TWI896661B - Cleaning sheets - Google Patents

Abstract

The present invention provides a cleaning sheet having excellent dirt removal performance and water release properties, and can continuously exhibit its excellent dirt removal performance. The cleaning sheet (1) of the present invention comprises: a water-retaining layer (3) and a surface layer (2). The surface layer is laminated on at least one side of the water-retaining layer (3) to form a wiping surface. The surface layer (2) has, at least on the wiping surface: a plurality of openings (50) penetrating the surface layer (2) in the thickness direction, and non-openings (53) other than the openings (50). The water-retaining layer (3) and the surface layer (2) are partially bonded.

Description

Cleaning sheets

The present invention relates to a disposable cleaning sheet for wiping dust and garbage from cleaning objects such as floors, furniture, and home appliances.

As cleaning tools for cleaning indoor floors, furniture, home appliances, etc., there are known disposable cleaning sheets that can clean the objects in a wet state (wet state).

In addition, various cleaning sheets have been proposed in recent years. For example, Patent Document 1 discloses a cleaning tool comprising a cleaning sheet mounting member and a cleaning sheet, wherein the central portion of the cleaning sheet comprises: a hydrophobic first sheet, a hydrophobic second sheet, a hydrophilic third sheet, and a fourth sheet.

Patent document 2 discloses a wet cleaning sheet comprising a fiber aggregate formed by interweaving a fiber web with water flow, wherein a mesh sheet is disposed within the fiber aggregate, and at least one side of the fiber aggregate has: a plurality of protrusions formed by the interweaving of the constituent fibers, and concave portions shaped to surround the protrusions. Furthermore, the static friction resistance value of the aforementioned side of the fiber aggregate is 900 to 2500 cN.

Patent Document 3 discloses a water-disintegrable wiping sheet having a multi-layer structure comprising: a water-disintegrable front sheet and a back sheet formed of water-dispersible fibers; and a water-disintegrable middle sheet disposed between these sheets. The front sheet and the back sheet are provided with a plurality of openings penetrating the layer. These openings are blocked by the middle sheet at the boundary with the middle sheet, resulting in both sides of the sheet serving as wiping surfaces. [Prior Art Document] [Patent Document]

[Patent Document 1] Japanese Patent No. 5777325 [Patent Document 2] Japanese Patent Application Publication No. 2011-224385 [Patent Document 3] Japanese Patent Application Publication No. 2001-275875

[Identify the problem you want to solve]

The cleaning sheet disclosed in Patent Document 1 has a three-layer structure, with the first through fourth sheets serving as a water-retaining layer (inner layer) and a surface layer (outer layer). While the lack of a central joint allows for excellent water-releasing properties, the flat surface of the nonwoven fabric forming the surface layer poses a concern for insufficient performance in removing dirt such as dust and debris (hereinafter referred to as "dirt removal performance"). On the other hand, the cleaning wet sheet disclosed in Patent Document 2 is composed of a single-layer fiber aggregate (nonwoven fabric). Furthermore, by disposing a mesh sheet within it, the nonwoven fabric has increased strength, enabling it to exhibit a certain degree of dirt removal performance. However, due to the single-layer structure of the nonwoven fabric, there is still room for improvement in the release of water from the cleaning solution, etc. (hereinafter referred to as "water release") from the nonwoven fabric. Furthermore, the water-disintegrable wiping sheet disclosed in Patent Document 3 has a structure in which a plurality of openings are provided on the surface sheet, and the boundaries between the openings and the intermediate sheet are blocked by the intermediate sheet. This structure facilitates the retention of dirt such as garbage and dust within the openings, thereby exhibiting a certain strength and garbage-collecting capacity (i.e., dirt-removing performance). However, once dirt is retained within the openings, it remains there, resulting in the inability to remove the dirt from the cleaning object, i.e., the problem of not being able to continuously exert the dirt-removing performance.

The present invention aims to provide a cleaning sheet that exhibits excellent dirt removal performance and water release properties, while also being able to sustainably demonstrate its excellent dirt removal performance. [Technical Solution]

One embodiment of the present invention (Aspect 1) is a cleaning sheet comprising: a water-retaining layer; and a surface layer, the surface layer being laminated on at least one side of the water-retaining layer to form a wiping surface. The cleaning sheet is characterized in that: The surface layer, at least on the wiping surface, has a plurality of openings extending through the surface layer in the thickness direction, and non-opening portions other than the openings; The water-retaining layer and the surface layer are partially bonded.

The cleaning sheet of aspect 1 has a plurality of openings on at least the wiping surface of its surface layer. The stepped edges of the openings scrape away dirt, dust, and other contaminants when wiping the object, thereby exhibiting excellent dirt removal performance. Furthermore, the cleaning sheet of aspect 1 has non-openings, such as those between adjacent openings, on at least the wiping surface of its surface layer. This allows the cleaning solution retained in the surface layer and water-retaining layer to be appropriately released onto the object, thereby exhibiting excellent moisture release. Furthermore, the cleaning sheet of Embodiment 1 partially joins the water-retention layer and the surface layer, allowing the surface layer to easily move in a staggered manner relative to the water-retention layer. Therefore, even if scraped dirt remains within the opening, the staggered movement of the water-retention layer and the surface layer during wiping allows the dirt within the opening to be captured within the water-retention layer or at the boundary between the water-retention layer and the surface layer, while the dirt is formed on the surface of the water-retention layer newly exposed at the bottom of the opening. In this way, the cleaning sheet of Embodiment 1 can continuously demonstrate the excellent dirt removal performance described above.

