Laminate

Abstract

To provide a laminate that can suppress the decrease in the fungus antiproliferative activity caused by light irradiation and can also suppress the decrease in the fungus antiproliferative activity even after being left in the dark.SOLUTION: A laminate comprises a first layer containing a metal particle, an organic semiconductor, and clay, and a second layer provided on a surface of the first layer, wherein the metal particle consists of a metal constituted of at least one kind selected from the group consisting of gold, silver, copper, aluminum, and platinum, the organic semiconductor consists of a resin containing boron and nitrogen, the clay consists of layered silicate minerals, and the second layer is an insulating layer.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to a laminate.

Background Art

[0002] Conventionally, an antibacterial agent containing a ternary complex formed by mixing silver nanoparticles, an organic semiconductor, and clay in a liquid phase as an antibacterial component has been known (see Patent Document 1 below). This antibacterial agent is known to exhibit antibacterial activity or antiviral activity by receiving light, and unlike a photocatalyst, it exhibits antibacterial activity or antiviral activity even in the dark or indoors, and thus is regarded as promising as an antibacterial agent.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, although the ternary complex described in Patent Document 1 above exhibits antibacterial activity or antiviral activity by light irradiation in a state of direct contact with bacteria or viruses, there is room for improvement in terms of suppressing a decrease in antibacterial activity or antiviral activity when light irradiation is continued. Further, the ternary complex described in Patent Document 1 also has room for improvement in terms of suppressing a decrease in its antibacterial activity or antiviral activity after being left in the dark after light irradiation. In addition, the ternary complex described in Patent Document 1 has the same problems as above in terms of suppressing a decrease in not only antibacterial activity or antiviral activity but also bactericidal activity, antiviral activity, sterilization activity, and virus inactivation activity. Hereinafter, in this specification, bacteria and viruses are collectively referred to as "fungi". Further, antibacterial activity, antiviral activity, bactericidal activity, antiviral activity, sterilization activity, and virus inactivation activity are collectively referred to as "fungal growth inhibitory action".

[0005] The present disclosure has been made in view of the above problems, and an object thereof is to provide a laminate that can suppress a decrease in the fungicidal growth inhibitory effect by light irradiation and can also suppress a decrease in the fungicidal growth inhibitory effect even after being left in the dark after light irradiation.

Means for Solving the Problems

[0006] The inventors of the present disclosure have conducted intensive studies to solve the above problems. As a result, the inventors of the present disclosure have surprisingly found that the above problems can be solved by laminating an insulating layer on the surface of a layer containing metal particles, an organic semiconductor, and clay, leading to the present disclosure.

[0007] That is, one aspect of the present disclosure provides a laminate including a first layer containing metal particles, an organic semiconductor, and clay, and a second layer provided on the surface of the first layer. The metal particles are made of at least one metal selected from the group consisting of gold, silver, copper, aluminum, and platinum. The organic semiconductor is made of a resin containing boron and nitrogen. The clay is made of a layered silicate mineral. The second layer is an insulating layer. According to the laminate of the present disclosure, when the first layer is irradiated with light, the fungicidal growth inhibitory effect by the laminate is exhibited, and a decrease in the fungicidal growth inhibitory effect can be suppressed. Further, even after being left in the dark after light irradiation, a decrease in the fungicidal growth inhibitory effect by the laminate can also be suppressed.

[0008] In the above laminate, the insulating layer may contain a resin. In this case, it becomes difficult for moisture in the air to be absorbed by the second layer, and even if charges are induced in the second layer after irradiating the first layer with light, the charges are less likely to decay. Therefore, a decrease in the fungicidal growth inhibitory effect by the laminate can be further suppressed.

[0009] In the above laminate, the resin may be an acrylic resin. In this case, when the first layer is irradiated with light, the sterilizing action by the laminate is likely to be exhibited, and a decrease in this sterilizing action can be suppressed. Further, even after the laminate is left in a dark place, a decrease in the sterilizing action by the laminate can be suppressed.

