Antiviral Sheet

Abstract

To provide an antiviral sheet which retains antiviral property for a long time and enables easy adhesion to and peeling from an adherend.SOLUTION: An antiviral sheet comprises a transparent base material, a top coat layer provided on one surface of the transparent base material, and an adhesive layer provided on the other surface of the transparent base material, wherein the top coat layer contains a cured product of a curable resin composition and an antiviral agent, the antiviral agent contains at least one selected from an antiviral agent in which metal ions are carried on a carrier, an antiviral agent containing metal ions in the carrier, particles containing an imidazole compound, particles containing a styrene polymer derivative compound and an unsaturated carboxylic acid derivative compound, and a radioactive compound, and the metal ion is at least one selected from a silver ion, a copper ion and a zinc ion.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an antiviral sheet having an antiviral surface, and in particular to an antiviral sheet having transparency. [Background technology]

[0002] Protective sheets are often attached to the surfaces of displays in office equipment, touch panels, smartphones, and other devices to protect the display. Protective sheets are also sometimes attached to window glass to prevent it from shattering. These protective sheets must be highly transparent so that the text and images displayed on the display, as well as the view on the other side of the window, can be seen.

[0003] Patent Documents 1 and 2 disclose protective sheets having a configuration in which a protective layer made of a thermosetting resin, an ionizing radiation curable resin, or the like is provided on a plastic film. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-30341 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-284158 DISCLOSURE OF THE INVENTION [Problem to be solved by the invention]

[0005] The displays and windows mentioned above are touched by an unspecified number of people and are prone to becoming soiled, so they need to be kept clean by wiping them down. In particular, in situations where influenza viruses and the novel coronavirus (COVID-19) are prevalent, frequent wiping and cleaning using chemicals is required. Therefore, the protective sheets mentioned above are required to have antiviral properties and to have long-lasting antiviral properties. Furthermore, the protective sheets mentioned above also need to be easy to replace. However, no products that meet these requirements have been proposed to date. The present disclosure has been made in consideration of the above-mentioned problems, and has an object to provide an antiviral sheet that has long-lasting antiviral properties and can be easily attached to and removed from an adherend. [Means for solving the problem]

[0006] In order to solve the above problems, the present disclosure provides the following [1] to [9]. [1] An antiviral sheet having a transparent substrate, a top coat layer provided on one surface of the transparent substrate, and a pressure-sensitive adhesive layer provided on the other surface of the transparent substrate, wherein the top coat layer contains a cured product of a curable resin composition and an antiviral agent, wherein the antiviral agent contains at least one selected from an antiviral agent in which a metal ion is supported on a carrier, an antiviral agent in which a metal ion is contained in a carrier, particles containing an imidazole compound, particles containing a styrene polymer derivative compound and an unsaturated carboxylic acid derivative compound, and a radioactive compound, and the metal ion is at least one selected from silver ions, copper ions, and zinc ions. [2] The antiviral sheet according to [1], wherein the content of the antiviral agent in the top coat layer is 0.1 parts by mass or more and 20.0 parts by mass or less per 100 parts by mass of the cured product. [3] The antiviral sheet according to [1] or [2], wherein the antiviral agent is in the form of particles, and the average particle size of the antiviral agent is 0.1 μm or more and 10 μm or less. [4] The antiviral sheet according to [3], wherein D / T is 1.0 or less, where D is the average particle size of the antiviral agent and T is the thickness of the top coat layer. [5] The antiviral sheet according to any one of [1] to [4], wherein at least a portion of the antiviral agent protrudes from the surface of the top coat layer. [6] The antiviral sheet according to any one of [1] to [5], wherein the thickness of the top coat is 1 μm or more and 1000 μm or less. [7] The antiviral sheet according to any one of [1] to [6], wherein the pressure-sensitive adhesive layer has self-adhesive properties. [8] The antiviral sheet according to any one of [1] to [7], which has a total light transmittance according to JIS K7361-1:1997 of 86% or more. [9] The antiviral sheet according to any one of [1] to [8], which has a haze according to JIS K7136:2000 of 20.0% or less. [Effects of the Invention]

[0007] According to the present disclosure, it is possible to obtain an antiviral sheet that has long-lasting antiviral properties and is easy to attach to and peel off from an adherend. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a cross-sectional schematic diagram showing one embodiment of an antiviral sheet according to the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0009] The antiviral sheet of the present disclosure will be described in detail below. In this specification, the expression "AA to BB" indicating a numerical range means "not less than AA and not more than BB."

[0010] [Antiviral sheet] The antiviral sheet of the present disclosure has a transparent substrate, a top coat layer provided on one surface of the transparent substrate, and a pressure-sensitive adhesive layer provided on the other surface of the transparent substrate, wherein the top coat layer comprises a cured product of a curable resin composition and an antiviral agent, wherein the antiviral agent comprises at least one selected from an antiviral agent comprising a carrier carrying a metal ion, an antiviral agent comprising a carrier containing a metal ion, particles containing an imidazole compound, particles containing a styrene polymer derivative compound and an unsaturated carboxylic acid derivative compound, and a radioactive compound, and the metal ion is at least one selected from silver ions, copper ions, and zinc ions.

