EP0989781B1 - Multiple glazing and manufacturing method of plate glass coated in order to manufacture multiple glazing - Google Patents

Abstract

The full coating of an electrically conductive transparent material on one of the glass sheets is deactivated within a sheet edge zone incorporating the contact area with a distance piece. An Independent claim is given for a method for producing glass sheets with an electrically conductive coating for multi-sheet glass panes. The method consists of coating glass with such a coating, cutting it into sheets with dimensions corresponding to those of the pane, and deactivating the coating within the sheet edge zone.

Description

The invention relates to a multi-pane insulating glass for devices with a reduced interior temperature relative to the ambient temperature, in particular for glazed doors of refrigerated and freezer cabinets. It consists of at least two spaced about the same size discs, the distance is held by a peripheral edge near spacer. One of the two outer panes is provided on its side facing the space between the panes with an electrically conductive, transparent coating. The invention further relates to a process for the production of coated flat glasses for such insulating glasses.

In particular, refrigerators and freezers and cabinets have glazed doors with Mehrscheibenisbliergläsern of the type described above. It delimits the cold area in the interior against the higher ambient temperature.

In the case of refrigerated and, in particular, freezer furniture, condensate formation frequently occurs due to the temperature difference between the interior and the surroundings. The condensate of humidity, which is reflected on the pane, obstructs or impedes the view of the refrigerated goods in the interior. In order to prevent this or to quickly remove the precipitated condensate again, the pane of the multi-pane insulating glass facing the exterior is heated in the devices on the market. This is realized by a heatable, electrically conductive, transparent coating on the inside of the pane, ie on its side facing the space between the panes. Such a coating consists for example of doped SnO ₂ , which is applied for example by hot spraying and baked.

For this purpose, the glass pane is cut to the desired level prior to coating, and a mask covering the edge area is applied to the pane, so that the subsequent contact surface with the spacer is kept free of the coating. This is necessary in spite of the usual bonding with non-conductive adhesives in the cured state, to prevent the metal spacers used when heating the Disk to electrical jumps on the spacers comes, which are under tension, which can lead to overheating.

EP 0 712 101 A1 relates to an alarm glass pane with an electrically conductive, partially reflecting surface layer, which has been completely removed again in a partial area by mechanical removal, in which a likewise electrically conductive breakage detector is arranged.

EP 0 807 611 A1 relates to a glass unit with an optical coating which has a defined reflection characteristic in the visible range of the light spectrum. Opto-coating refers to a coating "that has an eye-perceptible effect in the visible range." The glass unit has a composite rim that is clear of the opto-coating from the outset or has been freed from it.

It is an object of the invention to provide a Mehrscheibenisolierglas that reduces the formation of condensation, which can be produced with low process cost and is safe to the outside electrically isolated.

The object is achieved by a multi-pane insulating glass according to claim 1 and by a method according to claim 4 for the production of coated flat glass panes for such Mehrscheibenisoliergläser.

Notwithstanding the hitherto known heatable multi-pane insulating glasses for devices with a reduced interior temperature relative to the ambient temperature, the electrically conductive transparent coating is applied over the entire surface in the production of flat glasses for producing the multi-pane insulating glasses according to the invention. It can be applied over the entire surface to commercially available flat glass, which is only cut to the special dimensions when coated.

This eliminates the previously necessary step of applying the mask before coating. Also, discs of many different small formats need not be coated.

The transparent coating, for example of doped tin oxide, z. B. with fluorine (SnO ₂ : F), z. B. applied by hot spraying or dipping.

Such coated flat glasses with sheet resistances of, for example, about 10 Ω / □ to 40 Ω / □ are marketable. Other suitable coating materials are, for. As silver or tin-indium oxide (ITO). It is advantageous that the coatings exemplified here are not only electrically conductive, but also heat-reflecting.

Usually, such coatings are referred to their scratch resistance from hard (high scratch resistance) and soft (low scratch resistance) layers.

Hard are z. For example, the doped tin oxide coatings, Ag layers, and ITO layers represent soft layers. Hard-coated disks are used here because they are more suitable for being thermally toughened, and because multi-layer insulating glasses are usually made from tempered disks.

According to the invention, the originally fully applied electrically conductive transparent coating is circumferentially deactivated in the edge region, ie. H. no longer electrically conductive, including the contact surface to the spacer. This makes it possible that commercially available spacers, for example made of metal, can be used to ensure the distance between the panes of the multi-pane insulating glass, without it comes when heating the disc to electrical jumps on the spacer.

In addition to the deactivated direct contact surface with the spacer, the deactivated surface still extends at least 2 to 3 mm on both sides beyond the contact surface with the spacer. Since the spacer does not directly adjoin the edge of the disc, but recirculates slightly recessed towards the edge of the rim to form a joint for insulation and sealing material, the deactivated surface extends to increase the electrical safety preferably to the edge of the disc.

In conventional disk formats and conventional spacer sizes, the width of the deactivated zone is usually between 5 mm and 10 mm, preferably between 8 mm and 10 mm.

Various methods are suitable for deactivating the described partial area of the coating.