In another aspect (Aspect 2) of the present invention, in the cleaning sheet of Aspect 1, the cleaning sheet has a first direction and a second direction that are orthogonal to each other, and the water-retaining layer and the surface layer are joined at both end regions in the second direction.

In the cleaning sheet of embodiment 2, the water-retention layer and the surface layer are joined at both end regions in the second direction (e.g., the widthwise direction). While maintaining the structure of the cleaning sheet, the surface layer is formed in the central region in the second direction. This allows the surface layer to easily shift relative to the water-retention layer in the second direction (ideally, the direction corresponding to the wiping direction during cleaning). Consequently, the cleaning sheet of embodiment 2 can more consistently and reliably exhibit the excellent dirt removal performance described above when the second direction is used as the wiping direction during cleaning.

In yet another aspect (Aspect 3) of the present invention, in the cleaning sheet of Aspect 1 or 2, an opening area ratio of the plurality of openings is in a range of 4% to 60%.

The cleaning sheet of this embodiment 3 features multiple openings with an opening area ratio of at least 4%. The stepped edges of the openings allow the sheet to scrape away a predetermined amount of dirt, ensuring superior dirt removal performance. Furthermore, the cleaning sheet of this embodiment 3 features an opening area ratio of at most 60%, ensuring the desired rigidity for the cleaning sheet while also ensuring superior moisture release.

In yet another aspect (Aspect 4) of the present invention, in the cleaning sheet of aspects 1-3, the cleaning sheet has a first direction and a second direction that are orthogonal to each other, and the surface layer, on the wiping surface, has a plurality of openings located in a central region in the second direction having different opening shapes than the plurality of openings located in the end regions in the second direction.

The cleaning sheet of this type 4 can capture dirt such as garbage and dust according to their shapes and sizes on the wiping surface because the opening shapes of the multiple openings in the central area in the second direction (for example, the width direction) are different from the opening shapes of the multiple openings in the two end areas in the second direction. In particular, when the second direction is used as the wiping direction during cleaning, it can exert better dirt removal performance.

In yet another aspect (Aspect 5) of the present invention, in the cleaning sheet of any one of Aspects 1 to 4, the surface layer is formed of a fiber sheet, and the non-opening portion has a raised portion where fibers constituting the fiber sheet are raised.

The cleaning sheet of this embodiment 5 has a raised portion in the non-opening portion of the surface layer. The raised fibers of the raised portion can entangle and capture dirt such as garbage and dust on the cleaning object, thereby further demonstrating excellent dirt removal performance.

In yet another aspect (Aspect 6) of the present invention, in the cleaning sheet of Aspect 5, the raised fibers in the raised portion are hydrophobic.

The cleaning sheet of this embodiment 6 has hydrophobic fibers in the raised portion, so that the cleaning object can be wiped off even with relatively weak force. In addition, the fibers are not easily collapsed even when the cleaning sheet is wet, and the above-mentioned excellent dirt removal performance can be more reliably exerted.

In yet another aspect (Aspect 7) of the present invention, in the cleaning sheet of any one of Aspects 1 to 6, the surface of the surface layer forming the wiping surface has a static friction coefficient in the range of 0.20 to 0.40.

The cleaning sheet of aspect 7 has a static friction coefficient of 0.20 or greater on the wiping surface forming the surface layer, so it can reliably remove dirt, dust, and other contaminants from the cleaning object. Furthermore, the cleaning sheet of aspect 7 has a static friction coefficient of 0.40 or less on the wiping surface forming the surface layer, so it can remove the cleaning object even with relatively weak force.

In yet another aspect (Aspect 8) of the present invention, in the cleaning sheet of any one of Aspects 1 to 7, the surface layer is laminated on both sides of the water-retaining layer.

In the cleaning sheet of this embodiment 8, since the surface layer is laminated on both sides of the water-retaining layer, both sides of the cleaning sheet can be used as wiping surfaces, enabling more efficient cleaning.

In yet another aspect (Aspect 9) of the present invention, in the cleaning sheet of any of Aspects 1 to 8, the surface layer comprises a first surface opposing the water-retaining layer, and a second surface located opposite the first surface in the thickness direction, wherein the second surface has a higher mixing ratio of the hydrophobic material than the first surface.

Since the mixing ratio of the hydrophobic material on the second surface (i.e., the surface forming the wiping surface) of the surface layer of the cleaning sheet of this embodiment 9 is higher than the mixing ratio of the hydrophobic material on the first surface, the cleaning liquid released from the cleaning sheet can be appropriately controlled to achieve better water release properties.

In yet another aspect (aspect 10) of the present invention, the cleaning sheet of any one of aspects 1 to 9 is impregnated with a cleaning liquid.

Since the cleaning sheet of this embodiment 10 is impregnated with a cleaning solution, it can perform efficient or functional cleaning (e.g., cleaning with a sterilizing effect) according to the components of the cleaning solution (e.g., water, surfactant, alcohol, glycerin, etc.).