[0010] In the above laminate, the relative permittivity of the second layer may be smaller than the relative permittivity of the first layer. In this case, after the first layer is irradiated with light, the amount of charge induced in the second layer can be increased, and the action of suppressing the growth of fungi by the laminate can be further improved.

[0011] In the above laminate, the second layer may have a thickness of 30 μm or less.

[0012] The above laminate may be used for a packaging material. In this case, the packaging material obtained by using the above laminate is likely to exhibit a sterilizing action by light irradiation, and a decrease in this sterilizing action can be suppressed. Further, even after the packaging material is left in a dark place, a decrease in the sterilizing action by the packaging material can be suppressed.

Advantages of the Invention

[0013] According to the present disclosure, there is provided a laminate capable of suppressing a decrease in the action of suppressing the growth of fungi by light irradiation, and also capable of suppressing a decrease in the action of suppressing the growth of fungi even after being left in a dark place after light irradiation.

Brief Description of the Drawings

[0014]

Figure 1

Modes for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present disclosure will be described. Note that the same or equivalent components are denoted by the same reference numerals, and redundant descriptions may be omitted as appropriate.

[0016] <Laminate> 1 is a cross-sectional view showing one embodiment of a laminate of the present disclosure. As shown in Fig. 1, the laminate 100 includes a first layer 10 containing metal particles, an organic semiconductor, and clay, and a second layer 20 provided on the surface of the first layer 10. The metal particles are made of at least one metal selected from the group consisting of gold, silver, copper, aluminum and platinum, the organic semiconductor is made of a resin containing boron and nitrogen, and the clay is made of a layered silicate mineral. The second layer 20 is an insulating layer.

[0017] According to the laminate 100, when the first layer 10 is irradiated with light, the laminate 100 exerts an anti-fungal growth effect, but the decrease in the anti-fungal growth effect can be suppressed. In addition, even after the laminate 100 is left in a dark place after the light irradiation, the decrease in the anti-fungal growth effect of the laminate 100 can be suppressed.

[0018] The reason why the above effect is obtained is unclear, but the inventors of the present disclosure speculate that it may be as follows. That is, when the first layer 10 is irradiated with light, the light causes the electrons in the valence band of the first layer 10 containing metal particles, organic semiconductors, and clay to transition to a conductor, inducing charges. As a result, opposite charges are induced on the front and back surfaces of the first layer 10, respectively. As a result, the first layer 10 exhibits an inhibitory effect on fungal growth. Along with this, polarization occurs in the second layer 20 made of an insulating layer, and opposite charges are also induced on the front and back surfaces of the second layer 20, respectively. As a result, the second layer 20 also exhibits an inhibitory effect on fungal growth, and the laminate 100 as a whole exhibits an inhibitory effect on fungal growth. Therefore, even when fungi do not come into contact with the first layer 10 and are present on the surface of the second layer 20 or in its vicinity, the charges induced on the surface of the second layer 20 inactivate the fungi by electrosterilization, suppressing the growth of the fungi. At this time, since the second layer 20 is in contact with air, the charges on the surface of the second layer 20 may decay due to moisture in the air. However, on the surface of the first layer 10, the charges are less likely to decay due to moisture in the air. Therefore, even if the charges on the surface of the second layer 20 decay, charges are induced again on the surface of the second layer 20 by the charges on the surface of the first layer 10. Therefore, the inventors of the present disclosure speculate that in the laminate 100, even when the inhibitory effect on fungal growth is exhibited by light irradiation, the decrease in the inhibitory effect on fungal growth may be suppressed.

