U.S. patent application number 10/981593 was filed with the patent office on 2005-05-12 for transparent glazing and use thereof in a chilling chamber door comprising in particular a glazing under vacuum.
This patent application is currently assigned to Saint-Gobain Vitrage. Invention is credited to Florentin, Jean-Michel, Hebert, Anne-Sophie, Messere, Rino.
Application Number | 20050100730 10/981593 |
Document ID | / |
Family ID | 9545964 |
Filed Date | 2005-05-12 |
United States Patent
Application |
20050100730 |
Kind Code |
A1 |
Messere, Rino ; et
al. |
May 12, 2005 |
Transparent glazing and use thereof in a chilling chamber door
comprising in particular a glazing under vacuum
Abstract
A transparent glazing unit having at least one viewing area,
combined with an antifrosting adsorbent layer deposited on at least
one surface of the said area, and its use in a door of a
refrigerated enclosure and more particularly a glazed door, the
glazed area of which essentially consists of a vacuum glazing
unit.
Inventors: |
Messere, Rino; (Modave,
BE) ; Hebert, Anne-Sophie; (Compiegne, FR) ;
Florentin, Jean-Michel; (La Ferte Sous Jouarre, FR) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND, MAIER & NEUSTADT, P.C.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
Saint-Gobain Vitrage
Courbevoie
FR
|
Family ID: |
9545964 |
Appl. No.: |
10/981593 |
Filed: |
November 5, 2004 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10981593 |
Nov 5, 2004 |
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09926609 |
Aug 30, 2002 |
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09926609 |
Aug 30, 2002 |
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PCT/FR00/01424 |
May 25, 2000 |
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Current U.S.
Class: |
428/332 |
Current CPC
Class: |
C03C 17/32 20130101;
Y10S 428/913 20130101; Y10T 428/26 20150115; F25D 2201/14 20130101;
C03C 17/22 20130101; Y10T 428/31645 20150401; F25D 23/02 20130101;
Y10T 428/249953 20150401; Y10T 428/263 20150115; Y10T 428/31504
20150401; Y10T 428/31855 20150401; A47F 3/0434 20130101; Y10T
428/31551 20150401 |
Class at
Publication: |
428/332 |
International
Class: |
E06B 003/00; B32B
001/00 |
Foreign Application Data
Date |
Code |
Application Number |
May 25, 1999 |
FR |
99 06586 |
Claims
1-14. (canceled).
15. A transparent glazing comprising at least one viewing area,
wherein the viewing area is combined with an antifrosting adsorbent
layer deposited on at least one surface of said area.
16. The glazing according to claim 15, wherein the layer is
deposited on the surface of the glazing.
17. The glazing according to claim 15, wherein the layer is
deposited on a plastic film and said plastic film is fastened to
the glazing.
18. The glazing according to claim 15, wherein the layer comprises
at least one hydrophilic polymer.
19. The glazing according to claim 18, wherein the hydrophilic
polymer is crosslinked.
20. The glazing according to claim 18, wherein the hydrophilic
polymer is a polymer or copolymer of vinylpyrrolidone.
21. The glazing according to claim 18, wherein the layer further
comprises an organic or inorganic absorbent material.
22. The glazing according to claim 15, wherein the layer in the wet
state has a porosity of between 0.1 and 1000 cm.sup.3/g.
23. The glazing according to claim 15, wherein the layer in the wet
state has pores whose diameter is between 0.05 and 50 microns.
24. The glazing according to claim 15, wherein the antifrosting
adsorbent layer has a thickness of less than 100 microns.
25. The glazing according to claim 15, wherein the glazing is an
insulating glazing unit comprising at least two glass sheets.
26. The glazing according to claim 25, wherein the glazing is a
vacuum insulating glazing unit.
27. The glazing according to claim 21, comprising an inorganic
absorbent material, wherein the inorganic absorbent material is
porous.
28. The glazing according to claim 15, wherein the layer in the wet
state has pores whose diameter is between 0.1 and 20 microns.
29. The glazing according to claim 15, wherein the layer in the wet
state has pores whose diameter is between 1 and 15 microns.
30. A refrigerated door enclosure comprising the glazing according
to claim 15.
31. The glazing according to claim 18, wherein the antifrosting
adsorbent layer is deposited on the surface of the viewing area
which is in contact with a refrigerated environment.
Description
[0001] The invention relates to a transparent glazing unit and its
use in a door of a refrigerated enclosure and more particularly to
a glazed door, the glazed area of which essentially consists of a
vacuum glazing unit.
