DE102009002799A1 - Cooling device i.e. household refrigerator, has refrigerated goods shelf with photo-catalytic surface layer that is turned toward refrigerating chamber and activated by radiation in visible wavelength of specific range - Google Patents

Abstract

The device has an inner lining (3) that lines a refrigerating chamber (1) and a refrigerated goods shelf (7) with a photo-catalytic surface layer turned toward the refrigerating chamber. The photo-catalytic surface layer is activated by radiation in a visible wavelength ranging from 380 to 780 nm and includes a photoactive material i.e. titanium dioxide. The inner lining and the refrigerated goods shelf form a carrier layer that is made of polystyrene, glass or acrylonitrile butadiene styrene. An independent claim is also included for a method for producing a shaped part for a cooling device.

Description

The The invention relates to a refrigeration device, in particular Domestic refrigeration appliance, according to the generic term of Patent claim 1 and a method for producing a refrigerator according to claim 11.

To provide a self-cleaning surface, it can be coated with photocatalytic material. Irradiation with light can decompose organic-chemical impurities on the surface. The surface remains clean and antibacterial. Such photocatalytic surface layers are according to the EP-B-0 590 477 and the DE 196 54 199 C2 applied to a support and activated by UV light.

From the WO 2007/072165 A2 a generic refrigeration device is known in which the cooling space bounding an inner wall and a plug-in tray are provided with a photocatalytic cover layer. On the top wall of the cooling chamber, a light source is arranged with which the photocatalytic cover layer can be activated in order to accelerate as a catalyst oxidation of organic deposits on the surfaces facing the cooling space. For this purpose, the refrigerator is illuminated by the light source when the refrigerator door is closed.

The from the WO 2007/072165 A2 known photocatalytic cover layer can be activated with light whose wavelengths in the UV range, ie in a wavelength range of about 365 to 380 nm. To activate the photocatalytic cover layer, therefore, UV lamps must be installed in the cold room. Such UV lamps have a lower life compared to the light sources commonly used in the refrigerator and are much more expensive compared to conventional light sources. In addition, the UV radiation may adversely affect the plastic material of the inner lining of the refrigerator as well as therein Kühlgutträger.

The The object of the invention is a refrigeration device, in particular household refrigeration appliance, as well as a method to provide for its production, wherein the effect of the photocatalytic Cover layer is improved in a simple manner.

The The object is achieved by the features of claim 1 or claim 12 solved. Preferred developments of the invention are in discloses the dependent claims.

According to the Characteristic part of claim 1 is the inventive photocatalytic cover layer designed so that it is exposed to radiation in the visible wavelength range, in particular in one Wavelength range from 380 to 780 nm, can be activated. To activate the photocatalytic cover layer can therefore usually for lighting a cold room used lighting means, such as LEDs.

Prefers The photocatalytic cover layer can not only by radiation in the visible wavelength range, but in addition also by radiation in the UV range, that is in one Wavelength range of about 365 to 380 nm are activated. In this way, the radiation spectrum within which the photocatalytic topcoat can be activated on one area extended from 365 to 780 nm, which gives a freer selection the usable light sources results. Thus a sufficient effect of the photocatalytic material is ensured it is preferred to design the photocatalytic cover layer such that in the visible wavelength range and / or in the UV range the Activity of the photocatalytic material used is at least 30%, preferably at least 50%.

As a photoactive material can be used in the photocatalytic cover layer TiO ₂ , which is harmless in terms of compatibility with food. To produce the photocatalytic cover layer, the photoactive material is introduced in powder form into a base material, such as polystyrene.

The photocatalytic cover layer has to be designed with regard to the wavelength range requirements specified above. In this case, the photoactive material, in particular TiO ₂ , may preferably have a specific surface area which is in a range from 250 to 350 m ² / g. Investigations have shown that, in particular when using a TiO ₂ powder with a specific surface area of 300 m ² / g, sufficient activity is obtained for radiation both in the UV range and in the visible range. This corresponds to a grain size of 15 nm of the TiO ₂ crystallite used, which are agglomerated in the powder of the photoactive material.