[0019] Also, as described above, when opposite charges are induced on the front and back surfaces of the first layer 10 by light irradiation, the inhibitory effect on fungal growth can continue even after the laminate 100 is left in the dark due to the charge storage effect of the first layer 10. Also, after light irradiation, when left in the dark, the charges on the surface of the second layer 20 may decay due to moisture in the air that comes into contact with the second layer 20. However, on the surface of the first layer 10, the charges are less likely to decay due to moisture in the air. Therefore, even if the charges on the surface of the second layer 20 decay, charges are induced again on the surface of the second layer 20 by the charges on the surface of the first layer 10. Therefore, the inventors of the present disclosure speculate that in the laminate 100, even after being left in the dark, the decrease in the inhibitory effect on fungal growth may be suppressed.

[0020] Hereinafter, the laminate 100 will be described in detail.

[0021] (First layer) The first layer 10 contains metal particles, an organic semiconductor, and clay. The metal particles, the organic semiconductor, and the clay may exist separately or may be combined to form a composite.

[0022] The metal particles contained in the first layer 10 are composed of at least one metal selected from the group consisting of gold, silver, copper, aluminum, and platinum. Among them, since the metal is less likely to rust and is relatively inexpensive, it is preferably silver-containing.

[0023] The average diameter of the metal particles is not particularly limited, and may be 1000 nm or less, or may be 100 nm or less. Also, the average diameter of the metal particles may be 1 nm or more, may be 10 nm or more, or may be 50 nm or more. Note that the average diameter of the metal particles refers to the average value of the particle diameters of the metal particles, and the particle diameter of the metal particles refers to the diameter of a circle (Heywood diameter) when the metal particles are projected onto a plane and replaced with a circle having the same projected area.

[0024] The content of the metal particles in the first layer 10 is not particularly limited, and may be 0.01 mass% or more, or may be 1 mass% or more. Also, the content of the metal particles in the first layer 10 may be 10 mass% or less, or may be 5 mass% or less.

[0025] The organic semiconductor contained in the first layer 10 is composed of a resin containing boron and nitrogen. The organic semiconductor is an organic substance that exhibits semiconductor properties, and the resin containing boron and nitrogen (hereinafter referred to as "boron-nitrogen polymer") may be a charge transfer complex. The boron-nitrogen polymer as a charge transfer complex can be obtained, for example, by reacting a semi-polar organic boron polymer compound with a tertiary amine compound.

[0026] The content rate of the organic semiconductor in the first layer 10 is not particularly limited, and may be 0.02% by mass or more, and may be 2% by mass or more. Further, the content rate of the organic semiconductor in the first layer 10 may be 20% by mass or less, and may be 10% by mass or less.

[0027] The clay contained in the first layer 10 is composed of a layered silicate mineral. Since the layered silicate mineral is easy to synthesize chemically, it is preferably smectite. The clay may or may not coat the metal particles, but when the metal constituting the metal particles contains silver, the clay preferably coats the metal particles. In this case, the toxicity to cells by silver can be suppressed.

[0028] The content rate of the clay in the first layer 10 is not particularly limited, and may be 0.1% by mass or more, and may be 1% by mass or more. Further, the content rate of the clay in the first layer 10 may be 10% by mass or less, and may be 5% by mass or less.

[0029] The thickness of the first layer 10 is not particularly limited, but may be 0.1 μm or more, and may be 1 μm or more. The thickness of the first layer 10 may be 10 μm or less, and may be 5 μm or less.

[0030] The first layer 10 may be a single layer containing metal particles, an organic semiconductor, and clay, or may be composed of two layers, a layer containing metal particles and a layer containing an organic semiconductor and clay. The first layer 10 may further have fibers. From the viewpoint of easily causing polarization in the first layer 10, the fibers preferably have insulating properties. Examples of the insulating fibers include resin fibers made of cellulose, glass fibers made of glass, and mineral fibers made of asbestos.

[0031] (Second layer) The second layer 20 is provided on the surface of the first layer 10. The second layer 20 may be in contact with the surface of the first layer 10. The second layer 20 may also function as a protective layer for the first layer 10.

