Synthetic resins or natural rubbers -- part of the class 520 ser – Synthetic resins – Processes of preparing a desired or intentional composition...
Reexamination Certificate
1999-03-11
2003-08-26
Mulcahy, Peter D. (Department: 1713)
Synthetic resins or natural rubbers -- part of the class 520 ser
Synthetic resins
Processes of preparing a desired or intentional composition...
C428S398000, C428S364000, C428S421000
Reexamination Certificate
active
06610766
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to polyvinylidene fluoride resin compositions, and more particularly to polyvinylidene fluoride resin compositions which can be suitably used in the fields of which semiconductivity and/or transparency are required.
The resin compositions according to the present invention are suitable for use, for example, as resin materials for forming at least surface layers of charge controlling members (semiconductive members) such as charging rolls, transfer rolls, image-forming rolls, charging belts and destaticizing belts in image forming apparatus of the electrophotographic system making good use of their semiconductivity. The resin compositions according to the present invention are also suitable for use in application fields making good use of their static electricity controlling property, antistatic property, anti-dust-collecting property and the like, for example, as charge controlling members such as packaging materials (for example, films, bags and containers) for electronic parts, wall paper, sheathing materials for OA apparatus and anti-static partitions. In the present invention, the term, “semiconductive resin composition” means a resin material the volume resistivity of which lies between an insulator and a metallic conductor, and more specifically means a resin material having a volume resistivity of about 10
5
-10
13
&OHgr;cm.
The resin compositions according to the present invention are suitably used, as application fields making good use of transparency (high light transmittance and low haze), as optical resin materials for optical members such as optical fibers and lenses, light-transmitting materials for solar cells, and lightening covers. The resin compositions according to the present invention are suitably used as optical members such as anti-dust-collecting window glass and protective materials for displays making good use of both properties of semiconductivity and transparency.
BACKGROUND OF THE INVENTION
In the fields of electric and electronic apparatus, resin materials the volume resistivities of which have been precisely controlled are demanded as semiconductive materials. For example, in image forming apparatus (electrophotographic copying machine, electrostatic recording apparatus, etc.) of the electrophotographic system, such as copying machines, facsimiles and laser-beam printers, images are formed through steps such as charging, exposure, development, transfer, fixing and static charge eliminating. In order to form respective members used in these steps, resin materials the volume resistivities of which have been precisely controlled are required.
A charging roll or belt, a transfer roll or belt, a developing roll, a blade for controlling the thickness of a toner layer, and the like installed in such an image forming apparatus are required to be semiconductive at least at their surface layers, and specifically to have a desired volume resistivity within a range of about 10
5
-10
13
&OHgr;cm. For example, in a charging system making use of the charging roll or belt, voltage is applied to the charging roll or belt, and the charging roll or belt is then brought into contact with a photosensitive drum, whereby an electric charge is directly applied to the photosensitive drum to equally and uniformly charge the photosensitive drum. In a development system making use of the developing roll, a toner is adsorbed in a charged state on the surface of the developing roll by frictional force between the developing roll and a toner supply roll, and this toner is uniformly leveled by the blade for controlling the layer thickness of the toner, and the toner is then caused to fly toward an electrostatic latent image formed on the photosensitive drum by electric attraction force to develop the latent image. In a transferring system making use of the transfer roll or belt, voltage having a polarity opposite to that of the toner is applied to the transfer roll or belt to generate an electric field, whereby the toner on the photosensitive drum is transferred to a transfer material by electric attraction force generated by the electric field.
Accordingly, the charge controlling members such as the charging roll or belt in the image forming apparatus are required to have a low volume resistivity within a proper range. The volume resistivity itself is required to be uniform in distribution. If the volume resistivity varies with location, no high-quality image can be provided. For example, if the volume resistivity distribution of the charging roll or belt is uneven, it is difficult to equally and uniformly charge the photosensitive drum, so that the quality of the resulting image is deteriorated. In these members, it is also required that their volume resistivities and surface resistivities are not very changed by change of humidity. If the volume resistivities and surface resistivities of the charge controlling members are greatly changed by change of humidity in an ordinary use environment, no high-quality image can be stably provided.
Further, when dust, toner and/or the like are adsorbed on sheathing materials and parts of OA apparatus formed from a resin material, their appearances are impaired, or the cause of trouble is formed. When resin-made apparatus and parts used in the fabrication processes of semiconductor devices, LCD and the like, and films, bags and containers for packaging electronic parts such as IC and LSI adsorb dust by generation of static electricity, the quality of the electronic parts is impaired. It is therefore required that a volume resistivity of about 10
5
10
13
&OHgr;cm is imparted to resin materials used in these application fields, particularly, in face-layer materials thereof so that they may have good charge controlling.
As methods for lowering the electrical resistance (volume resistivity) of polyvinylidene fluoride resins and molded or formed products (hereinafter may be referred to as “moldings”) thereof, there have heretofore been known (1) a method in which an organic antistatic agent is applied to the surfaces.of the resin moldings, (2) a method in which an organic antistatic agent is incorporated into the resins, (3) a method in which a conductive filler such as carbon black or metallic powder is incorporated into the resins, and (4) a method in which an ionic electrolyte is incorporated into the resins.
However, the method (1) involves a problem that since the polyvinylidene fluoride resins have excellent anti-adhesion property, the antistatic agent easily falls off from the surfaces of the moldings by wiping or washing the surfaces. In the method (2), a surfactant or hydrophilic resin is used as the organic antistatic agent. Since the method making use of the surfactant adopts a mechanism that the surfactant is caused to bleed out of the surface of each molding, thereby imparting antistatic property thereto, its volume resistivity and antistatic property are greatly changed by changes of environments such as temperature and humidity. In addition, high stain resistance, which is a merit of the polyvinylidene fluoride resins, is impaired. In the method making use of the hydrophilic resin, it is necessary to incorporate a great amount of the hydrophilic resin in order to achieve a desired antistatic effect. Therefore, excellent physical properties inherent in the polyvinylidene fluoride resins, such as stain resistance, weather resistance, ozone resistance and solvent resistance, are lowered. In addition, the method involves a problem that the dependency of volume resistivity and antistatic property on humidity becomes high. The stain resistance and solvent resistance are properties required in the case where a toner applied to a member arranged in an image forming apparatus of the electrophotographic system is removed by cleaning. Since an image forming apparatus equipped with a corona discharge device or the like generates ozone, the ozone resistance is also a property required of members in such an apparatus. The weather resistance is a property required in the case where the r
Kitamura Hideki
Matsunaga Satoru
Teramoto Yoshikichi
Kureha Kagaku Kogyo K.K.
McDermott & Will & Emery
Mulcahy Peter D.
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