Cleaning sheet

Abstract

The present invention provides a cleaning sheet that offers excellent foreign matter removal performance without the concern of adhesive residue. [Solution] In one example, the cleaning sheet 1 has a base material 2 and a resin layer 3 provided on the surface of the base material, and a moth-eye structure is formed in the resin layer 3. The water contact angle of the surface on which the moth-eye structure is formed may be 25° or less, or 110° or more, and is not particularly limited.

Description

[Technical Field]

[0001] This invention relates to a cleaning sheet. [Background technology]

[0002] To remove foreign matter adhering to objects to be cleaned, cleaning sheets with an adhesive or bonding functional layer are sometimes used. Generally, the higher the adhesiveness, the better the foreign matter removal performance. However, if the adhesiveness is too high, some of the resin in the functional layer may adhere to the object being cleaned, resulting in contamination of the object. This phenomenon of contamination of the object being cleaned is called "adhesive residue."

[0003] Because it is often difficult to remove functional layers that have adhered due to adhesive residue from the object being cleaned, it is necessary to prevent the occurrence of adhesive residue. In particular, when cleaning the outer surface of rollers of equipment that conveys sheets with rollers, the structure of the equipment makes it extremely difficult to remove adhesive residue, so it is also necessary to eliminate the possibility of adhesive residue occurring. However, if the adhesiveness is too low, the foreign matter removal performance will be poor. Thus, it can be said that there is a trade-off between preventing adhesive residue and achieving good foreign matter removal performance.

[0004] To simultaneously prevent adhesive residue and achieve good foreign matter removal performance, cleaning materials having a functional layer of fibers or an abrasive layer with irregularities have been proposed. However, fibers and abrasive layers may damage the object being cleaned. In addition, debris from the fibers or abrasive layer may contaminate the object being cleaned. Therefore, a cleaning material having a urethane layer on its surface has been proposed as a cleaning material that can prevent adhesive residue and improve foreign matter removal performance (Patent Document 1). [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2011-147884 [Overview of the project]

Problems to be Solved by the Invention

[0006] However, in the cleaning material of Patent Document 1, since the urethane layer exhibits adhesiveness, there is still a concern about glue residue. In addition, since the urethane layer has a relatively low adhesive force, the foreign matter removal performance is also insufficient.

[0007] The present invention provides a cleaning sheet that has excellent foreign matter removal performance despite having no concern about glue residue.

Means for Solving the Problems

[0008] The present invention includes the following embodiments, but is not limited thereto. [1] A cleaning sheet for cleaning the outer peripheral surface of a roller of a device for conveying a sheet with a roller, The cleaning sheet having a fine uneven structure with a moss-eye structure on the surface. [2] Having a base material and a resin layer provided on the surface of the base material, The cleaning sheet according to [1], wherein the moss-eye structure is formed in the resin layer. [3] The cleaning sheet according to [2], wherein the base material contains at least one selected from the group consisting of an acrylic resin, a polycarbonate resin, a polyester resin, and a cellulose resin. [4] The cleaning sheet according to any one of [1] to [3], wherein the water contact angle of the surface on which the moss-eye structure is formed is 25° or less. [5] The cleaning sheet according to any one of [1] to [4], wherein the water contact angle of the surface on which the moss-eye structure is formed is 110° or more. [6] The average distance between adjacent convex portions of the moss-eye structure is 20 to 40 nm, The cleaning sheet according to any one of [1] to [5], wherein the average height of the convex portions of the moss-eye structure is 60 to 800 nm.

Effects of the Invention

[0009] According to the present invention, it is possible to provide a cleaning sheet that is excellent in foreign matter removal performance despite having no concern about paste residue.

Brief Description of the Drawings

[0010] [Figure 1] FIG. 1 is a cross-sectional view schematically showing an example of a cleaning sheet. [Figure 2] FIG. 2 is an explanatory view of an example of a method for manufacturing a mold.

Embodiments for Carrying Out the Invention

[0011] [Explanation of Terms] “(Meth)acrylate” is a general term for acrylate and methacrylate. “Active energy ray ” is a term that includes visible light, ultraviolet rays, electron beams, plasma, heat rays (such as infrared rays), etc. s “Visible light” means light rays with a wavelength of 400 to 780 nm. “~” indicating a numerical range means including the numerical values described before and after it as the lower limit value and the upper limit value. The numerical ranges disclosed in this specification can be combined arbitrarily with the lower limit value and the upper limit value to form a new numerical range.

[0012] Hereinafter, several embodiments will be described with appropriate reference to the drawings. However, the following description relates to representative examples, and the present invention is not limited to the following description. The dimensional ratios in each drawing are for convenience of explanation and are different from the actual ones. In the following drawings, the same components are denoted by the same reference numerals, and the description of overlapping components may be omitted.

[0013] [Cleaning Sheet] The cleaning sheet of the present invention is for cleaning the outer surface of the rollers of a device that transports sheets using rollers. By transporting the sheet while the rollers are rotating and in contact with the cleaning sheet, foreign matter and other substances adhering to the outer surface of the rollers can be attached to the cleaning sheet and removed.

[0014] The cleaning sheet 1 illustrated in Figure 1 has a base material 2 and a resin layer 3 provided on the surface of the base material 2. One or more intermediate layers may be sandwiched between the base material 2 and the resin layer 3 formed on its surface in order to provide adhesion.

[0015] The material of base material 2 is not particularly limited as long as it can conform to the shape of the roller, but examples include acrylic resin, polycarbonate resin, styrene resin, polyester resin, cellulose resin (triacetylcellulose, etc.), polyolefin resin, alicyclic polyolefin resin, polyimide resin, silicone resin, and fluororesin. In terms of conformability to the roller, acrylic resin, polycarbonate resin, polyester resin, and cellulose resin are preferred. The material of base material 2 may be one type, or two or more types may be mixed in any proportion and used in combination.

[0016] The surface of the resin layer 3 has a moth-eye structure, which is a fine uneven structure in which multiple protrusions 4 are arranged at intervals smaller than the wavelength of visible light. It is known that a moth-eye structure is an effective means of anti-reflection because the refractive index increases continuously from the refractive index of air to the refractive index of the material, but in the present invention it is used to adsorb and remove foreign matter adhering to the outer surface of a roller. Because the cleaning sheet of the present invention has a fine uneven structure which is a moth-eye structure on its surface, it has excellent foreign matter removal performance despite the absence of concerns about adhesive residue. Thus, the resin layer is an essential component of the cleaning sheet of the present invention. Therefore, in some other embodiments other than the example in Figure 1, the base material 2 can be omitted, but is not particularly limited.

