JP2017093509A - Cleaning sheet and method for manufacturing same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cleaning sheet having excellent dust collecting ability to collect dust ranging from dust with a small diameter to dust with a large diameter such as soil dust.SOLUTION: A cleaning sheet according to the present invention is formed from base material non-woven fabric that includes thermoplastic fiber as a main material. The base material non-woven fabric is not applied with a surfactant and carries a chemical solution. The base material non-woven fabric before carrying the chemical solution has a wet tension of 60 mN/m or higher at an atmospheric temperature of 20°C. The chemical solution is formed of alcohol that has a surface tension of 45 mN/m or higher and a vapor pressure of 267 Pa or lower at an atmospheric temperature of 20°C. The base material non-woven fabric carries 5 to 10 mass% of the chemical solution with respect to the mass of the base material non-woven fabric. The cleaning sheet according to the present invention is manufactured through a plasma processing step in which one surface of a base material non-woven fabric 20 including thermoplastic fiber as a main material is subjected to plasma that has been generated under an atmospheric pressure by a remote-type plasma device 10 using processing gas.SELECTED DRAWING: Figure 3

Description

  The present invention relates to a cleaning sheet using a substantially dry dry nonwoven fabric.

  Conventionally, as a dry cleaning sheet, a base sheet such as a woven fabric or a non-woven fabric is generally provided with a chemical solution such as an oily substance. Adsorption is removed by “wetting”. For example, Patent Document 1 discloses that a chemical solution having a surface tension of 45 mN / m or more and a vapor pressure of 267 Pa or less at an atmospheric temperature of 20 ° C. is applied to a non-woven substrate sheet containing hydrophilic synthetic fibers. A dry cleaning sheet provided in the range of 3 to 95% by weight with respect to the weight is described. Further, Patent Document 1 describes glycerin as a specific example of the chemical solution, and further, hydrophilic synthetic fibers that are constituent fibers of the base sheet are hydrophilic to inherently hydrophobic fibers made of a hydrophobic synthetic resin. It has been described that a product subjected to a chemical treatment can be used, and as a hydrophilic treatment of such a fiber, a fiber surface adhesion treatment with a general fiber surfactant or kneading into a fiber is described. .

  Conventionally, for the purpose of coating treatment, hydrophilization treatment, water repellency treatment, sterilization treatment, and the like, a plasma treatment method has been applied to an object to be treated such as cloth. A so-called remote plasma type batch type plasma apparatus is described in which a region and a material processing region are separated. According to the plasma device described in Patent Document 2, it is said that a living body or a material having a low melting point that is subject to discharge damage or heat damage in general plasma irradiation can be used as a processing object.

  Patent Document 3 discloses that a polyolefin nonwoven fabric is subjected to corona discharge treatment or atmospheric pressure plasma discharge treatment so that the nonwoven fabric has a wetting tension of 35 to 55 mN / m, and then a hydrophilic agent such as a surfactant is applied to the nonwoven fabric. It is described that a hydrophilic polyolefin nonwoven fabric is produced by applying it by an immersion method, a spray method, a coating method, or the like. The hydrophilic polyolefin nonwoven fabric described in Patent Document 3 is excellent in hydrophilicity and durable hydrophilicity, and is said to be useful as industrial materials such as filters, wipers, battery separators, and sanitary material surface materials such as paper diapers and sanitary napkins. ing.

JP 2008-295886 A JP 2011-222404 A JP 2004-156163 A

  The cleaning sheet described in Patent Document 1 can collect from relatively small dust to relatively large dust such as bread crumbs and hair, and is useful as a cleaning sheet for home and business use. However, there is room for improvement in the collection performance of dust having a relatively large particle size, such as dirt and dust usually found in indoors of ordinary households.

  An object of the present invention is to provide a cleaning sheet that is excellent in dust collection performance and can collect dust having a small particle size to dust having a large particle size such as soil dust.

  The present invention is a cleaning sheet in which a chemical liquid is supported on a base nonwoven fabric mainly composed of thermoplastic fibers and not provided with a surfactant, and the ambient temperature of the base nonwoven fabric before supporting the chemical liquid The wetting tension at 20 ° C. is 60 mN / m or more, the chemical solution is made of alcohol having a surface tension of 45 mN / m or more and a vapor pressure of 267 Pa or less at an atmospheric temperature of 20 ° C., and the amount of the chemical solution supported by the base nonwoven fabric Is a cleaning sheet that is 5% by mass or more and 10% by mass or less with respect to the mass of the base nonwoven fabric.

  The present invention also includes a plasma processing step in which plasma generated at atmospheric pressure by a remote plasma apparatus using a processing gas is brought into contact with one surface of a base nonwoven fabric mainly composed of thermoplastic fibers, and the plasma processing step. And a step of applying a chemical solution composed of an alcohol having a surface tension of 45 mN / m or more and a vapor pressure of 267 Pa or less at an atmospheric temperature of 20 ° C. to the passed substrate nonwoven fabric.

  According to the cleaning sheet of the present invention, not only dust having a relatively small particle size but also dust having a large particle size such as dirt and dust which was not easily collected by a conventional dry cleaning sheet can be easily collected. can do. In addition, since the cleaning sheet of the present invention is of a dry type, it can be used for easy cleaning. For example, the cleaning tool can be easily cleaned by holding the cleaning tool with one hand in a state of being mounted on the cleaning tool.

FIG. 1 is a perspective view schematically showing one embodiment of the cleaning sheet of the present invention. FIG. 2 is a cross-sectional view schematically showing a cross section taken along line II of FIG. FIG. 3 is a schematic view of one embodiment of a plasma treatment step in the method for producing a cleaning sheet of the present invention.

