MXPA98009560A - Process to obtain decorations on glass packaging objects and decorated objects obtained by this proc - Google Patents

Abstract

The present invention relates to a process for the deposition, on the surface of objects made of silicon-sodium-calcium glass, which is intended to be for packaging liquid, solid or paste-like food products, such as alcohols, for example, bottles or flasks, of a decoration consisting of a virtually indelible coating, continuous or otherwise, of an enamel composition that does not contain heavy metals such as lead, producing after baking, a matte or satin visual effect and / or colored, the process consists, in a continuous treatment machine, which is fully automated, from the removal of each unfinished object from a pre-existing warehouse or inventory, to the placement of the object, decorated, in a warehouse or inventory that is being formed for the removal, on effecting the deposition, of the enamel object in the form of a pulvurulent, dry frit, by a process of the ele crostatic, but at room temperature, and then heat the enamel on the object to cause the cooking or baking of the enamel, but not cover the objec

Description

PROCESS TO OBTAIN DECORATIONS ON GLASS PACKAGING OBJECTS AND DECORATED OBJECTS OBTAINED BY THIS PROCESS DESCRIPTION OF THE INVENTION The present invention relates to processes for creating satin or matte designs on the surface of glass objects, such as bottles, flasks and the like. It also relates in a particular way to a process for obtaining visual effects of this type on objects made of silicon-sodium-calcium glasses known in this technique as "glass in packaging" and which is intended in particular to contain liquid food products such as alcohols, for example cognac, vodka, etc. Since these are considered mass consumption products, such process must be carried out continuously and at high speed, which implies their complete mechanization from the moment when an unfinished object is removed from a warehouse or inventory, for example on a supply platform. , until that in which the finished product is deposited in a warehouse or inventory of the training process, for example a pallet to be transported to a user. The only techniques used so far for this category of glasses depend on the removal of material, either by attack with hydrofluoric acids and / or REF: 28894 hydrochloric, or by mechanical attack by grinding, which with contaminating and / or hazardous techniques . The process of the present one tries to replace this technology avoiding all its disadvantages. This is essentially based on the application to this field of the process technique, in other well-known aspects, of electrostatic spraying, but adapted to the restrictions and objectives of the new field in question. It should be noted that the use of electrostatic deposition of a powdery enamel to create a decorative visual effect on a bottle was suggested in French patent application No. 2 229 659. However, the restrictions linked to this application of electrostatic deposition ( the use of an enamel composition containing a relatively high proportion of lead, the use of the process at high temperature) has not led to an effective use of such a process. The present invention allows, inter alia, the elimination of all these restrictions and at the same time proposes a suitable process that can be used in an economically advantageous manner over the category of objects mentioned above. Up to this point, the invention relates to a process for the deposition, on the surfaces of objects made of silicon-sodium-calcium glass which is intended to be used to pack liquids, solids or similar to pastes, such as bottles or jars, of a decoration formed of a virtually indelible coating, continuous or otherwise, of an enamel composition that does not contain heavy metals such as lead, which produces, after baking, a matte or satin and / or colored visual effect, such process consists, in a machine of continuous treatment, which is completely automated, from the removal of the unfinished object of a warehouse or pre-existing inventory for the placement of the same object, decorated, on a material that is being formed to remove, when making the deposition, from the surface of the object in enamel in the form of a dry frit in a powdery state by means of an electrostatic process at temperatur to environment, and then bake the glaze thus deposited on such an object. "Container glasses" are well known for the packaging of mass consumer goods. These are silicon-sodium-calcium glasses, the compositions of which are generally within the following framework: Si02: 70 to 74% Na20 and K20: 13 to 16% CaO and MgO: 10 to 13% BaO: 6 to 6.5% A1203: 1.5 to 2.5% A first novel feature of the invention therefore resides in this novel application of the technology of electrostatic deposition of enamels to satin packaging glasses. The enamel compositions used in the present process must satisfy several criteria. The first criterion is the absence of heavy metals, particularly lead, of those compositions. In fact, since the objects to be treated are to contain food products, and in particular alcohols, it is important that these products do not carry the risk of putting them in contact with the heavy metals, which are known to be very toxic. On the other hand, the absence of heavy metals tends to lower the density of the compositions, which facilitates their use, due in particular to their fluidity in the flexible conduits in which they move. In addition, too dense compositions, or even in a dry state, tend to agglomerate and accumulate in blocks at the bottom of the electrostatic treatment chamber. The use of the enamel compositions without heavy metals therefore represents a second important feature of the use.

