measuring the load (MPa) for a 5% elongation. The elongation of the wet tissue (nonwoven sheet) is adjusted to be within the above range depending on the quality of the nonwoven fabric base material (basis weight, type of resin), the content of cellulose-derived fibers, and the tension, speed, and heat calendar or heat embossing processing during operation (manufacturing).

[0023] (Nonwoven fabric sheet) The nonwoven fabric sheet used in the wet tissue according to this embodiment contains at least fibers derived from cellulose, and preferably the cellulose fibers contained in the nonwoven fabric sheet are pulp fibers, and the nonwoven fabric sheet is a pulp-containing composite nonwoven fabric having a pulp fiber content of 70% by weight to 90% by weight. By having the pulp fiber content within the above numerical range, the wet tissue can be made to have excellent liquid retention and liquid stain wiping properties even when the nonwoven fabric sheet is impregnated with a chemical solution. The pulp fiber content is preferably 75% by weight or more and 85% by weight or less.

[0024] The pulp-containing composite nonwoven fabric is preferably prepared by hydroentangling a spunbond nonwoven fabric and a pulp fiber web.

[0025] Spunbond nonwoven fabrics are made of polypropylene and contain primarily polypropylene fibers, but may also contain one or more synthetic fibers selected from the group consisting of nylon, vinylon, polyester, acrylic, polyethylene, and polystyrene.

[0026] The pulp fiber web preferably comprises one or more bleached softwood kraft pulp (NBKP) fibers selected from the group consisting of radiata pine, slash pine, southern pine, lodgepole pine, spruce, and Douglas fir. In addition to softwood bleached kraft pulp (NBKP), general pulp fibers such as hardwood bleached kraft pulp (LBKP) may also be included, but it is preferable to include softwood bleached kraft pulp (NBKP) and hardwood bleached kraft pulp (LBKP). The content ratio of NBKP and LBKP in the pulp fibers is preferably 50:50 or more and 100:0 or less, more preferably 70:30 or more and 100:0 or less, even more preferably 90:10 or more and 100:0 or less, and most preferably 100:0.

[0027] The basis weight of the nonwoven fabric sheet in an absolutely dry state without any chemical solution is 36 g / m 2 More than 110g / m 2 By having the basis weight within the above range, the wet tissue can have excellent liquid retention and is particularly excellent in wiping off liquid stains. The basis weight of the nonwoven fabric sheet is 40 g / m 2 More than 105g / m 2 It is more preferable that the basis weight is equal to or less than 100 g / m. The basis weight is measured in accordance with JIS P 8124.

[0028] In addition, the water absorption per unit weight of the nonwoven fabric sheet in an absolutely dry state, in which no drug solution is impregnated, is preferably 4.0 g / g or more and 8.0 g / g or less. If the water absorption is less than 4.0 g / g, the wet tissue will have poor liquid retention. If the water absorption is more than 8.0 g / g, the wet tissue will have poor wiping properties for liquid stains. It is more preferable that the water absorption per unit weight is 4.5 g / g or more and 7.5 g / g or less. The water absorption per unit weight (also called Total Water Absorbance (TWA)) is measured by first cutting a nonwoven sheet into a square test piece of 76 x 76 mm, and measuring the dry mass (W1). After that, the test piece is immersed in distilled water for 2 minutes, and then one corner of the test piece is placed at the top, and the top and two adjacent corners are supported and hung in an extended state (RH 100%), and the mass (W2) is measured after leaving it for 30 minutes. The value of (W2-W1) is then calculated, and this value is converted to the water retention per gram of sample (g / g), which is the water absorption per unit weight (TWA).

[0029] The water absorption rate of the nonwoven fabric sheet in an absolutely dry state (not impregnated with any chemical solution) is preferably 3 seconds or less. By having the water absorption rate within the above range, the wet tissue can be made to be particularly excellent in wiping off liquid stains. The water absorption rate is calculated by measuring the number of seconds it takes for 100 μL of water to completely disappear when a completely dry nonwoven fabric sheet is soaked in water.