For an effective activation of the provided in the refrigerator Self-cleaning surfaces is one possible homogeneous light distribution of importance. The light sources used can in particular in a discontinuous Operation work to a deterioration of quality to avoid the refrigerated goods.

The molding according to the invention may comprise a carrier, which together with the photokata lytic cover layer forms a two-layer structure. The molded part is preferably the carrier. The cover layer and the carrier may preferably have the same material properties. Thus, it is advantageous if the base material of the photocatalytic cover layer as well as the support is deep drawable. The base material of the photocatalytic cover layer and the material of the support preferably belong to the same material family or are identical to them. As a result, sufficiently large laminate or binding forces between the cover layer and the support can be achieved, whereby peeling of the cover layer from the support is prevented.

The photoactive material can be used to produce the photocatalytic Cover layer powdery in a base material, preferably Polystyrene, are introduced. In this case, the photoactive Material already integrated in the plastic granules of the base material be.

Of the Carrier can be made of polystyrene, high impact polystyrene, glass or be made of ABS.

For the case that the photocatalytic cover layer also with light a wavelength from the UV range can be activated additional protective measures are used, during a photocatalytic process, the plastic carrier to protect. It is preferred if between the Carrier and the photocatalytic cover layer an additional Intermediate layer is switched, which protects the wearer from damage UV radiation or protected by the photocatalytic process.

The Shaping of the molding can be done in a thermoforming process. Before such a deep-drawing process, in a first production step, such as by extrusion, preferably co-extrusion, the photocatalytic Cover layer are connected to the carrier. The so provided plate-shaped semi-finished is then for a deep drawing process brought to a deformation temperature and then fed to a thermoforming device in which the shaping of the molding takes place.

Alternatively, the shaping in the deep-drawing process can be carried out with omission of the photocatalytic cover layer. In this case, the cover layer can be applied only after the shaping of the cooling chamber facing surface. Such a subsequent coating can be carried out by a per se known PVD process, by applying a corresponding liquid paint, by powder coating or by a sol-gel process. Alternatively, the subsequent coating of the already deep-drawn molded part can be carried out by a subsequent plasma treatment or plasma coating with a TiO ₂ suspension or by a siloxane coating with embedded TiO ₂ particles.

following is an embodiment of the invention with reference to the accompanying Figures described.

It demonstrate:

1 in a schematic side sectional view of a refrigeration device;

2 a material structure of a, the refrigerator of the refrigerator limiting inner lining;

3 the material structure of an arranged in the cooling compartment insert tray;

4 the material structure of a cover plate arranged in the cooling space;

5 the activity of the photocatalytic cover layer as a function of the wavelengths of the light source used; and

6 and 7 in each case schematic diagrams illustrating methods for producing the molded parts according to the invention.

In the 1 is a side sectional view of a refrigerator with a refrigerator 1 shown by means of an interior paneling 3 is limited. The refrigerator is through a door 4 closed. At the bottom of the refrigerator 1 there is a slide-in tray 7 for vegetables or the like. The fridge 1 is also by storage plates 8th divided into individual cooling compartments.

The interior lining 3 is made in known manner from a plastic material in the deep drawing process. The inset shell 7 on the other hand can be made in a plastic injection molding process, while the cover plates 8th Glass elements can be.

The material structure of the interior lining 3 , the insertion shell 7 and one of the storage shelves 8th is in the 2 . 3 and 4 shown. Consequently, both the interior trim 3 , the slide-in tray 7 as well as the cover plate 8th at her, the fridge 1 facing surfaces a photocatalytic cover layer 9 which is activatable by light to oxidize organic deposits on their surfaces.

