Process for obtaining insulating glazing and insulating glazing thus obtained

Abstract

The subject of the invention is a process for obtaining insulating glazing (1) comprising a first and a second glass sheet (2, 3) that are kept in a manner spaced apart in parallel with the aid of at least one transparent glass spacer (4) adhesively bonded to the periphery of said glass sheets (2, 3) so as to form a gas-filled interlayer space (5), said process comprising the following steps: - a step of providing said spacer (4), said spacer being substantially parallelepipedal and comprising at least two rough faces (41, 42) opposite one another, and two smooth faces (43, 44) opposite one another, then - a step of assembling said at least one spacer (4) between the glass sheets (2, 3) such that each rough face (41, 42) of said spacer (4) is positioned close to an edge, and against a face (21, 31), referred to as an internal face, of each of said glass sheets (2, 3), the interstitial width between the rough faces (41, 42) of the spacer and the internal faces (21, 31) of the glass sheets (2, 3) being less than 0.01 mm, then - a step of depositing a transparent adhesive at the external joint lines (24, 34) between the rough faces of the spacer and the internal faces of the glass sheets, said adhesive moving by capillary action so as to cover the surface of said rough faces of the spacer, then - at least one step of curing said adhesive.

Description

[0001] The invention relates to the field of insulating glazing intended for incorporation into the openings of enclosures or climate-controlled furniture, particularly refrigerated units. This insulating glazing comprises at least two parallel sheets of glass held apart by means of at least one transparent glass spacer bonded to the periphery of said glass sheets so as to create an intervening space filled with gas.

[0002] The invention will be described more particularly with regard to a refrigerated display case application, but is not limited to it. The glazing of the invention can be used in all building applications, exterior glazing, interior glazing, partitions, etc.

[0003] Among spacers, a distinction is made between those made of synthetic materials, organic materials, and glass. The present invention relates exclusively to glass spacers.

[0004] A climate chamber is more specifically intended to constitute a positive cold cabinet or a negative cold cabinet in which refrigerated or respectively frozen products are displayed, such as food or beverages, or any other products requiring cold storage, for example pharmaceutical products or flowers.

[0005] While frozen products are increasingly sold in refrigerated display cases with transparent insulated glass doors, fresh and ultra-fresh food products are still primarily sold in self-service vertical units within stores. Equipped with a refrigerated air curtain on the front to insulate the food from the store's warm environment and maintain it at the optimal storage temperature, these units are quite efficient in this respect and offer direct access to products without any physical barrier, thus facilitating the purchasing process.

[0006] However, the absence of a physical barrier on these vertical refrigerated display cases results in significant heat exchange between the store environment and the much colder environment generated inside these cases, leading to the following consequences: This heat exchange must be compensated by a greater production of cold in order to guarantee the optimal temperatures for preserving food in the unit, which adversely increases the energy consumption of these units; the atmosphere of the store is considerably cooled locally (cold aisle phenomenon), which leads consumers to limit their passage in these aisles to essential purchases, abandoning impulse purchases.This localized cooling of the affected aisles has become even more pronounced in recent years, as stricter hygiene regulations have led to a further reduction in food storage temperatures. The humid air in the store is drawn out by the cold air curtain at the front of the display case, leading to rapid saturation of the unit's refrigeration exchanger (also called an evaporator), which then ices up, significantly reducing the efficiency of heat exchange. Frequent defrosting of the evaporator, typically twice a day, is therefore necessary, resulting in increased energy consumption and costs.

[0007] Faced with these drawbacks, furniture manufacturers have attempted to provide solutions, notably by optimizing air curtains and heating aisles with radiant or hot air blower units. However, this progress remains limited in terms of customer comfort, and this comes at the expense of energy consumption. Indeed, the heat energy produced by these energy-intensive heating systems is partially retained in the furniture itself, ultimately leading to even greater energy consumption for cooling the units.

[0008] Installing conventional cold storage doors on these open display cases effectively addresses these drawbacks. While these solutions are widely proven in negative temperature refrigeration for frozen products, they have struggled to gain traction in positive temperature refrigeration. These doors are criticized for creating a physical barrier between the consumer and the self-service product, potentially leading to negative sales.