  The cleaning sheet of the present invention includes a base nonwoven fabric and a chemical liquid carried on the base nonwoven fabric. 1 and 2 show an embodiment of the cleaning sheet of the present invention. As shown in FIGS. 1 and 2, the cleaning sheet 1 according to the present embodiment is configured to include a sheet-like support 3 arranged inside the base nonwoven fabric 2 in addition to the base nonwoven fabric 2. ing. The support 3 is mainly an auxiliary member for ensuring the shape retention of the base nonwoven fabric 2, and the base nonwoven fabric 2 is directly related to the main functions of the cleaning sheet 1 such as dust collection. is there.

  In the cleaning sheet 1, the constituent fibers of the base nonwoven fabric 2 are intertwined with each other and are also intertwined with the support 3, and the base nonwoven fabric 2 and the support 3 are integrated. An intertwined state is formed. The base nonwoven fabric 2 is a so-called spunlace nonwoven fabric that is formed by hydroentangling a fiber web manufactured by a known card method. Since spunlace nonwoven fabric is formed only by entanglement of constituent fibers, it is free of constituent fibers compared to fiber aggregates formed only by fusing or bonding constituent fibers, such as air-through nonwoven fabric and spunbond nonwoven fabric. The degree is great. For this reason, the dust collecting performance by the constituent fibers is excellent, the touch is soft, and it is easy to follow the surface to be cleaned, and it is difficult to scratch the surface to be cleaned. As shown in FIG. 2, both surfaces of the support 3 are each covered with a base nonwoven fabric 2. That is, the one surface 1a of the cleaning sheet and the other surface 1b located on the opposite side are each formed from the base nonwoven fabric 2.

  The support 3 has a plurality of through-holes through which the constituent fibers of the base nonwoven fabric 2 can pass, and the base web nonwoven fabric 2 or a fiber web that is a forming material (nonwoven fabric precursor) can be integrated in an entangled state. Shaped carrier. As such a sheet-like carrier, for example, a net-like sheet represented by a grid-like net or a perforated resin film can be used. In addition, a woven fabric having a relatively large mesh space such as a gauze-like woven fabric, or a nonwoven fabric having fiber voids that can be integrated in an entangled state by superimposing fiber webs on one or both sides. Various nonwoven fabrics having pores can also be used as a sheet-like carrier constituting the support 3. Note that if the support 3 (sheet-like carrier) is made of paper, the paper support 3 may absorb the chemical solution, so it is preferable not to use paper as the material of the support 3. .

  As shown in FIGS. 1 and 2, a large number of convex portions 4 and concave portions 5 are formed on one surface 1 a and the other surface 1 b of the cleaning sheet 1. The convex portion 4 is formed by projecting the base nonwoven fabric 2 from the one surface side to the other surface side, the concave portion 5 is located between the adjacent convex portions 4, 4, and the cleaning sheet 1 is uneven as a whole. It has a shape. The plurality of convex portions 4 are substantially the same size, have a slightly elongated and narrow mountain shape, and are regularly provided on each of the one surface 1a and the other surface 1b. In the form shown in the figure, the concave portions 5 exist around the entire circumference of each convex portion 4, that is, the plurality of convex portions 4 have independent shapes, but the formation pattern of the convex portions 4 is limited to this. For example, the cleaning sheet 1 may be continuous over the entire length in one direction.

  In addition, the cleaning sheet of the present invention may not have unevenness on the surface, and the surface of the base nonwoven fabric constituting this may be a flat surface having substantially no unevenness. However, since the surface of the cleaning sheet (base nonwoven fabric), particularly the surface that comes into contact with the surface to be cleaned, is provided with a concavo-convex structure such as the convex portion 4 and the concave portion 5, dust collection by the concavo-convex structure itself. Therefore, the dust collecting performance can be further improved in combination with the dust collecting effect by the chemical liquid carried on the base nonwoven fabric.

The apparent thickness T of the cleaning sheet 1, that is, the distance T (see FIG. 2) between the top of the convex portion 4 on the one surface 1a side and the top of the convex portion 4 on the other surface 1b side is preferably 1 mm or more. Preferably it is 1.3 mm or more, and preferably 5 mm or less, more preferably 3 mm or less.
The substantial thickness t (see FIG. 2) of the cleaning sheet 1 is preferably 0.1 mm or more, more preferably 0.4 mm or more, and preferably 2 mm or less, more preferably 1.5 mm or less.
The height h (see FIG. 2) of the convex portion 4 is preferably 0.6 mm or more, more preferably 0.9 mm or more, and preferably 4.9 mm or less, more preferably 2 mm or less.
The apparent thickness and substantial thickness of the cleaning sheet and the height of the protrusions were each set to a total mass of 30 g by placing a weight on a 10 cm × 5 cm acrylic plate having a rectangular shape in plan view on the cleaning sheet to be measured. A load is applied to the cleaning sheet in the thickness direction at 30 gf / 50 cm ² (= 59 Pa), and the cross section of the cleaning sheet is observed with an optical microscope in this state.

  The base nonwoven fabric according to the present invention is a fiber assembly mainly composed of thermoplastic fibers. Here, “mainly composed of thermoplastic fibers” means that the proportion of thermoplastic fibers in all the constituent fibers of the base nonwoven fabric is 95% by mass or more. The proportion of thermoplastic fibers in all the constituent fibers of the base nonwoven fabric is preferably 98% by mass or more, and may be 100% by mass.

