JP7630287B2 - Cleaning wipes - Google Patents

Description

The present invention relates to a wet cleaning sheet.

It has been known that embossing the cleaning surface of a wet cleaning sheet with convex parts improves the ease of wiping off dirt, operability, and visibility of dirt on the sheet (see, for example, Patent Document 1).

JP 2018-064723 A

However, in the case of wet cleaning sheets as shown in Patent Document 1, the projections on the sheet are aligned in a straight line (for example, in the direction of the long axis), which can result in areas on the surface to be cleaned that have not been wiped by the projections (so-called "wiping streaks"). When a user sees the wiping streaks, they may decide that the sheet has run out of chemical solution and dried out, even though there is still chemical solution remaining in the sheet, and discard the sheet, which can result in the user using many sheets unnecessarily.

The object of the present invention is to provide a cleaning wet sheet that can reduce the occurrence of wiping streaks when attached to a cleaning tool having a head portion and used for wiping.

The invention described in claim 1 is a wet cleaning sheet comprising a base paper sheet impregnated with a chemical solution and attached to a cleaning tool having a head portion,
The first surface of the cleaning wet sheet is provided with an embossing block having a plurality of convex embossments,
a plurality of the embossing blocks are arranged continuously from a first side to a second side opposite to the first side to form an embossing block row;
a non-embossed portion where the embossing is not arranged between adjacent ones of the embossing blocks;
the embossed block rows are arranged continuously from a third side perpendicular to the first side to a fourth side opposite to the third side,
The non-embossed portion is provided so as to occupy 25% or more and 50% or less of the area of the cleaning wet sheet,
the protruding embossments are arranged so that at least one is present on a straight line extending perpendicularly from an arbitrary point on the third side to the fourth side ,
The base paper sheet comprises a hydrophobic fiber layer forming a surface of the sheet;
a hydrophilic fiber layer sandwiched between the hydrophobic fiber layers,
The boundary region between the hydrophobic fiber layer and the hydrophilic fiber layer is characterized in that the fibers of both layers are entangled .

The invention described in claim 2 is the cleaning wet sheet described in claim 1,
The second surface of the wet cleaning sheet is provided with a concave embossment, which is a convex embossment,
The embossing block is composed of a combination of a plurality of the convex embossments and the concave embossments,
The recessed embossments are characterized in that at least one of them is disposed on a line extending from an arbitrary point on the third side to the fourth side.

The invention described in claim 3 is the cleaning wet sheet according to claim 1 or 2 ,
an angle between a major axis direction of the embossment and a first direction perpendicular to the first side is 30° or more and 60° or less;
The embossing block is characterized in that it is rhombus-shaped.

The invention described in claim 4 is the cleaning wet sheet according to any one of claims 1 to 3 ,
The embossment is elliptical in shape and has a constricted portion at approximately the center in the major axis direction.

The present invention provides a cleaning wet sheet that can reduce the occurrence of wiping streaks when attached to a cleaning tool having a head portion and used for wiping.

FIG. 1 is a perspective view of a cleaning tool to which a wet cleaning sheet according to an embodiment of the present invention is attached. FIG. 2 is a plan view showing the cleaning wet sheet of the present embodiment. FIG. 3 is a cross-sectional view taken along line III-III of FIG. 2 . FIG. 11 is a plan view showing a modified example of a wet cleaning sheet. FIG. 2 is a plan view showing an embossing pattern according to an embodiment of the present invention. FIG. 2 is a plan view showing an embossing pattern according to an embodiment of the present invention. FIG. 11 is a plan view showing an embossed pattern according to a comparative example. FIG. 11 is a plan view showing an embossed pattern according to a comparative example.

Hereinafter, a wet cleaning sheet 100 according to an embodiment of the present invention will be described with reference to the drawings. However, the scope of the invention is not limited to the illustrated examples, and is determined solely based on the description of the claims.
In the following description, the X, Y, and Z directions are defined as shown in Fig. 1. In addition, in this specification, "to" is used to mean that the numerical values before and after it are included as the lower limit and upper limit.

