JP2021037474A - Cleaning sheet and cleaning method using the same - Google Patents

Abstract

To provide a cleaning sheet excellent in cleaning performance with respect to a card reading device.SOLUTION: A cleaning sheet comprises a first resin layer formed of a foaming body having a first cleaning surface for cleaning an object to be cleaned. The first resin layer has in the foaming body a plurality of foam expanding in a thickness direction, where at least some of foam between the adjacent foam of the plurality of foam are connected foam connected to each other; and comprises on the first cleaning surface an opening formed of some of the plurality of foam that the first resin layer has.SELECTED DRAWING: None

Description

The present invention relates to a cleaning sheet and a cleaning method using the same, and more particularly to a cleaning sheet for cleaning the contact terminals of an IC card reader that performs data communication with a contact type IC card and a cleaning method using the same.

An IC card is an information storage means obtained by molding a semiconductor storage circuit or a control microcomputer into a plate shape, and has a plurality of terminals for connecting to an IC card reader / writer on its surface. Contact-type IC cards are mainly used as cash cards and credit cards in the financial field, and ETC cards in in-vehicle devices for automatic toll collection. In a contact-type IC card, by inserting it into a card reader / writer, power is supplied by contacting both metals, and information in the IC card can be read and written.

Since IC cards are directly carried and used by humans, they are contaminated with oil stains and the like derived from human hand stains (sebum stains) and dust and dirt attached to them. When an IC card is contaminated, the contaminants adhere to various types of card readers via the IC card. Further, for example, in an ETC card reader in an in-vehicle device for automatic toll collection, soot and dust derived from vehicle exhaust gas directly contaminate the ETC card reader. If the card reader is contaminated in this way, the card reader may interfere with signal communication for reading and writing information in the IC card, so it is necessary to clean the card reader. .. When cleaning a card reading device, it is complicated to disassemble and clean the device, so a method of cleaning using a cleaning card is often used.

For example, Patent Document 1 is coated with abrasive particles on one or both sides of a substrate for the purpose of providing a cleaning card that easily and quickly scrapes off contaminants adhering to a card reading unit and wipes and cleans the card. A cleaning card that cleans the reading part of a card reader, which is made by laminating non-woven fabrics, and the size and thickness of the cleaning card are almost the same as the size and thickness of the card used for the card reader. Further, a card for cleaning a reading unit of a card reading device is disclosed, wherein at least a part of the cleaning card becomes opaque.

Jikkenhei 5-73707 Gazette

However, when the card reading device is cleaned using the conventional cleaning card described in Patent Document 1, the non-woven fabric is inferior in adhesion and the degree of surface unevenness is large, so that the adhesion to a contaminated portion in the device is large. However, the wiping property is uneven and the cleaning property is inferior. In addition, since the cleaning property is inferior, when the cleaning operation is repeated, the contaminants once adsorbed on the non-woven fabric may reattach, or the non-woven fabric itself may fall off, resulting in secondary contamination. Further, the abrasive particles contained in the cleaning card may damage the card reading unit and hinder the communication of signals for reading and writing the information in the IC card. In addition, since the cleaning liquid is dropped onto the non-woven fabric in order to improve the cleaning property, when the object to be cleaned is an electronic device, it is necessary to turn off the power at the time of cleaning, which is complicated. Furthermore, since the surface shape of the non-woven fabric is relatively non-uniform, a part of the adsorbed contaminants easily falls off, while the other part of the adsorbed contaminants is strongly adsorbed, so that the non-woven fabric is a non-woven fabric. It is difficult to remove the sebum stains that have soaked into the fibers even if the fibers are washed, and the surface shape is suitable for removing contaminants because the fibers on the surface fall off or fray due to the washing and the fibers are twisted. It is difficult to reuse because it decreases and disappears.

Therefore, an object of the present invention is to provide a cleaning sheet having excellent cleanability for a card reader.

As a result of diligent studies to solve the above-mentioned problems of the prior art, the present inventors have provided a first resin layer made of a foam having a first cleaning surface for cleaning an object to be cleaned, and the first resin layer is provided. , The foam has a plurality of bubbles extending in the thickness direction, and at least a part of the plurality of cells adjacent to each other is connected to each other. The present invention has been completed by finding that the cleaning sheet having an opening formed from a part of a plurality of bubbles of the resin layer is excellent in cleaning property for a card reader.

That is, the present invention is as follows.
[1]
A first resin layer made of a foam having a first cleaning surface for cleaning an object to be cleaned is provided.
The first resin layer is a connecting cell having a plurality of bubbles extending in the thickness direction in the foam, and at least a part of the plurality of cells adjacent to each other is connected to each other.
A cleaning sheet having an opening formed from a part of the plurality of bubbles of the first resin layer on the first cleaning surface.
[2]
The maximum diameter of the connected bubbles parallel to the first cleaning surface of the first resin layer exists inside the first resin layer.
The cleaning sheet according to [1].
[3]
A base material arranged on the side of the first resin layer opposite to the first cleaning surface is further provided.
The cleaning sheet according to [1] or [2].
[4]
The average opening diameter of the openings on the first cleaning surface is 5.0 to 300 μm.
The cleaning sheet according to any one of [1] to [3].
[5]
The opening ratio of the opening on the first cleaning surface is 10 to 60%.
The cleaning sheet according to any one of [1] to [4].
[6]
A second resin layer made of a foam having a second cleaning surface for cleaning the object to be cleaned is provided on the side of the first resin layer opposite to the first cleaning surface.
The second resin layer is a connecting cell having a plurality of bubbles in the foam and at least a part of the plurality of bubbles is connected to each other.
On the second cleaning surface, an opening formed from a part of the connecting bubbles of the second resin layer is formed.
The cleaning sheet according to any one of [1] to [5].
[7]
Further, a base material arranged on one surface side of the first resin layer and one surface side of the second resin layer is further provided.
The base material is arranged on the opposite side of the first resin layer to the first cleaning surface and on the opposite side of the second resin layer to the second cleaning surface.
The cleaning sheet according to [6].
[8]
The maximum diameter of the connected bubbles parallel to the second cleaning surface of the second resin layer exists inside the second resin layer.
The cleaning sheet according to [6] or [7].
[9]
The first resin layer and the second resin layer contain a polyurethane resin.
The cleaning sheet according to any one of [1] to [8].
[10]
A cleaning method comprising a step of cleaning an object to be cleaned using the cleaning sheet according to any one of [1] to [9].
[11]
The cleaning method according to [10], wherein the object to be cleaned includes a reading unit that reads card information by contact with the object to be cleaned.