[0017] The protrusions 4 formed on the surface of the resin layer 3 are preferably those formed by transferring multiple pores (recesses) on the surface of the anodized alumina. The shape of the multiple protrusions 4 is not particularly limited, but examples include a roughly conical shape, a roughly cylindrical shape, a bell shape, and a pyramidal shape. A moth-eye structure is a micro-undulation structure having such multiple protrusions 4 periodically.

[0018] The average spacing (pitch) between the protrusions 4 of the moth-eye structure is less than or equal to the wavelength of visible light, i.e., 400 nm or less, preferably 300 nm or less, more preferably 250 nm or less, and even more preferably 200 nm or less. The average spacing between the protrusions 4 is preferably 20 nm or more, more preferably 80 nm or more, even more preferably 100 nm or more, particularly preferably 130 nm or more, and most preferably 140 nm or more, as this facilitates the formation of the protrusions 4 and suppresses the merging of the tips of adjacent protrusions 4 into one. The preferred lower and upper limits of the average spacing between the protrusions 4 can also be arbitrarily combined; for example, 20 to 400 nm is preferred, 130 to 300 nm is more preferred, 130 to 250 nm is even more preferred, and 140 to 200 nm is particularly preferred.

[0019] The average spacing between the protrusions 4 is obtained by observing a cross-section of the resin layer 3 cut in the thickness direction with an electron microscope, measuring the distance w (the distance from the center of one protrusion 4 to the center of the next) between adjacent protrusions 4 at 10 arbitrary points, and averaging these measurements.

[0020] The average height of the protrusions 4 in the moth-eye structure is preferably 60 to 800 nm, more preferably 100 to 700 nm, even more preferably 150 to 600 nm, and particularly preferably 200 to 500 nm. If the average height of the protrusions 4 in the moth-eye structure is above the lower limit of the above numerical range, the foreign matter removal performance when used as a cleaning sheet is further improved. If the average height of the protrusions 4 in the moth-eye structure is below the upper limit of the above numerical range, the protrusions are easier to form. The average height of the protrusion 4 is the average of the vertical distance h between the highest point of the protrusion 4 and the lowest point of the adjacent recess 5, measured at 10 arbitrary points by observing the cross-section of the resin layer 3 cut in the thickness direction with an electron microscope.

[0021] The aspect ratio of the protrusions (average height of the protrusions / average distance between adjacent protrusions) is preferably 1 to 8, more preferably 1.5 to 6, and even more preferably 2 to 4. If the aspect ratio of the protrusions is above the lower limit of the above numerical range, the foreign matter removal performance when used as a cleaning sheet is further improved. If the aspect ratio of the protrusions is below the upper limit of the above numerical range, the protrusions are easier to form.

[0022] When a moth-eye structure with fine irregularities is formed from a hydrophilic material, the surface of the moth-eye structure can exhibit superhydrophilicity. In the case of hydrophilic materials, the water contact angle of the surface on which the moth-eye structure is formed is preferably 25° or less, more preferably 20° or less, and even more preferably 15° or less. When the water contact angle of the surface of the resin layer 3 is below the above upper limit, the adsorption of foreign substances containing moisture, polar foreign substances, and hydrophobic foreign substances such as oil is improved, and the foreign substance removal performance is further enhanced. Furthermore, even when water adheres to the surface, it does not form droplets but spreads out, preventing fogging and exhibiting anti-fogging properties. The lower limit of the water contact angle of the surface of the resin layer 3 using a hydrophilic material is not particularly limited, but may be, for example, 3°. Hydrophilic materials will be described later.

[0023] The moth-eye structure, which is a fine uneven structure, may be formed from a hydrophobic material. In the case of a hydrophobic material, the water contact angle of the surface on which the moth-eye structure is formed is preferably 110° or more, more preferably 120° or more, and even more preferably 130° or more. If the water contact angle of the surface of the resin layer 3 is above the lower limit, water does not adhere easily and water droplets do not form, so fogging does not occur and anti-fogging properties are exhibited. The upper limit of the water contact angle on the surface of the resin layer 3 using a hydrophobic material is not particularly limited, but it may be, for example, 140°. Hydrophobic materials will be described later.

[0024] The resin layer 3 is preferably a layer of cured product of an active energy ray-curable composition. The active energy ray-curable composition preferably contains a polymerizable compound and a polymerization initiator.

[0025] Examples of polymerizable compounds include monomers, oligomers, and reactive polymers having at least one of a radical polymerizable bond and a cationic polymerizable bond in their molecules. The active energy ray curable composition may contain a non-reactive polymer and an active energy ray sol-gel reactive composition.

[0026] Examples of monomers having radical polymerizable bonds in their molecules include monofunctional monomers and polyfunctional monomers. Examples of monofunctional monomers include methyl (meth)acrylate, ethyl (meth)acrylate, propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, s-butyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, lauryl (meth)acrylate, alkyl (meth)acrylate, tridecyl (meth)acrylate, stearyl (meth)acrylate, cyclohexyl (meth)acrylate, benzyl (meth)acrylate, phenoxyethyl (meth)acrylate, isobornyl (meth)acrylate, glycidyl (meth)acrylate. Examples include (meth)acrylate derivatives such as (meth)acrylate, tetrahydrofurfuryl (meth)acrylate, allyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, and 2-ethoxyethyl (meth)acrylate; (meth)acrylic acid and (meth)acrylonitrile; styrene derivatives such as styrene and α-methylstyrene; and (meth)acrylamide derivatives such as (meth)acrylamide, N-dimethyl (meth)acrylamide, N-diethyl (meth)acrylamide, and dimethylaminopropyl (meth)acrylamide. Monofunctional monomers may be used individually or in combination of two or more.

