JP7635645B2 - Laminated structure, cable and tube - Google Patents

Description

The present invention relates to a laminated structure, a cable and a tube.

Conventionally, medical device cables have been known that are made of silicone rubber containing fine particles and have a coating that covers the sheath (see Patent Document 1). Compared to polyvinyl chloride (PVC), which has traditionally been used commonly as a sheath material, silicone rubber has the advantage that it hardly discolors over time, but it tends to have a low surface slipperiness.

The coating of the cable described in Patent Document 1 is made of silicone rubber containing fine particles, and so the surface has irregularities resulting from the fine particles. These irregularities can reduce the contact area when the coating comes into contact with another component, and can increase the slipperiness of the coating surface, i.e., the slipperiness of the cable.

Patent No. 6723489

In recent years, sterilization by irradiation with UV-C light has been attracting attention as a simple, inexpensive, and reliable method of sterilizing cables for medical equipment. However, when sterilizing by irradiation with UV-C light, the cable's resistance to UV-C light becomes an issue. It has been confirmed that even cables with a sheath made of silicone rubber deteriorate when repeatedly irradiated with UV-C light, and that cracks appear in the sheath when the cable is subjected to stress, such as bending the cable.

The object of the present invention is to provide a laminated structure having silicone rubber as a base material, which has excellent resistance to UV-C light, and a cable and a tube equipped with an insulator made of the laminated structure.

In order to solve the _above problems, the present invention provides a silicone rubber - _based ^... The present invention provides a laminated structure in which, when a bending test equivalent to 45 to 50% tensile strength is performed after irradiation with UV-C ultraviolet light of No. ² , ten 1.5 mm × 4.5 mm areas on the surface are observed at a magnification of 50 times using an optical microscope, and cracks are observed in three or less areas.

In addition, the present invention has an object to solve the above-mentioned _problems , and provides a silicone rubber ^- based _... The present invention provides a laminated structure in which, when a bending test equivalent to 45 to 50% tensile strength is performed after irradiation with UV-C ultraviolet light of No. ² , ten 1.5 mm × 4.5 mm areas on the surface are observed at a magnification of 50 times using an optical microscope, and cracks are observed in three or less areas.

In addition, in order to solve the above problems, the present invention provides a laminated structure comprising: a first layer having a silicone rubber base material and containing first _TiO2 fine particles; and a second layer having a silicone rubber base material and containing second TiO2 _fine particles laminated on the first layer, wherein the Ti concentration of the first layer is 0.35 mass% or more and 3.0 mass% or less, and the Ti concentration of the second layer is 1.0 mass% or more and 4.4 mass% or less.

In order to solve the above problems, the present invention also provides a cable or tube equipped with an insulator made of the above laminated structure.

The present invention provides a laminated structure having silicone rubber as a base material, which has excellent resistance to UV-C light, as well as a cable and a tube equipped with an insulator made of the laminated structure.

FIG. 1 is a vertical sectional view of a laminated structure according to a first embodiment of the present invention. FIG. 2 is a graph showing preferred ranges of the Ti concentration in the first layer and the Ti concentration in the second layer. FIG. 3 is a plan view showing a schematic configuration of an ultrasonic probe cable according to a second embodiment of the present invention. 4A and 4B are cross-sectional views in the radial direction of the ultrasonic probe cable taken along the line AA in FIG. 5(a) to (c) are radial cross-sectional views of a medical tube according to a second embodiment of the present invention. 6A and 6B are graphs showing the results of the tensile test of sample B1 and sample B2, respectively. 7A and 7B are graphs showing the results of the tensile test of sample B3 and sample B4, respectively. Fig. 8(a) is a graph showing the relationship between the irradiation time of UV-C light and the stress at break of the substrate for samples B1 to B4, and Fig. 8(b) is a graph showing the relationship between the irradiation time of UV-C light and the elongation at break of the substrate for samples B1 to B4. Fig. 9(a) is a schematic diagram showing a state of a bending test, and Fig. 9(b) is a cross-sectional view of the conductor wire and the sheath piece wound around the conductor wire in the radial direction of the conductor wire. 10(a) and (b) are SEM observation images of the surface and cross section of a sheath piece cut out from sample C6 irradiated with UV-C light at an irradiation energy of 2808 J/ ^cm2 . 11(a) and (b) are SEM observation images of the surface and cross section of a sheath piece cut out from sample C7 irradiated with UV-C light at an irradiation energy of 2808 J/ ^cm2 . FIG. 12 shows typical observation images of the surfaces of the sheath pieces cut out from the samples C1 to C11 after the bending test. 13(a), (b), (c), and (d) are graphs showing the relationship between the irradiation energy of UV-C light and the elongation at break for samples D1, D3, D4, and D7, respectively. 14(a), (b), (c), and (d) are graphs showing the relationship between the irradiation energy of UV-C light and the elongation at break for samples D8, D9, D10, and D11, respectively. 15(a) and (b) are graphs plotting the relationship between the Ti concentration in the first layer and the elongation at break. 16(a) and (b) are observation images of the surfaces of samples C11 and C12, respectively, before the wiping test. 17(a) and (b) are images of the surfaces of samples C11 and C12 after the wiping test, respectively.

First Embodiment
(Configuration of laminated structure)
1 is a vertical cross-sectional view of a laminated structure 1 according to a first embodiment of the present invention. The laminated structure 1 includes a first layer 10 having a silicone rubber base material 101 and containing titanium oxide (TiO ₂ ) fine particles 102, and a second layer 11 having a silicone rubber base material 111 and containing titanium oxide (TiO ₂ ) fine particles 113 laminated on the first layer 10.

The silicone rubber that is the base material of the first layer 10 and the second layer 11 is a type of silicone resin. Silicone rubber has a higher resistance to ultraviolet rays (UV-A light, UV-B light) than polyvinyl chloride, which has traditionally been used as a material for cables and tubes used in medical applications.

The laminated structure 1 can take various forms depending on its application. For example, it is molded into a tubular shape when used as an insulator for cables or tubes, and it is molded into a sheet when used as a highly UV-resistant sheet for constant temperature rooms or as an UV-shielding sheet (UV-shielding curtain) to block UV rays leaking from sterilization rooms, etc.

(Configuration of the second layer)
For example, an addition reaction type silicone rubber coating agent or a condensation reaction type silicone rubber coating agent can be used as the silicone rubber which is the base material 111 of the second layer 11. In particular, it is preferable to use an addition reaction type silicone rubber coating agent from the viewpoints of adhesion to the first layer 10 which has silicone rubber as its base material and abrasion resistance.

In order to obtain good slipperiness and a predetermined wiping resistance on the surface of the laminated structure 1 by the second layer 11, the thickness of the second layer 11 is preferably 3 μm or more. The second layer 11 may be laminated on both sides of the first layer 10. The upper limit of the thickness of the second layer 11 is not particularly limited, but is preferably 100 μm or less from the viewpoints of productivity, high flexibility, and high bendability.