  As the thermoplastic fiber that can be used as the constituent fiber of the base nonwoven fabric, those that can be used for various nonwoven fabrics can be used without particular limitation. For example, polyesters such as polyethylene terephthalate (PET) and polybutylene terephthalate (PBT). Resins; Polyolefin resins such as polyethylene (PE) and polypropylene (PP); Polyamide resins such as nylon (registered trademark) and nylon 6; Polyacrylic resins such as ethyl polyacrylate; Polyvinyl chloride resins; Polyurethane resins Resin; Cellulose derivative resin such as cellulosic resin and chemical modification product thereof (for example, thermoplastic cellulose resin); Manufacture one kind of thermoplastic resin such as polylactic acid resin alone or in combination of two or more kinds The thermoplastic fiber made is mentioned. Moreover, as a fiber structure of a thermoplastic fiber, the single fiber which consists of 1 type of resin may be sufficient, and the composite fiber containing 2 or more types of resin from which melting | fusing point differs may be sufficient. As the composite fiber, a core-sheath type in which a resin having a relatively low melting point (low melting point resin) is a sheath and a resin having a relatively high melting point (high melting point resin) is a core; low melting point resin and high melting point resin Can be used in the present invention.

  Examples of preferred thermoplastic fibers as the constituent fibers of the base nonwoven fabric include polyester fibers, polyolefin fibers and polyamide fibers as single fibers, and two or more types of polyolefin resins as composite fibers. Examples include composite fibers, composite fibers of polyolefin resins and polyester resins, composite fibers of polyolefin resins and polyamide resins, and composite fibers of polyamide resins and polyester resins. The composite fiber is preferably a core-sheath type.

  The average fiber diameter of the constituent fibers of the base nonwoven fabric is preferably 0.1 μm or more, more preferably 1 μm or more, and preferably 1000 μm or less, more preferably 100 μm or less, from the viewpoint of dust collection. If the average fiber diameter of the constituent fibers of the base nonwoven fabric is too small, the entanglement between the fibers becomes too strong at the time of manufacturing the base nonwoven fabric, the degree of freedom of the fibers is impaired, and the hair collection performance as a cleaning sheet decreases. Conversely, if it is too large, the entanglement between the fibers during the production of the base nonwoven fabric will be insufficient, and the fibers may easily fall off from the base nonwoven fabric. The average fiber diameter here refers to 10 small sample pieces taken randomly from the nonwoven fabric, photographed 300 to 3000 times with a scanning electron microscope or the like, and image analysis software such as WinROOF (manufactured by Mitani Corp.). It means what is obtained by measuring 100 fiber diameters, 10 from each sample, and rounding off the first decimal place of the average value.

The basis weight of the base non-woven fabric is not particularly limited, and may be set as appropriate in consideration of processability, economy, etc., but when a concavo-convex structure as shown in the figure is given, perforation occurs. From the viewpoints of prevention of the above, sufficient bulkiness, and maintenance of bulkiness, it is preferably 30 g / m ² or more, more preferably 45 g / m ² or more, and preferably 100 g / m ² or less, more preferably 70 g / m ² or less.

  The base nonwoven fabric according to the present invention is not provided with a surfactant. That is, the constituent fiber (thermoplastic fiber) of the base nonwoven fabric according to the present invention has no surfactant attached to the surface after the base nonwoven fabric is formed, and the surface active agent is not present in the fiber. The agent is not kneaded and does not contain a surfactant. The reason is to prevent the chemical solution carried on the base nonwoven fabric from being altered by the surfactant. That is, in this type of dry cleaning nonwoven fabric, a hydrophilizing agent typified by a surfactant is usually used as described in Patent Document 1 in order to facilitate the carrying of a certain amount of chemical solution on the base nonwoven fabric. The base non-woven fabric is subjected to a hydrophilic treatment, specifically, for example, a surface treatment of the constituent fiber with a surfactant or kneading into the constituent fiber. When a surfactant is applied to the base nonwoven fabric, the surfactant is incorporated in the chemical solution when a specific chemical solution (chemical solution having a high surface tension and excellent dust collecting ability) described later is supported on the nonwoven fabric. The surface tension of the chemical solution may change due to elution. Therefore, in the present invention, as the base nonwoven fabric on which the chemical solution is carried, one not provided with a surfactant is employed. In addition, “the surfactant is not applied” means that the surfactant is not intentionally applied to the base nonwoven fabric. For example, a small amount of an antistatic agent (cationic type) is used for the purpose of an antistatic effect. A form to which a kind of surfactant is added can be allowed without departing from the spirit of the present invention. Even if a trace amount of antistatic agent is applied to the base nonwoven fabric, the liquid wettability to the constituent fiber surface is not substantially affected.

  However, when the surfactant is not applied to the base nonwoven fabric mainly composed of thermoplastic fibers, the liquid droplets of the chemical liquid are attached to only a small part of the fiber surface, and the entire surface of the fiber is covered with the chemical liquid. It does not become wet, and it becomes difficult to carry a certain amount or more of the chemical solution on the base nonwoven fabric, so that there is a risk that the dust collecting performance of the cleaning sheet will be insufficient. In consideration of such a point, it is conceivable to use inherently hydrophilic fibers such as cellulose fibers such as rayon and cotton, or polyvinyl alcohol fibers as part of the constituent fibers of the base nonwoven fabric. However, if the base non-woven fabric inherently contains a certain amount or more of hydrophilic fibers, when the base non-woven fabric is loaded with a chemical solution, the chemical solution is contained inside the hydrophilic fibers such as cellulosic fibers that are constituent fibers. Since the chemical solution absorbed in the fibers does not contribute to the dust collection performance, a large amount of chemical solution is required to fully develop the dust collection performance of the chemical solution. For example, in the case of a base nonwoven fabric mainly composed of cellulose fibers, it is necessary to carry a chemical solution of 50% by mass or more with respect to the mass of the nonwoven fabric, and a wet cleaning sheet rather than a dry type is obtained. Increasing the amount of the chemical solution may increase the manufacturing cost, and the chemical solution may ooze out to the outside due to the load applied during use, making it easy to use and easy to handle as a dry cleaning sheet. May be lost. In particular, polyvinyl alcohol fibers are easily soluble in warm water of at least 80 ° C., and the fibers are deformed or dissolved in the process of drying water when producing a base nonwoven fabric by the spunlace manufacturing method. Since there exists a possibility, there also exists a situation that it is difficult to apply to the spunlace nonwoven fabric used preferably as a base material nonwoven fabric. As described above, cellulose fibers and polyvinyl alcohol fibers are not suitable as constituent fibers of the base nonwoven fabric on which the chemical solution is carried.