[0002] The invention will be more particularly described with
reference to doors of refrigerated enclosures in which cold or
frozen products are displayed, but the invention must not be
construed as being limited to products or applications of this
type. This is because the expression "transparent glazing"
mentioned above covers any type of glazing consisting of at least
one glass sheet and/or of at least one sheet of a plastic which are
intended for applications in the motor-vehicle industry, the
building industry or the domestic electrical appliance
industry.
[0003] When products preserved in a refrigerated enclosure have to
remain visible, as is the case in many current commercial premises,
the refrigerated enclosure is equipped with glazed parts which
convert it into a refrigerated "display case", the usual name for
which is "refrigerated sales cabinet". There are several
alternative forms of these "display cases". Some of them are in the
form of a cabinet and then it is the door itself which is
transparent, while others are in the form of chests and it is the
horizontal lid which is glazed in order to allow the contents to be
seen.
[0004] In these types of display cases, it is necessary for the
merchandise to remain perfectly visible to customers so that it is
possible to preselect the merchandise without opening the "display
case".
[0005] When the usual insulating glazing is used, the insulation is
not perfect and the temperature of the surface of the glass sheet
in contact with the ambient atmosphere is often below the
temperature of the dew point, which may result in the phenomenon of
condensation on this surface, affecting visibility.
[0006] The use of vacuum insulating glazing makes it possible to
eliminate this drawback by providing very greatly enhanced
insulation. Such insulation also has the advantage of reducing the
energy costs.
[0007] The French patent application filed in the name of
Saint-Gobain Vitrage under the number FR 97/09772 describes such a
door of a refrigerated enclosure which includes a vacuum glazing
unit. It thus proposes a door of a refrigerated enclosure
essentially consisting of an insulating panel composed of at least
two glass substrates between which a vacuum has been created, which
substrates are separated from each other by studs distributed over
the entire surface and are joined around their periphery by an
inorganic seal. In this way, the conventional insulating glazing
units normally used are replaced with one insulating glazing unit
consisting of at least two glass sheets between which a vacuum has
been created, which we will call hereafter vacuum insulating
glazing. This type of vacuum insulating glazing has, for a total
thickness markedly less than that of the conventional insulating
glazing units, substantially improved thermal insulation
properties.
[0008] Furthermore, the structure of such a vacuum insulating
glazing unit has the advantage of giving it a stiffness and a
strength which are equivalent to those of a single glazing unit of
thickness equal to the sum of the thicknesses of the glass sheets,
that is to say the glass sheets behave as a single sheet whose
thickness is the sum of that of the two glass sheets. In this way,
it is not necessary to combine this type of glazing with a support
frame. Thus, the overall size is greatly reduced and it is very
simple to fit it into the environmental enclosure.
[0009] Such a door of a refrigerated enclosure, essentially
consisting of a vacuum insulating glazing unit, makes it possible
to solve the problem of condensation on the external surface: this
is because the thermal insulation of this glazing unit makes it
possible to obtain an external surface at the ambient
temperature.
[0010] On the other hand, this enhanced insulation means that the
internal surface of the glazing or of the door is at the
temperature of the refrigerated environment, something which
accentuates the condensation phenomenon when the door is opened:
the temperature of the internal surface is such that, in the case
of freezer cabinets, frosting may be seen to form on the said
surface.
[0011] The usual techniques for preventing the condensation and/or
frosting which forms on the internal surface of the doors consist
in blowing heated air over this surface. Whatever the technique
used, the energy cost is high; the cost penalty is even greater in
the case of a vacuum insulating glazing unit, the time required to
remove the condensation and/or the frosting being longer. Moreover,
this longer time due to the very low temperature of the internal
face goes counter to the intended aim which consists in obtaining
an almost permanent area of visibility, including after opening the
door.
[0012] The objective of the invention is thus in particular to
produce a door of a refrigerated enclosure which includes a glazed
area consisting of an insulating glazing unit, in which the
frosting liable to form on the viewing area when the door is opened
can be rapidly and inexpensively removed.
[0013] This objective is achieved according to the invention by a
transparent glazing unit having at least one viewing area, this
area being combined with an antifrosting absorbent layer deposited
on at least one surface of the said area.
[0014] The antifrosting function of the layer means that it
inhibits the formation of water crystals.
