TWI891708B - Cleaning dry sheet and manufacturing method of cleaning dry sheet - Google Patents

Abstract

An object of the present invention is providing a cleaning dry sheet 100 with a multi-layer structure which includes an outer fiber layer 11 that forms a surface and has hydrophobic fibers, and an inner fiber layer 12 that is sandwiched between the outer fiber layers 11, wherein a cellulose nanofiber solution is applied such that the outer fiber layer 11 contains 0.2g/m² or more and 4.0g/m² or less of cellulose nanofibers, and heat-drying is performed.

Description

Dry dust-removing paper for cleaning and method for manufacturing the same

The present invention relates to dry dust-removing paper for cleaning and a method for manufacturing the dry dust-removing paper for cleaning.

From the perspective of dust and dirt capture or rigidity, dry dust removal paper used for cleaning floors, etc., has hydrophobic fibers on the surface (see, for example, Patent Document 1).

[Prior Art Literature]

[Patent Literature]

[Patent Document 1] Japanese Patent Application Publication No. 2014-004328

However, when used on dry dust paper with hydrophobic fibers on the surface, it has the problem of not being able to absorb water stains. While this problem can be solved by mixing hydrophilic agents such as higher alcohols into the hydrophobic fibers, the amount of water absorbed is difficult to control and the manufacturing cost increases.

The object of the present invention is to provide a dry dust removal paper for cleaning that has easy adjustment of water absorption and low manufacturing cost.

To solve the aforementioned problem, the invention described in claim 1 is a dry dust removal paper for cleaning, which is a non-woven fabric having hydrophobic fibers on its surface, wherein:

The surface of the nonwoven fabric is coated with cellulose nanofiber (CNF) at a density of 0.2 g/ ^m2 or more and 4.0 g/m2 or ^less .

The invention described in claim 2 is the dry dust removal paper for cleaning as described in claim 1, wherein:

The aforementioned dry dust removal paper for cleaning has a multi-layer structure, which comprises an outer layer forming the surface of the dust removal paper and an inner layer sandwiched between the outer layers.

The aforementioned inner layer comprises polypropylene fibers.

The invention described in claim 3 is the dry dust removal paper for cleaning as described in claim 1 or 2, wherein:

The outer layer constituting the aforementioned surface contains more than 80% polyethylene terephthalate fibers.

The invention described in claim 4 is a dry dust removal paper for cleaning as described in any one of claims 1 to 3, wherein:

The aforementioned cellulose nanofibers are TEMPO-oxidized cellulose nanofibers.

The invention described in claim 5 is a method for manufacturing dry dust-removing paper for cleaning, which comprises the following steps:

The coating step is to coat the cellulose nanofiber solution on the nonwoven fabric so that the coating amount of the cellulose nanofiber is greater than or equal to 0.2 g/ ^m2 and less than or equal to 4.0 g/ ^m2 ; and

The drying step is to heat dry the nonwoven fabric.

The invention described in claim 6 is a method for manufacturing dry dust-removing paper for cleaning as described in claim 5, wherein:

The aforementioned cellulose nanofibers are TEMPO-oxidized cellulose nanofibers.

The present invention provides a dry dust-removing paper for cleaning that can easily adjust its water absorption capacity and has low manufacturing costs, as well as a method for manufacturing the dry dust-removing paper for cleaning.

11: Outer layer (outer fiber layer)

12: Inner layer (inner fiber layer)

20: Embossing Department

21: Embossing

21a: 1st convex part

21b: 2nd convex part

22: Embossing

22a: 1st concave part

22b: 2nd concave part

23:Middle part

30: Non-embossed part

31: concave part

100: Clean with dry dust paper

200:Cleaning tools

201: Head

201a: Long edge

202: Handle

H: Flat surface

S: Folding part

Figure 1 shows the state of the dry dust removal paper used for cleaning according to this embodiment when in use.

Figure 2 is a plan view showing an example of dry dust paper for cleaning.

Figure 3 is a cross-sectional view taken along line III-III in Figure 2.

Figure 4 is an enlarged view of section A in Figure 2.

Figure 5 is a cross-sectional view taken along line V-V in Figure 4.

The following describes the specific aspects of the dry dust removal paper 100 for cleaning according to an embodiment of the present invention based on Figures 1 to 5. However, the technical scope of the present invention is not limited to the illustrated examples.

