US 2606654 A
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g- 1952 J. c DAVIS ET AL PACKAGE COMBINED WITH STERILIZATION INDICATOR Filed. April 19, 1945 IN V EN TORS -75se;/;CDaV/s Ralph .K. Cornwall and 'dwm L Hansen fiffarney Patented Aug. 12, 1952 PACKAGE COMBINED WITH STEBILIZATION r -7INDICATOR... Joseph 0. Davis, Scarsdale, N. Y., and Ralph 'r. K. Cornwall and Edwin L. Hansen, Fredericksburg,
Va., assignors, by mesne assignments, to Amer-. ican Viscose Corporation, Wilmington, Del., a
' corporation of Delaware Application April 19, 1945, Serial No. 589,162
This invention relates in general to sterilization and, in particular, to a sterilization'indicator.
In the preparation of articles for medical and surgical use, it is generalynecessary to insure their complete sterilization. The most convenientfa-nd, therefore; the most commonly used method of sterilizing is the application of heat, usually above the boiling point of water. In the manufacturing processes, such as the original manufacture of surgical instruments, it is generall a simple and routine matter to sterilize the products after their manufacture. However, when these instruments are to be used, for example, in a doctors oflice or in a patients bedroom, and must be sterilized before use, an entirely different problem is presented. In this case there is no convenient routine opportunity for sterilization, and there are many chances for confusing sterilized with unsterilized instruments. Accordingly, it is highly desirable to supply some automatic means to indicate clearly whether an article is actually sterile. 7
Blood donor bottles, which are used repeatedly and which must be sterilized between donations, are a typical illustration of the problem. Sterilization is generally accomplished by heating the blood donor bottle with needle and connective tubing attached to 125 C. for about one-half hour. The needle itself is protected, for example, by means of a glass test tube, so that the once sterilized needle is not subsequently contaminated. Until the time of this invention, there has generall been no uniform method for determining whether or not a particular unit has been sterilized. Keeping the sterile and the unsterile units separate has usually been left entirely to the person operating the sterilizing apparatus. In such an arrangement, of course, in spite of the utmost care, there will occasionally be errors, and sometimes a nonsterile unit will become mixed with other sterile units with possibly serious consequences.
It is an object of the present invention to provide a sterilization-indicating pellicle adapted for use on articles, such as medical and surgical supplies and instruments of all types, for holding a plurality of such articles together and indicating their condition with respect to sterility.
According to the present invention, a plurality of articles to be used together and requiring sterilization byheat treatment before such use are held together as a unitary package assembly by a sterilization indicator in the form of a band of a non-fibrous hydrophilic pellicle made of a film- 2 Claims. (01. 2oc -47 forming material which is substantially colorless and sufiused with a heat-convertible dyestuif material, that is, an organic substance which undergoesa color change upon application of heat.
'It will be understood that the' pellicle ma be treated and thereby combined or suffused with the heat-convertible dyestuff in various ways, especially by impregnating or by coating the pellicle with a composition comprising the dyestuff material. More particularly, the band may be made by treating a hydrophilic pellicle with a solution of the heat-convertible dyestuff material evaporating the solvent therefrom at a temperature below that temperature at which the dyestuff changes color, and applying the pellicle to an article to be sterilized, whereupon during sterilization by heat, the dyestuif in the pellicle is converted into a different colored material, thus indicating that sterilization has been effected.
For a more complete understanding of the nature and objects of the present invention, reference should be had to the accompanying drawing in which the figure is a perspective viewof one embodiment of the article in the form of a band applied to a blood donor bottle.
The hydrophilic pellicle used in the invention may be formed from any water-swelling filmforming material such, for example, as regenerated cellulose which may be regenerated from viscose, cuprammonium solutions of cellulose, other inorganic solvent solutions of cellulose, solutions of cellulose in organic solvents, such as quarternary ammonium compounds and the like,
' or formed by deesterifying cellulose esters, or debecomes detached. To prevent this and also indicate that the article is sterilized, the present invention contemplates that the label will be covered with a transparent shrinkable band which will tightly bind the label to the container during sterilization. In this embodiment, either the label or the transparent band may carry the heat-convertible dyestuif. v
The expression heat-convertible dyestuff is 7 intended to include all organic substances which undergo a chemical change resulting in a change in color upon being subjected to a temperature also hydrophilic above room temperature, particularly at a temperature above 100 C. The color change may be (a) from one color to another color, or (b) from colored to colorless, or (c) from colorless to colored. Dyes or -dye intermediates; or derivatives areapreferred. Fugitive dyes/which are color unstable, and either change to another color or become colorless, are satisfactory. Of.
these, dyes which are color unstable inthe ples ence of steam are particularly desirable. Also,
many dye intermediates, particularly the leuco' bases; which are colorless or colored and are transformed into the corresponding dyestuff-by heat, have been found operable. Many dyestufis may be treated with zinc to givecolored or colorless compounds. These derivatives may be transformed to the original dye-by heat. 1 These also may be used. It will be appreciated that where color changes are more effectively ac-.
complished in the presence of an oxidation catalyst, such as sodium or, potassium dichromate,-
or-an oxidation. inhibitorysuch ingredients maybe included with the heat-convertible dyestufi in preparation of'the indicator. Typical operative heat-convertible dyestufis are listed in the following table. The color index number listedrefers to the description of the. dye in Society of Dyers and'Colourists: Colour Index, edited by F. M.Rowe, published by the Society in 1924, at Bradford, England.
