JP2024046997A - Wet tissue - Google Patents

Abstract

[Problem] To provide wet tissues that use paper as a sheet impregnated with a chemical solution, and that have excellent texture and compactness, and are resistant to tearing, even when stacked in a state folded six times or more. [Solution] To provide wet tissues in which a paper sheet containing at least pulp fiber is impregnated with a chemical solution and stacked in a state folded six times or more, the wet tissues being characterized in that the WC (compression work) of the sheet when compressed with a KES compression tester is 0.15 gf cm/cm2 or more and 0.65 gf cm/cm2 or less, and the tensile strength of the sheet when wet is 2.2 N/25 mm or more and 3.8 N/25 mm or less. [Selected Figure] Figure 1

Description

The present invention relates to wet tissues made of paper sheets impregnated with a medicinal liquid.

Wet tissue products are generally manufactured by impregnating a sheet of nonwoven fabric or paper with a chemical solution.

Wet tissue packaging and containers come in a variety of types, including bottle type, pillow type, and handy type. In particular, the market for so-called handy types, which are compact and easy to carry, is expanding due to the increasing frequency of wiping hands and disinfecting while out and about.

Many handy types are made up of folded sheets stacked together so that they can be taken out one by one without popping up, and are folded in a way that makes them compact and easy to take out.

For example, Patent Document 1, which is a document on such handy type wet tissues, discloses an ultra-mini wet tissue package in which an opening is provided on a packaging bag and a sheet-like opening and closing lid is provided on the opening, the opening has a width of 15-30 mm and a length of 25-50 mm, both sides of the opening in the length direction are arc-shaped, the wet tissue stack is made by folding a number of independent single tissues and then stacking them on top of each other in the thickness direction, and the folded tissue body has a length of 70-80 mm, a width of 32.5-37.5 mm, and a height of 6-20 mm. It also discloses that the ultra-mini wet tissue package has a length of 83-105 mm, a width of 38.5-41 mm, and a height of 8-22 mm, and that when used, the sheet-like opening and closing lid is opened and the wet tissue is pulled out from within the gap in the packaging bag, and a peeling stopper is provided on the opening and closing lid to prevent the sheet-like opening and closing lid from peeling off from the packaging bag.

Patent Document 2 discloses a wet sheet package in which multiple wet sheets are stored in a stack inside a package that includes a bag-shaped bag body with an opening and a lid that covers the opening in an openable and closable manner, and the wet sheets are taken out one by one through the opening for use. The wet sheet package has a tab portion formed by folding the wet sheet in the lengthwise or widthwise direction on the upper surface side at a position facing the opening when the wet sheet is stored in the package, and a folded portion formed by folding the ends in the lengthwise or widthwise direction on the side where the tab portion is not formed downward in an S-shape or Z-shape.

Utility Model Registration No. 3220555 JP 2013-075674 A

Here, due to the recent increase in environmental awareness, there is a demand for paper wet tissues that do not use plastic in the sheets. In particular, for products such as handy types that are used when going out, there is an increasing demand for paper sheets because of the advantages of easy separation after use and biodegradability.
However, when paper is used for handy type sheets, the sheets have many creases in order to be folded compactly, which poses the problem that the sheets are easily torn at the creases.

If the folding process is loosened to prevent creases, the paper cannot be stacked compactly, which reduces portability. Also, if the paper is made stronger to prevent tearing, the texture deteriorates.
Furthermore, when paper is used for the sheets, the sheets tend to stick together, making it difficult to remove the sheets one by one when removing them, and they tend to come out in a stuck state.

When using paper for wet tissue sheets to make handy products, it was difficult to create wet tissues that had a good texture and were compact, and were also difficult to tear.

The present invention was made in consideration of these circumstances, and aims to provide wet tissues that use paper for the sheets that are impregnated with the drug solution, and that have excellent texture and compactness, and are difficult to tear, even when folded six or more times and stacked.

