U.S. patent application number 10/223140 was filed with the patent office on 2003-01-09 for evacuated jacket for thermal insulation and process for manufacturing the same.
This patent application is currently assigned to SAES GETTERS S.p.A.. Invention is credited to Di Gregorio, Pierattilio, Ferrario, Bruno, Manini, Paolo, Palladino, Massimo, Rizzi, Enea.
Application Number | 20030006025 10/223140 |
Document ID | / |
Family ID | 11444077 |
Filed Date | 2003-01-09 |
United States Patent
Application |
20030006025 |
Kind Code |
A1 |
Manini, Paolo ; et
al. |
January 9, 2003 |
Evacuated jacket for thermal insulation and process for
manufacturing the same
Abstract
An evacuated jacket for thermal insulation comprises a
discontinuous or porous, organic or inorganic filling material
arranged inside an envelope made with at least one multi-layer
barrier sheet (1) of substantially rectangular shape, which
comprises at least one polymeric or inorganic central layer (2)
having barrier properties towards atmospheric gases, an upper layer
(4) and a lower layer (3), both of a polymeric material. The
polymeric material which forms said upper layer (4) and the
polymeric material which forms said lower layer (3) of the barrier
sheet (1) are mutually heat-sealable and said barrier sheet (1) is
folded up so as to superimpose two opposite sides (5, 6) thereof
which are welded to each other by melting said upper layer (4) at
one margin (6) and said lower layer (3) at the other margin (5).
The present invention also relates to a process for manufacturing
said evacuated jacket for thermal insulation.
Inventors: |
Manini, Paolo; (Arluno,
IT) ; Ferrario, Bruno; (Rescaldina, IT) ;
Rizzi, Enea; (Milano, IT) ; Palladino, Massimo;
(Lainate, IT) ; Di Gregorio, Pierattilio;
(Sulmona, IT) |
Correspondence
Address: |
AKIN, GUMP, STRAUSS, HAUER & FELD, L.L.P.
ONE COMMERCE SQUARE, SUITE 2200
2005 MARKET STREET
PHILADELPHIA
PA
19103
US
|
Assignee: |
SAES GETTERS S.p.A.
|
Family ID: |
11444077 |
Appl. No.: |
10/223140 |
Filed: |
August 19, 2002 |
Related U.S. Patent Documents
|
|
|
|
|
|
Application
Number |
Filing Date |
Patent Number |
|
|
10223140 |
Aug 19, 2002 |
|
|
|
PCT/IT01/00053 |
Feb 7, 2001 |
|
|
|
Current U.S.
Class: |
165/135 |
Current CPC
Class: |
B32B 3/04 20130101; B32B
27/06 20130101 |
Class at
Publication: |
165/135 |
International
Class: |
F28F 013/00 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 18, 2000 |
IT |
MI2000A 000287 |
Claims
1. An evacuated jacket for thermal insulation, comprising a
discontinuous or porous, organic or inorganic filling material
arranged inside an envelope made with at least one multi-layer
barrier sheet (1) of substantially rectangular shape, which
comprises at least one polymeric or inorganic central layer (2)
having barrier properties towards atmospheric gases, an upper layer
(4) and a lower layer (3), characterized in that said upper layer
(4) and said lower layer (3) of the barrier sheet (1) are formed of
mutually heat-sealable polymeric materials.
2. An evacuated jacket according to the preceding claim,
characterized in that both the polymeric material which forms said
upper layer (4) and the polymeric material which forms said lower
layer (3) of the barrier sheet (1) are selected in the group
consisting of: polyolefines, poliacrylonitrile, polyvinylchloride
and mixtures or copolymers thereof.
3. An evacuated jacket according to the preceding claim,
characterized in that both the upper layer (4) and the lower layer
(3) of the barrier sheet are made of high density polyethylene or a
copolymer thereof.
4. An evacuated jacket according to any of the preceding claims,
characterized in that said upper layer (4) and said lower layer (3)
of the barrier sheet (1) have a thickness between 20 and 100
.mu.m.