[0027] Examples of polyfunctional monomers include ethylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, isocyanuric acid ethylene oxide-modified di(meth)acrylate, triethylene glycol di(meth)acrylate, diethylene glycol di(meth)acrylate, neopentyl glycol di(meth)acrylate, 1,6-hexanediol di(meth)acrylate, 1,5-pentanediol di(meth)acrylate, 1,3-butylene glycol di(meth)acrylate, and polyethylene glycol. Di(meth)acrylate, polybutylene glycol di(meth)acrylate, 2,2-bis(4-(meth)acryloxypolyethoxyphenyl)propane, 2,2-bis(4-(meth)acryloxyethoxyphenyl)propane, 2,2-bis(4-(3-(meth)acryloxy-2-hydroxypropoxy)phenyl)propane, 1,2-bis(3-(meth)acryloxy-2-hydroxypropoxy)ethane, 1,4-bis(3-(meth)acryloxy-2-hydroxypropoxy)butane, dimethylol tricyclodecane di(meth)acrylate Difunctional monomers such as tri(meth)acrylate, ethylene oxide adduct of bisphenol A, di(meth)acrylate, propylene oxide adduct of bisphenol A, neopentyl glycol di(meth)acrylate, divinylbenzene, methylenebisacrylamide; pentaerythritol tri(meth)acrylate, trimethylolpropane tri(meth)acrylate, trimethylolpropane ethylene oxide modified tri(meth)acrylate, trimethylolpropane propylene oxide modified tri(meth)acrylate Trifunctional monomers such as acrylates, trimethylolpropane ethylene oxide-modified triacrylates, and isocyanuric acid ethylene oxide-modified tri(meth)acrylates; tetrafunctional or more monomers such as dipentaerythritol hexa(meth)acrylate, dipentaerythritol penta(meth)acrylate, ditrimethylolpropane tetraacrylate, tetramethylolmethane tetra(meth)acrylate, pentaerythritol ethoxytetra(meth)acrylate, and ethylene oxide-modified dipentaerythritol hexaacrylate;Examples include difunctional or more functional urethane acrylates and difunctional or more functional polyester acrylates. Polyfunctional monomers may be used individually or in combination of two or more types.

[0028] Examples of monomers having cationic polymerizable bonds include monomers having epoxy groups, oxetanyl groups, oxazolyl groups, vinyloxy groups, and the like. A single monomer having cationic polymerizable bonds may be used alone, or two or more may be used in combination. Among the monomers having cationic polymerizable bonds, monomers having epoxy groups are particularly preferred.

[0029] Examples of oligomers or reactive polymers include unsaturated polyesters such as condensates of unsaturated dicarboxylic acids and polyhydric alcohols; polyester (meth)acrylate, polyether (meth)acrylate, polyol (meth)acrylate, epoxy (meth)acrylate, urethane (meth)acrylate, cationic epoxy compounds, and single or copolymer polymers of the above monomers having radical polymerizable bonds in their side chains. The oligomer and reactive polymer may be used individually or in combination of two or more types.

[0030] Examples of non-reactive polymers include acrylic resins, styrene resins, polyurethanes, cellulose resins, polyvinyl butyral, polyesters, and thermoplastic elastomers. A single non-reactive polymer may be used, or two or more may be used in combination.

[0031] Examples of active energy ray sol-gel reactive compositions include alkoxysilane compounds and alkyl silicate compounds. The active energy ray sol-gel reactive composition may be used individually or in combination of two or more types.

[0032] Examples of alkoxysilane compounds include the compound shown in formula (1) below. R 1 xSi(OR 2 ) y ···(1) In formula (1), R 1 and R 2 each independently represent an alkyl group having 1 to 10 carbon atoms, and x and y represent integers satisfying the relationship x + y = 4.

[0033] Examples of the alkoxysilane compound include tetramethoxysilane, tetra-i-propoxysilane, tetra-n-propoxysilane, tetra-n-butoxysilane, tetra-sec-butoxysilane, tetra-t-butoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, trimethylethoxysilane, trimethylmethoxysilane, trimethylpropoxysilane, and trimethylbutoxysilane. The alkoxysilane compound may be used alone or in combination of two or more.

[0034] Examples of the alkyl silicate compound include the compound of the following formula (2). R 3 O[Si(OR 5 )(OR 6 )O] z R 4 ···(2) In formula (2), R 3 to R 6 each independently represent an alkyl group having 1 to 5 carbon atoms, and z represents an integer of 3 to 20.

[0035] Examples of the alkyl silicate compound include methyl silicate, ethyl silicate, isopropyl silicate, n-propyl silicate, n-butyl silicate, n-pentyl silicate, and acetyl silicate. The alkyl silicate compound may be used alone or in combination of two or more.

[0036] Examples of active energy ray curable compositions that can form hydrophobic materials include compositions containing at least one of a fluorine-containing compound and a silicone-based compound as polymerizable compounds.

[0037] As the fluorine-containing compound, a compound having a fluoroalkyl group represented by the following formula (3) is preferred. -(CF2) n -X ···(3) In equation (3), X represents a fluorine atom or a hydrogen atom, and n represents an integer of 1 or more. n is preferably 1 to 20, more preferably 3 to 10, and particularly preferably 4 to 8.

[0038] Examples of fluorine-containing compounds include fluorine-containing monomers, fluorine-containing silane coupling agents, fluorine-containing surfactants, and fluorine-containing polymers. Examples of fluorine-containing monomers include fluoroalkyl group-substituted vinyl monomers and fluoroalkyl group-substituted ring-opening polymerizable monomers. Examples of fluoroalkyl group-substituted vinyl monomers include fluoroalkyl group-substituted (meth)acrylates, fluoroalkyl group-substituted (meth)acrylamides, fluoroalkyl group-substituted vinyl ethers, and fluoroalkyl group-substituted styrenes. Examples of fluoroalkyl group-substituted ring-opening polymerizable monomers include fluoroalkyl group-substituted epoxy compounds, fluoroalkyl group-substituted oxetane compounds, and fluoroalkyl group-substituted oxazoline compounds.

[0039] As the fluorine-containing monomer, fluoroalkyl group-substituted (meth)acrylates are preferred, and the compound of the following formula (4) is particularly preferred. CH2=C(R 7 )C(O)O-(CH2) m -(CF2) p -X ···(4) In formula (4), R 7 represents a hydrogen atom or a methyl group, X represents a hydrogen atom or a fluorine atom, m represents an integer from 1 to 6, and p represents an integer from 1 to 20. m is preferably 1 to 3, and more preferably 1 or 2. p is preferably 3 to 10, and more preferably 4 to 8.

[0040] As a fluorine-containing silane coupling agent, a fluoroalkyl group-substituted silane coupling agent is preferred, and the compound of the following formula (5) is particularly preferred. (R f ) a R 8 b SiY c ...(5) In formula (5), R f R represents a fluorine-substituted alkyl group having 1 to 20 carbon atoms, which may contain one or more ether or ester bonds. 8 represents an alkyl group having 1 to 10 carbon atoms, Y represents a hydroxyl group or a hydrolyzable group, and a, b, and c represent integers satisfying a+b+c=4 and a≧1, c≧1.