[Configuration of the embodiment]
FIG. 1 is a diagram showing a state in which a wet cleaning sheet 100 according to the present embodiment is in use.
As shown in FIG. 1, the cleaning wet sheet 100 is a sheet in which a chemical solution is impregnated into a base paper sheet made of multiple fiber aggregate substrates plyed (laminated), and which is used for cleaning floors by being replaceably attached to a cleaning tool 200 having, for example, a rectangular, flat head portion 201 and a handle portion 202 attached to the upper surface of the head portion 201.

The cleaning wet sheet 100 as shown in FIG. 2 covers the bottom surface of the head portion 201 of the cleaning tool 200 to form a cleaning surface, and is folded at a fold line S along the longitudinal edge portion 201a of the head portion 201 of the cleaning tool 200 to be engaged with the upper surface of the head portion 201 and attached thereto.
The long edges 201a refer to edges along the long direction of the head portion 201. In other words, they refer to the two longer edges of the four edges of the rectangular head portion 201.

Fiber aggregate substrates are nonwoven fabrics produced by bonding specific fibers together using well-known techniques such as spunlace, air-through, airlaid, point bond, spunbond, and needle punch.

FIG. 3 is a cross-sectional view taken along line III-III in FIG.
3, the cleaning wet sheet 100 has, for example, a three-layer structure, with the surface layers on both sides being hydrophobic fiber layers 11, 11 mainly made of hydrophobic fibers, and the middle layer being a hydrophilic fiber layer 12 mainly made of hydrophilic fibers. In addition, the boundary region between the fibers of the hydrophobic fiber layers 11, 11 and the fibers of the hydrophilic fiber layer 12 is configured so that the fibers are entangled with each other.

Therefore, the chemical solution impregnated in the hydrophilic fiber layer 12 is less likely to be released onto the surface to be cleaned adjacent to the hydrophobic fiber layer 11, and the chemical solution can be selectively released onto the floor surface, thereby suppressing the release of chemical solution that is not effective for cleaning.
In addition, by configuring the hydrophobic fibers and the hydrophilic fibers to be intertwined with each other, the air held in the intertwined portions can further increase the retention of the drug solution.

(hydrophilic fiber)
As the hydrophilic fiber, natural fibers such as cotton, pulp, and hemp, and regenerated fibers such as rayon and cupra can be used, but from the viewpoint of maintaining water retention, it is preferable to use pulp, rayon, polypropylene spunbond fiber (PPSB), etc.

(Hydrophobic fiber)
Examples of hydrophobic fibers include polyolefin fibers such as polyethylene (PE), polypropylene (PP), and polyvinyl alcohol, polyester fibers such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT), and acrylic fibers, which can be used alone or in combination of two or more. Examples of composite fibers of two or more types include a core-sheath type having a sheath of a resin with a relatively low melting point (low melting point resin) and a core of a resin with a relatively high melting point (high melting point resin), and a side-back type in which a low melting point resin and a high melting point resin are arranged in parallel in a predetermined direction.

(Eyewear)
In the case of the cleaning wet sheet 100 of the present invention, the basis weight is preferably 30 g/m ² to 120 g/m ² , particularly preferably about 60 g/m ² to 100 g/m ^2. If the basis weight is less than 30 g/m ² , the dirt retention ability is poor, and the cleaning wet sheet 100 is likely to wrinkle and become unstable during cleaning. If the basis weight exceeds 120 g/m ² , the flexibility is poor, making it difficult to attach the cleaning wet sheet 100 to the cleaning tool 200.

