Composite substrate and method of producing composite substrate

Abstract

To provide a composite substrate firmly holding ceramic particles by the base material thereof while allowing the ceramic particles to fully exhibit inherent antibacterial / antiviral performance.SOLUTION: The composite substrate according to the present invention comprises ceramic particles having antibacterial and antiviral properties, and a base material having a first surface and a second surface disposed on the opposite side of the first surface and containing the ceramic particles, with the ceramic particles being present in a larger amount in the second surface side than in the first surface side in the base material, the ratio of exposed areas of the ceramic particles on the second surface being 30% or more, and the reduction rate (%) of the exposed area ratio of the second surface after carrying out a peel test according to the following peel test method, relative to the exposed area ratio of the second surface being 50% or less. In te peel test method, an adhesive tape specified in JIS Z 1522 is adhered to the second surface, and thereafter the adhesive tape is rapidly and strongly peeled off.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a composite substrate and a method for manufacturing the composite substrate.

Background Art

[0002] As shown in Patent Document 1, as a new type of inorganic material having antibacterial and antiviral properties, ceramics composed of a composite oxide containing rare earths and molybdenum (Mo) or the like are known. Among such ceramics, those composed of a composite oxide containing cerium (Ce) as a rare earth (for example, Ce2Mo3O 13 ) are particularly noted for reasons such as being advantageous for industrial production.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] When particles made of the above-described ceramics are mixed with a base material such as resin or rubber to form a composite, the surface of the particles may be covered by the base material, and antibacterial and antiviral performance (effects) commensurate with the addition amount of the particles may not be obtained.

[0005] In addition, it is also conceivable to manufacture a composite substrate by attaching the particles to the surface of the base material by pressing. However, in the case of the composite substrate thus obtained, the adhesion force (adhesion) of the particles is not sufficient, and when a force (for example, frictional force) is applied from the outside, the particles are easily peeled off from the base material side.

[0006] An object of the present invention is to provide a composite base material in which ceramic particles are firmly held in a base material and the antibacterial and antiviral performance of the ceramic particles is sufficiently exhibited, and a method for producing the same.

Means for Solving the Problems

[0007] The means for solving the above problems are as follows. That is, <1> A composite base material comprising ceramic particles having antibacterial and antiviral properties, a first surface, and a second surface disposed on the opposite side of the first surface, and a base material containing the ceramic particles, wherein the ceramic particles are present more on the second surface side than on the first surface side inside the base material, the exposed area ratio of the ceramic particles on the second surface is 3% or more, and the reduction rate (%) of the exposed area ratio of the second surface after a peeling test based on the following peeling test method with respect to the exposed area ratio of the second surface is 50% or less. Peeling test method: After sticking an adhesive tape specified in JIS Z 1522 to the second surface, the adhesive tape is rapidly and strongly peeled off.

[0008] <2> The composite base material according to <1>, wherein the exposed area ratio of the ceramic particles on the first surface is 30% or less of the exposed area ratio of the ceramic particles on the second surface.

[0009] <3> The composite base material according to <1> or <2>, wherein the exposed area ratio of the ceramic particles on the second surface is 80% or less.

[0010] <4> The composite base material according to <1> or <2>, wherein the blending amount of the ceramic particles with respect to 100 parts by mass of the base material is 0.5 part by mass or more and 10 parts by mass or less.

[0011] <5> A method for manufacturing a composite substrate, comprising the steps of: blending ceramic particles having antibacterial and antiviral properties with a specific gravity difference of 1 or more from the base material into the base material in an uncured state to precipitate the ceramic particles; and curing the base material to expose the ceramic particles on the surface of the base material on the side where the ceramic particles have settled.

Advantages of the Invention

[0012] According to the present invention, it is possible to provide a composite substrate in which ceramic particles are firmly held in a base material and the antibacterial and antiviral performance of the ceramic particles is sufficiently exhibited, and a method for manufacturing the same.

Brief Description of the Drawings

[0013]

Figure 1

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Figure 4

Figure 5

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Figure 7

Embodiments for Carrying Out the Invention

[0014] Hereinafter, the composite substrate according to the embodiment and the method for manufacturing the composite substrate will be described.

[0015] 〔Composite Substrate〕 The composite substrate has ceramic particles having antibacterial and antiviral properties, a first surface, and a second surface disposed on the opposite side of the first surface, and includes a base material containing the ceramic particles.

[0016] The ceramic particles have antibacterial and / or antiviral properties. Antibacterial and / or antiviral properties mean either one or both of antibacterial and antiviral properties. In this specification, antibacterial and / or antiviral properties are represented as antibacterial and antiviral properties.

[0017] The material (ceramic material) constituting such ceramic particles having antibacterial and antiviral properties is not particularly limited as long as the object of the present invention is not impaired. For example, a composite oxide containing a rare earth element and molybdenum (Mo) (hereinafter referred to as "rare earth molybdenum-based composite oxide") can be mentioned. Examples of the rare earth element include lanthanum (La), cerium (Ce), and the like.

[0018] Examples of the rare earth molybdenum-based composite oxide include La-Mo-based composite oxide, Ce-Mo-based composite oxide, La-Mo-W-based composite oxide, and the like. These composite oxides may be used alone or in combination of two or more as long as the object of the present invention is not impaired. The rare earth molybdenum-based composite oxide is used in the form of particles (powder) as ceramic particles.

