Special receptacle or package – With indicator
Reexamination Certificate
1999-10-18
2001-07-31
Luong, Shian (Department: 3728)
Special receptacle or package
With indicator
C428S035200, C422S028000, C422S051000, C436S135000
Reexamination Certificate
active
06267242
ABSTRACT:
TECHNICAL FIELD
This invention relates to a chemical indicator, in particular, a sheet having a composition layer which is useful in a hydrogen peroxide plasma sterilization treatment, and to a packaging bag for such a plasma sterilization treatment which has said composition layer.
BACKGROUND ART
Since long ago, various kind of sterilization means have been applied to articles of every species such as disposable or recyclable medical apparatuses and food containers, and there have also been proposed indicators for conveniently distinguishing whether such a sterilization treatment has been made or not. For example, Japanese Patent Application Laid-Open (Kokai) No. 36172/1984 discloses an indicator for gas sterilization treatment with use of ethylene oxide; and Japanese Patent Application Laid-Open (Kokai) Nos. 287972/1986, 43827/1993 and 65441/1993 each disclose an indicator ink for electron beam sterilization. The latter group of Laid-Open (Kokai) Applications each mention an indicator wherein a pH indicator is used in combination with such a high molecular compound as is capable of generating hydrogen chloride when irradiated with electron beam.
On the other hand, as a means to conduct a sterilization treatment without adversely affecting medical equipments which are produced from various materials, there have recently been proposed and put into practice a hydrogen peroxide plasma sterilization method and an apparatus therefor (See: Japanese Patent Publication (Kokoku) Nos. 62261/1990 and 22693/1995). This sterilization method summarily comprises a step of contacting an article to be sterilized, with hydrogen peroxide vapor under reduced pressure in an air-tight chamber, and then generating hydrogen peroxide plasma. This method can be said to be a very useful one, not only in that high sterilization efficiency is attained but also in that, when plasma state is ended, hydrogen peroxide is converted into water and oxygen which are quite harmless.
The above-mentioned Japanese Patent Publication (Kokoku) No. 22693/1995 discloses a liquid-dispensing cassette to be used in a plasma sterilization apparatus which cassette is equipped with a cell for containing a hydrogen peroxide solution. It is further disclosed that said dispensing cassette may be equipped with an indicator strip having a color tone with which to detect the leakage of hydrogen peroxide solution from the liquid-containing cell. Said Publication does not concretely disclose, however, how to constitute the indicator strip.
Also in putting a hydrogen peroxide plasma sterilization method into practice, it would be desirable that there should be available such an indicator which can easily distinguish whether or not a sterilization treatment has been given to an article to be sterilized, as is employed in the aforementioned gas sterilization treatment with use of ethylene oxide or electron beam sterilization treatment. Thus, the object of this invention is to provide both a sheet having a chemical indicator composition layer (or an indicator function layer) which can distinguish whether or not a hydrogen peroxide plasma sterilization treatment has been given to an article to be sterilized, and a packaging bag for plasma sterilization having said composition layer.
DISCLOSURE OF INVENTION
The aforementioned Japanese Patent Application Laid-Open (Kokai) No. 65441/1993, for example, suggests that, when bisphenols and a substance such as triphenylsulfonium hexafluorophosphate which generates acid or free radical when irradiated with electron beam are compounded with an indicator ink which comprises a pH indicator and such a high molecular compound as generates hydrogen chloride when irradiated with electron beam, there can be improved the color changeability of said ink when irradiated with electron beam. The inventors of the present invention, on the other hand, have found out that, when a dye belonging to a specific pH indicator is brought into contact with a system which comprises hydrogen peroxide and plasma derived from hydrogen peroxide and which does not generate hydrogen chloride, there occurs a certain color change, which can be both stabilized and rendered distinct when a certain organic amine is made to co-exist.
Thus, in order to achieve the above-mentioned object, this invention provides a sheet used for distinguishing whether a hydrogen peroxide plasma sterilization treatment has been made or not, which sheet has, on its substrate, an indicator composition layer and, under circumstances, an overcoat layer which is provided on said indicator composition layer, the indicator composition layer containing a dye which can change its color when contacted with at least one substance selected from the group consisting of hydrogen peroxide and plasma derived from hydrogen peroxide, an organic amine compound which does not evaporate under ambient conditions, aliphatic alcohol(s) and a synthetic resin which is soluble in said alcohol(s).
This invention which has the aforementioned features makes it possible to clearly distinguish whether medical apparatuses, food containers and the like have undergone or not such a hydrogen peroxide plasma sterilization treatment, even after a certain time has passed from said treatment.
DETAILED DESCRIPTION OF INVENTION
As for the dye, in the indicator composition layer of this invention, which can change its color when contacted with at least one substance selected from the group consisting of hydrogen peroxide and plasma derived from hydrogen peroxide, there can be employed dyes of any kind so long as they make it possible, owing to tr change in color before and after said contact, to clearly distinguish whether such a contact has been made or not. As typical examples of such dyes, there can be taken, not restrictively, pH indicators which have a transition interval in a range of pH 5.5 to 9.0. Concrete examples of such pH indicators include 1,2-dihydroxy anthraquinone (pH 5.5-6.8); dibromothymol sulfonphthalein (Bromothymol Blue: pH 6.0-7.5); 5,8-quinolinequinon-8-hydroxy-5-quinolyl-5-imide (pH 6.0-8.0); 3-amino-6-dimethylamino-2-methylphenazine hydrochloride (pH 6.8-8.0); phenolsulfonphthalein (Phenol Red pH 6.8-8.4); o-cresolsulfon phthalein (Cresol Red: pH 7.2-8.8); m-cresolsulfon phthalein (pH 7.4-9.0) and the like, and tr derivatives. In practical use, two or more of these indicators may be combined with one another.
This invention is characterized in that the above dye is used along with an organic amine compound which does not evaporate under ambient conditions (concretely, at a room temperature at which the sterilization treatment is made). Any kind of such organic amine compounds are usable so long as they do not evaporate throughout sterilization treatment, in particular a low temperature sterilization treatment with use of hydrogen peroxide (See: for example, Japanese Patent Publication (Kokoku) No. 62261/1990; Thus cited, this Publication constitutes a part of the present invention), and so long as they can adjust pH of the composition to alkaline side. Examples of such organic amine compounds include mono higher aliphatic amine such as laurylamine, mono hydroxy higher aliphatic amine, triethanol amine, diethanol amine and monoethanol amine. Among these, triethanol amine is preferably employed in particular, in consideration of compatibility with the dye used in this invention and compatibility with synthetic resin which may be included as vehicle in the composition.
The indicator composition layer of this invention can usually contain a vehicle (including synthetic resin, solvent, and, if necessary, plasticizer as well), which is normally used for the preparation of printing ink, and additive (such as dispersant, stabilizer and thickening agent), and, further, in particular, aliphatic alcohol(s) and a synthetic resin which is soluble in said alcohol(s), for example, polyamide resin.
As for typical example of such synthetic resin, polyamide resin which is normally used for the preparation of printing ink is conveniently employed. As for solvent, isopropyl alcohol, n-prop
Nagata Masanori
Sagara Makoto
Sutoh Teiko
Johnson & Johnson Medical Kabushiki Kaisha
Knobbe Martens Olson & Bear LLP
Luong Shian
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