The cleaning sheet according to the present invention is excellent in cleanability for a card reader.

It is a partial cross-sectional view schematically showing an example of the case where a part of the cleaning sheet of this embodiment has the maximum diameter of the connected air bubbles inside the cleaning surface. It is a partial cross-sectional view schematically showing an example of the case where the bubble diameter of the connecting bubble becomes smaller from the cleaning surface toward the opposite surface with respect to a part of the cleaning sheet of this embodiment. A partial cross section schematically showing an example of a part of the cleaning sheet of the present embodiment in which the cleaning sheet includes a first resin layer, a first adhesive layer, a base material, a second adhesive layer, and a second resin layer in this order. It is a figure. 3 is a graph showing the measurement results of the cleaning sheet pieces of Examples 1 to 3 and Comparative Examples 1 and 2 with the deformation amount (mm) on the horizontal axis and the pressure (g / cm ^{2) on the vertical axis.} It is a photograph which observed the cross section of the cleaning sheet of Example 1 at 50 times using an electron microscope. It is a photograph which observed the cross section of the cleaning sheet resin layer of Example 1 at 500 times using an electron microscope. It is a photograph which observed the cleaning surface of the cleaning sheet of Example 1 at 50 times using an electron microscope. It is a photograph of the cross section of the cleaning sheet of Comparative Example 1 observed at 50 times using an electron microscope. It is a photograph which observed the cross section of the cleaning sheet of Comparative Example 1 at 500 times using an electron microscope. It is a photograph which observed the cleaning surface of the cleaning sheet of Comparative Example 1 at 50 times using an electron microscope.

Hereinafter, embodiments for carrying out the present invention (hereinafter, simply referred to as “the present embodiment”) will be described in detail with reference to the drawings as necessary, but the present invention is limited to the following embodiments. It's not a thing. The present invention can be modified in various ways without departing from the gist thereof. In the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. In addition, the positional relationship such as up, down, left, and right shall be based on the positional relationship shown in the drawings unless otherwise specified. Furthermore, the dimensional ratios in the drawings are not limited to the ratios shown.

The cleaning sheet of the present embodiment includes a first resin layer made of a foam having a first cleaning surface for cleaning an object to be cleaned. Such a cleaning sheet can be produced, for example, by attaching a base material to the side opposite to the cleaning surface of the resin layer with an adhesive layer (hereinafter, also referred to as "adhesive layer").
Further, the first resin layer is a connecting bubble having a plurality of bubbles in the foam and at least a part of the plurality of bubbles is connected to each other. Further, on the first cleaning surface, an opening formed from a part of the connecting bubbles is formed.

The reason why such a cleaning sheet is excellent in cleanability for a card reader is considered as follows. However, the factors are not limited to this. When a card reading device is cleaned using a conventional cleaning card made of non-woven fabric, the non-woven fabric does not have sufficient followability to the shape inside the device, is inferior in adhesion to contaminants, and is inferior in cleaning property. In addition, since the cleaning property is inferior, if the cleaning operation is repeated repeatedly, the contaminants once adsorbed by the non-woven fabric may be reattached, or the non-woven fabric itself may fall off, resulting in secondary contamination. Further, when the cleaning card contains abrasive particles, the card reading unit may be damaged, which may hinder the communication of signals for reading and writing information in the IC card. In addition, since the cleaning liquid is dropped onto the non-woven fabric in order to improve the cleaning property, when the object to be cleaned is an electronic device, it is necessary to turn off the power at the time of cleaning, which is complicated. Furthermore, since the surface shape of the non-woven fabric is relatively non-uniform, a part of the adsorbed contaminants easily falls off, while the other part of the adsorbed contaminants is strongly adsorbed, so that the non-woven fabric is a non-woven fabric. It is difficult to reuse it even if it is washed. On the other hand, the cleaning sheet of the present embodiment has a first cleaning surface made of a resin material by providing a plurality of air bubbles extending in the thickness direction in a foam having a first cleaning surface for cleaning an object to be cleaned. Is easy to follow the shape of the object to be cleaned, and as a result of adhering to the contaminated part in the device, it is excellent in cleanability. Further, in the cleaning sheet of the present embodiment, the amount of compression deformation on the first cleaning surface side made of a resin material made of foam can be relatively large due to a plurality of bubbles in the foam, so that the object to be cleaned The shape of the is easy to follow, and it is possible to remove contaminants of various sizes.
Further, the cleaning sheet of the present embodiment does not need to use a cleaning liquid as in the case of using a conventional non-woven fabric.
In addition, the cleaning sheet of the present embodiment has openings formed from a part of a plurality of bubbles of the first resin layer on the first cleaning surface, so that contaminants removed from the object to be cleaned Can be held inside the connected air bubbles through the opening, so that the contaminants once removed can intervene between the connected air bubbles and are difficult to fall off.
As described above, the cleaning sheet of the present embodiment is excellent in cleaning property for the card reading device. Further, by arranging the maximum diameter of the bubble diameter parallel to the first cleaning surface of the connected bubble of the first resin layer so as to exist inside the first resin layer, the contaminants once taken into the bubble can be removed. It can be suppressed from being released again.

