Silicone coating film, laminated structure, and method for producing laminated structure

Abstract

The present invention addresses the problem of providing: a silicone coating film having high transparency in the visible light region while ensuring resistance to ultraviolet rays; a laminated structure having the silicone coating film; and a method for producing the laminated structure. As a solution, a second layer (11), which is a coating film provided as a surface layer of an irradiated body that is irradiated with ultraviolet light, is made of silicone rubber as a base material (111), and contains titanium oxide particles (113) having an average particle diameter of less than 100 nm. In the laminated structure (1), a second layer (11) having a silicone rubber as a base material (111) is laminated on a first layer (10) having a silicone rubber as a base material (101), and the second layer (11) contains fine titanium oxide particles (113) having an average particle diameter of less than 100 nm.

Description

Technical Field

[0001] This invention relates to silicone coatings based on silicone rubber, and particularly to silicone coatings provided as the surface layer of an irradiated body subjected to sterilization treatment by ultraviolet irradiation, a laminated structure having the silicone coating, and a method for manufacturing the laminated structure. Background Technology

[0002] In the past, medical devices such as ultrasound probes used in medicine have been sterilized by ultraviolet irradiation before or after use to prevent infection. As a sheath covering multiple wires and a shielding layer in the probe cable of an ultrasound probe, as well as a coating covering the surface of the sheath, the applicant has proposed a laminated structure as described in Patent Document 1.

[0003] The laminated structure described in Patent Document 1 is a two-layer structure comprising a first layer and a second layer with silicone rubber as the base material. The first layer contains various crosslinking agents, crosslinking catalysts, anti-aging agents, plasticizers, lubricants, fillers, flame retardants, stabilizers, and colorants. The second layer contains silicone resin microparticles, titanium dioxide microparticles, and nano-silica microparticles.

[0004] In this second layer, silicone resin microparticles are used to impart an uneven surface to improve slipability, while titanium dioxide microparticles are used to shield ultraviolet light through absorption and / or scattering, thereby improving UV resistance. Additionally, nano-silica microparticles are used to uniformly disperse the titanium dioxide microparticles in the second layer. It should be noted that in Patent Document 1, the average particle size of the silicone resin microparticles is 1 μm to 10 μm, the average particle size of the titanium dioxide microparticles is 100 nm to 300 nm, and the average particle size of the nano-silica microparticles is 10 to 30 nm.

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Application Publication No. 2024-51299 Summary of the Invention

[0008] The problem that the invention aims to solve

[0009] Furthermore, in the layered structure described in Patent Document 1 above, for example, considering design, it is sometimes desirable to make the appearance of the first layer colorful, but the following issues exist.

[0010] Specifically, regarding the various microparticles (silicone resin microparticles, titanium dioxide microparticles, and nano-silica microparticles) added to the second layer of the silicone coating to improve resistance to ultraviolet light, among these microparticles, titanium dioxide microparticles are white. Therefore, even if the first layer is intentionally colored, the appearance observed through the second layer appears cloudy, resulting in reduced design flexibility. The desired design flexibility is transparency in the visible light region.

[0011] As a means of addressing the aforementioned issues, one could consider reducing the amount of titanium dioxide particles added in the second layer; however, in this case, it may be impossible to ensure resistance to ultraviolet radiation.

[0012] Therefore, the object of the present invention is to provide an organosilicon coating that ensures resistance to ultraviolet light while also being transparent in the visible light region, a laminated structure having the organosilicon coating, and a method for manufacturing the laminated structure.

[0013] Methods for solving problems

[0014] To address the aforementioned issues, this invention provides an organosilicon coating that serves as the surface layer of an irradiated object subjected to ultraviolet radiation. The coating uses silicone rubber as the base material and contains titanium oxide microparticles with an average particle size of less than 100 nm.

[0015] In addition, in order to solve the above-mentioned problems, the present invention provides a laminated structure, which is a laminated structure having a second layer stacked on a first layer with silicone rubber as the base material, wherein the second layer is the aforementioned organosilicon coating.

[0016] In addition, to solve the above-mentioned problems, the present invention provides a method for manufacturing a laminated structure, which is a method for manufacturing a laminated structure in which a second layer containing titanium oxide microparticles with an average particle size of less than 100 nm is laminated on a first layer containing silicone rubber as a base material. The method includes: a preparation step, preparing a liquid mixture of the silicone rubber component, which serves as the base material for the second layer, and an organic solvent; a first dispersion step, adding an organosilicon surfactant to the liquid mixture to disperse the added organosilicon surfactant; a second dispersion step, after the first dispersion step, further adding the titanium oxide microparticles to the liquid mixture to disperse the added titanium oxide microparticles; a raw material attachment step, setting the liquid mixture as a liquid resin composition serving as the raw material for the second layer, and attaching the liquid resin composition to the surface of the first layer; and a layer formation step, solidifying the silicone rubber component by vaporizing the organic solvent contained in the liquid resin composition attached to the surface of the first layer, thereby forming the second layer.