In yet another aspect (aspect 11) of the present invention, in the cleaning sheet of aspect 10, the water-retaining layer is impregnated with a larger amount of the cleaning liquid than the surface layer.

In the cleaning sheet of embodiment 11, the water-retaining layer is impregnated with a larger amount of cleaning liquid than the surface layer. The water-retaining layer retains a relatively large amount of cleaning liquid, allowing the cleaning liquid to be continuously released from the cleaning sheet, thereby achieving excellent water release properties more consistently.

In yet another aspect (Aspect 12) of the present invention, in the cleaning sheet of aspect 10 or 11, the amount of cleaning liquid impregnated in the water-retaining layer is 1.5 to 2.5 times the amount of cleaning liquid impregnated in the surface layer.

In the cleaning sheet of embodiment 12, the amount of cleaning solution impregnated into the water-retaining layer is 1.5 to 2.5 times the amount of cleaning solution impregnated into the surface layer. Therefore, an appropriate amount of cleaning solution can be continuously released from the cleaning sheet, further demonstrating excellent water release properties more consistently. [Effects of the Invention]

According to the present invention, a cleaning sheet is provided which has excellent dirt removal performance and water release properties and can continuously exert its excellent dirt removal performance.

Hereinafter, preferred embodiments of the cleaning sheet of the present invention will be described in detail with reference to the drawings.

[Cleaning Sheet] Figure 1 is a top view of a cleaning sheet 1 according to one embodiment of the present invention, viewed in the thickness direction _DT , in a unfolded state. Figure 2 is an enlarged perspective view of a key portion of the cleaning sheet 1. Figure 3 is an end view of the cleaning sheet 1 taken along line III-III in Figure 1. Furthermore, Figure 4 is an enlarged cross-sectional view of a key portion of the cleaning sheet 1. Figure 5 is an explanatory diagram schematically illustrating the operating mechanism of the cleaning sheet 1.

A cleaning sheet 1 according to one embodiment of the present invention is a thin, fiber-like structure that cleans surfaces such as floors, furniture, and appliances by wiping away dust and debris. As shown in FIG1 , the cleaning sheet 1 has a rectangular shape when viewed from above, having a long first direction D ₁ and a short second direction D ₂ perpendicular to the first direction D _1. The shape of the cleaning sheet 1 is not particularly limited and may be any shape (e.g., rectangular, square, trapezoidal, oblong, etc.) suitable for various applications.

As shown in Figures 1 to 3, the cleaning sheet 1 has a surface layer 2, a water-retaining layer 3, and a surface layer 4 as main components. The surface layer 2 forms a wiping surface for wiping the cleaning object. The water-retaining layer 3 is layered on the wiping surface (second surface) and the opposite surface (first surface) of the surface layer 2 and is impregnated with a cleaning solution. The surface layer 4 is layered on the surface of the water-retaining layer 3 opposite to the surface layer 2, forming the wiping surface opposite to the surface layer 2. That is, the cleaning sheet 1 has a three-layered structure in which a surface layer 2 on one side, a water-retaining layer 3, and a surface layer 4 on the other side are stacked in this order in the thickness direction _DT .

Then, in the cleaning sheet 1 of this embodiment, as shown in Figures 1 to 3, the surface layers 2 and 4 have, at least on the wiping surface, a plurality of openings 50 that penetrate the surface layers 2 and 4 in the thickness direction _DT , and non-opening portions 53 other than the openings 50. Furthermore, the water-retaining layer 3 is joined to the surface layers 2 and 4 at joints 61 and 62 at the end regions _A1 on one side and _A2 on the other side of the cleaning sheet ₁ in the second direction D2. Furthermore, the end regions 63 on one side and 64 on the other side in the second direction _D2 are joined in a form that does not contain the water-retaining layer 3. In other words, the water-retaining layer 3 is partially joined to the surface layers 2 and 4.

The cleaning sheet 1 thus constructed exhibits excellent dirt removal performance by having a plurality of openings 50 on at least the wiping surfaces of the surface layers 2 and 4. The stepped edges of the openings 50 scrape away dirt, dust, and other contaminants when wiping the object, thereby exhibiting excellent dirt removal performance. Furthermore, the cleaning sheet 1 exhibits excellent water release properties by having non-openings 53, such as those located between adjacent openings 50 and outside the plurality of openings 50, on at least the wiping surfaces of the surface layers 2 and 4. This allows the cleaning solution retained in the surface layers 2 and 4 and the water-retaining layer 3 to be appropriately released onto the object. Furthermore, in the cleaning sheet 1, since the water-retaining layer 3 is partially joined to the surface layers 2 and 4, the surface layers 2 and 4 can be easily moved in a staggered manner relative to the water-retaining layer 3. Therefore, as shown in Figure 5, even if the scraped dirt D is retained in the opening portion 50, the water-retaining layer 3 and the surface layer 2 are moved in a staggered manner relative to each other during the wiping operation ( _F2 and _F3 in Figure 5(a) respectively indicate the movement directions of the surface layer 2 and the water-retaining layer 3). While the dirt in the opening portion 50 is captured in the water-retaining layer 3 or at the boundary between the water-retaining layer 3 and the surface layer 2, it can be formed by the surface of the water-retaining layer 3 that is newly exposed on the bottom surface of the opening portion 50 (see Figure 5(b)). In this way, the cleaning sheet 1 can continue to exert the above-mentioned excellent dirt removal performance.