FIG. 1 is a partial cross-sectional view schematically showing an example of a part of the cleaning sheet of the present embodiment in which the diameter of the connected bubbles has the maximum diameter inside the cleaning surface. The cleaning sheet 1A includes a polyurethane resin layer 2 (hereinafter, simply referred to as “resin layer 2”). The resin layer 2 has a cleaning surface P for cleaning the object to be cleaned. The cleaning surface P is a resin layer described later so that the bubbles of the foam are exposed to form an opening and the thickness of the resin layer 2 (the length in the vertical direction of FIG. 1) is substantially uniform. The surface (upper surface) in the step of preparing 2 is buffed or sliced to be flattened. On the other hand, the back side of the cleaning surface P is not buffed or sliced. However, buffing or slicing may be applied. Further, the cleaning sheet 1A is provided via an adhesive 7 in which the back surface side (the surface side not buffed) of the cleaning surface P and one side of the base material 8 are an adhesive layer, or an adhesive 7 which is an adhesive layer. It is pasted together.

FIG. 2 is a partial cross-sectional view schematically showing an example of a part of the cleaning sheet of the present embodiment in which the diameter of the connected bubbles decreases from the cleaning surface toward the opposite surface. The cleaning sheet 1B includes a resin layer 2 having a cleaning surface P for cleaning the object to be cleaned, as in the configuration of FIG. However, the back surface (lower surface) in the step of preparing the resin layer 2 described later is buffed or sliced, and that surface is designated as the cleaning surface P. Further, the cleaning sheet 1B is provided via an adhesive 7 in which the back surface side (the surface side not buffed) of the cleaning surface P and one side of the base material 8 are an adhesive layer, or an adhesive 7 which is an adhesive layer. It is pasted together.

FIG. 3 schematically shows an example of a part of the cleaning sheet of the present embodiment in which the cleaning sheet is provided in the order of the first resin layer, the first adhesive layer, the base material, the second adhesive layer, and the second resin layer. It is a partial cross-sectional view shown. The cleaning sheet 1C (hereinafter, the cleaning sheets 1A, 1B, and 1C are collectively referred to as "cleaning sheet 1") has a cleaning surface P1 for cleaning the object to be cleaned, as in the configuration of FIG. It includes a resin layer 2a, an adhesive 7a which is a first adhesive layer, and a base material 8a (not distinguished from the base material 8 in FIG. 3).
The cleaning sheet 1C has a second surface similar to the first resin layer 2a and the first adhesive layer 7a on the side opposite to the surface where the base material 8a is bonded to the resin layer 2a via the adhesive 7a. The resin layer 2b (hereinafter, the first resin layer 2a and the second resin layer 2b are collectively referred to as "resin layer 2") and the adhesive 7b which is the second adhesive layer (hereinafter, the adhesives 7a and 7b are collectively referred to as "resin layer 2"). Also referred to as "adhesive 7"). Here, the base material 8b (not distinguished from the base material 8 in FIG. 3) is bonded to the resin layer 2b via the adhesive 7b. Further, the resin layer 2b includes a cleaning surface P2 (hereinafter, the cleaning surfaces P1 and P2 are collectively referred to as a "cleaning surface P") like the resin layer 2a.
In FIG. 3, the base material 8 shows the base material 8a and the base material 8b as the same base material for convenience, but the base material 8a and the base material 8b may be the same, and different base materials are used. There may be. When they are separate substrates, they may be adhered to each other with an adhesive or double-sided tape. When adhering with a double-sided tape, the double-sided tape may be a non-support type having no base material or having an adhesive arranged on both sides of the base material.

Hereinafter, the cleaning sheets shown in FIGS. 1 to 3 will be described in a comprehensive manner unless otherwise specified.

The resin layer 2 is made of a foam of resin constituting the layer, and pot-shaped bubbles 3 having a rounded bottom are formed along the thickness direction thereof. In the resin portion between the bubbles 3 of the resin layer 2, microbubbles smaller in size than the bubbles 3 (not shown) are formed. The microbubbles existing in the resin portion forming the bubble 3 are connected cells in which the bubbles are connected to each other in a three-dimensional network. The connected bubbles indicate both a case where the bubbles 3 are connected to each other without the resin wall and a case where the bubbles 3 are connected by the minute bubbles existing on the resin wall. Since the resin layer 2 has connecting bubbles, the minute foreign matter taken in from the opening of the cleaning surface P can be stored in a state where it can intervene in the three-dimensional mesh-like connecting bubbles, and the fine foreign matter once taken in is released to the outside. It is difficult to make it. However, most of the bubbles contained in the resin layer 2 are connected cells, but some of them may be independent cells. Since the cleaning surface P is a surface exposed by buffing or the like, openings for air bubbles 3 are formed in the cleaning surface P. In addition, in FIGS. 1 and 3, the resin layer 2 before being buffed or sliced has a skin layer on which fine microporous is formed on the cleaning surface P side. However, the resin layer 2 in FIG. 2 does not have a skin layer on the cleaning surface P side.

The thickness of the resin layer 2 is not particularly limited, but may be, for example, 100 to 1500 μm or 200 to 500 μm. The thickness of the resin layer 2 is measured according to the measuring method described in JIS K6550: 1994. That is, it is the thickness when a load of 100 g per ^{1 cm 2} is applied (loaded) as the initial load in the thickness direction of the resin layer 2.