[0017] Invention Effects

[0018] According to the present invention, it is possible to provide an organosilicon coating that has transparency in the visible light region while ensuring resistance to ultraviolet light, a laminated structure having the organosilicon coating, and a method for manufacturing the laminated structure. Attached Figure Description

[0019] Figure 1 This is a vertical cross-sectional view of the stacked structure according to an embodiment of the present invention.

[0020] Figure 2 In the image, (a) is a top view of a printed medium with printed text. (b) and (c) are top views of a sample with an organosilicon coating formed on the surface of quartz glass.

[0021] Figure 3 This is an example of a graph showing the relationship between the average particle size of titanium oxide particles dispersed in the parent material and the light transmittance at various wavelengths.

[0022] Figure 4 This is a figure illustrating an example of the relationship between the average particle size of titanium oxide particles dispersed in the parent material and the presence or absence of surfactants and transmittance.

[0023] Figure 5 In the diagram, (a) is a configuration diagram showing an application example of the laminated structure of this embodiment to the probe cable of a medical ultrasound probe, and (b) is a cross-sectional view at line AA in (a).

[0024] Symbol Explanation

[0025] 1: Layered structure, 10: First layer, 101, 111: Base material, 11: Second layer, 112: Silicone resin microparticles, 113: Titanium oxide microparticles, 114: Nano silica microparticles, 4: Probe cable (irradiated object), 44: Sheath (first layer), 45: Silicone coating (second layer). Detailed Implementation

[0026] [Implementation Method]

[0027] (The composition of a layered structure)

[0028] Figure 1 This is a schematic diagram illustrating a vertical cross-section of a laminated structure 1 according to an embodiment of the present invention. The laminated structure 1 is a two-layer structure comprising a first layer 10 with silicone rubber as the base material 101 and a second layer 11 laminated on the first layer 10. The second layer 11 has silicone rubber as the base material 111 and includes silicone resin particles 112, titanium dioxide (TiO2) particles 113, and nano-silica particles 114. The second layer 11 is transparent in the visible light region, allowing the color or text of the first layer 10 to be visually discerned through the second layer 11.

[0029] The laminated structure 1 is disposed on the object to be irradiated by ultraviolet light. The second layer 11 is a coating film disposed as the surface layer of the irradiated object, equivalent to the silicone coating film of the present invention. The second layer 11 is directly irradiated by ultraviolet light. That is, the second layer 11 is a coating film constituting the surface layer of the laminated structure 1 to be irradiated by ultraviolet light. Here, ultraviolet light in ultraviolet irradiation refers to near-ultraviolet light including UV-A with wavelengths of 315-380 nm, UV-B with wavelengths of 280-315 nm, and UV-C with wavelengths of 200-280 nm.

[0030] The silicone rubber used as the base material 101 of the first layer 10 and the base material 111 of the second layer 11 is a type of organosilicon resin. Compared with polyvinyl chloride, which is commonly used as a material for medical cables and pipes, silicone rubber has higher resistance to ultraviolet light.

[0031] The laminated structure 1 can take various forms depending on its application. For example, when used as insulation for cables and pipes, the laminated structure 1 is formed into a tubular shape. Conversely, when used as sheet material for greenhouses or sterilization chambers, the laminated structure 1 is formed into a sheet shape. When the laminated structure 1 is used as sheet material for greenhouses, it can block ultraviolet rays received from the outside, inhibiting their intrusion into the greenhouse. When the laminated structure 1 is used as sheet material for sterilization chambers, it can prevent ultraviolet rays used for sterilization from leaking out of the sterilization chamber.

[0032] (The composition of the second layer)

[0033] The second layer 11 is equivalent to a coating film covering the surface of the first layer 10. Its raw material is a liquid resin composition (silicone rubber coating agent) containing silicone rubber as a base material 111 and comprising silicone resin particles 112, titanium dioxide particles 113, and nano-silica particles 114. The silicone rubber used as the base material 111 of the second layer 11 can be, for example, an addition-reaction type silicone rubber coating agent or a condensation-reaction type silicone rubber coating agent. In particular, from the viewpoint of adhesion to the first layer 10 and abrasion resistance, an addition-reaction type silicone rubber coating agent is preferred.

[0034] Here, "abrasion resistance" in this application specification refers to the following characteristics: as described in paragraphs

[0108] to

[0112] of Japanese Patent Application Publication No. 2021-45525, such that 2×10 -3 MPa~4×10 -3The shear stress of MPa is assessed by wiping the surface of the second layer 11 with a long-fiber nonwoven fabric (50mm in the wiping direction) soaked in disinfectant alcohol against the fabric. The wiping length is 150mm, and the wiping speed is 80-120 times per minute. The test is repeated 20,000 times. Before and after the test, the difference (absolute value) in the static friction coefficient of the second layer 11 is less than 0.1. It should be noted that shear stress refers to the pull-out force (resistance during pull-out) generated when the cable is pressed against the fabric with the cotton cloth soaked in disinfectant alcohol and then pulled out of the cloth.

