US 3923154 A
A sterilant package includes paper containing a compound having at least one - CH2OR group wherein R is alkyl, in particular the compound is hexamethoxymethylmelamine. The compound is capable of releasing formaldehyde, upon heating, and is used to sterilize an article in the package.
Claims available in
Description (OCR text may contain errors)
United States Patent Tulis et a1.
Dec. 2, 1975 3,293,062 12/1966 Skofronick ct a1 117/155 R 3,443,979 5/1969- Skofronick 117/37 R 3,469,002 9/1969 Moyer, Jr. et a1. 1. 424/334 3,625,353 12/1971 lshii 206/365 3,630,348 12/1971 Benson ct a1. 206/210 Primary Examiner-William T. Dixson, Jr. Attorney, Agent, or FirmMarn & Jangarathis  ABSTRACT A sterilant package includes paper containing a compound having at least one CH OR group wherein R is alkyl, in particular the compound is hexamethoxymethylmelamine. The compound is capable of releasing formaldehyde, upon heating, and is used to sterilize an article in the package.
8 Claims, N0 Drawings U.S. Patent Dec. 2, 1975 STERILANT PACKAGE This invention relates to a package, and more particularly, to a new and improved package for sterilizing articles.
In recent years there has been an increased interest in sterilizing packages which have incorporated therein a sterilizing agent. In this manner, a sterilized article may be directly removed from the package, without a sterilizing treatment, immediately prior to use thereof.
US. Pat. No. 3,630,348 discloses a sterilizing package having a paper wall which includes a thermosetting resin having methylol groups which are capable of releasing free formaldehyde. In such a package, special precautions must be taken to prevent curing of the resin, which derogates from the ability to release free formaldehyde, and/or prevent premature release of formaldehyde. Accordingly, there is a need for improvements in sterilizing packages.
The principle object of the present invention is to provide a new and improved sterilizing package.
In accordance with the present invention, there is provided a package which includes paper containing a compound having at least one CI-l -OR group capable of releasing free formaldehyde upon heating wherein R is alkyl, preferably lower alkyl (1 to 6 carbon atoms) and most preferably R is methyl.
The drawing is .a simplified schematic diagram of an embodiment of a package of the present invention.
Referring to the drawing, there is shown a sterilant package 10, including an article to be sterilized l2 and paper ll containing a sterilizing amount of hexamethoxymethylmelamine. The paper contains the compound in a manner such that the compound is either internally incorporated therein or coated thereon. The compound is preferably internally incorporated within the paper.
The paper includes a sterilizing amount of the compound, and in general, the paper includes an amount of the compound sufficient to provide in or on the paper from about 0.1 to about 20 by weight, of formaldehyde (CI-I and preferably from about 1 to about 7 by weight, of formaldehyde. It is to be understood, however, that greater amounts could be used, but in general, the use of greater amounts does not have any beneficial effect. Similarly, lower amounts could also be used in certain applications. The choice of the optimum amount of compound to be incorporated into or onto the paper is deemed to be within the scope of those skilled in the art from the teachings herein.
The specific amount of the compound to be added to the paper will vary with the free formaldehyde content of the compound with the compound being added to the paper in an amount to provide the desired formaldehyde content. In general, the compound is added to the paper in an amount from about 0.3% to about 60 by weight, and preferably, in an amount from about 3 to about 20 by weight.
In accordance with the preferred aspect of the present invention, the compound containing the CH OR group(s) is incorporated internally into the paper during the paper making process. The compound is most conveniently added to the paper as an aqueous solution at the size press of the paper machine. In general, the aqueous solution includes from about 5 to about 90 of the compound. The incorporation of the compound into the paper during the paper making opera- 2 tion at the size press or during another portion of the paper making operation is deemed to be within the scope of those skilled in the art.
Alternatively, as hereinabove described, the compound may be coated onto the paper subsequent to the paper making operation by any conventional coating operation, such as, air knife, wire rod, etc.
The preferred compound for addition to the paper is hexamethoxymethylmelamine. The compound has been found to provide excellent sterilizing properties. In addition, a sterilant package including paper containing hexamethoxymethylmelamine is prepared without undue premature releasing of formaldehyde. In addition, the formaldehyde may be released without destruction of the paper substrate. Furthermore, the hexamethoxymethylmelamine may be added to the paper without special precautions; i.e., the sterilizing ability of the compound is not diminished under the conditions normally encountered in a paper making process.
The paper including the compound having at least one -Cl-I OR group, preferably the paper includes hexamethoxymethylmelamine, is employed in the production of a sterilant package. The paper may be incorporated into a vapor-proof package, such as an aluminum foil package or a poylester package, either as a separate piece within the package or as an integral part of the package; e.g., as the inner wall surface of the package, in which case, the vapor proof barrier forms the outer wall surface of the package. In the case where the paper including, for example, hexamethoxymethylmelamine, is employed as a separate piece in the package, the paper may be employed as an inner sleeve or lining or as a wrapping for the article to be sterilized which is in the package.
Alternatively, the outer surface of the package may be comprised of a material having a low-vapor transmission level, such as, polyethylene, polypropylene, polyvinylidene, chloride, etc. In this manner, the formaldehyde released from the hexamethoxymethymelamine, within the package, may be eventually dissipated into the atmosphere, prior to opening of the package. The paper containing the hexamethoxymethylmelamine may be an integral part of the package; i.e., forming the internal wall surface or portion thereof, of the package, or may be present as a separate sheet within the package; e.g., as a wrapping for the article to be sterilized which is placed within the package.
