Note: Descriptions are shown in the official language in which they were submitted.
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SPECIFIC~TION
We have previously disclosed (corresponding application now
issued in Belgium Patent No. 801,240) thermally activated bookbind- -
ing elements and apparatus for binding such cover elements to a
plurality of sheet elements provides a superior binding system. As
those skilled in the art of plastics, and related book cover materials
are aware, limitations are inherent in the use of plastic materials
in conjunction with thermally activated adhesives. The application of
temperatures sufficiently high to activate the binding adhesive si-
multaneously may cause a degradation of the cover material imme-
diately underlying the adhesive being heatedO Accordingly, we have
found that in typical binding applications, a preferred cover material
comprises paper, cloth, and/or related products that are relatively
insensitive to the application of sufficient heat to melt the thermally
activated adhesive. We have also previously disclosed that plastic
covers may be employed in combination with heat reactivatable
adhesive by utilizing the heat reservoir characteristics of the heat-
reactivatable, or l'hot melt~' cement, the complications of such a
two-stage processing system render desirable a method of thermally
binding books which is non-destructive of plastic, preeerabl~r trans-
parent, covers in the conventional one-stage binding operation. To
our knowledge, no successful transparent cover binding element has
been constructed capable of thermal binding in a one-stage process
and which is capable of assembly and binding in the field by a person
having no special skills.
In accordance with the present invention, a binding for a
plurality of sheets of paper cornprises a back cover member integral
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with a back spine, a front flap integral wi~h the back spine, thermally
activatable cement thermally cemented to the back spine, and a front
cover member secured to the front flap by a strip, jof pressure sensitive
adhesive with the edge of the front cover being spaced from said cement
The back spine or backbone element is preferably in~egral with the back
cover and front flap by flexible hinge lines, and the thermally activatable
adhesive or cement is disposed between these hinge lines. The backbone
or spine is preferably constructed of a material such as cloth or paper
which is inherently resistant to degradation by heat, and the pressure~
sensitive adhesive of the front flap is spaced from the above-mentioned
thermally activated adhesive such ~hat a clear plastic cover may be
assembled ~o the flap by manually pressing the cover to the pressure -
sensitive area thereof, Subsequent heating of therthermally activatable
adhesive in a bookbinding apparatus such as described and claimed in
our above-mentioned Belgi~ patent is then readily accomplished without
degradation of the transparent cover and a complete, bound, book of
sheets results. ~.
It is, accordingly, an object of the present invention to provide a
simple, and yet highly efficient, transparent cover which is not tempera~
ture degradable in normal useO The resulting bound book provides an
exposed fly-leaf or title page which is particularly pleasing for office ;~
binding of management reports, and the like, in a fool-proof mannerO
ON THE DR~ WINGS .
Figure I is a partial end-elevational view of a cover constructed
in accordance with a first embodiment of my invention; ;:
Figure 2 is a partial end-elevational view of the cover shown
in Figure I in assembled relation with bound sheets; ;~
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Figure 3 is an isometric view of the back member of
the covcr shown in ~igure 1 with release-~aper in a partial state
of disassembly;
Figure ~ is a partial end-elevational view of a modified
form of ~he present invention; and
~igure 5 is an isometric view of a cover constructed in
accordance with the structure shown in ~igure 4.