[0035] It should be noted that, in order to obtain good sliding properties and abrasion resistance on the surface of the laminated structure 1, the thickness T2 of the second layer 11 is preferably 3 μm or more. There is no particular upper limit to the thickness of the second layer 11, but from the viewpoints of productivity, high flexibility, and high bending resistance, it is preferably 100 μm or less. Alternatively, the second layer 11 can also be laminated on both sides of the first layer 10.

[0036] Silicone resin microparticles 112 are incorporated into the second layer 11 to impart unevenness to the surface 11a of the second layer 11. If unevenness exists on the surface 11a, the contact area between the second layer 11 and the contact object is smaller and the sliding property is higher compared to the case where the surface 11a is flat.

[0037] Compared to silicone rubber, silicone resin has fewer reactive groups (e.g., methyl groups) and higher hardness. Therefore, compared to silicone rubber microparticles, silicone resin microparticles 112 can effectively suppress surface deformation of the second layer 11 when it comes into contact with the contacting object. This is because the higher the hardness of the microparticles, the more effectively they can suppress surface deformation of the second layer 11 when pressure is applied to its surface by the contacting object. Thus, the increase in the contact area between the second layer 11 and the contacting object can be suppressed, maintaining slipability.

[0038] Furthermore, the bond energies between atoms in the molecular structure of organosilicon resin are higher than those in the molecular structure of silicone rubber. Therefore, organosilicon resin exhibits higher resistance to UV-C light compared to silicone rubber. The bond energy of the abundant CH bonds in silicone rubber (approximately 4.27 eV) is lower than the energy of UV-C light (approximately 6.2 eV), causing these bonds to break upon UV-C irradiation. However, the bond energy of the abundant Si-O bonds in organosilicon resin (approximately 6.52 eV) is higher than the energy of UV-C light, preventing bond breakage upon UV-C irradiation. Therefore, in terms of resistance to UV-C light, organosilicon resin particles 112 are superior to silicone rubber particles.

[0039] The average particle size of the silicone resin particles 112 is, for example, 1 μm or more and 10 μm or less. The term "average particle size" in this specification also includes the average particle size of the titanium dioxide particles 113 and the nano-silica particles 114 described later, and refers to the average particle size measured by laser diffraction scattering. Furthermore, the concentration of the silicone resin particles 112 in the second layer 11 is, for example, 10% by mass or more and 60% by mass or less. Here, the concentration of the silicone resin particles 112 is a value calculated assuming that all the silicone rubber component of the silicone rubber coating (silicone rubber component + organic solvent) is cured into silicone rubber (a value approximately equivalent to the mixing mass ratio). More specifically, it is the mass of the silicone resin particles 112 divided by the total mass of the silicone resin particles 112 and the silicone rubber component in the silicone rubber coating, expressed as a percentage. On the other hand, the concentration of nano-silica particles 114 is a value calculated by dividing the mass of nano-silica particles 114 by the mass of the silicone rubber component in the silicone rubber coating and expressing it as a percentage. However, it can also be calculated similarly to the concentration of organosilicon resin particles 112, by dividing the mass of nano-silica particles 114 by the total mass of nano-silica particles 114 and the silicone rubber component in the silicone rubber coating and expressing it as a percentage. It should be noted that the concentration of nano-silica particles 114 in this application specification is a value calculated using the former method.

[0040] The titanium dioxide particles 113 contained in the second layer 11 can shield ultraviolet light through absorption and / or scattering. By shielding ultraviolet light with titanium dioxide particles 113, the degradation of the first layer 10 and the second layer 11, which are based on silicone rubber as the base material 101 and 111, caused by ultraviolet light can be suppressed. In particular, the degradation of the base material 101 and 111 caused by UV-C light (ultraviolet light of 200-280 nm) can be suppressed. The TiO2 constituting the titanium dioxide particles 113 can be any one of anatase, rutile, or brookite, or a mixture of two or more of them. In addition, niobium oxide can be added to the titanium dioxide to make it stable.

[0041] Regarding the Ti concentration (titanium concentration) of the second layer 11, when it is, for example, a high concentration exceeding 4.4% by mass, the surface roughness of the second layer 11 increases due to the influence of titanium oxide. As a result, dirt and bacteria not only adhere easily but are also difficult to remove. Furthermore, the adhesion between the silicone rubber substrate 111 and the silicone resin particles 112 is reduced, so the silicone resin particles 112 easily detach from the substrate 111. Consequently, the unevenness of the surface 11a of the second layer 11 imparted by the silicone resin particles 112 disappears, and the slippage of the surface of the second layer 11 decreases.