[0009] Furthermore, these operable windows are manufactured using a design similar to that used in buildings: double or triple glazing is framed around its entire perimeter by a frame made of profiles, generally anodized aluminum for aesthetic reasons, resistance to aging, and ease of manufacturing. The frame is usually bonded directly to the perimeter and outer surfaces of the glazing; it contributes to the structural rigidity and conceals the spacers placed around the perimeter of the glazing to separate the panes of glass. However, such a structural frame significantly reduces the visible area through the glazing.

[0010] It was then proposed, in order to improve the visibility through the glazing, to manufacture insulating glazing with transparent spacers at least at the level of their vertical sides, also generating a visual perception of transparent surface continuity over all the refrigerated display cases joined together.

[0011] One known method involves using transparent spacers made of glass and produced by waterjet cutting, ensuring a perfectly parallel bonding surface with the glass panes. The rough surfaces created by the waterjet are positioned at the edge of the glazing to allow the glass panes to be joined by the perfectly smooth surfaces of the spacers. However, this method requires cutting the spacers from glass panes with a thickness precisely matching the spacing between the glass panes in the insulating glazing unit. Furthermore, the waterjet cutting process only allows for the production of spacers with a thickness (the dimension extending in a plane parallel to the overall surfaces of the glass panes when the spacer is installed) of at least 12 mm. Consequently, the desired view and transparency effect are reduced.

[0012] Application WO 2017 / 157636 proposes insulating glass units in which transparent glass spacers are produced by a cutting step, for example by scoring, creating "raw" or rough faces. These spacers are then joined to the glass panes by placing these rough faces against the faces of the glass panes and then applying an adhesive from the outer joint between these two faces. The manufacturing process for insulating glass units is thus simplified, particularly by the possibility of cutting the spacers from glass panes of standard thicknesses. This process also allows for even greater visibility and transparency, since the spacers can be thinner and the faces of the spacer forming the edge of the glass are perfectly smooth, thus providing a perfect transparency effect when the glass is viewed in perspective.The glue used may, in particular, be cross-linkable under ultraviolet radiation.

[0013] However, it has been observed that the resulting glazing can be susceptible to aging, particularly in humid environments. More specifically, cracks can appear in the adhesive over time. In addition to degrading the aesthetic appearance of the glazing, these cracks can lead to a reduction in the airtightness of the opening.

[0014] The invention therefore aims to overcome this drawback by proposing an improved process, making it possible to obtain insulating glazing with better resistance to aging, and consequently better maintenance of the seal in the long term.

[0015] To this end, the invention relates to a method for obtaining insulating glazing according to claim 1.

[0016] The invention also relates to an insulating glazing that can be obtained by this process, said glazing comprising a first and a second sheet of glass held parallel and spaced apart by means of at least one transparent glass spacer glued to the periphery of said sheets of glass so as to provide an intercalary space filled with gas.

[0017] The particular choice, according to the invention, of the width of the gap between the rough faces of the spacer and the inner faces of the glass sheets during the assembly step, makes it possible to avoid the appearance of the cracks described above.

[0018] In the known process described in application WO2017 / 157636, the gap width varies locally because the spacer's flatness is never perfect, and even the occasional use of clamps cannot ensure such a small gap along the entire length of the spacer. Therefore, there are areas where the gap is typically at least 0.1 or 0.2 mm, and can even locally reach 1 mm. It is in these areas that cracks are most likely to form after aging.

[0019] The process according to the invention may also include, prior to the spacer supply step, a spacer cutting step, in particular by scoring or laser cutting, from a sheet of glass, notably obtained by float glass. This cutting step may be carried out in the same workshop or factory as the subsequent steps of the process, or may have been carried out in another workshop or factory, or even by another economic actor. The cutting step is preferably followed by at least one polishing step in order, where necessary, to adjust the roughness of the rough surfaces. The polishing may, for example, be mechanical polishing using abrasive powders.