. 4 be one of the hydrophilic materials above named with reference to the pellicle, and with organic dyes, the binder may be a lacquer base such, for example, as a synthetic resin or an organic solvent-soluble cellulose derivative. In thisembodimerit the dyestuirand the lacquer base are dissolved in suitable volatile organic solvents to form alacquer. The hydrophilic pellicle is then coated Example I Referring to the figure, there is shown a blood donor unit comprising a glass-container l0 having a screw cap l I through which passes a glass tube l2 closed by a temporary cap 9 and a rubber tube l3 terminatingin a glass connecting tube Hand provided with a clamp I 5. The unit also comprises a glass tube 16 containing the injection needle I! connected to another section of rubber tubing I3 and closed temporarily with a wad 8 of cotton. During sterilization, it is desirable tohold these miscellaneous items together as a unit.
Color Change Color Index No.
Pyrazole. Fast Green GLL Calcocid BordeaurBXL, 5 parts. Oalcocid Yellow MOG, 1 part, Calcocid GreenOGEx, 1 part Sodium Bicarbonate, 93 parts Auramine Cone; Thiofisvine TON-Cone.- Victoria Pure Blue BO Methyl Violet Conc Blue-purple to colorless...
Amphinaphthoquinone. Red to grey -l Methyl Green Green to violet" Iodine Green ,do
Leuco base of Thionine Blue and sodium Colorless to blue.
Leuco base of Toluidine Blue and sodium .do
potassium chromata- Ohrysoidine Brown to colorless N aphthyl Blue-black N d o Pontacyl Sulphon Blue 5R Cone Blue to brown Green to colorless Brown to green Yellow to colorless do Blue to colorless A green dye derived from Pyrazole manufactured by Sandoz Chemical Company The dyestufi may be applied to or incorporated inthe pellicle in any suitable manner, having regard-for the nature of the dyestufi: When the dyestufi is soluble in water or aqueous solutions, the pellicle may be clipped in the. aqueous solution containing the dyestufL'or the solution may be sprayed upon the pellicleor printed and shown in predetermined areas. The treated pellicle is then-subjected to a drying operation, preferably at 'roomtemperature, or inany case, below the conversion temperatureof the particular dyestuffi employed.
When'the dyestuff is insoluble inaqueous-media, it'may be dissolved in an organic solvent and the pellicle treated with such solution. In general, hydrophilic materials will absorb dyestuffs from such organic solutions, but'if the absorption is not sufficient, it may be increased by introducing inthe organic solution of the-,dye a swelling. agent for the particular hydrophilic material employed, such as water, alcohol, the lower aliphatic esters, and the like.
Alternatively, the. dyestufi may be applied to thepellicle incombination with afilm-forming binder. With water soluble dyes, thebinder may This is accomplished by encirclingthe neck 01' the bottle and the various loose articles with a,
common shrinkable band I8 formed ofregenerated cellulose and containing as the heat-convertible dyestufi, for example, PyrazoleFast Green.
The band is preparedby running regenerated cellulosesheets through a water solution of the.
Example II A continuous tubing formed of regenerated cellulosevin the original wet state is. passed into a bath containing 30 per cent aqueous solution of sorbitol. The run of tubing through the bath is sufficiently long to permit the sorbitol solution to saturate the wall of the tubing. From the plasticizing h. e bin w s passed to a. drier in which it is dried until at least the outer surface is free from liquid moisture. The tubing is then passed through a coating bath of the following composition: Urea-aldehyde resin in the solventsoluble stageparts; alkyd resin20 parts; ammonium thiocyanate.05 part; Pontacyl Sulphon Blue 5R conc. (Color Index No. 289)sufilcient amount to give a definite blue tint to the regenerated cellulose; solvent comprising per cent toluene, 5 per cent butyl alcohol, and 5 per cent methyl cellosolve-sufiicient quantities to produce the desired consistency of solution.
From the coating bath, the tubing is passed through a suitable heating chamber where it is quickly heated to from 90 C. to C. for one to two minutes. During this heating, the solvents are evaporated and the urea-aldehyde resin polymerized to a hard form. The coated tubing is then passed to a printing press where it is provided with any desired legend or design. From the printing press, the tubing is passed into a chopper where it is severed into bands. The dry bands are suitable for storage or shipment as such.
The band is conditioned by soaking in water for a period of approximately one hour and then slipped over the neck of a bottle, such as a blood donor unit as described in Example I and allowed to dry. Upon sterilization of the article, the coated band changes in color from blue to brown. Thus, it is easily ascertained which units have been sterilized and which have not.
It will be apparent from the above discussion that this invention has numerous advantages. Chief among these is the prevention of errors during sterilization which would result in the use of unsterilized instruments or apparatus. Also of importance, however, are its low cost and its ease of preparation. It is thus adapted to manufacture by machine operation in quantity. Because of its simplicity, it is completely reliable and is not subject, for example, to breakage, spoiling, mechanical failure, etc.
Since many changes may be made in the process and many different embodiments of the indicator are possible following the principles of the invention, the invention is not to be limited except as indicated by the appended claims.
Having described our invention, what we claim as new and desire to secure by Letters Patent is:
l. A package assembly comprising a plurality of articles to be made sterile before use by heat treatment and a shrunk band extending around the articles and holding them together tightly, band being made of a film-forming material which is substantially colorless and being sufiused with a heat-convertible dyestuff which undergoes a change in color at a temperature between C. and 166 C.
2. An assembly as defined in claim 1 in which the film -forming material is regenerated cellulose.
JOSEPH C. DAVIS. RALPH T. K. CORNNELL. EDWIN L. HANSEN.
REFERENCES CITED The following references are 01. record in the fiie of this patent:
UNITED STATES PATENTS Number Name Date 1,84%,199 Bicknell et al. Feb. 9, 1932 1,894,015 Bernstein Jan. 10, 1933 2,049,867 Richards Aug. 4, 1936 2,118,144 Berman et a1 May 24, 1938 2,222,067 Chaney et a1 Nov. 19, 1940 2,388,087 Lappala Jan. 12, 1943