Note: Descriptions are shown in the official language in which they were submitted.
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This invention relates generally to a laminated film
and, more specifically, to a transpaxent, synthetic
resin film having a printed pattern such as a section pattern
and useful for drafting or tracing purposes.
Because of their excellent tearing or tensile strength
and good transparency, synthetic resin section films are
increasingly used as a substitute for section papers or graph
papers. Since synthetic resin films are poor in pencil take
properties, chemical mat layers containing inorganic fillers are
generally laminated on synthetic resin substrates.
One such a known section film includes a substrate
which is formed of a polyester and whose surface has been
subjected to a corona discharge treatment, a section pattern
printed on the treated surface of the substrate, and a chemical
mat layer which is provided over the substrate to cover the
section pattern and which has been formed by gravure printing of
an organic coating liquid containing a binder and silica.
While this known film is advantageous in that it is
writable with a pencil and the printed section pattern is not
erased during erasure of the written image, the following
problems are found therein. Firstly, the chemical mat layer is
not firmly bonded to the substrate and tends to be removed
therefrom during use. Secondly, the printed section pattern
tends to become unclear due to dissolution, ellution or swelling
of the ink ingredients thereof during the application of the
chemical mat coating liquid.
The present invention has been made with the foregoing
problems of the known section films in view. In accordance with
the present invention there is provided a laminated film
comprising:
a transparent substrate formed of a synthetic resin
~; and having a thickness of 25-100 ~m;
an adhesive layer coated over one slde of said
substrate and having a thickness of 0.1-1 um;
a pattern printed on said adhesive layer;
and
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a chemical mat layer provided over said adhesive layer
to cover said pattern and having a thickness of 5-10 ~m, said
chemical mat layer containing an inorganic filler and a cured
hydrophilic thermosetting resin.
The laminated film according to the present invention
exhibits good pencil take properties and the printed pat-tern is
not erased during erasure of a pencil-written image. Moreover,
the chemical mat layer is firmly bonded to the substrate and is
not removed from the substrate. Additionally, since the
chemical mat layer is formed using an aqueous coating liquid,
the printed pattern is not eluted, dissolved or swelled upon
contact therewith, so that the lines of the printed pattern of
the laminated film are very sharp and clear.
The present invention wil~ now be described in detail
below with reference to the accompanying drawing, in which the
sole FIGURE is a cross-sectional view schematically illustrating
one embodiment of laminated film according to the present
invention.
Referring to the FIGURE, the reference numeral 1
denotes a transparent substrate formed of a synthetlc polymeric
material such as a polyester, a polyamide, a polypropylene, a
cellulose acetate, a polyvinyl chloride, a polystyrene,
polymethacrylate, a methacrylate copolymer or a polycarbonate.
The thickness of the transparent substrate 1 is generally in the
25 range of 25-100 ~m, preferably 38-75 ~rn.
Designated as 2 is an adhesive or anchor layer formed
of a polymeric material. The adhesive layer 2 has generally a
thickness of 0.1-1 ~m, preferably 0.2-0.4 ,um and serves to
improve the adhesion of a chemical mat layer, which is described
hereinafter, to the transparent substrate 1. The adhesive layer
2 is preferably formed of a mixture of ~0-80 ~ by weight of a
polyester resin with 60-20 % by weight of a resin selected from
vinylidene chloride resins and polyisocyanate resins. Examples
of polyester resins include polyethylene glycol terephthalate
and polybutylene glycol terephthalate. Examples of
polyisocyanate resins include those of tolylene diisocyanate-
type, hexamethylene diisocyante-type and diphenylmethane
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diisocyanate-typ. The above polymer mixture is dissolved in a
suitable organic solvent such as a mixture of 40-60 ~ by weight
of methyl ethyl ketone, 20-40 % by weight of toluene and 10-20
by weight of xylene and the resulting solution is coated over
S the substrate 1 to form the adhesive layer 2.
Provided on the adhesive layer 2 is a pattern 3, such
as a section pattern, a logarithmic section pattern, a rule line
pattern, a marginal borderline pattern, printed by, for example,
gravure or offset printing. Any known ink may be used for the
formation of the printed pattern. Both UV-sensitive and UV-
insensitive inks may be used.
