Plastic and nonmetallic article shaping or treating: processes – Direct application of electrical or wave energy to heat the... – Electrical heating
Patent
1998-08-03
1999-10-12
Kuhns, Allan R.
Plastic and nonmetallic article shaping or treating: processes
Direct application of electrical or wave energy to heat the...
Electrical heating
264 464, 264 51, 264134, 264402, 264416, B29C 4402, B29C 4406
Patent
active
059650800
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method of manufacturing starch-based biodegradable molded objects made of biodegradable materials including starch.
BACKGROUND ART
Examples of starch-based biodegradable molded objects include trays, cups, corner pads, etc. One method of manufacturing this kind of starch-based biodegradable molded object is the external heating method, in which the materials are placed into a mold previously heated to a predetermined temperature, and molding is performed using heat conductivity.
However, with methods of this kind, slow molding leads to low productivity, and unevenness in the temperature of the mold causes uneven baking, thus making it impossible to obtain a uniform consistency.
For this reason, in another method, alternating current is supplied to a metal mold, and internal heating is induced in the materials in the mold by electromagnetic wave heating, such as resistance heating or dielectric heating, thereby baking and molding the materials. In this case, the metal mold is divided into two mold halves, which are insulated from each other by an insulating material provided therebetween, and an alternating current electrode is connected to each mold half. Then alternating current is applied to the metal mold through these electrodes, and the materials in the mold are baked and molded by resistance heating or dielectric heating.
However, with the foregoing method using resistance heating or dielectric heating, during molding, liquid contained in the materials evaporates, producing a large amount of vapor, which condenses, causing insulation breakdown, and thus resistance heating or dielectric heating does not go well.
DISCLOSURE OF THE INVENTION
The object of the present invention is to provide a method of manufacturing starch-based biodegradable molded objects capable of preventing insulation breakdown due to condensation of a large amount of vapor evaporating from the materials during heating and molding of the molded objects by resistance heating or dielectric heating.
In order to attain the foregoing object, a first method of manufacturing starch-based biodegradable molded objects according to the present invention is a method of manufacturing molded objects by placing biodegradable materials containing starch in a mold made up of first and second conductive mold halves and an insulating section therebetween, and applying across both mold halves alternating current from an alternating current power source, thus heating and expanding the materials by means of resistance heating and/or dielectric heating, in which the insulating section of the mold is provided with a vapor release section, pressure is reduced outside the mold, and the heating is performed while releasing vapor produced thereby through the vapor release section.
A second method of manufacturing starch-based biodegradable molded objects is a method of manufacturing molded objects by placing biodegradable materials containing starch in a mold made up of first and second conductive mold halves and an insulating section therebetween, and applying across both mold halves alternating current from an alternating current power source, thus heating and expanding the materials by means of resistance heating and/or dielectric heating, in which the insulating section of the mold is provided with a vapor release section, the vapor release section is heated, and the heating of the materials is performed while releasing vapor produced thereby through the vapor release section.
With these methods, condensation of vapor can be prevented, and thus insulation breakdown can be prevented.
Additional objects, features, and strengths of the present invention will be made clear by the description below. Further, the advantages of the present invention will be evident from the following explanation in reference to the drawings.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is an explanatory drawing showing one structural example of a heating device for a method of manufacturing starch-based biodegradable mold
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Ando Sadamasa
Haruta Toshitaka
Karasawa Taizo
Kurisaka Takayuki
Oowada Tsutomu
Kuhns Allan R.
Nissei Kabushiki Kaisha
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