[0019] The La-Mo-based composite oxide is a composite oxide (lanthanum-molybdenum composite oxide) containing lanthanum (La) and molybdenum (Mo). As the La-Mo-based composite oxide, those having La2Mo2O9 as the main phase (main crystal layer) are preferable. The La-Mo-based composite oxide may consist only of La2Mo2O9, or may contain a lanthanum-molybdenum composite oxide other than La2Mo2O9 as a sub-phase (sub-crystal layer).

[0020] Examples of the lanthanum-molybdenum composite oxide other than La2Mo2O9 include La2Mo3O 12 , La6MoO12 , La7Mo7O 30 , La2Mo4O 15 It may also contain at least one selected from the group consisting of La2MoO6, La4MoO9 and LaMo2O5.

[0021] The Ce-Mo composite oxide is a composite oxide containing cerium (Ce) and molybdenum (Mo) (cerium-molybdenum composite oxide). The Ce-Mo composite oxide is not particularly limited as long as the object of the present invention is not impaired. For example, Ce2Mo3O 13 , Ce(MoO4)2, Ce2MoO6, Ce2(MoO4)3, Ce2Mo4O 15 , Ce5(MoO4)8, Ce6(MoO4)8(Mo2O7), Ce8Mo 12 O 49 and the like. These may be used alone or in combination of two or more.

[0022] The La-Mo-W composite oxide is a composite oxide containing lanthanum (La), molybdenum (Mo), and tungsten (W) (lanthanum-molybdenum-tungsten composite oxide). The La-Mo-W composite oxide is not particularly limited as long as the object of the present invention is not impaired. For example, La2MoWO9, La2Mo x W 2-X O9(0 < x < 2), La2Mo 1.5 W 0.5 O9, La2Mo 0.5 MoW 1.5 O9 and the like. These may be used alone or in combination of two or more.

[0023] The rare earth molybdenum-based composite oxide can be identified by analyzing the X-ray diffraction spectrum obtained by the powder X-ray diffraction method (for example, comparison with known X-ray diffraction spectrum data).

[0024] The rare earth molybdenum-based composite oxide is produced, for example, through a preparation process and a first firing process. Here, the case of producing a powder of the La-Mo composite oxide is illustrated.

[0025] The adjustment step is a step of preparing a mixed powder by mixing a lanthanum compound and a molybdenum compound.

[0026] The lanthanum compound is a compound containing lanthanum (La) necessary for producing a La-Mo-based composite oxide, and examples thereof include La(OH)3, La2O3, La2(CO3)3, etc. As the lanthanum compound, for example, at least one selected from the group consisting of La(OH)3, La2O3, and La2(CO3)3 may be used. Note that La(OH)3 is preferable as the lanthanum compound.

[0027] The molybdenum compound is a compound containing molybdenum (Mo) necessary for producing a La-Mo-based composite oxide, and examples thereof include MoO3, MoO2, MoO, Mo(OH)3, Mo(OH)5, etc. As the molybdenum compound, for example, at least one selected from the group consisting of MoO3, MoO2, MoO, Mo(OH)3, and Mo(OH)5 may be used. Note that MoO3 is preferable as the molybdenum compound.

[0028] The mixing ratio of the lanthanum compound and the molybdenum compound is not particularly limited as long as the object of the present invention is not impaired. For example, it is preferably adjusted so that La:Mo = 1:1 in terms of molar ratio.

[0029] The lanthanum compound and the molybdenum compound are both powders, and they may be mixed with each other in a powder state, or a solvent such as a lower alcohol (ethanol) may be added to these powders for wet mixing. The mixing of the lanthanum compound and the molybdenum compound may be performed, for example, by wet mixing using alumina balls (alumina grinding media), etc. Note that the wet-mixed mixture is appropriately dried by evaporation to dryness, spray drying, etc. Through such an adjustment step, a mixed powder of the lanthanum compound and the molybdenum compound is obtained.

[0030] The first firing step is a step of firing the mixed powder in order to react the lanthanum compound and the molybdenum compound in the mixed powder obtained in the adjustment step. In the first firing step, the mixed powder is fired at a temperature condition of, for example, 500°C or higher and 700°C or lower for 2 hours or more. The first firing step is carried out under a normal atmospheric pressure atmosphere.

[0031] By this first firing step, the lanthanum compound and the molybdenum compound in the mixed powder react to obtain a La-Mo-based composite oxide containing La2Mo2O9 or the like.

[0032] The obtained La-Mo-based composite oxide is processed into a particulate (powder) form having a central particle size within a predetermined range by a pulverization step as needed.

[0033] The pulverization step is a step of obtaining a powdered La-Mo-based composite oxide having a central particle size within a predetermined range by pulverizing the La-Mo-based composite oxide after the first firing using a medium stirring pulverizer such as a bead mill. Various conditions such as the pulverization time are appropriately set so that the central particle size of the La-Mo-based composite oxide falls within a predetermined range. In this way, a powder (particles) of the La-Mo-based composite oxide is obtained.

[0034] The obtained powder of the La-Mo-based composite oxide may be granulated as needed. For example, a slurry is prepared by performing wet mixing and pulverization using alumina balls or the like while adding a solvent such as ethanol to the powder of the La-Mo-based composite oxide, and the dried product of the slurry is passed through a sieve with a predetermined mesh size to obtain a powder of the La-Mo-based composite oxide granulated to a predetermined size.