[0042] Additionally, if the Ti concentration in the second layer 11 is 0.5% by mass or higher, then under irradiation at 1404 J / cm²... 2In a bending test equivalent to 45-50% stretching of the laminated structure 1 after UV-C light exposure, the generation of cracks from the surface of the laminated structure 1 to the first layer 10 can be suppressed. It should be noted that, as described in paragraphs

[0106] to

[0110] of Patent Document 1, a test piece on which the laminated structure 1 is formed on one side is wound around a cylindrical wire in such a way that the second layer 11 is subjected to an elongation of 45-50%, and the outer peripheral surface of the wound portion of the test piece (the surface of the second layer 11) is observed with an optical microscope.

[0043] Therefore, the Ti concentration of the second layer 11 is preferably 0.5% by mass or more and 4.4% by mass or less. By making the Ti concentration of the second layer 11 0.5% by mass or more and 4.4% by mass or less, the surface roughness of the second layer 11 can be suppressed, the surface lubrication of the second layer 11 can be improved, and the generation of cracks in the second layer 11 can be suppressed.

[0044] It should be noted that the Ti in the second layer 11 is all contained as an oxidized element in the titanium oxide particles 113. The Ti concentration in the second layer 11 is determined by using an energy dispersive X-ray analyzer (EDS) mounted on a scanning electron microscope (SEM) as the average value in a measurement area of ​​125 μm x 95 μm. All the Ti in this Ti concentration originates from the titanium oxide particles 113.

[0045] The titanium oxide particles 113 included in the second layer 11 can be titanium oxide particles with a hydrophobic surface treatment. This configuration suppresses the formation of aggregates of titanium oxide particles 113 on the surface of the second layer 11, thus allowing the titanium oxide particles 113 to be uniformly dispersed within the second layer 11. Similarly, the nano-silica particles 114 can also be nano-silica particles with a hydrophobic surface treatment. This configuration suppresses the formation of aggregates of nano-silica particles 114 on the surface of the second layer 11, thus allowing the titanium oxide particles 113 to be uniformly dispersed within the second layer 11. Furthermore, by using particles with a hydrophobic surface treatment as titanium oxide particles 113 and nano-silica particles 114 respectively, not only is the formation of aggregates of titanium oxide particles 113 and nano-silica particles 114 suppressed, but also the formation of aggregates of titanium oxide particles 113 and silicone resin particles 112, and aggregates of nano-silica particles 114 and silicone resin particles 112, are suppressed.

[0046] Nano-silica particles 114 are contained in a liquid resin composition (silicone rubber coating agent) that serves as the raw material for the second layer 11, imparting thixotropy. At this point, the nano-silica particles 114 form a large-volume network structure in the liquid. This configuration delays the settling rate of the silicone resin particles 112 and the titanium oxide particles 113, thus suppressing settling. It should be noted that the average particle size of the nano-silica particles 114 is smaller than the average particle size of the titanium oxide particles 113, being 10 nm or more and 30 nm or less, for example, 15 nm.

[0047] To effectively suppress the sedimentation of silicone resin particles 112 and titanium dioxide particles 113, from the viewpoint of imparting thixotropy, the concentration of nano-silica particles 114 in the second layer 11 is preferably 1.0% by mass or more, but if it exceeds 7.0% by mass, the color of the first layer 10 seen through the second layer 11 will become cloudy, so it is preferably 7.0% by mass or less. That is, the concentration of nano-silica particles 114 in the second layer 11 is preferably 1.0% by mass or more and 7.0% by mass or less. By constructing the second layer 11 in this way, it is possible to suppress the cloudiness of the color of the first layer 10 observed through the second layer 11, and to suppress the sedimentation of silicone resin particles 112 and titanium dioxide particles 113, so that the silicone resin particles 112 and titanium dioxide particles 113 are uniformly dispersed in the liquid resin composition.

[0048] (The composition of the first layer)

[0049] To suppress degradation caused by ultraviolet light transmitted through the second layer 11, the first layer 10 may contain titanium dioxide particles, just like the second layer 11. Furthermore, as described above, the first layer 10 uses silicone rubber as the base material 101. However, when the laminated structure 1 is applied to a cable covering multiple wires, and the cable sheath is used as the first layer 10 of the laminated structure 1, silicone rubber containing various crosslinking agents, crosslinking catalysts, anti-aging agents, lubricants, plasticizers, fillers, flame retardants, stabilizers, and colorants can be used as the base material 101. Additionally, the first layer 10 may contain an organic ultraviolet absorber instead of titanium dioxide particles, or it may contain both titanium dioxide particles and an organic ultraviolet absorber. It should be noted that the thickness T1 of the first layer 10 is set according to the intended use of the laminated structure 1 (cable, pipe, or various sheets).