[0041] R f Examples of such groups include the 3,3,3-trifluoropropyl group, the tridecafluoro-1,1,2,2-tetrahydrooctyl group, the 3-trifluoromethoxypropyl group, and the 3-trifluoroacetoxypropyl group. R 8 Examples include methyl groups, ethyl groups, and cyclohexyl groups.

[0042] Examples of hydrolyzable groups of Y include alkoxy groups, halogen atoms, and R. 9 C(O)O is one example. However, R 9 represents a hydrogen atom or an alkyl group having 1 to 10 carbon atoms. Examples of alkoxy groups include methoxy, ethoxy, propyloxy, i-propyloxy, butoxy, i-butoxy, t-butoxy, pentyloxy, hexyloxy, cyclohexyloxy, heptyloxy, octyloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, 3,7-dimethyloctyloxy, and lauryloxy groups. Examples of halogen atoms include Cl, Br, and I. R 9 Examples of C(O)O include CH3C(O)O and C2H5C(O)O. With respect to a, b, and c, it is preferable that a=1, b=0, and c=3.

[0043] Examples of fluorine-containing silane coupling agents include 3,3,3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriacetoxysilane, dimethyl-3,3,3-trifluoropropylmethoxysilane, and tridecafluoro-1,1,2,2-tetrahydrooctyltriethoxysilane. Fluorine-containing silane coupling agents may be used individually or in combination of two or more types.

[0044] Examples of fluorine-containing surfactants include fluoroalkyl group-containing anionic surfactants and fluoroalkyl group-containing cationic surfactants. Fluorine-containing surfactants may be used individually or in combination of two or more types.

[0045] Examples of fluoroalkyl group-containing anionic surfactants include fluoroalkyl carboxylic acids having 2 to 10 carbon atoms or their metal salts, disodium perfluorooctanesulfonyl glutamate, sodium 3-[omega-fluoroalkyl(C6-C11)oxy]-1-alkyl(C3-C4) sulfonate, sodium 3-[omega-fluoroalkanoyl(C6-C8)-N-ethylamino]-1-propanesulfonate, fluoroalkyl(C11-C20) carboxylic acids or their metal salts, and perfluoroalkyl Examples include fluorocarboxylic acids (C7-C13) or their metal salts, perfluoroalkyl (C4-C12) sulfonic acids or their metal salts, perfluorooctanesulfonic acid diethanolamide, N-propyl-N-(2-hydroxyethyl)perfluorooctanesulfonamide, perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, perfluoroalkyl (C6-C10)-N-ethylsulfonylglycine salt, and monoperfluoroalkyl (C6-C16) ethyl phosphate esters. Fluoroalkyl group-containing anionic surfactants may be used individually or in combination of two or more.

[0046] Examples of fluoroalkyl group-containing cationic surfactants include fluoroalkyl group-containing aliphatic primary, secondary, or tertiary amine acids, aliphatic quaternary ammonium salts such as perfluoroalkyl (C6-C10) sulfonamidopropyltrimethylammonium salt, benzalkonium salts, benzethonium chloride, pyridinium salts, and imidazolinium salts. Fluoroalkyl group-containing cationic surfactants may be used individually or in combination of two or more types.

[0047] Examples of fluorine-containing polymers include polymers of fluoroalkyl group-containing monomers, copolymers of fluoroalkyl group-containing monomers and poly(oxyalkylene) group-containing monomers, and copolymers of fluoroalkyl group-containing monomers and crosslinking reactive group-containing monomers. The fluorine-containing polymer may also be a copolymer with other copolymerizable monomers. The fluorine-containing polymer may be used alone or in combination of two or more types.

[0048] As the fluorine-containing polymer, a copolymer of a fluoroalkyl group-containing monomer and a poly(oxyalkylene) group-containing monomer is preferred. The poly(oxyalkylene) group is preferably the group represented by the following formula (6). -(OR 10 ) q - ···(6) In formula (6), R 10 represents an alkylene group with 2 to 4 carbon atoms, and q represents an integer greater than or equal to 2.

[0049] R 10 Examples include -CH2CH2-, -CH2CH2CH2-, -CH(CH3)CH2-, and -CH(CH3)CH(CH3)-. A poly(oxyalkylene) group is an identical oxyalkylene unit (OR 10 ) may consist of two or more oxyalkylene units (OR 10 ) may consist of two or more oxyalkylene units (OR 10 The array of ) may be a block or random.

[0050] Examples of silicone compounds include (meth)acrylic acid-modified silicones, silicone resins, and silicone-based silane coupling agents. One silicone compound may be used alone, or two or more may be used in combination. Examples of (meth)acrylic acid-modified silicones include silicone (di)(meth)acrylate.

[0051] As an active energy ray curable composition capable of forming a hydrophilic material, a composition containing 20% ​​by mass or more of tetrafunctional or polyfunctional (meth)acrylate and / or urethane (meth)acrylate, 20% by mass or more of bifunctional or hydrophilic (meth)acrylate and / or urethane (meth)acrylate, and 0% by mass or more and 20% by mass or less of monofunctional monomers, based on the total mass of polymerizable compounds, is preferred.

[0052] Examples of polyfunctional (meth)acrylates and urethane (meth)acrylates with four or more functions include ditrimethylolpropanetetra(meth)acrylate, pentaerythritoltetra(meth)acrylate, pentaerythritol ethoxytetra(meth)acrylate, dipentaerythritol hydroxypenta(meth)acrylate, dipentaerythritol hexa(meth)acrylate, ethylene oxide-modified dipentaerythritol hexaacrylate, and urethane acrylates (manufactured by Daicel-Cytec: EBECRYL220, EBECRYL1290, EBECRYL1290K). Examples include EBECRYL5129, EBECRYL8210, EBECRYL8301, KRM8200), polyether acrylates (manufactured by Daicel-Scytec: EBECRYL81), modified epoxy acrylates (manufactured by Daicel-Scytec: EBECRYL3416), and polyester acrylates (manufactured by Daicel-Scytec: EBECRYL450, EBECRYL657, EBECRYL800, EBECRYL810, EBECRYL811, EBECRYL812, EBECRYL1830, EBECRYL845, EBECRYL846, EBECRYL1870). Polyfunctional (meth)acrylates with four or more functions and urethane (meth)acrylates may be used individually or in combination of two or more.