[0015] Such a glazing unit, especially when it is an insulating
glazing unit and more particularly a vacuum insulating glazing
unit, can be used in a door of a refrigerated enclosure having at
least one viewing area consisting, for example, of the said vacuum
insulating glazing unit combined with an absorbent layer
advantageously deposited on that surface of the said viewing area
which is in contact with the refrigerated environment.
[0016] It has been shown that such a door, comprising the glazing
according to the invention, makes it possible to prevent the
frosting phenomenon, or more precisely to delay it or at the very
least limit its appearance.
[0017] According to a first embodiment, the antifrosting absorbent
layer is deposited directly on the glass, and more specifically on
that surface of the vacuum insulating glazing unit which is in
contact with the refrigerated environment. This is the surface in
contact with the refrigerated environment when the door is in its
closed position. Such a layer may be deposited by techniques of the
sputtering or coating type, especially of the flow-coating or
deep-coating type, the deposition being carried out before or after
manufacturing of the vacuum glazing unit. Advantageously, an
adhesion primer of the silane type is provided; it is either
deposited beforehand on the glass or at the same time as the layer
is formed, the silanes being introduced into the composition of the
antifrosting absorbent layer.
[0018] According to a second embodiment, the antifrosting absorbent
layer is deposited, for example according to one of the
abovementioned methods, on a plastic film and the plastic film is
itself fastened to the vacuum insulating glazing unit. The plastic
film used is advantageously a polycarbonate film preferably having
a thickness of less than 3 millimetres; this plastic is especially
chosen for its mechanical strength properties. The plastic film is
fastened to the glazing in a sealed manner so that no trace of
moisture can exist between the glass surface and the plastic film.
It may be fastened, for example, by adhesive bonding around the
periphery; the air layer possibly existing between the glass and
the plastic film must then advantageously not exceed 3 mm. The
fastening may also be achieved by means of an aluminium frame
combined with a desiccant and an adhesive, similar to that for an
insulating glazing unit of conventional construction;
advantageously, the air layer between the glass and the plastic
film then does not exceed 10 mm.
[0019] According to an advantageous embodiment of the invention,
the antifrosting absorbent layer consists of at least one
hydrophilic polymer. Such a polymer may be non-limitingly chosen
from the following polymers: a polyvinylpyrrolidone of the
poly(N-vinyl-2-pyrrolidone) or poly(1-vinylpyrrolidone) type, a
polyvinylpyridine of the poly(N-vinyl-2-pyridine) type, of the
poly(N-vinyl-3-pyridine) type or of the poly(N-vinyl-4-pyridine)
type, a polyacrylate of the poly(2-hydroxyethyl acrylate) type, a
polyacrylamide of the poly(N',N-hydroxyacrylamide) type, a
polyvinyl acetate, a polyacrylonitrile, a polyvinyl alcohol, a
polyacrolein, a polyethylene glycol or a polyoxyethylene. It may
also be a copolymer based on two or more of the abovementioned
polymers.
[0020] Preferably, the invention specifies that the layer consists
of at least one crosslinked hydrophilic polymer. Crosslinking the
polymer makes it possible, in particular, to obtain better cohesion
of the layer and thus to prevent any risk of the layer being
dissolved by water, over the long or short term.
[0021] According to a preferred embodiment of the invention, the
hydrophilic polymer is combined with an organic or inorganic
absorbent material, the said absorbent material preferably being
porous.
[0022] An inorganic absorbent material especially improves the
mechanical strength of the layer and more particularly prevents the
formation of scratches. The inorganic function is advantageously
achieved by depositing a mesoporous material (CPG-MCM 41), such as
TiO.sub.2 nanoparticles, or by depositing orthosilicate hydrolysis
condensation products, or other silicon derivatives.
[0023] An organic absorbent material especially allows retention of
the hydrophilic polymer; a polyurethane is used, for example.
[0024] The inventors have thus been able to demonstrate that the
presence of a porous layer which includes a hydrophilic polymer on
the surface of the glazed area allows water to be absorbed. This
principle prevents the formation of water droplets and thus the
formation of a film liable to frost over and affect visibility
through the glazed area. The choice of hydrophilic polymer and of
the porosity in the case of a porous absorbent material make it
possible to control the antifrosting behaviour of the layer. In
particular, increasing the porosity allows the rate of water
absorption and the water absorptivity, as well as the level of
water in microdroplet form, to be controlled.
