Note: Descriptions are shown in the official language in which they were submitted.
2008465
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METHOD OF MANUFACTURE OF EXPANDABLE AND COLLAPSIBLE CELLULAR
SHADES OF SHEER FABRIC
~ Inventor: Paul Swiszcz
,~
Field of the Invention
- This invention relates to a method of manufacture of
an improved cellular window shade. More particularly, the
invention relates to a method of manufacture of an expandable
i and collapsible material for a cellular window shade, which
~ 10 consists of a number of horizontally-extending cells formed
- of fabric strips adhesively bonded to one another, according
to which sheer fabrics not previously suited for manufacture
of such shades may be employed.
Background of the Invention
Processes are known for manufacturing of cellular
shades, in which the body of the shade consists of a number
of identical fabric strips, folded and adhesively-bonded to
one another so as to define cells. Typically, the cells
extend transversely, but they may also be arranged
vertically, or at an angle to the horizontal. When the shade
is raised, the cells are collapsed; when the shade is
lowered, the cells expand. Such shades contain essentially
~- static masses of air, and thus provide useful thermal
insulation.
Conventionally, such shades are manufactured by
creasing strips of fabric lengthwise to define cell
precursors, and using a liquid adhesive to bond tabs thus
formed on each successive strip to the central body portion
of the next strip, completing the cells. U.S. Patent No.
; 4,450,027 to Wendell B. Colson shows a method of and
apparatus for making such shades from continuous fabric strip
~ material. The adhesive bonding techniques employed
q 35 heretofore in the manufacture of such shades have typically
~ involved the positioning of beads of suitable adhesive on
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either the tabs or the central body portion of the next
strip.
Other patents show related techniques. For example,
U.s. Patents 4,677,013, 4,685,986, 4,631,217, 4,677,012, and
~ 4,676,855, all to Richard l~. Anderson, show further methods
of manufacture of cellular shades. For example, the strips
: may be creased to take a Z-shape, and tabs on either side of
the strip are adhesively bonded to the prior and successive
strips to form the coopleted shade structure. See al~o
U.S. patent 4,732,630 to Schnebly, and the U.S. patent
4,849,039 issued July 18, 1989 to Colson et al.
i:~
AlI of these patents and applications thus teach
; adhesive bonding of tabs formed on a strip of material to a
! preceding strip using a liguid adhesive, or in some cases to
' both preceding and successive strips, to form the cells.I This technigue is the most practical known, but has
effectively limited the types of fabrics from which such
,j shades can be made. Specifically, the material comprising
. the shade is normally stacked with the cells in the collapsed
; position while the liguid adhesive cures. In this position,
the adhesive on the tabs of each strip is normally
juxtaposed to the strip from which the tabs are formed, as
well as the strips to which the tabs are to be bonded.
Accordingly, the fabrics have had to have been selected such
that the adhesive does not penetrate the fabric, so that the
tabs from a first strip do not adhere to the strip from which
they are formed, but only to the strips to which they are to
be bonded; i.e., so that the interiors of the cells are not
;; bonded closed.
3 This limitation on the method of forming shades shown
in the patents mentioned above has been such that certain
highly dQsirable ~sheer~ fabricL have not buen usable.
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~ Sheer~ as used in this specification refers to fabrics which
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~' are highly translucent or are substantially transparent to
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visible light Such sheer fabrics are normally relatively
open weave, and are typically woven or knit of monofilament
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~,, 5 thread. When a bead of conventionai adhesive sufficient to
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form a good bond when employed to form cellular blinds of
typical non-sheer materials is placed on these open-weave
sheer fabrics, the adhesive tends to penetrate the fabric,
particularly if pressure is exerted thereon to ensure a good
bond. Thus, if sheer materials are used in the normal
~-~ manufacturing process, the inner walls of the cells tend
mutually to adhere, which ultimately prevents the blind from
, opening properly. This difficulty has in fact prevented
, manufacture of cellular shades of sheer materials, especially
,, 15 fabrics, permeable to liquid adhesives, which would be highly
desirable to many consumers.
. . .
Various methods have been tried for adhesive
~,~, manufacture of such cellular shades using sheer materials.