The inventors conducted extensive research and found that, in wet tissues formed by impregnating paper sheets containing at least pulp fibers with a chemical solution and folding the sheets six or more times to form stacked sheets, the WC (compression work) of the sheets when compressed using a KES compression tester and the tensile strength when wet are each within a specified range, thereby making it possible to produce wet tissues that have excellent texture and compactness and are not easily torn, thereby completing the present invention. That is, the present invention provides the following.

(1) A first aspect of the present invention is a wet tissue which is formed by impregnating a paper sheet containing at least pulp fibers with a chemical solution and laminating the sheet in a state of being folded in six or more folds, the wet tissue being characterized in that the WC (compression work) of the sheet when compressed with a KES compression tester is 0.15 gf cm/cm2 ^or more and 0.65 gf cm/ ^cm2 or less, and the tensile strength of the sheet when wet is 2.2 N/25 mm or more and 3.8 N/25 mm or less.

(2) A second aspect of the present invention is the wet tissue according to (1), characterized in that, when a load of 50 gf/ ^cm2 is applied to the sheet using a KES compression tester, T _m is the thickness of the sheet, and a load of 0.5 gf/ ^cm2 is applied to the sheet, T ₀ is the thickness of the sheet, and (T ₀ -T _m )/T ₀ is 0.40 or more.

(3) A third aspect of the present invention is the wet tissue according to (1), characterized in that the thickness _Tm of the sheet when a load of 50 gf/ ^cm2 is applied to the sheet using a KES compression tester is 160 μm or more and 440 μm or less.

(4) The fourth aspect of the present invention is the wet tissue described in (1), characterized in that the sheet has an uneven pattern on the surface derived from a papermaking machine, and the height of the concaves and convexities combined in the unevenness is 100 μm or more and 300 μm or less.

According to the present invention, it is possible to provide wet tissues that are excellent in texture and compactness, and are not easily torn, even when the sheets that are impregnated with the drug solution are made of paper and are stacked in a state where they are folded six or more times.

1 is a perspective view of a wet tissue according to an embodiment of the present invention; This is an XY plane image of the height profile (mapping) of the sheet using a microscope. 2B. This is an image of the profile of the height of the irregularities ((measured) cross-sectional curve S) along the line segment S1-S2 in FIG. FIG. 4 is an image of a roughness curve W obtained by processing the (measured) profile curve S of FIG. 3 . FIG. 5 is a diagram showing how to determine the height of the irregularities of the sheet from FIG. 4 that originate from the paper machine. FIG. 2 is a schematic diagram of a location where unevenness derived from a papermaking machine is imparted during the papermaking process of a sheet.

Hereinafter, an embodiment for carrying out the present invention (hereinafter, simply referred to as "the present embodiment") will be described in detail. The following 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.
The MD direction of the wet tissue is the machine direction in which the sheet is conveyed during production, and the CD direction is the cross direction perpendicular to the machine direction.

<Wet tissues>
The wet tissue 1 according to this embodiment is a wet tissue 1 in which a paper sheet 2 containing at least pulp fibers is impregnated with a medicinal solution and laminated in a state where the sheet is folded six or more times.
Since the sheet 2 is made of paper and does not contain synthetic fibers, it is highly biodegradable and can be used as an economical wet tissue 1. The sheet 2 is preferably one-ply or two-ply, and more preferably one-ply.

The folding method of the sheet 2 in six folds is not particularly limited as long as it is a folding method normally used for wet tissues and wet wipes, but an example of this is a folding method in which one side of the short side of the sheet 2 is folded in a mountain fold and the other side is folded in a valley fold (Z fold) to roughly divide the short side into four equal parts, and then the long side is folded in a mountain fold or valley fold (half fold) to roughly divide the long side into two equal parts.

Fig. 1 is a perspective view of a wet tissue 1 according to one embodiment of the present invention. As shown in Fig. 1, the wet tissue 1 is produced by packaging a sheet 2 impregnated with a medicinal solution, folded six or more times, and stacked together in a packaging body 3.
The shape of the packaging body 3 is not particularly limited, but from the viewpoint of compactness, it is preferable that the packaging body 3 is made of a flexible, water-impermeable packaging film as shown in Fig. 1. In addition, it is preferable that the packaging body 3 has an access hole 4.