[0050] (Manufacturing method of layered structures)

[0051] A method for manufacturing a laminated structure 1 having a first layer 10 with silicone rubber as the base material 101 and a second layer 11 with silicone rubber as the base material 111 and containing titanium oxide microparticles 113 with an average particle size of less than 100 nm laminated on the first layer 10 includes: a raw material manufacturing step for manufacturing a liquid resin composition as a raw material for the second layer 11; a raw material attachment step for attaching the liquid resin composition manufactured in the raw material manufacturing step to the surface of the first layer 10; and a layer forming step for vaporizing (based on heated vaporization) the organic solvent contained in the liquid resin composition attached in the raw material attachment step to cure the silicone rubber component, thereby forming the second layer 11.

[0052] The aforementioned raw material manufacturing process includes: a preparation step, which prepares a liquid mixture of silicone rubber components (i.e., silicone rubber components and organic solvents) that constitute the base material of the second layer 11; a first dispersion step, which adds an organosilicon surfactant (polyether-modified silicone oil) to the liquid mixture prepared in the preparation step and applies ultrasound to the added organosilicon surfactant to disperse it uniformly; a second dispersion step, which further adds titanium oxide particles 113 to the liquid mixture after the first dispersion step and applies ultrasound to the added titanium oxide particles 113 to disperse it uniformly; a third dispersion step, which adds nano-silica particles 114 with an average particle size smaller than that of the titanium oxide particles 113 to the liquid mixture after the second dispersion step and applies ultrasound to the added nano-silica particles 114 to disperse it uniformly; and a fourth dispersion step, which further adds organosilicon resin particles 112 with an average particle size of 1 μm or more to the liquid mixture after the third dispersion step and applies ultrasound to the added organosilicon resin particles 112 to disperse it uniformly.

[0053] It should be noted that the application conditions for the above ultrasonic waves are all the same, and the ultrasonic cleaning mode using a near dual-frequency ultrasonic cleaner (model: VS-D 100) manufactured by AS ONE Co., Ltd., with high-speed switching between 24kHz and 31kHz dual-frequency oscillation, lasts for 10 minutes.

[0054] Therefore, the liquid mixture (silicone rubber component + organic solvent) obtained through the raw material manufacturing process becomes a liquid resin composition (silicone rubber coating agent) as the raw material for the second layer 11. This liquid resin composition contains, in addition to, organosilicon resin particles 112, titanium dioxide particles 113, nano-silica particles 114, silicone rubber, and organic solvent, an organosilicon surfactant. By including an organosilicon surfactant in the liquid resin composition as the raw material for the second layer 11, the organosilicon surfactant can adhere to the titanium dioxide particles 113 when they are dispersed in the liquid mixture, thus inhibiting the aggregation of the titanium dioxide particles 113. As a result, the titanium dioxide particles 113 can be uniformly dispersed.

[0055] It should be noted that, as an organosilicon surfactant, organosilicon surfactants used in cosmetics are preferred. More specifically, examples include polyglycerol-modified silicone oil and polyether-modified silicone oil. Furthermore, the amount (g) of the organosilicon surfactant added to the liquid resin composition is preferably 1 to 20% of the amount (g) of titanium dioxide microparticles 113.

[0056] As the organic solvent in the above-mentioned liquid mixture (silicone rubber component + organic solvent), for example, aromatic hydrocarbon solvents such as toluene and xylene, and aliphatic hydrocarbon solvents such as n-hexane, n-heptane, n-octane, isooctane, nonane, decane, undecane, and dodecane can be used alone or in combination of two or more. Alternatively, alcohols such as ethanol and isopropanol, and acetone can also be used.

[0057] (Appearance of the layered structure)

[0058] Furthermore, depending on its application and for design considerations, it is sometimes desirable to make the appearance of the laminated structure 1 as viewed from the surface 11a side of the second layer 11 colorful, or to imbue the laminated structure 1 with text or patterns. For example, when the laminated structure 1 is used as insulation for cables, by making the appearance of the laminated structure 1 various colors, not only can design be improved, but it can also prevent miswiring. In this case, it is possible to incorporate a colorant into the first layer 10, or to print text or patterns on the surface of the second layer 11 side of the first layer 10.

[0059] The inventors have discovered that by making the primary particle size of the titanium oxide microparticles 113 smaller than before, it is possible to achieve a silicone coating that maintains both resistance to ultraviolet light and transparency in the visible light region (high design flexibility). To ensure both resistance to ultraviolet light with wavelengths of 200–380 nm, including UV-A, UV-B, and UV-C, and transparency in the visible light region, the effective average particle size of the titanium oxide microparticles 113 is less than 100 nm. Furthermore, to ensure both resistance to UV-C (200–280 nm) used in sterilization treatments and transparency in the visible light region, the effective average particle size of the titanium oxide microparticles 113 is less than 50 nm. On the other hand, if the average particle size of the titanium oxide microparticles 113 is too small, it is difficult to suppress the aggregation of the titanium oxide microparticles 113; therefore, the average particle size of the titanium oxide microparticles 113 is preferably 30 nm or more.