[0020] The spacer preferably has a generally square or rectangular cross-section. The spacer glass is preferably monolithic. The spacer preferably has two chamfers on one of its smooth faces, particularly the face intended, when the spacer is mounted, to form the edge of the glazing. These chamfers facilitate the application of adhesive from the outer junctions between the rough faces of the spacer and the inner faces of the glass panes.

[0021] The glass spacer preferably has a thickness of 14 mm or less, or 12 mm or less, in particular a thickness between 4 and 14 mm, especially between 6 and 12 mm, or even between 8 and 11 mm. This thickness is reduced compared to that of spacers obtained by waterjet cutting.

[0022] The glass spacer preferably has a width of 10 to 16 mm, especially 12 to 14 mm.

[0023] In this text, "thickness" refers to the dimension extending in a plane parallel to the overall surfaces of the glass sheets when the spacer is mounted; that is, the dimension extending from the edge of the glass sheets towards the interior of the glazing. The thickness therefore corresponds to the distance between the smooth faces of the spacer. This thickness also corresponds to the thickness of the glass sheet from which the spacer was cut.

[0024] As for the "width" of the spacer, it corresponds to the distance between the rough faces of the spacer, therefore to the dimension separating the two sheets of glass in the mounted position of the spacer.

[0025] The roughness Rz of the rough faces of the spacer is preferably in the range of 1 to 10 µm, and more preferably 2 to 9 µm. This roughness corresponds to the roughness Rz as defined in ISO 4287:1997. For roughness evaluation, the limiting wavelength (also called cut-off) λc is preferably 0.8 mm. Such a roughness is favorable for achieving the gap widths as claimed.

[0026] The smooth faces of the spacer preferably correspond to faces of float-formed glass sheets. They therefore have extremely low roughness, with the Rz roughness generally being less than 0.2 µm. In all cases, the roughness of the smooth faces is lower than the roughness of the rough faces.

[0027] The glass panes are preferably made of tempered glass. The thickness of each pane is between 2 and 5 mm, and preferably 3 to 4 mm in order to minimize the overall weight of the glazing and optimize light transmission.

[0028] The glass sheets are preferably obtained by flotation. They are preferably made of clear or extra-clear glass, always with the aim of optimizing light transmission.

[0029] The glass panes are held apart by spacers to create an intervening space filled with gas, also called a "gas gap". The gas gap is preferably at least 4 mm thick and is adapted according to the desired U-value performance, but is normally no more than 16 mm, or even 20 mm.

[0030] The gas gap is advantageously made of air or, preferably, to enhance the glazing's insulation, of a rare gas chosen from argon, krypton, xenon, or a mixture of these gases, with a fill level of at least 85%. For an even better U-value, a fill level of at least 92% krypton or xenon is preferred.

[0031] In the assembly stage, the transparent glass spacer(s) is placed between the two sheets of glass.

[0032] The assembly step is preferably preceded by the application of an adhesion primer to the rough surface of the spacers and / or to the inner surface of the glass sheets intended to come into contact with the spacers. The application of the adhesion primer may itself include a preliminary step of depositing silica or silicates by flame pyrolysis. The flame also allows for the removal of any residual traces of water or solvent.

[0033] The assembly is preferably done horizontally, by placing the spacer(s) on the first sheet of glass, then placing the second sheet of glass on top of the spacer(s). The assembly of glass sheets and spacers obtained after the assembly step will be called the "assembly".

[0034] The transparent glass spacer(s) is generally placed along an entire edge, as any butting of spacers is detrimental to the sealing of the glazing and requires the addition of an unsightly sealant.

[0035] Generally, two transparent glass spacers are placed near opposite edges of the glass panes. When the glass panes are rectangular, these opposite edges are preferably the long edges, which generally correspond, in the installed position, to the vertical sections of the glazing. In this configuration, non-transparent spacers and sealing elements, such as metallic, polymeric, or composite spacers and opaque sealants, are also placed along the short edges of the glass panes, which generally correspond, in the installed position, to the horizontal, top and bottom edges of the glazing. To ensure a good seal, a sealant is preferably applied to the corners of the assembly, and therefore of the glazing, at the connection between the non-transparent spacer and the glass spacer.The term "periphery" therefore generally does not mean the entire periphery of the glazing, but usually at least one edge.

