U.S. patent application number 12/305687 was filed with the patent office on 2010-09-16 for thermal insulation elements.
This patent application is currently assigned to BASF SE. Invention is credited to Guenter Matzke, Werner Wiegmann.
Application Number | 20100231109 12/305687 |
Document ID | / |
Family ID | 38561177 |
Filed Date | 2010-09-16 |
United States Patent
Application |
20100231109 |
Kind Code |
A1 |
Matzke; Guenter ; et
al. |
September 16, 2010 |
THERMAL INSULATION ELEMENTS
Abstract
The invention relates to thermal insulation elements comprising
a) a covering layer having a thickness of from 0.2 to 1.0 mm, b) at
least one vacuum insulation panel located on a), c) a further
thermal insulation material, d) a further covering layer.
Inventors: |
Matzke; Guenter; (Diepholz,
DE) ; Wiegmann; Werner; (Rahden-Wehe, DE) |
Correspondence
Address: |
OBLON, SPIVAK, MCCLELLAND MAIER & NEUSTADT, L.L.P.
1940 DUKE STREET
ALEXANDRIA
VA
22314
US
|
Assignee: |
BASF SE
Ludwigshafen
DE
|
Family ID: |
38561177 |
Appl. No.: |
12/305687 |
Filed: |
June 15, 2007 |
PCT Filed: |
June 15, 2007 |
PCT NO: |
PCT/EP07/55933 |
371 Date: |
December 19, 2008 |
Current U.S.
Class: |
312/401 |
Current CPC
Class: |
F25D 2201/14 20130101;
F16L 59/065 20130101; F25D 23/06 20130101 |
Class at
Publication: |
312/401 |
International
Class: |
F25D 23/06 20060101
F25D023/06 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 22, 2006 |
EP |
06115907.5 |
Claims
1. A thermal insulation element, comprising: a) a covering layer
having a thickness ranging from 0.2 to 1.0 mm, b) at least one
vacuum insulation panel located on a), c) an additional thermal
insulation material, d) an additional covering layer.
2. The thermal insulation element according to claim 1, wherein the
covering layer a) comprises metal.
3. The thermal insulation element according to claim 1, wherein the
covering layer a) comprises a polymer.
4. The thermal insulation element according to claim 1, wherein the
vacuum insulation panel b) comprises a core of open-celled rigid
polyurethane foam which is sheathed by a film, evacuated and
closed.
5. The thermal insulation element according to claim 1, wherein the
vacuum insulation panel b) is fastened in an adhesive manner to the
covering layer a).
6. The thermal insulation element according to claim 1, wherein the
vacuum insulation panel b) covers at least 60% of the area of the
covering layer a).
7. The thermal insulation element according to claim 1, wherein at
least 70% of the area of the covering layer a) is covered by a
vacuum insulation panel b).
8. The thermal insulation element according to claim 1, wherein the
additional insulation material is a polymer foam.
9. The thermal insulation element according to claim 1, wherein the
additional insulation material c) is a rigid polyurethane foam.
10. The thermal insulation element according to claim 1, wherein
the vacuum insulation panel b) comprises a core of foamed
melamine-formaldehyde condensation product.
11. The thermal insulation element according to claim 1, wherein
the additional covering layer d) comprises a metal or a
polymer.
12. (canceled)
13. A refrigeration appliance, comprising: a hollow space which is
surrounded by sheet-like thermal insulation elements, wherein at
least one of the sheet-like thermal insulation elements is the
thermal insulation element according to claim 1.
14. The refrigeration appliance according to claim 13, wherein the
thermal insulation elements are arranged so that the covering layer
a) forms the outer surface of the refrigeration appliance.
15. A process for producing thermal insulation elements according
to claim 1, which comprises: ai) fixing a vacuum insulation panel
b) onto the covering layer a), bi) fixing the covering layer d),
ci) introducing a liquid rigid polyurethane foam system into the
hollow space formed in step bi), di) curing the rigid polyurethane
foam formed in step ci).
16. A method of thermally insulating refrigeration appliances,
comprising: incorporating the thermally insulating element
according to claim 1 as a door element or wall element in
refrigeration appliances.
Description
[0001] The invention relates to thermal insulation elements
comprising vacuum insulation panels, refrigeration appliances
produced from these thermal insulation elements and a process for
producing the thermal insulation elements and also refrigeration
appliances produced therefrom.
[0002] Refrigeration appliances play an important role in many
fields. Refrigeration appliances include, for example,
refrigerators, freezer chests, upright freezers, cooling containers
or superstructures of refrigerated vehicles. The refrigeration
appliances usually comprise a hollow space surrounded by thermal
insulation elements within which the material to be cooled being
located. The thermal insulation elements usually comprise two
covering layers between which a thermal insulation material,
usually a rigid polyurethane foam, is located.