; 20 Bands of heavier material have been knit into the sheer
material at the locations where the adhesive is applied, to
`1, slow passage of the adhesive therethrough. In most cases
this material was very difficult to handle and roughly twice
as expensive as the plain sheer material. Using a more
viscous adhesive which does not penetrate the fabric also has
proven unsatisfactory.
.
It appears that successful adhesiv_ bonds between
pen-we",a,v,e,,,sheer fabrics, particularly thos,,,e kni oE_woven of
monofila,me,n,t materials, require impregnation and solidifica-
tion of the adhesive, wherein the adhesive actually
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penetrates,through the fabric and then solidifies into a more
or less solid mass encapsulating the fibers. If the adhesive
'.! iS made too viscous it cannot penetrate the fabric. This is
less of a problem with tightly woven conventional fabrics,
wherein the fibers normally have many small "hairy"
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~ sub-fibers, which provide sufficient surface area to which
'~ the adhesive adheres that a good bond can be formed without
encapsulation. To a considerable extent adhesives which do
not permeate the fabric have been successfully employed to
form cellular shades, e.g. according to the Colson and other
patents discussed above, of opaque, non-sheer fabrics. Open-
weave sheer fabrics do not provide sufficient surface area to
allow formatio`n~of a strong non-impregnating bond. Particu-
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larly where the fabric is knit or woven of monofilament
thread which is not ~hairy~, the impregnation mode of
~ adhesion is required to form an effective bond. In either
; case, when the impregnation occurs, the tabs tend to be
~ bonded to both their own and the preceding and/or successive
,s strips, preventing the blind from opening properly.
- 15
U. S. Patent 4,673,600 also to Richard N. Anderson
address ~ roblem. According to this patent, sheer
.,,'J materials can be formed into ~honeycomb~ or cellular shades
; and adhesively bonded by allowing the adhesive to cure while
the cells are in the expanded state. This method is useful
i~ if~ __-settinq adhesives, e.g. hot melt adhesives, are
used. However, this method poses certain constraints on the
design of the cellular shade thus manufactured, and on the
manufacturing processes employed.
~s 25
Su mary of the Invention
Accordingly, it is an object of the invention to
provide a method of manufacture of cellular shades of
~, materials permeable to liquid adhesives, particularly sheer,
~ 30 essentially open-wea__ fabric materials, which may be_knit or_
;i~ woven of monofilamentary thread.
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It is a further object of the invention to provide
such a method which yields a reasonably priced product.
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It is a further object of the invention to provide a
method of manufacture of an adhesively-bonded, expansible and
collapsible cellular material for shades of sheer fabric,
according to which the adhesive bonds are at least partially
cured while the cells are in the collapsed position.
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, According to the invention, the individual strips
making up the cells are creased to define tabs and central
portions of the strips making up the cells. A strip of non-
~ 10 bonding material is then inserted so as to be disposed
- between the tabs and the portions of the preceding and/or
successive strips to which the tabs are to be bonded.
~j Adhesive is then applied to the two tabs, or to the
corresponding positions on the preceding and/or successive
strips, and these assemblies are stacked, whereby the
adhesive on each tab adheres to the body of the preceding
~ and/or successive strip, and so on, forming the shade. This
;~ assembly is exposed to adhesive cure conditions which ensure
that a suitable bond is obtained. This can be done in a
continuous process as shown in Colson U.S. Patent 4,450,027,
.~ and the other patents discussed above. The shade may then be
expanded by stretching it vertically and removing the strips
-o~ of non-bonding material.
:?
Brief Description of the Drawinas
The invention will be better understood if reference
is made to the accompanying drawings, in which:
Figure 1 shows a perspective view of a shade
according to the invention in the open position;
Figure 2 shows a corresponding perspective view of
the shade according to the invention in the closed position;
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- Figure 3 shows a typical problem occurring where
insufficient adhesive has been used to form a suitable bond
between sheer materials;
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Figure 4 shows a typical problem occurring where
excessive adhesive has caused adjacent layers of sheer
i~ materials to adhere to one another;
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- Figure 5 shows a typical prior art construction using
' 10 a non-sheer material;
.