[0035] Also, as long as the present invention is not impaired, after sintering the La-Mo-based composite oxide after granulation, the obtained sintered body can be pulverized and the resulting pulverized product can be used as ceramic particles. The sintered body can be obtained, for example, by molding the powder of the La-Mo-based composite oxide before sintering into a predetermined shape and firing the obtained molded body under predetermined temperature conditions (for example, 900 °C or higher). In this specification, the firing step performed to sinter the La-Mo-based composite oxide is referred to as the "second firing step". This second firing step can be carried out in an air atmosphere.

[0036] In addition, the La-Mo-based composite oxide obtained after the second firing step may be adjusted to a particulate (powder) form having a central particle diameter within a predetermined range by a pulverization step, if necessary.

[0037] Also, when producing the powder of the Ce-Mo-based composite oxide, in the adjustment step, a cerium compound and a molybdenum compound are mixed to prepare a mixed powder. Examples of the cerium compound include CeO2, cerium nitrate, cerium chloride, cerium sulfate, cerium hydroxide, cerium carbonate, cerium acetate, and the like. As the cerium compound, CeO2 is preferred. Note that as the molybdenum compound, the same ones as those used in the production of the powder of the La-Mo-based composite oxide are used.

[0038] The mixing ratio of the cerium compound and the molybdenum compound is not particularly limited as long as the object of the present invention is not impaired. For example, it may be adjusted so that Ce:Mo = 2:3 in terms of molar ratio, or it may be adjusted so that Ce:Mo = 1:2 in terms of molar ratio, or it may be adjusted so that Ce:Mo = 1:1 in terms of molar ratio, or it may be adjusted so that Ce:Mo = 2:1 in terms of molar ratio, or it may be adjusted so that Ce:Mo = 3:4 in terms of molar ratio, or it may be adjusted so that Ce:Mo = 3:5 in terms of molar ratio. Note that as the mixing ratio, it is preferable to adjust it so that Ce:Mo = 2:3 in terms of molar ratio.

[0039] Also, when manufacturing a powder of a La-Mo-W-based composite oxide, in the adjustment step, a lanthanum compound, a molybdenum compound, and a tungsten compound are mixed to prepare a mixed powder. Examples of the tungsten compound include WO3, WO2, W2O3, etc. WO3 is preferable as the tungsten compound. Note that the same compounds as those used in the production of the powder of the La-Mo-based composite oxide are used as the lanthanum compound and the molybdenum compound.

[0040] The mixing ratio of the lanthanum compound, the molybdenum compound, and the tungsten compound is not particularly limited as long as the object of the present invention is not impaired. For example, it may be adjusted so that the molar ratio is La:Mo:W = 2:1.5 to 0.5:0.5 to 1.5.

[0041] Note that when manufacturing a powder of a Ce-Mo-based composite oxide and a powder of a La-Mo-W-based composite oxide, the same steps as those in the production of the powder of the La-Mo-based composite oxide described above, such as the first firing step and the pulverization step, are performed.

[0042] The rare earth molybdenum-based composite oxide exhibits antibacterial and antiviral properties in both the state of the powder before sintering and the state of the powder after sintering.

[0043] The rare earth molybdenum-based composite oxide exhibits antibacterial properties against Staphylococcus aureus (Gram-positive bacterium), Escherichia coli (Gram-negative bacterium), etc. Also, it is presumed that the rare earth molybdenum-based composite oxide exhibits antibacterial properties against Klebsiella pneumoniae, methicillin-resistant Staphylococcus aureus, Staphylococcus epidermidis, Pseudomonas aeruginosa, multi-drug resistant Pseudomonas aeruginosa, etc.

[0044] In addition, the rare earth molybdenum-based composite oxide exhibits antiviral properties against bacteriophage Qβ, bacteriophage φ6, etc. Note that bacteriophage Qβ has no envelope and is known as an alternative virus to norovirus, and bacteriophage φ6 has an envelope and is known as an alternative virus to influenza virus. Further, it is presumed that the rare earth molybdenum-based composite oxide exhibits antiviral properties against feline calicivirus (an alternative to human norovirus), human influenza virus, swine cholera virus, bovine viral diarrhea virus, border disease virus, giraffe pestivirus, coronavirus, avian influenza virus, etc.

[0045] The central particle diameter of the ceramic particles is not particularly limited as long as the object of the present invention is not impaired. For example, it may be 0.01 μm or more and 10 μm or less. The lower limit value of the central particle diameter is preferably 0.05 μm or more, more preferably 0.1 μm or more, and the upper limit value of the central particle diameter is preferably 8 μm or less, more preferably 5 μm or less. The central particle diameter is determined as the particle diameter (D50) at which the cumulative frequency becomes 50% measured by a laser diffraction type particle size distribution measuring device.

[0046] In addition, the specific gravity of the ceramic particles is not particularly limited as long as the object of the present invention is not impaired. For example, it is preferably larger than the specific gravity of the base material. In particular, it is preferable that the specific gravity difference between the ceramic particles and the base material is 1 or more. Thus, when the specific gravity difference is 1 or more, it is easy to manufacture the composite base material of the present embodiment. The upper limit value of the specific gravity difference is not particularly limited, but may be set to 5 or less, for example.

[0047] The base material is formed in a plate shape having a first surface and a second surface arranged on the opposite side thereof, and constitutes the external shape of the composite base material.