In the resin layer 2 of the present embodiment, the average opening diameter of the openings leading to the cleaning surface P is preferably 5.0 to 300 μm, more preferably 10 to 150 μm. When the average opening diameter is 5.0 μm or more, the cleaning property is excellent due to the enhancement of the ability to collect pollutants. Further, since the average opening diameter is 300 μm or less, the adhesion of the cleaning surface P can be maintained, so that the cleaning property is excellent.

The aperture ratio of the opening is preferably 10 to 60%. When the aperture ratio is 10% or more, the cleaning property is improved due to the enhancement of the ability to collect pollutants. Since the opening ratio of the opening is 60% or less, the adhesion of the cleaning surface P can be maintained, so that the cleaning property is excellent.

The average opening diameter and aperture ratio of the resin layer 2 are measured as follows. That is, first, a rectangular region of 1.0 mm × 1.4 mm arbitrarily selected on the cleaning surface P of the resin layer 2 is magnified 175 times with a microscope (trade name “VH-6300” manufactured by KEYENCE). Observe and obtain the image. Next, the obtained image is binarized by image analysis software (for example, (Image Analyzer V20LAB Ver.1.3)) to distinguish between the opening and the other portion. Then, the diameter equivalent to a circle, that is, the opening diameter is calculated on the assumption that the opening is a perfect circle from the area of each of the distinguished openings. Then, the opening diameters of the respective openings are arithmetically averaged to obtain an average opening diameter (μm). Further, the area of the opening with respect to the total area of the opening and the other resin portion is defined as the aperture ratio (%).

The resin layer 2 has a plurality of bubbles 3 in a material (hereinafter, referred to as “matrix material”) constituting a matrix such as a resin, and is formed by a so-called wet film forming method. However, the resin layer in the cleaning sheet of the present invention may be formed by a dry molding method or another molding method as long as openings due to air bubbles are formed on the cleaning surface P.

The matrix material constituting the resin layer 2 has, for example, a composition containing the largest amount of polyurethane resin, and here, the resin layer 2 contains 80 to 100% by mass of polyurethane resin with respect to the total amount of the matrix material. There may be. The resin layer 2 contains the polyurethane resin in an amount of 85 to 100% by mass, more preferably 90 to 100% by mass, and particularly preferably 90 to 95% by mass, based on the total amount thereof.

Examples of the polyurethane resin include polyester-based polyurethane resin, polyether-based polyurethane resin, and polycarbonate-based polyurethane resin, and these are used alone or in combination of two or more. Among these, a polyester-based polyurethane resin is preferable from the viewpoint of more effectively and surely fulfilling the object of the present invention.

The polyurethane resin may be synthesized by a conventional method, or a commercially available product may be obtained. Examples of commercially available products include Chrisbon (trade name manufactured by DIC Corporation), Samplen (trade name manufactured by Sanyo Chemical Industries, Ltd.), and Resamine (trade name manufactured by Dainippon Fine Chemical Industries, Ltd.). Be done. One type of polyurethane resin may be used alone, or two or more types may be used in combination.

The resin layer 2 may contain other resins such as polysulfone resin and / or polyimide resin in addition to the polyurethane resin. The polysulfone resin may be synthesized by a conventional method, or a commercially available product may be obtained. Examples of commercially available products include Udel (trade name manufactured by Solvay Advanced Polymers Co., Ltd.). The polyimide resin may be synthesized by a conventional method, or a commercially available product may be obtained. Examples of commercially available products include Aurum (trade name manufactured by Mitsui Chemicals, Inc.).

In addition to the resin, the resin layer 2 is a material usually used for the resin layer, for example, a pigment such as carbon black, a hydrophilic additive such as sodium lauryl sulfate, and polypropylene glycol, as long as it does not hinder the solution of the problem of the present invention. It may contain one or more of hydrophobic additives and water repellents such as. Further, various materials such as a solvent used in the manufacturing process of the resin layer 2 may remain in the resin layer 2 as long as they do not hinder the solution of the problem of the present invention.

The content of the pigment in the resin layer 2 is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 1.0% by mass or more, based on 100% by mass of the total solid content constituting the resin layer 2. It is 15% by mass or less. When the pigment content is within the above range, the bubbles in the resin layer 2 can be easily arranged in a vertically long shape, the adhesion of the cleaning surface can be further improved, and the rigidity of the resin layer 2 can be improved, so that the cleaning property can be improved. And there is a tendency to improve durability.

The content of the hydrophobic additive in the resin layer 2 is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.1% by mass, based on 100% by mass of the total solid content constituting the resin layer 2. It is by mass% or more and 10% by mass or less, and more preferably 1.0% by mass or more and 5.0% by mass or less. When the content of the hydrophobic additive is within the above range, it is possible to promote the formation of air bubbles inside the resin layer and stabilize the solidification and regeneration of the polyurethane resin, which tends to contribute to the stabilization of the physical properties of the cleaning sheet. It is in.

The content of the hydrophilic additive in the resin layer 2 is preferably 0.01% by mass or more and 20% by mass or less, more preferably 0.1% by mass, based on 100% by mass of the total solid content constituting the resin layer 2. It is by mass% or more and 10% by mass or less, and more preferably 0.5% by mass or more and 3.0% by mass or less. When the content of the hydrophilic additive is within the above range, it is possible to promote the formation of air bubbles inside the resin layer and stabilize the solidification and regeneration of the polyurethane resin, which tends to contribute to the stabilization of the physical properties of the cleaning sheet. It is in.

The cleaning surface P of the resin layer 2 may have fine pores having a bubble diameter of 10 μm or less that does not extend in the thickness direction, which is distinguished from the openings derived from the bubbles 3. The size of the fine pores can be adjusted by adding an additive at the time of blending the resin forming the resin layer 2, for example.

