JP2018120016A - Gamma ray-resistant reflection film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a gamma ray-resistant reflection film having resistance to gamma rays.SOLUTION: A gamma ray-resistant reflection film has a reflection film 2 formed on the top of a quartz glass base material 1. The reflection film 2 has a metal reflection layer 22 composed of a metal or alloy with 0.799 V or more of standard electrode potential.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a gamma ray reflective film, and more particularly to a gamma ray reflective film formed on a partial surface of a substrate such as a quartz glass substrate and having resistance to gamma ray irradiation.

  In the medical field, as a standard sterilization method, medical devices are sterilized by gamma irradiation. An example of an optical fiber that can be sterilized by gamma irradiation is described in Patent Document 1. The optical fiber described in Patent Document 1 is coated with a metal in order to suppress diffusion of hydrogen from the hydrogen-containing optical fiber to the outside. The end face of the optical fiber is coated with a metal oxide such as aluminum oxide.

An example of a medical device to be sterilized with gamma rays is an optical probe used for optical coherence tomography (OCT). In OCT, coherent light is emitted laterally from the tip of an optical probe inserted into a patient's body, and reflected light is received to generate a tomographic image in the organ.
Many of the optical probes are covered with a fluororesin tube having high chemical resistance and low friction in order to prevent the organ from being damaged.

JP-A-11-343144

When gamma rays are irradiated to a medical device such as an optical fiber on which a metal reflection film is deposited, the metal reflection film may be altered and a phenomenon that appears to be peeled off (hereinafter referred to as “peeling phenomenon”) may occur. As a result of repeated experiments and studies on the peeling phenomenon, the inventors of the present application have found that this peeling phenomenon occurs only when there is a fluororesin tube or the like covering the medical device. Moreover, when the fluororesin was irradiated with gamma rays, fluoride was detected. Furthermore, when the spectroscopic measurement of the deposit on the part where the metal reflective film was altered was performed, a spectrum having a peak at 158 cm ⁻¹ was observed, similar to the Raman spectrum of aluminum fluoride. From these results, it is considered that the peeling phenomenon is caused by the fact that the fluorine resin is slightly decomposed by gamma ray irradiation and the generated fluorine radicals react with the metal reflecting film.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a gamma ray reflective film having resistance to gamma ray irradiation.

  The anti-gamma ray reflective film according to the present invention includes a reflective film formed on a partial surface of a substrate, and the reflective film is a metal formed of a metal or alloy having a standard electrode potential of 0.799 volts or more. It has a reflective layer.

  The anti-gamma ray reflective film of the present invention has a metal reflective layer formed of a metal or alloy having a standard electrode potential of 0.799 volts or more and a low ionization tendency. By forming the reflection layer with a metal having a low ionization tendency in this way, the reaction between the reflection layer and fluorine radicals generated by gamma ray irradiation can be suppressed, and damage to the reflection film due to gamma ray irradiation can be suppressed.

It is a cross-sectional schematic diagram of the gamma ray resistant reflective film which concerns on embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view of a gamma-resistant reflective film according to the present invention. As shown in the figure, the anti-gamma ray reflective film of this embodiment includes a reflective film 2 formed on the upper surface of a quartz glass substrate 1.

  Further, the quartz glass substrate 1 is covered with a fluororesin tube (not shown). Examples of the fluororesin include, but are not limited to, polytetrafluoroethylene (PTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), and polyvinylidene fluoride (PVDF).

  The quartz glass substrate 1 is preferably composed of a light propagation member such as an optical fiber or a refractive index distribution (Gradient Index, GRIN) lens. The anti-gamma ray reflecting film 2 is preferably formed on the mirror-polished surface of the quartz glass substrate 1, and the anti-gamma ray reflecting film 2 reflects light propagating through the inside of the quartz glass substrate 1. Alternatively, light from the outside may be reflected.