Furthermore, in this embodiment, the surface layers 2 and 4 are laminated on both sides of the water-retaining layer 3, thereby forming both sides of the cleaning sheet 1 as wiping surfaces. However, the present invention is not limited to this configuration; the cleaning sheet may also have the surface layer laminated on only one side of the water-retaining layer, with only that side of the cleaning sheet being the wiping surface. However, by laminating the surface layers on both sides of the water-retaining layer as in the above embodiment, both sides of the cleaning sheet can be used as wiping surfaces, resulting in the advantage of more efficient cleaning.

(Usage form) Although the usage form of the cleaning sheet 1 is not particularly limited, the cleaning sheet 1 uses the entire surface layers 2 and 4 as a wiping surface, and can be used to wipe the cleaning object in a manner similar to a rag or a wiping cloth. The central area _AC located in the center of the second direction _D2 of the surface layers 2 and 4 and extending in the first direction _D1 is used as the wiping surface, and the end area _A1 on one side of the second direction _D2 and the end area _A2 on the other side (i.e., the two end areas) are used as mounting portions for the holder. The two end areas are folded over and mounted on the front end of the holder, and can be used to wipe the cleaning object. In addition, when used in the manner described below, the holder is not particularly limited. For example, the holder may include: a gripping portion that the user grasps with his hand, and a rod-shaped holder made of resin (such as polypropylene, etc.) or metal (such as aluminum, etc.) located on the opposite side of the gripping portion and holding the front end of the cleaning sheet. Such a holder can be used by hand or on the floor.

Hereinafter, various components constituting the cleaning sheet of the present invention will be described in further detail using the cleaning sheet 1 of the above-described embodiment.

[Water-Retention Layer] In the cleaning sheet 1 described above, the water-retention layer 3 is positioned between the surface layers 2 and 4. It is formed from a hydrophilic nonwoven fabric that retains the cleaning solution within the cleaning sheet 1. Forming the water-retention layer 3 from a hydrophilic nonwoven fabric allows the cleaning sheet 1 to appropriately release the cleaning solution retained in the water-retention layer 3 toward the object being cleaned, via the non-opening portions 53 of the surface layers 2 and 4.

The hydrophilic nonwoven fabric forming the water-retaining layer 3 is not particularly limited as long as it can retain the cleaning liquid, and any hydrophilic nonwoven fabric can be used. Such a hydrophilic nonwoven fabric only needs to be hydrophilic, and therefore may be a nonwoven fabric composed solely of hydrophilic fibers, a nonwoven fabric composed of hydrophilic fibers and hydrophobic fibers, or a nonwoven fabric composed solely of hydrophobic fibers that has been subjected to a hydrophilizing treatment.

As for such hydrophilic nonwovens, there is no particular limitation. For example, airflow formed nonwovens, wet nonwovens, water needle nonwovens, spunbond nonwovens, meltblown nonwovens, thermally bonded nonwovens (such as hot air nonwovens, point bonded nonwovens, etc.), chemically bonded nonwovens, etc., but airflow formed nonwovens are ideal.

Furthermore, the fibers that comprise the hydrophilic nonwoven fabric are not particularly limited, provided they do not hinder the effects of the present invention. Examples include cellulose-based fibers and synthetic fibers. These cellulose-based fibers and synthetic fibers may be used alone or in combination. Furthermore, a binder (e.g., EVA, SBR, etc.) may also be used. Examples of cellulose-based fibers include natural cellulose-based fibers such as pulp, cotton, and linen; and regenerated cellulose-based fibers such as rayon, lyocell, and cuprammonium rayon. These fibers may be used alone or in combination of two or more types. In addition, synthetic fibers include: polyolefin fibers such as polyethylene (PE) and polypropylene (PP); polyester fibers such as polyethylene terephthalate (PET) and polypropylene terephthalate (PTT); polyvinyl alcohol fibers such as vinyl; polypropylene fibers such as polyacrylonitrile; polyurethane (PU) fibers; polyamide fibers such as nylon, etc. These fibers may be used alone or in combination of two or more types. Furthermore, the form of the synthetic fiber is not particularly limited. For example, core-sheath composite fibers such as PP (core)/PE (sheath), high-melting-point PP (core)/low-melting-point PP (sheath), and PET (core)/PE (sheath); side-by-side composite fibers; and fibers with irregular cross-sections such as flat, Y-shaped, and C-shaped. In addition, when the nonwoven fabric is formed solely from hydrophobic synthetic fibers, the synthetic fibers can be hydrophilized using a hydrophilizing agent before forming the nonwoven fabric, or the nonwoven fabric can be hydrophilized using a hydrophilizing agent after forming.

The thickness and basis weight of the hydrophilic nonwoven fabric forming the water-retaining layer 3 are not particularly limited as long as the effects of the present invention are not hindered. Although any thickness and basis weight may be employed, from the perspectives of impregnation and release of cleaning chemicals, a basis weight in the range of 15 g/ ^m² to 100 g/ ^m² is ideal, and a basis weight in the range of 30 g/ ^m² to 80 g/ ^m² is even more ideal.