The adhesive 7 may contain a double-sided tape or an adhesive usually used for joining a resin layer or a plastic material. The adhesive or double-sided tape used at this time is not particularly limited, and can be arbitrarily selected from the adhesives and double-sided tapes known in the art.

The base material 8 is for supporting the resin layer 2, and is not particularly limited, and may be a base material usually used for supporting the resin layer or a plastic material, and is made of polyethylene terephthalate (hereinafter, “PET”). A resin film such as a film can be mentioned.

The thickness of the cleaning sheet is preferably 300 to 1000 μm, more preferably 400 to 900 μm. Since the thickness is within the above range, the adhesion to the inside of equipment such as automatic ticket gates, ATMs, vending machines, and various card reader / writers is improved, and cleaning can be performed more effectively.

Preferably the density of the cleaning sheet is 0.5 to 1.5 g / cm ^3, more preferably from 0.6 to 1.2 g / cm ^3, is 0.7~1.0g / cm ³ Is even more preferable. When the density is within the above range, the rigidity is maintained, so that the product can be used repeatedly.

The compressibility of the cleaning sheet is preferably 3 to 20%, more preferably 5 to 18%, and even more preferably 6 to 17%. When the compression ratio is within the above range, it can be compressed and deformed so as to follow the shape of the cleaning surface, and the adhesion to the cleaning surface is improved, so that the cleaning property can be improved.

The compressive elastic modulus of the cleaning sheet is preferably 80 to 100%, more preferably 85 to 99%, and even more preferably 90 to 98%. When the compressive elastic modulus is within the above range, the stress of the compressed and adhered cleaning sheet pushing back the cleaning surface increases, so that the cleaning property can be improved.

The shore A hardness of the cleaning sheet is preferably 50 to 95 °, more preferably 60 to 90 °, and even more preferably 70 to 85 °. When the shore A hardness is within the above range, the cleaning surface has compressibility and compressibility and is flexible, but the hardness of the entire sheet is high, so that the cleaning surface has appropriate rigidity, and the inside of the cleaning device is complicated. It is possible to follow a simple transport path without bending, and it is possible to have durability that allows it to be washed and used repeatedly after use.

Regarding the fact that after using the cleaning sheet, it can be reused by cleaning. With the conventional cleaning sheet made of non-woven fabric, when cleaning, the fibers on the cleaning surface may fall off or fray, and the fibers may be biased to remove dust and dirt. The unevenness is reduced or disappeared. On the other hand, in the cleaning sheet of the present application, the bubble structure does not collapse even after cleaning, and the slight adhesiveness of the resin surface is derived from the properties of the resin. Therefore, the slight adhesiveness is not lost even after cleaning and drying. It can be reused by cleaning and removing dust and dirt adhering to the surface and drying it.

Next, an example of the method for manufacturing the cleaning sheet of the present embodiment will be described. Here, the case where the resin layer 2 is produced by the wet film forming method will be described, but the method for producing the resin layer in the cleaning sheet of the present invention is not limited to this. This manufacturing method includes a step of preparing the resin layer 2 and a step of adhering the base material 8 to the resin layer 2 using the adhesive 7 to obtain the cleaning sheet 1.

The step of preparing the resin layer 2 further prepares a resin solution containing a resin, a solvent, and if necessary, a pigment, a hydrophilic additive, and a hydrophobic additive, using a stirring device equipped with a stirring blade. It has a step (resin solution preparation step) and a step of molding the resin layer 2 from the resin solution (molding step).

The steps of molding the resin layer 2 are further a step of applying a resin solution to the surface of a film-forming base material (coating step) and a step of solidifying and regenerating the resin in the resin solution to form a precursor sheet. (Coagulation / regeneration step), a step of washing / drying the precursor sheet to obtain the resin layer 2 (washing / drying step), and a step of grinding and / or partially removing the resin layer 2 by buffing or slicing (slicing / drying). It has a grinding / removing process). Hereinafter, each step will be described.

First, in the resin solution preparation step, a resin such as the above-mentioned polyurethane resin, a solvent that can dissolve the resin and is miscible with the coagulation liquid described later, and if necessary, a pigment and hydrophilicity that can be contained in the resin layer 2. A resin solution is prepared by mixing a sex additive, a hydrophobic additive and other materials (for example, a pore forming agent, a water repellent, etc.) and, if necessary, defoaming under reduced pressure. The solvent is not particularly limited, and examples thereof include N, N-dimethylformamide (hereinafter referred to as “DMF”) and N, N-dimethylacetamide. The content of the resin with respect to the total amount of the resin solution is not particularly limited, but may be, for example, in the range of 10 to 50% by mass or in the range of 15 to 35% by mass.

Next, in the coating step, the resin solution is applied to the surface of the strip-shaped film-forming substrate using a coating device such as a knife coater, preferably at room temperature, to form a coating film. The thickness of the resin solution to be applied at this time may be appropriately adjusted so that the thickness of the finally obtained resin layer 2 becomes a desired thickness. Examples of the material of the film-forming base material include resin films such as PET films, fabrics, and non-woven fabrics. Among these, a resin film such as a PET film, which can increase the rigidity of the entire cleaning sheet even if the thickness is thin, is preferable.