[0053] The proportion of tetrafunctional or more polyfunctional (meth)acrylate and / or urethane (meth)acrylate is preferably 20% by mass or more relative to the total mass of the polymerizable compound. From the viewpoint of water resistance and chemical resistance, 50% by mass or more is more preferable, and 70% by mass or more is particularly preferable. If the proportion of tetrafunctional or more polyfunctional (meth)acrylate and / or urethane (meth)acrylate is above the above lower limit, the elastic modulus of the resin layer 3 becomes higher, making it easier to suppress coalescence.

[0054] Examples of bifunctional or more hydrophilic (meth)acrylates and urethane (meth)acrylates include (meth)acrylates having long-chain polyethylene glycol such as Aronics M-240, Aronics M260 (manufactured by Toagosei Co., Ltd.), NK Ester AT-20E, and NK Ester ATM-35E (manufactured by Shin Nakamura Chemical Co., Ltd.), polyethylene glycol dimethacrylate, and ethylene oxide-modified dipentaerythritol hexaacrylate. Hydrophilic (meth)acrylates with two or more functionalities may be used individually or in combination of two or more types.

[0055] In a (meth)acrylate having long-chain polyethylene glycol, the total average repeating units of the polyethylene glycol chain present in one molecule is preferably 6 or more, more preferably 9 or more, even more preferably 12 or more, preferably 40 or less, more preferably 30 or less, and even more preferably 20 or less. If the average repeating units of the polyethylene glycol chain are above the lower limit, sufficient hydrophilicity is achieved, and the foreign matter removal performance is improved. If the average repeating units of the polyethylene glycol chain are below the upper limit, compatibility with polyfunctional (meth)acrylates with four or more functions is good, and the active energy ray curable composition is less likely to separate. The preferred lower and upper limits for the average repeating units of the polyethylene glycol chain can be any combination, for example, 6 to 40 is preferred, 9 to 30 is more preferred, and 12 to 20 is particularly preferred.

[0056] The proportion of bifunctional or higher hydrophilic (meth)acrylate and / or urethane (meth)acrylate is preferably 20% by mass or more, and more preferably 40% by mass or more, based on the total mass of the polymerizable compound. If the proportion of bifunctional or higher hydrophilic (meth)acrylate and / or urethane (meth)acrylate is above the aforementioned lower limit, the hydrophilicity will be sufficient, and the foreign matter removal performance will be improved.

[0057] Hydrophilic monofunctional monomers are preferred as monofunctional monomers. Examples of hydrophilic monofunctional monomers include monofunctional (meth)acrylates having polyethylene glycol chains in the ester group, such as M-20G, M-90G, and M-230G (manufactured by Shin-Nakamura Chemical Co., Ltd.), monofunctional (meth)acrylates having hydroxyl groups in the ester group, such as hydroxyalkyl (meth)acrylates, monofunctional acrylamides, and cationic monomers such as methacrylamidopropyltrimethylammonium methyl sulfate and methacryloyloxyethyltrimethylammonium methyl sulfate. As monofunctional monomers, viscosity modifiers such as acryloylmorpholine and vinylpyrrolidone, and adhesion enhancers such as acryloyl isocyanates that improve adhesion to the substrate may be used. Monofunctional monomers may be used individually or in combination of two or more.

[0058] The proportion of monofunctional monomers may be 0% by mass, preferably 5% or more by mass, preferably 20% or less by mass, and more preferably 15% or less by mass, relative to the total mass of the polymerizable compound. By using monofunctional monomers, the adhesion between the substrate and the cured resin is improved. If the proportion of monofunctional monomers is 20% by mass or less, sufficient foreign matter removal performance and scratch resistance are achieved without a shortage of tetrafunctional or polyfunctional (meth)acrylate or bifunctional or hydrophilic (meth)acrylate. The preferred lower and upper limits of the proportion of monofunctional monomers can also be arbitrarily combined; for example, 0% by mass or more and 20% by mass or less is preferred, and 5% by mass or more and 15% by mass or less is preferred.

[0059] Monofunctional monomers may be incorporated into the active energy ray curable composition in an amount of 0 to 35% by mass as low-degree-of-polymerization polymers obtained by (co)polymerizing one or more types of monomers. Examples of low-degree-of-polymer polymers include 40 / 60 copolymer oligomers (MRC Unitech, MG Polymer) of monofunctional (meth)acrylates having polyethylene glycol chains in the ester group, such as M-230G (manufactured by Shin-Nakamura Chemical Co., Ltd.), and methacrylamidopropyltrimethylammonium methyl sulfate.

[0060] When using a photocuring reaction, examples of photopolymerization initiators include carbonyl compounds such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, benzyl, benzophenone, p-methoxybenzophenone, 2,2-diethoxyacetophenone, α,α-dimethoxy-α-phenylacetophenone, methylphenylglyoxylate, ethylphenylglyoxylate, 4,4'-bis(dimethylamino)benzophenone, and 2-hydroxy-2-methyl-1-phenylpropan-1-one; sulfur compounds such as tetramethylthiuram monosulfide and tetramethylthiuram disulfide; and 2,4,6-trimethylbenzoyldiphenylphosphine oxide and benzoyldiethoxyphosphine oxide. The photopolymerization initiator may be used alone or in combination of two or more types.

[0061] When using electron beam curing reactions, polymerization initiators include, for example, thioxanthones such as benzophenone, 4,4-bis(diethylamino)benzophenone, 2,4,6-trimethylbenzophenone, methylorthobenzoylbenzoate, 4-phenylbenzophenone, t-butylanthraquinone, 2-ethylanthraquinone, 2,4-diethylthioxanthone, isopropylthioxanthone, and 2,4-dichlorothioxanthone; diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, benzyldimethyl ketal, 1-hydroxycyclohexyl-phenyl ketone, and 2-methyl-2-morpholino(4-thiomethylphenyl)propan-1-one. Examples include acetophenones such as pan-1-one and 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butanone; benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, and benzoin isobutyl ether; acylphosphine oxides such as 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide, and bis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide; and methylbenzoyl formate, 1,7-bisacridinylheptane, and 9-phenylacridine. Polymerization initiators may be used individually or in combination of two or more.

