An improved desiccant package for use with double-glazed windows.
The desiccant material is disposed in discrete islands of desiccant
material, between a pair of elongate sheets of flexible material.
The sheets are joined together to contain the desiccant within the
joined sheets, and to prevent the desiccant from migrating away
from the individual islands. Both sheets are impermeable to the
desiccant, but at least one of the sheets is substantially permeable
to moisture. The desiccant package is disposed within an elongate
tubular spacing member for fitting between the two panes of a double-glazed
window. The spacer member has a longitudinal side which faces the
air space between the two panes of the double glazing, and this
longitudinal side is perforated to allow the atmosphere inside the
double glazing to communicate with the desiccant package within
the spacer tube.
1. A double-glazed window assembly comprising:
a pair of mutually spaced-apart window panes mounted in fixed relation;
a hollow moisture permeable spacing tube laterally disposed between
a desiccant package inserted in the length of said spacing tube;
said desiccant package comprising a first elongate sheet of ductile
plural discrete indentations formed in one face of said first elongate
sheet at intervals along the length of the first sheet;
a quantity of desiccant disposed in said indentations;
a second elongate sheet secured to said one face of said first
sheet to form the desiccant package and enclosing each said indentation
and the desiccant therein, so that the desiccant cannot migrate
between indentations along the length of the desiccant package;
said second elongate sheet being substantially permeable to moisture
but being impermeable to the desiccant,
so that the desiccant is retained within the indentations, but
moisture entering the spacing tube from between said panes of the
double-glazed window can pass through the second sheet for adsorption
by the desiccant.
2. The assembly as in claim 1 wherein:
said one face of said first elongate sheet comprises a substantially
flat face interrupted by and surrounding said indentations,
said second elongate sheet has a substantially flat surface contacting
said substantially flat face of the first elongate sheet; and
said first and second sheets are joined together in the area of
all contacting surfaces of the sheets, so that a lateral cut across
the desiccant package can release no more desiccant than enclosed
in any indentation in the path of the lateral cut.
3. The assembly according to claim 1 wherein said sheets are secured
together in the longitudinal edge areas at the side of each sheet.
4. The assembly according to claim 3 wherein said sheets are secured
together by knurling at said longitudinal edge areas.
5. The assembly according to claim 1 wherein said second sheet
is a nonwoven sheet which comprises PVC fibers bonded together.
6. The assembly according to claim 1 wherein said second sheet
comprises a coated paper, such that the coating on the paper can
be bonded with polyethylene.
7. The assembly as in claim 1 wherein said first sheet having
the indentations is of a material impermeable to moisture, and said
second sheet is permeable to moisture.
8. The assembly as in claim 7 wherein said first sheet comprises
a ductile metal having said indentations formed therein.
This invention concerns a desiccant application in sheet form for
double-glazed windows, etc., so that the desiccant is placed between
two sheets which are joined together, and at least one of these
sheets is permeable to gas and/or air, but especially to moisture.
This invention concerns a desiccant application in sheet form for
double-glazed windows, etc., as well as spacer sections filled with
the desiccant application. (The term "application" as
used here is borrowed from the pharmaceutical field, where it refers
to various aggregate states and forms in which a drug may be administered,
e.g., as tablets, liquid, capsules, etc.)
Tubular spacer sections may be made of metal, e.g., steel or a
lightweight metal, especially aluminum. The starting material may
be a metal sheet which is shaped to form a tubular section by rolling
or stamping. The longitudinal edges of the section may either form
a very narrow slit or can be welded or soldered together, so that
in the latter case, a completely closed hollow section is formed.
It is also known that tubular spacer sections can be produced by
extrusion of lightweight metal.
As a rule, the spacer sections are in the form of tubes, so that
the manufacturer fills the tubes with a desiccant for the double-glazed
windows and shapes a frame from the filled tubular sections. The
frame is then combined with two panes of glass to form the double
Filling the spacer section tubes with desiccant is a very time-consuming
and tedious job. It is still generally done by hand, resulting in
losses due to material which escapes, and the desiccant can also
adsorb substantial quantities of moisture from the atmosphere, so
that the adsorption capacity of the desiccant with which the sections
are filled is already limited.