The TiO ₂ fine particles 113 contained in the second layer 11 can block UV-C light by absorbing and/or scattering. Here, UV-C light is ultraviolet light in the wavelength range of 200 to 280 nm. The TiO ₂ fine particles 113 block UV-C light, thereby suppressing deterioration of the silicone rubber base material 111 caused by UV-C light. The TiO ₂ constituting the TiO ₂ fine particles 113 may be any of anatase type, rutile type, and brookite type, or may be a mixture of two or more types. In addition, niobium oxide may be added to titanium oxide to provide stability.

As shown in FIG. 1, the second layer 11 preferably contains fine particles 112 for imparting unevenness to the surface of the second layer 11. When the surface is uneven, the contact area between the second layer 11 and a contact object is smaller than when the surface is flat, and the slipperiness is increased.

The microparticles 112 include, for example, at least one of silicone resin microparticles, silicone rubber microparticles, and silica microparticles. Silicone resin, which has fewer reactive groups (e.g., methyl groups) than silicone rubber, is harder than silicone rubber, and silica, which has no reactive groups, is even harder. In terms of density, silica has the highest density, followed by silicone resin and silicone rubber with the lowest density.

In order to suppress deformation of the surface irregularities of the second layer 11 when it comes into contact with a contacting object, it is preferable that the microparticles 112 have a high hardness. This is because, when a pressing pressure is applied to the surface of the second layer 11 by the contacting object, the higher the hardness of the microparticles 112, the more the deformation of the surface irregularities of the second layer 11 can be suppressed. This makes it possible to suppress an increase in the contact area of the second layer 11 with the contacting object and maintain slipperiness. For this reason, from the viewpoint of suppressing deformation of the surface irregularities of the second layer 11 when it comes into contact with the contacting object, silica microparticles are most preferable as the microparticles 112, and silicone resin microparticles are next most preferable.

On the other hand, as mentioned above, silica has a high density, so silica microparticles tend to settle in the silicone rubber coating agent, which is the base material during the manufacturing process of the second layer 11, and are more difficult to disperse in the silicone rubber coating agent (in the second layer 11) than silicone resin microparticles or silicone rubber microparticles. Therefore, from the viewpoint of increasing the uniformity of dispersion in the silicone rubber coating agent (in the second layer 11), silicone rubber microparticles are most preferable as the microparticles 112, and silicone resin microparticles are next most preferable.

Therefore, in order to maintain the slipperiness of the second layer 11 when it comes into contact with a contact object and to achieve uniform dispersion of the microparticles 112 in the base material 111 made of silicone rubber, it is preferable to use silicone resin microparticles as the microparticles 112.

In addition, the bond energy between atoms in the molecular structure of silicone resin and silica is higher than the bond energy between atoms in the molecular structure of silicone rubber. For this reason, silicone resin and silica are more resistant to UV-C light than silicone rubber.

For example, the C-H bonds present in large quantities in silicone rubber have a bond energy (approximately 4.27 eV) that is smaller than the energy of UV-C light (approximately 6.2 eV), and so the bonds are broken by irradiation with UV-C light, but the Si-O bonds present in large quantities in silicone resin have a bond energy (approximately 6.52 eV) that is greater than the energy of UV-C light, and so the bonds are not broken by irradiation with UV-C light. For this reason, from the standpoint of resistance to UV-C light, it is preferable to use silicone resin microparticles or silica microparticles as the microparticles 112.

The average particle size of the microparticles 112 is, for example, 1 μm or more and 10 μm or less. The concentration (mass %) of the microparticles 112 in the second layer 11 is, for example, 10 mass % or more and 60 mass % or less. Here, the "average particle size" in this specification refers to the particle size measured by a laser diffraction scattering method.

(Configuration of the first layer)
The first layer 10 contains _TiO2 particles 102 for blocking UV-C light by absorbing and/or scattering, similar to the second layer 11 which contains TiO2 particles 113 in order to suppress deterioration due to UV- _C light transmitted through the second layer 11.

As described above, the base material 101 is made of silicone rubber, but when the first layer 10 is used as a sheath material, the base material 101 may be made of silicone rubber to which various common compounding agents such as crosslinking agents, crosslinking catalysts, anti-aging agents, plasticizers, lubricants, fillers, flame retardants, stabilizers, and colorants have been added.

(TiO2 _fine particles)
FIG. 2 is a graph showing a preferred range of the Ti concentration in the first layer 10 containing TiO ₂ particles 102 and the Ti concentration in the second layer 11 containing TiO ₂ particles 113.

As shown in Fig. 2, the Ti concentration in the first layer 10 is preferably 0.35 mass% or more and 3.0 mass% or less. By containing TiO2 _fine particles 102 in a concentration such that the Ti concentration is 0.35 mass% or more in the first layer 10, the cable including the laminated structure 1 as an insulator (sheath and its coating) can be irradiated with UV-C light and then subjected to a tensile test specified in "JIS K6251 (1994)" to maintain a high breaking elongation. A specific method for this tensile test will be described later.

On the other hand, if the first layer 10 contains TiO2 _fine particles 102 with a Ti concentration exceeding 3.0% by mass, the first layer 10 becomes hard, and the flexibility and tear strength of the laminated structure 1 decrease. Therefore, when considering the handleability of a cable or tube when the first layer 10 is used as an insulator for the cable or tube, the Ti concentration in the first layer 10 is preferably 3.0% by mass or less.

2, the Ti concentration in the second layer 11 is preferably 1.0 mass% or more and 4.4 mass% or less. By containing _{TiO2 fine} particles 113 in a concentration that results in a Ti concentration of 1.0 mass% or more in the second layer 11, it is possible to suppress the occurrence of cracks on the surface of the laminated structure 1 that reach the first layer 10 in a bending test equivalent to 45 to 50% tensile strength after irradiation with UV-C light ^of 1404 J/cm2. The method of the bending test and the method of observing the presence or absence of cracks will be described later.

On the other hand, when the second layer 11 contains TiO ₂ fine particles with a Ti concentration exceeding 4.4 mass%, the surface roughness of the second layer 11 increases. When the surface roughness increases, dirt and bacteria are more likely to adhere and are more difficult to remove. In addition, when the second layer 11 contains fine particles 112 such as silicone resin fine particles, if the second layer 11 contains TiO ₂ fine particles with a Ti concentration exceeding 4.4 mass%, the adhesion between the base material 111 made of silicone rubber and the fine particles 112 decreases, the fine particles 112 become more likely to fall off, and the slipperiness of the surface of the second layer 11 decreases. For this reason, the Ti concentration in the second layer 11 is preferably 4.4 mass% or less.