Figure 6 shows an intermediate stage in the process
;~ of the method of the invention;
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Figure 7 shows the shade o~ the present invention
after manufacture in the open position;
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-$ Figure 8 shows the shade of the present invention in
the closed position; and
Figure 9 shows an alternative embodiment of the shade
according to the invention.
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Description of the Preferred Embodiments
As indicated above, Figure 1 shows the shade of the
invention in the shades-open position, that is, wherein the
shade is drawn upwardly letting light flow unimpeded through
an accompanying window (not shown), while Figure 2 shows the
corresponding shades-closed position. As can be seen, the
shade of the invention comprises a number of cells indicated
generally at 10 which extend transversely to the window. In
the Figure 2 configuration the cells are expanded, exhibiting
a generally polygonal cross-section, while in the Figure 1
condition they are shown having been compressed by drawing a
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base member 12 upwardly. The arrangement of draw cords 1
shown controlling the motion of the base member 12 is
strictly schematic and by no means a limitation on the
invention. Preferably, as indicated, the cords pass through
the centers of the cells and are invisible. In the expanded
position of Fig. 2 the cells each essentially retain static
air masses, which serves as very useful window insulation.
The open ends of the cells may move within U-shaped vertical
end caps to assist in retention of air therein.
::.
As can be appreciated, the requirement therefore is
for a cellular structure which can be readily expanded from
the compressed configuration of Figure 1 to the relatively
expanded configuration of Figure 2, all without undue
mechanical complexity or expense of manufacture and while
retaining a pleasing appearance.
,
~ Economical manufacture of such a shade is best
`; accomplished by adhesively joining tabs formed of the edges
of strips of fabric material corresponding to the cells to
corresponding portions of preceding and/or succeeding
strips.
, :,.
Figure 5 shows a conventional prior art construction,
which may be carried out according to the teachings of Colson
,~ ... , _ _ _ _ _ _ _ . _ .. . . . .. . . .. ... . . ........ .. . .
U.S. Patent 4,450,027, in which successive strips of fabric
20 have been creased to define tabs 20a and central portions
20b. The tabs 20a are adhesively bonded to the central
.. ; .... .....
portions 20b by conventional adhesives as at 22. The fabric
used in this prior art embodiment is not sheer and is
essentially impermeable or only slightly permeable to the
adhesive, such that the shade material can be manufactured
simply by put~ting a bead of adhesive on the tabs 20a and
stacking the strips such that they are aligned with the
; 35 central body portions 20b of successive strips. After the
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adhesive has set, the material of the shade is essentially
completed.
According to the present invention, as described
above, it was desired to employ a sheer fabric material which
. is typically translucent or transparent in the structure of
- Fig. 5. Such materials tend to be of open weave construction
to let light pass through freely and are commonly knit or
woven of monofilament synthetic fibers. Such monofilament
fibers are very smooth-surfaced, such that they do not
, present small hairs or sub-fibers to which the adhesive can
bond. The open weave fabrics in general comprise relatively
few fibers. Therefore, in order to form a suitabl~ hond, _th~
_
~; adhesive must penetrate the sheer fabric, such that when it
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~ lS hardens into a mass, it encapsulates the fibers of the
; fabric.
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Applicant finds that in doing so, using the
conventional construction of Figure 5, and using the
adhesives used successfully with non-sheer opaque fabrics,
the adhesive tends to bond the tabs 20a of each strip not
only to the central portions 20b of the successive strip, as
desired, but also to the central portion of the same strip,
which prevents the shade from being opened. Figure 4 shows
this schematically. If an adequate amount of adhesive is
provided to form a substantial bond, some of it is extruded
~, through the open weave of the sheer material when the strips
are stacked to form the bond. A string of adhesive 26 then
tends to ~oin the tabs 20a and the central portions 20b of
each strip, which prevents the shade from opening properly.
~; Figure 3 shows a typical result when a smaller amount of
adhesive is used to try to avoid this problem. Essentially
the adhesive bonds which are formed are very narrow, as shown
at 24, and tend to break, or are nonexistent; either
condition leads to immediate failure of the shade.
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- For similar reasons, modification of the adhesive
viscosity alone is not sufficient to solve this problem. If
the adhesive is made thicker, it does not penetrate and
encapsulate the fabric; if too thin, it tends to diffuse
through the fabric and does not form an adequate bond.