[0062] When using a thermosetting reaction, examples of thermal polymerization initiators include organic peroxides such as methyl ethyl ketone peroxide, benzoyl peroxide, dicumyl peroxide, t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyoctoate, t-butyl peroxybenzoate, and lauroyl peroxide; azo compounds such as azobisisobutyronitrile; and redox polymerization initiators that combine the above organic peroxides with amines such as N,N-dimethylaniline and N,N-dimethyl-p-toluidine. A single thermal polymerization initiator may be used alone, or two or more may be used in combination.

[0063] The amount of polymerization initiator used is preferably 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of polymerizable compound. If the amount of polymerization initiator used is above the lower limit, polymerization proceeds easily. If the amount of polymerization initiator used is below the upper limit, the resin layer 3 is less likely to be discolored and its mechanical strength is less likely to decrease.

[0064] The active energy ray curable composition may optionally contain additives such as antistatic agents, release agents, fluorine compounds to improve stain resistance, fine particles, and small amounts of solvent. When the active energy ray curable composition contains, for example, a (poly)oxyalkylene alkyl phosphate compound as a release agent, the release properties between the cured resin layer and the mold are particularly good. Furthermore, because the load during demolding is extremely low, there is less damage to the fine uneven structure, and as a result, the fine uneven structure of the mold can be transferred efficiently and accurately.

[0065] The method for manufacturing the cleaning sheet 1 is not particularly limited, but examples include the following methods A1-A3. Method A1: A method of forming a micro-textured structure directly on the surface of a substrate by performing injection molding or press molding using a mold having an inverted micro-textured structure on its surface. Method A2: A method in which an active energy ray-curable composition is sandwiched between a mold having a reversed structure with fine irregularities and a substrate, the active energy ray-curable composition is cured to form a resin layer 3, and then the resin layer 3 and the mold are separated. Method A3: A method in which an active energy ray-curable composition is sandwiched between a mold having an inverted structure of fine irregularities and a substrate, the fine irregularities of the mold are transferred to the active energy ray-curable composition, the mold is separated, and then the active energy ray-curable composition is cured to form a resin layer 3. Among the methods for manufacturing the micro-textured structure, Method A2 and Method A3 are preferred, with Method A2 being more preferred, because they offer excellent transferability of the micro-textured structure and superior freedom in surface composition.

[0066] For example, a mold having multiple pores (recesses) on its surface corresponding to multiple protrusions 4 is used, a substrate 2 is placed on top of the surface of the mold, and an active energy ray curable composition is supplied between them. Then, an active energy ray is irradiated from the substrate 2 side onto the active energy ray curable composition filling the space between the surface of the mold and the substrate 2, and the active energy ray curable composition is cured to form a resin layer 3 on which the multiple pores (recesses) on the surface of the mold are transferred. After that, a cleaning sheet 1 is obtained by peeling it off the mold.

[0067] Examples of light sources for active energy ray irradiation include high-pressure mercury lamps, metal halide lamps, UV-LED lamps, and electrodeless UV lamps. The irradiation energy of the active energy rays is 100 to 10000 mJ / cm². 2 It is preferable.

[0068] Examples of molds include molds with a reversed micro-textured surface created by lithography, molds with a reversed micro-textured surface created by laser processing, molds with a reversed micro-textured surface created by etching a master plate covered with glassy carbon or polyimide with oxygen plasma, molds with anodized porous alumina having multiple pores formed on the surface, and replica molds duplicated from a mother mold with a micro-textured structure by electroforming or the like. Among these molds, molds with anodized porous alumina having multiple pores formed on the surface are preferred because they have excellent anti-reflective properties and are easy to form over a large area of ​​micro-textured structure at low cost. Examples of mold shapes include flat plates, belts, and rolls. Among these mold shapes, belts and rolls are preferred because they allow for the continuous transfer of fine uneven structures and offer excellent productivity.

[0069] As for the mold, a roll-shaped mold with multiple recesses formed on its outer surface is particularly preferred. Roll-shaped molds allow for the creation of large-area cleaning sheets, and the molds are also easy to manufacture. As for the roll-shaped mold, a mold having anodized aluminum on its outer surface is preferred. Alumina anodized is a porous oxide film (anodized aluminum) of aluminum, with multiple pores (recesses) on its surface.

[0070] A method for manufacturing a mold having anodized alumina on its surface includes, for example, the following steps (a) to (e). (a) An oxide film is formed by anodic oxidation of the aluminum substrate in an electrolyte under a constant voltage. (b) Remove the oxide film to create pore generation sites for anodic oxidation. (c) The aluminum substrate is anodized again in an electrolyte to form an oxide film having pores at the pore generation points. (d) Enlarge the diameter of the pores. (e) Repeat steps (c) and (d).

[0071] As shown in Figure 2(a), in step (a), the surface of the aluminum substrate 34 is immersed in an electrolyte solution and anodized under a constant voltage. This forms an oxide film 38 having pores 36 on the surface of the aluminum substrate 34. To prevent "burning" due to excessive current flow, it is preferable to apply a voltage lower than the constant voltage in advance, or to alternately apply and stop the voltage. Since pores 36 with excellent regularity are easily formed, the purity of the aluminum substrate 34 is preferably 99% or higher, more preferably 99.5% or higher, and particularly preferably 99.8% or higher. Examples of electrolytes include oxalic acid, malonic acid, and sulfuric acid.

[0072] When using oxalic acid or malonic acid as the electrolyte, the concentration of oxalic acid or malonic acid is preferably 0.7 M or less. This prevents the current value from becoming too high and the surface of the oxide film 38 from becoming rough. The voltage during anodizing is preferably 20V to 200V, more preferably 40V to 150V, and particularly preferably 60V to 100V. Within the above numerical range, the higher the voltage, the wider the period (pitch) of the pores 36 tends to become, and the deeper the pores 36 tend to become. The electrolyte temperature is preferably 5°C or higher, more preferably 10°C or higher, preferably 45°C or lower, and more preferably 30°C or lower. If the electrolyte temperature is below the above upper limit, the phenomenon known as "burning" is less likely to occur, and pores 36 with excellent regularity are more likely to be formed.

[0073] When sulfuric acid is used as the electrolyte, the concentration of sulfuric acid is preferably 0.7 M or less. If the concentration of sulfuric acid is below the upper limit, the current value will not become too high, making it easier to maintain a constant voltage. The voltage during anodizing is preferably 20V to 100V, and more preferably 60V to 90V. Within the above numerical range, the higher the voltage, the wider the period (pitch) of the pores 36 tends to become, and the deeper the pores 36 tend to become. The electrolyte temperature is preferably 5°C or higher, more preferably 10°C or higher, preferably 30°C or lower, and more preferably 20°C or lower. If the electrolyte temperature is below the above upper limit, the phenomenon known as "burning" is less likely to occur, and pores 36 with excellent regularity are more likely to be formed.

