Special receptacle or package – For plate or sheet – Fragile or sensitive
Reexamination Certificate
2001-09-20
2004-05-11
Ackun, Jacob K. (Department: 3712)
Special receptacle or package
For plate or sheet
Fragile or sensitive
C073S788000
Reexamination Certificate
active
06732864
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a method for measuring strength of an image forming surface of a planographic printing plate, a planographic printing plate and a packaging structure for planographic printing plates.
2. Description of the Related Art
Planographic printing plates, such as photosensitive and heat-sensitive printing plates, have been widely used in plate-making methods (including xerographic plate-making methods) of recent years to facilitate automation of plate-making processes. Planographic printing plates are generally manufactured in the following manner. Surface treatments such as graining, anodizing, silicate treatment and other chemical conversion treatments are administered, alone or in combination, to a support comprising, for example, a sheet-shaped or coiled aluminum plate. Thereafter, a photosensitive or heat-sensitive layer (hereinafter, these layers will be collectively referred to as “applied films”, a surface of a support on which an applied film has been applied will be referred to as an “image forming surface”, and a surface of a support on which an applied film has not been applied will be referred to as a “non-image forming surface”) is applied onto the support and dried, and then the support having the layer applied thereon is cut to a desired size.
The planographic printing plate is subjected to plate-making processings such as exposure, development, gum coating and the like, set into a printer and applied with ink, whereby characters, images or the like are printed on paper.
Sometimes the planographic printing plates are stacked in a thickness direction to form a stacked sheaf so that the planographic printing plates may be handled with greater efficiency. In this case, it is preferable to protect the image forming surfaces (i.e., applied films) of the planographic printing plates by, for example, contacting the image forming surfaces with papers known as “interleaf sheets” and stacking the planographic printing plates so that an interleaf sheet is disposed between each of the planographic printing plates.
Further, there are also cases in which, depending on the type of image forming surface, the image forming surfaces of the planographic printing plates have enough strength to withstand the kinds of damage that present problems in actual use when the planographic printing plates are packaged (or stacked) without interleaf sheets.
However, no quantitative standards or indices for such strengths of image forming surfaces have been proposed.
Also, when planographic printing plates to which interleaf sheets have been contacted to the image forming surfaces of the planographic printing plates are used in automatic plate-making machines, it is necessary to peel the interleaf sheets from the planographic printing plates. Consequently, efficiency of the plate-making operation can be improved when a so-called plate setter or an automatic plate-making machine having an automatic plate-feed function that automatically peels the interleaf sheets from the planographic printing plates and feeds the planographic printing plates is used.
However, when planographic printing plates and interleaf sheets are alternately stacked in a thickness direction to form a stacked sheaf, surfaces (non-contact surfaces) of the interleaf sheets opposite the surfaces that contact the image forming surfaces of the planographic printing plates come into contact with surfaces of the planographic printing plates (an image forming surface in the case of a planographic printing plate having image forming surfaces on both sides thereof, and a non-image forming surface in the case of a planographic printing plate having only one image forming surface) adjacent to the non-contact surfaces of the interleaf sheets. When the non-contact surfaces of the interleaf sheets strongly adhere to these surfaces of the planographic printing plates, the planographic printing plates are supplied without the interleaf sheets having been peeled therefrom, whereby drawbacks sometimes arise such as the automatic plate-feed operation stopping. For example, when a planographic printing plate is raised by the image forming surface thereof being adsorbed, the interleaf sheet protecting the image forming surface of the adjacent planographic printing plate also adheres to the surface of the opposite side of the planographic printing plate and is raised, resulting in both the planographic printing plate and the interleaf sheet being integrally supplied. Further, when the planographic printing plate is raised by the non-image forming surface thereof being adsorbed, there is the potential for the automatic plate-feed operation to be stopped by planographic printing plates and interleaf sheets adhering to the bottom of the raised planographic printing plate and being integrally supplied with the raised planographic printing plate.
Japanese Patent Application Laid-Open (JP-A) No. 2-25845 discloses an interleaf sheet comprising synthetic pulp mixed paper to which heat pressing has been administered. By forming the interleaf sheet in this manner, peelability of the interleaf sheet with respect to the planographic printing plate is improved and damage to the applied film is prevented.
However, since synthetic pulp is itself expensive, the cost of materials for the interleaf sheet becomes high. Further, since it is necessary to manufacture the synthetic pulp by separating it from general paper, manufacturing costs for the interleaf sheets also become high.
If it were possible to determine that the image forming surfaces of the planographic printing plates have a predetermined strength strong enough to withstand damage when packaged without using interleaf sheets, then it would become unnecessary to use the interleaf sheets and the aforementioned drawbacks would be eliminated.
However, as stated previously, because no quantitative standards or indices for such strengths of image forming surfaces have been proposed, at present, planographic printing plates are generally stacked with interleaf sheets disposed between the planographic printing plates in order to more reliably prevent damage to the image forming surfaces of the planographic printing plates.
SUMMARY OF THE INVENTION
In view of the aforementioned facts, it is a first object of the present invention to obtain a method (hereinafter, “the method”) for measuring strength of an image forming surface of a planographic printing plate, with the method being for measuring quantitative standard of strength by which it can be determined that the image forming surface of the planographic printing plate will not sustain damage in a packaged state. It is a second object of the present invention to obtain: a method for measuring strength of an image forming surface of a planographic printing plate, with the method being for measuring quantitative standard of strength by which it can be determined that the image forming surface of the planographic printing plate will not sustain damage in a packaged state, even without using interleaf sheets; a planographic printing plate with which damage to an image forming surface thereof in a packaged state can be prevented by strength of the image forming surface being measured by the method for measuring the strength of an image forming surface of a planographic printing plate; and a structure for packaging the planographic printing plates.
The method of the present invention comprises the steps of: contacting, with an image forming surface to be measured, a member expected to contact the image forming surface of the planographic printing plate in a packaged state; sliding, relative to each other and in a direction along the image forming surface, the planographic printing plate including the image forming surface to be measured and the member expected to contact the image forming surface of the planographic printing plate, while a predetermined load is applied to the planographic printing plate and the member in a direction substantially orthogonal to the image forming surface
Ackun Jacob K.
Fuji Photo Film Co. , Ltd.
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