[0030] The nonwoven fabric sheet preferably has a tensile strength in the MD direction when dry (DMDT) of 1200 gf / 25 mm or more and 7500 gf / 25 mm or less, and a tensile strength in the CD direction when dry (DCDT) of 600 gf / 25 mm or more and 5000 gf / 25 mm or less, based on JIS P 8113. By having the DMDT and DCDT within the above numerical ranges, the wet tissue can be made to have particularly excellent wiping properties for liquid stains.

[0031] The tensile strength in the MD direction when dry is more preferably 1800 gf / 25 mm or more and 5000 gf / 25 mm or less, and the tensile strength in the CD direction when dry is more preferably 800 gf / 25 mm or more and 3000 gf / 25 mm or less. The tensile strength in each direction is measured by a tensile tester using a test piece with a width of 25 mm cut out from the nonwoven fabric sheet. The measurement conditions are a chuck distance of 100 mm, a tensile speed of 300 mm / min, and an average value of four measurements (n=4).

[0032] <Wet tissue manufacturing method> The wet tissue according to this embodiment can be produced by the same process as that for ordinary wet tissue products. Specifically, the wet tissue can be obtained by the processes of (1) producing a wet tissue base fabric, (2) cutting, and (3) folding, laminating, and impregnating with a chemical solution. The timing of the chemical impregnation may be before or after lamination, or lamination and impregnation may be performed simultaneously. It is also preferable not to perform embossing.

[0033] In addition, in the case of using a composite nonwoven fabric obtained by hydroentangling a spunbonded nonwoven fabric and a pulp fiber web as the raw material of the pulp-containing composite nonwoven fabric in the production of (1) a base fabric for wet tissues, the method of laminating and integrating the pulp fiber web on the spunbonded nonwoven fabric may be a general method such as a spunlace method, but from the viewpoint of liquid retention and wiping off liquid stains, hydroentangling is preferable as described above. The integration process by hydroentangling is described in detail, for example, in Japanese Patent No. 6758116. Furthermore, as a method for forming a web from cellulose-derived fibers (pulp fibers), the air-laid method is preferred from the viewpoint of water absorption speed. If a wet method is used for forming a web, the resulting wet tissue has a poor water absorption speed.

[0034] The wet tissue produced by the above process is packaged in a package and then shipped as a product. The package is not particularly limited as long as it is a water-impermeable, flexible plastic film package or a hermetically sealed plastic container that is commonly used for wet tissue products.

[0035] As described above, according to the present embodiment, it is possible to provide wet tissues that have excellent liquid retention properties when used in a wet state impregnated with a chemical solution, and that are particularly excellent in wiping off liquid stains even without embossing. EXAMPLES

[0036] The present invention will be described in more detail with reference to the following examples and comparative examples, but the present invention is not limited to the following examples in any way.

[0037] Composite nonwoven fabrics of Examples 1 to 5 and Comparative Examples 1 to 6 were produced under the conditions shown in Table 1, and the following evaluations were carried out. Measurements of each parameter other than the following evaluations were carried out according to the standards or measurement methods described above. All measurements according to the standards or measurement methods described above were carried out indoors at a temperature of 23°C and a humidity of 50% RH.

[0038] (Chemical liquid retention) The liquid retention of the wet tissues was evaluated according to the following criteria based on the amount of water absorbed per unit weight. ◎: Water absorption per unit weight is 5.0g / g or more and less than 8.0g / g ○: Water absorption per unit weight is 4.0 g / g or more and less than 5.0 g / g ×: Water absorption per unit weight is less than 4.0 g / g