[0036] Clamping devices, such as clamps, are preferably positioned at different locations along the edge of the glazing, so as to hold the assembly in position by exerting pressure on the glass sheets.

[0037] At the end of the assembly stage, and even at the beginning of the glue application stage, the interstitial width between the rough faces of the spacer and the inner faces of the glass sheets must be at most 0.01 mm, over the entire length of the spacer, therefore generally over the entire length of the edge of the glass sheet near which the spacer is positioned.

[0038] Whether the gap width is less than 0.01 mm is preferably verified immediately after assembly and before the adhesive is applied, using calibrated shims or thickness gauges, typically made of steel. To do this, an operator attempts to insert the shim into the gap separating the rough faces of the spacer from the inner faces of the glass sheets, without forcing it, across the entire thickness of the spacer, starting from the outer joint line between the rough faces of the spacer and the inner faces of the glass sheets. This operation is repeated along the entire edge length of the glass sheets. The gap width is considered less than 0.01 mm when it is not possible to insert a shim with a thickness of 0.01 mm.If there are areas on the edge of the glass sheets into which a 0.01 mm thick shim can be inserted, the gap width is then 0.01 mm or more, and clamping means can be added or moved in these areas to locally reduce this gap width.

[0039] Surprisingly, even such narrow gaps allow for sufficient bonding with good tensile strength. Thanks to the roughness of the rough surfaces, the adhesive can be drawn in by capillary action and spread throughout the entire gap, even if it is very small.

[0040] The adhesive is applied to the external joint lines between the rough faces of the spacer and the internal faces of the glass panes. The "external joint line" refers to the joint line located on the outside of the glazing.

[0041] The adhesive can, for example, be applied using a syringe moved along the edge. The adhesive then spreads by capillary action, ensuring even distribution within the gap and a uniform bond.

[0042] During the adhesive application stage, the adhesive preferably has a viscosity between 300 and 900 mPa.s. This optimizes capillary movement.

[0043] To ensure a clear view, the difference between the refractive index of the adhesive, after curing, and the refractive index of the glass used for the spacers and glass sheets is preferably no more than 0.3, specifically no more than 0.2, and even no more than 0.1. This eliminates the visual impact due to the roughness of the spacer's rough faces. Typically, the spacers and glass sheets will be made of soda-lime glass, which has a visible refractive index of around 1.5. The visible refractive index (for example, at 550 nm) of the adhesive after curing is preferably between 1.4 and 1.6.

[0044] The adhesive is preferably cross-linkable under ultraviolet radiation. The ultraviolet-crosslinkable adhesive preferably comprises at least one oligomer, at least one monomer (also called a diluent) and at least one photoinitiator.

[0045] The oligomer preferably consists of an oligomeric chain terminated at each end by a reactive function capable of polymerization. The oligomer preferably comprises an acrylate function at each end of an oligomeric chain selected from polyurethane, polyester, polyether, epoxy, and polysiloxane chains.

[0046] The monomer preferably possesses one or more reactive functional groups and, after polymerization, is incorporated into the polymer network. The monomer preferably includes at least one acrylate group. The presence of the monomer reduces the viscosity of the adhesive, as the oligomer itself is too viscous.

[0047] A photoinitiator is a chemical compound whose photolysis releases species reactive to the functional group of the monomer. The photoinitiator is preferably of the radical type. The photoinitiator is preferably an aromatic ketone.

[0048] When the glue is crosslinkable under ultraviolet radiation, the curing step is carried out by exposure to ultraviolet radiation.

[0049] The exposure is preferably carried out from only one side of the assembly, in order to crosslink the adhesive located on both sides of the spacer in a single step. A radiation source is then placed on only one side of the assembly, preferably underneath the assembly.

[0050] Alternatively, the exposure can be carried out on each side of the assembly. Two radiation sources are then placed on either side of the assembly. In this case, the exposure can be carried out simultaneously or not.