Next, in the solidification / regeneration step, the coating film of the resin solution applied to the film-forming substrate is continuously guided into the coagulation liquid containing a poor solvent for the resin (for example, water in the case of polyurethane resin) as a main component. .. An organic solvent such as a polar solvent such as a solvent in the resin solution may be added to the coagulating liquid in order to adjust the regeneration rate of the resin. The temperature of the coagulating liquid is not particularly limited as long as it can coagulate the resin, and may be, for example, 15 to 65 ° C. In the coagulating liquid, first, a film (skin layer) is formed at the interface between the coating film of the resin solution and the coagulating liquid, and innumerable fine microporouss are formed in the resin in the immediate vicinity of the film. After that, the regeneration of the resin having an open cell structure preferably proceeds due to the coordinated phenomenon of the diffusion of the solvent contained in the resin solution into the coagulating solution and the infiltration of the poor solvent into the resin. At this time, if the film-forming base material is difficult for the liquid to permeate (for example, PET film), the coagulating liquid does not permeate the base material, so that the solvent in the resin solution and the poor solvent are replaced near the skin layer. It occurs preferentially in, and tends to form larger pores in the area inside the skin layer than in the vicinity of the skin layer. In this way, a precursor sheet is formed on the film-forming substrate.

Next, the precursor sheet obtained by the solidification / regeneration step is peeled from the film-forming substrate, and then washed and dried. In the washing / drying step, the solvent remaining in the precursor sheet formed by the washing treatment is removed to obtain the resin layer 2. Water can be used as the cleaning liquid used for cleaning. The resin layer 2 after washing is dried. The resin layer 2 may be dried by a conventional method, for example, it may be dried at 80 to 150 ° C. for about 5 to 60 minutes in a dryer. The resin layer 2 that has undergone the above steps may be wound into a roll.

Next, in the grinding / removing step, the front surface (upper surface) and / or the back surface (lower surface) in the step of preparing the resin layer 2 is ground and / or partially removed by buffing or slicing. By buffing or slicing, the thickness uniformity of the resin layer can be improved, and the connected bubbles are exposed on the cleaning surface to form openings, so that contaminants from the object to be cleaned are retained in the bubbles. be able to.

Next, the base material 8 is attached to the opposite surface of the resin layer 2 to the cleaning surface via the adhesive 7 to obtain the cleaning sheet 1. In this way, the adhesive 7 and the base material 8 which are the adhesive layers are laminated in this order on one surface of the resin layer 2, and the cleaning sheet 1A or 1B is obtained. Further, the cleaning sheet 1C can be obtained by joining the base material surfaces of the cleaning sheets 1A or 1B to each other via the double-sided tape.

When the resin layers 2 are arranged on both surfaces, the opening of the cleaning surface is not limited to a small one, and the cleaning surface may be bonded in the direction of bubbles having a large opening diameter to increase the opening of the cleaning surface. It may be bonded so that the opening of the cleaning surface on the side is small and the opening of the cleaning surface on the other surface is large.

The object to be cleaned with the cleaning sheet 1 includes an insertion port into which the sheet-like substance is inserted and an arrangement portion for arranging the sheet-like substance inside the insertion port, and the cleaning sheet 1 is inserted. It is not particularly limited as long as it can be inserted through the mouth to clean the portion of the arrangement portion that comes into contact with the cleaning sheet 1. Specific examples thereof include electronic terminal devices provided with an insertion slot for loading and unloading cards. In such an electronic terminal device, a plurality of transport roller pairs for loading and unloading the card inserted from the insertion slot are provided in the transport path. The card inserted from the insertion slot is transported in the transport path by a pair of transport rollers, is placed at a predetermined position (placement unit), and can read and write information in the card by contacting or not contacting the card reading unit. it can. In the case of such an electronic terminal device, the cleaning sheet 1 is inserted and transported in the same manner as the card inserted from the insertion slot, so that the cleaning sheet 1 comes into contact with the card and becomes dirty, or dust mixed from the insertion slot. Clean it by contacting it with a member (conveyor roller pair, card reader) that gets dirty due to such things.

The cleaning method of the present embodiment includes a step of cleaning the object to be cleaned using the cleaning sheet described above.

Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these Examples.

(Example 1)
For 100 parts by mass of a solution in which 30% by mass of polyester polyurethane resin, which is a raw material resin to be a matrix resin, is dissolved in DMF (N, N-dimethylformamide), 60 parts by mass of DMF for viscosity adjustment and carbon black pigment (Mitsubishi) A resin solution was prepared by mixing and stirring 16 parts by mass of a DMF dispersion containing 12% by mass of the trade name "RCF44" manufactured by Kagaku Co., Ltd.

Next, a commercially available PET film was prepared as a substrate for film formation, the prepared resin solution was applied thereto, and the clearance of the coating device was adjusted to obtain a coating film having a thickness of 350 μm. Next, the obtained coating film was immersed in a coagulation bath composed of water as a coagulation liquid together with a film-forming base material, and the resin was coagulated and regenerated to obtain a precursor resin layer. The precursor resin layer is taken out from the coagulation bath, the substrate for film formation is peeled off from the precursor resin layer, and then the precursor resin layer is washed with a cleaning solution (desolvent bath) at room temperature composed of water and dried. I rolled it up. Next, the thickness with respect to the surface of the resin layer (the surface opposite to the surface on the side where the film-forming substrate was peeled off and opposite to the surface in contact with the film-forming substrate). It was buffed for 150 μm to a thickness of 200 μm, and an opening was formed on the surface after the buffing.

Prepare two sheets in which the back surface of the obtained resin layer (the surface opposite to the buffed surface) and a commercially available PET base material having a thickness of 0.188 mm are bonded with an adhesive, and use a commercially available double-sided tape. , The surfaces on which the PET base material is exposed were bonded to each other to obtain a cleaning sheet in which a resin layer, an adhesive, a PET base material, a double-sided tape, a PET base material, an adhesive, and a resin layer were laminated in this order. Then, it was punched to a size of JIS type II size (53.9 mm × 85.6 mm) to prepare a card-shaped cleaning sheet having a thickness of 0.89 mm.