[0060] Figure 2 (a) is a top view of the printed medium 20 with printed text. Figure 2 (b) Figure 2 (c) represents samples 2A and 2B, on which silicone coatings 21 and 22 are respectively formed on the surface of quartz glass, and are disposed in... Figure 2 Figure (a) shows the state of the text printed on the printing medium 20 through the silicone coatings 21 and 22. Figure 2 The silicone coating 21 of sample 2A shown in (b) is a film in which titanium oxide microparticles with an average particle size of 250 nm are dispersed in silicone rubber as the base material. Figure 2 The silicone coating 22 of sample 2B shown in (c) is a film in which titanium oxide microparticles with an average particle size of 35 nm are dispersed in silicone rubber, which serves as the base material. It should be noted that synthetic quartz glass manufactured by Kenis Corporation was used as the quartz glass. Furthermore, the concentration of titanium oxide microparticles and the film thickness of silicone coatings 21 and 22 are the same in samples 2A and 2B.

[0061] Depend on Figure 2 Sample 2A shown in (b) and Figure 2 As shown in (c), the comparison of sample 2B shows that if the particle size of titanium oxide particles in silicone rubber is reduced, the transparency of the silicone coating in the visible light region becomes higher and turbidity is suppressed, and the visibility of text and patterns printed on printing medium 20 is improved.

[0062] Figure 3This is a graph illustrating an example of the relationship between the average particle size of titanium oxide particles dispersed in the parent material and the transmittance of light at wavelengths of 300 nm, 325 nm, 350 nm, 375 nm, and 400 nm. As shown in the graph, by making the average particle size of the titanium oxide particles less than 100 nm, the transmittance in a predetermined wavelength band in the near-ultraviolet region can be made lower than the transmittance in the visible light region. That is, the transmittance in a predetermined wavelength band in the near-ultraviolet region can be selectively reduced, and the reduction in transparency to the visible light region can be suppressed. Furthermore, the smaller the average particle size of the titanium oxide particles, the shorter the wavelength of light with extremely low transmittance (extremely high shading rate).

[0063] Figure 4 This is a graph showing an example of the relationship between the average particle size of titanium oxide particles dispersed in the substrate and the presence or absence of surfactant and transmittance. It is also a graph showing an example of the relationship between the wavelength of light and transmittance of an organosilicon coating (the second layer 11 of this embodiment) containing titanium oxide particles 113 with an average particle size of 35 nm and an organosilicon surfactant (polyether-modified silicone oil). Furthermore, in... Figure 4 In the comparison, the relationship between light wavelength and transmittance is shown for an organosilicon coating containing titanium dioxide particles 113 with an average particle size of 35 nm but without organosilicon surfactants, and for an organosilicon coating in which the average particle size of titanium dioxide particles 113 is replaced with 250 nm. It should be noted that the film thickness of each organosilicon coating is the same, and the concentrations, average particle sizes, and concentrations (mass%) of other additives (organosilicon resin particles 112 and nano-silica particles 114) and titanium dioxide particles in each organosilicon coating are also the same.

[0064] like Figure 4 As shown in the figure, by setting the average particle size of titanium oxide particles to 35 nm, compared with the case of an average particle size of 250 nm, the transmittance of ultraviolet rays in the UV-A, UV-B, and UV-C bands can be significantly reduced, while the transmittance of light in the visible light region can be increased. Furthermore, by adding an organosilicon-based surfactant, the aggregation of titanium oxide particles 113 is suppressed, and the titanium oxide particles 113 are dispersed, further improving the transmittance of light in the visible light region.

[0065] It should be noted that, in Figure 4 The figure shows the transmittance when the titanium oxide particles contain an organosilicon surfactant and the average particle size is set to 35 nm. However, if the average particle size of the titanium oxide particles is less than 50 nm, the transmittance in the near-ultraviolet region can be reduced compared to the previous case where the average particle size of the titanium oxide particles was 100 nm or more.

[0066] Figure 5(a) is a configuration diagram showing an example of applying the stacked structure 1 of this embodiment to the probe cable 4 of a medical ultrasound probe 3. Figure 5 (b) is Figure 5 A cross-sectional view at line AA in (a). Probe cable 4 is an example of an irradiated object receiving ultraviolet radiation.