2, it is preferable that the concentration of the TiO ₂ fine particles 113 contained in the second layer 11 is higher than the concentration of the TiO ₂ fine particles 102 contained in the first layer 10, that is, the Ti concentration of the second layer 11 is higher than the Ti concentration of the first layer 10. By making the concentration of the TiO ₂ fine particles 113 in the second layer 11 higher than the concentration of the TiO ₂ fine particles 102 in the first layer 10, UV-C light is effectively absorbed and/or scattered in the second layer 11, deterioration of the first layer 10 due to UV-C light is suppressed, and a decrease in the flexibility and tear strength of the laminated structure 1 can be suppressed.

All Ti in the first layer 10 is contained in TiO2 _fine particles 102, and all Ti in the second layer 11 is contained in TiO2 _fine particles 113. The Ti concentration in the first layer 10 and the Ti concentration in the second layer 11 are determined as average values in a measurement area of 125 μm wide × 95 μm long using an energy dispersive X-ray analyzer (EDS) mounted on a scanning electron microscope (SEM).

Second Embodiment
The second embodiment of the present invention is a cable or tube having an insulator made of the laminated structure 1 according to the first embodiment. As an example, a cable used for a medical ultrasound probe cable will be described below.

Fig. 3 is a plan view showing a schematic configuration of an ultrasonic probe cable 2 according to a second embodiment of the present invention. In the ultrasonic probe cable 2, as shown in Fig. 3, an ultrasonic probe 32 is attached to one end of a cable 20 via a boot 31 that protects the one end. Meanwhile, a connector 33 that is connected to the main body of an ultrasonic imaging device is attached to the other end of the cable 20.

Figure 4 (a) is a radial cross-sectional view of the cable 20 of the ultrasonic probe cable 2. Inside the cable 20, electric wires 21, such as multiple coaxial cables, are stored, and a shield 22, such as a braided shield, is provided to cover the multiple electric wires 21. A sheath 23 is provided to cover the shield 22. Furthermore, in the cable 20, a coating 24 is formed that covers the periphery of the above-mentioned sheath 23 and is in close contact with the sheath 23.

Fig. 4(b) is a radial cross-sectional view of the ultrasonic probe cable 2 cut along the cutting line A-A shown in Fig. 3. As shown in Fig. 4(b), the boot 31 is attached to the coating 24 via an adhesive layer 34 so as to cover the coating 24. The adhesive layer 34 is formed of, for example, a silicone adhesive or an epoxy adhesive. The boot 31 may also be formed of, for example, PVC, silicone rubber, chloroprene rubber, or the like, and preferably contains TiO2 _fine particles 102 for blocking UV-C light or an organic ultraviolet absorbing agent, similar to the first layer 10.

The sheath 23 and coating 24 of the cable 20 are respectively composed of the first layer 10 and the second layer 11 of the laminated structure 1. That is, in the cable 20, the laminated structure 1 is used as the sheath 23 and the coating 24. Note that the _TiO2 particles 102 in the sheath 23 and the particles 112 and _TiO2 particles 113 in the coating 24 are not shown in the figure.

The laminated structure 1, which has excellent resistance to UV-C light, is used as the insulator (sheath 23 and coating 24) of the cable 20, so the cable 20 has excellent resistance to UV-C light. Furthermore, when the second layer 11 of the laminated structure 1 contains fine particles 112, the cable 20 has excellent surface slipperiness, and can suppress snagging caused by the stickiness of the surface of the sheath 23. The thickness of the coating 24 is, for example, 3 μm or more and 100 μm or less.

Furthermore, when the first layer 10 contains TiO2 _fine particles 102 with a Ti concentration of 0.35% by mass or more and 3.0% by mass or less, and the second layer 11 contains TiO2 _fine particles 113 with a Ti concentration of 1.0% by mass or more and 4.4% by mass or less, the elongation at break measured by a tensile test after irradiation of the insulation (sheath 23 and coating 24) of the cable 20 with 1404 J/ ^cm2 UV-C light is 250% or more, and the occurrence of cracks on the surface of the second layer 11 in a bending test equivalent to 45 to 50% tensile after irradiation with 1404 J/ ^cm2 UV-C light can be suppressed. In the laminated structure 1 having the second layer 11 not containing _TiO2 microparticles 102, the elongation at break is 250% or more when not irradiated with UV-C light (see FIG. 7(b)). Therefore, the target was set to have an elongation at break of 250% or more even after irradiation with 1,404 J/ ^cm2 UV-C light.

In addition, when the first layer 10 contains TiO ₂ fine particles 102 with a Ti concentration of 0.35% by mass or more and 3.0% by mass or less, and the second layer 11 contains TiO ₂ fine particles 113 with a Ti concentration of 1.0% by mass or more and 4.4% by mass or less, the elongation at break measured by a tensile test after irradiation of 2808 J/cm ² UV-C light of the insulation (sheath 23 and coating 24) of the cable 20 is 150% or more, and the occurrence of cracks on the surface of the second layer 11 by a bending test equivalent to 45 to 50% tensile after irradiation of 2808 J/cm ² UV-C light can be suppressed. Since the elongation at break required for a general rubber material is 150% or more, it was separately set as a target that the elongation at break is 150% or more even after irradiation of 2808 J/cm ² UV-C light.

If the concentration of TiO ₂ fine particles contained in the first layer 10 is high, the flexibility and tear strength of the first layer 10 may decrease. Therefore, it is preferable to increase the concentration of TiO ₂ fine particles contained in the second layer 11 to block UV-C light in the second layer 11. If the concentration of TiO ₂ fine particles 113 contained in the second layer 11 is higher than the concentration of TiO ₂ fine particles 102 contained in the first layer 10, the deterioration of the first layer 10 due to UV-C light can be suppressed, and the decrease in the flexibility and tear strength of the insulation (sheath 23 and coating 24) of the cable 20 can be suppressed.

Next, an example of a method for manufacturing the ultrasonic probe cable 2 in this embodiment will be described. First, multiple electric wires 21 (e.g., 100 or more electric wires 21) are bundled together. Then, a shield 22 is formed to cover the bundled multiple electric wires 21.

Next, the first layer 10 and the second layer 11 of the laminated structure 1 are formed in order to cover the shield 22, and the sheath 23 and the coating 24 are formed. The sheath 23 is formed, for example, by extrusion molding using an extruder. The coating 24 is formed, for example, by a dipping method, a spray coating method, a roll coating method, or the like. In the dipping method, the ultrasonic probe cable 2 formed up to the sheath 23 is pulled up through a liquid coating material to form the coating 24 on the surface of the sheath 23. This dipping method is superior to the spray coating method and the roll coating method in terms of the uniformity of the thickness of the coating 24 formed.