  Therefore, in the present invention, as a result of various investigations focusing on the wetting tension of the base nonwoven fabric, the wetting tension at an ambient temperature of 20 ° C. of the base nonwoven fabric before the chemical solution is supported is 60 mN / m or more, preferably 62 mN / m. As described above, more preferably 65 mN / m or more, so that the base nonwoven fabric is essentially composed of hydrophobic thermoplastic fibers and is not provided with a surfactant. It has been found that a sufficient amount of chemical solution can be carried in the collection. And by carrying | supporting the chemical | medical solution with the high dust collection performance mentioned later on such a base material nonwoven fabric, the dry cleaning sheet with a very high dust collection performance comes to be obtained. As a means for setting the wetting tension of the base nonwoven fabric within the above range, plasma treatment of the base nonwoven fabric is preferable. This will be described later. The wetting tension of the base nonwoven fabric is measured by the following method.

<Method for measuring wet tension of nonwoven fabric>
In an environmental region with an atmospheric temperature of 20 ° C., a nonwoven fabric to be measured is horizontally stretched in the air, 15 μL of a wet tension test solution is dropped on the upper surface of the nonwoven fabric, and 20 seconds after the test solution is dropped, The state of the test solution is visually observed. In the observation, when the test solution permeates in the thickness direction of the nonwoven fabric or diffuses in the surface direction, the test solution is changed to a test solution having a larger surface tension and the same operation is performed. And, when the test liquid cannot penetrate the nonwoven fabric and the droplet remains on the upper surface of the nonwoven fabric, or when the upper surface is hardly diffused and does not diffuse in the surface direction, the dripping operation immediately before such case The surface tension of the test liquid used in the above, that is, the test liquid having the maximum surface tension among the test liquids that can permeate or diffuse through the nonwoven fabric is defined as the wetting tension at an ambient temperature of 20 ° C. of the nonwoven fabric. As the wetting tension test solution, a mixed solution of ethylene glycol monoethyl ether, formamide, methanol and water prepared according to JIS K 6768: 1999 is used, and the surface tension is adjusted by appropriately changing the mixing ratio of each component. Such a wet tension test solution is commercially available, for example, from Wako Pure Chemicals under the trade name of a wet tension test mixture.

  In the cleaning sheet of the present invention, the chemical solution carried on the base nonwoven fabric is made of alcohol having a surface tension of 45 mN / m or more at an atmospheric temperature of 20 ° C. Alcohol serves as a dust adsorbent. According to the knowledge of the present inventors, the chemical liquid carried on the base nonwoven fabric is composed of alcohol having a surface tension in such a specific range, so that particles having a relatively large particle size such as dirt dust, particularly It has been found that the trapping ability of particles having a particle size of 150 μm or more (more specifically, a particle size of 150 to 300 μm) is extremely improved. Since particles having a particle size of 150 μm or more have a noticeable graininess perceived by the sole, the ability to reliably collect particles having such a particle size is extremely useful for improving the cleaning performance of the cleaning sheet. Is advantageous.

Alcohol having a surface tension of 45 mN / m or more at an atmospheric temperature of 20 ° C. has a high adsorption ability for particles having a relatively large particle size such as soil dust to be collected. The reason for this is not clear, but it is assumed that soil dust is mainly made of silica sand (SiO ₂ ) and the surface is hydrophilic, so it has a high affinity with alcohol with high surface tension. . Due to this adsorption force, even particles having a large particle diameter can be reliably collected. From such a point of view, the higher the surface tension of the alcohol supported on the base nonwoven fabric at an atmospheric temperature of 20 ° C. is, the higher, more specifically, 46 mN / m or more, and particularly preferably 50 mN / m or more. The upper limit of the surface tension of the alcohol is not particularly limited. However, if the surface tension is high at about 73 mN / m, particularly about 60 mN / m, the performance of adsorbing and collecting large particles is sufficiently exhibited. The

  The method for measuring the surface tension is as follows. That is, in an environmental region of an ambient temperature of 20 ° C. and a humidity of 65%, a plate method (Wilhelmi method) was used in an automatic surface tension meter (CBVP-2 type) manufactured by Kyowa Interface Science (a platinum plate was used as the measurement plate). Measure in automatic measurement mode.

  By the way, regarding the chemical solution carried on the base nonwoven fabric, even if the surface tension is high and the dust adsorption capability is high, the chemical solution is stored while the cleaning sheet is stored for a long time if the volatility is high. Volatilization may occur and the desired collection performance may not be exhibited. Therefore, in the present invention, an alcohol having further low volatility in addition to the above-described high surface tension is used as the chemical solution carried on the base nonwoven fabric. Specifically, the alcohol contained in the chemical supported on the base nonwoven fabric has a vapor pressure at an atmospheric temperature of 20 ° C. of 267 Pa or less, preferably 133 Pa or less, more preferably 26.6 Pa or less. By carrying a chemical solution containing such a low-volatile alcohol on a base nonwoven fabric to form a cleaning sheet, it is possible to collect large particle size dust having a particle size of 150 μm or more even after long-term storage. It becomes possible to make it high. The lower the vapor pressure of the alcohol supported on the base nonwoven fabric at an atmospheric temperature of 20 ° C., the better. Specifically, the vapor pressure is preferably 13.3 Pa or less, particularly preferably 4.5 Pa or less. The lower limit value of the vapor pressure of the chemical solution is not particularly limited, but if the vapor pressure is as low as 0.1 Pa, particularly about 1 Pa, volatilization of the chemical solution is sufficiently suppressed.