(Example 2)
A cleaning sheet having a thickness of 0.79 mm was prepared in the same manner as in Example 1 except that the exposed surfaces of the two resin layers with PET base materials were bonded to each other with an acrylic adhesive. Made.

(Example 3)
A cleaning sheet was obtained in the same manner as in Example 1 except that the clearance was adjusted to change the thickness of the coating film from 350 μm to 550 μm and the buffing treatment for the thickness of 150 μm was changed to the buffing treatment for the thickness of 350 μm. It was.

(Comparative Example 1)
A 0.79 mm thick "S85PG" manufactured by Chikami Miltec Co., Ltd., in which a non-woven fabric made of acrylic synthetic fiber was adhered to both sides of a polyethylene terephthalate base material, was used.

(Comparative Example 2)
"C91" manufactured by Chikami Miltec Co., Ltd. having a thickness of 0.93 mm in which a non-woven fabric made of an acrylic synthetic fiber was adhered to both sides of an olefin fiber base material was used.

The physical characteristics of the cleaning sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were measured by the following methods, respectively.

(Average aperture diameter, aperture ratio)
The opening on the cleaning surface was measured as follows. A range of 1.0 × 1.4 mm square was magnified 175 times and observed with a microscope (trade name “VH-6300” manufactured by KEYENCE), and the obtained image was observed with image processing software (Image Analyzer V20LAB Ver. It was processed and calculated according to 1.3). The results are shown in Table 1 below.

(Compressibility and compressive elastic modulus)
The compressibility and compressive elastic modulus were determined in accordance with Japanese Industrial Standard JIS L 1021. Specifically, the thickness t0 after applying the initial load for 30 seconds from the unloaded state at room temperature is measured, and then the thickness t1 after applying the final load for 5 minutes from the state of the thickness t0 is measured. did. Next, all the loads were removed from the state of the thickness t1, left for 5 minutes (in the no-load state), and then the initial load was applied again for 30 seconds, and then the thickness t0'was measured.
The compressibility is calculated by the formula: compressibility (%) = 100 × (t0-t1) / t0, and the compressibility is compressibility (%) = 100 × (t0'-t1) / (t0-t1). ) Was calculated. At this time, the initial load was 100 g / cm 2 and the final pressure was 1120 g / cm ² .

(Shore A hardness)
For shore A hardness, a cleaning sheet sample piece (10 cm x 10 cm) is cut out, and a plurality of the sample pieces are stacked so as to have a thickness of 4.5 mm or more, and put on an A type hardness tester (Japanese Industrial Standards, JIS K7311). Was measured.

(Thickness variation)
For the thickness variation of the cleaning sheet, measure the thickness of 4 places at equal intervals in the horizontal direction and 3 places at equal intervals in the vertical direction in the surface of the cleaning sheet, and measure the thickness at 12 places in total, and calculate the standard deviation σ of the thickness at 12 places. , The coefficient of variation of the thickness was obtained by dividing by the average value of the thickness. The coefficient of variation of the thickness indicates the variation in thickness, and the smaller the value, the smaller the variation in thickness and the higher the adhesion.

(Compressive stress)
A piece of cleaning sheet is cut into 25 mm x 25 mm, and a circular pressure plate with a temperature of 25 ° C., a compression rate of 0.1 mm / min, and a diameter of 10 mm is used using a micro autograph (manufactured by Shimadzu Corporation, "MST-1"). (Indenter), the amount of compression and the load were measured. FIG. 4 is a graph showing the measurement results of the cleaning sheet pieces of Examples 1 to 3 and Comparative Examples 1 and 2 with the deformation amount (mm) on the horizontal axis and the pressure (g / cm ^{2) on the vertical axis.} is there. In Table 1 below, each stress at the time of 20 μm and 50 μm deformation is shown. As a result of Examples 1 to 3, the stress-strain curves overlapped and showed almost the same amount of deformation.

The cross section and cleaning surface of the cleaning sheets of Example 1 and Comparative Example 1 were observed with an electron microscope (trade name "JMS-5500LV" manufactured by JEOL Ltd.). 5 and 6 are photographs of the cross section of the cleaning sheet of Example 1 observed at 50 and 500 times using an electron microscope, respectively. Further, FIG. 7 is a photograph of the cleaning surface of the cleaning sheet of Example 1 observed at a magnification of 50 using an electron microscope. Similarly, FIGS. 8 and 9 are photographs of the cross sections of the cleaning sheet of Comparative Example 1 observed at 50 and 500 times using an electron microscope, respectively. Further, FIG. 10 is a photograph of the cleaning surface of the cleaning sheet of Comparative Example 1 observed at a magnification of 50 using an electron microscope. From the cross-sectional photographs (50 times, 500 times) of Example 1, it can be seen that bubbles are formed in the direction from the cleaning surface to the PET base material surface. Further, it can be seen that the black dots inside the bubbles in the photograph magnified 500 times indicate the communication holes, and the resin portion is slightly foamed. On the other hand, from the cross-sectional photograph of the comparative example, it can be seen that the fibers are densely laminated, and no voids extending inward from the cleaning surface can be seen. Here, as can be seen with reference to FIG. 6, in the cleaning sheet of Example 1, the maximum diameter of the bubble diameter parallel to the cleaning surface is not on the cleaning surface but exists inside the resin layer. By having such a structure, it is presumed that the cleaning sheet can take in a lot of minute foreign substances inside the bubbles and it is difficult to release the once taken-in fine foreign substances to the outside.
In the photograph of the cleaning surface of Example 1, a substantially circular black portion indicates an opening. Comparing the photographs of the cleaning surface, it can be seen that the cleaning surface of the example has uniform openings as compared with the cleaning surface of the comparative example in which the voids are non-uniform.