In addition, in the present invention, the water-retaining layer can be formed of any fiber sheet (such as woven fabric, knitted fabric, etc.) other than hydrophilic non-woven fabric, or a resin sheet with water-retaining properties, as long as it can retain the cleaning liquid.

Furthermore, in the cleaning sheet 1 described above, the water-retaining layer 3 is formed shorter than the second direction length of the surface layers 2 and 4, as shown in Figures 1 to 3, and is joined to the surface layers 2 and 4 at both ends in the second direction _D2 . Specifically, as shown in Figures 1 to 3, in the cleaning sheet 1, the surface layer 2 is formed shorter than the surface layer 4 in the second direction length, and the portions where both ends of the surface layer ₂ in the second direction D2 overlap with both ends of the water-retaining layer ₃ in the second direction D2 in the thickness direction _DT are joined by respective joints extending in the first direction _D1 between the water-retaining layer 3 and the surface layers 2 and 4 (i.e., joints 61 on one side in the second direction _D2 and joints 62 on the other side in Figures 1 to 3). In addition, the surface layer 4 is folded toward the surface side on which the surface layer 2 and the water-retaining layer ₃ are stacked at both ends in the second direction _D2 located on the outer sides of the above-mentioned joints 61 and 62 (i.e., the end 63 on one side and the end 64 on the other side in the second direction D2 in Figures 1 to 3), and the folded portions are joined.

Furthermore, in the above-mentioned cleaning sheet 1, the joints 61 and 62 between the water-retaining layer 3 and the surface layers 2 and 4 are located in the end region A1 on one side and the end region _A2 on the other side of the cleaning sheet ₁ in the second direction _D2 , as shown in Figure 1. That is, the water-retaining layer 3 and the surface layers 2 and 4 are joined in the two end regions of the cleaning sheet 1 in the second direction _D2 . Because the cleaning sheet 1 has the water-retaining layer 3 and the surface layers 2 and 4 joined at both end regions in the second direction _D2 , while maintaining its structure as a cleaning sheet, in the central region _AC in the second direction _D2 , as shown in Figure 5, the surface layers 2 and 4 can easily move relative to the water-retaining layer 3 in the second direction _D2 (ideally, the direction corresponding to the wiping direction during cleaning). Therefore, when the second direction _D2 is used as the wiping direction during cleaning, the excellent dirt removal performance described above can be more continuously and reliably exerted.

Here, the central region _AC in the second direction _D2 is a region extending in the first direction D1 so as to include the central portion of the cleaning sheet ₁ in the second direction _D2 , as shown in FIG1 , and is divided into a region having approximately 2/4 of the length of the cleaning sheet 1 in the second direction (the entire length in the second direction). The end region A1 on one side in the _second direction _D2 and the end region _A2 on the other side (i.e., the two end regions) are regions sandwiching the central region _AC from both sides in the second direction _D2 and adjacent to the central region _AC in the second direction _D2 , as shown in FIG1 , and are respectively divided into regions having approximately 1/4 of the length of the cleaning sheet 1 in the second direction.

Furthermore, as long as the surface layers 2 and 4 can easily move relative to the water-retaining layer ₃ in the second direction _D2 in the central region AC of the cleaning sheet 1, which serves as the wiping surface, and are staggered relative to each other in the second direction _D2 , the water-retaining layer 3 and the surface layers 2 and 4 may be partially joined in the central region _AC , or may not be joined in the central region _AC , or may be joined only in the end regions.

The arrangement of the joints 61, 62 between the water-retention layer 3 and the surface layers 2, 4 is not particularly limited as long as it does not hinder the effects of the present invention. For example, the joints 61, 62 may be arranged at predetermined intervals in the second direction _D2 and in a plurality of arbitrary linear configurations (e.g., straight lines, dashed lines, dotted lines, wavy lines, spirals, Ω shapes, etc.) extending along the first direction _D1 . In particular, from the perspective of improving dirt removal performance, the joints 61, 62 are preferably arranged at intervals of 10 mm to 150 mm in the second direction _D2 and in a plurality of linear configurations extending in a straight line along the first direction _D1 .

In addition, the means for forming the joints 61 and 62, that is, the means for joining the water-retaining layer 3 and the surface layers 2 and 4 is not particularly limited as long as it does not hinder the effects of the present invention, and any joining means such as hot melt bonding, ultrasonic bonding, and bonding using an adhesive can be adopted.

[Surface Layer] In the cleaning sheet 1 described above, the surface layers 2 and 4 are arranged so as to sandwich the water-retaining layer 3 in the thickness direction _DT . These layers are formed from a hydrophobic nonwoven fabric that forms a wiping surface for wiping the object being cleaned and releases cleaning liquid. While the surface layers 2 and 4 can also be formed from a hydrophilic nonwoven fabric, using a hydrophobic nonwoven fabric not only allows the object to be wiped even with relatively weak force, but also prevents the constituent fibers from collapsing even when the cleaning sheet is wet, resulting in superior dirt removal performance.