In addition, it is known from German Patent Application No. 2907838
that a spacer frame can be made directly from sheet metal. During
the shaping of the section, the granular desiccant is placed in
a half-open box section mold, and the mold containing the granules
is then folded over to form the final box section mold and closed.
The closed box section is next inserted continuously into a bending
device where the right-angle U-shaped frame sections are formed.
Rectangular frames are then formed from two U-shaped frame sections.
In handling the filled frame sections, it is impossible to prevent
the desiccant from escaping out of the openings at the ends. In
addition, the double-flanged seam is not airtight, so the desiccant
adsorbs moisture from the atmosphere.
The purpose of this invention is to create a desiccant application
which can be protected from exposure to gas or air and moisture
by a simple means and can be handled well.
This goal is achieved according to the features of the main claim.
Additional features which are essential to the invention are described
in the subclaims. This invention is illustrated in greater detail
with reference to the figure.
FIG. 1 shows a cross section through the desiccant sheet (greatly
FIG. 2 shows a top view of the desiccant sheet, partially in sectional
FIG. 3 shows a perspective of the spacer section a tubular piece
filled with the desiccant sheet.
The application according to this invention is designed as two
layers which form a sheet, consisting of bottom sheet 1 and top
sheet 2. The sheets 1 and 2 which are layered one on top of the
other consist of a flexible material and are joined together in
such a way that they will not come apart spontaneously. Preferably,
they are joined in the longitudinal edge area 3 at the side. The
joining may be assured by knurling, stamping and/or gluing or welding.
It may be advisable for all the contact surfaces between the sheets
to be joined in the manner described above. Preferably, a combination
consisting of stamping and gluing is preferred, where the stamping
has grid-like indentations where the two materials are pressed together.
It is important for the desiccant to be between sheets 1 and 2
and at least one sheet 1 or 2 preferably top sheet 2 consists
of a material which is permeable to gas or air and/or especially
to moisture, preferably a porous material, so that atmospheric moisture
can reach the desiccant almost unhindered. On the other hand, the
material must be so impermeable that the desiccant itself cannot
migrate through the material even when the desiccant sheet is subjected
to frequent mechanical stresses. In this regard, a porous fiber
nonwoven sheet which consists of PVC fibers that are bonded together
has proven especially suitable. Another material which is especially
suitable is a preferably surface-treated paper, preferably in a
thickness of 0.05 to 0.07 mm, preferably 0.06 mm, which can be bonded
with polyethylene, for example. When using granular desiccants,
it can also be advantageous to use perforated paper, optionally
airtight, where the perforations are produced just before use. This
possibility facilitates storage of the new desiccant application,
because no special measures must be taken to protect the desiccant
from moisture. In combination with the permeable sheet, an airtight
sheet is preferably used as the second sheet which is preferably
coated with polyethylene. In the example shown here, the impermeable
sheet is sheet 1 which preferably consists of a ductile metal,
preferably aluminum coated with polyethylene, especially aluminum
foil in a thickness between 0.05 and 0.1 mm. The advantage of using
aluminum sheets is that it is very simple to produce the indentations
by known methods, and the bonding with nonwoven sheet 2 leads to
a secure joining of sheets 1 and 2. In addition, the aluminum sheet
assures sufficient rigidity, while nevertheless it has sufficient
moldability so that it can be rolled up to form a tube, for example,
or inserted into a sectional rod. Furthermore, it is also possible
to bend down the preferably knurled edge 3 as shown on the left
side in FIG. 1 for example, or to otherwise shape it in any way
which may be necessary in using the new desiccant application.