The liquid coating agent used in the dipping method is a liquid silicone rubber containing fine particles 112 and TiO2 _fine particles 113, and contains an organic solvent. The content of the fine particles 112 and TiO2 _fine particles 113 contained in the coating 24 can be controlled by adjusting the content of the fine particles 112 and TiO2 _fine particles 113 contained in this liquid coating agent. As the 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 kinds. In addition, for example, alcohols such as ethanol and isopropyl alcohol, and acetone can be used.

Below, we will explain the structure of a tube (hollow tube) used for medical purposes such as a catheter, as another example of a cable or tube with an insulator made of the laminated structure 1.

Figures 5(a) to (c) are radial cross-sectional views of a medical tube according to a second embodiment of the present invention. The medical tube 40a shown in Figure 5(a) has an outer coating 42 on the outer surface 41a of the tube body 41. The medical tube 40b shown in Figure 5(b) has an inner coating 43 on the inner surface 41b of the tube body 41. The medical tube 40c shown in Figure 5(c) has an outer coating 42 and an inner coating 43 on the outer surface 41a and inner surface 41b of the tube body 41, respectively.

As exemplified by medical tubes 40a, 40b, and 40c, the tube according to this embodiment includes a tube body 41, an outer coating 42 that covers the outer surface 41a of the tube body 41, an inner coating 43 that covers the inner surface 41b of the tube body 41, or both the outer coating 42 and the inner coating 43.

The tube body 41 of the medical tubes 40a, 40b, and 40c is made of the first layer 10 of the laminated structure 1, and the outer coating 42 and the inner coating 43 are made of the second layer 11 of the laminated structure 1. Therefore, the medical tubes 40a, 40b, and 40c have excellent resistance to UV-C light, just like the cable 20 of the ultrasonic probe cable 2 described above.

In addition, when the second layer 11 of the laminated structure 1 contains the fine particles 112, the inner and outer surfaces have excellent slipperiness, so that when an instrument is inserted into the tube and used, such as in a medical tube such as a catheter, the instrument can be smoothly inserted and removed. In addition, the tube according to this embodiment can be used for tube sets for endoscopic surgical instruments, tube sets for ultrasonic surgical instruments, tubes for blood analyzers, piping inside oxygen concentrators, artificial dialysis blood circuits, artificial heart-lung circuits, endotracheal tubes, etc.

(Effects of the embodiment)
According to the first embodiment, it is possible to provide the laminated structure 1 having excellent resistance to UV-C light. Also, according to the second embodiment, it is possible to provide the ultrasonic probe cable 2 and the medical tubes 40a, 40b, and 40c having excellent resistance to UV-C light by using the laminated structure 1 as an insulator.

(Preparation of laminated structure 1)
Four types of samples (specimens A1 to A4) were prepared to verify the UV-C light shielding effect of the second layer 11 of the laminated structure 1. First, 200 coaxial cables with a diameter of about 0.25 mm were twisted together and covered with a braided wire to prepare a cable core. Next, using an extruder, a sheath material was extruded around the outer periphery of the cable core at a speed of 5 m/min to form a sheath 23 with a thickness of 0.8 mm as the first layer 10 of the laminated structure 1 (cable outer diameter: about 8 mm). Here, the sheath material of the sample A1 was a commonly used PVC. The sheath material of the samples A2 to A4 was a color batch containing titanium oxide (a mixture of "KE-color-W" and "KE-174-U" manufactured by Shin-Etsu Chemical Co., Ltd.). The mixture was mixed so that the Ti concentration analyzed by an energy dispersive X-ray analyzer (EDS) mounted on a scanning electron microscope (SEM) (average value in a measurement area of 125 μm wide × 95 μm long) was 0.12 mass %. Through the steps up to this point, samples A1 and A2 not having the coating 24 as the second layer 11 of the laminate structure 1 were produced.

Next, materials for forming the coating 24 of sample A3 were prepared. An addition reaction type silicone rubber coating agent (product name: SILMARK-TM, manufactured by Shin-Etsu Chemical Co., Ltd.) was prepared as the rubber component that would become the base material 111. In addition, silicone resin fine particles with an average particle size of 5 μm (product name: X-52-1621, manufactured by Shin-Etsu Chemical Co., Ltd.) were prepared as the fine particles 112. 120 parts by mass of the silicone resin fine particles, 600 parts by mass of toluene as a viscosity adjustment solvent, 8 parts by mass of a crosslinking agent (product name: CAT-TM, manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.3 parts by mass of a curing catalyst (product name: CAT-PL-2, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed with 100 parts by mass of this rubber component to prepare a coating solution in which the ratio of the fine particles 112 to the coating 24 was 55% by mass. The content of the microparticles 112 in the coating 24 was calculated on the assumption that the coating agent hardens with almost no mass loss (almost equivalent to the blending mass ratio).

Then, the surface of the sheath 23 provided on the cable core was cleaned. After that, the cable core provided with the sheath 23 was immersed in the above coating solution by dip coating to form a coating film made of silicone rubber on the surface of the sheath. The coating film was then thoroughly dried and cured at a temperature of 150°C to form a coating film 24 having an uneven surface. The coating film 24 of the obtained sample A3 had a thickness of 15 μm. Sample A3 was produced by the above process.

Next, materials for forming the coating 24 of sample A4 were prepared. For the coating 24 of sample A4, in addition to the rubber component as the base material 111 and the silicone resin fine particles as the fine particles 112 that were the same as those used for the coating 24 of sample A3, anatase type TiO ₂ fine particles with an average particle size of 250 nm were prepared as the TiO ₂ fine particles 113. Then, 120 parts by mass of the silicone resin fine particles, TiO ₂ fine particles, 600 parts by mass of toluene as a viscosity adjusting solvent, 8 parts by mass of a crosslinking agent (product name: CAT-TM, manufactured by Shin-Etsu Chemical Co., Ltd.), and 0.3 parts by mass of a curing catalyst (product name: CAT-PL-2, manufactured by Shin-Etsu Chemical Co., Ltd.) were mixed with respect to 100 parts by mass of the rubber component to prepare a coating solution in which the ratio of the fine particles 112 to the coating 24 was 55% by mass and the ratio of the TiO ₂ fine particles 113 to the coating 24 was a predetermined concentration. The concentration of TiO2 _fine particles, which are TiO2 _fine particles 113, was adjusted so that the titanium concentration in the coating 24 (average value in a measurement area of 125 μm wide x 95 μm long) obtained by an energy dispersive X-ray analyzer (EDS) mounted on a scanning electron microscope (SEM) was 0.6 mass%. The content of the fine particles 112 in the coating 24 was calculated on the assumption that the coating agent hardens with almost no mass loss (almost equivalent to the blending mass ratio).

Next, similar to the coating 24 of sample A3, the surface of the sheath 23 was cleaned, a coating was formed by dip coating, and the coating was dried and cured to form a coating 24 having an uneven surface. The thickness of the coating 24 of the obtained sample A4 was 15 μm. Sample A4 was produced by the above process.

