JPS61287968A - Paint capable of changing its color by radiation - Google Patents

Abstract

PURPOSE:To provide the titled paint which enables easy measurement of radiation dose in a relatively high dose region, by dissolving a resin compsn. contg. a halogen-contg. polymer, a dye and a basic substance in a good solvent for said polymer. CONSTITUTION:A resin compsn. obtd. by blending at least one dye (A) capable of changing its color with changes in pH, selected from among phenolphthalein, Methyl Yellow, Bromothymol Blue, Bromophenol Blue, Thymol Blue and Methyl Red and a basic substance (B) such as NaOH or benzylamine with a polymer 9C) contg. halogen in its molecular structure (e.g. PVC) is dissolved in a good solvent for component C. EFFECT:Radiation dose in a relatively high dose region of 10Mrad or above can be readily measured.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a radiation color-changing paint for simple radiation dose measurement.

(Prior Art) In recent years, industrial use of radiation has spread to a very wide range of industrial fields, including food irradiation, sterilization of medical instruments, and crosslinking of plastics such as electric wires and shrink tubes. When using these types of radiation, it is necessary to measure and manage the radiation dose using a simple method.So far, the dosimeters used have been cellulose triacetate film (CTA) dosimeters, polyethylene terephthalate film (PET) dosimeters, Examples include polymethyl methacrylate (PMMA) dosimeters, polycarbonate dosimeters, blue cellophane dosimeters, and radiochromic dosimeters. Furthermore, there are irradiation discoloration tapes based on polyvinyl chloride.

(Problem to be solved by the invention) However, with dosimeters such as CTA and PETSPMMA1 blue cellophane, it is necessary to measure the absorbance with an ultraviolet absorbance meter after irradiation in order to measure the dose. It's hard to say. On the other hand, PVC color changing tape costs 10 Mrad.
At the following irradiation doses, the discoloration is relatively clear, but when the irradiation dose exceeds 1Q Mrad, the sensitivity of the irradiation dose and discoloration becomes dull, making it effective in relatively low-dose fields such as food irradiation and medical sterilization. However, 1QMr for electric wires, shrink tubes, etc.
It cannot be used in fields where an irradiation dose higher than AD is required.

In view of the above, the present invention was developed to meet the need for simple irradiation dose measurement, particularly in a relatively high dose region of 10 Mrad or more. The present invention will be explained in detail below.

(Means for Solving the Problems) The present invention provides a polymer containing a halogen in its molecular structure.
A resin composition containing dyes and basic substances that change color due to changes in H is dissolved in a good solvent for the polymer, and dispersants, inorganic fillers, etc. are added as necessary, and the color changes when irradiated with radiation. This is a radiation color changing paint that is characterized by:

(Function) As described above, a paint that changes color upon irradiation with radiation can be obtained.

In the above, polymers containing halogens include vinyl chloride resin, vinyl chloride-vinyl acetate copolymer, ethylene-vinyl acetate-vinyl chloride graftomer, chloroprene rubber, chlorosulfonated ethylene rubber, vinylidene chloride resin, These include vinylidene fluoride resin, vinylidene fluoride-propylene hexafluoride copolymer, vinylidene fluoride-ethylene tetrafluoride copolymer, and the like.

Since the polymer is based on a polymer containing a halogen in its molecular structure, the halogen is isolated or hydrogenated by the action of ionizing radiation, resulting in a change in the pH of the system.

Any dye may be used as long as it changes color depending on changes in pH, but in particular dyes selected from the group consisting of phenolphtapurine, methyl yellow, furomothymol blue, fibromophenol blue, thymol blue, and methyl red may be used. By using one dye or a combination of two or more dyes, the color change due to radiation irradiation becomes more noticeable.

Examples of basic substances include hydroxides of alkali metals such as IJium and potassium hydroxide, or benzylamine,
Amines such as isopropylamine, diethylamine, pyridine and the like are suitable.

The purpose of adding a basic substance is to make the discoloration caused by radiation irradiation clearer and to control the irradiation dose-discoloration range. Further, the amount of the basic substance added varies depending on the dye system used and the setting of the irradiation dose and discoloration range.