[0074] As shown in Figure 2(b), in step (b), the oxide film 38 is removed to form pore generation points 40 for anodic oxidation. One method for removing the oxide film is to dissolve the aluminum in a solution that selectively dissolves the oxide film without dissolving the aluminum itself. An example of such a solution is a mixture of chromic acid and phosphoric acid. Steps (a) and (b) are preferably performed as appropriate to improve the regularity of the pore arrangement, and are steps that can be omitted in order to shorten the process.

[0075] As shown in Figure 2(c), in step (c), the aluminum substrate 34 from which the oxide film 38 has been removed is immersed again in the electrolyte and anodized under a constant voltage to form an oxide film 38 having cylindrical pores 36. The anodizing in step (c) can be carried out under the same conditions as in step (a). The longer the anodizing time, the deeper the pores that can be formed.

[0076] As shown in Figure 2(d), in step (d), the oxide film 38 is immersed in a solution that dissolves it to enlarge the diameter of the pores 36 obtained by anodic oxidation. Examples of solutions for dissolving the oxide film 38 include a phosphoric acid aqueous solution of about 5% by mass. The longer the processing time for enlarging the diameter of the pores 36, the larger the pore diameter becomes.

[0077] In step (e), steps (c) and (d) described above are repeated. As shown in Figure 2, by repeating the anodizing in step (c) and the pore diameter enlargement process in step (d), anodized alumina having pores 36 with a shape in which the diameter continuously decreases in the depth direction from the opening is formed. As a result, a mold 22 is obtained in which anodized alumina having multiple pores 36 is formed on the surface. The total number of repetitions of steps (c) and (d) is preferably three or more, and more preferably five or more. If steps (a) and (b) are omitted, a mold 22 is obtained in which anodized alumina having multiple pores 36 on its surface is formed by repeating steps (c) and (d).

[0078] The surface of the anodized alumina may be treated with a release agent to facilitate separation from the resin layer 3. Examples of treatment methods include coating with the exemplified release agent or vapor deposition. Examples of release agents that can be used include various waxes such as polyethylene wax and paraffin wax, higher fatty acid alcohols, organopolysiloxanes, anionic surfactants, cationic surfactants, amphoteric surfactants, nonionic surfactants, fluorinated surfactants, organic carboxylic acids and their derivatives, fluorinated resins, silicone resins, and the like. Among these release agents, (poly)oxyalkylene alkyl phosphate compounds are preferred because they exhibit excellent release properties between the cured product of the active energy ray curable composition and the mold surface.

[0079] The shape of the pore 36 is not particularly limited, but examples include a roughly conical shape, a roughly cylindrical shape, a bell shape, and a pyramidal shape. The average period between the 36 pores is less than or equal to the wavelength of visible light, i.e., less than 400 nm.

[0080] The depth of the pores 36 is preferably 60 nm or more, more preferably 100 nm or more, even more preferably 150 nm or more, and particularly preferably 200 nm or more. It is also preferably 800 nm or less, more preferably 700 nm or less, even more preferably 600 nm or less, and particularly preferably 500 nm or less. The preferred lower and upper limits for the depth of the pores 36 can be arbitrarily combined, for example, 60 to 800 nm is preferred, 100 to 700 nm is preferred, 150 to 600 nm is even more preferred, and 200 to 500 nm is particularly preferred. [Examples]

[0081] The embodiments will be described in more detail below with reference to examples, but the present invention is not limited to the following description.

[0082] [Mold making] A cylindrical aluminum substrate, free of rolling marks, was cut from a 99.99% pure aluminum ingot to an outer diameter of 200 mm, an inner diameter of 155 mm, and a length of 350 mm. After being subjected to a cloth polishing treatment, it was electropolished in a perchloric acid / ethanol mixed solution (volume ratio = 1 / 4) to achieve a mirror finish. The obtained aluminum substrate was anodized in a 0.3 M oxalic acid aqueous solution under conditions of 40 V DC and 16°C for 10 minutes. Subsequently, the aluminum substrate was immersed in a 6% by mass phosphoric acid / 1.8% by mass chromic acid mixed aqueous solution to remove the oxide film. The obtained aluminum substrate was anodized in a 0.3 M oxalic acid aqueous solution under conditions of DC 40 V and temperature 16°C for 30 seconds. The aluminum substrate on which the oxide film was formed was immersed in a 5% by mass aqueous phosphoric acid solution at 30°C for 8 minutes to enlarge the pore size (pore size enlargement process). Subsequently, the aluminum substrate was anodized in a 0.3M aqueous oxalic acid solution under conditions of 40V DC and 16°C for 30 seconds (oxide film growth process). This pore size enlargement process and oxide film growth process were repeated a total of four times, and finally the pore size enlargement process was performed again to obtain a roll-shaped mold on which anodized alumina had approximately conical pores with an average spacing of 100 nm and a depth of 200 nm formed on the surface.

[0083] [Preparation of Activated Energy Ray Curable Compositions] (Activated energy ray curable composition 1 for forming hydrophilic materials) 25 parts by mass of dipentaerythritol hexaacrylate, 25 parts by mass of pentaerythritol triacrylate, 25 parts by mass of polyethylene glycol diacrylate, and 25 parts by mass of an ethylene oxide-modified compound of dipentaerythritol hexaacrylate were mixed. Furthermore, 1.5 parts by mass of a photopolymerization initiator and 0.1 parts by mass of a mold release agent were added and mixed to prepare an active energy ray-curable composition 1 for forming a hydrophilic material.

[0084] (Activated energy ray curable composition for forming hydrophobic materials 2) 45 parts by mass of polyfunctional (meth)acrylate (pentaerythritol triacrylate), 45 parts by mass of 1,6-hexanediol diacrylate, and 10 parts by mass of radical polymerizable silicone oil (Shin-Etsu Chemical Co., Ltd., X-22-1602) were mixed. Furthermore, 3.2 parts by mass of a photopolymerization initiator and 0.1 parts by mass of a mold release agent were added and mixed to prepare an active energy ray curable composition 2 for forming a hydrophobic material.