[0048] The ceramic particles are present in a larger amount on the second surface side than on the first surface side inside the base material. The exposed area ratio of the ceramic particles on such a second surface is 3% or more. In addition, it is more preferable that the exposed area ratio of the ceramic particles on the second surface is 30% or more. The upper limit value of the exposed area ratio on the second surface is not particularly limited as long as the object of the present invention is not impaired, and may be, for example, 80% or less. The calculation method of the exposed area ratio will be described later.

[0049] The exposed area ratio of the ceramic particles on the first surface is preferably, for example, 10% or less, more preferably 5% or less, and particularly preferably 1% or less.

[0050] In addition, the exposed area ratio of the ceramic particles on the first surface may be 30% or less of the exposed area ratio of the ceramic particles on the second surface.

[0051] In addition, in the case of this embodiment, the reduction rate (%) of the exposed area ratio of the second surface after the peeling test with respect to the exposed area ratio of the second surface is 50% or less. The reduction rate is preferably 30% or less, more preferably 15% or less, and particularly preferably 10% or less. The calculation method of the reduction rate will be described later.

[0052] The base material is a material that constitutes the external shape of the composite base material and holds the ceramic particles so that the ceramic particles are exposed on the second surface side. In the case of this embodiment, in the manufacturing process, while the ceramic particles gather on the second surface side of the base material due to sedimentation, a part of the ceramic particles is in a state of being exposed from the second surface. As the base material, a resin that can change from a state with fluidity to a solid state in the manufacturing process is used.

[0053] The resin used for the base material is not particularly limited as long as the object of the present invention is not impaired. For example, silicone resin, thermosetting elastomer (such as silicone rubber), thermoplastic elastomer, polyethylene (PE), polypropylene (PP), polyolefin resins such as ethylene-propylene copolymer, acrylic resin, polyethylene terephthalate (PET), polyester resins such as polybutylene terephthalate (PBT), polystyrene resin, acrylonitrile-butadiene-styrene (ABS) resin, modified polyphenylene ether, polyphenylene sulfide, polyamide, polycarbonate, thermoplastic resins such as polyacetal, phenolic resin, epoxy resin, melamine resin, urea resin and other thermosetting resins can be mentioned. These resins may be used alone or in combination of two or more. Note that as the resin used for the base material, an epoxy resin is preferred.

[0054] Note that as the base material, a resin having a specific gravity such that the specific gravity difference from the ceramic particles is 1 or more is selected. The specific gravity of the base material is smaller than that of the ceramic particles.

[0055] The blending amount of the ceramic particles with respect to 100 parts by mass of the base material is not particularly limited as long as the object of the present invention is not impaired. For example, it is preferably 0.5 parts by mass or more and 10 parts by mass or less.

[0056] The base material may contain known additives such as antioxidants, colorants (pigments, dyes, etc.), ultraviolet absorbers, antioxidants, softeners, crosslinking agents, crosslinking aids, curing retarders, curing accelerators, surfactants, fillers, solvents, catalysts, adhesives, natural rubber, and synthetic rubber, in addition to the above-mentioned ceramic particles, as long as the object of the present invention is not impaired.

[0057] The thickness of the base material (the thickness between the first surface and the second surface) is not particularly limited as long as the object of the present invention is not impaired, and may be set to, for example, 10 μm or more and 10 mm or less.

[0058] The composite base material of this embodiment can be used in various applications that require antibacterial and antiviral properties. Further, as long as the composite base material has a first surface and a second surface, it may have other shapes such as a cubic shape or a rectangular parallelepiped shape in addition to a plate shape.

[0059] The composite base material of this embodiment can be manufactured, for example, by a manufacturing method including a sedimentation step and a curing step shown below.

[0060] The sedimentation step is a step of blending ceramic particles having antibacterial and antiviral properties with a specific gravity difference of 1 or more from the base material into an uncured base material and sedimenting the ceramic particles. In this sedimentation step, a thermosetting resin such as an epoxy resin (for example, a two-component epoxy resin composed of a main agent and a curing agent) is used. By blending ceramic particles into an uncured base material (for example, the main agent of an epoxy resin) and further blending a curing agent (the curing agent of the epoxy resin) as necessary, a mixture having fluidity is obtained. When the mixture is poured into a predetermined mold, the ceramic particles sediment in the mold so as to gather toward the bottom surface side of the mold.

[0061] The curing step is a step of curing the base material and exposing the ceramic particles on the surface of the base material on the side where the ceramic particles have sedimented. As described above, when the ceramic particles sediment in a predetermined mold, although the base material has fluidity, as time passes and the base material is allowed to cool, the base material hardens and solidifies. When the base material solidifies in this way, the ceramic particles are held in an exposed state on the surface (second surface) facing the bottom surface of the mold.

[0062] By going through each of the above steps, the composite base material of this embodiment is obtained. Note that as long as the composite base material can be manufactured, it may be manufactured by other manufacturing methods.

Examples

[0063] Hereinafter, the present invention will be described in more detail based on examples. Note that the present invention is not limited by these examples in any way.

[0064] 〔Preparation of La-Mo Composite Oxide (1)〕 As the lanthanum compound, La(OH)3 was prepared, and as the molybdenum compound, MoO3 was prepared. Then, the raw material powder of the lanthanum compound and the raw material powder of the molybdenum compound were weighed so that the molar ratio became 1:1 (La:Mo = 1:1). Each of the weighed raw material powders was mixed with a predetermined amount of ethanol, and the obtained wet mixture was dried to obtain a mixed powder. Next, the mixed powder was calcined in an air atmosphere at a temperature of 550 °C for 10 hours to obtain a calcined powder (semi-calcined powder) composed of a reaction product of the lanthanum compound and the molybdenum compound. And in order to granulate the obtained calcined powder, the operations shown below were performed.