(Sheet)
The pulp fibers used in the sheet 2 may be general pulp fibers (wood pulp) such as bleached softwood kraft pulp (NBKP) and bleached hardwood kraft pulp (LBKP). Among them, it is preferable to include bleached softwood kraft pulp (NBKP) and bleached hardwood 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.
As the NBKP, for example, fibers made of radiata pine, slash pine, southern pine, lodgepole pine, spruce and Douglas fir are preferred. Note that NUKP can be used instead of NBKP, and LUKP can be used instead of LBKP.

The liquid medicine to be impregnated into the sheet 2 may contain alcohol, a moisturizer, a preservative, an antibacterial agent, a stabilizer, and the like, which are generally used in wet tissues.
At this time, it is preferable that the impregnation ratio of the medicinal solution into the sheet 2 is 2 to 4 times. If the impregnation ratio is less than 2 times, the wettability is insufficient, and the feel of the wet tissue 1 becomes poor, whereas if it exceeds 4 times, the sheet 2 becomes easily torn.

The method of measuring the impregnation ratio is to first measure the area and weight of the wet tissue 1 (sheet 2 impregnated with the chemical solution), then wash the wet tissue 1 with an alcohol solution and completely dry it. After completely drying, the humidity is conditioned in an environment of 23°C and 50% RH, and the weight of the sheet 2 is measured. The weight of the chemical solution impregnated per 1 g of paper is taken as the impregnation ratio.
The impregnation rate is more preferably 2.3 times or more and 3.5 times or less, and further preferably 2.5 times or more and 3.2 times or less.

In order to make it easier to optimize the tensile strength of sheet 2 when wet, which will be described later, it is preferable that sheet 2 does not have water-decomposability. In addition, since the manufacturing process is not limited to equipment such as embossing rolls, there is no decrease in sheet strength due to embossing, and the tensile strength, which will be described later, can be easily optimized, it is preferable that sheet 2 does not have unevenness on either side due to embossing that is not derived from a papermaking machine, which will be described later.

In addition, the sheet 2 has a surface with a pattern of unevenness derived from a paper machine, which is different from the embossing, and the height of the combined height of the convex and concave portions in the unevenness is preferably 100 μm or more and 300 μm or less. If the height of the unevenness is less than 100 μm, the sheets 2 stick to each other and are difficult to take out one by one. If the height of the unevenness exceeds 300 μm, the sheet 2 becomes too bulky and is inferior in compactness when stacked. By having the height of the unevenness within the above numerical range, in the process of pressing the sheets 2 in an adjacent (stacked) state, the number of contact points between the sheets 2 is reduced, making it difficult for the sheets 2 to stick to each other and making it easier to take out one by one.
The combined height of the convex and concave portions is preferably 130 μm to 270 μm, more preferably 150 μm to 250 μm. The unevenness caused by the papermaking machine can be adjusted by a general method such as crepe ratio or wet crepe.

The height of the unevenness of sheet 2 caused by the papermaking machine is measured using a microscope. As the microscope, a product named "One-Shot 3D Measuring Macroscope VR-3100" manufactured by KEYENCE Corporation can be used. As the observation, measurement, and image analysis software for the microscope images, a product named "VR-H1A" can be used. The measurement conditions are a measurement magnification of 12 times and a field of view area of 24 mm x 18 mm. The measurement magnification and field of view area may be changed as appropriate depending on the size of the unevenness desired. Note that while 3D measuring machines and contour shape measuring machines measure points and lines, in the case of one-shot 3D measurement, the entire surface is measured, making it easy to see the overall shape and waviness.

A specific method for measuring the height of unevenness caused by a paper machine will be described with reference to Figures 2 to 5. The measurement is performed on a sheet 2 (wet tissue 1) impregnated with a chemical solution.
Fig. 2(a) is an XY plane image of the height profile (mapping) taken by a microscope. The up-down direction in Fig. 2 is the horizontal direction of the sheet 2, and the left-right direction is the vertical direction of the sheet 2. As shown in Fig. 2(b), by drawing a line segment S1-S2 parallel to the vertical direction at any position on the XY plane image of the height profile (mapping), the unevenness height ((measured) cross-sectional curve S) profile shown in Fig. 3 is obtained. Note that each unevenness extends in the vertical direction, and the line segment S1-S2 crosses these multiple unevennesses, so the unevenness height profile remains almost unchanged no matter where in the vertical direction of the XY plane image the line segment S1-S2 is drawn.