  The reflective film 2 has a laminated structure formed by sequentially depositing an undercoat layer 21, a metal reflective layer 22, a topcoat layer 23, and an overtopcoat layer 24 on the upper surface of the quartz glass substrate 1. Yes.

The undercoat layer 21 is preferably formed of, for example, a deposited film of Al ₂ O _{3 having} a thickness of 100 nm, and has an effect of improving the adhesion between the metal reflective layer 22 and the quartz glass substrate 1.

The topcoat layer 23 is preferably formed of, for example, a 100 nm thick SiO ₂ vapor deposition film, and has an effect as a protective film of the metal reflective layer 22.

Furthermore, the overtop coat layer 24 is preferably formed of, for example, a deposited film of Ti ₃ O _{5 having} a thickness of 50 nm, and has an effect of increasing the amount of reflection of the reflective film 2.

  Here, Table 1 shows a test result of gamma ray resistance when a deposited film having a thickness of 150 nm is formed of various materials as the metal reflective layer 22. In the gamma ray resistance test, 50 kGy of gamma ray was irradiated, and after a high temperature and high humidity test for 6 hours in a chamber having an air temperature of 55 ° C. and a humidity of 95%, the reflection film 2 was observed to evaluate the resistance.

As shown in Table 1 above, when the metal reflective layer 22 is formed as a vapor deposition film of gold (Au) having a standard electrode potential of 1.5 V or silver (Ag) having a standard electrode potential of 0.799 V The reflective film 2 remained clean even after the test.
On the other hand, when the metal reflective layer 22 is formed as a deposited film of copper (Cu) having a standard electrode potential of 0.345 V or tin (Sn) having a standard electrode potential of −0.146 V, the reflection is performed after the test. The peeling phenomenon of the film 2 occurred.

From the above test results, the occurrence of the peeling phenomenon is avoided when the metal reflective layer 22 is formed of a metal having a standard electrode potential of 0.799 volts or more and a low ionization tendency. Therefore, in order to avoid the occurrence of the peeling phenomenon, it is desirable to form the metal reflection layer 22 of the anti-gamma ray reflection film with a metal having a standard electrode potential of 0.799 volts or more.
The metal reflection layer 22 may be formed of an alloy based on gold, silver, palladium, or platinum having a standard electrode potential of 0.799 volts or more.

  Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. For example, in the above-described embodiment, the reflective film 2 having the laminated structure in which the metal reflective layer 22 is sandwiched between the undercoat layer 21, the topcoat layer 23, and the overtopcoat layer 24 has been described. The laminated structure is not limited to this.

  In the above-described embodiment, an example in which a gamma ray reflective film is formed on a quartz glass substrate has been described. However, in the present invention, the material of the substrate is not limited to this, and various materials can be adopted. it can. Further, the form of the substrate is not limited. In particular, the surface of the light propagation member forming the reflective film is not limited to a flat surface, and may be a curved surface.

  The present invention is suitable for application to various medical devices that require sterilization by gamma irradiation, such as optical probes for optical coherence tomography (OCT). The present invention is also suitable for application to equipment used for measurement around a nuclear reactor that is expected to be exposed to gamma rays, and equipment used in outer space.

DESCRIPTION OF SYMBOLS 1 Quartz glass base material 2 Reflective film 21 Undercoat layer 22 Metal reflective layer 23 Topcoat layer 24 Overtopcoat layer

Claims (4)

A reflective film formed on a part of the surface of the substrate;
The said reflection film has a metal reflection layer formed with the metal or alloy which has a standard electrode potential of 0.799 volts or more, The gamma-ray-resistant reflection film characterized by the above-mentioned. The base material is a light propagation member,
2. The anti-gamma ray reflection film according to claim 1, wherein the reflection film reflects light propagating through the light propagation member. The gamma ray reflective film according to claim 1 or 2, wherein at least a part of the substrate is coated with a fluororesin. The said metal reflection layer is a vapor deposition film | membrane of gold | metal | money or silver, The gamma-ray-resistant reflection film as described in any one of Claims 1-3 characterized by the above-mentioned.

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