According to the invention, and as shown in cross-
section in Figure ~, a strip 28 of non-bonding material, that
is, a material which does not bond to the adhesive used, is
interposed between the tabs 20a and the central portions 20b
: of the sheer fabric used. The adhesive is then applied as
~ indicated at 32 to the upper surfaces of the tabs, and the
`', assembly made as previously. The adhesive will normally
- pénetraté the tabs 20a and central portions 20b, but does not
bond to the non-bonding strips 28. When the adhesive has
cured, the non-bonding strips 28 can be removed.
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Figures 7 and 8 show the shade formed of a sheer
material according to the invention after removal of the
non-bonding strips 28. As can be observed, the adhesive 30
tends to penetrate the central portions 20b of the strips but
has been prevented from adhering to the corresponding tabs
'~ 20a by the presence of the non-bonding material 28 as shown
in Figure 6. When the shade is opened, as shown in Figure
-;~ 25 8, the adhesive 30 then extends above the central portion of
:s each strip, but does not interfere with the proper operation
' of the shade.
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~ Figure 9 shows an alternative form of Nhoney~omb" or
;$ 30 cellular shade, as described for example in U.S. Patent
4,676,855 to Anderson, which can be manufactured of adhësive-
permeable sheer materials according to the method of the
invention. In this case, the basic member of the cell is a
strip of material 40 creased to define an overall Z-shape,
with tabs 40a on either side of a central section. The tabs
~' of each strip are joined to the central portions of the
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preceding and succeeding strips. If the strips 40 are
formed of a glue-permeable material, adhesive is applied,
and the strips stacked, the tabs 40a will tend to be
adhesively bonded to the strips from which they are formed;
e.g., tab 40a' will tend to be bonded to the same strip 40 at
a point 40b. According to the invention, strips 42 of a non-
bonding material are inserted into the interior spaces of the
: cells before the strips are stacked, to prevent the interiors
of the cells from thus being adhesively bonded closed.
Strips 42 are removed when the adhesive has at least
partially cured. The method of the invention is similarly
applicable to other honeycomb-configuration cellular shades.
~.
The principal steps in the practice of the invention
are simply the formation of the strips by creasing them to
define the tabs and central portions of cell precursors,
insertion of the non-bonding material, deposition of beads or
droplets of liquid adhesive along the tabs or on the
corresponding mating portions of the strips, and stacking a
large number of these assemblies to form the shade precursor.
After exposure of the shade precursor to suitable conditions
for cure of the adhesive, the strips of non-bonding material
¦ are simply removed, yielding the completed structure.
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~ 25 According to the invention, the preferred material
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for the non-bonding strips may be a polyethylene plastic to
which the adhesive does not bond. A nonstick silicone
~ coating on the strips may be desirable in connection with
-~ certain combinations of adhesives and polyethylenes or other
materials for the strip. Numerous other appropriate
materials will occur to those of skill in the art. Various
< sorts of adhesives such as water activated catalyst
~ adhesives, hot melt glues, moisture-curing hot melts and
;' various silicones are all suitable. Adhesives applied dry
and activated by heating after stacking of the strips, with
or without application of pressure, may also prove useful in
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, the future. It will be appreciated that the key is that the
adhesive must penetrate the fibers of the fabric to fully,,
encapsulate them, forming a suitable bond, and must be
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sufficiently viscous to remain in place during the various
~,~ 5 processing steps.
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~,' Removal of the non-bonding strips 28 can be feasibly
, accomplished simply by laborers using their fingers, but
, obviously more mechanized approaches may also be economically
"~ 10 feasible in some circumstances. Applicant does find that
,' certain desirable fabrics are sufficiently permeable to air
' that it is not satisfactory to simply blow the strips of
, non-bonding material out from the cells thus formed.
.
The other details of manufacturing the shade_
/ according to the invention are generally as shown in the
,`~ varlous u.S. Patents and pending applications referred to
,,~ above.
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~ 20 Whlle a preferred embodiment of the invention has
,~ been disclosed and discussed in detail, this is not to be
considered a limitation on the invention, but only exemplary
~ thereof. Accordingly, the invention should not be limited by
'~ ~ the above disclosure, but only by the following claims.
, 25
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