Radiation imagery chemistry: process – composition – or product th – Electric or magnetic imagery – e.g. – xerography,... – Post imaging process – finishing – or perfecting composition...
Patent
1997-03-06
2000-10-24
Buttner, David J.
Radiation imagery chemistry: process, composition, or product th
Electric or magnetic imagery, e.g., xerography,...
Post imaging process, finishing, or perfecting composition...
430 47, 428220, 525470, 399297, C08L 6900, C08G 6410, G03G 700
Patent
active
061364940
DESCRIPTION:
BRIEF SUMMARY
FIELD OF THE INVENTION
The present invention relates to a transfer sheet, and more particularly, to a transfer sheet for a printing medium for use in electrophotographic copying machines, printers or the like.
BACKGROUND ART
In general, transfer sheets are composed of a synthetic resin sheet and have a transferring function for causing images formed on a photosensitive drum to be transferred thereonto. In some cases, the transfer sheets also have a transporting function for causing the images carried on the photosensitive drum to be transported to copying papers and a separating function for causing the copying papers on which the images have already been transferred, to be separated therefrom. The transfer sheets are generally used in the form of a drum or a belt, and always under go a mechanical load during the use. For this reason, it is required that the transfer sheets exhibit a high strength against repeated loading, i.e., a high fatigue strength in addition to a so-called mechanical strength and elongation.
It has been strictly required that the afore-mentioned mechanical durability of the transfer sheets is so high as to withstand several ten thousands of copying operations. The mechanical durability of the transfer sheets varies depending upon structure or configuration of the copying machines or printers in which the transfer sheets are used, and therefore is evaluated by the below-mentioned testing methods. The transfer sheets are required, if possible, to exhibit a mechanical durability capable of withstanding not less than a hundred thousand copying operations when evaluated by such testing methods. However, it has been considered by a person skilled in the art that the afore-mentioned high mechanical durability of the transfer sheets is extremely difficult to realize by using an existing moldable synthetic resin sheet.
Further, since the transfer sheets are used as an electrical part to which a high voltage is applied, it is inevitably required that they have flame-retardant properties. The flame-retardant properties required for the transfer sheets are as high as not less than VTM-2 according to Underwriters Laboratories (UL) Standard No. 94 (Underwriters Laboratories Inc.). However, the increase in flame-retardant properties of a resin material causes the deterioration in its mechanical strength, while the increase in the mechanical strength causes the deterioration in the moldability and the flame-retardant properties. Therefore, it is extremely difficult to satisfy these properties simultaneously.
The present invention has been accomplished in view of the afore-mentioned problems. It is an object of the present invention to provide a transfer sheet which satisfies a high mechanical durability, high flame-retardant properties and a high moldability, simultaneously.
DISCLOSURE OF THE INVENTION
That is, an aspect of the present invention lies in a transfer sheet comprising not less than 75% by mass of a polycarbonate-based resin, and has a ratio of an infrared absorbency at a wave-number of 155 mm.sup.-1 to that at 160 mm.sup.-1 of not less than 0.02 and less than 0.3, a melting viscosity of not less than 2,500 Pa.multidot.s when measured at 280.degree. C. by a Koka-type flow tester and a thickness of 130 to 250 .mu.m.
The present invention is described in detail below. Incidentally, in the following description, the polycarbonate resin is referred to merely as "PC resin".
The transfer sheet according to the present invention may be produced by using a PC resin or a PC resin-containing composition as a raw material and generally extruding the material into an appropriate shape. The content of the PC resin in the PC resin-containing composition may be not less than 75% by mass. Other resin components than the PC resin in the PC resin-containing composition cab be optionally selected unless the addition thereof adversely influences the effects of the present invention. For example, as other resin components in order to reduce an electrical resistance of the resultant composition, graft
REFERENCES:
patent: 3334154 (1967-08-01), Kim
patent: 4140730 (1979-02-01), Binsack
patent: 4352847 (1982-10-01), Okiyama
patent: 5601913 (1997-02-01), Ohtani
patent: 5612163 (1997-03-01), Teramoto
Matsunaga Satoru
Misawa Tooru
Teramoto Yoshikichi
Buttner David J.
Conlin David G.
Kureha Kagaku Kogyo Kabushiki Kaisha
Lowen Cara Z.
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