  As the alcohol satisfying the above-described surface tension and vapor pressure conditions, a polyhydric alcohol is preferably used. Examples of the polyhydric alcohol include glycerin, ethylene glycol (1,2-ethanediol), 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, triethylene glycol, and triethanol. An amine, 2,2'- thiodiethanol etc. are mentioned, These 1 type can be used individually or in combination of 2 or more types. Among these polyhydric alcohols, glycerin, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, diethylene glycol, triethylene glycol are particularly preferable from the viewpoint of safety and economy. Glycerol is particularly preferable.

  In the cleaning sheet of the present invention, the chemical liquid carried on the base nonwoven fabric is preferably 100% of a specific alcohol that satisfies the above-described surface tension and vapor pressure conditions. It is allowed to mix 10% or less in the specific alcohol within the range satisfying the vapor pressure condition. Further, the chemical liquid carried on the base nonwoven fabric contains appropriate components other than the specific alcohol satisfying the above-described surface tension and vapor pressure conditions, for example, various additives such as fragrances and preservatives. However, as is clear from the above description, it is preferable that these additives do not lower the surface tension of the specific alcohol or do not contain a surfactant.

  In addition, with respect to the amount of the chemical solution supported on the base nonwoven fabric, it is preferable that the amount of the chemical solution supported is as small as possible from the viewpoint of manufacturing cost, handling property of the cleaning sheet, and the like. The effect of improving the collection performance is poor. From such a viewpoint, the amount of the chemical solution supported by the base nonwoven fabric is 5% by mass or more, preferably 5.5% by mass or more, more preferably 6% by mass or more, and 10% by mass. It is not more than mass%, preferably not more than 8 mass%, more preferably not more than 7.5 mass%. As described above, the cleaning sheet of the present invention has a relatively small amount of chemical liquid of 5% by mass or more and 10% by mass or less because the wetting tension at an ambient temperature of 20 ° C. of the base nonwoven fabric before carrying the chemical liquid is 60 mN / m or more. Even with the loading amount, since the entire surface of the constituent fibers of the base nonwoven fabric is wetted by the chemical solution (a state in which the chemical solution is coated on the fiber surface in a sheath shape), a sufficient cleaning effect can be achieved and the chemical solution is small. Due to the carrying amount, it is difficult to cause an increase in manufacturing cost, and furthermore, there is little possibility that the chemical solution oozes out to the outside due to a load applied at the time of use, and it has the ease of use and the handleability unique to a dry cleaning sheet.

  Next, the manufacturing method of the cleaning sheet of the present invention will be described. The manufacturing method of the cleaning sheet of the present invention is suitable for manufacturing the cleaning sheet of the present invention described above, and 1) a plasma treatment process in which plasma is brought into contact with one surface of a base nonwoven fabric mainly composed of thermoplastic fibers. And 2) a step of applying a chemical solution to the base nonwoven fabric that has undergone the plasma treatment step. In the following method for manufacturing a cleaning sheet according to the present invention, portions different from the above-described cleaning sheet according to the present invention will be mainly described, and the description of the cleaning sheet will be appropriately applied to portions not specifically described. Is done.

  The base nonwoven fabric subjected to the plasma treatment step can be manufactured according to a known nonwoven fabric manufacturing method. For example, in the cleaning sheet 1 shown in FIGS. 1 and 2, the base nonwoven fabric 2 and the support 3 form an integral entangled state. The integrated product can be manufactured using a known hydroentanglement method. Specifically, for example, a fiber web (precursor of the base nonwoven fabric 2) manufactured according to a conventional method using a card machine is superposed on each of both surfaces of a separately prepared support 3 to obtain a polymer, and hydroentanglement The base nonwoven fabric 2 is formed by entanglement between the constituent fibers of both fiber webs in the polymer, and the base nonwoven fabric 2 and the support 3 are entangled to integrate the two. And the integrated material of the base material nonwoven fabric of a structure as shown in FIG. 2 and a support body is obtained. For the production of the nonwoven fabric by hydroentanglement, for example, an apparatus described in Japanese Patent Application Laid-Open No. 2001-336052 related to the previous application of the present applicant can be used.

  FIG. 3 shows an outline of one embodiment of the plasma processing step in the method for manufacturing a cleaning sheet of the present invention. The plasma apparatus 10 used in the present embodiment is a so-called remote plasma apparatus that blows out plasma G generated between the electrodes 12 and 12 toward a processing target disposed outside the pair of electrodes 12 and 12. . The plasma apparatus 10 includes a processing head 11 disposed to face a processing object, and a pair of electrodes 12 and 12 are disposed inside the processing head 11 so as to face each other. A solid dielectric layer is formed. One of the electrodes 12, 12 is connected to the power source 13 and the other is electrically grounded, and the voltage supply from the power source 13 causes the space between the electrodes 12, 12 to discharge at atmospheric pressure or in the vicinity thereof. It becomes space 14. The processing gas inlet 15 side in the discharge space 14 communicates with the supply source 16 of the processing gas G ′. In the plasma apparatus 10 having such a configuration, the processing gas G ′ is introduced from the supply source 16 into the discharge space 14 to generate plasma G (plasmaized processing gas G ′), and the plasma G is processed into the processing head. 11 is blown out from the gas blowout port 17 at the lower end, and blown below the gas blowout port 17 to one side (upper surface) of the object to be processed (base nonwoven fabric 20). The base nonwoven fabric 20 is transported in the direction indicated by the symbol MD during processing by the plasma apparatus 10 by the transporting conveyor 19 disposed below the processing head 11 (gas blowing port 17). As the processing gas G ′, one or more selected from the group consisting of nitrogen and oxygen, or the atmosphere can be used.