Here, the height profile is a (measured) cross-sectional curve S that represents the actual unevenness of the surface of the sheet 2, but it also contains noise (steep peaks due to fiber clumps, whisker-like fibers, and fiber-free areas on the surface of the sheet 2.) Therefore, when calculating the height of the unevenness, it is necessary to remove such noise peaks.
Therefore, the (measured) profile curve S in Fig. 3 is smoothed with the filter size of the weighted average radio button set to ±12 to obtain the roughness curve W in Fig. 4. Note that smoothing using the filter of the weighted average radio button can be obtained automatically if the above-mentioned analysis software is used.

For the obtained roughness curve W, the difference in the vertical axis between a convex portion and an adjacent concave portion is measured at 10 locations (H1 to H10) as shown in Figure 5, and the average is taken as the height of the unevenness (Rc). In addition, three line segments S1-S2 are set for one height profile image, and three roughness curves W as shown in Figure 4 are obtained. Rc is then calculated for each of these three roughness curves W. Three images of the sample are prepared, and the height of the unevenness calculated by averaging a total of nine pieces of data (Rc) is used.

(Sheet properties)
The basis weight of the sheet 2 in an absolutely dry state is preferably 20 g/ ^m2 or more and 50 g/ ^m2 or less. If the basis weight is less than 20 g/ ^m2 , the sheet 2 will have poor feel, and if it exceeds 50 g/ ^m2 , the sheet 2 will be too bulky and the wet tissue 1 will have poor compactness.
The basis weight of the sheet 2 in an oven-dry state is measured in accordance with JIS P 8124. The basis weight of the sheet 2 in an oven-dry state is more preferably 25 g/ ^m2 or more and 45 g/ ^m2 or less, and even more preferably 30 g/ ^m2 or more and 40 g/ ^m2 or less.

The sheet 2 according to the present embodiment has a tensile strength in a wet state of 2.2 N/25 mm to 3.8 N/25 mm. If the tensile strength is less than 2.2 N/25 mm, the sheet 2 is easily torn, and if it exceeds 3.8 N/25 mm, the feel of the sheet 2 deteriorates.
The tensile strength of the sheet 2 when wet is preferably 2.4 N/25 mm or more and 3.6 N/25 mm or less, and more preferably 2.6 N/25 mm or more and 3.3 N/25 mm or less.

The tensile strength when wet is measured by pulling out one sheet 2 from the stacked wet tissues 1, cutting it to a width of 25 mm, and measuring it ten times with a tensile tester at a gripping width of 100 mm and an extension speed of 300±5 mm/min, and averaging the measured values. The tensile strength in this case means the tensile strength in the CD direction of the sheet 2.
The wet tensile strength of the sheet 2 can be adjusted by a common method such as adding a wet strength agent in the papermaking process. Similarly, the longitudinal and transverse directions (MD and CD) of the sheet 2 can be adjusted by fiber orientation.

Furthermore, it is preferable that the thickness _Tm of the sheet 2 is 160 μm or more and 440 μm or less when a load of 50 gf/ ^cm2 is applied to the sheet 2 using a KES compression tester. If _Tm is less than 160 μm, the feel of the sheet 2 when held in the hand is poor, and if it exceeds 440 μm, the sheet 2 becomes too bulky and is poorly compact when laminated.
The thickness _Tm is more preferably 200 μm or more and 400 μm or less, and further preferably 250 μm or more and 350 μm or less.

Furthermore, when the thickness of the sheet 2 when a load of 0.5 gf/ ^cm2 is applied using a KES compression tester is taken as _T0 , it is preferable that ( _T0 - _Tm )/ _T0 is 0.40 or more. If the value is less than 0.40, the sheet 2 is prone to creases.
It is more preferable that (T ₀ -T _m )/T ₀ is 0.45 or more, and further more preferable that it is 0.50 or more and 0.55 or less.