(CNF)
Furthermore, cellulose nanofiber (CNF) can be added to the cleaning wet sheet 100.
CNF refers to fine cellulose fibers obtained by defibrating pulp fibers, and generally refers to cellulose fibers containing cellulose fine fibers with a fiber width of nano size (1 nm to 1000 nm), but fibers with an average fiber width of 100 nm or less are preferable. The average fiber width can be calculated, for example, by using a certain number of number averages, medians, mode diameters (mode values), etc.

The CNF may be uniformly impregnated in the thickness direction of the base paper sheet, but it is preferable that the CNF content gradually increases from the center of the thickness direction of the base paper sheet toward the front and back surfaces. This makes the cleaning wet sheet 100 less likely to tear even if the cleaning surface is rubbed hard.

(Pulp fibers that can be used for CNF)
Pulp fibers that can be used to produce CNF include chemical pulps such as hardwood pulp (LBKP) and softwood pulp (NBKP); mechanical pulps such as bleached thermomechanical pulp (BTMP), stone ground pulp (SGP), pressed stone ground pulp (PGW), refiner ground pulp (RGP), chemi-ground pulp (CGP), thermo-ground pulp (TGP), ground pulp (GP), thermomechanical pulp (TMP), chemi-thermomechanical pulp (CTMP), and refiner mechanical pulp (RMP); waste paper pulp produced from brown paper, kraft envelope paper, magazine paper, newspaper paper, flyer paper, office paper, cardboard paper, white waste paper, Kent waste paper, imitation waste paper, land certificate waste paper, and recycled paper; and deinked pulp (DIP) produced by deinking waste paper pulp. These may be used alone or in combination as long as the effects of the present invention are not impaired.

(CNF defibration method)
Examples of defibration methods used in the production of CNF include mechanical methods such as a high-pressure homogenizer method, a microfluidizer method, a grinder grinding method, a bead mill freeze-pulverizing method, and an ultrasonic defibration method, but are not limited to these methods.
In addition, CNF that has only been mechanically treated (not modified) using the above-mentioned defibration method, i.e., CNF that has not been modified with functional groups, has higher thermal stability than CNF modified with functional groups such as phosphate groups and carboxymethyl groups, and can therefore be used for a wider range of applications; however, CNF modified with functional groups such as phosphate groups and carboxymethyl groups can also be used in the present invention.
In addition, for example, pulp fibers may be mechanically defibrated and then chemically treated, such as carboxymethylated, or may be enzymatically treated. Examples of CNF that have been chemically treated include individualized CNF (single nanocellulose) with a diameter of 3 nm to 4 nm, such as TEMPO-oxidized CNF, phosphate-esterified CNF, and phosphite-esterified CNF.
In addition, CNF that has been subjected to only chemical or enzymatic treatment, or CNF that has been subjected to chemical or enzymatic treatment and then mechanical defibration treatment may be used.

[Chemical solution]
The cleaning wet sheet 100 of this embodiment is impregnated with a predetermined chemical solution containing an auxiliary such as glycol ethers, an aqueous detergent, a preservative, a disinfectant, a lower alcohol, an organic solvent, etc. The chemical solution is impregnated in an amount of 100% by mass to 500% by mass, preferably 150% by mass to 300% by mass, based on the mass of the base paper sheet which is the substrate of the cleaning wet sheet 100.
The chemical solution is impregnated into the dried base paper sheet, and the chemical solution impregnated into the hydrophilic fiber layer 12 is released from the hydrophobic fiber layer 11 on the front or back side when the cleaning wet sheet 100 is used.

[Emboss]
As shown in Figs. 1 and 2, the wet cleaning sheet 100 has embossments 20 formed by compressing the sheet in the Z direction.
The embossment 20 is formed in a so-called gourd shape, which is an elongated ellipse that is short in one direction and narrow in width in a plan view, with a constricted portion at approximately the center in the long axis direction, as shown in Fig. 2. The shape of the embossment 20 is not limited to this, and may be various shapes such as a polygon, or a combination of various shapes, but from the viewpoint of improving the ability to scrape off dirt, such a gourd shape is preferable.