The arrangement of desiccant between sheets 1 and 2 is preferably
such that the desiccant does not escape in substantial quantities
when cutting across the sheet. To this extent, the desiccant in
granular or powdered form may be fixed by adhesive forces which
bond the particles to each other and/or to the surface of at least
one sheet (adhesive). According to one particular version of this
invention, the desiccant is packed in loose form, in an arrangement
of small, defined separate or self-contained heaps spaced at some
distance from each other in the form of islands between sheets 1
and 2 so that when cutting the sheet of desiccant, only small quantities
of the desiccant are lost when a cut passes through an island of
desiccant. In this regard, it is advantageous for the bottom sheet
1 to contain small pockets or indentations 4 which project downward
and contain a desiccant 5. As illustrated in FIGS. 1 and 2 desiccant
5 may be granular or powdered, and this invention shows for the
first time a method which was not otherwise possible for using a
powdered or granular desiccant for the purpose described here.
The cross-sectional shape of the new desiccant application is designed
in such a way that it comfortably fits into the hollow space of
a spacer section. It is a simple matter to match the cross-sectional
shape of the desiccant application to the standard cross-sectional
shape of the smallest spacer sectional available on the market,
with the intention of inserting two or more desiccant sheets side
by side into the cavity of a spacer section with a larger cross
The new sheets of desiccant application can be rolled up as such
and packaged in an airtight plastic film for marketing so that it
can be processed directly for use in double-glazed windows when
the spacer frame is assembled. However, the desiccant application
is preferably processed directly in shaping the sections of spacer
tubes. In this connection, it is known from U.S. Pat. No. 3380145
and from German Patent Application No. 2907838 that loose desiccant
can be poured into a U-shaped preform of the spacer tube, for example,
during production of continuous sections. As part of the present
invention, the sheets of desiccant application are inserted continuously
into the preform while it is still open, then the preform is closed
to form the final tube shape and then pieces are cut from the continuous
strand. The new desiccant application then assures that almost no
desiccant is lost during cutting.
This possibility of cutting across the continuous sectional strand
to form pieces did not exist with the given state of the art because
of the danger of loss of desiccant which could then escape out of
the tube pieces. Instead, the tubular spacer sections filled with
desiccant had to be bent and combined directly to form a rectangular
closed frame. This invention, however, allows several cut spacer
tubes filled with the new sheets of desiccant application to be
packaged in airtight films and marketed in this form. In addition,
it is also possible to close the ends of the openings in the tubes,
e.g., with a butyl compound or some other easily shaped material
which can be removed against easily when the closed tubular rod
is processed to produce a frame. This variant according to the present
invention is especially advantageous when closed tubular sections
with welded longitudinal seams are produced in such a way that diffusion
holes are merely stamped in the sheet and the perforations are not
broken through until the frame is produced. Closing or sealing the
ends formed by cutting the pieces in this way assures that the cavity
of the tube pieces will be sealed very effectively against the outside
atmosphere, thus preventing the desiccant in the new sheet form
of desiccant application from taking up moisture from the outside
atmosphere, so that it can be sufficient to package and market the
tube sections as usual and to bend them to form spacer frames at
a later time, preferably according to the method described in European
Patent Application No. 0009703.
FIG. 3 shows a tube section 6 which is closed by longitudinal welded
seam 7. On the longitudinal side which faces the inside of the double
glazing in the spacer frame there are indentations 8 which are preferably
formed by embossing and are perforated by opening them into the
cavity 9 of the tube section when the frame is produced, so that
in this way, the desiccant sheet 10 (shown with a dashed line) which
is in cavity 9 can act in the desired manner on the atmosphere inside
the double glazing. The manner in which the tube 6 is sealed at
the end is not shown, so that the simplicity of the illustration
would not be impaired.
The use of sheets of desiccant application according to this invention
to produce welded spacer tube sections was not self-evident, because
temperatures up to about 150.degree. C. can act on the desiccant
sheets in welding the tubes. The preferred choice of materials for
sheets 1 and 2 and the preferred type of bonding for the sheets
contribute to the fact that the new desiccant application can be
used for this important and especially economical purpose.