[0032] The second layer 20 may be an insulating layer. Examples of materials included in the insulating layer include glass, resin, minerals, etc. These can be used alone or in combination of two or more. The material included in the insulating layer may be resin. In this case, it becomes difficult for moisture in the air to be absorbed by the second layer 20. Even if charges are induced in the second layer 20 after irradiating light on the first layer 10, the charges are less likely to decay. Therefore, it is possible to further suppress a decrease in the action of suppressing fungal growth by the laminate 100. Also, when the material included in the insulating layer is resin, the flexibility of the second layer 20 increases, and the flexibility of the laminate 100 increases. Therefore, it becomes easier for the laminate 100 to follow the shape of the surface on which the laminate 100 is installed. Note that, unlike a photocatalyst, the first layer 10 does not extract electrons from other substances such as water to generate active radicals. For this reason, even if the second layer 20 contains resin, it is considered that deterioration of the second layer 20 can be suppressed and the life of the laminate 100 can be extended.

[0033] Examples of resins include vinyl acetate resins, polyolefin resins, acrylic resins, polyester resins, etc. When the resin is an acrylic resin, when light is irradiated on the first layer 10, the sterilization function by the laminate 100 is likely to be exhibited, and a decrease in this sterilization function can be suppressed. Examples of vinyl acetate resins include homopolymers of vinyl acetate, copolymers of vinyl acetate and vinyl chloride, copolymers of vinyl acetate and vinyl alcohol, etc. Examples of polyolefins include polyethylene, polypropylene, and polybutene.

[0034] The relative permittivity of the second layer 20 is not particularly limited, and may be, for example, 2 or more, 3 or more, 3.5 or more, or 4 or more. Further, the relative permittivity of the second layer 20 may be 500 or less, may be 80 or less, or may be 40 or less. In this specification, the relative permittivity refers to a value calculated using the following formula by measuring the capacitance C of a parallel plate capacitor formed by sandwiching a plate-like or sheet-like measurement object, the first layer 10 or the second layer 20 (also referred to as a "sample"), between two flat plate electrodes. ε r =C×d / (ε o S) (ε r : relative permittivity, ε 0 : permittivity of vacuum (8.854×10 -12 F / m), C: capacitance of the parallel plate capacitor (F), S: surface area of the flat plate electrode (m 2 ), d: thickness of the sample (m), measurement frequency: 1 kHz)

[0035] The relative permittivity of the second layer 20 may be greater than the relative permittivity of the first layer 10. In this case, after the first layer 10 is irradiated with light, the amount of charge induced in the second layer 20 can be increased, and the function of suppressing the growth of fungi by the laminate 100 can be further improved. The ratio R of the relative permittivity of the second layer 20 to the relative permittivity of the first layer 10 is not particularly limited, and may be, for example, 0.01 or more, or may be 0.05 or more. Further, R may be 0.3 or less, may be 0.2 or less, or may be 0.1 or less.

[0036] The second layer 20 preferably has translucency. In this case, the first layer 10 can be irradiated with light through the second layer 20. Here, the second layer 20 only needs to be able to transmit light having at least a wavelength absorbed by the first layer 10.

[0037] The thickness of the second layer 20 is not particularly limited and may be 30 μm or less, or may be 20 μm or less. Further, the thickness of the second layer 20 may be 1 μm or more, or may be 2 μm or more. The thickness of the second layer 20 is preferably greater than 3 μm.

[0038] The second layer 20 may be composed of a single layer or may be composed of a plurality of layers made of different materials.

[0039] (Third layer) In addition to the first layer 10 and the second layer 20, the laminate 100 may further include a third layer (not shown). In this case, the third layer is provided on the side opposite to the second layer 20 with respect to the first layer 10. The third layer may be a resin layer. In this case, the charge induced on the back surface of the first layer 10 is less likely to decay, and a decrease in the charge storage effect of the first layer 10 can be suppressed.

