HU212471B - Radiation-indicator - Google Patents

Abstract

The polymer dispersion according to the invention is characterized by 28-44 parts by weight of polyvinylidene chloride, 0.5-8 parts by weight of polyvinyl alcohol, 48-71 parts by weight of water, 0.2-1% by weight of water. contains a fraction of methanil yellow and optionally other additives. ffl HU 212 471 Scope of the description: 4 pages

Description

The present invention relates to a high energy radiation indicator.

With the proliferation of the radiation sterilization process, radiation indicators which, when fixed on the product to be irradiated, indicate that the product has been irradiated, thereby avoiding errors that may result from technical or human error, are becoming increasingly important.

It has long been known that low-molecular-weight materials are cleaved from polymers by high-energy radiation, such as hydrochloride from chlorine-containing polymers or nitrous gases from cellulose nitrate. If, as in the above cases, the cleaving small molecule product is acidic, it is obvious to use these polymers in the presence of an acid base indicator as a radiation indicator. However, these attempts have been unsuccessful for a long time. For example, adding an acid-base indicator to a solution of PVC in a volatile solvent such as tetrahydrofuran and evaporating the solvent produces a film which, although exposed to high energy radiation, changes its color with uncertainty and only after heat treatment. clear signal, and the color will eventually recover.

Progress has been made in the production of radiation indicators by German Patent No. 1,182,359, according to which the polymer film is prepared from an aqueous dispersion of the basic polymer after the addition of an acid-sensitive dye (acid-base indicator). The radiation indicator dispersion can be applied to a paper base with adhesive on the backside, which can be referred to as a self-adhesive radiation indicator title.

The proliferation of the radiation indicator label produced as described above was inhibited by the fact that the polymers used in practice, in particular various copolymers of vinyl chloride, and acid-sensitive dyes such as methyl orange, especially in solid phase, indicate the occurrence or occurrence of slight discoloration of the radiation indicator can be misleading.

A more pronounced color change can be achieved according to Hungarian Patent No. 156,630, where methanol is added as an acid-sensitive dye to a dispersion based on a vinyl chloride copolymer, thereby achieving a yellow to dark purple color change. However, this system can only be effectively used on a hydrophobic basis to control radiation. When applied to paper and similar hydrophilic surfaces, the vinyl chloride-containing vinyl chloride copolymer dispersion provides a colorless coating which is useless for radiation indication. In addition, it has been found that the methanolic yellow mixed with the vinyl chloride copolymer dispersion loses its bright dark purple color after irradiation and regains its original yellow color.

According to our experiments, these disadvantages can be overcome by adding a methanol yellow dye to the aqueous dispersion containing polyvinylidene chloride and polyvinyl alcohol, and then, if desired, applying it to paper, drying it and protecting the colored surface thus obtained from UV radiation. we provide it. The radiation color paper thus produced turns a bright dark purple at a dose of 20-25 kGy and retains this color permanently.

The favorable overall effect of the polyvinylidene chloride-poly (vinyl alcohol) dispersion and the methanol yellow dye as recognized above is also surprising because the methanol yellow (Na-salt of m-aminobenzenesulfosacid azodiphenylamine) is well in water in organic solvents. however, it is poorly soluble; it is unclear how the dye molecules in the aqueous phase interact with polyvinylidene chloride molecules to produce hydrogen chloride upon exposure to radiation. The phenomenon experienced may be related to the fact that the methanyl yellow adsorption indicator also has special absorption properties against certain very small suspended solids. However, polyvinyl alcohol is present in the aqueous phase or at the interface between the phases and can thus influence the adsorption process. It is known that even very small differences in molecular structure with respect to adsorption forces can cause significant differences; based on, among other things, the whole science and practice of chromatography is based on this not yet fully discovered phenomenon. It is not excluded that, in the presence of methanyl yellow polyvinyl alcohol, it is known to bind to polyvinylidene chloride particles suspended in an aqueous medium, while other chlorine-containing polymers such as vinyl chloride copolymer dispersions or for example, in the case of cellulose nitrate, this process does not take place or leads to a similar result.

BACKGROUND OF THE INVENTION The present invention relates to a radiation indicator comprising a polymer dispersion and, optionally, a carrier and a UV lacquer coating. The radiation indicator according to the invention is characterized in that the polymer dispersion has 28-44 parts polyvinylidene chloride, 0.5-8 parts polyvinyl alcohol, 48-71 parts water, 0.2 It contains -1 parts by weight of methanyl yellow and optionally known additives. A preferred embodiment of the above radiation indicator is that it is applied to a self-adhesive back label with a polymer dispersion and coated with a coating of ultraviolet radiation protection. The indicator is applied by gluing it to the object to be irradiated and the indicator then clearly indicating the radiation.

The degree of saponification of the polyvinyl alcohol used in the dispersion may vary; it is preferred to use about 90 wt.% saponified polyvinyl acetate based product.

The following examples illustrate the radiation indicator of the present invention and its preparation.

Example 7

An aqueous dispersion of 30 g of polyvinylidene chloride, 1 g of polyvinyl alcohol (Mowiol 30-88, Hochst, Germany) and 3010 mg of methanol yellow dye, 100 mg of 2-hydroxy 4-methoxybenzophenone with UV protection and 68 g water

HU 212 471 Β is available. The dispersion thus prepared is applied to self-adhesive backing paper so that after drying a coating of 10 g / m ² is obtained. The resulting radiation indicator paper is coated with a UV protective varnish coating at a thickness of 3 g / m ² . The yellow indicator paper becomes bright lilac at 25 kGy radiation and retains this color for many years.

Example 2

All were prepared as in Example 1 except that Breon 576 (B.F. Goodrich, Cleveland, USA) vinyl chloride / vinylidene chloride acrylate copolymer was used as the aqueous polymer dispersion. At a radiation dose of 25 kGy, the resulting radiation indicator will turn purple, but after a few hours it will recover its yellow before irradiation.

Example 3 Nitrolacet is prepared from g of nitrocellulose, 10 g of rosin, 5 g of tricresyl phosphate plasticizer and 65 g of ethyl alcohol, and mixed with 300 mg of methanol yellow dye. The varnish solution is applied to a self-adhesive label. After drying, the yellowish lacquer film turned purple upon exposure to radiation and reaches its full color depth at a dose of 100 kGy. The purple color returns to yellow within 24 hours.

Claims (2)

PATIENT INDIVIDUAL POINTS 1. Radiation indicator, preferably for high energy radiation consisting of a polymer dispersion and optionally a carrier, preferably a paper support, characterized in that the dispersion is 28-44 parts by weight of polyvinylidene chloride, 0.5-8 parts by weight poly (vinyl alcohol), 48-71 parts by weight of water, 0.2-1 parts by weight of methanil yellow dye and optionally known additives. 2. The radiation indicator of claim 1, wherein said polyvinyl alcohol comprises from 88 to 92% by weight of saponified poly (vinyl acetate).