Stock material or miscellaneous articles – Web or sheet containing structurally defined element or... – Including a second component containing structurally defined...
Reexamination Certificate
1998-07-02
2001-10-09
Le, Hoa T. (Department: 1773)
Stock material or miscellaneous articles
Web or sheet containing structurally defined element or...
Including a second component containing structurally defined...
C428S327000, C428S335000, C427S487000, C427S493000, C427S508000, C427S521000, C427S541000, C427S542000, C427S558000, C427S559000
Reexamination Certificate
active
06299972
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to a magnetic display sheet and a method there of, and more particularly, to a microcapsule magnetic display sheet having a ultraviolet ray curable resin layer which has elasticity so as to endow the magnetic sheet with impact resistance and durability.
The magnetic display sheet thus manufactured has such properties as softness or stiffness, is very strong against impact and can distinctly record words or pictures.
DESCRIPTION OF THE PRIOR ART
Many methods of magnetic display are well known so far, for example, a method of sealing fine ball-shaped magnetic powders and titanium oxide particles in microcapsules, moving the magnetic powders in the microcapsules to front to make display by a magnetic field force is published recently. The magnetic display sheet used in this method is composed of a transparent front sheet, a back sheet which is not always necessary to be transparent and a microcapsule layer between the said two sheets.
FIG. 5
shows a cross sectional view of the traditional magnetic display sheet. The microcapsule magnetic display sheet
1
in
FIG. 5
is prepared by a process of painting microcapsule dispersoid on a transparent front sheet
1
, then drying it to form a microcapsule layer
31
, and at last sticking a back sheet
21
closely to the microcapsule layer to complete it.
There are some problems in the traditional magnetic display methods now. While using a magnetic pen (magnetic flux density 850±100 gauss) sold on the market to write words or to draw pictures on the microcapsule magnetic sheet shown in
FIG. 5
, the words or pictures are not distinct sometimes and afterimages leave somehow even the words or pictures are deleted.
And according to its constitution, the back sheet
21
is stuck onto t he microcapsule layer
31
in order to protect it, but the microcapsule layer is not very even as the microcapsules have different sizes.
As a result, hollows
22
between the back sheet
21
and the microcapsule layer
31
generate and the hollows
22
result in microcapsules transformed or destroyed gradually inrepeated wording or drawing.
Therefore, the traditional magnetic display sheet does not have satisfactory impact resistance and desirable durability.
And, while sticking the back sheet
21
onto the microcapsule layer
31
for preparing the microcapsule magnetic sheet, a kind of adhesive is pre-coated on the back sheet
21
to stick it onto the microcapsule layer
31
.
But while sticking the back sheet
21
onto the microcapsule layer, the hollows
22
generate inevitably because the adhesive does not match the microcapsules very well in all the case.
And as the adhesive is point-adhered to the microcapsules, the adhesion is not strong enough and as a result, the back sheet
21
is partially or completely separated from the microcapsule layer sometimes.
Furthermore, as the microcapsule sheet
1
with a back sheet stuck thereon is stiff, it is necessary to stick an unwoven cloth instead of the back sheet if a soft microcapsule sheet is necessary.
And as different adhesives are necessary to be pre-painted on the different back materials, namely sheet or unwoven cloth, the different process results in production efficiency down.
Therefore, the inventors of the invention, based on repeated researches, discovered that a microcapsule magnetic sheet with good durability and impact resistance may be obtained by painting liquid ultraviolet ray(UV ray) curable resin on the microcapsule layer
31
and drying it instead of the traditional back sheet
21
.
The reason for the merits can be considered as while painting the UV ray curable resin on the microcapsule layer, no hollows
22
generate and the UV ray curable resin can protect the microcapsule layer well from wording or drawing pressure.
And, production efficiency of the microcapsule display sheet is also essentially improved because the microcapsule display sheet having softness or stiffness can be produced by a process of covering or not covering a sheet onto the coated UV resin only.
The present inventions are the results of these discoveries.
A BRIEF DESCRIPTION OF THE INVENTION
Therefore, the first object of the invention is to provide a microcapsule display sheet which has very good durability and impact resistance, can display stable and distinct words or pictures at normal wording or drawing speed and the recorded words or pictures can be deleted speedily without afterimage left.
The second object of the invention is to provide a method of manufacturing the said microcapsule display sheet.
The third object of the invention is to provide a method for manufacturing a microcapsule display sheet with softness or stiffness by a simple process.
The objects of the inventions are accomplished by the means as follows.
1. Microcapsule magnetic display sheet sequentially provided thereon with a transparent sheet; a microcapsule layer; and an ultraviolet-ray curable resin layer.
2. Microcapsule magnetic display sheet according to item 1, wherein said ultraviolet-ray curable layer is in a thickness of 20 &mgr;m to 500 &mgr;m.
3. A method of manufacturing the microcapsule magnetic display sheet is composed of processes as:
(1) coating microcapsule dispersoids on a transparent sheet,
(2) drying it to form a microcapsule layer and,
(3) coating liquid ultraviolet-ray curable resin on the microcapsule dispersoid layer and irradiating it with UV rays just after coating to harden it so as to form a UV ray curable resin layer.
4. A method of manufacturing the microcapsule magnetic display sheet according to item 3, wherein a film is covered on the coated liquid UV ray curable resin before it is hardened.
5. A method of manufacturing the microcapsule magnetic display sheet according to item 4, wherein said film covered on the UV curable resin is separable.
As the invented microcapsule display sheet is sequentially provided thereon with a transparent surface sheet, a microcapsule layer coated on the surface sheet and a UV resin layer coated on the microcapsule layer, owing to the existence of the UV resin layer, while wording with a magnetic pen at normal wording speed, distinct and clear lines or pictures(or images) can be recorded and while erasing, the wording lines are completely erased and no lines left. And, the microcapsule display sheet is very good in durability and impact resistance.
In the present invention, the UV resin layer with thickness of 20 &mgr;m to 500 &mgr;m protects the microcapsules from pressure, impact or moisture.
According to the method for manufacturing the microcapsule display sheet, coating microcapsule dispersoid on a transparent sheet, drying it to form a microcapsule layer, then coating liquid UV resin on the dried microcapsule layer and irradiating it with UV lamps to harden it, as the liquid UV resin fills into fine gasp between the microcapsules, the capsules are completely protected and that results in good durability and good impact resistance.
In more detail, as no gaps formed between the microcapsules and the UV resin, the wording pressure is shared by the UV resin but not all suffered by the microcapsules.
Also according to the present invention, after coating the liquid UV resin on the microcapsule layer and before hardening it, covering a sheet on the UV resin to make it more smooth and stiff.
While the covered sheet separated the display sheet becomes soft.
REFERENCES:
patent: 4283438 (1981-08-01), Lee
patent: 5057363 (1991-10-01), Nakanishi
patent: 5151032 (1992-09-01), Igawa
patent: 5411398 (1995-05-01), Nakanishi et al
patent: 5674104 (1997-10-01), Ohashi et al.
patent: 5972493 (1999-10-01), Iwasaki et al.
patent: 01085268 (1989-03-01), None
patent: 05069502 (1993-03-01), None
patent: 07059626 (1995-07-01), None
patent: 07182695 (1995-07-01), None
patent: 08297470 (1996-12-01), None
Igaue Sadatoshi
Iwasaki Takashi
Saito Tutomu
Anderson Kill & Olick P.C.
Chemitech, Inc.
Le Hoa T.
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