5. An evacuated jacket according to the preceding claim,
characterized in that said upper layer (4) and said lower layer (3)
have a thickness of about 50 .mu.m.
6. An evacuated jacket according to any of the preceding claims,
characterized in that it contains a getter material or device.
7. A process for manufacturing an evacuated jacket according to one
of the preceding claims, characterized in that it comprises the
following steps: preparing one multi-layer barrier sheet having a
substantially rectangular shape comprising at least one polymeric
or inorganic central layer (2) having barrier properties towards
atmospheric gases, an upper layer (4) and a lower layer (3) formed
of mutually heat-sealable polymeric materials; folding up said
barrier layer (1) so as to superimpose two opposite margins thereof
(5, 6) and welding together said margins by melting said upper
layer (4) at one margin (6) and said lower margin (3) at the other
margin (5), obtaining an envelope with two open ends; sealing one
open end of said envelope by welding on itself an edge of the
barrier sheet which is orthogonal to said margins (5, 6); inserting
into the envelope a discontinuous or porous, inorganic Or organic
filling material; evacuating the interior of the envelope; and
sealing the other open end of the envelope by welding on itself the
other edge of the barrier sheet which is orthogonal to said margins
(5, 6).
8. A process according to claim 7 characterized in that, before the
last sealing, a getter material is inserted inside the envelope.
Description
[0001] The present invention relates to evacuated jackets for
thermal insulation, and in particular it relates to an evacuated
jacket comprising an improved envelope, as well as to a process for
manufacturing the same.
[0002] Evacuated jackets are being increasingly used in a number of
fields wherein thermal insulation at temperatures lower than about
100.degree. C. is required. As examples of application of these
jackets, mention can be made of the walls of domestic and
industrial refrigerators, of the beverage dispenser machines or of
the containers for isotherm transportation, for example of drugs or
cold or frozen foods. Further, applications of these jackets in the
building field or in the car industry are being studied.
[0003] As it is known, an evacuated jacket is formed of an envelope
inside which a filling material is provided. The envelope has the
purpose of preventing (or reducing as much as possible) the
entrance of atmospheric gases into the jacket, so as to maintain a
vacuum level compatible with the degree of thermal insulation
required by the application. The filling material has mainly the
function of spacing apart the two opposite sides of the envelope
when the jacket is evacuated, and must have a porous or
discontinuous internal structure, so that its porosities or
interstices can be evacuated in order to perform the thermally
insulating function. This material can be inorganic, such as for
example silica powder, glass fibers, aerogels, diatomaceous earths,
etc.; or organic, such as rigid polyurethane or polystyrene foams,
both in the form of boards and of powders.
[0004] The envelope is made with so-called "barrier" sheets, which
are characterized by their gas permeability being as low as
possible and can be made of a single component but more frequently
are multi-layers of different components. In the case of the
multi-layers the "barrier" effect is conferred by one of the
component layers, or barrier layer, which can be formed of
polymeric materials, such as ethylene-vinyl alcohol copolymers
(known in the literature with the abbreviation EVOH); of polymeric
layers on which a thin layer (generally less than 0.5 .mu.m) of
aluminum or of an inorganic oxide is deposited; or of a metal
sheet, mainly aluminum, having a thickness generally comprised
between 4 and 10 .mu.m. The multi-layer barrier sheet comprises at
least one support layer of a polymeric material having good
mechanical features, particularly plasticity; said layer can be
formed for example of polyacrylonitrile (PAN) or a polyolefine. On
the opposite side with respect to said support layer, the barrier
layer is covered with at least one protection layer, also
polymeric. The polymeric protection layers are commonly made of
polyesters (for example polyethylene terephtalate, normally
abbreviated in PET) or polyamides (for example, Nylon.RTM.).
Multi-layers comprising five, six or even more superimposed layers
are also common.