~ esignated as 4 is a chemical mat layer containing an
inorganic filler and a cured hydrophilic resin. The chemical
mat 4 layer has generally a thickness of 5-10 lum, preferably
6-8 ~m. The chemical mat layer 4 is obtained by a method
including the steps of applying an aqueous coating liquid
containing a hydrophilic thermosetting resin and an inorganic
filler to form a coat, and heating the coat to cure the
thermosetting resin.
The inorganic filler may be, for example, natural
silica, synthetic silica, colloidal silica, diatomaceous earth,
clay, quartz, talc, calcium carbonate, magnesium carbonate,
titanium oxide, aluminum oxide or aluminum hydroxide. The
filler generally has an average particle size of 2-12 ~m,
preferably 3-7 ~um. The filler is generally used in an amount of
6-10 parts by weight, preferably 7-9 parts by weight per 10
parts by weight of the thermosetting resin.
Illustrative of suitable hydrophilic thermosetting
resins are acrylic resins, melamine resins and phenol resins.
The aqueous coating liquid may further contain a surfactant and
a curing catalyst. The coating liquid is applied on the
adhesive layer 2 to cover the printed pattern 3 by means of, for
example, a roll coater or a bar coater, followed by drying and
heating. The heat treatment is performed at a temperature and
for a period of time sufficient to cure the thexmosetting resin
and generally at 120-140 C for 1-3 minutes, thereby to form the
chemical mat layer 4.
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In the thus constructed laminated film according to
the present invention, the printed pattern 3 and the chemical
mat layer 4 are firmly bonded to the substrate 1 because of the
presence of the adhesive layer 2. Therefore, there is not the
slightest fear of stripping of the chemical mat layer ~ from the
substrate 1 during use. Further, since the chemical mat layer 4
is formed by applying an aqueous coating liquid, the printed
pattern 3 is not deformed or damaged by dissolution, elution or
swelling during the coating of the aqueous coating liquid.
Therefore, the laminated film has very sharp and clear printed
pattern.
As shown in the FIGURE, the laminated film of the
present invention may be further provided with a second adhesive
layer 5 and a second chemical mat layer 6 on the opposite side
of the substrate 1, if desired. By this, the both sides of the
film may be writable with a pencil. These second adhesive and
chemical mat layers 5 and 6 may be formed of the same materials
as those for the adhesive layer 2 and the chemical mat layer ~,
respectively. These layers 5 and 6 may be formed on the
substrate 1 in the same manner as the layers 2 and 4.
The following examples will further illustrate the
present invention.
Example 1
An anchor coating liquid consisting of 50 parts by
weight of methyl isobutyl ketone, 30 parts by weight of toluene,
17 parts by weight of xylene, 3 parts by weight of a polyester
resin and 1 part by weight of an isocyanate resin was applied to
both sides of a polyester film having a thickness of 38 ~m and
dried to form adhesive layers. A section pattern (scales: 1 mm)
was printed on one side of the thus obtained, adhesive layer-
bearing polyester film by gravure printing. Over the both sides
of the resulting film was then applied an aqueous coating liquid
containing 10 parts by weight of a melamine resin, 9 parts by
weight (as solid3 of an acrylic resin emulsion, 26 parts by
weight of silica, 1 part by weight of a catalyst (ammonium
chloride) and 2 parts by weight of a surfactant was then applied
by means of a roll coater. The coated layers were dried and
heated at 130 C to form chemical mat layers each having a
thickness of 5 um, thereby to obtain a laminated section film
having a structure as shown in the FIGURE. The printed section
pattern of the laminated section film was sharp and clear. The
both sides of the section film were good in pencil take and the
images written with a 5H pencil were able to be erased with a
rubber eraser without causing erasure of the printed section
pattern or stripping of the chemical mat layers from the
substrate film.
The invention may be embodied in other specific forms
without departing from the spirit or essential characteristics
thereof. The present embodiments are therefore to be considered
in all respects as illustrative and not restrictive, the scope
of the invention being indicated by the appended claims rather
than by the foregoing description, and all the changes which
come within the meaning and range of e~uivalency of the claims
are therefore intended to be embraced therein.
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