In addition, to facilitate the handling of these compositions it is desirable to remove the difficulty that results from the irregularity and roughness of the particles. For this purpose, these particles are preferably individually coated in a lubricant of the silicone type, which makes them regular, rounded and lubricated. The granular dimension of these enamel compositions can advantageously be of the order of 5 microns on average. Finally, the density of these compositions is generally of the order of 1.6 to 1.7. The powdery compositions employed by the present invention therefore consist of an enamel frit without any heavy metal, with particle sizes of the order of about 5 microns, coated in a silicone film, and of a density of about 1.6-1.7, compositions which had never been proposed. Such a composition, which is useful in the invention, is designated by the name "VN 9668 PU" by the company CERDEC, in Limoges, France. The technique of electrostatic spraying of powdery products is another aspect that is well known in principle, as mentioned above. However within the framework of the present invention, has been subjected to a number of adaptations which are contrary to current ideas, in these adaptations other essential features of the invention are presented. First, considering that the powdery enamel composition is introduced into an electrostatic field created between a cathode and an anode, a first embodiment of the invention consists of using the nozzle through which the composition is projected by an air current. compressed as the cathode, while the anode is placed inside the object, for example towards the bottom of the bottle. However, although it could be considered until now that the heating of the receiving bottle could facilitate the work of the process, it has been found in the present case that on the contrary this heating leads to a repulsive effect detrimental to the efficiency of the process. A third characteristic of the present process therefore lies in the fact that, contrary to the known processes, the electrostatic deposition of the powdery enamel composition is carried out at room temperature. "Ambient temperature" here means the temperature between about 10 and 28 ° C, it should be understood that raising this temperature causes a decrease in efficiency, so that it seems desirable to work at the lowest possible "ambient" temperature.

"Efficiency" here means the speed at which the bottles must move along to retain a given amount of enamel deposited electrostatically. This means that, when the temperature at which the electrostatic deposition takes place increases, the amount of enamel actually retained by each bottle decreases, so that, in order for the total amount deposited on a bottle to remain the same, the bottle has that remain exposed to the deposition process for a prolonged period, which in turn implies decreasing the speed at which the bottles move along, which therefore corresponds to a corresponding decrease in the overall efficiency of the apparatus. Second, it has been found, in accordance with yet another characteristic of the invention, that the pretreatment, in another of the known aspects for other purposes, of the bottle, allows the introduction of the anode into the bottle to be omitted. It should be recalled, in effect, that, take into account the vulnerability of the so-called "fragile" glasses, and in particular the packaging glasses in relation to physical and mechanical factors (risk of scratching) and chemicals (attack by atmospheric agents), ' it is known how to subject these glasses to superficial treatments consisting on the one hand of depositing on the object at high temperature (650 ° C) a tin tetrachloride (SnCl4) or titanium oxide (Ti02) film, and on the other hand deposit on the object at low temperature (120 - 180 ° C) a film of a salt of oleic acid or low pressure polyethylene (low density). However, the presence of these films on the object when the latter is subjected to an electrostatic enamel deposition results in the creation in this deposition, of visual irregularities, such as mottled and scratched. To avoid these irregularities, an additional coating of a composition based on polyethylene waxes can be used before the electrostatic deposition. The application of such additional coating to the objects that are subjected to the aforementioned surface treatments falls within the scope of the present invention. However, such additional coating is accompanied by additional effects which were not anticipated and which lead to additional essential features of the present invention. In fact, it has been found that such additional layer also gives the glass surface an electrical charge, in such a way that it becomes possible to conduct the electrostatic deposition process while completely eliminating the electrode that was customary placed inside the bottle.