[0003] There is an ongoing need to reduce the energy consumption of
refrigeration appliances. One possible way of achieving this is to
reduce the thermal conductivity of the thermal insulation materials
used. One possible way of bringing this about is the use of vacuum
insulation panels, hereinafter also referred to as VIPs.
[0004] Thus, the energy saving potential when using VIPs is about
10-40% compared to conventional, closed-celled rigid polyurethane
foams.
[0005] Such vacuum insulation units generally comprise a thermally
insulating core material, for example open-celled rigid
polyurethane (PUR) foam, open-celled extruded polystyrene foam,
silica gels, glass fibers, loose beds of polymer particles, pressed
milled rigid PUR foam or semirigid PUR foam or perlite, which is
packed in a gastight film, evacuated and heat sealed in so as to be
airtight.
[0006] The use of VIPs in refrigeration appliances is known and has
been described many times. Thus, WO 97/36129 describes VIPs which
have an edge length of at least 40 cm and can be installed in
refrigeration appliances.
[0007] EP 434 225 describes VIPs and their installation in
refrigeration appliances. Here, the VIP is arranged between the
covering layers and surrounded with foam.
[0008] WO 99/61503 describes VIPs which are installed in
refrigeration appliances. Here, they are fixed to the side facing
the interior of the refrigeration appliance by means of an adhesive
and the hollow space between the covering layers is then filled
with a rigid polyurethane foam system.
[0009] A further ongoing requirement is to reduce the usage of
materials in the production of refrigeration appliances. The use of
VIPs enables, owing to their lower thermal conductivity, a
reduction in the thickness of the insulation of the refrigeration
appliances to be achieved. In this way, an increase in the interior
space and thus the useful volume of the refrigeration appliances is
possible at the same dimensions of the refrigeration appliance.
[0010] A further saving has been able to be achieved by reducing
the thickness of the covering layers. However, this is possible
only to a limited extent.
[0011] When filling the hollow spaces of refrigeration appliances
with rigid polyurethane foam systems, flaws and voids are usually
formed. When the thickness of the covering layers is too low, these
flaws show up on the outside. This impairs the esthetics of the
refrigeration appliances and is regarded as a disadvantage.
[0012] It was an object of the present invention to efficiently
produce refrigeration appliances which have a low energy
consumption and a high quality/defect-free appearance, are simple
to produce and can be recycled without problems.
[0013] This object was able to be achieved by the thermal
insulation elements described in more detail below, by means of
which refrigeration appliances can be produced.
[0014] The object was able to be achieved by thermal insulation
elements comprising [0015] a) a covering layer having a thickness
of from 0.2 to 1.0 mm, [0016] b) at least one vacuum insulation
panel located on a), [0017] c) a further thermal insulation
material, [0018] d) a further covering layer.
[0019] The covering layer a) can comprise metal, for example, steel
sheet. In another embodiment of the thermal insulation elements of
the invention, the covering layer a) comprises polymers, in
particular thermoplastic polymers. Preference is given to using
polystyrene or ABS polymers as polymers. As described, the metal
covering layers have a thickness of from 0.2 to 0.5 mm, preferably
at least 0.25 mm and in particular 0.3 mm, and not more than 0.4
mm. In the case of polymer, a thickness of 0.7-1.0 mm is
preferred.
[0020] Preference is given to at least 60%, particularly preferably
at least 70% and in particular at least 80%, of the area of the
covering layer a) being covered with the vacuum insulation panel.
Complete coverage of the covering layer a) is possible, but it is
not preferred because a filling of the corners with foam should be
undertaken to make the refrigeration appliances produced from the
thermal insulation elements stable. In addition, it cannot be
ensured that regions in which the vacuum insulation panels abut and
form hollow spaces which can also not be filled by the further
insulation material c) are formed at the corners or edges in the
production of the refrigeration appliances.
[0021] The covering layer a) can be covered by a plurality of
vacuum insulation panels, but preferably by only one vacuum
insulation panel. Here, the vacuum insulation panels preferably
have an edge length of at least 40 cm, preferably 60.+-.20
cm.times.160.+-.40 cm, and a thickness of at least 5 mm and at most
50 mm. The size of the vacuum insulation panels is preferably
adapted to the size of the refrigeration appliances and should, as
described, be such that at least 60% of the covering layer a) is
covered by only one vacuum insulation panel.
The advantage of using only one vacuum insulation panel b) per
thermal insulation element is, in particular, that the diffusion of
water vapor and the thermal conductivity can be reduced as a result
of the gap-free covering of the covering layer a) and any gaps
which can occur at the outer skin at the boundary between two
vacuum insulation panels are avoided. Due to the size, this
embodiment can be used, in particular, when the thermal insulation
elements are used for producing refrigerators or freezer
chests.