A first embodiment of the invention is shown in Figures
1, 2 and 3. There, a back member is generally indicated at 10
and has a longitudinally extendmg flexible hinge line 11. Thermal-
ly activatable adhesive, commonly termed "hot melt" adhesive 12
is secured to ~he back member 10 either directly by application
thereto in a molten state, or, as here shown, by adherence to a -~
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paper backing member 13 which is in turn fixedly secured to the
back member 10 by way of pressure-sensitive adhesive 14 or other ~ s~-
mechanical attachment means. The rear flap 15 of the back mem-
ber 10 is illustrated as secured to the back cover 16 of ~he binding
by adhesive 16a or the like and the front flap member 17 is
secured to fron~ cover member 18 by adhesive 18a With the com-
ponents assembled as illustrated in ~igure 1, the binding may be
folded into a "U" configuration as illustrated in Figure 2 and a
plurality of sheets 20 may be secured therein by the passage of
heat through the back member 10 in the direction of arrow 21, in
accordance with the disclosure in our above-identified Belgian patent~
In accordance with the structure above described, a
convertible, or alternative, cover form may be provided, Separate
supplies of intercllangeable cover members 16 and 18 may be
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proYided, along with a supply of universally applicablc back mem-
bers 10, Tlle cover members 16 may be opaque, in a large
number of possible colors and of substantially any material, such
as plastic, paper, cloth. or the like. The cover 18 may be iden-
S tical to cover 16, or, in the form illustrated, preferably comprises
a transparent plastic material either clear or in some attractive
color. The stock of back members 10 with p~essure-sensitive
layers 22 and 23 covered by an inert release paper 24, as shown
in Figure 3 for example, may be sold as a separate item for
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lû assembly in the field with covers of opaque or transparent charac-
teristic. The covers 16 and 18 may be ~uite hea~-sensitive as is
typically the case with transparent ma~erials, but this sensitivity ; ;~
is not adversely affected by the thermal binding operation since the
heat from that operation passes through the back member 10, as at
21, xather ~han through the cover mennbers 16 and 18. By con-
structing the back member 10 of cloth, paper, or similar matexial
that is relatively insensitive to and non-degraded by short term
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edge exposure to heater temperatures on the order of 300 F
typically employed in the thermal activation of the adhesive 12, a
transparent cover is provided even though ~he ~ransparent materials
such as polyvinyl chloride, polyester and acetate typically used in
l~ookbinding degrade at temperatures substantially below the above- ~;
mentioned temperature, Accordingly, hy means OI this invention,
a transparent cover is provided and at the same time a wide- ;
~S ranging alternate form cover system is achieved. We have found
from practice that a wide range of materials are acceptable for
use in accordLmce with O~II invcntion. Clear plastic front covers
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m~y successfully be construc~ecl of polyvinyl chloricle, polyester,
or acetate, typically in thicknesses on the order of . 005". As
those familiar with plastic sheet and film products are aware,
many of these materials struc~urally degrade at temperatures sub-
S stantially below 300 F and, accordingly, if covers were constructed
for use with thermally activatable cement of a conventional form
activated by positioning the cover over a hea~er operating at a
temperature on the order of 300 F, completely unsatisfactory cover
members would result and, further, in many instances the plastic
1n material would melt onto ~he binding machine heater element dis-
abling the machine. Utilization of the transparent plastic cover ~'materials is achievable, accordingly, by the present system through
attachment of such plastics to a paper, buckram, cloth, or similar
back member which is relatively non-degradable at the heater ;
temperatures above mentioned. Attachment of the plastic to the
back member may successfully be accomplished by a large number
of pressure-sensitive, or other, adhesives. We have found that
pressure-sensitive tapes sold by 3M Company under the product
designations Y-911 and Y-920 are very satisfactory. These pro-
ducts are typically marketed in a strip ~/8" wide coated on both ~-
sides with a pressure-sensitive adhesive and carrying release
papers on both sides. One side of the tape may conveniently be
pressure-secured to one edge of a transparent plastic front cover ;
member which may then be stored over periods OI time and subse- ~ ~-
quently assembled to a back cover prior ~o a sheet binding opera-
tion merely by removing the remaining release paper and pressing
the exposed pressure-sensitive surface against the front flap of the
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back membcr. Such a system provides extreme flexibility since
stores of differ~nt color, texture, or thickness of front covers may
be accomplished and a final binding may be tailored to the particu-
lar binding job at the time of assembly. It will be understood,
however, that bindings may be constructed by providing an adhesive
between the transparent front cover and the front flap during an
initial fabrication step in which the thermally activatable adhesive ~ -
is placed on the back spine and the front cover is cemented to the
front flap. In these circumstances, of course, the cement
employed between the front cover and the front flap may be of
substantially any conventional form since manual field assembly is
not contemplated.
A second embodiment of the invention is shown in
Figures 4 and 5. There, the back cover 116 is integral with the
lS back spine l10 and the front flap 117, and is provided with a hot
melt cement 12 directly thermally applied as shown. The front
cover 118 is provided with a pressure-sensitive adhesive layer
118a which may carry a release paper 124 as shown in Figure 5
permitting storage of front covers 118 in various colcrs and
thicknesses as above described~ Assembly of the parts shown in
Figure 5 is accomplished by pressing the exposed pressure-sensi-
tive layer 118a against the upper surface of the front flap 117 to
provide an assembled book cover as shown in Figure 4. The
cover shown in Figure 4 is employed in the binding of sheets 20
substant~ally identically in the fashion shown in Figure 2. It will
be observed that in the embodiment shown in Figure 1, the back
member 10 may have inherent stiffness with flex or hinge lines 11,
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or, alternatively, it may comprise a relatively generally flexible
material such as cloth. In the latter event, utilization of a rela-
tively stiff paper backing 13 under the thermally ac~ivatable cement
12 will provide a stiIfncss to the back member not necessary in
structures such as shown in Figures 4 and 5 where the portion or :
back spine 110 is the relatively stiff cover material itself.
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