[0040] (Applications) The laminate 100 can be used for packaging materials, wallpapers, building materials, etc. In particular, the laminate 100 is preferably used for packaging materials. In this case, the packaging material obtained by using the laminate 100 is likely to exhibit a sterilization effect by light irradiation, and a decrease in this sterilization effect can be suppressed. Further, even after the packaging material is left in a dark place, a decrease in the sterilization effect by the packaging material can also be suppressed.

[0041] The summary of the present disclosure is as follows. [1] A laminate comprising a first layer containing metal particles, an organic semiconductor, and clay, and a second layer provided on the surface of the first layer, wherein the metal particles are made of at least one metal selected from the group consisting of gold, silver, copper, aluminum, and platinum, the organic semiconductor is made of a resin containing boron and nitrogen, the clay is made of a layered silicate mineral, and the second layer is an insulating layer. [2] The laminate according to [1], wherein the insulating layer contains a resin. [3] The laminate according to [2], wherein the resin is an acrylic resin. [4] The laminate according to any one of [1] to [3], wherein the relative permittivity of the second layer is smaller than the relative permittivity of the first layer. [5] The laminate according to any one of [1] to [4], wherein the second layer has a thickness of 30 μm or less. [6] The laminate according to any one of [1] to [5], which is used for a packaging material.

Examples

[0042] The content of the present disclosure will be described in more detail with reference to Examples and Comparative Examples, but the present disclosure is not limited to the following examples.

[0043] (Example 1) <Preparation of ABC Composite Paste> The ABC composite paste was prepared by the following procedure. All reagents used were of special grade manufactured by Wako Pure Chemical Industries, Ltd.

[0044] (Raw Material Liquid A: Preparation of Silver Nanoparticle Aqueous Dispersion) While stirring 10 liters of pure water, 60 mL of a 50 mM aqueous sodium citrate solution and 20 mL of a 100 mM aqueous silver nitrate solution were sequentially added thereto to prepare a first liquid. Also, while stirring 10 liters of ultrapure water, 0.76 g of sodium borohydride was added thereto and dissolved to prepare a second liquid. Subsequently, each of the first liquid and the second liquid was fed into a static mixer at a flow rate of 5 liters / min using a diaphragm pump and mixed to obtain a mixed liquid.

[0045] While stirring this mixed liquid (1650 mL), 407 μL of a 300 mM aqueous sodium citrate solution was added thereto, and further, 990 μL of 30% hydrogen peroxide water was added thereto and stirred for 3 hours. As a result, an aqueous silver nanoparticle dispersion (0.001 mass%) was obtained. At this time, when the average diameter of the silver nanoparticles was measured with the particle size of the silver nanoparticles as the Heywood diameter, the average diameter of the silver nanoparticles was 50 nm.

[0046] (Raw Material Liquid B: Preparation of Organic Semiconductor Solution) As an organic semiconductor, an antistatic agent (BN-2, manufactured by Boron International Co., a polymer BN compound obtained by reacting equimolar amounts of di-glycerin borate, a C34 unsaturated, side-chain dicarboxylic acid ester polymer boron compound, and polyoxyethylene stearylamine (7 mol addition)) was used. 1 g of BN-2 was weighed into a 300 mL beaker, 100 g of ethanol was added, and ultrasonic irradiation was performed to obtain a BN-2 solution as an organic semiconductor solution (BN-2 content: 1 mass%).

[0047] (Preparation of raw material liquid C: Clay dispersion liquid) As the clay, lipophilic synthetic smectite (Smeton-SAN, manufactured by Kunimine Industries Co., Ltd.) was used. 1 g of the white powder of Smeton-SAN was weighed into a 300 mL beaker, 100 g of toluene was added, and ultrasonic irradiation was performed for 15 minutes to obtain a clay dispersion liquid (clay content: 1 mass%).