  In the manufacturing method of this embodiment, the atmospheric pressure remote plasma treatment is performed using the plasma apparatus 10 prior to supporting the chemical solution on the base nonwoven fabric mainly composed of thermoplastic fibers. Specifically, the separately manufactured continuous belt-like base material nonwoven fabric 20 is conveyed by the conveyer 19 with its longitudinal direction coinciding with the conveyance direction MD, while one surface of the substrate nonwoven fabric 20 being conveyed, that is, the processing head 11 The plasma G (plasmaized processing gas G ′) generated under the atmospheric pressure by the plasma apparatus 10 using the processing gas G ′ is brought into contact with the opposite surface. By carrying out such a plasma treatment step, the wetting tension of the base nonwoven fabric 20 at an atmospheric temperature of 20 ° C. can be set to 60 mN / m or more, whereby the surface tension is high and dust trapping is performed in the chemical solution application step of the next step. A practically sufficient amount of the chemical solution having excellent collecting ability can be supported on the base nonwoven fabric 20.

  In such remote plasma processing, the plasma generation region (discharge space) and the processing object processing region are separated from each other, so that electrons existing in the discharge space do not collide with the processing object, and the processing object Has the advantage that it is not subject to electric field damage such as discharge damage or heat damage. In addition to the remote method, plasma processing includes a so-called direct method in which an object to be processed is disposed in a discharge space (between a pair of electrodes). In direct plasma processing, an object to be processed is an electric field. There is concern about damage, and for example, when a nonwoven fabric is subjected to direct plasma treatment, inconvenience such as discoloration may occur. In addition, as shown in FIG. 3, the remote type plasma treatment can continuously process the object to be processed, and therefore has an advantage that the production efficiency is higher than the batch type processing method. Also have.

  In the plasma processing step of the present embodiment, the other side of the base nonwoven fabric 20 (the object to be processed) being transported, that is, the side opposite to the surface on which the plasma G is sprayed, by a vacuum means (not shown) provided in the transport conveyor 19. Aspirate from. By such plasma suction, the reforming efficiency of the base nonwoven fabric by plasma can be improved, and the realization of the wetting tension of 60 mN / m or more at the atmospheric temperature of 20 ° C. of the base nonwoven fabric can be further ensured. At the same time, the substrate nonwoven fabric 20 (processing object) being transported is fixed on the transport conveyor 19 by the suction of the plasma, so that the substrate nonwoven fabric 20 (processing object) is sprayed when the plasma G is sprayed. It is also possible to prevent meandering on the transport conveyor 19. The suction of the plasma G is preferably performed at least before and after the point of time when the plasma G is blown onto the base nonwoven fabric 20, that is, the plasma G is blown away from the blowout port 17 by a predetermined distance in the transport direction MD and in the opposite direction. It is preferable to carry out over the position. As a vacuum means for sucking the plasma G, known suction means capable of sucking various gases can be used.

  Moreover, in this embodiment, as shown in FIG. 3, before making a plasma contact the base nonwoven fabric 20 (process target object), the base nonwoven fabric 20 is heated using the heating means 18. As shown in FIG. The heating means 18 in this embodiment is a blowing device for hot air (heater gas), and is a surface (plasma-treated surface) on which the plasma in the substrate nonwoven fabric 20 is sprayed upstream of the plasma G blowing port 17 in the conveying direction MD. ), And hot air is blown directly onto the plasma processing surface to heat it. By such heat treatment of the base nonwoven fabric, the reforming efficiency of the base nonwoven fabric by the subsequent plasma spraying is improved, and the realization of the wetting tension of 60 mN / m or more at the atmospheric temperature of 20 ° C. becomes even more reliable. obtain. In addition, the heating method of the base nonwoven fabric is not limited to the blowing of hot air in a form using an apparatus in which the plasma processing means and the heating means (hot air blowing device) are integrated as shown in FIG. It is also possible to use a plasma treatment means and a separate dryer, and transport the base nonwoven fabric to the dryer before plasma contact, and spray hot air in the dryer.

  Regarding the heating conditions of the base nonwoven fabric, for example, in the case where the transport speed of the base nonwoven fabric is 50 m / min, the hot air blown to the base nonwoven fabric is used from the viewpoint of making the effect of the heat treatment more reliable. The heating condition is such that the temperature at the surface of the base non-woven fabric (surface to be plasma treated) is about the glass transition temperature of the constituent fibers of the base non-woven fabric plus 150 ° C. or higher and the melting point of the constituent fibers plus about 50 ° C. or lower. preferable. The “glass transition temperature of the constituent fibers” referred to here means the highest temperature among the plurality of glass transition temperatures when the base nonwoven fabric contains a plurality of constituent fibers having different glass transition temperatures. . The same is true for “melting point of constituent fibers”. When the conveyance speed of the base nonwoven fabric exceeds 50 m / min, it is preferable to shift the hot air temperature to the high temperature side according to the increase in the speed, and when the conveyance speed falls below 50 m / min, the speed It is preferable to shift the hot air temperature to a low temperature side according to the amount of decrease. Under such heating conditions, it is possible to increase the plasma modification efficiency by activating the thermal motion of the resin constituent molecules in the constituent fibers of the base nonwoven fabric within a range that does not damage the fiber form / nonwoven form. Become.

  According to the knowledge of the present inventors, the wet tension at the atmospheric temperature of 20 ° C. of the base nonwoven fabric can be increased as the number of times of plasma contact with the base nonwoven fabric (the number of plasma treatments) increases. Therefore, for example, as shown in FIG. 3, after the plasma G is sprayed on one surface of the base nonwoven fabric 20, the plasma G is sprayed again on the one surface or the other surface of the base nonwoven fabric 20 in the same manner. A total of two plasma treatments may be performed on the nonwoven fabric 20. The number of plasma treatments of the base nonwoven fabric may be three or more. That is, the manufacturing method of the cleaning sheet of the present invention includes a mode in which plasma is brought into contact with one side or both sides of the base nonwoven fabric one or more times.