The embossments 20 can be formed by thermal embossing under conditions of, for example, a temperature of 80° C. to 200° C. and an embossing pressure of 0.2 MPa to 1.0 MPa. When the embossments 20 are formed by thermal embossing, the convex embossing roll may be one having at least an outer circumferential surface made of carbon steel, stainless steel, polypropylene, or a hardened resin such as ABS (Acrylonitrile Butadiene Styrene) resin, among which, from the viewpoints of durability and heat resistance, it is preferable to use one made of stainless steel.
Furthermore, when embossing is performed by thermal embossing, it is preferable to perform this before the step of impregnating the wet cleaning sheet 100 with a chemical solution, in order to easily impart the uneven shape.

(Convex embossing, concave embossing)
The embossment 20 is formed with a convex embossment 21 that is convex on the upper side in the Z direction (the first surface side of the wet cleaning sheet 100) and a concave embossment 22 that is convex on the lower side (the second surface side of the wet cleaning sheet 100) (i.e., concave on the upper side in the Z direction). In each drawing, the convex embossment 21 is shown by a solid line and the concave embossment 22 is shown by a dashed line.

The convex embossment 21 is formed to have a size of 5 mm to 10 mm, preferably 6 mm to 8 mm in the long axis direction, 2 mm to 5 mm, preferably 3 mm to 4 mm in the short axis direction perpendicular to the long axis direction, and 0.5 mm to 2 mm, preferably 0.7 mm to 1.5 mm in the Z direction (height from the middle part (described later)). The concave embossment 22 is formed upside down and in approximately the same shape as the convex embossment 21 in cross-sectional view, and is formed to have a shape that is convex downward in the Z direction.

(Middle part)
An intermediate portion is formed between each of the embossments 20 formed on the cleaning wet sheet 100. Since the intermediate portion is a portion where no embossment 20 is formed, the intermediate portion is located lower than the convex embossment 21 and higher than the concave embossment 22 in the Z direction.

[Emboss pattern]
In the wet cleaning sheet 100 according to the present embodiment, for example, as shown in FIG. 2, a diamond-shaped first embossed block 30 is formed by a combination of a convex embossment 21 and a concave embossment 22 such that an angle between a first direction (X direction in FIG. 2) perpendicular to a first side a and the long axis direction is 30° to 60°. The first embossed block 30 is arranged in a row 31 from the first side a to the second side b, and the row 31 is arranged in a row from the third side c to the fourth side d. In adjacent first embossing block rows 31 and second embossing block rows 31, a first embossing block 30 in the first embossing block row 31 overlaps with an adjacent second embossing block 30 in the second embossing block row 31 in a second direction (Y direction in Figure 2) perpendicular to the first direction, and the rows are arranged so that at least one convex embossing 21 and one concave embossing 22 exist on a straight line extending from any point on the third side c perpendicular to the fourth side d.

(Non-embossed part)
As shown in FIG. 2, between adjacent embossed blocks 30, the wet cleaning sheet 100 is not compressed in the Z direction, and a non-embossed portion 40 having nap is provided.

The non-embossed portion 40 can be formed by designing the convex embossing roll that forms the embossment 20 so as to exclude the shape of the non-embossed portion 40, or by compressing it lightly compared to the compressed portion of the embossment 20 so that the nap remains.
By providing such non-embossed portions 40 covering 25% to 50% of the area of the wet cleaning sheet 100, the occurrence of wiping streaks can be reduced, resulting in a wet cleaning sheet 100 with excellent wiping ability.

When the wet cleaning sheet 100 is attached to the cleaning tool 200 and used for wiping, it is moved approximately perpendicular to the X or Y direction. However, as shown in FIG. 2, if the non-embossed portion 40 is formed to be in a straight line, wiping streaks may easily occur depending on the angle at which the wet cleaning sheet 100 is moved. Therefore, it is more desirable to position the embossed block 30 so that the non-embossed portion 40 is not in a straight line.