(Example) Examples will be described below to help understand the present invention.

[Example-1] Adding 10% by weight of a mixed dye of bromothymol blue and bromophenol blue in a weight ratio of 75/25 to polyvinyl chloride resin, and further adding butyl acetate,
The solid content was adjusted to 30% by weight. Add 10% by weight of 1NKOH ethanol solution to the polyvinyl chloride paint.
It was added to produce an irradiation color-changing paint. The irradiation discoloration paint was applied onto a polyester film, and after drying, it was irradiated with 0.4 MeV electron beam at 6, 12, 24, and 36.48 M rad, respectively, and the degree of discoloration was confirmed. As a result, in the unirradiated state, the dark green paint was 6 Mrad - yellow green, 12 Mrad - ocher, and 24 Mrad - yellowish green.
The colors changed to Mrad-yellow, 36Mrad-yellow, and 48Mrad-yellow.

Example 2 - To polyvinyl chloride resin, 10% by weight of a mixed dye of bromophenol blue and methyl yellow with a weight ratio of 50150 was added, and then butyl acetate was added to bring the solid content to 30% by weight. I adjusted it accordingly. To the polyvinyl chloride paint, 5 parts by weight of BuN KOH ethanol solution was added to obtain an irradiation discoloration paint. Thereafter, discoloration by irradiation was observed in the same manner as in Example-1. As a result, unirradiated-dark green, 6-
12M rad-green, 24Mrad-orange, 66
~4BMrad - Discolored to red.

[Example-3] Weight ratio of 50 to vinyl chloride-vinyl acetate copolymer
150, a mixed dye of bromothymol blue and methyl yellow, was added in an amount of 10% by weight, and the solid content was adjusted to 60% by weight with butyl acetate. , 10% by weight of benzylamine was added to the vinyl chloride paint to obtain an irradiation discoloration paint. Thereafter, discoloration by irradiation was examined in the same manner as in Example-1. As a result, unirradiated - green, 6-12M r
ad-yellow, 24Mrad=orange, 36-48Mrad-
It turned red in color.

[Example-4] 10% by weight of a mixed dye of thymol blue and phenolphthalein in a weight ratio of 75/25 was added to polyvinyl chloride resin, and the solid content was adjusted to 30% by weight with butyl acetate. . j-sKoH for the polyvinyl chloride paint
A irradiation discoloration paint was prepared by adding 15% by weight of an ethanol solution.

Thereafter, discoloration by irradiation was examined in the same manner as in Example-1. As a result, unirradiated - ocher color, 6M rad - yellow-orange, 12
Mrad=orange, 24Mrad-red, 36-48M ra
d- The color changed to purple.

[Example-5] Weight ratio of 501 to vinyl chloride-vinyl acetate copolymer
10% by weight of a mixed dye of bromothymol blue and methyl red (No. 50) was added, and the solid content was adjusted to 8% by weight (60%) with methyl ethyl ketone. A 1N KOH ethanol solution was added to the vinyl chloride paint in an amount of 20% by weight to obtain a light-fast discoloration paint. Thereafter, discoloration by irradiation was examined in the same manner as in Example-1. As a result, unirradiated - dark green, 6
-12Mrad-brown, 24-36Mrad-orange, 4
8 Mrad - Discolored to red.

All of the irradiation color-changing paints according to the present invention are 0 to 48 Mra.
It was confirmed that there was a discoloration area within the range of d.

(Effects of the Invention) As described above, according to the coating material of the present invention, it is possible to easily measure the irradiation dose in a relatively high dose region of <10 Mrad or more or in a region lower than that.

Claims (3)

[Claims] (1) A radiation color-changing paint characterized by dissolving a resin composition made by adding a paint that changes color due to pH changes and a basic substance to a polymer containing a halogen in its molecular structure in a good solvent for the polymer. (2) Claims in which the paint that changes color due to changes in pH is one or more selected from the group of phenolphthalein, methyl yellow, bromothymol blue, bromophenol blue, thymol blue, and methyl red. The radiation color changing paint described in item (1). (3) The radiation color changing paint according to claim (1), wherein the basic substance is an alkali metal hydroxide or an amine.