[0005] The envelope is generally formed of two barrier sheets
having rectangular shape, reciprocally joined along the margins
thereof by means of perimetrical weldings. The so joined margins of
the barrier sheets form four flanges arranged at the sides of the
resulting envelope. However, the main drawback of the envelopes of
this kind consists exactly in the presence of these flanges, which
are very fragile and their possible fracturing can easily propagate
beyond the perimetrical weldings, causing the permeation of
atmospheric gases into the jacket and thus compromising the thermal
insulating features thereof.
[0006] In other technical fields, for example in food packaging, a
general process for the preparation of an envelope starting with a
single rectangular sheet of plastic material is known, which
enables the reduction of the number of the flanges from four to two
to be obtained. According to this process, whose steps are briefly
illustrated in FIG. 5a-5c, sheet S is rolled up on itself until two
opposite margins M, M', which belong to the same side of the sheet,
meet together (FIG. 5a). Said margins are reciprocally joined by a
longitudinal welding, thus forming a welding flange F which is then
folded over the external surface of the sheet (FIG. 5b). Thus, an
envelope is formed having two opened ends whose sealing,
transversely to flange F, is carried out by inserting the edges
thereof between welding bars. In the two areas wherein these
weldings intersect the flange, the envelope takes on the
conformation shown in FIG. 5c (which has an enlarged scale with
respect to FIGS. 5a and 5b).
[0007] However, this process cannot be applied to evacuated
jackets. As a matter of fact, in the folded position of FIG. 5c,
flange F causes a thickness which reduces the passage of heat from
the welding bars to the underlying polymeric layers of the barrier
sheet and therefore prevents a perfect reciprocal sealing. Further,
because of its stiffness, along the folding lines the barrier sheet
hardly forms sharp corners and can be only curved; a slot
(indicated with L in FIG. 5c) remains in the intersection area
between flange F and the seals transversal thereto, which enables
the passage of atmospheric gases towards the inside of the jacket,
although in a reduced quantity. The smallest gas infiltrations
resulting from this imperfections, which would be acceptable in
other technical fields, are not acceptable in the case of the
envelopes for evacuated jackets.
[0008] Object of the present invention is therefore providing an
evacuated jacket free from said drawbacks and a process for
manufacturing the same. Said object is achieved by means of an
evacuated jacket whose main features are specified in the first
claim and other features are specified in the subsequent claims.
The features of the process are specified in claim 7.
[0009] A first advantage of the evacuated jacket according to the
present invention consists in that its envelope has a very good gas
tightness also at the end seals, although it is made starting from
a single barrier sheet. As a matter of fact, thanks to said support
layer and said protecting layer being formed of mutually
heat-sealable materials having a similar melting temperature, it is
possible that the opposite layers which are joined together by
means of said longitudinal welding belong to opposite sides of the
sheet, so that the resulting envelope is flat in the welding area
and does not comprise a longitudinal flange.
[0010] Consequently, when the edge of one end of the envelope is
inserted between welding bars for the sealing thereof, the heat of
said bars causes the melting of said support and protection layers,
which become soft, thus allowing the welding bars to near each
other so as to eliminate all the slots between the portions of said
edges.
[0011] An advantage of the process for manufacturing the evacuated
jacket according to the present invention consists in that,
simultaneously to the sealing of the envelope ends, the thickness
of the transversal flanges is made uniform by the welding bars. As
a matter of fact, while said bars are nearing each other, the
exceeding material is discharged form the sides because of the
pressure of said bars and can be removed.
[0012] According to a particular aspect of the invention, said
support layer and said protection layer are made of the same
material.