[0065] It was put into a resin pot together with a predetermined amount of ethanol, and the obtained mixture was subjected to wet mixing and grinding using alumina balls to obtain a slurry.

[0066] Thereafter, the obtained slurry was dried at a temperature of 80 °C for about 2 hours, and the obtained dried product was passed through a sieve with an opening of 250 μm to obtain a La-Mo composite oxide powder as a granulated powder. Incidentally, the La-Mo composite oxide was identified as La2Mo2O9 from the X-ray diffraction spectrum obtained by the powder X-ray diffraction method.

[0067] The particle size of the obtained La-Mo composite oxide powder was determined as the volume-based median particle diameter (D50) by the laser diffraction method. Specifically, the median particle diameter (D50) of the La-Mo composite oxide powder was determined using a laser diffraction type particle size distribution measuring device (model "LA-950", manufactured by Horiba, Ltd.). As a result, the median particle diameter was 0.77 μm. Incidentally, the La-Mo composite oxide powder (median particle diameter: 0.77 μm) may be referred to as "LMO1".

[0068] 〔Preparation of La-Mo Composite Oxide (2)〕 The La-Mo composite oxide pulverized by wet pulverization using alumina jade was further wet pulverized in a bead mill for 6 hours, and then La-Mo composite oxide powder was obtained in the same manner as in the above "Preparation (1) of La-Mo composite oxide". The median particle diameter of the obtained La-Mo composite oxide powder was 0.09 μm. The La-Mo composite oxide powder (median particle diameter: 0.09 μm) may be referred to as "LMO2".

[0069] [Preparation (1) of Ce-Mo Composite Oxide] As the cerium compound, CeO2 was prepared, and as the molybdenum compound, MoO3 was prepared. Then, the raw material powder of the cerium compound and the raw material powder of the molybdenum compound were weighed so that the molar ratio was 2:3 (Ce:Mo = 2:3). Each weighed raw material powder was put into a resin container (resin pot), and they were mixed using zirconia jade for 24 hours. The obtained slurry-like wet mixture was dried by simmering to obtain a mixed powder. Next, the mixed powder was calcined temporarily at a temperature of 475 °C for 1 hour in an air atmosphere to obtain a calcined powder (Ce-Mo composite oxide powder) composed of a reaction product of the cerium compound and the molybdenum compound.

[0070] It was put into a resin pot together with a predetermined amount of ethanol, and the mixture was subjected to wet mixing and pulverization using zirconia jade to obtain a slurry.

[0071] Thereafter, the obtained slurry was dried at a temperature of 80 °C for about 2 hours, and the obtained dried product was passed through a sieve with an opening of 250 μm to obtain Ce-Mo composite oxide powder as granulated powder. The Ce-Mo composite oxide was identified as Ce2Mo3O from the X-ray diffraction spectrum obtained by the powder X-ray diffraction method. The Ce-Mo composite oxide powder (median particle diameter: 1.12 μm) may be referred to as "CMO1". 13

[0072] [Preparation (2) of Ce-Mo Composite Oxide] ​A Ce-Mo composite oxide pulverized by wet pulverization using a zirconia gemstone was further wet pulverized in a bead mill for 6 hours, and a Ce-Mo composite oxide powder was obtained in the same manner as in the above "Production of Ce-Mo Composite Oxide (1)" except for this. The median particle diameter of the obtained Ce-Mo composite oxide powder was 0.1 μm. In some cases, the Ce-Mo composite oxide powder (median particle diameter: 0.1 μm) may be referred to as "CMO2".

[0073] [Example 1] LMO1 (specific gravity: 5.7) produced as ceramic particles was added to the main component (liquid) of a curable epoxy resin at a ratio of 1% by mass, and they were thoroughly mixed. Then, a predetermined amount of a curing agent was added to the obtained mixture, and they were thoroughly mixed. Thereafter, the mixture to which the curing agent was added was put into a desired mold and left standing in that state for 10 hours to cure the epoxy resin. In this way, a plate-shaped composite base material (thickness: 1 mm) of Example 1 was obtained. The specific gravity of the epoxy resin is 1.07. In Example 1, the composite base material is formed in the mold such that its lower surface faces the bottom surface side of the mold. Due to the difference in specific gravity between the ceramic particles and the epoxy resin (base material), the ceramic particles settle to the bottom surface side of the mold while the epoxy resin cures, and the ceramic particles are exposed on the lower surface of the composite base material. Therefore, the manufacturing method of the composite base material as in Example 1 is represented as "sedimentation" in Table 1.

[0074] [Example 2] A plate-shaped composite base material (thickness: 1 mm) of Example 2 was produced in the same manner as in Example 1, except that LMO2 (specific gravity: 5.7) was used as the ceramic particles.

[0075] [Example 3] A plate-shaped composite base material (thickness: 1 mm) of Example 3 was produced in the same manner as in Example 1, except that CMO1 (specific gravity: 5.0) was used as the ceramic particles.

[0076] [Example 4] A plate-shaped composite base material (thickness: 1 mm) of Example 4 was produced in the same manner as in Example 1, except that CMO2 (specific gravity: 5.0) was used as the ceramic particles.