[0011] When the antiviral sheet of this embodiment exhibits antibacterial and antifungal properties in addition to the antiviral properties, it can also be used as an antibacterial sheet and an antifungal sheet. Generally, even for sheets made of the same material and layer structure, the correlation between their exhibited "antiviral," "antibacterial," and "antifungal" properties may be effective or ineffective depending on the type of virus, bacteria, or mold in question; the environmental conditions; the required level of antiviral, antibacterial, or antifungal properties; etc. For this reason, the antiviral sheet of the present disclosure may be applicable not only to antiviral purposes but also to antibacterial purposes, depending on the type of bacteria, environmental conditions, and the required level of antibacterial properties. Note that, because mold is a type of fungus, the antiviral sheet of the present disclosure may also be applicable to antifungal purposes, depending on the type of mold, environmental conditions, and the required level of antifungal properties.

[0012] In the present disclosure, "antiviral" means that the antiviral activity value measured by the following method is greater than 0.0. The antiviral sheet of the present disclosure preferably has an antiviral activity value of 1.0 or greater, and more preferably 2.0 or greater. The following method is in accordance with ISO21702. <Method for measuring antiviral activity> 0.4 ml of virus solution is dropped onto the topcoat layer side of 5 cm square test pieces (antiviral treated and untreated) and covered with a 4 cm square film. The test pieces are left to stand for 24 hours in an environment of 25°C and 90% RH. After standing, the virus on the test pieces is washed off and recovered, and the virus infectivity is measured. The antiviral activity value is calculated using the following formula (1). R=Ut-At (1) R: Antiviral activity value Ut: Virus infectivity (PFU / cm) after leaving the unprocessed product for 24 hours 2 ) the average of the base 10 logarithms At: Viral infectivity (PFU / cm) of antiviral processed product after leaving it for 24 hours 2 ) the average of the base 10 logarithms

[0013] The antiviral sheet of the present disclosure maintains its antiviral properties even after repeated wiping and cleaning. That is, the antiviral activity value of the antiviral sheet of the present disclosure after a wiping test under the following condition 1 is greater than 0.0. Condition 1 corresponds to a case where the surface of the top coat layer of the antiviral sheet is repeatedly wiped and cleaned with a dry cloth. <Condition 1> Using a white cotton cloth (Kanakin No. 3) for friction, the load was 50g / cm 2 1000 round trips The antiviral activity value after the wipe test under condition 1 is preferably 1.0 or more, and more preferably 2.0 or more.

[0014] The antiviral sheet of the present disclosure has an antiviral activity value greater than 0.0 after a wiping test under the following condition 2. Condition 2 corresponds to a case where the surface of the top coat layer of the antiviral sheet is repeatedly wiped and cleaned with rubbing alcohol. <Condition 2> Using gauze soaked in 70% ethanol, a load of 50g / cm 2 500 round trips The antiviral activity value after the wipe test under condition 2 is preferably 1.0 or more, and more preferably 2.0 or more.

[0015] The antiviral sheet of the present disclosure has an antiviral activity value greater than 0.0 after a wiping test under the following condition 3. Condition 3 corresponds to a case where the surface of the top coat layer of the antiviral sheet is repeatedly wiped and cleaned with water. <Condition 3> Using gauze soaked in pure water, load 50g / cm 2 1000 round trips The antiviral activity value after the wipe test under condition 3 is preferably 1.0 or more, and more preferably 2.0 or more.

[0016] The antiviral sheet of the present disclosure preferably has a total light transmittance according to JIS K7361-1:1997 of 86% or more. With a total light transmittance within the above range, when the antiviral sheet of the present disclosure is attached to an adherend, a viewer can clearly see the adherend. For example, when the adherend is a display, the viewer can clearly see the displayed image, etc. The total light transmittance is more preferably 88% or more, and even more preferably 90% or more.

[0017] The antiviral sheet of the present disclosure preferably has a haze according to JIS K7136:2000 of 20.0% or less. Having a haze within this range allows a viewer to clearly see the adherend when the antiviral sheet of the present disclosure is attached to the adherend. The haze is more preferably 18.0% or less, and even more preferably 15.0% or less.

[0018] In this disclosure, the total light transmittance and haze values ​​refer to the average values ​​of measurements taken at any 20 points on the antiviral sheet.

[0019] The configuration of the antiviral sheet of the present disclosure will be described below with reference to the drawings. Fig. 1 is a cross-sectional schematic diagram showing one embodiment of an antiviral sheet according to the present disclosure. The antiviral sheet 10 in Fig. 1 has a transparent substrate 20, a top coat 30, and a pressure-sensitive adhesive layer 40. The top coat 30 is provided on one surface of the transparent substrate 20. The pressure-sensitive adhesive layer 40 is provided on the surface of the transparent substrate 20 opposite to the surface on which the top coat 30 is provided. A separator 50 may be provided on the surface of the pressure-sensitive adhesive layer 40 opposite to the surface that comes into contact with the transparent substrate 20.

[0020] <Transparent base material> The transparent substrate serves as a support for the top coat layer and the pressure-sensitive adhesive layer. The transparent substrate preferably has high light transmittance. Specifically, the total light transmittance according to JIS K7361-1:1997 is preferably 86% or more.

[0021] The transparent substrate is preferably made of plastic, taking into consideration transparency, light weight, ease of application to an adherend, and the like. The form of the transparent substrate is not particularly limited, but in consideration of ease of application to the adherend, it is preferably a flat plate such as a film or sheet.