[0051] The radiation source(s) preferably extend over the entire length of the spacer to be glued.

[0052] Preferably, when the assembly includes two transparent glass spacers near opposite edges of the glass sheets, the exposure step is carried out using two radiation sources, each positioned on one side of the assembly opposite one of the spacers. This allows the adhesive to be cured for the entire assembly in a single step.

[0053] It has been observed that curing conditions, particularly the type and power of the lamp used, also impact the development of cracks during aging. The amount of energy received, which depends on the wavelength, lamp power, distance between the lamp and the assembly, and exposure time, is a particularly important parameter, as it influences the curing rate of the adhesive and therefore the quality of the curing. The curing rate increases with the amount of energy received over a given period. When the curing rate is too low, unwanted reactions, for example with the adhesive's environment (water, oxygen, volatile compounds), compete with the adhesive's curing reaction, thus hindering proper hardening.An excessively high curing rate leads to stress buildup in the adhesive and may even result in its initial degradation. The adhesive's resistance to aging depends on how the ultraviolet radiation dose was delivered. For a given dose, the choice of exposure time and intensity has been shown to have a significant impact.

[0054] Ultraviolet radiation can be of the UV-A type (wavelengths from 315 to 400 nm) and / or UV-B type (wavelengths from 280 to 315 nm).

[0055] Ultraviolet radiation is emitted from at least one source. Preferably, this ultraviolet radiation is emitted from light-emitting diodes (UV LEDs). Ideally, the emission spectrum is such that at least 95% of the power is emitted at wavelengths between 360 and 390 nm. Using this type of device reduces adhesive cracking compared to UV discharge lamps, which have a much broader and less intense emission spectrum, requiring longer exposure times.

[0056] It was shown that the intensity emitted by the radiation source, the duration of exposure and the distance between the assembly and the radiation source influenced the appearance of cracks after aging.

[0057] The intensity of the ultraviolet radiation (emitted by the source) is preferably in the range of 10 to 200 mW / cm², in particular 20 to 150 mW / cm², or even 40 to 100 mW / cm². The duration of exposure to ultraviolet radiation is preferably in the range of 1 to 1000 seconds, in particular 10 to 500 seconds, or even 100 to 300 seconds. The distance between the radiation source and the assembly is preferably in the range of 0.5 to 5 cm, in particular 0.6 to 3 cm, or 0.7 to 2 cm.

[0058] The glazing can advantageously be provided on at least one of the glass panes with one or more low-emissivity coating(s) and / or an anti-fog or anti-frost layer, thus avoiding the use of conventional heating methods, which contributes to energy savings.

[0059] The glazing consists of two panes of glass. It can also consist of three, in which case it is triple glazing. In this case, the edge of the glazing includes two spacers, arranged between the three panes of glass.

[0060] The invention also relates to a climate-controlled piece of furniture, of the refrigerated type, in particular with positive cold, comprising at least one insulating glazing according to the invention, the glazing being in particular integrated into an opening.

[0061] The furniture may include a plurality of glass panes placed vertically next to each other, the transparent spacer(s) generally being arranged vertically in the mounted position of the glass pane(s).

[0062] The unit, for example, is a refrigerated display case designed to be installed along a store aisle. It can be constructed with a row of doors joined laterally to each other vertically along their edges.

[0063] In the case of a refrigerated display case / furniture, where airtightness is less critical than for a refrigerated display case / furniture, the opening according to the invention, incorporating the insulating glazing of the invention, does not need to include vertical frame members with thick gaskets at the junction of two joined openings / glazing units. The glazing obtained according to the invention thus provides, through the transparency of its vertical edges, a continuous transparent surface when the glazing units are joined edge-to-edge.

[0064] Each insulating glazing unit comprises at least two panes of glass held parallel and spaced apart by spacers which are preferably transparent at the level of the opposite vertical parts in the mounted position of the glazing.

[0065] The glass fronts, and therefore the furniture itself, are thus free of any structural frame and present a smooth, glass-wall appearance. This maximizes the viewing area.

[0066] The transparent spacer(s) are preferably positioned vertically in the mounted position of the glazing unit(s). They are therefore generally placed along the long edges of rectangular glass sheets.