The above _T0 is preferably 400 μm or more and 800 μm or less. If _T0 is less than 400 μm, the feel of the sheet 2 when held in the hand is poor, and if it exceeds 800 μm, the sheet 2 becomes too bulky and is poorly compact when laminated.
_T0 is more preferably 500 μm or more and 780 μm or less, and further preferably 600 μm or more and 750 μm or less. _Tm and _T0 can be adjusted by the unevenness of the sheet 2 originating from the papermaking machine and the basis weight in an absolute dry state.

In relation to the thickness, the WC (compression work) when the sheet 2 is compressed by a KES compression tester is 0.15 gf cm/ ^cm2 or more and 0.65 gf cm/ ^cm2 or less. If the WC is less than 0.15 gf cm/ ^cm2 , the sheet 2 is likely to be creased, and if it exceeds 0.65 gf cm/ ^cm2 , the sheet 2 becomes too bulky and is inferior in compactness when stacked.
The WC (compression work) is preferably 0.25 gf cm/ ^cm2 or more and 0.55 gf cm/ ^cm2 or less, and more preferably 0.35 gf cm/ ^cm2 or more and 0.50 gf cm/ ^cm2 or less. The WC (compression work) can be adjusted by the unevenness of the sheet 2 caused by the papermaking machine, the basis weight in an absolute dry state, and the tensile strength when wet.

The thickness and WC are measured using a KES-G5 automated compression tester (manufactured by Kato Tech Co., Ltd.).
A sample of wet tissue 1 (sheet 2 impregnated with a drug solution) cut to a size of 140 mm x 200 mm is placed between a ² cm2 pressure plate and a pressure receiving plate. The pressure plate is then lowered at a speed of 0.020 cm/sec, and the pressure change and the thickness of the sample at that time are measured.
_T0 is the thickness (μm) of the sample at a pressure of 0.5 gf/ ^cm2 , and _Tm is the thickness (μm) of the sample at a pressure of 50 gf/ ^cm2 . The values of _T0 and _Tm are calculated as the average value of 10 measurements. WC is the compression work, and is calculated as the average value of 10 measurements in the same manner.

(Wet tissue manufacturing method)
The wet tissue 1 according to this embodiment can be manufactured by the same process as that for ordinary wet tissue products. Specifically, the wet tissue 1 (laminate of sheets 2) can be obtained by the processes of (1) papermaking and creping, (2) cutting, and (3) folding, lamination, and chemical impregnation. The timing of the chemical impregnation may be either before or after lamination, or lamination and impregnation may be performed simultaneously.
In this case, the number of sheets 2 stacked (per one package 3 described later) is not particularly limited as long as it does not result in poor compactness, but it is preferably 10 sheets or more and 50 sheets or less.

In the papermaking process, as described above, it is preferable that a papermaking machine-derived uneven pattern is applied to the sheet 2. By having this uneven pattern, it is easy to optimize the thickness such as _Tm and _T0 and WC of the sheet 2. Here, "originating from the papermaking machine" means that the uneven pattern is applied between the head box of the papermaking machine and the inlet of the Yankee dryer 12 in the papermaking process of the sheet 2.
Specifically, in a part of the papermaking process shown in Fig. 6, unevenness can be imparted in a belt press section 10 arranged between a dewatering roll 11 and a Yankee dryer 12. In the belt press section 10, a wet paper 14 and an uneven belt 13 (the uneven belt 13 loops between the belt press section 10 and the Yankee dryer 12) are pressed together, thereby imparting an uneven pattern to the wet paper 14.

(Processing method, packaging form)
Thereafter, the wet tissue 1 (the laminate of sheets 2 ) is packaged in a package 3 .
The sheet 2 produced by the above-mentioned manufacturing method has a side dimension of preferably 80 mm to 300 mm, more preferably 120 mm to 220 mm. In the above-mentioned papermaking process, the sheet is made in a wide width (e.g., 1000 mm) and then cut into 10 pieces (e.g., 100 mm wide) in a processing machine.

