Patent Description:
Museum display cases have to fulfil many requirements in order to guarantee both the correct protection and preservation of the objects exhibited therein and the best visibility of these objects for the public. Normally, these display cases comprise glass (or in any case transparent) walls assembled together and/or to a frame. Normally, one or more of the walls can be opened to allow access to the interior of the display case.

In many cases a museum display case has to guarantee a total separation between the exterior exhibition environment and the interior exhibition environment; this is the situation when the display case has to accommodate objects that would be damaged by external environmental conditions. In this case, the museum display case is provided to be airtight and to be equipped with a system to control the internal climatic and air quality conditions, in order to have in the interior exhibition environment a predefined controlled atmosphere that is suitable for the objects exhibited. To this end, the various parts of the display case are assembled by bonding with suitable adhesives and sealing gaskets are provided at the openable walls. The interior environment is thus separated from the exterior environment and can be adequately controlled, with more or less complex air conditioning and filtering systems.

The inventor observed that the material of the adhesives, the material of the gaskets and the material of other parts used for the construction of the structure of the display case (e.g. painted parts) are often liable to emit volatile substances harmful to preservation, such as VOCs (volatile organic compounds). In fact, many materials, especially plastics or synthetics, retain more or less large quantities of solvents and volatile chemicals used for production and tend to release them over time; moreover, certain materials gradually transform over time and tend to release volatile substances. If the display case is airtight, the volatile substances emitted towards the interior thereof remain trapped inside the display case and normal filtering systems can hardly remove them. These volatile substances that are present inside the display case were recognised by the inventor as being responsible for possible unexpected deteriorations of the objects exhibited, despite the presence of accurate systems for the control of the internal atmosphere.

<CIT> discloses a museum showcase in which parts susceptible of emitting volatile substances harmful to preservation are shielded, so as not to face the interior exhibition space of the showcase.

For the sake of best preservation, it is therefore appropriate to select the construction materials of the display case also on the basis of the emission power thereof, regardless of the performance of the filtering apparatus. However, making an airtight display case without using materials liable to emit harmful volatile substances has proved to be substantially impossible. Above all, all materials that are sufficiently elastic to ensure the tightness of the openable parts, as well as all adhesive materials required to bond glass and metal materials together, and all paints used on glass or metal parts, have been shown to be liable to emit volatile substances.

The inventor then tried to expose the display case to air for a reasonably long degassing time, so as to allow the natural evacuation of volatile substances before using the display case. However, the results were not satisfactory, as these materials continue to emit volatile substances even after degassing, however long it may be.

The inventor therefore identified the problem of ensuring the correct preservation of the objects exhibited in a museum display case, even if the display case is made using materials that are liable to emit harmful volatile substances.

In accordance with the invention, this problem is solved by a method for improving the behaviour of a museum display case towards objects exhibited therein according to claim <NUM>, by a method for manufacturing a museum display case according to claim <NUM>, as well as by a museum display case according to claim <NUM>.

More particularly, according to the invention, a method for improving the behaviour of a museum display case with respect to objects exhibited therein, wherein the display case has parts facing an interior exhibition space which are made of materials liable to emit harmful volatile substances, comprises the step of subjecting the display case to a heat treatment in which the display case is maintained at a treatment temperature for a treatment time, wherein the treatment temperature is between <NUM>° and <NUM>° and the treatment time is at least <NUM> hours.

Still according to the invention, a method for manufacturing a museum display case comprises the steps of:.

Such heat treatment allows accelerating the release of harmful volatile substances from the materials liable to emit them that have been used for the creation of the display case. After such heat treatment, these materials no longer emit harmful volatile substances in significant quantities; consequently, the display case can be used to exhibit relatively delicate objects.

Preferably, the treatment temperature is between <NUM>° and <NUM>°.

Preferably, the treatment time is at least <NUM> hours.

The invention also relates to a museum display case comprising parts made of materials liable to emit harmful volatile substances, which is characterised in that it has undergone a heat treatment such that said materials have disposed of harmful volatile substances in sufficient quantity so that, under the conditions of use of the display case, said materials no longer emit harmful volatile substances in a quantity which is dangerous for the objects exhibited in the display case.

In one embodiment, the heat treatment is performed by placing the assembled display case in a treatment chamber. This method ensures uniform treatment of all parts of the display case, but it requires a treatment chamber that is adequately larger than the display case, and is therefore rather expensive.

Preferably, according to an alternative embodiment method, the heat treatment is performed by placing heating members in the display case. In this way, the treatment is easier to implement. Its effectiveness is inevitably limited to the parts facing the interior of the display case, but it is precisely in these parts that it is important to dispose of harmful volatile substances: in fact, the emission of volatile substances outside the display case is not a problem, because these substances do not reach the objects exhibited.

Further features and advantages of the invention will best be seen from the following description of a display case according to the invention, shown in the attached <FIG>.