For convenience, the following descriptions are made using the X, Y, and Z directions, as well as front and back, left and right, and up and down, as shown in Figures 1 to 5.

[Implementation form]

FIG1 is a diagram showing the state of the dry dust removal paper 100 for cleaning according to this embodiment when in use.

As shown in Figure 1, the dry dust paper 100 is replaceably attached to a cleaning tool 200, and has an outer layer ¹¹ coated with 0.2 to 4.0 g/ ^m² of cellulose nanofiber (CNF). The cleaning tool 200 includes a rectangular, flat head 201 and a handle 202 attached to the upper surface of the head 201. If the CNF coating amount is less than 0.2 g/ ^m² , the water absorption of the dry dust paper 100 is not improved. Furthermore, if the CNF coating amount exceeds 4.0 g/ ^m² , the drying step during the manufacturing process becomes more burdensome, which is not desirable.

The dry dust paper 100 for cleaning covers the bottom surface of the head 201 of the cleaning tool 200 to form the cleaning surface. It is folded along the long edge 201a of the head 201 of the cleaning tool and engages with the top surface of the head 201, in an installed state.

Furthermore, the so-called long edges 201a refer to the edges along the long sides of the head 201. In other words, they refer to the two longer edges among the four edges of the rectangular head 201.

FIG2 is a plan view showing an example of dry dust removal paper 100 for cleaning according to this embodiment.

As shown in FIG2 , the cleaning dry dust paper 100 is rectangular and elongated in the X direction. For example, the length in the X direction (longitudinal direction) is 250 mm to 300 mm, preferably 260 mm to 290 mm, and the length in the Y direction (shortitudinal direction) is 180 mm to 230 mm, preferably 200 mm to 210 mm.

Figure 3 is a cross-sectional view taken along line III-III in Figure 2.

The dry dust paper 100 for cleaning is made of, for example, multiple sheets of nonwoven fabric. As shown in FIG3 , it has a three-layer structure comprising outer layers 11, 11 forming the surface layer of the dry dust paper 100, and an inner layer 12 sandwiched between the outer layers 11, 11.

(Outer layer: outer fiber layer)

The outer layer 11 is a fiber layer that forms the outer surface of the dry dust removal paper 100 for cleaning.

The outer layer 11 is primarily composed of hydrophobic fibers. Hydrophobic fibers can be chemical fibers primarily composed of PET (polyethylene terephthalate), PP (polypropylene), or PE (polyethylene).

The PET fiber content of the outer layer 11 is preferably 80% or greater, and the fiber diameter is preferably 3.3 dtex or greater. A fiber diameter of 3.3 dtex or greater improves the fiber's stiffness (cushioning properties), allowing for easy handling with minimal force.

The outer layer 11 preferably has a weight per unit area of 20 g/ ^m2 to 80 g/ ^m2 , particularly preferably 30 g/ ^m2 to 60 g/ ^m2 . A weight per unit area of dust removal paper below 20 g/ ^m2 may not be able to hold dirt, while a weight exceeding 80 g/ ^m2 may not be flexible enough.

Furthermore, by applying 0.2 g/ ^m² to 4.0 g/ ^m² of CNF to the outer layer 11, the specific surface area is increased, and even the hydrophobic fibers have excellent water absorption. The CNF in the outer layer 11 can be applied at any location: substantially the entire surface of the dry dust removal paper 100, only to the edges or the center, or even scattered.

In addition, the outer surface of the outer layer 11 serves as the surface of the dry dust removal paper 100 for cleaning.

Furthermore, CNF is preferably applied to both sides of the cleaning paper 100. In this case, since it is attached to the cleaning tool 200, one side is in contact with the floor. When it becomes dirty, the cleaning paper 100 is flipped over and attached to the cleaning tool 200, so that the other side is in contact with the floor. This allows the user to use the cleaning paper 100 for a longer cleaning period.

(Inner layer: inner fiber layer)

The inner layer 12 is an inner fiber layer sandwiched between the outer layers 11, 11.

The inner layer 12 preferably contains a hydrophobic fiber such as polypropylene spunbond as a reinforcement layer. The weight per unit area of the inner layer 12 is preferably between 5g/ ^m² and 50g/ ^m² , preferably between 10g/ ^m² and 30g/ ^m² . By setting the weight per unit area of the inner layer 12 to between 5g/ ^m² and 50g/ ^m² , the embossed shape can be formed without removing the grain during hot embossing. Furthermore, the embossed shape is easily maintained when cleaning wooden floors.