[0022] The transparent substrate can be formed from one or more selected from polyolefin resins such as polyethylene and polypropylene; vinyl resins such as polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetate copolymer, and ethylene-vinyl alcohol copolymer; polyester resins such as polyethylene terephthalate, polyethylene naphthalate, and polybutylene terephthalate; acrylic resins such as polymethyl(meth)acrylate and polyethyl(meth)acrylate; styrene resins such as polystyrene; polyamide resins such as nylon 6 and nylon 66; cellulose resins such as triacetyl cellulose; resins such as polycarbonate; polyimide resins; and cycloolefin resins obtained from cycloolefins such as norbornene and dicyclopentadiene. Among these, polyester resins are preferred because of their high light transmittance, excellent heat resistance and moist heat resistance, and rigidity that makes them easy to attach to flat surfaces such as displays. When two or more transparent substrates are used, the substrates are preferably bonded together with a known adhesive.

[0023] The thickness of the transparent substrate is not particularly limited. In consideration of handleability, the thickness of the transparent substrate is preferably 5 μm or more and 400 μm or less, more preferably 10 μm or more and 200 μm or less, and even more preferably 20 μm or more and 150 μm or less. To improve adhesion between the transparent substrate and other layers that come into contact with the transparent substrate, one or both surfaces of the transparent substrate may be subjected to a surface treatment such as a physical surface treatment, such as an oxidation method or a roughening method, or a chemical surface treatment. Examples of oxidation methods include corona discharge treatment, chromium oxidation treatment, flame treatment, hot air treatment, and ozone-ultraviolet treatment, while examples of roughening methods include sandblasting and solvent treatment. These surface treatments are appropriately selected depending on the type of transparent substrate, but corona discharge treatment is generally preferred in terms of the effect of the surface treatment, operability, and the like.

[0024] In order to improve the adhesion between the transparent substrate and a layer that comes into contact with the transparent substrate, an anchor coat layer may be provided on one or both sides of the transparent substrate. The anchor coating layer can be formed by a conventional method using a known anchor coating agent. Examples of anchor coating agents include those containing resins such as polyurethane resin, acrylic resin, melamine resin, polyester resin, phenolic resin, amino resin, and fluororesin. The anchor coating agent may further contain an isocyanate compound for the purpose of improving adhesion and moist heat resistance. The isocyanate compound may be any compound having one or more isocyanate groups in the molecule, and examples include hexamethylene diisocyanate, xylylene diisocyanate, isophorone diisocyanate, and tolylene diisocyanate.

[0025] <Top coat layer> The top coat layer is a layer that exhibits antiviral properties. As shown in Fig. 1, the top coat layer 30 contains a binder resin 31 and an antiviral agent 32. The binder resin 31 contains a cured product of a curable resin composition. The top coat layer may be formed on the entire surface of the transparent substrate, or may be formed on only a part of the surface. The area occupied by the top coat in the surface of the transparent substrate is preferably 80% or more, and more preferably 90% or more.

[0026] To enhance the antiviral properties, it is preferable that at least a portion of the antiviral agent protrudes from the surface of the top coat layer opposite the transparent substrate (hereinafter referred to as the "surface of the top coat layer"), as shown in FIG. 1. The distribution of the antiviral agent in the thickness direction of the top coat layer may be unevenly distributed on the surface of the top coat layer as shown in FIG. 1, or may be dispersed approximately uniformly in the thickness direction of the top coat layer, or may be distributed so that the concentration of the antiviral agent increases from the transparent substrate side toward the surface of the top coat layer. In the in-plane direction of the top coat layer, the antiviral agent is preferably distributed throughout the entire top coat layer. The distribution state in the in-plane direction may be such that the antiviral agent is distributed substantially uniformly, or may be such that there are regions where the antiviral agent is densely concentrated and regions where the antiviral agent is sparsely distributed.

[0027] The thickness of the top coat layer is preferably 1.0 μm or more and 1000 μm or less, taking into consideration processability, scratch resistance, ease of application to an adherend, etc. The thickness of the top coat layer is more preferably 2.0 μm or more and 500 μm or less, even more preferably 3.0 μm or more and 200 μm or less, and particularly preferably 5.0 μm or more and 100 μm or less.

[0028] <Cured Product of Curable Resin Composition> The cured product of the curable resin composition mainly serves as a binder resin that supports the antiviral agent. By including this cured product, the antiviral sheet has good scratch resistance. Furthermore, the antiviral properties can be easily maintained even after repeated wiping and cleaning as described above. In this specification, the "cured product of the curable resin composition" may be abbreviated as "cured product."

[0029] Examples of the cured product of the curable resin composition include a cured product of a thermosetting resin composition or a cured product of an ionizing radiation-curable resin composition, and among these, a cured product of an ionizing radiation-curable resin composition is preferred from the viewpoints of durability of the antiviral activity and production efficiency.

[0030] A thermosetting resin composition is a composition containing at least a thermosetting resin, and is a resin composition that cures when heated. Examples of thermosetting resins include acrylic resins, urethane resins, phenolic resins, urea-melamine resins, epoxy resins, unsaturated polyester resins, and silicone resins. In addition to these thermosetting resins, a curing agent, a curing catalyst, and the like are added to the thermosetting resin composition as needed.