[0067] Transparent spacers can also be placed horizontally in the mounted position of the glazing unit(s). However, it is preferable to use non-transparent spacers and sealants, particularly those typically used in the manufacture of insulating glass units, which are therefore less expensive. The horizontal sections at the top and bottom of the insulating glass unit are located in areas where they do not obstruct the view of the displayed products. These can include metallic spacers, for example, made of aluminum, or polymeric or composite spacers, and non-transparent sealants. A strip of enamel, for example black, can be applied, notably by screen printing, to at least one of the glass panes opposite the non-transparent spacers and sealants to conceal them.

[0068] Preferably, the glazing comprises two transparent glass spacers bonded along the entire length of the long edges of the glass panes, and two non-transparent spacers, for example metallic, polymeric, or composite, bonded along the entire length of the short edges of the glass panes. To prevent thermal bridging and thus improve the thermal insulation properties of the glazing, the non-transparent spacers are preferably polymeric or composite (reinforced polymer). For example, they could be spacers made of a styrene-acrylonitrile copolymer reinforced with glass fibers.

[0069] The glazing may also include, along the long edges, a transparent profile, for example polymeric, particularly polycarbonate. This profile can be bonded to the smooth faces of the spacers located on the outside of the glazing as well as to the edges of the glass panes.

[0070] The glazing obtained according to the invention preferably exhibits at least one of the following performance characteristics after aging: a moisture penetration index measured under the conditions of standard EN 1279-6 of no more than 5%, a moisture penetration index measured under the conditions of standard EN 1279-2 of no more than 15%, a gas leakage rate measured under the conditions of standard EN 1279-3 of no more than 1.0% per year, in particular no more than 0.5% per year.

[0071] The examples and figure that follow illustrate the invention in a non-limiting manner.

[0072] [ Fig 1 ] illustrates a partial cross-sectional view of an assembly of glass sheets and transparent spacer intended, at the end of the assembly step.

[0073] Apart from the glue, the various constituents of the final glazing are shown in this figure, which can therefore also represent a partial cross-section of glazing obtained according to the invention.

[0074] The glazing 1 is obtained by assembling a first and second sheet of glass 2 and 3, held parallel and spaced apart using a transparent glass spacer 4 so as to leave an intercalary space 5, which will be filled with gas.

[0075] The spacer 4 is substantially parallelepiped, with an overall rectangular cross-section, if we neglect the presence of the chamfers 45 and 46. The spacer 4 comprises two rough faces 41 and 42 opposed to each other and two smooth faces 43 and 44 also opposed to each other.

[0076] The spacer 4 was obtained by cutting from a sheet of float glass, the rough faces 41 and 42 corresponding to the cut faces (possibly after further polishing) and the smooth faces 43 and 44 to the original faces of the glass sheet.

[0077] The assembly is carried out so that each rough face, 41 and 42 respectively, is positioned against an inner face, 21 and 31 respectively, of the glass sheets 2 and 3, near an edge. The smooth face 43 is therefore located on the outer edge of the glazing, and the smooth face 44 is turned towards the intervening space.

[0078] During the assembly stage, clamps (not shown) are preferably positioned in certain areas of the assembly edge to exert pressure on the glass sheets. The assembly is preferably formed horizontally, as shown in the figure. The gap width is thus influenced by the roughness Rz of the rough surfaces and by the vertical pressure due to gravity and the clamping force exerted by the clamps.

[0079] In figure 1 , glass sheets 2 and 3 are also chamfered.

[0080] The assembly forms external joining lines 24 and 34 between the rough faces 41 and 44 and the internal faces 21 and 31 of the glass sheets. The adhesive is applied along these joining lines, for example, using a syringe. The chamfers facilitate this application.

[0081] An assembly such as the one shown in figure 1 was formed from square sheets of glass 10 cm on each side and transparent glass spacers 10 cm long.

[0082] The spacers were rectangular in section (10 mm thick and 13 mm wide) with a chamfer.