Furthermore, when cleaning hard surfaces such as tiles, the weight per unit area of the inner layer 12 is not limited to the above range and can be increased.

Furthermore, in the dry dust paper 100 for cleaning, the fibers at the boundary between the outer layers 11, 11 and the inner layer 12 are intertwined, making it easier to form the embossed shape through heat embossing. Furthermore, the embossed shape is easier to maintain during cleaning.

The dust paper structure of the above-described dry dust paper 100 is merely an example, and the number of layers and the fibers contained in each layer can be modified as appropriate. For example, the dry dust paper 100 is not limited to a multi-layer structure and can primarily be a single-layer structure comprising a non-woven fabric formed of hydrophobic fibers.

[CNF]

CNF is a material with water-retention properties, high safety, and its aqueous solution exhibits volatility. It is a fine cellulose fiber obtained by defibrinating paper pulp. It generally refers to cellulose microfibers with fiber widths on the nanoscale (between 1 nm and 1000 nm), preferably with an average fiber width of 100 nm or less. Average fiber width can be calculated using, for example, the average, median, or multiplicity of a given number.

(Pulp fiber that can be used as CNF)

Pulp fibers that can be used as CNF include: broadleaf pulp (LBKP), softwood pulp (NBKP) and other chemical pulps; bleached thermomechanical pulp (BTMP), stone-ground wood pulp (SGP), pressurized stone-ground wood pulp (PGW), refined groundwood pulp (RGP), chemical groundwood pulp (CGP), thermo-ground wood pulp (TGP), groundwood pulp (GP), thermomechanical pulp (TMP), chemical thermo-ground pulp (CTMP), refined mechanical pulp (RGP), Waste paper pulp (e.g., recycled paper pulp; RMP), mechanical pulp such as tea waste, kraft envelope waste, magazine waste, newspaper waste, leaflet waste, office waste, corrugated paper, new paper waste, drawing waste, molding waste, tomb ticket waste, and wood pulp waste, and deinked paper pulp (DIP) obtained by deinking waste paper pulp. These pulps may be used individually or in combination, without prejudice to the effects of the present invention.

(Fiber removal method)

The defibration methods used in CNF production include, but are not limited to, mechanical methods such as high-pressure homogenizers, fine fluid homogenizers, grinder grinding, bead milling, and ultrasonic defibration.

Furthermore, CNF that has been mechanically treated (unmodified) using the aforementioned defibration method, or unmodified CNF, has higher thermal stability than CNF modified with functional groups such as phosphate or carboxymethyl, and can therefore be used in a wider range of applications. However, CNF modified with functional groups such as phosphate or carboxymethyl can also be used in the present invention.

Alternatively, for example, pulp fibers that have been mechanically defibrated can be chemically treated with carboxymethylation or enzymes. Chemically treated CNFs include TEMPO-oxidized CNFs, phosphate-esterified CNFs, phosphite-esterified CNFs, and other iCNFs (individualized CNFs) (single nanofibers) with diameters of 3 to 4 nm.

Alternatively, CNF may be obtained by subjecting CNF to chemical or enzyme treatment alone, or by subjecting CNF to chemical or enzyme treatment and then subjecting it to mechanical defibration.

[CMC]

In addition, to prevent CNF from agglomerating in the solution, carboxymethyl cellulose (hereinafter referred to as CMC), a water-soluble polymer, can be added.

When CNF is added to an aqueous solvent, the CNF microfibers aggregate and bind together. However, by adding CMC, the CNF and CMC coexist, allowing the OH groups of the CNF to form hydrogen bonds with the OH groups of the CMC. This prevents CNF aggregation through electrostatic interactions and steric effects within the molecular chains, allowing the CNF to be evenly dispersed in the solution.

Furthermore, CMC is a preferred material because it can be derived from cellulose, is slowly biodegradable, and can be incinerated after use, making it an extremely environmentally friendly material. However, water-soluble polymers other than CMC can also be used as long as they can prevent CNF from agglomerating in solution.

When CMC is added, the solution preferably contains 93.000 to 99.790 mass% of water, 0.002 to 0.020 mass% of CNF, and 0.100 to 1.000 mass% of CMC, with the total solution being 100.000 mass%.

Furthermore, the fiber aggregate substrate may be impregnated with the solution in an amount ranging from 100% to 500% by mass relative to the dry weight of the fiber aggregate substrate, but preferably, the impregnation amount is 200% to 350% by mass.