[0031] An ionizing radiation-curable resin composition is a composition containing a compound having an ionizing radiation-curable functional group (hereinafter also referred to as an "ionizing radiation-curable compound"). Representative examples of ionizing radiation-curable resin compositions include electron beam-curable resin compositions and ultraviolet light-curable resin compositions. Among these, electron beam-curable resin compositions are preferred because of their advantages such as high scratch resistance, little odor because no polymerization initiator is required, and resistance to coloration.

[0032] The ionizing radiation-curable functional group is a group that crosslinks and cures upon irradiation with ionizing radiation, and preferred examples thereof include functional groups having an ethylenic double bond such as a (meth)acryloyl group, a vinyl group, and an allyl group. Further examples of the ionizing radiation-curable functional group include an epoxy group and an oxetanyl group. In this specification, the term "(meth)acryloyl group" refers to an acryloyl group or a methcroyl group, and the term "(meth)acrylate" refers to an acrylate or a methacrylate.

[0033] Furthermore, ionizing radiation refers to electromagnetic waves or charged particle beams that have an energy quantum capable of polymerizing or crosslinking molecules. Typically, ultraviolet (UV) rays or electron beams (EB) are used, but it also includes other electromagnetic waves such as X-rays and gamma rays, and charged particle beams such as alpha rays and ion beams.

[0034] Specifically, the ionizing radiation-curable compound can be appropriately selected from polymerizable monomers and polymerizable oligomers (sometimes referred to as "polymerizable prepolymers") that have conventionally been used as ionizing radiation-curable resins. The ionizing radiation-curable compound is preferably a compound having two or more ethylenically unsaturated bond groups, and more preferably a polyfunctional (meth)acrylate compound having two or more ethylenically unsaturated bond groups. Either a monomer or an oligomer can be used as the polyfunctional (meth)acrylate compound. Among these, it is preferable to use an oligomer, considering its excellent mechanical properties, flexibility, suitability for application, and the like. In addition to the oligomer, a monomer can also be added to adjust the viscosity.

[0035] In order to simultaneously achieve good scratch resistance, ease of processing and handling, and antiviral activity in the resulting sheet, the oligomer of a polyfunctional (meth)acrylate compound preferably has a weight-average molecular weight of 1,000 to 10,000, more preferably 2,000 to 6,000. The number of functional groups per oligomer molecule is preferably 2 to 10, more preferably 2 to 6. Among the polyfunctional (meth)acrylate compounds, examples of bifunctional (meth)acrylate monomers include ethylene glycol di(meth)acrylate, bisphenol A tetraethoxydiacrylate, bisphenol A tetrapropoxydiacrylate, and 1,6-hexanediol diacrylate.

[0036] Examples of trifunctional or higher (meth)acrylate monomers include trimethylolpropane tri(meth)acrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipentaerythritol tetra(meth)acrylate, and isocyanuric acid-modified tri(meth)acrylate.

[0037] Examples of polyfunctional (meth)acrylate oligomers include acrylate polymers such as urethane (meth)acrylate, epoxy (meth)acrylate, polyester (meth)acrylate, and polyether (meth)acrylate. Among these, urethane (meth)acrylate oligomers are preferred for reasons such as ensuring coating hardness and toughness. The urethane (meth)acrylate oligomer preferably contains a caprolactone-modified urethane (meth)acrylate oligomer. By including a caprolactone-modified urethane (meth)acrylate oligomer, flexibility can be imparted while ensuring coating hardness and toughness. The proportion of the caprolactone-modified urethane (meth)acrylate oligomer in the urethane (meth)acrylate oligomer is preferably 10% by mass or more and 90% by mass or less, and more preferably 20% by mass or more and 80% by mass or less.

[0038] Urethane (meth)acrylates can be obtained, for example, by reacting a polyhydric alcohol and an organic diisocyanate with a hydroxy (meth)acrylate.

[0039] Preferred epoxy (meth)acrylates are (meth)acrylates obtained by reacting a tri- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with (meth)acrylic acid; (meth)acrylates obtained by reacting a di- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with a polybasic acid and (meth)acrylic acid; and (meth)acrylates obtained by reacting a di- or higher functional aromatic epoxy resin, alicyclic epoxy resin, aliphatic epoxy resin, or the like with a phenol and (meth)acrylic acid.

[0040] The above ionizing radiation curable resins can be used alone or in combination of two or more.

[0041] When the ionizing radiation curable compound is an ultraviolet ray curable compound, the ionizing radiation curable resin composition preferably contains additives such as a photopolymerization initiator and a photopolymerization accelerator. The photopolymerization initiator may be one or more selected from acetophenone, benzophenone, α-hydroxyalkylphenone, Michler's ketone, benzoin, benzil dimethyl ketal, benzoyl benzoate, α-acyloxime ester, thioxanthones, and the like. The photopolymerization accelerator can reduce polymerization inhibition caused by air during curing and increase the curing rate, and examples thereof include one or more selected from p-dimethylaminobenzoic acid isoamyl ester, p-dimethylaminobenzoic acid ethyl ester, etc.

[0042] The content of the cured product of the curable resin composition is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 90% by mass or more, and most preferably 100% by mass, based on the total amount of the binder resin.