[0083] Before assembly, the rough faces of the spacers and the area of ​​the inner faces of the glass sheets intended to come into contact with the spacers were coated with an adhesion primer. The primer application was carried out in two stages: first, a silica deposit by pyrolysis using a torch, then a deposit of Pyrosil® primer, marketed by Bohle.

[0084] Clamps were placed to hold the assembly in place during the glue application and curing stages.

[0085] For the comparative examples, the gap width was determined by the insertion of calibrated thickness gauges at the ends of the assembly. For the examples according to the invention, no thickness gauge was placed in the assembly, but a check using a calibrated 0.01 mm thickness gauge confirmed that the gap width was less than 0.01 mm. Along the length of the spacer, it was impossible to insert the gauge through its entire thickness without forcing it.

[0086] Two types of spacers were used. Spacer 1 has a roughness Rz of 5 to 6 µm, spacer 2 has a roughness Rz of approximately 4 µm.

[0087] The adhesive (Verifix LV 740 marketed by the company Bohle) was then applied using a syringe at the external junction lines between the rough faces of the spacer and the internal faces of the glass sheets.

[0088] The assembly was then subjected, in the bonding area, to exposure to ultraviolet radiation using two types of radiation sources: a Neon type discharge lamp, having an emission spectrum with a broad band from 320 to 400 nm and centered on the wavelength of 360 nm, or an LED lamp having a narrow emission spectrum between 360 and 390 nm.

[0089] The lamps were located 1 cm from the assembly.

[0090] The resulting glazing was subjected to accelerated aging in a humid environment, at a temperature of 58°C for a relative humidity greater than 95%.

[0091] The table below shows, for each of the tests, the type of spacer (1 or 2), the interstitial width (noted i and expressed in mm), the nature of the source, the intensity of the source (noted I, in mW / cm 2< ), the duration of exposure (noted d and expressed in seconds), as well as the results of the aging test.

[0092] These results consist of an initiation time (denoted t and expressed in hours) and a qualitative score (denoted F, unitless). The F score is given after visual examination of the bonded area. A score of 5 or less indicates no cracking or very little cracking. The higher the score, the more significant the cracking in the bonded area. The initiation time corresponds to the aging period after which the samples obtain a score of 5. [Table 1] Esp. i (mm) Source I (mW / cm 2< ) d (s) t (h) F C1 1 0,03 Néon 14 300 74 7 C2 1 0,09 Néon 14 300 40 12 C3 1 0,15 Néon 14 300 48 13 C4 1 0,18 Néon 14 300 48 10 C5 1 0,18 LED 75 180 72 12 1 1 <0,01 Néon 14 300 >408 1 2 1 <0,01 LED 75 180 408 4 3 2 <0,01 LED 75 180 >408 0

[0093] Comparison between examples according to the invention 1 to 3 and comparative examples C1 to C5 shows that choosing an interstitial width of less than 0.01 mm makes it possible to largely avoid the appearance of cracks after wet aging.

[0094] Other aging tests were also carried out on glazing obtained or not according to the invention.

[0095] Moisture penetration tests after a short aging cycle were carried out under the conditions of EN 1279-6, and in the case of an implementation of the invention conforming to that of Example 3, the moisture penetration index I was less than 5%. Conversely, in an implementation in which the pore width was not less than 0.01 mm, the index I was generally greater than 10%, or even 20%.

[0096] Moisture penetration tests after a long aging cycle (EN 1279-2 standard) were also carried out. In the case of a product manufactured according to the invention (example 3), the moisture penetration index was at most 15%.

[0097] Finally, gas leakage measurement tests after aging were carried out in accordance with EN 1279-3. In the case of manufacturing according to the invention (example 3), the gas leakage rate L i was at most 0.4% per year.