(Folding)

Returning to Figure 2, the portion of the dry dust paper 100 that is folded along the long edge 201a of the head 201 of the cleaning tool 200 is referred to as the folded portion S.

The folds S are pre-positioned to match the head 201 of the cleaning tool 200. Specifically, two rows of folds S extending in the X direction are provided at predetermined positions on the cleaning paper 100 in the Y direction. To facilitate user identification, the folds S can be pre-printed on the cleaning paper 100 with corresponding straight lines, or fold lines corresponding to the folds S can be formed on the cleaning paper 100.

In addition, a plurality of non-embossed sections 30 are arranged at predetermined intervals along the folded portion S of the cleaning dry dust paper 100 in the X direction. The entire cleaning dry dust paper 100, except for the area where the non-embossed sections 30 are arranged, is provided with the embossed sections 20.

Thus, in the dry dust paper 100 for cleaning, the embossed portions 20 and the non-embossed portions 30 are alternately arranged at positions corresponding to the long edge 201a of the head 201 of the cleaning tool 200.

(Embossing Department)

The embossed portion 20 is the portion of the dry cleaning paper 100 where the cleaning paper is compressed in the thickness direction.

The embossed portion 20 can be formed by, for example, hot embossing at a temperature of 80°C to 130°C and an embossing pressure of 0.2 MPa to 1.0 MPa.

Figure 4 is an enlarged view of area A in Figure 2. Furthermore, Figure 5 is a cross-sectional view taken along line V-V in Figure 4.

As shown in Figures 4 and 5 , the embossed portion 20 includes an embossed pattern 21 that protrudes upward (on one side of the cleaning paper 100 ) and an embossed pattern 22 that protrudes downward (on the other side of the cleaning paper 100 ) (i.e., is recessed upward).

The embossed patterns 21 and the debossed patterns 22 are arranged in a staggered pattern, alternating in either the X or Y direction. This regular alternation of the embossed patterns 21 and the debossed patterns 22 improves waste collection.

A middle portion 23 is formed between the alternating embossed embossing patterns 21 and debossed embossing patterns 22 in the embossed portion 20. The middle portion 23 is the portion where neither the embossed embossing patterns 21 nor the debossed embossing patterns 22 are formed. Therefore, the middle portion 23 is located lower than the embossed embossing patterns 21 and higher than the debossed embossing patterns 22 in the Z direction.

Furthermore, the embossed pattern described above is not required. Although the effect of improving trash collection is less pronounced, an embossed pattern in which the embossed patterns 21 or the debossed patterns 22 are arranged in a row, or an embossed pattern in which the patterns are arranged irregularly, is also possible. Alternatively, for example, only one of the embossed patterns 21 or the debossed patterns 22 may be provided.

(Embossed)

As shown in Figure 4, the embossed pattern 21 is formed into a gourd-shaped pattern, narrow in the X-direction and with a waist in the center of the Y-direction, when viewed from above. While this shape is preferred from the perspective of waste collection, the embossed pattern 21 is not limited to this. Various shapes, such as circular, elliptical, and polygonal, can be used. Furthermore, a combination of these shapes is also possible.

The embossed knives 21 are formed to have a thickness of 2mm to 5mm, preferably 3mm to 4mm, in the X direction, 5mm to 10mm, preferably 6mm to 8mm, in the Y direction, and 0.5mm to 2mm, preferably 0.7mm to 1.5mm, in the Z direction (height from the center portion 23).

As shown in Figure 5, the embossed pattern 21 is formed in a shape that projects upward in a stepped manner in a cross-sectional view. Specifically, in a cross-sectional view, a second protrusion 21b that further projects upward is formed at the top of a first protrusion 21a that projects from the surface (upper surface) of the dust removal paper.

More specifically, the top of the first protrusion 21a has a flat surface portion H with a diameter of 0.5 mm to 3 mm, preferably 1 mm to 2 mm, at both ends in the Y direction, and has a second protrusion 21b at both ends in the center in the Y direction.

This structure improves the cushioning properties of the dry dust paper 100 for cleaning, and makes it easier to maintain the embossed shape during cleaning.

(Embossed)

As shown in Figure 4, the embossed pattern 22 is formed into a so-called gourd shape, which is substantially the same shape as the embossed pattern 21 when viewed from above. The shape of the embossed pattern 22 is not limited to this and can be formed into various shapes, including a shape different from the embossed pattern 21.