[0077] [Example 5] A plate-shaped composite base material (thickness: 1 mm) of Example 5 was produced in the same manner as in Example 1, except that a mixed powder of LMO1 (specific gravity: 5.7) and CMO1 (specific gravity: 5.0) (mass ratio 1:1) was used as the ceramic particles.

[0078] [Comparative Example 1] LMO1 was spread in advance on the bottom surface of the mold, and a mixture of the main agent and the curing agent similar to that in Example 1 was poured into the mold. Then, the mixture was left standing in the mold for 10 hours to cure the epoxy resin. In this way, a plate-shaped composite base material (thickness: 1 mm) of Comparative Example 1 was obtained. The addition amount of LMO1 is the same as that in Example 1. The production method of Comparative Example 1 is represented as "spreading" in Table 1.

[0079] [Comparative Example 2] A plate-shaped composite base material (thickness: 1 mm) of Comparative Example 2 was produced in the same manner as in Example 1, except that epoxy resin (specific gravity: 1.07) and PMMA (methyl methacrylate) beads with a similar specific gravity (specific gravity: 1.19) were prepared and used instead of the ceramic particles.

[0080] [Measurement and Evaluation] (Exposed area ratio of ceramic particles) The exposed area ratio of ceramic particles (such as LMO1) on the lower surface of the composite substrate of Example 1 etc. was determined by the following procedure. First, the lower surface of the composite substrate was photographed using a digital microscope to obtain a microscope image of the lower surface of the composite substrate. For the obtained microscope image, binarization processing was performed while adjusting the luminance threshold value using a predetermined image analysis software (ImageJ, manufactured by the National Institutes of Health, USA) so that the particles (powders) and the regions between the particles could be distinguished. The threshold value was determined by the Yen method. Using the obtained binarized image, the exposed area of the ceramic particles was determined, and from the exposed area and the total area of the observation range in the binarized image, the exposed area ratio (%) of the ceramic particles on the lower surface of the composite substrate was calculated. Also, for the upper surface of the composite substrate, the exposed area ratio (%) of the ceramic particles was calculated in the same manner. The results are shown in Table 1.

[0081] (Microscope image) Regarding the composite substrates of Example 1 etc., the upper surface, lower surface, upper surface side cross-section, and lower surface side cross-section were photographed with a microscope, and the obtained images are shown in FIGS. 1 to 5.

[0082]

Table 1

[0083] FIG. 1 is a diagram showing a microscope image of the composite substrate of Example 1. FIG. 1(A) is a microscope image (magnification: 50 times) of the upper surface of the composite substrate of Example 1, FIG. 1(B) is a microscope image (magnification: 100 times) of the lower surface of the composite substrate of Example 1, FIG. 1(C) is a microscope image (magnification: 100 times) of a part of the upper surface side cross-section which is a part of the cut surface obtained by cutting the composite substrate of Example 1 in the thickness direction, and FIG. 1(D) is a microscope image (magnification: 100 times) of a part of the lower surface side cross-section which is a part of the cut surface obtained by cutting the composite substrate of Example 1 in the thickness direction.

[0084] As shown in Fig. 1 and Table 1, in the composite substrate of Example 1, more LMO1, which is ceramic particles, exists on the lower surface (the second surface) than on the upper surface (the first surface). In the case of Example 1, while the exposed area ratio of the upper surface is 0.1%, the exposed area ratio of the lower surface is 33.1%. In the case of Example 1, since the specific gravity difference between LMO1 and the epoxy resin is as large as 4.63 (=5.7 - 1.07), when the epoxy resin cures, it can be said that LMO1 does not gather on the upper surface side but settles and gathers on the lower surface side.

[0085] Fig. 2 is a diagram showing a microscope image of the composite substrate of Example 2. Fig. 2(A) is a microscope image (magnification: 50 times) of the upper surface of the composite substrate of Example 2, Fig. 2(B) is a microscope image (magnification: 50 times) of the lower surface of the composite substrate of Example 2, Fig. 2(C) is a microscope image (magnification: 100 times) of a part of the upper surface side cross-section which is a part of the cut surface obtained by cutting the composite substrate of Example 2 in the thickness direction, and Fig. 2(D) is a microscope image (magnification: 100 times) of a part of the lower surface side cross-section which is a part of the cut surface obtained by cutting the composite substrate of Example 2 in the thickness direction.

[0086] As shown in Fig. 2 and Table 1, in the composite substrate of Example 2, more LMO2, which is ceramic particles, exists on the lower surface (the second surface) than on the upper surface (the first surface). In the case of Example 2, while the exposed area ratio of the upper surface is 1.0%, the exposed area ratio of the lower surface is 78.7%. In the case of Example 2, since the specific gravity difference between LMO2 and the epoxy resin is as large as 4.63 (=5.7 - 1.07), the same as in Example 1, when the epoxy resin cures, it can be said that LMO2 does not gather on the upper surface side but settles and gathers on the lower surface side. Moreover, in the case of Example 2, due to reasons such as the smaller center particle diameter (D50) of the ceramic particles compared with Example 1, the area (exposed area) where the ceramic particles are exposed from the lower surface is larger.