For example, soft layers, for. B. silver layers, by grinding by means of a rotating grinding head with z. B. remove corundum or diamond.
Such mechanical removal is not advantageous for hard coatings on glass since many disks break.

To deactivate the coating, that is, to cancel its electrical conductivity, the coating does not necessarily have to be completely removed it is enough to destroy it so that it is no longer electrically conductive.

This is done according to the invention by applying a glaze or enamel to the area of the coating to be deactivated and subsequently heating the pane. The glaze or enamel is baked at temperatures below the softening point of the glass of the pane, whereby the glass composition of the glaze or enamel melts, penetrates the coating and destroys its conductivity and stably bonds to the surface of the glass pane.

Glazes usually consist of a transparent or translucent glass composition which is applied to the article in finely divided form, for example a paste, by the known techniques, such as, for example, screen printing, pad printing, decalcomania or brush application. The finely ground glass powder is often referred to as glass frit. Enamels are glazes containing coloring ingredients like pigments. Since the color impression does not matter here, pigment-free glazes are usually sufficient. Typical layer thicknesses are 5 μm to 30 μm.

The glass frit must have a lower melting point than the glass to which it is melted. The baking temperatures thus depend on the composition of both the glass frit and the glass sheet. Typical firing temperatures and durations on soda-lime glasses are 650 ° C to 720 ° C and 1 to 10 minutes. The fire also serves to volatilize organic carrier materials which are used as auxiliaries for the application of the glaze or the enamel. Preferably, the stoving of the glaze is performed simultaneously with the process of thermal tempering. As a result, the process complexity is minimized by the additional process step of deactivating the layer. The method described is particularly preferred for deactivating hard layers.

The method described for the production of coated flat glasses with deactivated edge region, consisting of the process steps of full surface coating, cutting, deactivating the edge region, is part of the production process of the multi-pane insulating glass, which can be completed in the usual way.

In the multi-pane insulating glass according to the invention, the transparent electrically conductive coating, which is deactivated as described in partial areas, is located on the side of one of the two outer panes facing the space between the panes.

The circumferential peripheral spacer contacts the coated disc in the region of the deactivated coating and is bonded to the discs in the usual way, for example with the butyl (polyisobutylene) currently used in multi-pane insulating glass production. The material is not electrically conductive. The sealant used are, for example, customary sealants based on polysulfide. The Randumfassung is realized in a known manner, for example with an adhesive tape, z. B. an insulating tape.

The cut edges are generally lined only. In a specific embodiment of the invention, the edges of the coated disc have a facet cut on the coated side. With this cut, the conductive layer is also milled off in this area. Such oblique milling removes both soft and hard layers easily.

The heating of the coated disc takes place via the contacting of applied silver conductor tracks. They are preferably applied by screen printing and then dried. The power is supplied via insulated cables, which are provided with cable lugs and attached to a printed on the coating trace. The cables are guided in a known manner through the spacer.

Sufficient heating can be realized with very different sheet resistances. Thus, with appropriate adaptation of the voltage, film resistances between 5 Ω / □ and 100 Ω / □ are possible.

The power required for heating can be achieved by voltages between 10 V and 240 V depending on the sheet resistance. Although a voltage corresponding to the mains voltage has the advantage that no transformer is needed, it is disadvantageous, however, that parts which are exposed to 220 V or 230 V, for example, are accessible when the disc breaks. Preference is given to voltages between 12 V and 48 V, since in this case there is no danger potential even in the case of defects of the insulating glass.

Of course, the thickness of the disc also plays a role. Usual thicknesses are 3 mm to 5 mm, preferably 3 mm to 4 mm, both for the front pane and for the pane facing the interior and possibly further panes.

For thermal insulation between a cold interior and a warmer environment, the multi-pane insulating glass consists of two or more panes. Usually two slices are sufficient, but three slices can be useful.

The one or more spaces are usually with air or for further thermal insulation with a noble gas, eg. As argon filled.

The transparent electrically conductive coating may be on the inside, d. H. on the side facing the space between the panes, from the next pane to the interior of the appliance or from the pane, the front pane, which is furthest away from the interior.

Condensation and precipitation of the condensate at the disc occurs when the dew point is exceeded.

On the windscreen, this can happen if, despite the isolation through the multi-pane insulating glass front window on its outside is so cold that the dew point is below. When that happens, of course, depends on the relative humidity of the environment. By heating the disk can be achieved that the disk temperature is above the dew point.

When the door is closed, the pane adjacent to the interior has, on the side facing the interior, a low temperature which depends on the interior temperature. Since the dew point is at a lower temperature, the window is fog-free. When the door is opened, however, the dew point of the environment can be reached below on its cold side, so that condensed air humidity is deposited on the cold side of the door.

While the first-described formation of horseshoes can often be avoided or at least reduced by an effective insulating glass arrangement, the latter case occurs much more frequently.

Therefore, preferably, the pane closest to the interior of the device has on its side facing the space between the panes, the transparent conductive coating over which it is heated, usually to a higher by about 1 ° C to 4 ° C temperature than without heating.

This often does not prevent fogging when opening the door, but speeds up the disappearance of the fitting after closing.