As shown in Figure 5, the embossed pattern 22 is formed to be the inverted version of the embossed pattern 21 in a cross-sectional view, and is recessed in a stepwise manner downward. Specifically, in a cross-sectional view, a second recess 22b, further projecting downward, is formed at the top of a first recess 22a that protrudes from the surface (bottom) of the dust removal paper.

More specifically, the top of the first recess 22a has a flat surface portion H with a diameter of 0.5 mm to 3 mm, preferably 1 mm to 2 mm, at both ends in the Y direction, and has a second recess 22b at both ends in the center in the Y direction.

This structure improves the cushioning properties of the dry dust paper 100 for cleaning, and makes it easier to maintain the embossed shape during cleaning.

(Non-embossing part)

The non-embossed portion 30 is the bristle-bearing portion of the dry cleaning paper 100 that is not compressed in the thickness direction. A plurality of these portions are arranged along the strip-shaped folded portion S of the dry cleaning paper 100.

The non-embossed portion 30 can be formed by designing the embossing roller that will form the embossed portion 20 to exclude the non-embossed portion 30.

Furthermore, the non-embossed portion 30 is not limited to being completely uncompressed. It can also be slightly compressed compared to the uncompressed portion of the embossed portion 20, to the extent that bristles remain. Furthermore, the non-embossed portion 30 also includes portions without bristles.

The size of the non-embossed portion 30 is formed to be 40mm to 70mm in the X direction, preferably 50mm to 60mm, and 15mm to 70mm in the Y direction, preferably 20mm to 50mm.

With this configuration, during manufacturing, when forming the fold line corresponding to the folded portion S on the cleaning dry dust paper 100, even if the fold line meanders due to the device, the fold line can still be formed at the appropriate position.

(concave part)

When the dry dust paper 100 is mounted on the cleaning tool 200, the non-embossed portion 30 preferably has an open recess 31 relative to the long edge 201a of the head 201.

Specifically, as shown in Figure 2 , the non-embossed portion 30 can be formed into a V-shape when viewed from above, extending rightward or leftward, that is, from the center of the rectangular dry dust removal paper 100 toward the long sides. Specifically, a non-embossed portion 30 that is V-shaped when viewed from above will have a V-shaped recess 31.

Thus, when the dry cleaning paper 100 is moved in the Y direction, i.e., in a direction parallel to the short side of the dry cleaning paper 100, for cleaning, it is easier for the dirt to accumulate in the recess 31, further improving the dirt collection efficiency.

Furthermore, as shown in Figure 2, the non-embossed portions 30 are arranged in a staggered manner with their positions offset in the X-direction within each row. Specifically, the non-embossed portions 30 along the fold S corresponding to one side of the long edge 201a of the head 201 and the non-embossed portions 30 along the fold S corresponding to the other side of the long edge 201a of the head 201 are arranged at different positions in the direction in which the fold S extends.

As a result, when the dry dust paper 100 is moved in the Y direction, i.e., parallel to the short side of the dry dust paper 100, the two sheets complement each other's collection capabilities, allowing the non-embossed portion 30 to pass through the floor without gaps, thereby improving the collection of dust.

(Manufacturing method of dry dust paper for cleaning)

Next, the manufacturing method of the dry dust removal paper 100 for cleaning will be described.

The method for manufacturing the dry dust paper 100 for cleaning comprises a lamination step of laminating a plurality of fiber layers, a coating step of coating the laminated dust paper with a CNF solution, a heat drying step of heat-drying the laminated dust paper coated with the CNF solution, and an embossing step of applying pressure to the laminated dust paper using a pair of embossing rollers to emboss the laminated dust paper.

During the lamination step, a water flow interlacing method is used to produce a laminated dust removal paper in which the fibers of the outer layer 11, 11 and the inner layer 12 are interlaced at their boundary areas.

During the coating step, CNF can be produced by known methods, such as dissolving CNF in a solvent to form a CNF dispersion, applying this CNF dispersion to dry cleaning paper 100, and drying it to adhere to the target paper. Furthermore, when applied to fiber dust-removing paper using this method for applying liquid CNF, while some CNF will permeate the paper, the CNF will concentrate on the surface, allowing the CNF to adhere to the outer layer 11. The solvent used to disperse CNF is not particularly limited; however, in addition to water and lower alcohols such as ethanol, volatile organic solvents such as acetone can also be used.

