Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using direct contact with electrical or electromagnetic...
Reexamination Certificate
1999-05-27
2001-02-06
Beisner, William H. (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using direct contact with electrical or electromagnetic...
C422S028000, C422S298000, C422S302000
Reexamination Certificate
active
06183691
ABSTRACT:
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to sterilization of packaging. Specifically, the present invention relates to an apparatus and method for the sterilization of packaging using UYV radiation and vapor-phase hydrogen peroxide.
2. Description of the Related Art
The present invention relates to an ultra-violet lamp assembly for use in irradiating packaging material in a form-fill-seal packaging machine. More particularly, the present invention relates to an ultra-violet lamp assembly for use in irradiating packaging material in a packaging machine wherein the ultra-violet lamp and its associated components are readily subject to cleaning or service.
Milk or juice is often packaged in cartons that have been sterilized to prolong shelf life of the contents under refrigeration. When milk or juice is being packaged under aseptic packaging conditions, the content are capable of being stored for a substantial period of time at room temperature without spoilage. Both of these packaging processes require effective sterilization of the packaging material prior to filling of a container formed from the packaging material. For example, a container, such as a gable-top container, that has previously been formed may have its interior surfaces sterilized prior to being filled with product. U.S. Pat. No. 4,375,145, discloses a packaging machine having a conveyor on which pre-formed cartons advance under ultraviolet germicidal solution, such as hydrogen peroxide, passing under the ultraviolet lamps.
U.S. Pat. No. 4,289,728, discloses a method for sterilization of the surfaces of food containers and other materials by applying a hydrogen peroxide solution, followed by ultraviolet radiation. This patent indicates that the peak intensity of ultraviolet radiation occurs at a wavelength of 254 nm. The concentration of the hydrogen peroxide solution is less than 10% by weight, and furthermore, the hydrogen peroxide solution is heated during or subsequent to irradiation. UV sterilization has been shown to be suitable for sterilization of flat films but has been found to have limited applicability to preformed, angular containers (Maunder, 1977) due to the geometric and physical constraints associated with UV light. If a simple UV lamp is placed in close proximity above a preformed, such as a gable top carton, the sterilization effectiveness is severely limited due to several reasons. The total light flux entering the carton is restricted to light that can be directed through the carton opening, which in case of typical gable top cartons are 55×55 mm, 70×70 mm or 95×95 mm. Unreflected light emitted from a line source UV lamp decreases in intensity with the square distance from the light source. Thus, as the depth of the carton increases, the light intensity falls off.
Another problem in sterilizing these cartons with UV light is that the light enters the top of the carton and radiates toward the bottom substantially parallel to the sides of the carton. The germicidal effect of the light that impinges on the side is very low because of the high angle incidence. Thus, the sides of the cartons are the most difficult surfaces to sterilize, especially for tall cartons. When the cartons are positioned on the conveyor, two sides of the carton lie in a plane that is parallel to the axis of the lamp, while the other two sides are transverse to the axis of the lamp. Since the lamp is elongated, radiation impinges on the transverse sides of the carton at a higher angle of incidence than it does on parallel sides of the carton. In the case of a single UV lamp source above the center of a 70×70×250 mm rectangular carton, the effective light intensity at the bottom of the carton would be reduced to 13.9% of the maximum intensity at that distance from the source. The carton sides transverse to the lamp axis receive light from the entire length of the bulb. Light originating from the lamp reflector on the side opposite the parallel carton wall will have a minimum incident angle and thus have an intensity equal to 27.0% of the lamp intensity.
One ultraviolet lamp assembly that is designed to address, among other things, the problem of effective irradiation of pre-formed packages is disclosed in U.S. Pat. No. 5,433,920, to Sizer et al. In accordance with one aspect of the invention disclosed therein, an ultraviolet reflector for use with an ultraviolet lamp is utilized to effectively irradiate the sides as well as the bottom of the container.
A problem with current sterilization practices is the limitation of concentration of hydrogen peroxide which may be used on packaging material for food. Only a minute quantity of hydrogen peroxide residue may be found on the packaging which limits most applications to less than 1% concentration.
BRIEF SUMMARY OF THE INVENTION
On aspect of the present invention is a method for sterilization of packaging at a sterilization station on a form, fill and seal machine. The first step of the method is providing packaging to be sterilized at the sterilization station. The next step is subjecting the packaging to a predetermined quantity of vapor-phase hydrogen peroxide thereby creating a packaging coated with a thin layer of hydrogen peroxide. The next step is irradiating the coated packaging with ultraviolet radiation for a predetermined set of time thereby creating an irradiated packaging. The next step, and possibly final step is drying the irradiated packaging with heated air for a predetermined amount of time thereby creating a sterilized packaging having less than 0.5 parts per million residue of hydrogen peroxide.
Another aspect of the present invention is an apparatus for sterilizing packaging at a sterilization station on a form, fill and seal machine. The apparatus includes moving means, a sprayer, an ultraviolet radiation source and a heated air distributor. The moving means moves the packaging to the sterilization station. The sprayer subjects the packaging to a predetermined quantity of vapor-phase hydrogen peroxide thereby coating the packaging with a thin layer of hydrogen peroxide. The ultraviolet radiation source irradiates the coated packaging with ultraviolet radiation for a predetermined set of time and is downline from the sprayer. The heated air distributor flows hot air onto the packaging.
It is a primary object of the present invention to provide a method and apparatus for providing an extended shelf life packaging.
It is an additional object of the present invention to provide a method and apparatus for sterilizing packaging material on a form, fill and seal packaging machine using gaseous hydrogen peroxide and UV radiation.
It is yet an additional object of the present invention to provide a method and apparatus for sterilizing packaging material using hydrogen peroxide having a concentration upwards to 53%.
Having briefly described this invention, the above and further objects, features and advantages thereof will be recognized by those skilled in the pertinent art from the following detailed description of the invention when taken in conjunction with the accompanying drawings.
REFERENCES:
patent: 4289728 (1981-09-01), Peel et al.
patent: 4366125 (1982-12-01), Kodera et al.
patent: 4992247 (1991-02-01), Foti
patent: 5129212 (1992-07-01), Duffey et al.
patent: 5547635 (1996-08-01), Duthie, Jr.
Palaniappan Sevugan
Swank Ronald
Beisner William H.
Tetra Laval Holdings & Finance SA
Welsh & Katz, LTD
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