[Effects of the Invention]
Normally, when wiping is performed using a cleaning tool 200 having a head unit 201, it is moved in a first direction or a second direction, but when a cleaning wet sheet 100 is attached which has the above-mentioned embossing pattern and is arranged so that at least one convex embossment 21 is present on a straight line extending perpendicularly from any point on the third side c to the fourth side d, when wiping is performed at least in the second direction (the Y direction in Figure 2), the convex embossments 21 will have an overlapping margin, thereby reducing the occurrence of wiping streaks.

In addition, by not providing embossments 20 on the entire surface of the cleaning wet sheet 100, but providing non-embossed sections 40 between each embossed block 30, covering 25% to 50% of the area of the cleaning wet sheet 100, when wiping with the cleaning wet sheet 100, the convex embossments 21 that protrude beyond the non-embossed sections 40 are subjected to greater pressure, improving the release of chemicals and further reducing the occurrence of wiping streaks.
Furthermore, by receiving a larger pressure on the convex embossments 21, the scraping ability of the convex embossments 21 is improved, and dirt is more likely to accumulate in the non-embossed portions 40, thereby improving the dirt collection ability. Even if the scraping ability of the convex embossments 21 and the dirt collection ability of the cleaning wet sheet 100 are improved, the convex embossments 21 make it more difficult for the non-embossed portions 40 to come into contact with the surface to be cleaned, thereby suppressing an increase in wiping resistance.

The cleaning wet sheet 100 has a three-layer structure in which the hydrophilic fiber layer 12 is sandwiched between the hydrophobic fiber layers 11, 11, so that the chemical solution held in the hydrophilic fiber layer 12 is selectively released onto the surface to be cleaned. The air held in the intertwined portion of the hydrophobic fiber layer 11 and the hydrophilic fiber layer 12 can further enhance the retention of the chemical solution.

In addition, since the embossed block 30 is diamond-shaped and made of embossments 20 that form an angle of 30° to 60° between the first direction and the long axis direction, when a plurality of embossed block rows 31, each of which is arranged continuously from the first side a to the second side b, are arranged continuously from the third side c to the fourth side d, the embossed blocks 30 are inevitably arranged so as to be misaligned with respect to the first direction of the wet cleaning sheet 100. In addition, this allows more leeway in the angle at which the wet cleaning sheet 100 can be moved when the user is wiping.

In addition, the embossment 20 is elliptical in shape and has a constricted portion approximately in the center in the long axis direction, which improves dirt scraping performance.

[Modification]
Of course, other specific details of the structure can be modified as appropriate.

For example, in the above description, the wet cleaning sheet 100 is exemplified as having the embossed block 30 formed of a combination of the convex embossments 21 and the concave embossments 22 , but the embossed block 30 only needs to have at least the convex embossments 21 .
However, providing the concave embossments 22 is preferable because it allows the cleaning wet sheet 100 to be turned over for use, thereby enabling a larger cleaning area to be achieved.

In addition, in Figures 1 and 2, a diamond-shaped embossed block 30 is shown as an example, which is made up of embossments 20 in which the angle between the first direction and the long axis direction is 30° to 60°, but the shape of the embossed block 30 is not limited to this, and it may be, for example, an embossed block 30 made up of embossments 20 in which the angle between the first direction and the long axis direction is 0° or 90°.

In addition, in Figures 1 and 2, the convex embossings 21 and the concave embossings 22 in each embossing block 30 are illustrated as having the same angle between the long axis direction and the first direction, but this is not limited to this, and as shown in Figure 4, the long axis direction of the convex embossings 21 and the concave embossings 22 in the first embossing block 30 may be arranged so that it is different from the long axis direction of the convex embossings 21 and the concave embossings 22 in the second embossing block 30 adjacent to the first embossing block 30.
Moreover, the convex embossments 21 and the concave embossments 22 in the first embossing block 30 may be arranged so that their angles are different from each other.