Furthermore, the CNF dispersion can be applied by any conventional coating method, such as transfer printing using a letterpress method, in addition to spraying the surface.

In the heat drying step, any conventional heat drying method can be used, such as a method of drying the nonwoven fabric coated with the CNF solution by placing it in a constant temperature bath, or a method of drying the nonwoven fabric by directly contacting it with the surface of a heated roller such as a Yankee drum.

During the embossing step, for example, heat embossing can be performed at a temperature of 80°C to 130°C and an embossing pressure of 0.2 MPa to 1.0 MPa, thereby forming the embossed portion 20 on the dry dust removal paper 100 for cleaning.

Through this embossing step, the fibers of the inner layer 12 are sandwiched within the fibers of the outer layers 11, 11, and are exposed on or near the surface of the outer layers 11, 11 (dry dust removal paper 100 for cleaning).

Specifically, the fibers of the inner layer 12 are exposed at the edges of the second protrusion 21b or the second recess 22b.

Thus, since the outer layers 11, 11 (cleaning dry dust paper 100) have hydrophilic fibers on or near the surface, liquid dirt can also be easily wiped off.

Furthermore, the non-embossed portion 30 can be formed by designing the embossing roller that will form the embossed portion 20 to exclude the non-embossed portion 30.

(How to use dry dust paper for cleaning)

Next, we'll explain how to use dry dust paper 100 for cleaning.

During use, the dry dust removal paper 100 is mounted on the rectangular, flat head 201 of the cleaning tool 200.

Specifically, the two rows of folded portions S extending in the X direction of the cleaning paper 100 are aligned with the long edge 201a of the head 201, and the head 201 is placed on the cleaning paper 100. Next, the cleaning paper 100 is folded along the long edge 201a of the head 201, so that the two sides of the folded paper engage with the top surface of the head 201.

As shown in Figure 1 , the center portion of the cleaning paper 100 in the Y direction covers the bottom surface of the head 201 of the cleaning tool 200 to form the cleaning surface. Embossed portions 20 and non-embossed portions 30 are alternately arranged along the fold S, corresponding to the long edge 201a of the head 201.

In this state, the dry dust removal paper 100 is primarily moved in the Y direction, or the short-side direction, to clean. The embossed portion 20 scrapes away fine dust such as sand and house dust, while the bristles of the non-embossed portion 30 capture coarse dust such as hair and fiber dust.

More specifically, coarse dust accumulates in the recesses 31 of the non-embossed sections 30, while fine dust is captured by the embossed sections 20 between the non-embossed sections 30 and the embossed sections 20 located on the cleaning surface.

At this time, in the dry dust paper 100 for cleaning, since the fibers in the boundary area between the outer layer 11, 11 and the inner layer 12 are intertwined, the shape of the embossed portion 20 is easily maintained, achieving excellent collection performance.

Furthermore, as the cleaning process progresses, the embossed portion 20 is gradually squeezed together with the second protrusion 21b and the first protrusion 21a (or the second concave portion 22b and the first concave portion 22a), gradually expanding the cleaning area and allowing for extended use.

(Example)

The present invention is described in detail below using examples, but the present invention is not limited to these examples.

[Sample production]

First, an outer layer of PET fibers weighing approximately 50g/ ^m² and containing more than 90% hydrophobic fibers, and an inner layer of PP fibers weighing approximately 15g/ ^m² and containing more than 90% hydrophobic fibers, are laminated using a water jet interlacing method to prepare a three-layered dust removal paper with a size of 10cm×10cm.

Next, pure water or the following coating solutions 1 to 3 with a final concentration of 0.5% were applied to both sides of each nonwoven fabric according to the conditions of Examples 1-14 and Comparative Examples 1-5. The nonwoven fabrics were then placed in a constant temperature bath at 60°C for 24 hours to allow for heat drying.

The laminated dust removal paper was embossed at a temperature of 105°C and an embossing pressure of 0.6 MPa to produce a dry dust removal paper 100 for cleaning having an embossed portion 20 and a non-embossed portion 30 as shown in FIG2 .

(coating fluid)

Coating solution 1: Mix 25g of 2.00% mechanically treated CNF solution in 75g of purified water.

Coating solution 2: Mix 23.8g of 2.10% enzyme-treated CNF solution with 76.2g of purified water.