The package, including the article to be sterilized and the paper containing hexamethoxymethylmelamine may be formed and assembled as known in the art. The assembled package is then heated for a time and at a temperature sufficient to effect sterilization of the article by release of formaldehyde from the hexamethoxymethylamine. The time required for such sterilization is inversely related to the temperature, with lower temperature requiring longer times. In addition, the timetemperature relationship is dependent on the amount of formaldehyde incorporated into the vapor. In general, the package is heated to a temperature of at least F. and below the char point of the paper most generally, the sterilization temperature ranges from about 1 10F. to about 260F. and, preferably the sterilization temperature is from about F. to about 210F. The time required for effecting sterilization is generally in the order of 1 second to 24 hours and most generally in the order of 1 hour to 16 hours, with the shorter times corresponding to the higher sterilization temperatures. It should be apparent that longer times could be em- 3 ployed, but generally such longer times have no beneficial effect. The choice of optimum times and temperatures is deemed to be within the scope of those skilled in the art from the teachings herein.
The invention will be further described with respect to the following examples, but it is to be understood that the scope of the invention is not to be limited thereby. Unless otherwise specified, all parts and percentages are by weight.
In the following Examples I and II, sterilizing capacity is tested using bacterial spores as test organisms. Bacillus globigii (l X and l X 10 spores on aluminium and paper are used in the test. After sterilization, the biological spore strips are assayed for viability in trypticase soy broth (TSB). The TSB tubes are examined for B. globigii growth over a period of four days of 37C. incubation. Tubes showing no biological growth are inoculated with viable spores to assure that no bacteriostatic conditions existed and that the broth supported microbial growth.
The sheet of paper, in standard surgical grade, is impregnated with a 8% aqueous solution of hexamethoxymethylmelamine (CYMEL 301) containing ethanol, through a size press at 135F. temperature and the paper dried rapidly, (in the order of l to 2 minutes), in an oven maintained at 2002l5F. The paper is prepared to have various amounts of the CYMEL 301 as expressed in the amount of available formaldehyde.
Two strips of paper prepared as above (2% inches X Aainches) are sealed in a gas tight foil package with the biological spore strips placed between the two strips of paper. The package is placed in hot air incubators or ovens as hereinafter reported.
EXAMPLE III The hexamethoxymethylmelamine impregnated paper (containing 1.42% formaldehyde) is wrapped around the following items, with the spore strip being within the wrapping. The wrapping is sealed in a polyester (MYLAR) bag. The resulting package is heated at 90C. for three hours, and the results are as follows:
EXAMPLE III Test Item Spore Survival" A Electronic components 0/6 Scapel (handle of blade) 0/6 Thermometers (0-150C) 0/6 Eating utensils (spoons, forks, and knives) 0/6 Optics (microscope lens) 0/1 Tissue culture plates Tissue culture flask O/ 1 Tissue culture dishes 0/1 Controls 3/3 "Number of positive sampes over number of samples exposed.
EXAMPLE I Percent Available Spore Survival After Indicated Exposure Formaldehyde 30 min. 1 hr. 2 hrs. 4 hrs. 6 hrs.
60C 90C 60C 90c 60C 90C 60C 90C 60C 90C 0.082 3/3 0/3 3/3 0/3 3/3 0/3 3/3 0/3 2/3 0/3 0.167 3/3 0/3 3/3 0/3 3/3 0/3 1/3 0/3 0/3 0/3 0.994 3/3 0/3 3/3 O/3 0/3 0/3 0/3 0/3 0/3 0/3 2.17 3/3 0/3 3/3 0/3 0/3 0/3 0/3 0!} O/3 O/3 Control 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 3/3 of sterilization. In addition, the compound used for releasing formaldehyde is more stable; i.e., the comound is not readil susce tible to curin or condensa- EXAMPLE II p. y p g tron, which facilitates production. These and other ad- Formaldehyde Content of Paper is 1.42%
Exposure Cycle Time Spore Survival After Indicated Cycle Temperatures min hrs. 125C 90C 60C 45C 37C Indicates complete test spore inactivation at indicated cycle time and temperature exposure.
I Indicates some samples showing complete inactivation of test spores.
+ Indicates no complete inactivation of test spores.
vantages should be apparent to those skilled in the art from the teachings herein.
Numerous modifications and variations of the present invention are possible in light of the above teachings and, therefore, within the scope of the appended claims, the invention may be practised otherwise than as particularly described.
What is claimed is:
l. A package, said package having paper therein treated with a sterilizing amount of hexamethoxymethylmelamine, said paper containing from 0.1 to 20%, by weight, formaldehyde, provided by the hexamethoxymethylmelamine, whereby upon heating a sterilizing amount of formaldehyde is released in the package to effect sterilization.
2. The package of claim 1 wherein the paper forms at least a portion of the interior surface of the package.
3. The package of claim 1 wherein the paper is separately placed in the package.
6 4. A package, said package in ludi an ti l t b 5. The package of claim 4 wherein the outer wall sursterilized, said package having paper therein treated face of the Package 18 F P with a sterilizing amount of hexamethoxymethylmela- The package of clam] 5 wherem the paper a wrapping around the article in said package.
sand paper comammg from to by 5 7. The package of claim 4wherein the outer wall surweight formalfiehyde provided by h face of the package has a low vapor transmission level. ymethylmelamme, whereby p heatmg a Stenhzmg 8. The package of claim 7 wherein the paper is :1 amount of formaldehyde is released in the package to wrapping round the article,