(Verification of resistance to UV-C light)
In order to verify the resistance of the laminated structure 1 to UV-C light, tensile tests were carried out on the samples A1 to A4 before and after irradiation with UV-C light. First, the sheaths 23 (sheaths 23 covered with coating 24 in samples A3 and A4) of the cable-shaped samples A1 to A4 prepared by the above method were cut along the length to remove the contents in the sheaths 23 and open the sheaths 23. Then, the opened sheaths 23 were punched out with a No. 6 dumbbell to prepare dumbbell test pieces (thickness 0.8 mm). Here, the dumbbell test pieces formed from the sheaths 23 of samples A1, A2, A3, and A4 (sheaths 23 covered with coating 24 in samples A3 and A4) are referred to as samples B1, B2, B3, and B4, respectively. The configurations of samples B1 to B4 are shown in Table 1 below.

The tensile test was a test specified in "JIS K6251 (1994)" and was carried out on the above samples B1 to B4 under conditions of an environmental temperature of 15 to 35°C, an environmental humidity of 28 to 65 RH%, and atmospheric pressure. The UV-C light irradiation was carried out using a storage cabinet with a germicidal lamp (Daishin Kogyo Co., Ltd. DM-5, Lamp GL-10) under conditions of an internal temperature of 25 to 40°C, an internal humidity of 28 to 65%, an internal pressure of 1 atm (atmospheric pressure), a wavelength of 253.7 nm, an illuminance of 1.3 mW/ ^cm2 , and an irradiation time of 100 hours and 200 hours. The illuminometer used was a UVC-254A manufactured by MK Scientific.

Figure 6(a) is a graph showing the results of the tensile test of sample B1. In Figure 6(a), "unirradiated" shows sample B1 in a state where it was not irradiated with UV-C light, and "irradiated" shows sample B1 after 200 hours of irradiation with UV-C light. As shown in Figure 6(a), the strength (magnitude of stress when the base breaks) and elongation are smaller after irradiation with UV-C light than before irradiation, and it was confirmed that sample B1 deteriorates (changes in properties that make it more likely to break) due to irradiation with UV-C light. In addition, since sample B1 was a gray PVC, it was visually confirmed that a yellowish discoloration occurred due to irradiation with UV-C light. Note that 100% elongation means that the length of the dumbbell test piece has doubled from the original length.

Figure 6(b) is a graph showing the results of the tensile test of sample B2. In Figure 6(b), "unirradiated" indicates sample B2 in a state where it was not irradiated with UV-C light, and "irradiated" indicates sample B2 after 200 hours of irradiation with the above-mentioned UV-C light. As shown in Figure 6(b), the strength and elongation were smaller after irradiation with UV-C light than before irradiation, confirming that sample B2 deteriorated (degenerated) due to irradiation with UV-C light. Note that no discoloration due to irradiation with UV-C light was visually confirmed for sample B2 (white) made of silicone rubber. On the other hand, when compared with the graph in Figure 6(a), it can be seen that the degree of deterioration due to irradiation with UV-C light is greater for silicone rubber than for PVC.

Although sample B2 contains TiO2 _fine particles that absorb UV-C light, it is considered that the TiO2 fine particles have almost no effect on the resistance to UV-C light because the Ti concentration in the sheath 23 is low (0.12% by mass). Also, since sample B2 does not have a coating corresponding to the second layer 11, it has inferior surface slipperiness compared to samples B3 and B4.

Figure 7(a) is a graph showing the results of a tensile test on sample B3. In Figure 7(a), "unirradiated" shows sample B3 in a state where it was not irradiated with UV-C light, and "after irradiation" shows sample B3 after 200 hours of irradiation with the above-mentioned UV-C light. As shown in Figure 7(a), the strength and elongation were smaller after irradiation with UV-C light than before irradiation, confirming that sample B3 deteriorates due to irradiation with UV-C light. Furthermore, like sample B2, sample B3 (white) did not show any visible discoloration due to irradiation with UV-C light.

According to FIG. 7(a), cracks occurred in the coating 24 corresponding to the second layer 11 when the elongation exceeded 50%. The coating 24 of sample B3 contains silicone resin microparticles as the microparticles 112, which have excellent resistance to UV-C light, but it is believed that the silicone rubber in the areas where these silicone resin microparticles are not present deteriorated, causing the cracks.

Figure 7(b) is a graph showing the results of a tensile test on sample B4. In Figure 7(b), "unirradiated" shows sample B4 in a state where it was not irradiated with UV-C light, and "after irradiation" shows sample B4 after 200 hours of irradiation with the above-mentioned UV-C light. As shown in Figure 7(b), the strength and elongation are almost the same before and after irradiation with UV-C light, confirming that deterioration of sample B4 due to irradiation with UV-C light was effectively suppressed. Furthermore, like sample B2, no discoloration due to irradiation with UV-C light was visually confirmed for sample B4 (white).

Comparing the test results of sample B4 with those of sample B3, it can be seen that the TiO2 _fine particles contained in the coating corresponding to the second layer 11 blocked UV-C light, suppressing deterioration.

Figure 8(a) is a graph showing the relationship between the UV-C light irradiation time and the stress at break of the substrate for samples B1 to B4. Also, Figure 8(b) is a graph showing the relationship between the UV-C light irradiation time and the elongation at break of the substrate for samples B1 to B4.

8(a) and (b), sample B3, which does not contain TiO2 _fine particles in the coating corresponding to the second layer 11, shows a decrease in strength and elongation as the irradiation time of UV-C light increases. On the other hand, sample B4, which contains TiO2 _fine particles in the coating corresponding to the second layer 11, shows no change in strength and elongation even if the irradiation time of UV-C light increases. In addition, sample B4 has a lower elongation before irradiation with UV-C light than sample B1, but has a higher elongation after irradiation with UV-C light for 200 hours than sample B1. These results also show that the TiO2 _fine particles contained in the coating of sample B4 can suppress the progression of deterioration caused by UV-C light.

(Preparation of laminated structure 1)
Eleven types of samples (specimens C1 to C11) were prepared to verify the resistance of the laminated structure 1 to UV-C light. All of the samples C1 to C11 have a first layer 10 and a second layer 11, and the first layer 10 contains TiO ₂ particles 102. Among the samples C1 to C11, the samples C1, C6, and C9 do not contain TiO ₂ particles 113 in the second layer 11, and were manufactured using the same process and materials as the sample A3 in the above-mentioned Example 1. In addition, the samples C2 to C5, C7, C8, C10, and C11 contain TiO ₂ particles 113 in the second layer 11 (Ti concentration is 1.5 mass% or 1.9 mass%), and were manufactured using the same process and materials as the sample A4 in the above-mentioned Example 1. The configurations of the sheath 23 and coating 24 of the samples C1 to C11 are shown in Table 2 below. The first layer 10 (sheath 23) had a thickness of 0.8 mm, and the second layer 11 (coating 24) had a thickness of 20 μm.