[0022] The production of vacuum insulation panels and the materials
used for this purpose are known. As core materials, preference is
given to using, as described, open-celled rigid polyurethane foams
or foamed melamine-formaldehyde condensation products.
[0023] A process for producing the foamed melamine-formaldehyde
condensation products is, for example, described in EP 220 506.
[0024] The foamed melamine-formaldehyde condensation products can
comprise up to 50% by weight of other thermoset formers which have
been cocondensed. These are preferably condensation products of
compounds comprising amine, amide, hydroxyl and/or carboxyl groups
with aldehydes, in particular formaldehyde. Preferred thermoset
formers are condensation products of substituted melamine, urea,
urethanes, aliphatic amines, amino alcohols, phenols and their
derivatives with aldehydes. As aldehydes, it is possible to use, in
a mixture with or in place of formaldehyde, further aldehydes such
as acetaldehyde, benzaldehyde, acrolein, terephthalaldehyde.
[0025] Furthermore, the foamed melamine-formaldehyde condensation
products can comprise further additives such as organic or
inorganic fillers. As additives, it is possible to use fibers,
inorganic powders such as metal powders, kaolin, quartz, chalk,
further dyes and pigments.
[0026] Since the foamed melamine-formaldehyde condensation products
have only cell struts and no cell walls, they are very easy to
evacuate. Preference is given to using rigid melamine-formaldehyde
condensation products.
[0027] Foamed melamine-formaldehyde condensation products are known
and are marketed, for example, by BASF AG under the trade name
Basotect.RTM.. They are usually produced by partly dissolving a
pulverulent melamine-formaldehyde condensation product in water
comprising salts or surfactants, mixing the resulting paste-like
intermediate with a blowing agent, preferably in an extruder, and
foaming the resulting product by heating, for example in a hot air
oven. The foam can subsequently be heat treated in a heat treatment
apparatus. Foaming is preferably carried out in a temperature range
from 120 to 180.degree. C., and heat treatment is preferably
carried out in a temperature range from 200 to 250.degree. C.
[0028] Suitable rigid polyurethane foams are described, for
example, in EP 1512707. In the production of the open-celled rigid
polyurethane foams, water and/or hydrocarbons are preferably used
as blowing agents.
[0029] In a specific embodiment of the invention, open-celled foams
based on isocyanate having a cell size of less than 100 .mu.m are
used as core material of the vacuum insulation panels. Such foams
can be obtained via aerogels.
[0030] In the production of vacuum insulation panels using rigid
polyurethane foams, the foam is firstly produced in a manner known
per se. The foams obtained are then, if they have not already been
produced as moldings having the desired size, are brought to the
shape which they have as core of the vacuum insulation panel. This
is preferably achieved by sawing to the appropriate board size. The
moldings are then packed in the gastight sheathing, preferably the
composite film, evacuated and heat sealed so as to be gastight.
[0031] It is usual for a getter material to be heat sealed in
together with the core material in order to prevent volatile
substances which outgas later from impairing the vacuum. Getter
materials which can be used are, for example, zeolites, activated
carbons, strongly hygroscopic materials.
[0032] A film is generally used as sheathing material for the
vacuum insulation panels. Preferred films are composite films, in
particular multilayer composite films having a vapor-deposited or
laminated-on metal layer, for example of aluminum. Suitable films
comprise, for example, polyester, polyvinyl chloride, polyolefins
such as polyethylene or polypropylene or polyvinyl alcohol.
[0033] The use of open-celled rigid polyurethane foams as core
material for the vacuum insulation panel is, as described,
preferred. The advantages are firstly that the refrigeration
appliances produced in this way are completely recyclable since no
constituents extraneous to the system are comprised in the
refrigeration appliance. Secondly, the boards can be handled more
easily than pulverulent materials in the production of the vacuum
insulation panels.
[0034] The vacuum insulation panels b) can be fixed to the covering
layer a) by means of adhesives or adhesive tapes.
[0035] As described, the thermal insulation elements of the
invention are used predominantly for the production of
refrigeration appliances. Refrigeration appliances are, for
example, refrigerators, freezer chests, upright freezers, cooling
containers or superstructures for refrigerated vehicles. The
thermal insulation elements of the invention can be used both as
wall elements and as door elements.
[0036] The refrigeration appliances can be produced in various
ways.