The hydrophobic nonwoven fabric forming the surface layers 2 and 4 is not particularly limited as long as it can form the wiping surface of the cleaning sheet 1, and any hydrophobic nonwoven fabric can be used. Such a hydrophobic nonwoven fabric only needs to have hydrophobic properties, so it can be formed solely from hydrophobic fibers or a nonwoven fabric formed from a combination of hydrophilic and hydrophobic fibers.

As for such hydrophobic nonwovens, there is no particular limitation. For example, water-jet nonwovens manufactured by a water jet method (water interlacing method), airflow forming nonwovens, spunbond nonwovens, meltblown nonwovens, thermally bonded nonwovens (for example, hot air nonwovens, point-bonded nonwovens, etc.), chemically bonded nonwovens, etc., can be cited. However, nonwovens manufactured by dry methods such as hot air nonwovens and point-bonded nonwovens and water-jet nonwovens are ideal, and water-jet nonwovens are particularly ideal. Because nonwoven fabrics and water-needle nonwoven fabrics manufactured using such a dry process have the property of being easily stretched (in addition, nonwoven fabrics manufactured using a dry process have the property of being easily stretched in the CD direction because the fibers are oriented in the MD direction), if the surface layers 2 and 4 are formed using such a nonwoven fabric, the surface layers 2 and 4 can easily move away from the water-retaining layer 3, and the above-mentioned excellent dirt removal performance can be more continuously and reliably exerted.

Furthermore, the fibers constituting the hydrophobic nonwoven fabric are not particularly limited as long as they do not hinder the effects of the present invention. For example, the synthetic fibers and cellulose-based fibers exemplified as the fibers constituting the hydrophilic nonwoven fabric forming the water-retaining layer 3 described above can be used. Furthermore, when the hydrophobic nonwoven fabric is composed of hydrophobic fibers and hydrophilic fibers, the hydrophobic fibers are present at a ratio of 50% by mass or greater, and preferably at a ratio of 70% by mass or greater, relative to the total mass of the nonwoven fabric.

The thickness, basis weight, etc. of the hydrophobic nonwoven fabric forming the surface layers 2 and 4 are not particularly limited as long as the effects of the present invention are not hindered. Although any thickness, basis weight, etc. can be adopted, from the perspectives of dirt removal performance of the surface layers 2 and 4 and release of cleaning liquid from the non-opening portion 53, the basis weight of each surface layer 1 is ideally within the range of 10 g/ ^m2 to 80 g/ ^m2 , and more ideally within the range of 30 g/ ^m2 to 60 g/ ^m2 .

In the present invention, the surface layer may be formed of any fiber sheet (e.g., woven fabric, knitted fabric, etc.), porous resin sheet, etc. other than hydrophobic nonwoven fabric, as long as it forms the wiping surface of the cleaning sheet and can release the cleaning liquid.

(Openings) In the cleaning sheet 1 described above, the surface layers 2 and 4 have, as shown in FIG. 1 to FIG. 3 , a plurality of openings 50 to 52 penetrating the surface layers 2 and 4 in the thickness direction _DT , and non-opening portions 53 other than the openings, all over the surface layers 2 and 4. Furthermore, as shown in Figures 1 to 3, the plurality of openings 50-52 include: an opening 50, which is widely dispersed over at least the entirety of a central region _AC in the second direction _D2 , which serves as the wiping surface, and a portion of both end regions in the second direction _D2 ; and openings 51 and 52, which are dispersed in each of the end regions in the second direction _D2 (i.e., end region _A1 on one side and end region _A2 on the other side of the second direction _D2 ). As shown in Figure 1, the opening 50 and the openings 51 and 52 have different opening shapes. Furthermore, the opening 50 and the openings 51 and 52 have the same opening shape when the openings are formed. In subsequent manufacturing processes, the opening shapes are changed by stretching the non-woven fabric, resulting in the aforementioned different opening shapes.

The method for forming the plurality of openings 50-52 is not particularly limited. Examples include water jetting, which involves shooting water streams at a net having a plurality of opening patterns; needle punching, which involves perforating a net with a plurality of needle-like members; and cutting, which involves cutting a circular shape using a cutting tool such as a knife. Of these, water jetting and needle punching are preferred because they facilitate forming the raised portion 54 described below in the non-opening portion 53.

In the cleaning sheet of the present invention, the opening area ratio of the multiple openings is not particularly limited as long as it does not hinder the effectiveness of the present invention, but is ideally within the range of 4% to 60%. If the opening area ratio of the multiple openings is 4% or greater, the step difference at the edge of the openings can scrape off a predetermined amount of dirt, ensuring superior dirt removal performance. Furthermore, if the opening area ratio of the multiple openings is 60% or less, superior moisture release can be more reliably achieved while maintaining the desired rigidity of the cleaning sheet. Furthermore, the opening area ratio of the multiple openings is ideally within the range of 4% to 50%, and even more ideally, within the range of 4% to 35%.

The opening area of multiple openings can be measured as follows. Using a microscope (Keyence VHX-7000 Digital Microscope) at 50x magnification, observe the surface of the sample being measured (i.e., a cleaning sheet, nonwoven fabric forming a surface layer, etc.). Using the microscope's attached measuring tool (with the brightness set between 0 and 70), measure the total area ratio of the black portion of the magnified image. This total area ratio of the measured black portion serves as the opening area ratio of the multiple openings.