(Verification of UV-C light resistance)
In order to verify the resistance of the laminated structure 1 to UV-C light from the bending strength, a bending test equivalent to 45 to 50% tensile was carried out on the samples C1 to C11 after irradiation with UV-C light. The UV-C light irradiation was carried out using a storage cabinet with a germicidal lamp (Daishin Kogyo Co., Ltd. DM-5, Lamp GL-10) under the conditions of an internal temperature of 25 to 40°C, an internal humidity of 28 to 65%, an internal pressure of 1 atm (atmospheric pressure), a wavelength of 253.7 nm, an illuminance of 1.3 mW/cm ² , and irradiation times of 200, 300, 400, and 600 hours. The illuminometer used was UVC-254A manufactured by MK Scientific. The bending test was also carried out on the above samples C1 to C11 under the conditions of an environmental temperature of 15 to 35°C, an environmental humidity of 28 to 65 RH%, and atmospheric pressure.

Figure 9(a) is a schematic diagram showing the state of the bending test. The sheath piece 50 is a part of the sheath 23 covered with the coating 24, cut from each of the samples C1 to C11. In the bending test, first, a rectangular sheath piece 50 is cut from each of the samples C1 to C11, and wrapped around a conductor (metal wire) 51 with a radius of 0.5 mm as shown in Figure 9(a), and the overlapping part of the sheath piece 50 is sandwiched and fixed from both sides (fixing device is not shown). Here, the sheath piece 50 is prepared by preparing cable-shaped samples C1 to C11 with a length of 1 m, and cutting out the sheath piece 50 to a size of 12 mm (cable circumferential direction) x 18 mm (cable longitudinal direction) from 10 places at equal intervals along the cable longitudinal direction. Then, the sheath piece 50 is wrapped around the conductor 51 so that the side in the cable longitudinal direction is along the circumferential direction of the conductor 51 and the second layer 11 is located on the outer periphery.

9(b) is a cross-sectional view of the conductor 51 and the sheath piece 50 wound around the conductor 51 in the radial direction of the conductor 51. If the radius of the conductor 51 is r and the thickness of the sheath piece 50 is t, as shown in FIG. 9(b), the longitudinal length of the neutral plane 50a of the sheath piece 50 in the range of an arbitrary angle θ is (r+t/2)·θ, and the longitudinal length of the outer circumferential surface 50b of the sheath piece 50 is (r+t)·θ. Therefore, the longitudinal elongation rate of the outer circumferential surface 50b of the sheath piece 50 wound around the conductor 51 is expressed as {(r+t)·θ-(r+t/2)·θ}/((r+t/2)·θ)×100=t/(2r+t)×100, which is approximately 45% since the radius r of the conductor 51 is 0.5 mm and the thickness t of the sheath piece 50 is 0.82 mm.

A bending test was performed on the sheath pieces 50 cut out from the samples C1 to C11. The surface of the sheath piece 50 during the bending test (when the second layer 11 was stretched by 45 to 50%) was observed at a magnification of 50 times using an optical microscope (Keyence Digital Microscope VHX-1000). As a result, for the sheath pieces 50 of the samples C1, C6, and C9 that did not contain _TiO2 microparticles in the second layer 11, the samples irradiated with UV-C light at an irradiation energy of 936 J/ ^cm2 (illuminance (W/ ^cm2 ) x irradiation time (seconds)) did not have cracks on the surface, but the samples irradiated with UV-C light at irradiation energies of 1404 J/ ^cm2 , 1872 J/ ^cm2 , and 2808 J/ ^cm2 had cracks on the surface.

On the other hand, for the sheath pieces 50 cut out from the samples C2 to C5, C7, C8, C10, and C11 containing _TiO2 particles in the second layer 11, no cracks were generated on the surface of any of the samples irradiated with UV-C light at irradiation energies of ⁹³⁶ J/cm ² , 1404 J/cm ² , 1872 J/cm 2, and 2808 J/cm ^2. Note that the cracks referred to in this bending test refer to recesses that reach from the second layer 11 (coating 24) to the first layer 10 (sheath 23).

10(a) and (b) are SEM observation images of the surface and cross section of a sheath piece 50 cut out from a sample C6 irradiated with UV-C light at an irradiation energy of 2808 J/cm ^2. FIG. 11(a) and (b) are SEM observation images of the surface and cross section of a sheath piece 50 cut out from a sample C7 irradiated with UV-C light at an irradiation energy of 2808 J/cm ^2. In the SEM observation images of FIG. 10(a) and (b), a crack 52 is observed that reaches from the second layer 11 to the first layer 10. On the other hand, the recessed portion 53 observed in the SEM observation images of FIG. 11(a) and (b) does not reach the first layer 10, and is not counted as a crack. FIG. 10(a) and FIG. 11(a) are SEM observation images at 100 times magnification, and FIG. 10(b) and FIG. 11(b) are SEM observation images at 1000 times magnification. 13 is an SEM image of the sheath piece 50 removed from the conductor 51 after the bending test.

The results of this bending test were used as one of the conditions for determining whether the laminated structure 1 was resistant to UV-C light. Sheath pieces 50 were taken from 10 locations on each sample that had been irradiated with UV-C light. The bending test was carried out on each of these 10 sheath pieces 50, and the number of sheath pieces 50 in which cracks were observed when a 1.5 mm x 4.5 mm area was observed at 50x magnification using an optical microscope was counted. When 10 1.5 mm x 4.5 mm areas on the surface of the sample were observed, if cracks were observed in 3 or fewer of the 10 1.5 mm x 4.5 mm areas, the laminated structure 1 was determined to be resistant to UV-C light.

Fig. 12 is a typical observation image of the surface of the sheath piece 50 when a bending test was performed on the sheath piece 50 cut out from the samples C1 to C11. The observation image in Fig. 12 is an image of an area of 1.5 mm x 4.5 mm on the surface of the sheath piece 50 made from the samples C1 to C11, observed at a magnification of 50 times using an optical microscope (Keyence Digital Microscope VHX-1000). According to Fig. 12, cracks are observed on the surface of the sheath piece 50 of the samples ^C1 , ^C6 , and ^C9 , which do not contain TiO2 _fine particles in the second layer 11 and are irradiated with UV-C light at irradiation energies (illuminance (W/ ^cm2 ) x irradiation time (seconds)) of 1404 J/cm2, 1872 J/cm2, and 2808 J/cm2. Regarding the sheath pieces 50 cut out from samples C2 to C5, C7, C8, C10, and C11 containing _TiO2 microparticles in the second layer 11, no cracks were observed on the surface of any of the samples irradiated with UV-C light at irradiation energies of 936 J/ ^cm2 , 1404 J/ ^cm2 , 1872 J/ ^cm2 , and 2808 J/ ^cm2 .