[0039] (Easy to use when wiping (less likely to curl)) The nonwoven fabric sheet was moistened with pure water at the impregnation ratio shown in Table 1, and the nonwoven fabric sheet was reciprocated 10 times using a fastness tester, and the twisting and displacement of the nonwoven fabric sheet were visually evaluated. The nonwoven fabric sheet was set so that the wiping direction was the CD direction. ◎: Creases and misalignments are barely noticeable ○: There is some wrinkling or misalignment, but it is not noticeable. ×: Creases and misalignment are noticeable

[0040] (Liquid absorption during wet towel manufacturing) The liquid absorbency of the wet tissues produced as hand towels was evaluated according to the following criteria based on the water absorption rate. ◎: Water absorption speed is less than 3 seconds ×: Water absorption speed is 3 seconds or more

[0041] (Liquid dirt removal) A 100mm x 100mm nonwoven fabric sheet was moistened with 65% ethanol at a specified impregnation ratio, and the wiping ability was evaluated visually when wiping off simulated stains. The simulated stains were mainly edible oil, and were colored to show the degree of stain removal. Specifically, 0.25 ml of the stain was dropped onto the nonwoven sheet moistened with the chemical solution, and then a 59 g weight was placed on top of it, after which it was dragged 25 cm for 5 seconds. After that, the degree of remaining stain was visually evaluated. ◎: Almost no dirt remained ○: There was a small amount of dirt remaining, but it was not a problem. ×: Most of the dirt remained

[0042] (comprehensive evaluation) A comprehensive evaluation was performed on the wet tissues of each Example and Comparative Example based on the above-mentioned evaluations. A comprehensive evaluation of 2 points or more was deemed to be of acceptable quality. 5 points: All evaluation results are excellent 4 points: The liquid retention of the drug is slightly inferior, but otherwise excellent 3 points: Slightly inferior in terms of liquid dirt removal, but excellent in other areas 2 points: The ability to remove liquid dirt and the resistance to curling are somewhat inferior, but the required quality level is met. 1 point: Not suitable for solving the current problem (marked with an X)

[0043] Table 1 shows the conditions and evaluation results for each of the examples and comparative examples. [Table 1]

[0044] From the above, it was confirmed that this embodiment can provide wet tissues that have excellent liquid retention when used in a wet state impregnated with a chemical solution, and that are particularly excellent in wiping off liquid stains, even if the tissues are not embossed.

Claims

1. The wet tissue is a nonwoven fabric sheet containing at least cellulose-derived fibers impregnated with a medicinal solution, A wet tissue, characterized in that the stress required to stretch the wet tissue by 5% in the MD direction is 0.75 MPa or more and 4.00 MPa or less, and the stress required to stretch the wet tissue by 5% in the CD direction is 0.08 MPa or more and 0.90 MPa or less.

2. The cellulose fibers contained in the nonwoven fabric sheet are pulp fibers, The nonwoven fabric sheet is a pulp-containing composite nonwoven fabric having a pulp fiber content of 70% by weight or more and 90% by weight or less, 2. The wet tissue according to claim 1, wherein the pulp-containing composite nonwoven fabric is a composite nonwoven fabric obtained by hydroentangling a spunbond nonwoven fabric and a pulp fiber web.

3. the water absorption amount per unit weight of the nonwoven fabric sheet in an absolutely dry state not impregnated with the drug solution is 4.0 g / g or more and 8.0 g / g or less; 2. The wet tissue according to claim 1, wherein an impregnation rate of the nonwoven fabric sheet with the chemical solution is 150% or more and 320% or less.

4. The nonwoven fabric sheet has a basis weight of 36 g / m in an absolutely dry state without being impregnated with the chemical solution. ２ 110g / m or more ２ 2. The wet tissue according to claim 1, characterized in that:

5. A method for producing a wet tissue base fabric used as a raw roll of the wet tissue according to claim 2, The method for forming the pulp fiber web is an airlaid method, The method for producing a wet tissue base fabric is characterized by comprising at least a hydroentanglement step of hydroentanglement-treating the spunbond nonwoven fabric and the pulp fiber web.

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