Coating solution 3: Mix 38.5g of 1.30% TEMPO-oxidized CNF solution with 61.5g of purified water.

In addition, the various "CNF solutions" mentioned above are pure aqueous solutions obtained by mixing pure water and various CNFs.

(Example 1-6)

0.4 g, 0.5 g, 1 g, 2 g, 5 g, and 8 g of coating liquid 1 were applied (CNF coating amount: 0.20 g/m ² , 0.25 g/m ² , 0.50 g/m ² , 1.00 g/m ² , 2.50 g/m ² , and 4.00 g/m ² ).

(Examples 7-10)

0.4 g, 1 g, 5 g, and 8 g of the coating liquid 2 were applied, respectively (CNF coating amount: 0.20 g/m ² , 0.50 g/m ² , 2.50 g/m ² , and 4.00 g/m ² ).

(Examples 11-14)

0.4 g, 1 g, 5 g, and 8 g of the coating liquid 3 were applied, respectively (CNF coating amount: 0.20 g/m ² , 0.50 g/m ² , 2.50 g/m ² , and 4.00 g/m ² ).

(Comparative example 1)

5 g of pure water was applied (CNF application amount: 0.00 g/m ² ).

(Comparative Example 2-3)

0.2 g and 9 g of coating liquid 1 were applied respectively (CNF coating amount: 0.10 g/m ² and 4.50 g/m ² ).

(Comparative example 4)

0.2 g of coating liquid 2 (CNF coating amount: 0.10 g/m ² ) was applied.

(Comparative example 5)

0.2 g of coating liquid 3 was applied (CNF coating amount: 0.1 g/m ² ).

[Evaluation Method]

Place a piece of dry dust paper 100 on a 10 cm x 30 cm acrylic sheet onto which 1.0 g of pure water has been dropped. The sheet is then cleaned twice, back and forth. The weight of the water droplet on the acrylic sheet is measured, and the water absorption of the dry dust paper 100 is calculated as 1.0 minus the weight of the water droplet on the acrylic sheet after cleaning.

This test was conducted three times using 100 sheets of dry dust removal paper from Examples 1-14 and Comparative Examples 1-5, respectively, and the average water absorption was calculated.

The test results are shown in Tables I-III.

[Table 1]

[Table 2]

[Table 3]

[evaluate]

Comparing Comparative Examples 1-3 and Examples 1-6 in Table 1, it can be seen that applying 0.2 g/ ^m² or more of mechanically treated CNF increases the amount of water absorbed by the cleaning dry dust paper 100 compared to applying pure water. This is believed to be due to the water-absorbing properties of CNF, and the increased surface area of the cleaning dry dust paper 100 due to the application of CNF.

Furthermore, when comparing Comparative Example 4 and Examples 7-10, and Comparative Example 5 and Examples 11-14 in Tables II-III, respectively, it can be seen that by applying CNF of any defiberization method at a concentration of 0.2 g/ ^m2 or more, the water absorption of the dry dust removal paper 100 for cleaning can be increased compared to the case of applying pure water.

Furthermore, as the amount of CNF applied increases, the amount of water absorbed by the cleaning dry dust paper 100 also increases. However, a comparison of Example 6 and Comparative Example 3 in Table 1 shows that even with increasing the amount of CNF applied, the amount of water absorbed does not increase much. Therefore, even with an applied CNF amount exceeding 4.0 g/m ² , the amount of water absorbed is difficult to increase.

Furthermore, it was found that when TEMPO-oxidized CNF was applied at a concentration of 0.5 g/ ^m² or more, the amount of water absorbed increased compared to the application of the same amount of mechanically treated CNF or enzyme-treated CNF. This is believed to be because the fiber width (fiber diameter) of TEMPO-oxidized CNF is smaller than that of mechanically treated CNF or enzyme-treated CNF, further increasing the specific surface area of the dry dust removal paper 100 for cleaning.

[Effects of implementation]

As shown above, by applying 0.2 g/ ^m² or more of CNF to the outer layer of the nonwoven fabric, the water absorption of the dry dust paper 100 is improved. Furthermore, increasing the amount of CNF applied increases the water absorption of the dry dust paper 100, making it easier to adjust the water absorption.

However, even if the coating weight exceeds 4.0 g/m ² , the water absorption will not increase much, and the burden of the drying step in the manufacturing process will also increase. Therefore, the coating weight is preferably set to 4.0 g/m ² or less.