[0043] <Antiviral agents> The antiviral agent in the present disclosure includes at least one selected from the following antiviral agents (1) to (5). (1) Antiviral agent carrying metal ions (2) Antiviral agent containing a metal ion as a carrier (3) Particles containing an imidazole compound (4) Particles containing a styrene polymer derivative compound and an unsaturated carboxylic acid derivative compound (5)Radioactive compounds In the antiviral agents (1) and (2), the metal ion is at least one selected from silver ions, copper ions, and zinc ions. In the present disclosure, in consideration of the expression and durability of antiviral activity (hereinafter referred to as "antiviral performance"), the antiviral agent preferably includes at least one selected from (1) an antiviral agent supported by a metal ion, and (2) an antiviral agent comprising a carrier containing a metal ion. In particular, it is preferable that the antiviral agent contains a silver ion as the metal ion. That is, it is particularly preferable that the antiviral agent in the present disclosure includes at least one selected from an antiviral agent supported by a carrier containing a silver ion, and an antiviral agent comprising a carrier containing a silver ion.

[0044] (1) Antiviral agents carrying metal ions, and (2) antiviral agents containing metal ions in a carrier As the carrier, inorganic compounds such as zeolite, apatite, glass, zirconium phosphate, and titanium phosphate are preferred, and porous inorganic compounds are particularly preferred. Zeolites are aluminosilicates of alkali metals or alkaline earth metals, and both natural and synthetic zeolites can be used. Zeolites are classified according to their crystal structure, such as A-type, faujasite type (X-type, Y-type), mordenite type, and clinoptilolite type, and any of these can be used. Apatite is a general term for minerals having a composition represented by the following general formula: M 10(ZO4)3X2 In the above formula, M represents Ca, Ba, Mg, Na, K, Fe, Al, etc., Z represents P, S, Si, As, etc., and X represents F, Cl, O, OH, etc. A representative example that corresponds to the above formula is fluorapatite "Ca 10 (PO4)6F2", hydroxyapatite "Ca 10 (PO4)6(OH)2". Examples of glass include soda glass, borosilicate glass, lead glass, aluminosilicate glass, borate glass, and phosphate glass.

[0045] As a method for supporting or incorporating metal ions into a carrier, various known forms may be appropriately selected taking into consideration various conditions such as the type of curable resin composition, its respective forms, processing conditions, and the required antiviral performance. Here, "containing ions" means that ions or a substance capable of generating ions are held in the carrier in some form. Furthermore, "a substance capable of generating ions" means a substance that generates ions due to external factors or factors over time, such as a substance that generates ions by dissolving in water, etc.

[0046] Specific examples of the supporting or containing form include a method of supporting by physical adsorption or chemical adsorption; a method of supporting by an ion exchange reaction; a method of supporting by a binder; a method of incorporating the metal by implanting a compound containing the metal into the support; and a method of supporting or containing the metal by forming a thin layer of the metal compound on the surface of the support by a thin film formation method such as vapor deposition, dissolution / precipitation reaction, or sputtering.

[0047] The amount of the metal ions in the antiviral agents (1) and (2) above is preferably 0.1 to 30.0 parts by mass, more preferably 0.5 to 25.0 parts by mass, and even more preferably 1.0 to 20.0 parts by mass, relative to 100 parts by mass of the carrier. Here, the "amount of metal ions" refers to both the amount of supported metal ions (silver ions, copper ions, zinc ions) and the amount of contained metal ions (silver ions, copper ions, zinc ions). By setting the amount of metal ions to 0.1 parts by mass or more, the desired antiviral performance can be achieved, while by setting the amount of metal ions to 30.0 parts by mass or less, discoloration due to light can be more easily suppressed.

[0048] The antiviral agents (1) and (2) above are preferably in the form of particles. The shape of the particles of the antiviral agent is not particularly limited, and examples thereof include spheres, ellipsoids, polyhedrons, and scales.

[0049] (3) Imidazole compound particles Imidazole compounds are compounds that contain an imidazole skeleton as a molecular structural unit. In the present disclosure, various imidazole compounds that maintain a particle shape in the top coat layer can be used. Such imidazole compounds are preferably those that are poorly soluble in water and organic solvents, such as methyl benzimidazol-2-ylcarbamate (also known as carbendazim) and polymerized imidazole compounds. However, care must be taken because even methyl benzimidazol-2-ylcarbamate (also known as carbendazim) and polymerized imidazole compounds may dissolve in certain solvents. For example, for methyl benzimidazol-2-ylcarbamate (also known as carbendazim), it is preferable to use methyl ethyl ketone, ethyl acetate, or the like as a solvent.

[0050] The shape of the imidazole compound particles is not particularly limited, and examples thereof include spherical, ellipsoidal, polyhedral, and scale-like shapes.

[0051] (4) Particles containing a styrene polymer derivative compound and an unsaturated carboxylic acid derivative compound In the present disclosure, the "particles comprising a styrene polymer derivative compound and an unsaturated carboxylic acid derivative compound" may be "particles containing a styrene polymer derivative compound and an unsaturated carboxylic acid derivative compound", or may be "mixed particles of particles comprising a styrene polymer derivative compound and particles comprising an unsaturated carboxylic acid derivative compound", or a combination thereof. The constituent components of the styrene polymer derivative compound and the unsaturated carboxylic acid derivative compound preferably have at least one structure selected from the group consisting of styrene, sodium sulfonate, acrylic acid, maleic acid, and fumaric acid, and more preferably have both at least one structure of styrene and sodium sulfonate and at least one structure selected from the group consisting of acrylic acid, maleic acid, and fumaric acid.