In the cleaning sheet of the present invention, the opening density of the plurality of openings is not particularly limited as long as it does not hinder the effect of the present invention, but is preferably in the range of 1 opening/cm ² to 100 openings/cm ² from the perspective of dirt removal performance.

Furthermore, the shape of the opening is not particularly limited; for example, any shape can be adopted, such as an ellipse, circle, triangle, square, polygon, or star. Furthermore, the dimensions of the opening are not particularly limited. For example, a circular opening can have a diameter of 1 mm to 5 mm; an elliptical opening can have a major diameter of 1 mm to 5 mm and a minor diameter of 0.1 mm to 4 mm.

Furthermore, in the cleaning sheet of the present invention, the surface layer may be formed such that the opening shapes of the plurality of openings in the central region in the second direction differ from the opening shapes of the plurality of openings in the end regions in the second direction. If the opening shapes of the plurality of openings in the central region in the second direction differ from the opening shapes of the plurality of openings in the end regions in the second direction, dirt, dust, and other contaminants can be captured according to their shape and size, thereby achieving even better dirt removal performance, particularly when the second direction is used as the wiping direction during cleaning.

For example, when the multiple openings in the two end areas in the second direction which is the wiping direction during cleaning are in the shape of an opening that is longer in the first direction and has a smaller aspect ratio or a circular opening, and the multiple openings in the central area in the second direction are in the shape of an opening that is longer in the first direction and has a larger aspect ratio, dust and garbage can be captured by the multiple openings in the two end areas, and garbage that escapes from the multiple openings in the above-mentioned two end areas can be captured by the multiple openings in the central area.

(Non-Opening Portion) In the cleaning sheet 1 described above, the surface layers 2 and 4, as shown in Figures 1 to 3, have a non-opening portion 53 extending over their entire surface in addition to the plurality of opening portions 50 to 52 described above.

Furthermore, in the cleaning sheet 1, as shown in Figure 4, the fibers constituting the hydrophobic nonwoven fabric of the surface layers 2 and 4 have raised sections 54 in the non-opening sections 53. The presence of raised sections 54 in the non-opening sections 53 of the surface layers 2 and 4 allows the raised fibers 54F of the raised sections 54 to entangle and capture dirt, such as dust, on the cleaning object, thereby further enhancing excellent dirt removal performance.

In addition, in this embodiment, although the raised portion 54 is formed by the constituent fibers of the hydrophobic nonwoven fabric forming the surface layers 2 and 4, in the present invention, the raised portion of the surface layer can also be formed by the constituent fibers of a fiber sheet such as nonwoven fabric, woven fabric, or knitted fabric.

As used herein, the term "raised portion" refers to a portion where, when a fiber sheet (e.g., nonwoven, woven, or knitted fabric) forming the surface layer is cut in the thickness direction and the cut ends of the constituent fibers (i.e., raised fibers) exposed on the surface of the fiber sheet are present within a 5 mm area parallel to the sheet surface, when the cut surface is magnified and observed. In the cleaning sheet of the present invention, the raised portion is preferably present in a substantially uniform pattern throughout the non-opening portion of the fiber sheet, for improved dirt removal performance. For example, it is ideal to have one or more fibers within a 1 mm area parallel to the sheet surface.

Furthermore, in the cleaning sheet 1 described above, because the surface layers 2 and 4 are formed of a hydrophobic nonwoven fabric, the raised fibers 54F of the raised portion 54 are hydrophobic. The hydrophobicity of the raised fibers 54F of the raised portion 54 not only allows the cleaning object to be wiped away with relatively little force, but also prevents the fibers from collapsing even when the cleaning sheet 1 is wet, ensuring the excellent dirt removal performance described above.

In the present invention, the term "the raised fibers are hydrophobic" means that the mass ratio of the hydrophobic fibers among all the raised fibers is 50 mass % or more, and preferably the mass ratio of the hydrophobic fibers is 70 mass % or more.

Furthermore, in the present invention, the surface layer forming the wiping surface preferably has a static friction coefficient within the range of 0.20 to 0.40. If the surface forming the wiping surface of the surface layer has a static friction coefficient of 0.20 or higher, dirt, dust, and other contaminants on the cleaning object can be effectively wiped away. If the surface forming the wiping surface of the surface layer has a static friction coefficient of 0.40 or lower, the cleaning object can be wiped away even with relatively weak force.

In addition, the static friction coefficient of the surface layer can be measured using a commercially available friction needle (e.g., a portable tribometer manufactured by Nissin Machinery Co., Ltd.).

In the present invention, the surface layer comprises a first surface opposing the water-retaining layer and a second surface located opposite the first surface in the thickness direction. Furthermore, the mixing ratio of the hydrophobic material (e.g., hydrophobic fibers) on the second surface is preferably higher than that on the first surface. If the mixing ratio of the hydrophobic material on the second surface (i.e., the surface forming the wiping surface) of the surface layer is higher than that on the first surface, the release of the cleaning solution from the cleaning sheet is appropriately controlled, resulting in better water release.