Since the heating of the disc takes a relatively long time for conventional services or a rapid heating requires a very high power, it is preferable in both variants described to heat the respective disc in continuous operation.

Reference to the drawing with Figures 1, 2a and 2b and the embodiment of the invention will be explained in more detail.

They show:

FIG. 1:

not to scale a part of a cross section through a Zweiperibenisolierglas a device with respect to the ambient temperature reduced indoor temperature

FIG. 2a:

a supervision and

FIG. 2b:

a cross-section through a provided with a partially deactivated conductive coating glass, both not to scale.

In detail:

Figure 1 shows a part of a cross section through a Zweiperibenisolierglas a device with respect to the ambient temperature lowered indoor temperature. The two-disc insulating glass shown consists of the two transparent glass panes 1 and 2, which are held by the spacer 3 made of stainless steel at the desired distance from each other. In the interior 4 of the hollow profile is a desiccant in granular form. Of the Gas exchange between the desiccant and the argon-filled gap 5 between the discs 1 and 2 is ensured by the opening 6. The spacer 3 is set back relative to the edge of the disc by about 3 mm to a joint for receiving the insulating and sealing compound 7, a polysulfide elastomer, z. B. Thiokol ^® , by means of which the discs 1 and 2 are glued together and sealed to the outside, to form. The spacer is glued to the two discs by means of the adhesive 8 made of polyisobutylenes. Both the adhesive 8 and the sealant 7 are electrical insulators. The adhesive tape 9 represents the edge surround and serves as edge protection. The edges are just lined. Another edge processing is not necessary. Glass pane 2 is the pane closer to the surroundings, the windscreen. Glass pane 1 is the device interior not shown spaced next. On its inner side, ie the side facing the space between the panes, it is provided with a transparent, electrically conductive coating 10 made of SnO ₂ : F, on which silver conductor tracks are applied, via which the pane is heated. In the edge region 10 a, which is composed of the contact surface to the sealant 7, the contact surface to the spacer 3 and a zone of 2 mm beyond him and which is a circumferential approximately 10 mm wide zone, the coating is covered by a glaze, according to described below, deactivated, ie not electrically conductive.

FIG. 2a shows a plan view of a glass pane 1, as used in a multi-pane insulating glass according to the invention of a device with interior temperature reduced relative to the ambient temperature, as the pane spaced closest to the pane. On the side facing the disc space in the insulating glass module, it has a transparent electrically conductive coating 10 made of SnO ₂ : F. In the rotating wheel area 10a, it is deactivated by an applied glaze, ie not electrically conductive.

FIG. 2b shows the individual glass pane 1 in cross section. The coating 10 and the deactivated part in the edge region 10a are shown disproportionately.

Example:

The 10 mm wide peripheral edge area of a 4 mm thick slice of 600 x 800 mm soda lime glass with a one-sided 5 μm thick coating of SnO ₂ : F, which had a sheet resistance of 25 Ω / □, was coated on the Page decorated with a commercially available ceramic paint based on lead-free inorganic glass frit screen-printed. After drying the screen printing ink, the disc was for 6 min. heated to 650 ° C, on the one hand burned the color and on the other hand, the disc was thermally biased. Burning the paint destroys the SnO ₂ : F layer and destroys its electrical conductivity.

With the present invention, a multi-pane insulating glass is provided for devices with an interior temperature lowered relative to the ambient temperature, which reduces fogging by condensation or accelerates the dissolution of the fogging. Compared to the prior art multi-pane insulating glasses, it is easy to manufacture because the flat glass is available in large formats and over the entire surface, i. H. can be applied without applying masks o. Ä., Or because commercially available coated flat glass can be used, since only after the coating is cut. From the now in the production additional process step of deactivating, especially the glazing, the baking process is carried out procedurally simultaneously with the thermal toughening.

Claims (5)

1. Multipane insulating glass for appliances having an inner-chamber temperature which is lower than the ambient temperature, in particular for viewing doors of refrigerators and freezers, which glass comprises at least two panes which are of approximately equal size and are arranged at a distance from one another, the distance being maintained by a spacer which runs continuously around the vicinity of the edge, and one of the two outer panes being provided with a hard, electrically conductive, transparent coating on its side which faces towards the space between the panes, characterized in that the conductive coating, which is applied to the entire surface, has been deactivated in terms of its conductivity in the peripheral area of the pane, containing the contact surface for the spacer, by application and subsequent firing of a glaze.
2. Multipane insulating glass according to Claim 1, characterized in that the coating consists of SnO₂ : F.
3. Multipane insulating glass according to Claim 1 or 2, characterized in that the pane which is closest to the interior chamber of the appliance is provided with the electrically conductive coating.
4. Process for producing coated flat glass materials for the production of multipane insulating glass materials, characterized by the following process steps

   - application of a hard, electrically conductive, transparent coating to the entire surface of a flat glass pane

   - cutting the pane to size

   - deactivation of the coating in terms of its conductivity in the peripheral area of the pane, including the subsequent contact surface for the spacer, by application and subsequent firing of the glaze.
5. Process according to Claim 4, characterized in that the pane is thermally prestressed at the same time as the firing.

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