Like from the 2 shows, is the photocatalytic cover layer 9 on a dimensionally stable carrier layer 15 applied. The carrier layer 15 is in the case of interior trim 3 usually one colored. According to the 2 has the carrier layer 15 the interior lining 3 a material thickness d ₁ in the range of 4 to 5 mm and is the carrier layer 15 made of polystyrene. The photocatalytic cover layer 9 has a material thickness d ₂ in the order of less than 1 mm.

The photocatalytic cover layer 9 has as photoactive material TiO ₂ particles, which are incorporated in a polystyrene base material. In that sense, the top layer 9 with the polystyrene base material and the carrier layer 15 carried out the same material, which can be achieved in a simple manner high binding forces between the two layers.

In contrast to that in the 2 shown two-layer construction is in the 3 the inset shell 7 manufactured in three-layer construction. In this case, the photocatalytic cover layer 9 with the interposition of a protective layer consisting of inert material 11 on the dimensionally stable carrier layer 15 applied. Both the topcoat 9 as well as the carrier layer 15 can be made essentially from the same material as already from the 2 be made explained.

In the 4 is the material structure of one of the cover plates 8th Their glass surfaces are also coated with a photocatalytic topcoat 9 are coated. As a carrier layer 15 Here serves the actual glass element of the cover plate 8th ,

The photocatalytic cover layers 9 the interior lining 3 , the insertion shell 7 as well as the storage plates 8th According to the invention are designed such that they are not only activated by UV radiation in a wavelength range of 365 to 380 nm, but also in a wavelength range greater than 380, in particular greater than 400 nm, are also activated in the visible wavelength range.

The for the production of the photocatalytic cover layer according to the invention 9 used TiO ₂ powder in this case has a specific surface area of 300 m ² / g and may also be provided with additional dopants in order to be activated in the above-mentioned wavelength ranges can.

To illustrate the effect of the topcoat 9 is in the 5 a diagram showing a photocatalytic activity of the TiO ₂ powder used over the wavelength of a radiation source. Consequently, at a wavelength of 300 nm, an optimum of activity results with maximum activity of the TiO ₂ powder. As the wavelength increases, the activity of the TiO ₂ powder decreases to about 40%. Investigations show that until such an activity, the mode of action of the photocatalytic cover layer 9 can still be maintained.

For activating the photocatalytic cover layers 9 in the refrigerator are in accordance with the 1 a series of light sources 13 provided, in particular in the visible wavelength range, the photocatalytic cover layers 9 can irradiate. The light sources 13 can by a discontinuous operation with the refrigerator door closed the refrigerator 1 illuminate, whereby negative influences of the light on the quality of the goods can be reduced or avoided.

In the 6 and 7 is in each case a method for producing a as inner lining 3 usable molding illustrates its material structure in the 2 is shown. According to the 6 In a method step I, as a semifinished product, a two-layer blank section with the photocatalytic cover layer produced in a two-layer extrusion is produced 9 and the carrier layer 15 provided.

In a subsequent preheating step II preceding the deep-drawing process, the blank part is placed in a heating field 17 preheated to a deformation temperature. After reaching the deformation temperature, the preheated blank part in the deep drawing step III in a deep drawing device 19 promoted. In the deep drawing process, an upper deep-drawing tool 21 under compression of the blank part up to a predetermined Tiefziehspaltmaß on the lower tool part 23 introduced, whereby a shaping of the blank is done.

In the manufacturing process of 6 becomes the photocatalytic cover layer 9 even before molding in the thermoforming device 19 on the carrier layer 15 applied. The photocatalytic cover layer 9 is therefore exposed to mechanical and thermal stresses during the thermoforming process, so that a correspondingly robust design of the cover layer 9 is required. Against this background, in the process of 6 a photocatalytic cover layer 9 used, whose base material is polystyrene, in which the photoactive TiO ₂ particles are introduced.