[0085] [Example 1] As described above, the roll-shaped mold was rotated, and a polyethylene terephthalate substrate (product name "Cosmoshine A4300", manufactured by Toyobo Co., Ltd., 75 μm thick) was run along the outer surface of the mold in the direction of the mold's rotation. Active energy ray curable composition 1 was supplied between the outer surface of the mold and the running substrate, and ultraviolet light was irradiated to cure the active energy ray curable composition. The resulting cured material was peeled off the mold to produce a cleaning sheet 1 having a fine uneven structure that is a hydrophilic moth-eye structure.

[0086] [Example 2] A cleaning sheet 2 having a hydrophobic moth-eye structure with fine irregularities was manufactured under the same conditions as in Example 1, except that active energy ray curable composition 2 was used instead of active energy ray curable composition 1.

[0087] [Comparative Example 1] I purchased a commercially available PET film (Cosmoshine A-4300, manufactured by Toyobo Co., Ltd.). This PET film was used as the cleaning sheet in Comparative Example 1.

[0088] [Comparative Example 2] A cleaning sheet 3 without a moth-eye structure (a fine uneven surface) was manufactured under the same conditions as in Example 1, except that a roll-shaped mold with a mirror-like surface was used instead of the roll-shaped mold used in Example 1.

[0089] [Evaluation Method] The evaluation results are shown in Table 1.

[0090] (180° peel strength) Test specimens were prepared by cutting the cleaning sheets for each example to a width of 25 mm and a length of 350-400 mm. The glass plate (soda glass, 50 mm x 150 mm x 3 mm thick) used as the substrate was washed with a neutral detergent, rinsed thoroughly with deionized water, dried, and then the surface was wiped with a Bencot (Asahi Kasei, model number: PS-2) soaked in ethanol. After drying, it was used as the test plate. The resin layer of the above test specimen was pressed onto the test plate using a 2 kg pressure roller (IMADA, model number: APR-97-2K) at a pressure speed of 5 mm / s for two passes. After that, it was left to stand for 24 hours in an atmosphere of 23°C and 50% RH. The loose portion of the test specimen was folded back 180°, and a 30mm section was peeled off. The test plate was then secured to the lower chuck of the peel strength tester and the end of the test specimen to the upper chuck at room temperature. The cleaning material was then peeled off the substrate at a peel angle of 180° and a speed of 300mm / min, and the adhesive strength was measured.

[0091] (water contact angle) A cleaning sheet was attached to one side of a microscope slide (product name "S9112", manufactured by Matsunami Glass Industry Co., Ltd.) via an adhesive layer. At this time, the side of the cleaning sheet opposite to the side with the resin layer was facing the microscope slide when the cleaning sheet and microscope slide were attached. Then, using a contact angle meter (Kyowa Interface Chemical Co., Ltd., "DM-501"), distilled water was placed in a plastic syringe and dropped onto the surface with the resin layer from a 22G stainless steel needle attached to the tip of the plastic syringe (amount of water dropped: 1 μL, temperature: 25°C). The contact angle was measured at 10 arbitrary locations on the surface with the resin layer 7 seconds after the water was dropped. The average value of the 10 locations was taken as the water contact angle.

[0092] (Foreign matter removal) Double-sided tape (product name "Nicetack", manufactured by Nichiban, model number: NWBB-20) was cut to 20mm x 20mm. The cut double-sided tape was attached to one point on the roller of a pressure roller (manufactured by Imada, model number: APR-97-2K, diameter 97mm, circumference 305mm). Then, the pressure roller was brought into contact with a cleaning sheet placed on a flat surface. Next, the pressure roller was rolled 5m on the cleaning sheet at a speed of approximately 0.1m / s to remove the double-sided tape that had adhered to the cleaning sheet. After that, the percentage of double-sided tape removed from the pressure roller by the cleaning sheet was evaluated according to the following criteria. Excellent: Over 90% of the double-sided tape area was transferred from the pressure roller to the cleaning sheet. Good: The area of ​​double-sided tape transferred from the pressure roller to the cleaning sheet is between 50% and 90%. Unacceptable: The area of ​​double-sided tape transferred from the pressure roller to the cleaning sheet is less than 50%.

[0093] (Glue residue) A crimping roller (manufactured by Imada, model number: APR-97-2K, diameter 97mm, circumference 305mm) was brought into contact with a cleaning sheet placed on a flat surface. The crimping roller was then rolled 5m across the cleaning sheet at a speed of approximately 0.1m / s. Afterward, the surface of the crimping roller was visually inspected to determine if any adhesive had adhered to it. Excellent: No adhesive is present on the surface of the pressure roller. Unacceptable: Adhesive has adhered to the surface of the pressure roller.

[0094] [Table 1]

[0095] In Examples 1 and 2, the cleaning sheets having a moth-eye structure on their surface demonstrated excellent foreign matter removal performance, and no adhesive residue was left behind. Since the cleaning sheets in Examples 1 and 2 exhibit no tackiness or adhesion, with a 180° peel strength of 0N, the possibility of adhesive residue being left behind can be eliminated, and it can be said that there is no concern about adhesive residue. In contrast, in Comparative Examples 1 and 2, cleaning sheets that did not have a moth-eye structure on their surface were used, resulting in insufficient foreign matter removal performance. [Industrial applicability]

[0096] According to the present invention, it is possible to provide a cleaning sheet that has excellent foreign matter removal performance despite the absence of concerns about adhesive residue. [Explanation of Symbols]

[0097] 1 Cleaning sheet 2 Base material 3. Resin layer

Claims

1. A cleaning sheet for cleaning the outer surface of the rollers of a device that transports sheets using rollers, A cleaning sheet with a surface featuring a moth-eye structure of fine irregularities.

2. It comprises a base material and a resin layer provided on the surface of the base material, The cleaning sheet according to claim 1, wherein the resin layer has the moth-eye structure formed thereon.

3. The cleaning sheet according to claim 2, wherein the substrate contains at least one selected from the group consisting of acrylic resin, polycarbonate resin, polyester resin, and cellulose resin.

4. The cleaning sheet according to any one of claims 1 to 3, wherein the water contact angle of the surface on which the moth-eye structure is formed is 25° or less.

5. The cleaning sheet according to any one of claims 1 to 3, wherein the water contact angle of the surface on which the moth-eye structure is formed is 110° or more.

6. The average spacing between adjacent protrusions in the aforementioned moth-eye structure is 20 to 400 nm. The cleaning sheet according to any one of claims 1 to 3, wherein the average height of the protrusions of the moth-eye structure is 60 to 800 nm.

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