Chemical apparatus and process disinfecting – deodorizing – preser – Process disinfecting – preserving – deodorizing – or sterilizing – Using direct contact steam to disinfect or sterilize
Reexamination Certificate
2000-08-08
2003-04-08
Thornton, Krisanne (Department: 1744)
Chemical apparatus and process disinfecting, deodorizing, preser
Process disinfecting, preserving, deodorizing, or sterilizing
Using direct contact steam to disinfect or sterilize
C422S001000, C422S292000, C422S302000, C422S303000, C422S297000, C422S300000
Reexamination Certificate
active
06544473
ABSTRACT:
This application is based upon and claims the benefit of priority from the prior Japanese Patent Applications No. 10-037613, filed Feb. 19, 1998; and No. 10-037614, filed Feb. 19, 1998, the entire contents of which are incorporated herein by reference.
BACKGROUND OF THE INVENTION
The present invention relates to a method for performing sterilizing treatment on such a plastic container as a PET bottle and the like. In particular, the present invention relates to a method and an apparatus for performing heating and sterilizing treatment on an inner face of a plastic container having a low heat-resistance securely without thermally deforming the same.
Conventionally, the so-called PET bottle is widely used as a plastic container filled with a drink or the like. In this case, before a drink is filled in such a PET bottle, sterilizing treatment must be performed on an inner face of the bottle. Incidentally, as the sterilizing treatment for a drink container, there are various treatments such as sterilization which dies out bacteria completely in a strict sense, sterilization which reduces or incapacitates bacteria down to a required level, and the like. In this specification, treatments including all of these treatments are referred to as sterilizing treatments.
As such a sterilizing treatment, there is one where heating and sterilizing treatment is performed by jetting hot water on to an inner face of a PET bottle. Such a heating and sterilizing treatment is generally applied alone or in combination with another sterilizing treatment such as jetting of ozone water or the like. In such a heating and sterilizing treatment, there are advantages such as simple steps, secure treatment and the like, but there are the following problems to be solved.
The first problem is that heat resistance is required for a container to be subjected to sterilizing treatment. In order to obtain effect of sterilizing treatment, it is necessary to jet hot water having a temperature of 65 to 70° C. or more. However, such a high temperature exceeds a heat resistance temperature of resin material for a container and deformation occurs in the container due to heat. Accordingly, for example, in a case that heating and sterilizing treatment is performed by jetting hot water on an inner face of a PET bottle, it is necessary to use a PET bottle using heat resistance material. For this reason, cost for a container is increased and kind of containers which can be subjected to sterilizing treatment is limited.
Also, the second problem is related to a temperature range of hot water and safety. When the temperature of this jetting hot water becomes higher, the effect of the sterilizing treatment becomes higher, so that it is preferable that the temperature of the hot water is higher. However, since there are portions where pressure of hot water is lowered locally inside pipes or valve apparatuses for supplying the hot water, when the temperature of the hot water becomes about 90° C. or more, there is a possibility that boiling occurs at low pressure generating portions in the pipes or the valve apparatuses, so that the temperature of the hot water must be maintained at about 90° C. or less. Also, though it is considered that the hot water is pressurized and supplied thereby preventing boiling in pipes such as the above, hot water having a high pressure and a high temperature is not preferable in view of safety because there is a high risk that, if the pipe or the like is broken, hot water is scattered far and it attaches to a human body to burn him/her.
Also, the third problem is related to energy cost for producing the above hot water. In this manner, since the hot water which has been jetted on the inner face of the container is disposed as it is, energy cost for producing a large amount of hot water becomes high.
Furthermore, the fourth problem is a problem where hot water is jetted uniformly on the inner surface of the container. When a container to be subjected to sterilizing treatment has a complicated shape, it becomes difficult to jet hot water uniformly and thoroughly on the inner surface thereof. Also, even when the entire shape of a container is simple, for example, in the case of a PET bottle, there are many bottles where a number of ribs or recess/projection portions are formed on wall faces in order to increase rigidity of a bottle, improve design matter, and the like. There is a possibility that portions where jetting of hot water or falling-down thereof is obstructed are formed on these ribs or recess/projection portions, so that reliability of sterilizing treatment may be injured in some cases. Also, recently, a PET bottle which is crushed to decrease its volume at a time of disposal has been required. In such a bottle, it is anticipated that wall faces of the bottle are constituted in a complicated manner in order to facilitate crushing. In such a case, there is a possibility that portions of the bottle on which hot water is not jetted sufficiently occur.
In order to solve the above first problem, there has been recently proposed a method where hot water is jetted on an inner face of a PET bottle and simultaneously cooling water is jetted on an outer face of the bottle to cool the bottle wall face so that the bottle is prevented from deforming due to heat. According to such a method, since the temperature of the bottle wall face is prevented from increasing, such an effect can be obtained that it is made possible to perform heating and sterilizing treatment of hot water jetting even on an anti-heat resistant bottle.
However, it is necessary to suppress the temperature of the jetting hot water to 90° C. or less in order to prevent boiling or the like in pipes in the above manner, and there is a limitation in the temperature of the hot water. Also, the heat transfer from the hot water to the bottle wall face is a heat transfer due to impingement of jet flow of fluid to wall face, so-called impinge heat transfer, and it is a heat transfer system having a highest efficiency as a heat transfer system between fluid and wall face. Accordingly, since a large amount of heat is transferred from hot water to bottle wall face, the effect of the prevention of temperature rising on the wall face becomes insufficient even if the outer face of the bottle is being cooled. For this reason, for example, in a case of an anti-heat resistant PET bottle, the temperature of the hot water must be set to a temperature lower that the above 90° C. in order to prevent thermal deformation of the bottle. Accordingly, the efficiency or reliability of the heating and sterilizing treatment is lowered.
Also, in the above method, there is an effect that deformation of a container due to heat can be prevented in the above manner, but the above-mentioned second and fourth problems can not be solved essentially.
In order to solve the problems as mentioned above, a method is considered that an outer face of a bottle is cooled with cooling water or the like and steam is jetted on to an inner face of the bottle so that heating and sterilizing treatment is performed. Steam has a heat capacity smaller than that of hot water, so that only an inner face portion of a wall face of a bottle is heated to a high temperature but the heat amount transferred to the wall face is small. For this reason, the temperature of an outside of the wall face of the bottle is suppressed to a low temperature so that heat deformation of the bottle can be prevented effectively. Also, since there occurs no boiling in pipes or the like, the temperature of steam can be made higher than that of hot water and heating and sterilizing treatment can be performed more effectively. Also, since steam has a high fluid property and it is not affected by gravity, even when the shape of a bottle is complicated, steam contacts with an inner face of the bottle uniformly so that it is made possible to perform heating and sterilizing treatment securely.
By the way, the steam which has been jetted inside a bottle is circulated inside the bottle and exhausted from a mouth portion. Since
Amano Eizou
Shintaku Kenichi
Nixon & Vanderhye PC
Shintaku Kogyo Co., Ltd
Thornton Krisanne
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