[0087] Figure 3 is a diagram showing a microscopic image of the composite substrate of Example 3. Fig. 3(A) is a microscopic image (magnification: 50 times) of the upper surface of the composite substrate of Example 3, Fig. 3(B) is a microscopic image (magnification: 50 times) of the lower surface of the composite substrate of Example 3, Fig. 3(C) is a microscopic image (magnification: 100 times) of a part of the upper surface side cross-section which is a part of the cross-section obtained by cutting the composite substrate of Example 3 in the thickness direction, and Fig. 3(D) is a microscopic image (magnification: 100 times) of a part of the lower surface side cross-section which is a part of the cross-section obtained by cutting the composite substrate of Example 3 in the thickness direction.

[0088] As shown in Fig. 3 and Table 1, in the composite substrate of Example 3, more CMO1, which is ceramic particles, exists on the lower surface (the second surface) than on the upper surface (the first surface). In the case of Example 3, while the exposed area ratio of the upper surface is 1.0%, the exposed area ratio of the lower surface is 58.8%. In the case of Example 3, since the specific gravity difference between CMO1 and the epoxy resin is as large as 3.93 (= 5.0 - 1.07), it can be said that when the epoxy resin cures, CMO1 does not gather on the upper surface side but settles and gathers on the lower surface side.

[0089] Figure 4 is a diagram showing a microscopic image of the composite substrate of Example 4. Fig. 4(A) is a microscopic image (magnification: 50 times) of the upper surface of the composite substrate of Example 4, Fig. 4(B) is a microscopic image (magnification: 50 times) of the lower surface of the composite substrate of Example 4, Fig. 4(C) is a microscopic image (magnification: 100 times) of a part of the upper surface side cross-section which is a part of the cross-section obtained by cutting the composite substrate of Example 4 in the thickness direction, and Fig. 4(D) is a microscopic image (magnification: 100 times) of a part of the lower surface side cross-section which is a part of the cross-section obtained by cutting the composite substrate of Example 4 in the thickness direction.

[0090] As shown in Fig. 4 and Table 1, in the composite base material of Example 4, more CMO2, which is ceramic particles, exists on the lower surface (second surface) than on the upper surface (first surface). In the case of Example 4, while the exposed area ratio of the upper surface is 2.4%, the exposed area ratio of the lower surface is 72.4%. In the case of Example 4, since the specific gravity difference between CMO2 and the epoxy resin is as large as 3.93 (=5.0 - 1.07), it can be said that when the epoxy resin cures, CMO2 does not gather on the upper surface side but settles and gathers on the lower surface side. Moreover, in the case of Example 4, due to reasons such as the smaller center particle diameter (D50) of the ceramic particles compared to Example 1, the area (exposed area) where the ceramic particles are exposed from the lower surface is larger.

[0091] Fig. 5 is a diagram showing a microscope image of the composite base material of Example 5. Fig. 5(A) is a microscope image (magnification: 50 times) of the upper surface of the composite base material of Example 5, Fig. 5(B) is a microscope image (magnification: 50 times) of the lower surface of the composite base material of Example 5, Fig. 5(C) is a microscope image (magnification: 100 times) of a part of the upper surface side cross-section, which is a part of the cross-section obtained by cutting the composite base material of Example 5 in the thickness direction, and Fig. 5(D) is a microscope image (magnification: 100 times) of a part of the lower surface side cross-section, which is a part of the cross-section obtained by cutting the composite base material of Example 5 in the thickness direction.

[0092] In the composite base material of Example 5, as the ceramic particles, a mixture in which two types with different center particle diameters are mixed at a mass ratio of 1:1 is used. Specifically, a mixture of LMO1 and CMO1 mixed at a mass ratio of 1:1 is used as the ceramic particles. The specific gravity (average value) of the mixture of LMO1 and CMO1 is 5.35, and the center particle diameter (average value) of the mixture is 0.945. As shown in FIG. 5 and Table 1, in such a composite base material of Example 5, more CMO2, which is a ceramic particle, exists on the lower surface (second surface) than on the upper surface (first surface). In the case of Example 5, the exposed area ratio of the upper surface is 0.2%, while the exposed area ratio of the lower surface is 53.2%. In the case of Example 5, since the specific gravity difference between the mixture of LMO1 and CMO1 and the epoxy resin is as large as 4.28 (=5.35 - 1.07), it can be said that when the epoxy resin is cured, LMO1 and CMO1 do not gather on the upper surface side but settle and gather on the lower surface side.

[0093] Unlike Example 1 and the like, the composite base material of Comparative Example 1 is manufactured by pouring a mixture of the main agent and the curing agent of the epoxy resin into a mold in which LMO1, which is a ceramic particle, is pre-laid on the bottom surface. Even with such a manufacturing method, as shown in Table 1, a composite base material in which more LMO1 exists on the lower surface (second surface) than on the upper surface (first surface) can be produced. In the case of Comparative Example 1, the exposed area ratio of the upper surface is 0.1%, and the exposed area ratio of the lower surface is 97.8%. However, as will be described later, the composite base material of Comparative Example 1 has a drawback that the epoxy resin (base material) has a weak force to hold the ceramic particles, and the ceramic particles are easily peeled off from the lower surface side.

[0094] The composite substrate of Comparative Example 2 contains PMMA beads having a specific gravity close to that of the epoxy resin instead of ceramic particles. When the composite substrate of Comparative Example 2 was produced in the same manner as in Example 1 and the like, as shown in Table 1, the exposed area ratio of the upper surface was 44.5% and the exposed area ratio of the lower surface was 50.0%. That is, in the case of Comparative Example 2, the specific gravity difference between the PMMA beads and the epoxy resin was as small as 0.12 (= 1.19 - 1.07), and the PMMA beads could not be sedimented so as to gather on the lower surface side.