As described above, according to this embodiment, wet tissues can be provided that are made of paper for the sheet that is impregnated with the drug solution, and that have excellent texture and compactness, and are not easily torn, even when stacked in a state where the sheet is folded six or more times.

The present invention will be described in more detail below with reference to examples, but the present invention is not limited to the following examples in any way.

Wet tissues of Examples 1 to 15 and Comparative Examples 1 to 7 were produced under the conditions shown in Tables 1 to 3, and the following evaluations were carried out. Note that each parameter other than the following evaluations was carried out according to the standards or measurement methods described above.
In addition, in each of the examples and comparative examples in Tables 1 to 3, the sheet was folded in six by a Z fold + half fold in all cases, and 30 sheets of the wet tissue stack were packaged in a labeled soft packaging body with an approximately rectangular opening measuring 45 mm x 20 mm.

1. Ease of removal Thirty monitors evaluated the ease of removal of the wet tissues when one wet tissue (sheet) was removed from the package on a four-point scale. The evaluation was performed with ◎ for one sheet being able to be removed reliably, ○ for one sheet being able to be removed at a certain rate, △ for two or more sheets being stuck together and removed in some cases, and × for two or more sheets being stuck together and removed in many cases. The evaluation most frequently selected by the 30 monitors was regarded as the final evaluation.

2. Resistance to tearing of the sheet Thirty monitors took one wet tissue (sheet) out of the package and used it to wipe off dirt, and rated the resistance of the sheet to tearing on a four-point scale. The ratings were as follows: very resistant to tearing, O, somewhat resistant to tearing, △, slightly easy to tear, and ×, with the rating most frequently chosen by the 30 monitors being the final rating.

3. Compactness Thirty monitors evaluated the compactness of the wet tissues (sheets) in a stacked and packaged state on a four-point scale. The evaluation was made based on the most common rating among the 30 monitors, with excellent compactness in use being rated as ⊚, excellent compactness being rated as O, slightly bulky being rated as △, and bulky being rated as ×.

4. Texture Thirty monitors evaluated the texture of the wet tissues (sheets) on a four-point scale. The evaluation was performed with the following criteria: excellent texture = ◎, some texture = ○, slightly poor texture = △, and poor texture = ×, with the most common evaluation selected by the 30 monitors being the final evaluation.

Tables 1 and 2 show the conditions and evaluation results of each example, and Table 3 shows the conditions and evaluation results of each comparative example.

From the above, it was confirmed that wet tissues that have excellent texture and compactness and are not easily torn can be obtained even if the sheet impregnated with the drug solution is made of paper and is folded six or more times and stacked.

Reference Signs List 1 Wet tissue 2 Sheet 3 Package 4 Discharge hole 10 Belt press section 11 Dewatering roll 12 Yankee dryer 13 Concave belt 14 Wet paper

Claims (4)

A wet tissue in which a paper sheet containing at least pulp fiber is impregnated with a chemical solution and folded six or more times and laminated,
The sheet has a compression work capacity (WC) of 0.15 gf cm/cm2 or ^more and 0.65 gf cm/ ^cm2 or less when compressed using a KES compression tester;
The wet tissue is characterized in that the sheet has a tensile strength of 2.2 N/25 mm or more and 3.8 N/25 mm or less when wet. The wet tissue according to claim 1, wherein, when a thickness of the sheet when a load of 50 gf/ ^cm2 is applied to the sheet using a KES compression tester is T _m and a thickness of the sheet when a load of 0.5 gf/ ^cm2 is applied to the sheet using a KES compression tester is T ₀ , (T ₀ -T _m )/T ₀ is 0.40 or more. The wet tissue according to claim 1, wherein the thickness _Tm of the sheet when a load of 50 gf/ ^cm2 is applied to the sheet using a KES compression tester is 160 μm or more and 440 μm or less. The sheet has a paper machine-derived uneven pattern on its surface,
2. The wet tissue according to claim 1, wherein the height of the concaves and convexities combined is 100 μm or more and 300 μm or less.