Furthermore, in the present invention, the cleaning sheet can be impregnated with the cleaning liquid during manufacture, or it can be impregnated without impregnation and then impregnated with the cleaning liquid upon use. However, in the former case, a cleaning sheet pre-impregnated with the cleaning liquid offers the advantage of being able to perform efficient or functional cleaning (e.g., providing a sterilizing effect) corresponding to the composition of the cleaning liquid (e.g., water, surfactant, alcohol, glycerin, etc.).

Furthermore, in the present invention, it is ideal that the water-retaining layer is impregnated with a greater amount of cleaning liquid than the surface layer. If the water-retaining layer is impregnated with a greater amount (mass) of cleaning liquid than the surface layer, the water-retaining layer retains a relatively large amount of cleaning liquid. This facilitates more sustained release of the cleaning liquid from the cleaning sheet, thereby achieving more sustained excellent water release.

In addition, when the surface layer is laminated on both sides of the water-retaining layer, the amount of cleaning liquid impregnated on the surface layer is not the total impregnation amount of the two surface layers, but the impregnation amount of each surface layer.

Furthermore, in the present invention, it is ideal that the amount of cleaning solution impregnated into the water-retaining layer is 1.5 to 2.5 times the amount impregnated into the surface layer. If the amount of cleaning solution impregnated into the water-retaining layer is 1.5 to 2.5 times the amount impregnated into the surface layer, an appropriate amount of cleaning solution can be continuously released from the cleaning sheet, further enabling more sustained and excellent water release.

Furthermore, the cleaning sheet of the present invention is not limited to the above-described embodiments and is subject to appropriate combinations, substitutions, and modifications without departing from the purpose and objectives of the present invention. Furthermore, in this specification, ordinal numbers such as "first" and "second" are used to distinguish the items to which they are assigned, and do not indicate the order, priority, or importance of the items.

1: Cleaning sheet 2: Surface layer on one side 3: Water-retaining layer 4: Surface layer on the other side 50: Opening 51, 52: Opening 53: Non-opening 54: Raised portion 61, 62: Joint 63: End of one side ₆₄ : End of the other side D1: First direction _D2 : Second direction _A1 : End area on one side _A2 : End area on the other side _AC : Central area

FIG1 is a top view of a cleaning sheet 1 according to one embodiment of the present invention, viewed in the thickness direction _DT, in a unfolded state. FIG2 is an enlarged perspective view of a key portion of the cleaning sheet 1. FIG3 is an end view of the cleaning sheet 1 taken along line III-III in FIG1 . FIG4 is an enlarged cross-sectional view of a key portion of the cleaning sheet 1. FIG5 is an explanatory diagram schematically illustrating the operating mechanism of the cleaning sheet 1.

1: Cleaning sheet

2: Surface layer on one side

3: Water retaining layer

4: Surface layer on the other side

50:Opening part

51:Opening part

52:Opening part

53:Non-opening part

61: Joint

62: Joint

63: End of one side

64: End of the other side

D ₁ : 1st direction

D ₂ : Second direction

_A1 : End area on one side

_A2 : The end area on the other side

A _C : Central region

Claims (11)

A cleaning sheet comprises a water-retaining layer and a surface layer, the surface layer being laminated on at least one side of the water-retaining layer to form a wiping surface. The cleaning sheet is characterized by: The surface layer, at least on the wiping surface, has a plurality of openings extending through the surface layer in the thickness direction, and non-opening portions other than the openings; The water-retaining layer and the surface layer are partially bonded; The surface layer is formed of a fiber sheet, and the non-opening portions have a raised portion where fibers constituting the fiber sheet form raised fibers. The cleaning sheet of claim 1, wherein the cleaning sheet has a first direction and a second direction that are orthogonal to each other, and the water-retaining layer and the surface layer are joined at both end regions in the second direction. In the cleaning sheet of claim 1 or 2, an opening area ratio of the plurality of openings is within a range of 4% to 60%. The cleaning sheet of claim 1, wherein the cleaning sheet has a first direction and a second direction that are orthogonal to each other, and wherein the plurality of openings in the central region of the surface layer on the wiping surface in the second direction have different opening shapes than the plurality of openings in the end regions in the second direction. The cleaning sheet of claim 1, wherein the raised fibers of the raised portion are hydrophobic. The cleaning sheet of claim 1, wherein the surface of the surface layer forming the wiping surface has a static friction coefficient in the range of 0.20 to 0.40. The cleaning sheet of claim 1, wherein the surface layer is laminated on both sides of the water-retaining layer. The cleaning sheet of claim 1, wherein the surface layer comprises a first surface opposing the water-retaining layer and a second surface located opposite the first surface in the thickness direction; The second surface has a higher mixing ratio of the hydrophobic material than the first surface. The cleaning sheet of claim 1, wherein the cleaning sheet is impregnated with a cleaning liquid. The cleaning sheet of claim 9, wherein the amount of cleaning liquid impregnated into the water-retaining layer is greater than the amount of cleaning liquid impregnated into the surface layer. The cleaning sheet of claim 9 or 10, wherein the amount of cleaning solution impregnated into the water-retaining layer is 1.5 to 2.5 times the amount of cleaning solution impregnated into the surface layer.