[0037] In one embodiment of the production of the refrigeration
appliances, the thermal insulation elements are produced separately
as flat elements and are then joined to produce the refrigeration
appliances. This embodiment is, in particular, preferred in the
case of very large refrigeration appliances, for example cooling
containers or superstructures for refrigerated vehicles. Here, the
covering layers a) and d) can be fixed in place with the desired
spacing and the insulation material c) can be introduced. As
insulation material c), use is made of, in particular, rigid
polyurethane foam whose liquid starting components are introduced
into the hollow space where they cure to form the polyurethane and
at the same time firmly join the covering layers a) and d) to one
another.
[0038] It is in principle also possible to produce the thermal
insulation elements by the continuous double plate process. For
this purpose, the vacuum insulation panels b) are placed on the
moving lower covering layer a), the liquid starting components for
the rigid polyurethane foam are placed on these and the upper
covering layer d) is then applied. The thermal insulation element
obtained can then, depending on the length of the vacuum insulation
panels b) introduced, be cut between the vacuum insulation panels
b).
[0039] In the production of refrigerators or freezer chests,
preference is given to molding the outer covering layer a) and the
inner covering layer d) to form the housing of the appliance and to
introduce the liquid starting components of the rigid polyurethane
foam used as insulation material into the hollow space between the
covering layers. The rigid polyurethane foam firmly joins the
covering layer and thus stabilizes the housing.
[0040] In one embodiment of refrigerators, insulation elements
whose covering layer a) comprises cardboard or polyolefin, e.g.
polyethylene or polypropylene, are used for the rear side where
aesthetic considerations naturally do not play a dominant role.
Otherwise, these thermal insulation elements have the same
structure as described above.
[0041] In a further embodiment of the production of the
refrigeration appliances, it is possible, as described above, for
the thermal insulation elements to be produced on a continuous
double plate unit and, as described in EP 1 075 634, cut to length,
mitered and folded to form the housing of the refrigeration
appliance. Care has to be taken here that the vacuum insulation
panels b) introduced are not damaged.
[0042] The rigid polyurethane foams which are preferably used as
insulation material c) are preferably the customary and known
compounds as are described, for example, in Kunststoff-Handbuch,
Volume 7 "Polyurethane", 3rd Edition 1993, Carl Hanser Verlag,
Munich, Vienna. These compounds are usually produced by reacting
polyisocyanates, preferably diphenylmethane diisocyanate and
mixtures of diphenylmethane diisocyanate with
polyphenylene-polymethylene polyisocyanates, also referred to as
crude MDI, with compounds having at least two hydrogen atoms which
are reactive toward isocyanate groups. The compounds having at
least two hydrogen atoms which are reactive toward isocyanate
groups are usually polyether alcohols and/or polyester alcohols,
preferably ones having a functionality of at least 3. The polyester
alcohols are usually reaction products of polyfunctional carboxylic
acids with polyfunctional alcohols. The polyether alcohols are
usually reaction products of compounds having at least 3 active
hydrogen atoms with alkylene oxides, preferably ethylene oxide
and/or propylene oxide. As compounds having at least 3 active
hydrogen atoms, use is usually made of polyfunctional alcohols such
as glycerol, trimethylolpropane or sugar alcohols, preferably
sucrose or sorbitol, aliphatic amines such as ethylenediamine or
aromatic amines such as tolylenediamine (TDA) or
diphenylmethanediamine (MDA), usually in admixture with its higher
homologues.
[0043] The reaction usually proceeds in the presence of catalysts,
blowing agents and auxiliaries and/or additives. Water is usually
used as blowing agent, most often in combination with inert
compounds which are liquid at room temperature and vaporize at the
reaction temperature of polyurethane formation, known as physical
blowing agents. Customary physical blowing agents are alkanes,
fluoroalkanes and methyl formate. Among the alkanes, pentanes and
in particular cyclopentane have the greatest industrial
importance.
[0044] In the case of the rigid polyurethane foams used as core
material for the vacuum insulation panels, use is in principle made
of the same starting materials as for producing the polyurethanes
used as insulation materials c). However, water and hydrocarbons,
preferably cyclopentane, are predominantly used as blowing
agent.
[0045] The advantages of the thermal insulation elements of the
invention over thermal insulation elements without vacuum
insulation panels are the significantly lower thermal conductivity,
the lower gas diffusion and the ability to reduce the thickness of
the insulation layer and thus save material. The process of the
invention surprisingly also makes it possible to reduce the
thickness of the carbon layer without this resulting in
disadvantages in terms of the aesthetics of the refrigeration
appliances, the stability and the use properties. In addition, the
residence times in the mold can be reduced by up to 50% as a result
of decreasing the thickness of the remaining insulation layer c)
when using rigid polyurethane foam as c) in an appropriate design.
Furthermore, a more useful space can be made available by reducing
the layer thickness at the same external dimensions.
[0046] In the production of the thermal insulation elements of the
invention, the temperature of the tool or the mold can be reduced
down to 23.degree. C.
* * * * *