[0052] The content ratio of the styrene polymer derivative compound and the unsaturated carboxylic acid derivative compound in the particles is not limited, but the mass ratio is preferably 30:70 to 70:30, and more preferably 40:60 to 60:40. In the case of a mixture of particles (particles A) containing a styrene polymer derivative compound and particles (particles B) containing an unsaturated carboxylic acid derivative compound, the mass ratio of particles A to particles B is preferably 30:70 to 70:30, and more preferably 40:60 to 60:40.

[0053] The reason why particles containing a styrene polymer derivative compound and an unsaturated carboxylic acid derivative compound exhibit antiviral properties is thought to be as follows, although it is not limited to the mechanism speculated below. Influenza viruses invade host cells by binding to sugar chain receptors (the sugar chain ends in neuraminic acid) on the surface of the host cells, but copolymers containing styrene sulfonate have ionic groups similar to neuraminic acid, so they bind to the virus instead of the host cells, capturing the virus and preventing it from binding to the host cell receptor, which is thought to exert an antiviral effect.In addition, unsaturated carboxylic acid derivative compounds generate hydroxyl groups (OH-) when they come into contact with water, and the hydroxyl groups are thought to exert their antiviral effect.

[0054] The shape of the particles (4) above is not particularly limited, and examples thereof include spheres, ellipsoids, polyhedrons, and scales.

[0055] (5)Radioactive compounds In order to prevent adverse health effects caused by radiation, radioactive compounds that emit either or both of α-rays and β-rays, which have a relatively small travel distance in air or a vacuum and a relatively small penetration rate through various materials, are preferred. Furthermore, it is preferable that the radioactive compound emits α-rays and / or β-rays with sufficient energy (quantum) to kill viruses, and emits a small amount of radiation such as γ-rays, which have a high penetration rate through materials.

[0056] Radioactive compounds that emit alpha rays include: 241 Am, 243 Am, 226 Ra, 232 Examples of radioactive compounds that emit β rays include: 147 Pm, 210 Po, 90 Sr, 90 Examples include Y.

[0057] In the present disclosure, the antiviral agent is preferably in the form of particles. When the antiviral agent is in the form of particles, the average particle diameter of the antiviral agent is preferably 0.1 μm or more and 10.0 μm or less, more preferably 0.5 μm or more and 5.0 μm or less, and even more preferably 1.0 μm or more and 4.0 μm or less. By setting the average particle diameter to 0.1 μm or more, the stability of the ink for the top coat layer is easily achieved. Furthermore, by setting the average particle diameter to 10.0 μm or less, it is possible to easily suppress an increase in the haze ratio, poor appearance due to excessive protrusion of the antiviral agent from the surface of the top coat layer, and a decrease in scratch resistance and contamination resistance. Furthermore, it is possible to easily suppress wear of coating device components (such as a coating roll or doctor blade). In this specification, the average particle size refers to the mass average value d50 measured in particle size distribution measurement by laser light diffraction method.

[0058] When the antiviral agent is in the form of particles, when the average particle size of the antiviral agent is defined as D and the thickness of the top coat layer is defined as T, D / T is preferably 1.0 or less, more preferably 0.8 or less, and even more preferably 0.6 or less. Setting D / T to 1.0 or less makes it easier to prevent whitening of the coating film caused by excessive protrusion of the antiviral agent from the surface of the top coat layer, and also makes it easier to prevent wear of coating device components (such as a coating roll or doctor blade). The lower limit of D / T is not particularly limited, but is usually 0.01 or more, and preferably 0.05 or more.

[0059] With regard to the content of the antiviral agent in the top coat layer, relative to 100 parts by mass of the cured product, the lower limit is preferably 0.1 part by mass or more, more preferably 0.5 part by mass or more, and more preferably 1.0 part by mass or more, and the upper limit is preferably 20.0 parts by mass or less, more preferably 17.0 parts by mass or less, more preferably 15.0 parts by mass or less, more preferably 10.0 parts by mass or less, and more preferably 5.0 parts by mass or less. By setting the content of the antiviral agent to 0.1 parts by mass or more, it is possible to achieve the desired antiviral performance. By setting the content of the antiviral agent to 20.0 parts by mass or less, discoloration due to light can be more easily suppressed. Furthermore, by setting the content of the antiviral agent to 20.0 parts by mass or less, the haze of the antiviral sheet can be kept within the above range. Furthermore, deterioration of coating film properties such as coating film strength and scratch resistance can be suppressed. Furthermore, wear of coating device components (coating rolls, doctor blades, etc.) can be more easily suppressed.

[0060] <Other ingredients> The top coat layer may contain additives such as antioxidants, light stabilizers, ultraviolet absorbers, anti-wear agents, and surface conditioners, as long as the effects of the present disclosure are not impaired. Examples of antioxidants include phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and amine-based antioxidants. The content of the antioxidant is preferably 0.1 to 10.0 parts by mass, more preferably 0.5 to 5.0 parts by mass, per 100 parts by mass of the cured product. Examples of the light stabilizer include hindered amine compounds. The content of the light stabilizer is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, and more preferably 1.0 parts by mass or more and 5.0 parts by mass or less, per 100 parts by mass of the cured product. Examples of the ultraviolet absorber include benzotriazole-based ultraviolet absorbers, benzophenone-based ultraviolet absorbers, and triazine-based ultraviolet absorbers, with triazine-based ultraviolet absorbers being preferred. One or more types of ultraviolet absorbers can be used. The content of the ultraviolet absorber is preferably 0.1 parts by mass or more and 20.0 parts by mass or less, and more preferably 0.5 parts by mass or more and 15.0 parts by mass or less, per 100 parts by mass of the cured product. Examples of the anti-wear agent include nanometer-sized particles made of silica, alumina, etc. Specifically, the average particle size (primary particle size) of the anti-wear agent is preferably 10 nm or more, and in consideration of transparency, it is preferably 1000 nm or less. The content of the anti-wear agent is preferably 0.1 to 30.0 parts by mass, more preferably 0.3 to 10.0 parts by mass, per 100 parts by mass of the cured product. Examples of the surface conditioner include silicone-based surface conditioners. The content of the surface conditioner is preferably 0.1 parts by mass or more and 10.0 parts by mass or less, and more preferably 0.3 parts by mass or more and 5.0 parts by mass or less, per 100 parts by mass of the cured product.