Moreover, the chemical solution impregnated in the wet cleaning sheet 100 can be changed depending on the application.
Further, the cleaning wet sheet 100 has been described as having a three-layer structure, but is not limited to this.
In addition, in each figure, the first side a and the second side b are the short sides of the cleaning wet sheet 100, and the third side c and the fourth side d are the long sides of the cleaning wet sheet 100, but this is not limited to this.

In addition, in each figure, the convex embossing 21 and the concave embossing 22 are both substantially the same gourd shape in plan view, but the convex embossing 21 and the concave embossing 22 may have different shapes.

However, in any of the above embossing patterns, it is preferable that the convex embossments 21 and the concave embossments 22 are arranged so as to be approximately symmetrical on the first and second sides of the wet cleaning sheet 100. In this way, the first and second sides of the wet cleaning sheet 100 have the same level of cleaning function, and the cleaning area per sheet can be increased.

Next, the results of evaluating the preferred configurations of the examples of the present invention and the comparative examples will be described. The present invention will be specifically described below using examples, but the present invention is not limited to these.

[Sample Creation]
First, two hydrophobic fiber layers each having a basis weight of 40 g/ ^m2 to 50 g/ ^m2 and consisting of 80% PET and 20% PP/PE binder, and one hydrophilic fiber layer having a basis weight of 40 g/ ^m2 to 50 g/ ^m2 and consisting of 70% pulp and 30% PPSB were prepared, and the hydrophilic fiber layer was entangled by a water flow entanglement method so that both sides of the hydrophilic fiber layer were sandwiched between the hydrophobic fiber layers, and then cut to a size of 300 mm x 200 mm to prepare a base paper sheet.
Next, the base paper sheet was subjected to thermal embossing at a temperature of 95° C. and an embossing pressure of 0.4 MPa so as to obtain the embossing patterns of Examples 1-3 and Comparative Examples 1-3 described below, to prepare test sheets.

(Example 1: Non-embossed portion 25%)
As shown in FIG. 2 , a plurality of diamond-shaped first embossed blocks 30 each consisting of a combination of a gourd-shaped convex embossment 21 and a concave embossment 22 are arranged in succession from a first side a to a second side b opposite to the first side a. The first embossed block rows 31 are arranged in succession from a third side c to a fourth side d. The first embossed block rows 31 are each formed by arranging a plurality of diamond-shaped first embossed blocks 30 in succession from a first side a to a second side b opposite to the first side a. In this case, in adjacent first embossed block rows 31 and second embossed block rows 31, the first embossed block 30 in the first embossed block row 31 overlaps with the adjacent second embossed block 30 in the second embossed block row 31 in the first direction, and the embossments 20 are arranged so that at least one convex embossment 21 exists on a line extending perpendicularly from an arbitrary point on the third side c to the fourth side d, and non-embossed portions 40 are provided between each embossed block 30 so as to cover 25.0% of the area of the base paper sheet.

(Example 2: Non-embossed portion 37.5%)
As shown in FIG. 5A, the non-embossed portion 40 was provided so as to cover 37.5% of the area of the base paper sheet.
The other conditions are the same as those in the first embodiment.

(Example 3: Non-embossed portion 50%)
As shown in FIG. 5B, the non-embossed portion 40 was provided so as to cover 50.0% of the area of the base paper sheet.
The other conditions are the same as those in the first embodiment.