In the 7 is also a process for making a as inner wall 3 usable molding with two-layer structure illustrated. Unlike the manufacturing process of 6 here becomes the carrier layer 15 without photocatalytic cover layer 9 subjected to a thermoforming molding. Only in the subsequent process step IV, the photocatalytic cover layer 9 applied to the already deep-drawn molding. With such a subsequent coating, the pho tocatalytic covering layer 9 be applied by means of a production technology easy to carry out PVD process, by means of liquid paint or powder coating or by means of a sol-gel process. In the case of subsequent coating, therefore, mechanical or thermal stresses on the cover layer can occur 9 be prevented due to the deep drawing process. The cover layer is therefore manufacturing technology with greatly reduced effort on the interior trim 3 be applied.

1

refrigerator

3

interior panelling

7

Slide-shell

8th

cover

9

photocatalytic topcoat

11

interlayer

13

light sources

15

backing

17

heating field

19

Deep-drawing device

21 23

Thermoforming molds

d ₁ -d ₃

thicknesses

I-IV

steps

QUOTES INCLUDE IN THE DESCRIPTION

This list The documents listed by the applicant have been automated generated and is solely for better information recorded by the reader. The list is not part of the German Patent or utility model application. The DPMA takes over no liability for any errors or omissions.

Cited patent literature

• - EP 0590477 B [0002]
• - DE 19654199 C2 [0002]
• - WO 2007/072165 A2 [0003, 0004]

Claims (14)

Refrigerating appliance, in particular household refrigerating appliance, which has at least one molded part ( 3 . 7 . 8th ), about one the cold room ( 1 ) of the refrigerator lining interior trim ( 3 ) or a refrigerated goods tray ( 7 ), which at its the refrigerator ( 1 ) side facing a photocatalytic cover layer ( 9 ), characterized in that the photocatalytic cover layer ( 9 ) Is activated by radiation at least in the visible wavelength range, in particular in a wavelength range of 380 to 780 nm. Refrigerating appliance according to claim 1, characterized in that the photocatalytic cover layer ( 9 ) additionally in the UV range, that is in a wavelength range of 365 to 380 nm, can be activated. Refrigerating appliance according to claim 1 or 2, characterized in that the activity of the photocatalytic cover layer ( 9 ) in the visible wavelength range and / or in the UV range greater than 30%, in particular greater than 50%. Refrigerating appliance according to claim 1, 2 or 3, characterized in that the photocatalytic covering layer ( 9 ) has a photoactive material, especially TiO ₂ . Refrigerating appliance according to claim 4, characterized in that the photoactive material has a specific surface area of 250 to 350 m ² / g, in particular 300 m ² / g. Refrigerating appliance according to one of the preceding claims, characterized in that the molded part ( 3 . 7 . 8th ) a carrier layer ( 15 ), which together with the photocatalytic cover layer ( 9 ) forms a two-layer structure. Refrigerating appliance according to claim 6, characterized in that the molded part ( 3 . 7 . 8th ) the carrier layer ( 15 ). Refrigerating appliance according to claim 6 or 7, characterized in that the carrier layer ( 15 ) is made of polystyrene, glass or ABS. Refrigerating appliance according to one of the claims 4 to 8, characterized in that photoactive material in a, in particular thermoformable base material, such as polystyrene, is introduced. Refrigerating appliance according to one of claims 6 to 8, characterized in that between the photocatalytic cover layer ( 9 ) and the carrier layer ( 15 ) an intermediate layer ( 11 ) is provided of inert material. Refrigerating appliance according to one of the preceding claims, characterized in that the radiation energy of a light source ( 13 ) radiation emitted in the refrigerator has a peak value at least in the wavelength range of the visible light. Method for producing a molded part ( 3 . 7 ) for a refrigerator according to one of the preceding claims. A method according to claim 12, characterized in that prior to shaping (III) of the molded part ( 3 . 7 ), such as deep drawing, in a first production step (I) the photocatalytic cover layer ( 9 ) on the carrier layer ( 15 ), for example by means of extrusion, in particular co-extrusion, is coated. A method according to claim 12, characterized in that after the shaping (III) of the molded part ( 3 . 7 ) the photocatalytic cover layer ( 9 ) on the carrier layer ( 15 ) is applied.