Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
1999-01-27
2001-11-06
Hess, Bruce H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C430S048000
Reexamination Certificate
active
06312789
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a recording sheet using toner such as a recording sheet for electrophotography and a process for thermally fixing a toner image formed thereon, and particularly relates to a recording sheet and a process for thermally fixing capable of preventing quality of a toner image from being degraded despite of no oil supplied to a fixing means. The present invention is preferably applicable to a OHP film having a good transparency and a thermally fixing process thereof.
2. Description of the Related Art
In a general electrophotography system, a toner image is formed on a recording sheet by transferring toner, and the toner image is then thermally fixed thereon by heating and pressing by means of a fixing means such as a fixing roller. The fixing roller is generally provided with a mechanism going on applying silicone oil thereto to reduce affinity of the toner to the fixing roller for the purpose of preventing offset of the toner itself.
When the recording sheet is used to form a colored image, and particularly adapted for an OHP(i.e., an over head projector) system, a receptor layer having a good affinity to the toner is generally formed on a plastic substrate film of the recording sheet in order to improve transparency of the toner image. Offset of the receptor layer itself owing to the thermal fixing is also prevented by application of the silicone oil.
A recording sheet for OHP has recently used as a preferable communicative medium on various occasions such as a lecture, a school, a company, an explanatory meeting, an exhibition or the like, and wish for a high quality of an image has grown stronger. Wish for an oil-less fixing system is then growing stronger because of unpleasantness of the silicone oil adhering to the recording sheet for OHP, degradation of the image owing to the silicone oil, an environmental issue or the like.
When a conventional recording sheet for OHP having a receptor layer essentially formed of a low molecular thermoplastic resin is used in the oil-less fixing system, the oil-less fixing system however causes sticking or fusion of the receptor layer of the recording sheet to the fixing roller or cohesive failure of the receptor layer itself, thus involving the recording sheet in deterioration of transparency.
There has been made many proposals for the toner, the recording sheet and the fixing process in order to realize the oil-less fixing process.
Japanese Patent Application Laid-open (KOKAI) Hei 9(1997)-218527 proposes that a receptor layer on a substrate contains a thermoplastic resin and a release agent having a melting point in a range of 40-120° C. It is however difficult for such a proposed recording sheet to prevent cohesive failure of the receptor layer because the thermoplastic resin in the receptor layer is easily softened in order to improve quality of the image.
Japanese Patent Application Laid-open (KOKAI) Hei 9(1997)-171265 proposes that a flow beginning temperature of a binder resin in a receptor layer is set to 0-10° C. higher than that of a binder resin in toner, and an angle made by an inclination of a protruding portion of a toner particle lodges in the receptor layer is set to 40 degrees or less with respect to the receptor layer. Though this prior art discloses that a surface temperature of a fixing roller should be set within a range of 130-160° C., the receptor layer is actually liable to be caused offset in this range of the surface temperature.
Japanese Patent Application Laid-open (KOKAI) Hei 9(1997)-160278 proposes a receptor layer containing a thermoplastic resin and a release agent selected among silicone oil and fluorine type oil. It is however difficult for such a proposed receptor layer to provide a high quality of an image because toner embedded in the receptor layer is not compatible with the release agent.
Japanese Patent Application Laid-open (KOKAI) Hei 9(1997)-152736 proposes a receptor layer containing a thermoplastic resin and a plasticizer. Such a proposed receptor layer is however involved in the same problem of compatibility.
SUMMARY OF THE INVENTION
A first object of the present invention is to provide a recording sheet using toner such as a recording sheet for electrophotography, which is applicable to an oil-less fixing system so as to eliminate problems caused by adhering of a silicone oil such as sticking, glaring reflection and deterioration of image quality, and can also prevent sticking or fusion to a fixing means such as a fixing roller and occurrence of cohesive failure of the receptor layer itself to secure a good transparency of the recording sheet and a high quality of a toner image even when no oil is supplied to the fixing means in the fixing process.
A second object of the present invention is to provide a process for thermal fixing using such a recording sheet with no oil supplied to the fixing means.
A recording sheet according to the present invention comprises a substrate film, a receptor layer for retaining a toner image and a release layer for releasing the receptor layer from a fixing surface of a fixing means, the receptor layer and the release layer being disposed on at least one side of the substrate film in this order from a position of the substrate film, wherein the release layer contains a release agent having compatibility to toner and releasing ability to the fixing surface.
In the present invention, a process for thermally fixing a toner image formed on a recording sheet comprises the steps of;
providing the recording sheet comprising a substrate film, a receptor layer for retaining a toner image and a release layer for releasing the receptor layer from a fixing surface of a fixing means, the receptor layer and the release layer being disposed on at least one side of the substrate film in this order from a position of the substrate film, wherein the release layer contains a release agent having compatibility with toner and releasing ability to the fixing surface,
forming the toner image on an area provided with the receptor layer of the recording sheet,
putting a heated fixing surface of a fixing means into press contact with an area having the toner image, and,
removing the fixing surface of the fixing means from the area having the toner image.
The recording sheet of the present invention has a layered structure composed of the substrate film, the receptor layer formed on at least one surface side of the substrate film, the release layer formed on outside of the receptor layer and optional layers formed at any positions as required, in which the receptor layer essentially or mainly undertakes a function to receive and fix the toner, while the release layer essentially or mainly undertakes a function to release the recording sheet from the fixing surface of the fixing means with no occurrence of fusion between them though the fixing surface thermally presses the toner image.
According to the present invention, the recording sheet can provide a high quality of the toner image with no occurrence of fusion to the fixing surface and cohesive failure of the receptor layer even when the thermal fixing is carried out with no oil supplied to the fixing surface of the fixing means.
A preferable release agent is wax, particularly wax having a polar group in its molecular structure, such as carnauba wax, candelilla wax or mixture thereof. The wax is excellent in compatibility to the toner and releasing ability to the fixing surface.
It is preferable that the wax has a melting point in a range of 50 to 130° C. With a melting point of the wax in the above range, the wax can be melted at a typical fixing temperature, thus making a smooth releasing.
An amount of the wax is preferably 30% by weight or more, and more preferably 50% by weight or more to a weight of the release layer.
It is preferable to form the release layer from material substantially containing only wax or only wax as the release agent and thermoplastic resin as a binder. Any additive may be incorporated in the release layer nevertheless. As
Egashira Noritaka
Hayashi Masafumi
Dai Nippon Printing Co. Ltd.
Grendzynski Michael E.
Hess Bruce H.
Ladas & Parry
LandOfFree
Recording sheet and process for thermally fixing toner image... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Recording sheet and process for thermally fixing toner image..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Recording sheet and process for thermally fixing toner image... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2614062