  In the method for producing a cleaning sheet of the present invention, a chemical solution is applied to the base nonwoven fabric that has undergone the above-described plasma treatment step. As described above, the chemical solution to be applied to the plasma-treated base non-woven fabric is a chemical solution made of alcohol having a surface tension of 45 mN / m or more and a vapor pressure of 267 Pa or less at an atmospheric temperature of 20 ° C. As a method for applying the chemical solution, a known method used for applying this type of chemical solution to the sheet can be used without particular limitation, and examples thereof include spraying by spraying, impregnation, and application. Depending on the chemical solution, the viscosity may be high at room temperature. Therefore, it is desirable for handling of the chemical solution to be appropriately heated to lower the viscosity and then subjected to spraying, impregnation, coating, and the like by spraying. As a means for obtaining the cleaning sheet of the present invention by batch processing, the chemical solution is dissolved and diluted in a volatile solvent such as ethanol and then sprayed, impregnated, and applied by spraying to volatilize the volatile solvent. There is also.

  The cleaning sheet of the present invention manufactured by the above-described manufacturing method can be used for various applications utilizing its excellent dust collection performance, and particularly suitable for cleaning floor surfaces such as flooring. it can. It can also be used for cleaning furniture such as tables and desks, TVs, video decks, hard disk recorders, personal computers, refrigerators and other household appliances with a relatively large area.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to such examples.

[Examples 1 to 4]
A base nonwoven fabric for carrying a chemical solution was manufactured according to the procedure described in the publication using an apparatus described in JP-A-2001-336052. The configuration of the manufactured base nonwoven fabric is the same as that of the cleaning sheet 1 shown in FIGS. 1 and 2, and the base nonwoven fabric is arranged on each of both surfaces of the support to form an integral entangled state. As a whole, the base nonwoven fabric is uneven.
Specifically, a fiber web was obtained using PET fiber (average fiber diameter: 12 μm) as a raw material using a known card method. A polypropylene lattice net (interfiber distance: 8 mm, wire diameter: 300 μm) was used as the support, and after the fiber web was polymerized above and below it, it was entangled with jet water jets ejected from a plurality of nozzles under conditions of 1-5 MPa water pressure The laminated body which united and integrated and has a fiber assembly (spunlace nonwoven fabric) was obtained. Next, with respect to the obtained laminated body, on the patterning member of the structure shown to FIG. 4 (a)-FIG.4 (c) of Unexamined-Japanese-Patent No. 2001-336052, from several nozzles on the conditions of water pressure 1-5 Mpa. A jet stream was applied to give a convex shape, and a base nonwoven fabric having a concave and convex shape was obtained by hot air drying. The obtained base nonwoven fabric is a base nonwoven fabric mainly composed of thermoplastic fibers and not provided with a surfactant.
Next, atmospheric pressure plasma treatment was performed on the obtained base nonwoven fabric using an apparatus having the same basic configuration as the remote plasma apparatus 10 shown in FIG. Details of the conditions of the atmospheric pressure plasma treatment are as follows.
Next, alcohol is used as a chemical solution to prepare an ethanol diluted solution having a chemical concentration of 1% by mass. The ethanol diluted solution is sprayed on one surface of the base nonwoven fabric, and then allowed to stand at room temperature for 12 hours to volatilize ethanol. The target cleaning sheet was obtained.

(Plasma treatment conditions)
-Remote plasma device: Tough Plasma FPE20 (Fuji Machinery Manufacturing)
・ Distance between plasma outlet and object to be treated (base non-woven fabric): 5 mm
-Conveying speed of processing object during plasma processing: 50 m / min
・ Processing control method: Controlled by a two-axis robot (made by IAI) (processing over A4 size)
-Nitrogen (purity 99.9% or more, oxygen content 0.1% or less) was used as the processing gas, and the flow rate of the processing gas was 30 L / min.
-Heater gas was used to heat the object to be processed before plasma spraying. Air was used as the heater gas. The flow rate of the heater gas was 20 L / min, and the heating temperature (the temperature at the surface position of the processing object of the heater gas) was 220 ° C.
・ At the time of plasma treatment, suction was performed from the opposite side of the surface of the object to be treated where the plasma was sprayed.

[Comparative Examples 1-4]
A cleaning sheet was obtained in the same manner as in each Example except that the chemical solution was applied to the base nonwoven fabric without performing the plasma treatment. In addition, when liquid paraffin is used as a chemical solution, liquid paraffin diluted with chloroform to a concentration of 1% by mass is spray-sprayed on one surface of the base nonwoven fabric, and then allowed to stand at room temperature for 12 hours to volatilize chloroform. Thus, a cleaning sheet as a comparative example was obtained. The liquid paraffin used in the comparative example is a mixed liquid of 90% by mass of liquid paraffin and 10% by mass of Softanol 30 (manufactured by Nippon Shokubai).

〔Evaluation test〕
About the cleaning sheet | seat of each Example and a comparative example, the state of the chemical | medical solution in the surface of a constituent fiber and the dust collection performance were evaluated by the following method. The dust collection performance is 3 of large particle size dust (150 to 300 μm) obtained by screening hair, 7 types of JIS test dust (particle size: 3 to 80 μm), and 1 type of JIS test dust (44 to 300 μm). It was carried out by measuring the collection rate by the following method for each target. The results are shown in Table 1 below.