[0025] According to a preferred embodiment of the invention, the
porosity of the layer is between 0.1 and 1000 cm.sup.3/g. In the
case of a polymeric material, it is advantageously between 0.1 and
100 cm.sup.3/g and preferably less than 20 cm.sup.3/g. It is
preferably between 200 and 1000 cm.sup.3/g in the case of a
mesoporous material. The porosity defines the void volume of the
pores per unit mass of the layer.
[0026] Also preferably, the layer has pores whose mean diameter is
between 0.05 and 50 microns, preferably between 0.1 and 20 microns
and more preferably between 1 and 15 microns. The shapes of the
cavities making up the pores are oval or spherical.
[0027] Whatever the nature of the antifrosting absorbent layer and
the method of producing the latter, it advantageously has a
thickness of less than 100 microns, preferably less than 50 microns
and more preferably less than 35 microns and, in some cases,
preferably less than 25 microns and more preferably less than 20
microns.
[0028] Further details and advantageous characteristics of the
invention will emerge below from the description of illustrative
examples of the invention and of tests carried out.
[0029] As described above, a door or a refrigerated sales cabinet
was produced. It consists especially of a vacuum insulating glazing
unit in order to form the viewing area and of a door frame, for
example made of metal. This frame may especially support all the
mechanical systems of the handle and hinge type, as well as the
seals which seal against the walls of the refrigerated
enclosure.
[0030] The insulating glazing unit consists of two glass sheets
between which a vacuum has been created. The glass sheets are
separated from each other by studs distributed over the entire
surface of the glazing and are joined together around their
periphery by a seal of inorganic adhesive. Such a vacuum insulation
glazing unit is, for example, produced according to a technique as
described in Patent Application EP 645 516.
[0031] According to the invention, a polycarbonate film having a
thickness of 2 millimetres is fastened to the vacuum insulating
glazing unit by means of an adhesive forming a strip with a
thickness of 1 millimetre around the periphery of the glazing.
Thus, an air cavity is formed between the glazing and the
completely sealed polycarbonate film. This complex is produced in
such a way that the trapped air is dry. The film is fastened to
that side of the vacuum insulating glazing unit which is intended
to face the inside of the refrigerated enclosure when the door is
in its closed position.
[0032] Before attaching it, the polycarbonate film is coated with
an antifrosting absorbent layer, this being deposited so as to face
the inside of the refrigerated enclosure when the door is in the
closed position. The layer thus deposited forms a polymeric porous
three-dimensional network based on polyvinylpyrrolidone and
polyurethane.
[0033] Measurements were carried out on the layer in the wet state
using transmission electromicroscopy; these measurements allow the
thickness of the layer and the size of the pores to be checked. The
thickness of the layer is equal to 14.5 microns and the pores have
a mean diameter varying from 1 to 8 microns.
[0034] Tests were carried out on. various types of doors. These
doors are fitted onto refrigerated sales cabinets within which a
temperature of -28.degree. C. is maintained. The cabinets
themselves are placed in an atmosphere at a temperature of
25.degree. C. The tests consist in opening the door for a period of
3 minutes and a period of 12 seconds. The 3-minute period simulates
the average time needed for this type of cabinet to be stocked up
in the morning. The 12-second duration simulates the average time
needed for a consumer to take one or more products.
[0035] The measured results are the times needed for satisfactory
visibility through the door to return, that is to say the times
needed to remove the condensation and/or frosting.
[0036] The first door tested, A, has an insulating glazing unit
consisting of three glass sheets. The second door tested, B, has a
vacuum insulating glazing unit.
[0037] The third door, C, is that according to the invention that
has just been described.
[0038] The results are given in the table below:
1 3-min opening 12-s opening A 8 min 20 s 1 min 15 s B 31 min 10 s
1 min 40 s C 0 s 0 s
[0039] From these results it is clearly apparent that door C,
produced according to the invention, prevents the formation of
frosting.
[0040] Another test was carried out under similar conditions. Only
the nature of the layer differs in this second example. This second
example consisted in depositing a layer consisting only of a
hydrophilic polymer; this hydrophilic polymer was based on
polyvinylpyrrolidone, having a molecular mass of 1,300,000 g/mol
and diluted to 10% by mass in ethanol. The composition thus
obtained was then deposited on the glass by flow coating.
[0041] Tests such as those described above, consisting in opening
the door for a period of 12 seconds and for 3 minutes, were carried
out. In both cases, there was no sign of any frosting on the
viewing area of the door.
[0042] The presence of the absorbent layer therefore prevents the
formation of frosting when the door is opened under normal
operating conditions.
* * * * *