[0048] (Mixing of three liquids) In a container, raw material liquids A to C were mixed so that the solid content ratio (mass ratio) of silver nanoparticles, BN-2, and Smeton-SAN was 1:2:1. Specifically, to a mixture of raw material liquid B (972 μL) and raw material liquid C (486 μL) in 15 mL of butyl acetate, raw material liquid A (486 mL) was added while stirring at high speed with a stirrer, and the mixture was stirred for several minutes and then left standing overnight. As a result, the liquid in the container phase-separated into a colorless aqueous layer (lower layer) and a butyl acetate layer (upper layer), and a layer composed of a composite of silver nanoparticles, BN-2, and Smeton-SAN (ABC composite) appeared at the interface. The layer composed of this ABC composite was taken into a test tube, and the solvent was distilled off to obtain an ABC composite paste.

[0049] <Preparation of the solution for forming the second layer> A solution for forming the second layer containing 5 mass% of vinyl acetate resin (trade name: vinyl acetate polymer, manufactured by Fuji Film Wako Pure Chemical Corporation) was prepared.

[0050] <Preparation of the laminate> The ABC composite paste obtained as described above was impregnated into a cellulose nanofiber (trade name: Reocristra, manufactured by Daiichi Kogyo Seiyaku Co., Ltd., hereinafter also referred to as "CNF") sheet formed into a flat plate shape and dried to form a first layer with a thickness of 1 μm. At this time, the content ratios of silver nanoparticles, BN-2, clay, and cellulose nanofibers in the first layer were 10% by mass, 20% by mass, 10% by mass, and 60% by mass, respectively. The second layer-forming solution was applied to the surface of the first layer and dried to form a second layer composed of a resin layer with a thickness of 1 μm. Thus, a sample as a laminate was obtained.

[0051] (Example 2) A sample as a laminate was prepared in the same manner as in Example 1, except that the second layer was formed to have a thickness of 5 μm.

[0052] (Example 3) A sample as a laminate was prepared in the same manner as in Example 2, except that a second layer-forming solution containing 10% by mass of an acrylic resin (trade name: Aquabrid, manufactured by Daicel Chemical Industries, Ltd.) was used.

[0053] (Example 4) A first layer with a thickness of 1 μm was formed by applying and drying the ABC composite paste prepared in Example 1 on the surface of a polyethylene terephthalate film (trade name: Lumirror (registered trademark) #38-S10, manufactured by Toray Industries, Inc.) with a thickness of 38 μm as the third layer. Next, a resin solution containing 10% by mass of a copolymer of vinyl acetate (VA) and vinyl chloride (VC) (trade name: Solvain A, manufactured by Nisshin Chemical Industry Co., Ltd.) was applied and dried on the surface of the first layer to form a resin layer (VA-VC copolymer layer) with a thickness of 20 μm. Subsequently, a polypropylene film (trade name: Trephan (registered trademark) #40, manufactured by Toray Industries, Inc.) with a thickness of 38 μm was laminated to form a second layer with a thickness of 58 μm. Thus, a sample as a laminate was prepared. At this time, the content ratios of silver nanoparticles, BN-2, and clay in the first layer were 10% by mass, 20% by mass, and 10% by mass, respectively.

[0054] (Example 5) First, organically modified smectite (Smecton-SEN, manufactured by Kunimine Industries Co., Ltd.), which is a clay soluble in lower alcohols, was ultrasonically dispersed in ethanol to a concentration of 5% by mass to prepare a white dispersion. Then, a 5% by mass ethanol solution of an antistatic agent (BN-2, manufactured by Boron International, a polymeric BN compound obtained by equimolar reaction of diglycerin borate, a C34 unsaturated, side-chain dicarboxylic acid ester polymeric boron compound, and polyoxyethylene stearylamine (7 mol addition)) was added to this white dispersion in an arbitrary ratio, and after further irradiating with ultrasonic waves until the resulting dispersion became translucent, ethanol was volatilized by heating to obtain a semi-solid electrolyte composite (BC composite).

[0055] Next, the above semi-solid electrolyte composite (BC composite) was applied to the surface of a 5 mm thick float glass and dried to form a 1 μm thick BC composite layer.