For example, in samples C10 and C11 after irradiation with an energy of 2808 J/cm ² , a stripe-like pattern is observed along the longitudinal direction of the sample. This pattern does not reach the sheath 23, and is a recess that appears only in the coating 24. That is, the thickness of the coating 24 is greater than the depth of the recess. Since such a recess does not become the starting point of the breakage of the sheath 23, it is not counted as a crack, as described above. Whether the stripe-like pattern is a crack can also be determined by whether the pattern reaches the sheath 23 using cross-sectional SEM observation images such as those shown in FIG. 10(b) and FIG. 11(b).

From the results of FIG. 12, for samples C2 to C5, C7, C8, C10, and C11, cracks were observed in 3 or less out of 10 1.5 mm x 4.5 mm regions (specifically, 0 (no cracks)), and these samples were determined to have resistance to UV-C light. Also, for samples C1, C6, and C9, cracks were observed in 4 or more out of 10 1.5 mm x 4.5 mm regions, and these samples were determined to have no resistance to UV-C light. From the above, it was found that increasing the content of TiO ₂ fine particles in the second layer 11 is effective in suppressing cracks in the laminated structure 1. Specifically, it was confirmed that cracks in the laminated structure 1 can be suppressed by setting the Ti concentration in the second layer 11 to 1.0 mass% or more.

Next, in order to verify the resistance of the laminated structure 1 to UV-C light from the elongation at break, tensile tests were carried out on the samples C1 to C5 and C7 to C11 after irradiation with UV-C light. UV-C light irradiation was carried out using a storage cabinet with a germicidal lamp (Daishin Kogyo Co., Ltd. DM-5, Lamp GL-10) under the following conditions: temperature inside the cabinet: 25 to 40°C, humidity inside the cabinet: 28 to 65%, pressure inside the cabinet: 1 atm (atmospheric pressure), wavelength: 253.7 nm, illuminance: 1.3 mW/cm ² , and irradiation times: 100, 200, 300, 400, and 600 hours.

After irradiation with UV-C light, dumbbell test pieces D1-D5 and D7-D11 were formed from cable-shaped samples C1-C5 and C7-C11, respectively, in the same manner as in forming samples B1-B4 from samples A1-A4 in Example 1 above. Tensile tests for samples D1-D5 and D7-D11 (6-size dumbbell test pieces) were performed according to the test prescribed in "JIS K6251 (1994)" using the same method and conditions as those performed for samples B1-B4 above. The environmental temperature at the tensile test evaluation location was 25±3°C, the environmental humidity was 50±10%, and the pressure was atmospheric. The gauge length was 20 mm, and the tensile speed was 500 mm/min until breakage.

Figures 13(a), (b), (c), and (d) are graphs showing the relationship between UV-C light irradiation energy (illuminance (W/cm ² ) × irradiation time (sec)) and elongation at break for samples D1, D3, D4, and D7, respectively. Figures 14(a), (b), (c), and (d) are graphs showing the relationship between UV-C light irradiation energy and elongation at break for samples D8, D9, D10, and D11, respectively. Table 3 below shows the numerical values of the plotted points in Figures 13(a), (b), (c), and (d) and Figures 14(a), (b), (c), and (d), i.e., the elongation at break (%) for each sample for each UV-C light irradiation energy.

13(a) to (d), 14(a) to (d), and Table 3 show that, among the elongations at break of samples D1, D3, D4, and D7 to D11, the elongations at break of samples D7 to D11 are 250% or more even when the irradiation energy of UV-C light is 1404 J/cm ² , and samples D7 to D11 have high resistance to UV-C light from the viewpoint of elongation at break. Also, among the elongations at break of samples D1, D3, D4, and D7 to D11, the elongations at break of samples D7 to D11 are 200% or more even when the irradiation energy of UV-C light is 1872 J/cm ² , and samples D7 to D11 have high resistance to UV-C light from the viewpoint of elongation at break. Furthermore, among the elongations at break of samples D1, D3, D4, and D7 to D11, the elongations at break of samples D7 to D11 were 150% or more even when the irradiation energy of UV-C light was 2808 J/ ^cm2 , which shows that samples D7 to D11 have high resistance to UV-C light in terms of elongation at break.

From the results of Figures 13(a) to (d), Figures 14(a) to (d), and Table 3, it was found that in order to increase the elongation at break of the laminated structure 1, it is effective to increase the content of TiO ₂ fine particles in the first layer 10. In addition, as shown in Figures 15(a) and 15(b), the relationship between the Ti concentration (content of TiO ₂ fine particles) in the first layer 10 and the elongation at break (results of D3, D7, and D10, and results of D4, D8, and D11) was plotted and polynomial approximation was performed. Figure 15(a) shows the result after irradiation with 1404 J/cm ² UV-C light, and Figure 15(b) shows the result after irradiation with 2808 J/cm ² UV-C light. It was found that in order to achieve an elongation at break of 250% or more even after irradiation with 1404 J/ ^cm2 UV-C light, the Ti concentration in the first layer 10 should be 0.4 mass% or more. It was also found that in order to achieve an elongation at break of 150% or more even after irradiation with 2808 J/ ^cm2 UV-C light, the Ti concentration in the first layer 10 should be 0.35 mass% or more.

Next, a surface wiping test was carried out on sample C11, which contains TiO ₂ fine particles 113 in the second layer 11, which is the coating 24, with a Ti concentration of 1.9 mass%, and a sample (specimen C12) which contains TiO ₂ fine particles 113 in the second layer 11 with a Ti concentration of 4.4 mass%, which was produced in the same manner as sample C11. The sample for this wiping test was produced and tested in the same manner as in Japanese Patent No. 6723489. In addition, the sample for measuring the static friction coefficient before and after the wiping test was also produced and measured in the same manner as in Japanese Patent No. 6723489. The environmental temperature at the wiping test location and the static friction coefficient measurement location was 25±3°C, the environmental humidity was 50±10%, and the atmospheric pressure.

In this wiping test, a long fiber nonwoven fabric (50 mm long in the wiping direction) made of cotton linters containing rubbing alcohol was placed in contact with the surface of the coating 24 so that a shear stress of 2×10 ⁻³ MPa to 4×10 ⁻³ MPa was applied, and the surface of the coating 24 was wiped 20,000 times (10,000 reciprocating strokes) at a length of 150 mm in the wiping direction and a speed of 80 times/min to 120 times/min. As a result, the difference (absolute value) between before and after the test in the static friction coefficient of the coating 24 of samples C11 and C12 was 0.019 and 0.047, respectively, both of which were less than 0.1. The measured values of the static friction coefficient of the coating 24 of samples C11 and C12 are shown in Table 4 below.

