Patent Number: 048291897
Section: summary

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for low-temperature plasma treatment of a sheet material such as a cloth and a film for improving the quality of the product obtained, particularly by controlling the temperature of the material in the course of treatment and including a feeding device of electric energy to the apparatus. 2. Description of the Related Art It has been developed recently to subject a sheet material such as a long cloth and a long film produced commercially to low-temperature plasma treatment by transporting said sheet material through a reaction chamber in which low-temperature plasma is generated for improving the quality of the material treated. The mechanism of the conventional apparatus for low-temperature plasma treatment of a sheet material is to supply a gas for generating plasma into a reaction chamber provided with an electrode for generating plasma and to feed high frequency with a frequency of, for instance, 13.56 MHz to the electrode for generating low-temperature plasma in the reaction chamber. By transporting a sheet material through gas atmosphere thus excited with low-temperature plasma, the plasma treatment in object can be accomplished. However, in such a conventional apparatus for low-temperature plasma treatment of a sheet material, there have been shortcomings in such points as the efficiency of generating low-temperature plasma, the quality low-temperature plasma gas generated and its utilizing efficiency. Namely, while it is possible to generate low-temperature plasma in the reaction chamber, low-temperature plasma gas utilized practically for the treatment of a sheet material passing through the reaction chamber is only a part of the gas generated and the remainder of the gas is usually abandoned in vain, thus deteriorating the utilization efficiency of the plasma or, in other words, the utilization efficiency of electric power for generating high frequency. Further, in a conventional apparatus for low-temperature plasma treatment in which a long sheet material is transported continuously therethrough a large amount of external atmosphere (air) is penetrated into the reaction chamber unavoidably due to the incompleteness of the seal mechanism thereof and the amount of by-product gas contaminated therein is increased unavoidably. As a result, there is a drawback that a large amount of by-product gas is absorbed on the surface of the sheet material, thus lowering the efficiency of treatment. Moreover, when there occurs a temperature change in the course of continuous low-temperature plasma treatment of a sheet material, particularly in the case of a textile product such as a cloth, the quality of the textile product after treatment is deteriorated due to the fluctuation of the treating temperature thereof, and in some instances when the temperature of the textile product is apart from the desirable treating temperature, the treatment in object cannot be done satisfactorily. Therefore, it is desirable in such a case that the temperature of a textile product passing through the low-temperature plasma gas atmosphere in a reaction chamber is constant at a suitable prescribed temperature through the period of treatment. In such a reaction chamber, however, such parts as guide rolls, electrode plates and walls in a reaction chamber are heated naturally in the progress of the treatment, and the heat thus accumulated is transmitted directly and/or indirectly to the textile product unavoidably. As a result, the temperature of the textile product is also elevated, and accordingly, the low-temperature plasma treatment thereof becomes non-uniform, causing the difficulty that the treatment in object cannot be attained satisfactorily. Separately, in subjecting a broad sheet material (for instance with a width of 90 to 180 cm) to low-temperature plasma treatment, a large size reaction chamber with a large size electrode is necessitated, and the leakage of plasma is easily caused to occur unavoidably due to the discharge between the feed wire and the electrode, causing a shortcoming that a large amount of energy must be consumed. For the purpose to depress such an energy loss, it is effective to transmit electric current by connecting a high frequency generating device outside of the reaction chamber and an electrode for generating low-temperature plasma in the reaction chamber with the use of a shielded wire (i.e., coaxial cable). However, since the insulating layer around the lead wire of a shielded wire comprises usually a resin with low heat-resistivity such as polyethylene, the heat accumulated in said electrode (to about 100.degree. C.) during treatment is transmitted to said shielded wire for heating it, and consequently, there occurs a difficulty that the insulation of said shielded wire is frequently broken due to the fusion of the insulating layer thereof which is consisted of a low heat resistive material such as polyethylene. SUMMARY OF THE INVENTION In view of such circumstances, the primary object of the present invention is to offer an apparatus for low-temperature plasma treatment of a sheet material in which the contamination of by-product gas in low-temperature plasma gas generated in the reaction chamber is prevented and the thus generated high quality low-temperature plasma gas is supplied directly to a sheet material for elevating the efficiency of plasma treatment and the quality of the product. The second object of the invention is, in such an apparatus, to reduce the amount of low-temperature plasma gas generated outside of the zone of transporting a sheet material as well as said gas abandoned to the exterior of the apparatus for increasing the utilization efficiency of low-temperature plasma gas and further for sparing the consumption of electric energy. The third object is to offer an apparatus in which the temperature of guide rolls for transporting a sheet material as well as the electrode for generating low-temperature plasma in the reaction chamber is controlled to a prescribed value for maintaining the temperature of the sheet material running through the reaction chamber to a desirable temperature so as to produce a product with a uniform and excellent quality. Finally, the fourth object is to offer an excellent feeding device of electric energy to the inventive apparatus for low-temperature plasma treatment of a sheet material. An apparatus for low-temperature plasma treatment of a sheet material chiefly to answer the primary and the second objects in the present invention comprises, to say in short, providing a plurality of reaction zones through which a sheet material to be treated is transported in an enclosed reaction chamber whose inner pressure can be reduced, in which said reaction zones being provided respectively with an electrode communicative to a high frequency generating device outside of the reaction chamber and a plurality of jet nozzles for supplying a gas for generating low-temperature plasma, and said reaction chamber and said reaction zones being earthed. Details of the apparatus of this type will be illustrated in Example 1 as will be described hereinafter. Another apparatus for low-temperature plasma treatment of a sheet material, which is particularly fitted for the purpose to answer the third object of the invention and will be illustrated in detail in Example 2 in the following, may be summarized as follows: A plurality of guide rolls for transporting a sheet material therethrough, a plurality of electrode plate pairs in which a passage of the sheet material thus transported is provided respectively therebetween, a liquid medium passage passing through said guide rolls and in adjacent to said electrode plate pairs for heating or cooling them, and a means for controlling the temperature of said guide rolls and said electrode plate pairs to a prescribed temperature by passing a liquid medium through said passage are provided in an enclosed reaction chamber in which low-temperature plasma can be generated under reduced pressure. An electric energy feeding device for one of the apparatuses for low-temperature plasma treatment of a sheet material mentioned in the above and to meet with the fourth object of the invention comprises connecting a shielded wire coming out of a high frequency generating device to an electrode for generating low-temperature plasma provided in a reaction chamber electrically by putting a shielded wire jointer provided with a cooling mechanism therebetween. Details of this device will be illustrated in Example 3 in the following. In applying the present inventive apparatus, low-temperature plasma treatment of a sheet material such as a textile product and a film can eminently and effectively be done.