[0067] The ultrasound probe 3 is used by clinical laboratory technicians in the diagnosis of patients. It includes a probe cable 4, a probe element 5 at one end of the probe cable 4, and a probe connector 6 at the other end of the probe cable 4. The probe element 5 has an ultrasound transceiver wavefront 5a that is pressed against the patient's body surface. The probe connector 6 is connected to an image forming apparatus that performs ultrasound image formation processing. During the diagnosis of a patient, the clinical laboratory technician presses the ultrasound transceiver wavefront 5a of the probe element 5 against the patient's body surface at various angles, thus causing the probe cable 4 to rub against the patient's body, the clinical laboratory technician's clothing, etc. After the examination, the ultrasound probe 3 is disinfected by irradiation with UV-C light.

[0068] exist Figure 5 In (b), a cross-section perpendicular to the length direction of the probe cable 4 is shown. The probe cable 4 has: a cable core 40 containing a plurality of signal lines 41; a press-wound tape 42 pressed and wound around the outer periphery of the cable core 40; a braided shield 43 covering the outer periphery of the press-wound tape 42; a sheath 44 covering the outer periphery of the braided shield 43; and a silicone coating 45 covering the surface 44a of the sheath 44. The sheath 44 corresponds to the first layer 10 of the aforementioned laminated structure 1, and the silicone coating 45 corresponds to the second layer 11 of the aforementioned laminated structure 1. That is, in the ultrasonic probe 3, the sheath 44 and the silicone coating 45 correspond to the aforementioned laminated structure 1.

[0069] Signal line 41 is a coaxial cable with an inner conductor and an outer conductor. One end connects to the ultrasonic sensor inside the probe 5, and the other end connects to the connector pin of the probe connector 6. Braided shield 43 is constructed by braiding multiple shielding wires 431 into a grid pattern. The outer diameter of the probe cable 4 is, for example, 5 mm or more and 11 mm or less, and the thickness of the sheath 44 is, for example, 0.5 mm or more and 1.5 mm or less. The thickness of the silicone coating 45 is, for example, 3 μm or more and 100 μm or less.

[0070] Silicone rubber, the base material of the sheath 44, has higher UV resistance than polyvinyl chloride. However, it also has a unique sticky feel, sometimes referred to as viscous. If the sheath 44 were not covered by the silicone coating 45, it could snag when the probe cable 4 rubs against the patient's body or the clinician's clothing. The silicone coating 45 covers the entire circumference of the surface 44a along the length of the sheath 44, improving the sliding properties (sliding motion) of the probe cable 4 and enhancing its UV resistance.

[0071] (Effects of the implementation method)

[0072] According to an embodiment of the present invention, the second layer 11 (the silicone coating 45 in the probe cable 4), which serves as the silicone coating film, ensures both resistance to ultraviolet light and transparency in the visible light region. Furthermore, although titanium dioxide particles 113 with smaller particle sizes and easier aggregation than before are used, the sedimentation of the titanium dioxide particles 113 can be suppressed by the nano-silica particles 114, preventing damage to the uniformity of the titanium dioxide particle distribution 113 in the base material 111. Moreover, since the titanium dioxide particles 113 have smaller particle sizes and a larger surface area to volume ratio than before, the same resistance to ultraviolet light can be obtained even with a smaller amount of titanium dioxide particles than before.

[0073] (Summary of Implementation Methods)

[0074] Next, the technical ideas learned from the embodiments described above will be described by reference to the accompanying reference numerals and the like. However, the reference numerals in the following description do not limit the constituent elements in the claims to the components specifically shown in the embodiments.

[0075] [1] An organosilicon coating (11, 45) is a coating (second layer 11, organosilicon coating 45) provided as the surface layer of an irradiated object (probe cable 4) receiving ultraviolet radiation, with silicone rubber as the base material (111) and containing titanium oxide microparticles (113) with an average particle size of less than 100 nm.

[0076] [2] According to the organosilicon coating (11, 45) described above [1], the average particle size of the titanium oxide microparticles (113) is less than 50 nm.

[0077] [3] According to the organosilicon coating (11, 45) described above [1], the average particle size of the titanium oxide microparticles (113) is 30 nm or more.

[0078] [4] The organosilicon coatings (11, 45) described above [1] further contain organosilicon surfactants.

[0079] [5] The organosilicon coating (11, 45) described above [1] further comprises nano-silica particles (114) with an average particle size smaller than that of titanium dioxide particles (113) and organosilicon resin particles (112) with an average particle size of 1 μm or more.

[0080] [6] A laminated structure (1) is a laminated structure (1) on a first layer (10, sheath 44) with silicone rubber as the base material (101) having a second layer (11, 45) laminated on it, wherein the second layer (11, 45) is an organosilicon coating (11, 45) as described in any one of [1] to [5] above.