(Comparative Example 1: 0% non-embossed portion, arranged in series)
As shown in FIG. 5C , gourd-shaped convex embossments and concave embossments whose major axes are oriented parallel to the first direction were arranged alternately over the entire surface of the base paper sheet to create a test sheet having no non-embossed portion 40.
(Comparative Example 2: 0% non-embossed area, zigzag shape)
The gourd-shaped embossing has a plurality of first convex embossments and second convex embossments whose orientations in the long axis direction are different from each other, and the first convex embossments adjacent to each other in the short axis direction are arranged so that both first convex embossments partially overlap in the short axis direction and are shifted in the long axis direction, and the second convex embossments adjacent to each other in the short axis direction are arranged so that both second convex embossments partially overlap in the short axis direction and are shifted in the long axis direction.
Such a plurality of first convex embossments and second convex embossments were adjacent to each other so that their major axis directions were at approximately right angles to each other, and were continuously arranged from a first side a of the base paper sheet toward a second side b opposite to the first side a.
In addition, concave embossments were arranged in the same embossing pattern as the convex embossments so as to alternate with the convex embossments, and a test sheet having no non-embossed portion 40 as shown in FIG. 5D was prepared.
(Comparative Example 3: Non-embossed portion 100%)
A test sheet was prepared without embossing, having only a non-embossed portion 40 .

The test sheets of Examples 1-3 and Comparative Examples 1-3 were impregnated with 300% by mass of each of a chemical solution containing an aqueous detergent, a preservative, a disinfectant, and alcohol based on the dry weight to create wet sheets of Examples 1-3 and Comparative Examples 1-3. These were then attached to a cleaning tool with a flat head portion measuring 250 mm x 100 mm to create wipers with wet sheets of Examples 1-3 and Comparative Examples 1-3.

The following tests 1-3 were conducted using the wet sheet wipers of Examples 1-3 and Comparative Examples 1-3.

[Test 1. Wipe streak test]
(1) Place a wet sheet wiper with weights added so that the total weight is 400 g on the right edge of the blackboard with the head facing directly.
(2) Push the wiper with weight and wet sheet from the right end to the left end of the blackboard, moving it 300 mm.
(3) The resulting wiping streaks were visually evaluated as follows: ◯: almost no wiping streaks on the cleaning surface (wet area was about 90% to 100% of the entire cleaning surface); △: slight wiping streaks (wet area was about 80% to 90% of the entire cleaning surface); and ×: many wiping streaks (wet area was 80% or less of the entire cleaning surface).

[Test 2. Wiping performance test]
(1) 15 ml of artificial soil made from a mixture of beef tallow, olive oil, chloroform and fluorescent paint in a ratio of 12.5:12.5:74.4:0.6 (mass ratio) was dropped onto a 480 mm x 320 mm stainless steel plate and spread out, followed by drying for 5 minutes in a hot air dryer (temperature 60°C), and then measuring the weight of the stainless steel plate.
(2) Place a wet sheet wiper with weights added so that the total weight is 500 g on the right end of the stainless steel plate with the head facing directly.
(3) Push and move the weight and the wet sheet wiper from the right end of the stainless steel plate to the left end, and dry only the stainless steel plate again in a hot air dryer (temperature 60°C) for 5 minutes and measure the weight.
(4) The wiping amount of each cleaning wet sheet is calculated from the difference between the weight of the stainless steel plate before the test measured in (1) and the weight of the stainless steel plate after the test measured in (3).
(5) The steps (1) to (4) are repeated twice, and the average amount of wiped off is calculated.

[Test 3. Wipe resistance test]
(1) Place a wet sheet wiper with weights added so that the total weight is 500 g on the composite flooring with the head facing directly.
(2) Drill a hole in the head connection part of the wiper body, and attach a push-pull gauge (DS2-200N manufactured by Imada Co., Ltd.) to the hole.
(3) Measure the maximum resistance value when a wet sheet wiper equipped with a push-pull gauge is pulled 50 cm.
(4) The operation (3) is repeated five times, and the average wiping resistance is calculated.

The results of tests 1-3 are shown in Table I.