Claims

1. A process for obtaining an insulating glazing (1) comprising first and second glass sheets (2, 3) that are held parallelly spaced apart with the aid of at least one transparent glass spacer (4) adhesively bonded to the periphery of said glass sheets (2, 3) so as to make a gas-filled interlayer space (5), said process comprising the following steps: - a step of providing said spacer (4), said spacer being substantially parallelepipedal and comprising at least two rough faces (41, 42) opposite one another, and two smooth faces (43, 44) opposite one another, then - a step of assembling said at least one spacer (4) between the glass sheets (2, 3), so that each rough face (41, 42) of said spacer (4) is positioned close to an edge, and against a face (21, 31), referred to as an inner face, of each of said glass sheets (2, 3), the interstitial width between the rough faces (41, 42) of the spacer and the inner faces (21, 31) of the glass sheets (2, 3) being less than 0.01 mm, then - a step of depositing, at the external joint lines (24, 34) between the rough faces of the spacer and the inner faces of the glass sheets, a transparent adhesive, said adhesive moving by capillary action so as to cover the surface of said rough faces of the spacer, then - at least one step of curing said adhesive; at the end of the assembling step, the interstitial width between the rough faces of the spacer and the inner faces of the glass sheets should be at most 0.01 mm, over the entire length of the spacer, therefore generally over the entire length of the edge of the glass sheet in the vicinity of which the spacer is placed.

2. The process as claimed in claim 1, wherein the Rz roughness, within the meaning of the ISO 4287:1997 standard, of the rough faces (41, 42) of the spacer (4) is within a range of from 1 to 10 µm, in particular from 2 to 9 µm.

3. The process as claimed in either of the preceding claims, wherein the spacer (4) preferably has two chamfers (45, 46) on the smooth face (43) intended, in the mounted position of the spacer (4), to form the edge face of the glazing (1).

4. The process as claimed in one of the preceding claims, wherein, during the step of depositing the adhesive, the latter has a viscosity of between 300 and 900 mPa.s.

5. The process as claimed in one of the preceding claims, wherein the adhesive is UV crosslinkable and the curing step is carried out by exposure to ultraviolet radiation.

6. The process as claimed in the preceding claim, wherein the exposure to ultraviolet radiation is carried out from a single side of the assembly.

7. The process as claimed in either of claims 5 and 6, wherein the ultraviolet radiation is derived from light-emitting diodes.

8. The process as claimed in one of claims 5 to 7, wherein the intensity of the ultraviolet radiation emitted by the source is within a range of from 10 to 200 mW / cm2, in particular from 20 to 150 mW / cm2.

9. The process as claimed in one of claims 5 to 8, wherein the duration of exposure to the ultraviolet radiation is within a range of from 1 to 1000 seconds, in particular from 10 to 500 seconds.

10. The process as claimed in one of the preceding claims, wherein the difference between the refractive index of the adhesive, after crosslinking, and the refractive index of the glass used for the spacers (4) and the glass sheets (2, 3), is preferably at most 0.3, in particular at most 0.1.

11. The process as claimed in one of the preceding claims, further comprising, prior to the step of providing the spacer (4), a step of cutting the spacer (4), in particular by scoring-breakage or laser cutting, starting from a glass sheet, in particular obtained by the float process.

12. An insulating glazing (1) capable of being obtained by the process as claimed in one of the preceding claims, said glazing comprising first and second glass sheets (2, 3) that are held parallelly spaced apart with the aid of at least one transparent glass spacer (4) adhesively bonded at the periphery of said glass sheets (2, 3) so as to make a gas-filled interlayer space (5).

13. The insulating glazing (1) as claimed in the preceding claim, which comprises two transparent glass spacers (4) adhesively bonded to the entire length of the long edges of the glass sheets (2, 3), and to non-transparent spacers adhesively bonded to the entire length of the short edges of the glass sheets (2, 3).

14. The insulating glazing (1) as claimed in either of claims 12 and 13, which has at least one of the following performances, after aging: - a moisture penetration index measured under the conditions of the EN 1279-6 standard of at most 5%, - a moisture penetration index measured under the conditions of the EN 1279-2 standard of at most 15%, - a gas leakage rate measured under the conditions of the EN 1279-3 standard of at most 1.0% per year, in particular of at most 0.5% per year.

15. A climate-controlled unit, in particular a refrigerated chiller unit, comprising at least one insulating glazing (1) as claimed in one of claims 12 to 14, in particular integrated into a door.

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