[0081] [7] A method for manufacturing a laminated structure, comprising: a method for manufacturing a laminated structure (1) on a first layer (10, 44) of a silicone rubber base material (101) and a second layer (111) of a silicone rubber base material (111) containing titanium oxide microparticles (113) with an average particle size of less than 100 nm, comprising: a preparation step of preparing a liquid mixture of the silicone rubber component, which is the silicone rubber component, and an organic solvent, which is the component of the silicone rubber base material (111) that becomes the second layer (11); and a first dispersion step of adding an organosilicon surfactant to the liquid mixture and dispersing the added organosilicon surfactant. The second dispersion step involves further adding the titanium oxide particles (113) to the liquid mixture after the first dispersion step, thereby dispersing the added titanium oxide particles (113); the raw material attachment step involves setting the liquid mixture as a liquid resin composition that serves as the raw material for the second layer (11), thereby attaching the liquid resin composition to the surface of the first layer (10); and the layer formation step involves curing the silicone rubber component by vaporizing the organic solvent contained in the liquid resin composition attached to the surface of the first layer (10), thereby forming the second layer (11).

[0082] [8] The manufacturing method of the laminated structure described in [7] above includes: a third dispersion step, after the second dispersion step, further adding nano-silica particles (114) with an average particle size smaller than the average particle size of the titanium dioxide particles (113) to the liquid mixture, so that the added nano-silica particles (114) are dispersed; and a fourth dispersion step, after the third dispersion step, further adding organosilicon resin particles (112) with an average particle size of 1 μm or more to the liquid mixture, so that the added organosilicon resin particles (112) are dispersed.

[0083] The embodiments of the present invention have been described above, but these embodiments do not limit the invention as defined in the claims. Furthermore, it should be noted that the combinations of features described in the embodiments are not necessarily all necessary for solving the inventive problem.

[0084] Furthermore, the present invention is not limited to the above-described embodiments and can be implemented with appropriate modifications. For example, in the above embodiments, the case where the irradiated object of the present invention is specifically embodied as the probe cable 4 has been described, but the present invention is not limited thereto. In addition to the sheet for constant temperature greenhouses and the sheet for sterilization chambers described above, other irradiated objects such as automotive exterior or interior materials, outdoor products, medical devices other than probe cables, and food processing equipment for ultraviolet sterilization can also be used as irradiated objects. That is, the present invention is not limited to ultraviolet rays contained in sunlight or ultraviolet rays for sterilization emitted from light-emitting elements such as deep ultraviolet LEDs. Various products that are exposed to ultraviolet rays can be used as irradiated objects, and the silicone coating of the present invention is provided as the surface layer of the product to shield ultraviolet light by absorption and / or scattering, thereby improving resistance to ultraviolet light.

Claims

1. An organosilicon coating, which is provided as a surface layer of an object to be irradiated by ultraviolet light. The silicone coating uses silicone rubber as the base material and contains titanium oxide microparticles with an average particle size of less than 100 nm.

2. The organosilicon coating according to claim 1, wherein, The average particle size of the titanium oxide microparticles is less than 50 nm.

3. The organosilicon coating according to claim 1, wherein, The average particle size of the titanium oxide microparticles is greater than 30 nm.

4. The organosilicon coating according to claim 1, further comprising an organosilicon surfactant.

5. The organosilicon coating according to claim 1 further comprises nano-silica particles with an average particle size smaller than the average particle size of the titanium dioxide particles and organosilicon resin particles with an average particle size of 1 μm or more.

6. A laminated structure, wherein a second layer is laminated on a first layer of silicone rubber as the base material. The second layer is the organosilicon coating as described in any one of claims 1 to 5.

7. A method for manufacturing a laminated structure, comprising: a method for manufacturing a laminated structure on a first layer of silicone rubber as the base material, wherein a second layer of silicone rubber as the base material and comprising titanium oxide microparticles with an average particle size of less than 100 nm is laminated thereon; the method comprising: The preparation process involves preparing the silicone rubber components, which will become the base material for the second layer, into a liquid mixture of silicone rubber components and an organic solvent. In the first dispersion step, an organosilicon surfactant is added to the liquid mixture to disperse the added organosilicon surfactant. The second dispersion step involves further adding the titanium oxide particles to the liquid mixture after the first dispersion step, thereby dispersing the added titanium oxide particles. In the raw material attachment process, the liquid mixture is set as a liquid resin composition that serves as the raw material for the second layer, and the liquid resin composition is attached to the surface of the first layer. as well as The layer forming process involves curing the silicone rubber component by vaporizing the organic solvent contained in the liquid resin composition attached to the surface of the first layer, thereby forming the second layer.

8. The method for manufacturing a laminated structure according to claim 7, further comprising: The third dispersion step, following the second dispersion step, involves further adding nano-sized silica particles with an average particle size smaller than that of the titanium dioxide particles to the liquid mixture, thereby dispersing the added nano-sized silica particles; and The fourth dispersion step involves adding silicone resin particles with an average particle size of 1 μm or more to the liquid mixture after the third dispersion step, thereby dispersing the added silicone resin particles.

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