[0095] As described above, in the composite substrates of Examples 1 to 5, when the epoxy resin is cured, the ceramic particles are likely to sediment and gather on the lower surface side. Therefore, more ceramic particles are present on the lower surface (second surface) than on the upper surface (first surface). Moreover, the ceramic particles are not merely gathered on the lower surface (second surface), but are present on the lower surface side in a state firmly fixed to the epoxy resin as the base material.

[0096] (Peel test) <Test 1> Here, as a representative of the examples, a peel test was performed on the composite substrate of Example 2 by the method shown below while conforming to JIS H 8504-1999 (Adhesion test method for plating). This peel test examines the adhesion of the ceramic particles by attaching an adhesive tape to the lower surface of the composite substrate and rapidly and strongly peeling it off. The adhesive tape was specified in JIS Z 1522, and one having a nominal width of 18 mm was used. The adhesive force of the adhesive tape is about 8 N per 25 mm width.

[0097] The adhesive tape was attached by selecting as flat a portion as possible from the lower surface of the composite substrate. At that time, a blank portion that protrudes outside the lower surface and cannot be attached to the lower surface is formed on the adhesive tape with a length of 30 mm to 50 mm. When attaching the adhesive tape, the surface of the adhesive tape was continuously and strongly pressed with a rubber jig (which can be substituted with an eraser) for about 10 seconds so that no bubbles were formed between the adhesive tape and the lower surface. Then, with the blank portion of the adhesive tape, the adhesive tape was instantaneously peeled off from the lower surface by strongly pulling it in a state where the blank portion was arranged perpendicular to the lower surface. And the exposed area ratio of the ceramic particles at the location where the adhesive tape was peeled off was determined by the same method as the method described above. The exposed area ratio of the ceramic particles immediately before (right before) the peeling test was also determined by the same method. Also, from the exposed area ratio before the peeling test and the exposed area ratio after the peeling test, the reduction rate (%) of the exposed area ratio was determined. The results are shown in Table 2.

[0098] <Test 2> Also, for the composite substrate of Comparative Example 1, a peeling test was conducted in the same manner as in Test 1 above. The results are shown in Table 2.

[0099]

Table 2

[0100] Figure 6 is a diagram showing microscope images of the lower surface of the composite substrate of Example 2 before and after the peeling test. Figure 6(A) is the microscope image (magnification: 50 times) of the lower surface before the peeling test, and Figure 6(B) is the microscope image (magnification: 50 times) of the lower surface after the peeling test. In the case of Example 2, even when the adhesive tape was attached to the lower surface and strongly peeled off, the ceramic particles did not peel off from the lower surface and remained on the lower surface as it was. That is, in the case of Example 2, it can be said that the adhesion of the ceramic particles to the lower surface is excellent. In other words, it can be said that the epoxy resin as the base material firmly holds the ceramic particles. The reduction rate (%) of the exposed area ratio of Example 2 was 0% (=〔(87.1 - 87.1) / 87.1〕×100).

[0101] FIG. 7 is a diagram showing a microscopic image of the lower surface of the composite base material of Comparative Example 1 before and after the peeling test. FIG. 7(A) is a microscopic image (magnification: 50 times) of the lower surface before the peeling test, and FIG. 7(B) is a microscopic image (magnification: 50 times) of the lower surface after the peeling test. In the case of Comparative Example 1, it was confirmed that when an adhesive tape was attached to the lower surface and strongly peeled off, the ceramic particles were easily peeled off from the lower surface. That is, in the case of Comparative Example 1, the adhesion of the ceramic particles to the lower surface was not sufficient, and it can be said that the epoxy resin as the base material had a weak force (holding force) to hold the ceramic particles. The reduction rate (%) of the exposed area ratio in Comparative Example 1 was 77.2% (= [(87.8 - 20.0) / 87.8] × 100).

Claims

1. Ceramic particles having antibacterial and antiviral properties, a base material having a first surface and a second surface disposed on the opposite side of the first surface, and containing the ceramic particles. The ceramic particles are present in a larger amount on the second surface side than on the first surface side inside the base material. The exposed area ratio of the ceramic particles on the second surface is 3% or more. A composite base material in which the reduction rate (%) of the exposed area ratio of the second surface after a peeling test based on the following peeling test method with respect to the exposed area ratio of the second surface is 50% or less. Peeling test method: After sticking an adhesive tape defined in JIS Z 1522 to the second surface, the adhesive tape is rapidly and strongly peeled off.

2. The exposed area ratio of the ceramic particles on the first surface is 30% or less of the exposed area ratio of the ceramic particles on the second surface. The composite base material according to claim 1.

3. The exposed area ratio of the ceramic particles on the second surface is 80% or less. The composite base material according to claim 1 or claim 2.

4. The compounding amount of the ceramic particles with respect to 100 parts by mass of the base material is 0.5 part by mass or more and 10 parts by mass or less. The composite base material according to claim 1 or claim 2.

5. A step of blending antibacterial and antiviral ceramic particles having a specific gravity difference of 1 or more with the base material in an uncured state and sedimenting the ceramic particles, A method for producing a composite base material, comprising a step of curing the base material to expose the ceramic particles on the surface of the base material on the side where the ceramic particles have sedimented.

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