On the other hand, when the surface condition of samples C11 and C12 was observed by SEM before and after the wiping test, differences were found between the two.

Figures 16(a) and (b) are observation images (1000x) of the surfaces of samples C11 and C12 before the wiping test, respectively. Figures 17(a) and (b) are observation images of the surfaces of samples C11 and C12 after the wiping test, respectively. The spherical particles and the white powder particles around them observed in the observation images of Figures 16(a), (b) and 17(a), (b) are fine particles 112 and TiO2 _fine particles 113, respectively.

As shown in Figures 16(a) and 16(b), more voids were observed in the coating 24 of sample C10 than in the coating 24 of sample C11. Also, as shown in Figures 17(a) and 17(b), more particles 112 fell off in the coating 24 of sample C12 than in the coating 24 of sample C11. One of the major causes of these results is thought to be that the concentration of TiO ₂ particles 113 in the coating 24 (second layer 11) of sample C12 was too high. It is thought that more TiO ₂ particles 113 were present around the particles 112, which reduced the contact area between the base material 111 made of silicone rubber and the particles 112, resulting in a decrease in adhesion. From the results of the wiping test and SEM observation, it was confirmed that the upper limit of the Ti concentration in the coating 24 was 4.4 mass%.

The preferred ranges of the Ti concentration in the first layer 10 containing the _TiO2 particles 102 and the Ti concentration in the second layer 11 containing the _TiO2 particles 113, which were explained in the first embodiment with reference to FIG. 2, were derived based on the test results of this example.

(Summary of the embodiment)
Next, the technical ideas grasped from the above-described embodiment will be described by using the reference numerals and the like in the embodiment. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiment.

[1] A first layer (10 ) having a silicone rubber base material (101) and containing first TiO ₂ fine particles (102), and a second layer (11) having a silicone rubber base material (111) and containing second TiO ₂ fine particles (113) laminated on the first layer (10), wherein the Ti concentration of the first layer (10) is 0.35% by mass or more and 3.0% by mass or less, the Ti concentration of the second layer (11) is 1.0% by mass or more and 4.4% by mass or less, the Ti concentration of the second layer (11) is higher than the Ti concentration of the first layer (10), the elongation at break measured by a tensile test after irradiation with 1404 J/cm ² UV-C light is 250% or more, and the 1404 J/cm The laminated structure (1) has a surface that is exposed to UV-C ultraviolet light of No. ² and then subjected to a bending test equivalent to a tensile strength of 45 to 50%, and when ten areas of 1.5 mm x 4.5 mm on the surface are observed at a magnification of 50 times using an optical microscope, the number of areas in which cracks are observed is three or less.

[2] A first layer (10 ) having a silicone rubber base material (101) and containing first TiO ₂ fine particles (102), and a second layer (11) having a silicone rubber base material (111) and containing second TiO ₂ fine particles (113) laminated on the first layer (10), wherein the Ti concentration of the first layer (10) is 0.35% by mass or more and 3.0% by mass or less, the Ti concentration of the second layer (11) is 1.0% by mass or more and 4.4% by mass or less, the Ti concentration of the second layer (11) is higher than the Ti concentration of the first layer (10), the elongation at break measured by a tensile test after irradiation with 2808 J/cm ² UV-C light is 150% or more, and the 2808 J/cm The laminated structure (1) has a surface that is exposed to UV-C ultraviolet light of No. ² and then subjected to a bending test equivalent to a tensile strength of 45 to 50%, and when ten areas of 1.5 mm x 4.5 mm on the surface are observed at a magnification of 50 times using an optical microscope, the number of areas in which cracks are observed is three or less.

[5] The laminated structure (1) according to the above [ 1 ] or [ 2 ], wherein the second layer (11) contains at least one of silicone resin fine particles and silica fine particles.

[6] A cable (20) comprising an insulator (23, 24) made of the laminated structure (1) according to any one of the above [ 1 ] to [ 3 ].

[7] A tube (40a, 40b, 40c) comprising an insulator (41, 42, 43) made of the laminated structure (1) according to any one of the above [ 1 ] to [ 3 ].

Although the embodiments and examples of the present invention have been described above, the present invention is not limited to the above embodiments and examples, and various modifications are possible within the scope of the gist of the invention. Furthermore, the embodiments and examples described above do not limit the invention related to the claims. It should also be noted that not all of the combinations of features described in the embodiments and examples are necessarily essential to the means for solving the problems of the invention.

REFERENCE SIGNS LIST 1 Laminated structure 10 First layer 101 Base material 102 _TiO2 particles 11 Second layer 111 Base material 112 Particles 113 _TiO2 particles 2 Ultrasonic probe cable 20 Cable 23 Sheath 24 Coating 40a, 40b, 40c Medical tube 41 Tube body 42 Outer coating 43 Inner coating

Claims (5)

A first layer having a silicone rubber base material and containing first TiO2 _particles ;
A second layer, laminated on the first layer, the second layer having a silicone rubber base material and containing second TiO2 particles _;
Equipped with
The Ti concentration of the first layer is 0.35 mass % or more and 3.0 mass % or less,
The Ti concentration of the second layer is 1.0 mass % or more and 4.4 mass % or less,
the second layer has a higher Ti concentration than the first layer;
The elongation at break measured by a tensile test after irradiation with 1404 J/ ^cm2 UV-C light is 250% or more,
When a bending test equivalent to 45 to 50% tensile strength is performed after irradiation with the 1404 J/ ^cm2 UV-C ultraviolet rays, when 10 1.5 mm x 4.5 mm areas on the surface are observed at a magnification of 50 times using an optical microscope, cracks are observed in 3 or less areas.
Laminated structure. A first layer having a silicone rubber base material and containing first TiO2 _particles ;
A second layer, laminated on the first layer, the second layer having a silicone rubber base material and containing second TiO2 particles _;
Equipped with
The Ti concentration of the first layer is 0.35 mass % or more and 3.0 mass % or less,
The Ti concentration of the second layer is 1.0 mass % or more and 4.4 mass % or less,
the second layer has a higher Ti concentration than the first layer;
The elongation at break measured by a tensile test after irradiation with 2808 J/ ^cm2 UV-C light is 150% or more,
When a bending test equivalent to 45 to 50% tensile strength is performed after irradiation with the 2808 J/ ^cm2 UV-C ultraviolet rays, when 10 1.5 mm x 4.5 mm areas on the surface are observed at a magnification of 50 times using an optical microscope, cracks are observed in 3 or less areas.
Laminated structure. the second layer comprises at least one of silicone resin particulates and silica particulates;
The laminated structure according to claim 1 or 2 . An insulating material comprising the laminated structure according to any one of claims 1 to 3 .
cable. An insulating material comprising the laminated structure according to any one of claims 1 to 3 .
tube.

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