[0061] <Adhesive layer> The pressure-sensitive adhesive layer is provided for the purpose of bonding the antiviral sheet to an adherend. In the present disclosure, the pressure-sensitive adhesive layer preferably has self-adhesive properties. Self-adhesive properties refer to the property of quickly adhering to an adherend by its own weight without pressure. In the present disclosure, examples of pressure-sensitive adhesives constituting the pressure-sensitive adhesive layer include silicone resins and urethane resins. The pressure-sensitive adhesive layer may contain a catalyst or the like for curing the pressure-sensitive adhesive, if necessary.

[0062] The thickness of the pressure-sensitive adhesive layer is preferably 3 μm or more and 100 μm or less, and more preferably 10 μm or more and 50 μm or less. A pressure-sensitive adhesive layer thickness of 10 μm or more can improve the adhesive strength with the adherend. On the other hand, a pressure-sensitive adhesive layer thickness of 50 μm or less makes it easier for the total light transmittance and haze ratio of the antiviral sheet to fall within the above-mentioned ranges. Also, the handleability during production and application is improved. Furthermore, when applied to an adherend, it is possible to make it less noticeable that there is a difference in level with the non-adhered portion.

[0063] The pressure-sensitive adhesive layer may contain additives such as a light stabilizer, an ultraviolet absorber, etc. Depending on the application, the light stabilizer and the ultraviolet absorber may be selected from those listed as the light stabilizers and ultraviolet absorbers contained in the top coat layer.

[0064] <Separator> The separator is provided in contact with the pressure-sensitive adhesive layer on the surface of the pressure-sensitive adhesive layer opposite the transparent substrate. The material of the separator is not particularly limited, but plastic films such as PET, paper, etc. can be suitably used. The thickness of the separator is preferably 10 μm or more and 200 μm or less, and more preferably 50 μm or more and 150 μm or less. When the thickness of the separator is within the above range, the workability when peeling off the separator can be improved. The separator may have a surface that has been subjected to a release treatment with a release agent such as a silicone-based release agent.

[0065] [Uses of antiviral sheets] The antiviral sheet of the present disclosure has the advantage that, when attached to an adherend, the adherend can be seen at the attachment location. The location to which the antiviral sheet of the present disclosure is attached is preferably flat. Applications of the antiviral sheet of the present disclosure include the following: (1) Protective sheet for displays or touch panels of office equipment (electronic copiers, printers, etc.). (2) Protective sheets for displays or touch panels of ATM devices used in financial institutions such as banks and post offices. (3) Protective sheets for displays or touch panels of smartphones, tablets, etc. (4) Protective sheet for window glass. (5) A sheet to be placed on furniture such as a desk or shelf. (6) Replacement sheets to be attached to face protection equipment such as goggles and face guards. (7) Protective sheets for in-vehicle displays or in-vehicle touch panels. (8) Protective sheets for in-store advertisements and restaurant menus. (9) Protective sheets for buttons and touch panels on vending machines, self-checkouts, digital signage, etc. (10) Protective sheets for tabletop partitions, etc.

[0066] [Method for manufacturing antiviral sheets] The antiviral sheet of the present disclosure can be produced by the following steps. (1) Formation of the topcoat layer An ink for the top coat layer is prepared. The ink for the top coat layer contains a curable resin composition and an antiviral agent, and optionally contains a solvent and various additives. The ink for the top coat layer is applied to one surface of the transparent substrate by a known method and dried as necessary. The curable resin composition in the ink for the top coat layer is then cured by a method appropriate for the type of resin. This forms a top coat layer on the transparent substrate. (2) Formation of adhesive layer An ink for the adhesive layer is prepared. The ink for the adhesive layer contains an adhesive, and optionally a solvent and various additives. The ink for the adhesive layer is applied to the surface of the transparent substrate opposite to the surface on which the top coat layer is to be formed by a known method, and dried as necessary. Thereafter, a separator is attached to the adhesive layer. Alternatively, the ink for the adhesive layer may be applied to the separator by a known method, dried as necessary, and then laminated onto the surface of the transparent substrate opposite to the surface on which the top coat layer is to be formed. [Example]

[0067] Next, the present disclosure will be described in more detail by way of examples, but the present disclosure is not limited to these examples in any way.

[0068] 1. Evaluation The antiviral sheets of the examples were evaluated as follows: The atmosphere for evaluations 1-2 and 1-3 was a temperature of 23°C ± 5°C and a humidity of 40 to 65% RH.