<State of chemical on the surface of the constituent fiber>
The state of the chemical solution on the surface of the constituent fibers of the base nonwoven fabric of the cleaning sheet to be evaluated is observed with an optical microscope (manufactured by Keyence, VHX-1000). A 3 cm × 3 cm test piece was cut from the cleaning sheet after carrying the chemical solution with a commercially available scissor or a push-off cutter, placed on the stage of the optical microscope, and observed with the magnification of the observation lens set to 200 times.
Ideally, the chemical solution has a high affinity for the fiber, and therefore, the state where the entire fiber surface is wetted by the chemical solution is ideal. In this case, the entire fiber surface is covered with the chemical solution (sheathed sheath state) ) Is observed. On the other hand, when the affinity of the chemical liquid to the fiber is low, it is observed that the liquid droplet of the chemical liquid adheres to only a part of the fiber surface (liquid repellent state).

<Hair collection rate>
The cleaning sheet to be evaluated was attached to Quickle Wiper (registered trademark), which is a cleaning tool made by Kao. 5 hairs of about 10 cm are spread on a flooring of about 30 cm × 90 cm (Wooddy A Excellite manufactured by Panasonic (Part No. VKSNZ)), and a cleaning sheet attached to the cleaning tool is placed on the hair and fixed. The number of hairs collected on the cleaning sheet after two reciprocal cleanings with a stroke (90 cm) was measured. This operation was carried out 6 times in succession to determine how many of 30 hairs were collected. The number of collected hairs was divided by 30 and multiplied by 100 to obtain the value as the hair collection rate (%).

<The collection rate of 7 kinds of JIS test dust (particle size 3 to 80 μm)>
The cleaning sheet to be evaluated was attached to Quickle Wiper (registered trademark), which is a cleaning tool made by Kao. Disperse 0.1g of 7 kinds of JIS test dust (Kanto loam layer, fine grain) on flooring (Wooddy A Excellite (Product No. VKSNZ) manufactured by Panasonic) about 100cm x 100cm (spread uniformly over the entire surface) ), The flooring was cleaned in four lines in one reciprocation. After this operation was repeated six times, the mass of the dirty cleaning sheet was measured. The amount of dust collected was calculated by subtracting the mass of the cleaning sheet previously measured before cleaning. The mass of the collected dust is divided by the total dust mass (0.6 g = 0.1 g × 6 times) dispersed, multiplied by 100, and the value is collected as the collection rate of 7 types of dust for JIS testing. (%).

<The collection rate of large particle size dust (particle size 150-300 μm)>
One type of test dust made by IWAMOTO MINEMAL CO was sieved, and those that passed through a mesh with a mesh size of 300 μm and turned on a mesh with a mesh size of 150 μm were collected. Using a tea strainer, 0.25 g of this dust was evenly spread over a square area of 8 cm × 8 cm on a flat board (black matte decorative board). The cleaning sheet to be evaluated, which was cut out to 10 cm × 10 cm, was gently piled so as to cover the dust that was scattered. Then, the sheet was pressed once and again in the vertical and horizontal directions using a roller having a width of 150 mm and a mass of 1 kg, and dust was adhered to the sheet. Subsequently, the mass A of the sheet to which the dust adhered was measured. The mass B of the sheet measured in advance before adhering the dust was subtracted from the mass A, and the mass C of the dust adhering to the sheet was determined. The value obtained by dividing the mass C by 0.25 g which is the initial dust mass and further multiplying by 100 was taken as the dust collection rate (%).

DESCRIPTION OF SYMBOLS 1 Cleaning sheet 2 Base nonwoven fabric 3 Support body 4 Convex part 5 Concave part 10 Remote type plasma apparatus 11 Processing head 12 Electrode 13 Power supply 14 Discharge space 15 Processing gas introduction port 16 Processing gas supply source 17 Gas blowing port 18 Heating means 19 Transport conveyor 20 Substrate nonwoven fabric G ′ Processing gas G Plasma

Claims (9)

A cleaning sheet in which a chemical solution is supported on a base nonwoven fabric mainly composed of thermoplastic fibers and not provided with a surfactant,
The wetting tension at an ambient temperature of 20 ° C. of the base nonwoven fabric before supporting the chemical solution is 60 mN / m or more,
The chemical solution comprises an alcohol having a surface tension of 45 mN / m or more and a vapor pressure of 267 Pa or less at an atmospheric temperature of 20 ° C.,
The amount of the chemical solution supported by the base nonwoven fabric is a cleaning sheet that is 5% by mass or more and 10% by mass or less with respect to the mass of the base nonwoven fabric.   The cleaning sheet according to claim 1, wherein the alcohol is a polyhydric alcohol.   The polyhydric alcohol is at least one selected from the group consisting of glycerin, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, diethylene glycol and triethylene glycol. Item 3. A cleaning sheet according to Item 2.   The cleaning sheet according to any one of claims 1 to 3, wherein an average fiber diameter of constituent fibers of the base nonwoven fabric is 0.1 µm or more and 1000 µm or less. A plasma treatment process in which plasma generated at atmospheric pressure by a remote plasma apparatus using a processing gas is brought into contact with one surface of a base nonwoven fabric mainly composed of thermoplastic fibers;
A method for producing a cleaning sheet, comprising: applying a chemical solution composed of an alcohol having a surface tension of 45 mN / m or more and a vapor pressure of 267 Pa or less at an atmospheric temperature of 20 ° C. to the substrate nonwoven fabric that has undergone the plasma treatment process.   The method for manufacturing a cleaning sheet according to claim 5, wherein the processing gas is one or more selected from the group consisting of nitrogen and oxygen, or air.   The said plasma treatment process WHEREIN: The manufacturing method of the sheet | seat for cleaning of Claim 5 or 6 which makes the said plasma contact one time or both surfaces of the said base nonwoven fabric once or more.   In the said plasma treatment process, the manufacturing method of the sheet | seat for cleaning as described in any one of Claims 5-7 which attracts | sucks the said plasma from the other surface side of the said base-material nonwoven fabric.   The manufacturing method of the cleaning sheet as described in any one of Claims 5-8 which heats this base nonwoven fabric before making the said plasma contact the said base nonwoven fabric.

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