[evaluation]
Comparing the results of Test 1, it can be seen that the occurrence of wiping streaks is reduced in Example 1-3 in which the non-embossed portion 40 is provided, compared to Comparative Example 1 and Comparative Example 2 in which the non-embossed portion 40 is not provided. This is thought to be because the pressure applied to the convex embossment 21 is increased by the amount of the non-embossed portion 40 provided, and the release of the chemical solution is improved.
On the other hand, when comparing Examples 1 to 3 and Comparative Example 3, the occurrence of wiping streaks increased, albeit slightly, as the ratio of the non-embossed portion 40 was increased. This is thought to be because as the ratio of the non-embossed portion 40 is increased, the number of protruding embossments 21 decreases accordingly, reducing the contact area with the blackboard and decreasing the release of the chemical solution.

Furthermore, when comparing the results of Test 2, it can be seen that Example 1-3, which has a non-embossed portion 40, has a greater wiping amount than Comparative Example 1 and Comparative Example 2, which do not have a non-embossed portion 40, and therefore has improved wiping performance.
On the other hand, when comparing Examples 1 to 3, it is found that Example 1, which has 25% non-embossed portion 40, is able to wipe off the most dirt, and the amount of dirt wiped off decreases as the non-embossed portion 40 increases. This is thought to be because, as described above, as the ratio of non-embossed portion 40 increases, the number of convex embossments 21 decreases accordingly, decreasing the release of chemicals and the ability to scrape off dirt.

Furthermore, when comparing the results of Test 3, only Comparative Example 3, which did not have an embossing 20 on the entire surface, had a stronger wiping resistance, but no significant difference in wiping resistance was observed between Comparative Examples 1 and 2, which did not have a non-embossed portion 40, and Examples 1-3, which had a non-embossed portion 40.
This is thought to be because the non-embossed portion 40 is less likely to come into contact with the surface to be cleaned, and therefore the wiping resistance of the entire wet cleaning sheet 100 does not change significantly.

100 Wet cleaning sheet 11 Hydrophobic fiber layer 12 Hydrophilic fiber layer 20 Embossment 21 Convex embossment 22 Concave embossment 30 Embossed block 31 Embossed block row 40 Non-embossed portion 200 Cleaning tool 201 Head portion a First side b Second side c Third side d Fourth side

Claims (4)

A wet cleaning sheet comprising a base paper sheet impregnated with a chemical solution and attached to a cleaning tool having a head portion,
The first surface of the cleaning wet sheet is provided with an embossing block having a plurality of convex embossments,
a plurality of the embossing blocks are arranged continuously from a first side to a second side opposite to the first side to form an embossing block row;
a non-embossed portion where the embossing is not arranged between adjacent ones of the embossing blocks;
the embossed block rows are arranged continuously from a third side perpendicular to the first side to a fourth side opposite to the third side,
The non-embossed portion is provided so as to occupy 25% or more and 50% or less of the area of the cleaning wet sheet,
the protruding embossments are arranged so that at least one is present on a straight line extending perpendicularly from an arbitrary point on the third side to the fourth side ,
The base paper sheet comprises a hydrophobic fiber layer forming a surface of the sheet;
a hydrophilic fiber layer sandwiched between the hydrophobic fiber layers,
The cleaning wet sheet is characterized in that the hydrophobic fiber layer and the hydrophilic fiber layer have intertwined fibers in a boundary region therebetween . The second surface of the wet cleaning sheet is provided with a concave embossment, which is a convex embossment,
The embossing block is composed of a combination of a plurality of the convex embossments and the concave embossments,
The wet cleaning sheet according to claim 1, wherein at least one of the recessed embossments is disposed on a line extending from an arbitrary point on the third side to the fourth side. an angle between a major axis direction of the embossment and a first direction perpendicular to the first side is 30° or more and 60° or less;
3. The wet cleaning sheet according to claim 1, wherein the embossed block is rhombus-shaped. 4. The wet cleaning sheet according to claim 1, wherein the embossment is elliptical in shape and has a constricted portion at approximately the center in the major axis direction.

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