In the drawing, a museum display case <NUM> is schematically shown, which comprises a base <NUM>, surmounted by a box <NUM>. In the box <NUM>, there is the exhibition space of the display case <NUM>, destined to accommodate the objects to be exhibited, while in the base <NUM> there is a technical space for housing the systems for the control of the atmosphere inside the box <NUM> (for example, a simple container with hygroscopic material or a more complex air conditioning and/or filtering system).

The box <NUM> comprises a frame <NUM>, typically made of steel, aluminium or another metal material. The box <NUM> then comprises glass walls mounted on the frame <NUM>, in particular fixed glass walls <NUM> and at least one openable glass wall <NUM>. The fixed glass walls <NUM> are welded to each other, to the frame <NUM> and to the base <NUM> by bonding, using an adhesive substance (not highlighted in the figure). The openable glass wall <NUM> is mounted on the frame <NUM> by means of an openable system, for example a hinge system (not visible in the figure). It should be noted that the frame <NUM> may be eliminated, either completely or in part, leaving the fixed glass walls <NUM> - suitably sized and welded together - with the function of load-bearing structure of the box <NUM>; in this case, the openable glass wall <NUM> is mounted on one or more of the fixed glass walls <NUM>.

The display case <NUM> further comprises sealing gaskets <NUM>, both between the openable glass wall <NUM> and the fixed glass walls <NUM>, or between the openable glass wall <NUM> and the base <NUM>.

In the display case <NUM>, the material of the sealing gaskets <NUM> is liable to emit harmful volatile substances, in particular VOCs. This material is for example a silicone rubber, another elastic material or plastoferrite; the latter material combines excellent elasticity with the possibility of being magnetized, so that the openable glass wall <NUM> can be closed by magnetic attraction.

The adhesive substance with which the fixed glass walls <NUM> are welded and sealed is also a material liable to emit harmful volatile substances.

The display case <NUM> may further comprise other parts (e.g. accessories of various kinds, not shown in the figure, such as partitions, support shelves, lighting fixtures, etc.) made of materials liable to emit harmful volatile substances such as VOCs or other, or painted with paints that can emit such substances.

The display case <NUM> is assembled in a normal way, assembling the various parts as required. Once the assembly has been completed so as to obtain the structure of the display case, without however any hygroscopic material used for moisture control being housed in the base <NUM> of the display case <NUM>, the display case <NUM> is subjected to a heat treatment to dispose of harmful volatile substances from the materials liable to emit them.

For this purpose, the display case <NUM> may be placed in a treatment chamber, where it is maintained at a predefined treatment temperature for a predefined treatment time. It has been verified that if the treatment temperature is between <NUM>° and <NUM>°, the materials liable to emit harmful volatile substances emit these substances in an accelerated manner, so that - if the treatment time is at least <NUM> hours - at the end of the heat treatment these materials have substantially exhausted the ability to emit harmful volatile substances, at least under the normal conditions of use of the display case <NUM>. On the other hand, temperatures in this range are not such as to damage the parts of the display case.

Alternatively and preferably, heating members are placed inside the display case <NUM> so as to maintain the internal parts of the display case <NUM> at the predefined treatment temperature for the predefined treatment time. The heating members may act by convection, heating the air inside the display case <NUM>, and/or by radiation; if the heating members act by radiation (or both by convection and radiation), they are placed so as to direct the radiation towards those parts of the display case <NUM> in which the materials liable to emit VOCs or other harmful substances are located.

This method allows the display case <NUM> to be treated even at the installation site and is therefore preferred when the display case <NUM> (e.g. due to its large size) has to be assembled at the installation site.

During the heat treatment, by whichever method this is performed, a change of air is periodically performed in the interior exhibition space of the display case <NUM>, for a duration of at least <NUM> minutes every hour.

Preferably, the treatment temperature is between <NUM>° and <NUM>°; even more preferably, it is around <NUM>°.

In order to verify the effective elimination or reduction of the harmful volatile substances, the concentration value of the harmful volatile substances in the air inside the display case <NUM> is measured during and at the end of the heat treatment using a per se known equipment.

Once the heat treatment has been completed, any hygroscopic material may be housed in the base <NUM> of the display case <NUM>, in a manner known per se.

The display case <NUM> treated in this way can therefore be used safely, because the materials used therein which are liable to emit harmful volatile substances have exhausted their emission ability, or rather they have reduced it in such a way that they can still emit such substances, but only in a minimal quantity, such that it is not dangerous for the objects exhibited in the display case <NUM>.

Claim 1:
Method for improving the behaviour of a museum display case (<NUM>) with respect to the objects exhibited therein, wherein the display case (<NUM>) has parts (<NUM>) facing an interior exhibition space (<NUM>) which are made of materials liable to emit harmful volatile substances, characterized by comprising the step of subjecting the display case (<NUM>) to a heat treatment in which at least said parts (<NUM>) of the display case (<NUM>) made of materials liable to emit harmful volatile substances are subjected to a treatment temperature for a treatment time, wherein the treatment temperature is between <NUM>° and <NUM>° and the treatment time is at least <NUM> hours.