The present invention relates to a glittering-reflecting sheet paper material and relative production method.
Numerous types of paper are known with a special look and/or finish for producing attractive luminous, reflecting, iridescent effects and similar, and which are used, for example, for packaging, illustrations, quality advertising, etc.
For example,
Such paper, however, often poses problems at follow-up processing stages, in particular printing, on account of the way the material is treated and/or any elements added to the material to achieve the desired characteristics.
It is an object of the present invention to provide a paper material of original aesthetic characteristics, and which at the same time is fully compatible with conventional printing methods.
According to the present invention, there is provided a sheet paper material, as defined in enclosed claim 1.
The granules of mica or other reflecting inorganic substance of equivalent properties have a predetermined particle size, and are quantity controlled to avoid interfering with any follow-up printing processes.
More specifically, the particle size of the mica employed ranges approximately from 2 to 150 µm, preferably from approximately 10 to 120 µm, and more preferably from approximately 20 to 80 µm; and approximately 1 to 1000 granules of mica per cm2 of surface are used, depending also on the desired effect.
The layer incorporating the mica granules comprises a substantially transparent binding composition, in which the mica granules are incorporated. Preferably, the binding composition is a polymer composition of natural and/or synthetic latex, e.g. acrylic, butadiene or similar, and comprises approximately 5 to 30 parts by weight of mica.
In a preferred embodiment, the sheet paper material is glazed on both opposite surfaces, and each surface is associated with a respective layer incorporating a dispersion of granules of mica (or other equivalent substance) as described above.
There is also provided a method of producing a sheet paper material, as defined in enclosed claim 10.
More specifically, said surface-treatment step is performed off and downstream from the continuous paper machine.
Preferably, said surface-treatment step is performed after (but may even be performed before) the step of glazing the same surface.
The granules employed at the surface-treatment step are of such particle size and quantity as not to interfere with follow-up printing processes, and, in particular, have a particle size ranging approximately from 2 to 150 µm, preferably from approximately 10 to 120 µm, and more preferably from approximately 20 to 80 µm; and the quantity of granules employed ranges approximately from 1 to 1000 granules per cm2 of surface.
The granules of mica (or other equivalent substance) are applied in a substantially transparent binding composition, in which said granules are incorporated.
Preferably, the binding composition is a polymer composition of natural and/or synthetic latex comprising approximately 5 to 30 parts by weight of mica, and is applied to the surface of the paper material in a quantity ranging approximately from 1 to 5% by weight.
The step of producing a web of paper material on a continuous paper machine, and the glazing step are conventional and therefore well known; and the type of paper on which the surface-treatment step is performed may also be conventional.
The advantages of the present invention will be clear from the foregoing description : that is, there is provided a paper material of distinctive aesthetic appearance (derived from combining glazing and mica granules), and which at the same time is perfectly suitable for top-quality printing (using any known method). The presence of mica granules in paper materials in accordance with the invention, in fact, has surprisingly been found to have no negative effect on printing quality.
Other natural or synthetic substances with light-reflecting characteristics equivalent to mica may be used instead, though mica would seem to give the best results.
Clearly, changes may be made to the paper material and relative production method as described herein without, however, departing from the scope of the present invention as defined in the accompanying Claims.
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