[0013] Further advantages and features of the evacuated jacket
according to the present invention will appear to those skilled in
the art from the following detailed description of one embodiment
thereof with reference to the accompanying drawings, wherein:
[0014] FIG. 1 shows an enlarged cross-sectional view of a barrier
sheet that can be used for manufacturing an evacuated jacket
according to said embodiment;
[0015] FIG. 2 shows a step of the manufacturing of the evacuated
jacket according to said embodiment;
[0016] FIG. 3 shows a complete evacuated jacket according to said
embodiment;
[0017] FIG. 4 shows an enlarged cross-sectional view of a lateral
flange of the jacket of FIG. 3 taken along line IV-IV of the same
figure; and
[0018] FIGS. 5a, 5b and 5c, the last being an enlarged partial
sectional view, schematically show three steps of the manufacturing
of a known jacket.
[0019] With reference to FIG. 1, there is shown that barrier sheet
1 which forms the envelope of the evacuated jacket according to the
present embodiment of the invention is a multi-layer comprising a
central layer 2 provided with barrier properties towards
atmospheric gases and consisting for example of a metal sheet, e.g.
aluminum, having a thickness between 4 and 10 .mu.m.
[0020] Further, said multi-layer comprises a lower layer 3 and an
upper layer 4 suitable for providing support and protection for the
central layer 2, and to enable the heat-sealing of the sheet. In
addition to the good mechanical features, particularly plasticity,
it is required that the materials which form said layers are
mutually heat-sealable. Said materials can be selected in the group
consisting of polyacrylonitrile (PAN), polyolefines, such as
polyethylene, and polyvinylchloride, as well as mixtures and
copolymers thereof. The lower layer 3 and the upper layer 4
suitably have a thickness between 20 and 100 .mu.m, preferably of
about 50 .mu.m.
[0021] According to a particular embodiment of the invention, the
lower layer 3 and the upper layer 4 are made of the same material.
Particularly suitable for this purpose is high density polyethylene
(known as HDPE).
[0022] With reference to FIG. 2, there is shown that the envelope
of the evacuated jacket according to the present invention is made
rolling up said barrier sheet 1 so as to superimpose two opposite
margins 5 and 6 thereof. The superimposition is carried out so as
to contact the lower layer 3 at margin 5 with the upper layer 4 at
the other margin 6.
[0023] Now, with reference to FIG. 3, there is shown that, by
virtue of the mutual heat-sealability of said lower layer 3 and
upper layer 4, the longitudinal welding of the two margins 5 and 6
has been carried out without having to fold the barrier sheet,
therefore the obtained envelope does not have a longitudinal flange
and is flat in the linear zone 7 of the longitudinal welding.
[0024] Subsequently, the open ends along the edges orthogonal to
margins 5 and 6 are sealed, by inserting said edges between welding
bars. Once they have been sealed on themselves, said edges form two
lateral flanges 8.
[0025] Before the last sealing a porous or discontinuous, organic
or inorganic filling material of any known kind, and optionally a
getter material or device are inserted inside the envelope. A
number of getter materials or devices, suitable for chemically
sorbing moisture or other atmospheric gases, are known in the field
and therefore do not need a detailed description.
[0026] FIG. 4 shows an enlarged partial view in cross-section of
one of said lateral flanges 8. In particular, it shows the portion
of said flange which comprises the linear zone 7 of the
longitudinal welding. With reference to said drawing, there is
shown that the thickness of each lateral flange 8 is uniform all
over its length, in spite of the threefold superimposition of the
barrier sheet 1, in the linear zone 7 of the longitudinal welding.
This can be explained considering that in said linear zone 7 the
lower layer 3 and upper layer 4 of the barrier sheet have become
thinner. As a matter of fact, during the step of sealing the
envelope ends, the heat of the welding bars causes said layers to
be melted and to become soft, so that some of the polymeric
material of which they are formed is discharged form the sides
because of the pressure of said bars and can be removed. As it
appears from the drawing, the edges of the envelope ends are
perfectly sealed on themselves and no slot is present. On the
contrary, by the process according to the state of the art which
was previously described with reference to FIG. 5c, the seals in
this area are not perfect, so that the entrance of air inside the
jacket is allowed which compromises the thermal insulation
properties thereof.
* * * * *