Using the cleaning sheets obtained in Examples 1 to 3 and Comparative Examples 1 and 2, the cleanability was evaluated under the following conditions.

As described below, test contaminants 1 to 4 were prepared using the prepared powders 1 to 3, artificial sebum and cotton dust.
Powder 1: JIS Z8901 test powder 3 types (glass sand: SiO ₂ 95% or more, particle size 9 to 61 μm, high hardness, reference material for dust with angular particle shape)
Powder 2: JIS Z8901 test powder 15 types (mixed powder 8 types 72%, 12 types 23%, cotton linter 5% mixture, so-called indoor dust containing cotton dust from clothing, etc. Assumed and standardized substance)
Powder 3: JIS Z8901 test powder 12 types (carbon black, particle size 0.03 to 0.2 μm, standardized substance assuming soot-like substance)
Artificial sebum: A mixture of 70% by mass of oleic acid and 30% by mass of palmitic acid Cotton dust: Cotton linter (1.5 μmx in diameter x 1 mm or less in length)
Test contaminant 1: Powder 1
Test contaminant 2: Mixture of test powder 1 and artificial sebum at mass standard 1:10 Test contaminant 3: Mixture of test powder 2 and artificial sebum at mass standard 1:10 Test contaminant 4: Mixture of test powder 3 and artificial sebum according to mass standard 1:10 Test contaminant 5: Artificial sebum

After adhering each test contaminant prepared to the IC chip reader in the card processing device to the extent that the reading of the card processing device causes an error, the cleaning sheet is taken in and out 5 times to perform the cleaning operation. went. After that, the dirt adhering to the cleaning sheet was visually confirmed, and the operation was confirmed whether or not the reading error of the card processing device was resolved. If it can be confirmed that a lot of dirt is attached to the cleaning sheet and the reading error of the card processing device is resolved ◎, it can be confirmed that the cleaning sheet is dirty and the card processing device is read. The case where the error of (1) was resolved was evaluated as ◯, and the case where the cleaning sheet was not dirty and the error of reading the card processing device was not resolved was evaluated as "x".

Comparative Examples 1 and 2 in which the cleaning surface is a non-woven fabric can be wiped off if only powder or artificial sebum is used, but can exhibit cleaning property against hard-to-remove stains in which powder and artificial sebum are mixed. There wasn't. On the other hand, the example product has a small thickness variation and has the same hardness as the comparative example product, but has a small stress due to deformation and is easily deformed. That is, in the example product, the stress when deformed by 20 μm is 44 g / cm ² , whereas in the comparative example product, the stress is 100 g / cm ² and 124 g / cm ² , and in the example product, the stress is deformed by 50 μm. It was to stress that is 204 g / cm ² when, in the stress of comparison example is ^{408g / cm 2, 811g / cm} 2. That is, when foreign matter of 20 μm or 50 μm size is present, the comparative example product cannot be compressed and deformed to the extent that the foreign matter can be taken in unless a force larger than that of the example product is applied to the cleaning sheet. Since the cleaning sheet can be compressed and deformed with a relatively small force, the adhesion to the cleaning surface and the foreign matter on the cleaning surface can be improved, and the frictional force takes in and removes the foreign matter into the opening of the cleaning surface. I was able to.

1, 1A, 1B, 1C ... Cleaning sheet 2, 2a, 2b ... Resin layer 3 ... Bubbles 7, 7a, 7b ... Adhesive 8 ... Base material P, P1, P2 ... Cleaning surface

The present invention has industrial applicability as an IC card reader that performs data communication with a contact type IC card and a cleaning sheet for cleaning a transport path inside the IC card reader.

Claims (11)

A first resin layer made of a foam having a first cleaning surface for cleaning an object to be cleaned is provided.
The first resin layer is a connecting cell having a plurality of bubbles extending in the thickness direction in the foam, and at least a part of the plurality of cells adjacent to each other is connected to each other.
A cleaning sheet having an opening formed from a part of the plurality of bubbles of the first resin layer on the first cleaning surface. The maximum diameter of the connected bubbles parallel to the first cleaning surface of the first resin layer exists inside the first resin layer.
The cleaning sheet according to claim 1. A base material arranged on the side of the first resin layer opposite to the first cleaning surface is further provided.
The cleaning sheet according to claim 1 or 2. The average opening diameter of the openings on the first cleaning surface is 5.0 to 300 μm.
The cleaning sheet according to any one of claims 1 to 3. The opening ratio of the opening on the first cleaning surface is 10 to 60%.
The cleaning sheet according to any one of claims 1 to 4. A second resin layer made of a foam having a second cleaning surface for cleaning the object to be cleaned is provided on the side of the first resin layer opposite to the first cleaning surface.
The second resin layer is a connecting cell having a plurality of bubbles in the foam and at least a part of the plurality of bubbles is connected to each other.
On the second cleaning surface, an opening formed from a part of the connecting bubbles of the second resin layer is formed.
The cleaning sheet according to any one of claims 1 to 5. Further, a base material arranged on one surface side of the first resin layer and one surface side of the second resin layer is further provided.
The base material is arranged on the opposite side of the first resin layer to the first cleaning surface and on the opposite side of the second resin layer to the second cleaning surface.
The cleaning sheet according to claim 6. The maximum diameter of the connected bubbles parallel to the second cleaning surface of the second resin layer exists inside the second resin layer.
The cleaning sheet according to claim 6 or 7. The first resin layer and the second resin layer contain a polyurethane resin.
The cleaning sheet according to any one of claims 1 to 8. A cleaning method comprising a step of cleaning an object to be cleaned using the cleaning sheet according to any one of claims 1 to 9. The cleaning method according to claim 10, further comprising a reading unit for reading card information by contact with the object to be cleaned.