[0069] 1-1. Antiviral activity value The antiviral activity value of the antiviral sheet of the example was measured according to the "Method for measuring antiviral activity value" in the specification. The antiviral activity value was measured against influenza virus. Measurements were carried out on the samples after the wiping test under each of the following conditions <Condition 1> to <Condition 3>, and on the samples before the test. The results are shown in Table 1. <Condition 1> Using a white cotton cloth (Kanakin No. 3) for friction, the load was 50g / cm 2 1000 round trips <Condition 2> Using gauze soaked in 70% ethanol, a load of 50g / cm 2 500 round trips <Condition 3> Using gauze soaked in pure water, load 50g / cm 2 1000 round trips

[0070] 1-2.Total light transmittance The total light transmittance was measured using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory). Measurements were performed by irradiating measurement light from the separator side. The above measurements were performed at 20 random locations, and the average value was taken as the total light transmittance of the antiviral sheet. The results are shown in Table 1.

[0071] 1-3. Hayes The haze was measured using a haze meter (HM-150, manufactured by Murakami Color Research Laboratory). The measurement included the separator. The above measurement was performed at 20 random locations on the antiviral sheet, and the average value was taken as the haze of the antiviral sheet. The results are shown in Table 1.

[0072] 2. Preparation of antiviral sheets An ink for the top coat layer and an ink for the adhesive layer having the following compositions were prepared. <Ink for topcoat layer> Multifunctional urethane acrylate oligomer 50 parts by mass 50 parts by mass of multifunctional caprolactone-based urethane acrylate oligomer 10 parts by mass of antiviral agent (antiviral agent comprising silver ions supported on a glass carrier, manufactured by Koa Glass Co., Ltd., product number "PG711", average particle size 3.0 μm) Solvent (ethyl acetate) 40 parts by weight <Ink for adhesive layer> 100 parts by weight of silicone resin adhesive (manufactured by Shin-Etsu Chemical Co., Ltd., product name "KR-3704") Platinum catalyst (manufactured by Shin-Etsu Chemical Co., Ltd., product name "CAT-PL-50T") 0.5 parts by mass Solvent (toluene) 100 parts by mass

[0073] The ink for the topcoat layer was roll coated onto one side of a polyethylene terephthalate film (75 μm thick, uncolored) and dried at 60°C for 1 minute. The resin component was then cured by electron beam irradiation to form an 8 μm thick topcoat layer. The electron beam irradiation conditions were 175 keV, 5 Mrad (50 kGy). The ink for the adhesive layer was then applied by gravure printing to the surface of the film opposite to the surface on which the top coat layer was formed, and then dried at 120°C for 1 minute to form an adhesive layer with a thickness of 30 μm. After forming the pressure-sensitive adhesive layer, a PET (thickness: 75 μm) was laminated as a separator to obtain an antiviral sheet of this example.

[0074] 3.Results The evaluation results are shown in Table 1.

[0075] [Table 1]

[0076] The antiviral sheets of the examples had a total light transmittance of 86% or more and a haze of 20.0 or less, and were highly transparent. The antiviral sheets of the examples were confirmed to have high antiviral properties before wiping and to be immediately effective. Furthermore, they were confirmed to have high and sustained antiviral properties even after various wiping tests. The separator of the antiviral sheet of the example was peeled off to check its attachability to a glass plate. It was confirmed that the sheet could be easily attached and peeled off from the glass plate. [Explanation of symbols]

[0077] 10 Antiviral Sheets 20 Transparent base material 30 Topcoat layer 31 Binder resin 32 Antiviral agents 40 adhesive layer 50 Separator

Claims

1. a transparent substrate, a topcoat layer provided on one surface of the transparent substrate, and a pressure-sensitive adhesive layer provided on the other surface of the transparent substrate; the pressure-sensitive adhesive layer has self-adhesive properties, the top coat layer comprises a cured product of a curable resin composition and an antiviral agent, The antiviral sheet, wherein the antiviral agent comprises at least one selected from an antiviral agent in which silver ions are supported on a carrier and an antiviral agent in which silver ions are contained in a carrier.

2. 2. The antiviral sheet according to claim 1, wherein the content of the antiviral agent in the top coat layer is 0.1 parts by mass or more and 20.0 parts by mass or less per 100 parts by mass of the cured product.

3. 3. The antiviral sheet according to claim 1 or 2, wherein the antiviral agent is in the form of particles, and the average particle size of the antiviral agent is 0.1 μm or more and 10 μm or less.

4. An antiviral sheet described in any one of claims 1 to 3, wherein the thickness of the top coat is 1 μm or more and 1000 μm or less.

5. The antiviral sheet according to claim 3 or claim 4, wherein, when the average particle diameter of the antiviral agent is defined as D and the thickness of the top coat layer is defined as T, D / T is 1.0 or less.

6. An antiviral sheet described in any one of claims 1 to 5, wherein at least a portion of the antiviral agent protrudes from the surface of the top coat layer.

7. 7. The antiviral sheet according to claim 1, wherein the adhesive forming the adhesive layer is either a silicone resin or a urethane resin.

8. An antiviral sheet as described in claim 7, wherein the adhesive forming the adhesive layer is a silicone resin.

9. The antiviral sheet according to any one of claims 1 to 8, which has a total light transmittance according to JIS K7361-1:1997 of 86% or more.

10. The antiviral sheet according to any one of claims 1 to 9, having a haze according to JIS K7136:2000 of 20.0% or less.

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