Stock material or miscellaneous articles – Structurally defined web or sheet – Discontinuous or differential coating – impregnation or bond
Reexamination Certificate
2000-03-24
2002-09-24
Kelly, Cynthia H. (Department: 1774)
Stock material or miscellaneous articles
Structurally defined web or sheet
Discontinuous or differential coating, impregnation or bond
C428S480000, C428S913000
Reexamination Certificate
active
06455135
ABSTRACT:
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a light-transmitting image-recording transparent film to be appropriately used in an overhead projector (referred to as OHP hereinafter), and a method for producing an image-recorded film.
Prior Art
A color image for projection by an OHP on a transparent film has recently been formed by electrophotography. In the method, a black toner and color toners are allowed to adhere to a transparent film in accordance with a desired pattern by any of the electrophotographic apparatuses provided by various manufacturers to simply give a color image or the like.
However, when the film for an OHP thus obtained by the method is actually projected, excellent reproduction of a desired sharp image cannot be obtained on a screen. When a color image is projected in particular, there is a problem that the projected image is considerably blackened and grayed compared with the color image directly observed by the naked eye. The impossibility to obtain an excellent, transparent, sharp projected image is mainly caused by the recesses and protrusions of the surface of the toner image formed on the transparent film by electrophotography. That is, since light incident on a transparent substrate supporting the image is scattered and irregularly reflected by the recesses and protrusions on the toner image surface, the amount of the transmitted light in the toner image portion is protrusions on the toner image surface, the amount of the transmitted light in the toner image portion is reduced. Consequently, the blackened and grayed image is projected.
In order to solve such problems and improve the sharpness and transparency of the projected image, several improvements in the image-recording transparent film have been proposed. For example, Kokai (Japanese Unexamined Patent Publication) No. 2-263642 discloses a transparent laminate film comprising a substrate composed of a first transparent resin and a toner-fixing layer composed of a second transparent resin and provided thereon, the second transparent resin having a solubility parameter of 9.5 to 12.5 and a storage elastic modulus (G′) of 10 to 10,000 dyne/cm
2
, and the storage elastic modulus of the toner to be fixed being smaller than the elastic modulus of the toner-fixing layer. The toner particles are flatly crushed on the fixing layer by a pressure during fixing, in such a transparent film, and the fixing layer has a good compatibility with the resin contained in the toner. The surface of the toner image can, therefore, be effectively flattened. However, when the fixing operation is conducted on these transparent films without using a releasing agent (releasant) such as a silicone oil, hot offset may occur in the step of forming an image.
On the other hand, a releasing agent such as a silicone oil which is liquid at room temperature may make the surface of the toner-receiving layer, in which an image is formed, sticky. Accordingly, the use of a toner containing wax as the releasing agent and a transparent film capable of being used with the wax-containing toner in combination is proposed. For example, Kokai (Japanese Unexamined Patent Publication) Nos. 5-181300, 6-75418, etc., disclose image-forming transparent films each having a substrate layer and a toner-fixing layer capable of absorbing a wax component. In the former patent publication, the toner-fixing layer has an absorbing layer composed of inorganic particles. In the latter patent publication, the fixing layer is composed of such a resin containing a diene component as a polybutadiene. In these films, the wax bleeding from the toner prevents hot offset during fixing, and the wax having bled from the toner is absorbed after fixing. Consequently, the wax is prevented from remaining on the image surface, whereby deterioration of the image quality caused by the wax having bled can be effectively prevented.
Problems to Be Solved by the Invention
However, the transparent film capable of being used with the wax-containing toner as mentioned above shows no significant effect of the proper toner-fixing layer (flattening the toner image, compatibilizing the toner resin, and the like), and the image quality may not be improved after all. Moreover, for a toner containing no wax, the transparent film has showed deteriorated image quality on the contrary. The deterioration of an image quality is principally caused by a low compatibility of the toner-fixing layer and the toner resin.
That is, an object of the present invention is to provide an image-recording transparent film having a toner-fixing layer with an improved compatibility with a toner resin regardless of whether wax is contained or not, and capable of forming a color image of high quality.
Means for Solving the Problems
In order to solve the problems as mentioned above, the present invention provides an image-recording transparent film comprising a transparent substrate and a toner-receiving layer provided on at least one major surface of the substrate, the toner-receiving layer comprising a light-transmitting resin having a softening point of 90 to 180° C., and from 0.1 to 40 parts by weight of an amide nonionic surfactant based on 100 parts by weight of the light-transmitting resin wherein the surfactant is in a compatible state with the light-transmitting resin.
Mode of Operation
Since the toner-receiving layer (namely a toner-fixing layer) contains the light-transmitting resin having a softening point of 90 to 180° C., toner particles subsequent to fixing sink in the interior of the toner-receiving layer. As a result, recesses and protrusions are effectively prevented from remaining on the surface of a toner image, and the sharpness and transparency of the image is improved. When the softening point is less than 90° C., there is a strong fear that hot offset may occur during fixing the toner. Conversely, when the softening point exceeds 180° C., recesses and protrusions may not be effectively prevented from remaining on the surface of the toner image.
Moreover, the amide nonionic surfactant functions as a compatibilizing agent of the resin for the toner and the light-transmitting resin of the toner-receiving layer, and enhances the compatibility of a wide range of resins. Consequently, the image quality (particularly the lightness and chroma) is effectively improved. The surfactant is contained in an amount of 0.1 to 40 parts by weight based on 100 parts by weight of the-light-transmitting resin.
Furthermore, when the wax-containing toner is used, the surfactant hinders the crystal growth of the wax having bled from the toner during fixing, and prevents the wax from becoming white due to crystallization, preventing the deterioration of the transparency of the image. The surfactant is particularly excellent in exhibiting the effect of preventing decreases in the lightness and chroma in a high color density portion caused by the wax which has become white. The surfactant sufficiently makes the wax display its proper function, namely the effect of preventing offset and a decrease in the smoothness of the image surface caused by the offset, and improves the lightness and chroma of the image.
That is, the image-recording transparent film of the present invention can form a light-transmitting image of high image quality even when a wide variety of toners are used in combination, regardless of the type of the toner resin and regardless of whether or not the wax is contained.
Embodiments
Transparent Substrate
The transparent substrate used in the present invention (merely referred to as a substrate sometimes hereinafter) can be selected from conventional polymer films having a conventional high transparency. A film from about 25 to 175 &mgr;m thick excellent in transparency, heat resistance, strength and rigidity is preferred. A preferred concrete example of the polymer is a polyethylene terephthalate. Other polymers such as a polyolefin, a polycarbonate, an acrylic polymer and a polyvinylidene fluoride may also be used.
Toner-Receiving Layer
It is preferred that the li
Dohgoshi Shigeaki
Kamiyama Koji
Florczak Yen Tong
Kelly Cynthia H.
Shewareged B.
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