Furthermore, since CNF is inexpensive, simply coating the nonwoven fabric with CNF does not significantly increase manufacturing costs. This reduces manufacturing costs while improving the water absorption of the dry dust paper 100 for cleaning.

[Variations]

Although the present invention has been specifically described above based on the embodiments, the present invention is not limited to the above embodiments and can be modified without departing from the spirit and scope of the present invention.

For example, in the above embodiment, although the dry dust paper 100 for cleaning is described as being used for cleaning floors, its use is not limited to this. Furthermore, the components added to the solution can of course be changed depending on the application.

Furthermore, in the above embodiment, the non-embossed portion 30 is provided on the dry dust-removing paper 100 for description. However, the non-embossed portion 30 may not be provided. In other words, the embossed portion 20 may be provided on the entire surface of the dry dust-removing paper 100.

Furthermore, in the above embodiment, although the description is given of a case where the cleaning paper 100 is moved in the Y direction for cleaning, it is also possible to focus on a case where the cleaning paper 100 is moved in a direction parallel to the long side of the cleaning paper 100 for cleaning, and form the non-embossed portion 30 in a shape that opens from the center of the rectangular cleaning paper 100 toward the short side.

At this time, fold the dry cleaning paper 100 along the short edge of the head 201 so that both ends of the folded paper engage with the upper surface of the head 201.

Furthermore, in the above embodiment, although the dry dust paper 100 for cleaning is attached to the cleaning tool 200 for explanation, the dry dust paper 100 for cleaning can also be used directly without being attached to the cleaning tool 200.

Furthermore, the nonwoven fabric of the present invention has no particular limitations on its manufacturing or assembly methods.

For example, the inner layer 12 may not contain PP fibers, which are hydrophobic fibers, but may be composed only of hydrophilic fibers.

Furthermore, the temperature and drying time when using a constant temperature bath for heat drying are also optional.

Although several embodiments of the present invention are described, the scope of the present invention is not limited to the aforementioned embodiments and also includes the scope of the invention described in the patent application and its equivalents.

(Industrial Availability)

The present invention provides a dry dust removal paper for cleaning that can easily adjust its water absorption capacity and has low manufacturing costs.

11: Outer layer (outer fiber layer)

12: Inner layer (inner fiber layer)

100: Clean with dry dust paper

Claims (9)

A dry dust removal paper for cleaning comprises a nonwoven fabric having hydrophobic fibers on its surface, wherein the surface of the nonwoven fabric is coated with cellulose nanofibers having a density of 2.5 g/ ^m2 or more and 4.0 g/ ^m2 or less. A dry dust removal paper for cleaning comprises a nonwoven fabric having hydrophobic fibers on both sides, wherein both sides of the nonwoven fabric are coated with the same amount of cellulose nanofibers at a concentration of 0.2 g/ ^m2 or more and 4.0 g/ ^m2 or less. The dry dust paper for cleaning as claimed in claim 1 or 2, wherein the dry dust paper for cleaning has a multi-layer structure comprising an outer layer forming a surface of the dust paper and inner layers sandwiched between the outer layers, and the inner layer comprises polypropylene fibers. The dry dust removal paper for cleaning as described in claim 1, wherein the outer layer constituting the surface contains more than 80% of polyethylene terephthalate fibers. The dry dust removal paper for cleaning as described in claim 2, wherein the outer layer constituting the double-sided surface contains more than 80% of polyethylene terephthalate fiber. The dry dust removal paper for cleaning as described in claim 1 or 2, wherein the cellulose nanofibers are TEMPO-oxidized cellulose nanofibers. A method for manufacturing dry dust-removing paper for cleaning comprises the following steps: a coating step of coating a cellulose nanofiber solution on a nonwoven fabric so that the coating amount of the cellulose nanofibers is greater than 2.5 g/ ^m2 and less than 4.0 g/ ^m2 ; and a drying step of thermally drying the nonwoven fabric. A method for manufacturing dry dust-removing paper for cleaning comprises the following steps: a coating step of coating the same amount of a cellulose nanofiber solution on both sides of a nonwoven fabric so that the coating amount of the cellulose nanofibers is greater than 0.2 g/ ^m2 and less than 4.0 g/ ^m2 ; and a drying step of thermally drying the nonwoven fabric. The method for producing dry dust-removing paper for cleaning as described in claim 7 or 8, wherein the cellulose nanofibers are TEMPO-oxidized cellulose nanofibers.