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| Resin-based synthetic papers are generally
divided according to their manufacturing method into
two broad categories: film synthetic paper and fiber
synthetic paper. Currently, film synthetic paper is
more commonly used. Several different methods have been
devised to produce a paper that is similar in appearance
to regular paper. |
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(1) Internal
Paper-manufacturing Method
Filling material and additives are added to synthetic
resin, and following fusion and kneading in an extruder,
a film is formed by extruding the material through a
die slit. With this method, the relatively thin fused
resin pushed through the die slit can be treated in
one of two ways. In the non-oriented film method, the
output resin is simply hardened by cooling and prepared
for commercialization. In the biaxial oriented film
method, the fused resin is cooled temporarily, and then
heat is added to re-soften it. It is then stretched
in the longitudinal and cross directions, forming a
film. As part of the biaxial orienting film method process,
during stretching, tiny holes (micro-voids) may or may
not be encouraged to form, producing two different kinds
of products.
Yupo Corporation's YUPO®
is a leading example of synthetic paper with micro-voids
produced by the biaxial stretching film method.
(2) Surface Coating
Method
Just as with ordinary coated paper,
by adding a layer of pigment coating to a plastic film
(including synthetic paper produced by the internal
paper-manufacturing method above), this method can add
properties such as whiteness, opacity, and suitability
for writing and printing to the product.
(3)
Surface Treatment Method
By chemically or physically treating the synthetic resin
film surface, qualities such as suitability for writing
and printing or opacity can be added with this method. |
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(1) Synthetic Pulp
Paper
Replacing pulp with resin fibers made primarily from
synthetic resin, this is a synthetic paper made with
an ordinary paper machine with binder added.
(2) Spunbond Paper
In this method, synthetic resin is dissolved and injected
through a nozzle, randomly lining up endless fibers
formed as like synthetic fabrics. The fibers are then
fused thermally in some areas, creating interfiber bonding.
The whiteness and opacity of paper is achieved through
the light-scattering properties of the fibers themselves
and the irregular reflection caused by gaps that form
between the fibers during production. This kind of paper
is characterized by its superior strength, but it is
not as smooth and is of somewhat lower suitability for
writing and printing.
This kind of paper is generally placed in the category
of "unwoven fabrics," but depending on the
product it can be accepted as a synthetic paper in the
market. |
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By laminating film on the surface of
conventional paper, this method adds mechanical strength
and water-resistance to the paper. By including tiny
holes (micro-voids) in the film, the paper can be made
to be nearly as fit for printing as conventional paper.
Since the inner layer is paper, its water-resistance
and strength is inferior to that of film synthetic paper. |
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