[0056] Next, a silver nanoparticle aqueous dispersion as raw material liquid A used in Example 1 was applied to the surface of the BC composite layer and dried to form a 0.1 μm thick silver nanoparticle layer (Ag layer). Thus, a first layer composed of a BC composite layer and an Ag layer was formed. At this time, the contents of silver nanoparticles, BN-2, and clay in the first layer were 25% by mass, 50% by mass, and 25% by mass, respectively.

[0057] Next, a glass resin-containing liquid (trade name: Nanoclear SSG, manufactured by TNC Co., Ltd.) containing a total of 27% by mass of an organic compounded glass component (silica glass) composed of tetraethoxysilane and ethyl polysilicate was prepared, and this glass resin-containing liquid was applied to the surface of the Ag layer and dried to form a second layer with a thickness of 2 μm. Thus, a sample as a laminate was produced.

[0058] (Comparative Examples 1 to 5) Samples were produced in the same manner as in Examples 1 to 5 except that the second layer was not formed. In Comparative Example 5, the Ag layer was not surface-protected by clay and was exposed.

[0059] <Measurement of relative permittivity> For the first layer, second layer, and third layer in the samples of Examples 1 to 5 and Comparative Examples 1 to 5, the capacitance of a parallel plate capacitor prepared by sandwiching each layer between two flat electrodes was measured, and the relative permittivity was calculated using the following formula. The results are shown in Table 1. For samples without the second layer or samples without the third layer, the relative permittivity of the third layer was set to "1". ε r = C × d / (ε o S) (ε r : relative permittivity, ε 0 : permittivity of vacuum (8.854 × 10 -12 F / m), C: capacitance of the parallel plate capacitor (F), S: surface area of the flat electrode (m 2 ), d: thickness of the sample (m), measurement frequency: 1 kHz)

[0060] <Evaluation of fungicidal activity> The fungicidal activity of the samples was examined by the following procedure.

[0061] (Preparation of bacterial solution) As the test bacterium, enterohemorrhagic pathogenic Escherichia coli E. coli O157:H7 was used. Specifically, after refreshing the strain of E. coli O157:H7 isolated independently by the Fukuoka Institute of Health and Environmental Sciences, 10 mL of a broth liquid medium inoculated with this was cultured with a shaker (30 °C, 24 hours, 120 rpm). A solution obtained by diluting this culture solution 107-fold was used as the bacterial solution.

[0062] (Fungicidal activity by light irradiation) For the samples of Examples 1 to 5 and Comparative Examples 1 to 5, after dropping 150 μL of the above bacterial solution, the bacterial solution was covered with a polyethylene terephthalate film having a thickness of 38 μm, irradiated with white light of 1000 lux, and the viable cell count was measured after 8 hours. Based on the following formula (1), the fungicidal activity was calculated. The results are shown in Table 1. Fungicidal activity = -log 10 (viable cell count / initial cell count) ··· (1)

[0063] (Inhibitory effect on fungal growth by leaving in the dark after light irradiation) For the samples of Examples 1 to 5 and Comparative Examples 1 to 5, after dropping 150 μL of the above bacterial solution, the bacterial solution was covered with a polyethylene terephthalate film having a thickness of 38 μm, irradiated with white light of 1000 lux for 8 hours, and then left in the dark. Then, the viable cell count was measured after 8 hours, and the inhibitory effect on fungal growth was calculated based on the above formula (1). The results are shown in Table 1.

[0064] (Evaluation of surface potential of samples) The change over time in the surface potential of the samples was examined by the following procedure.

[0065] (Change over time in surface potential by light irradiation) The samples of Examples 1 to 5 and Comparative Examples 1 to 4 were sandwiched between two ITO electrodes (product name: NSG TEC TM 10, manufactured by Nippon Sheet Glass Co., Ltd.), and these two ITO electrodes were connected with a voltmeter (product name: IviumStat, manufactured by Ivium Technologies). Then, white light of 1000 lux was irradiated, and the surface potential V1 (mV) of the second layer or the first layer after 10 hours was measured. And the change amount (increase amount) of the surface potential was calculated based on the following formula (2) using the minimum value Vmin (mV) of the surface potential during the changing irradiation. The results are shown in Table 1. For Comparative Example 5, the change amount of the surface potential was not measured. Change amount of surface potential: ΔV (mV) = V1 - Vmin ···(2)

[0066] (Change over time in surface potential by leaving in the dark after light irradiation) The samples of Examples 1 to 5 and Comparative Examples 1 to 4 were sandwiched between two ITO electrodes (product name: NSG TEC TM10. It was sandwiched with (manufactured by Nippon Sheet Glass Co., Ltd.), and these two ITO electrodes were connected with a voltmeter (product name: Iviumstat, manufactured by Ivium Technologies). Then, after irradiating with white light of 1000 lux, it was left in a dark place, and the surface potential V1d immediately after the start of leaving in the dark of the second layer or the first layer after 10 hours was measured. And the amount of change in surface potential from the maximum value Vmax (mV) of the surface potential during the fluctuating dark storage was obtained based on the following formula (3). The results are shown in Table 1. For Comparative Example 5, since the amount of change in surface potential was not measured, the value of the residual rate is not shown. Amount of change in surface potential in the dark: ΔVd (mV) = V1d - Vmax ···(3) Next, the surface potential residual rate was defined and calculated by the following formula (4). The results are shown in Table 1. Surface potential residual rate (%) = 100×ΔVd / ΔV ···(4) = 100×(V1d - Vmax) / (V1 - Vmin)···(5)

Table 1

[0067] From the results shown in Table 1, the samples of Examples 1 to 5 had a greater inhibitory effect on fungal growth by light irradiation compared to the samples of Comparative Examples 1 to 5 having the same configuration except that the second layer was not formed. Also, the samples of Examples 1 to 4 had a greater inhibitory effect on fungal growth by leaving in the dark after light irradiation compared to the samples of Comparative Examples 1 to 4 having the same configuration except that the second layer was not formed. In addition, from the results shown in Table 1, the samples of Examples 1 to 4 had a greater amount of change in surface potential by light irradiation compared to the samples of Comparative Examples 1 to 4 having the same configuration except that the second layer was not formed. Also, the samples of Examples 1 to 4 had a greater surface potential residual rate by leaving in the dark after light irradiation compared to the samples of Comparative Examples 1 to 4 having the same configuration except that the second layer was not formed. Therefore, it is considered that there is a correlation between the amount of change and the residual rate of the surface potential of the second layer or the first layer and the fungicidal growth inhibitory power.

[0068] From the above, according to the laminate of the present disclosure, it was confirmed that it is possible to suppress a decrease in the fungicidal growth inhibitory action due to light irradiation, and it is also possible to suppress a decrease in the fungicidal growth inhibitory action even after being left in the dark.

Explanation of reference numerals

[0069] 100... laminate, 10... first layer, 20... second layer.

Claims

1. A first layer comprising metal particles, an organic semiconductor, and clay; and a second layer provided on the surface of the first layer, wherein the metal particles are made of a metal composed of at least one selected from the group consisting of gold, silver, copper, aluminum, and platinum, the organic semiconductor is made of a resin containing boron and nitrogen, the clay is made of a layered silicate mineral, and the second layer is an insulating layer, the laminate.

2. The laminate according to claim 1, wherein the insulating layer contains a resin.

3. The laminate according to claim 2, wherein the resin is an acrylic resin.

4. The laminate according to claim 1, wherein the relative permittivity of the second layer is smaller than the relative permittivity of the first layer.

5. The laminate according to claim 1, wherein the second layer has a thickness of 30 μm or less.

6. The laminate according to claim 1, which is used as a packaging material.

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