Of course, in this regard, the additional layer can also be applied to objects that have not received the aforementioned surface treatments, so that, according to a preferred embodiment, the invention consists of effecting the electrostatic deposition of the enamel composition powder in an apparatus that includes only one cathode formed by the projection nozzle, the anode being formed by the object itself, which has received an additional layer of composition based on polyethylene waxes. The application of this layer to the bottle and the elimination of the anode in the electrical assembly allowing the electrostatic deposition of the enamel composition to constitute therefore a fourth feature of the invention. Furthermore, it has surprisingly been found that such an additional layer causes an increase in the overall efficiency of the apparatus in the direction specified above; This increase in efficiency can reach 20% and more. Such additional coating compositions are known and commercially available but for other purposes. An example of the subject is manufactured and marketed under the brand "TEGOGLAS 702" by the company Th. Goldschmidt AG in ESSEN in Germany, for limited applications to the protection of glass against scratches and breakage. The total of the powder enamel composition is not deposited and / or retained on the surface of the object, the rest is recovered in the filtration system of the apparatus for recycling. After this deposition, the objects covered with the composition are subjected to heating to bake the enamel in itself, without of course melting the glass itself. Up to this point, the temperature of this baking is of the order of 600 - 650 ° C. In this regard, the process according to the invention can, of course, be combined with the known processes for decorating glass objects by means of other thermofusible enamels to obtain various signs, marks and decorations. In this regard, it should be noted that the terms used in the present description, "continuous or otherwise" and "matte or satin and / or colored visual effect" encompass all visual effects for decorative or informative purposes, primarily both to obtain example, white, black or different colored satiny bottles and also bottles having deposits that form a graph, the brand and / or any other information related to the product contained in those bottles, or a plurality of those effects simultaneously. The entire process according to the invention is also essentially susceptible to mechanization, that is to say in continuous and automatic, allowing, with a conveyor to transport the bottles at an average speed of 25cm / second, the treatment of up to 3600 bottles per hour, in a machine or apparatus that includes means for depositing and arranging the bottles without any contact in the baking tunnel, to allow them the necessary and sufficient drying time in the tunnel without interrupting therefore the supply and continuous removal of the bottles. These means are known and consist of transport drive toothed wheels mounted retractably in a synchronized manner with the duration of the passage in the tunnel. Such a machine is known and built for example by the company ELMETHERM, of Limoges, France. Using this machine or apparatus, the objective of the present invention, which is related to the implementation of the process thus defined with its characteristics, according to a fully automated and continuous process, is also achieved. This process can be described roughly by means of an example: the bottles are taken to the machine in an unfinished state on a pallet and are deposited on a conveyor that moves at 25cm / second by means of a semiautomatic desentaimator which passes through a first cabinet in which an additional coating is applied, as defined above. From there, a screw deposits the bottles on a loading drum which holds the bottles to a top conveyor equipped with caps. The bottles are thus carried to a second cabinet in which they are subjected to the electrostatic deposition of the enamel composition as defined above. The composition is designed by an arrangement of pneumatic guns, under a dust extraction pressure of 2.5 bars, and with a vehicle air flow velocity of 5 m3 / hour. The distance between a barrel and the bottle is 240 mm, and the potential difference between the barrel - that is to say the cathode - and the bottle that forms the anode, is 100 Kv. The bottle leaves this cabin with a coating of approximately 2.5 g of the enamel composition and is taken to a baking oven on the conveyor belt from which it is deposited by an arm, in groups of 25 bottles, without the total cycle being stop, by means of decoupling that results in temporary retraction of the drive sprockets. When the baking or cooking is finished, the bottles are taken again by the conveyor which takes them to the exit of the machine, to be transported to the user. To recycle the amount of enamel composition that has not been set by the bottles, this composition is collected by a suction filter that works at 7 mVhour which returns this to the pumps that feed the cannons. Of course, the use of any other machine or apparatus that allows the continuous and automated implementation of the present process falls within the scope of the present invention.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention. Having described the invention as above, property is claimed as contained in the following:

Claims (11)

1. A process for the deposition, on the surface of objects made of silicon-sodium-calcium glass which is intended to be for packaging liquid, solid or paste-like food products, such as alcohols, for example, bottles or jars, of a decoration which consists of a virtually indelible coating, continuous or otherwise, of an enamel composition that does not contain heavy metals such as lead, producing after baking, a matte or satin and / or colored visual effect, the process is characterized in that consists, in a continuous treatment machine, which is completely automated, from the removal of each unfinished object from a warehouse or pre-existing inventory, to the placement of the object, decorated, in a warehouse or inventory that is being formed for the removal , when making the deposition, on the enamel object in the form of a pulvurulenta, dry frit, by a process of the electrostatic type, but at room temperature, and then heat the enamel on the object to cause the cooking or baking of the enamel, but not cover the object.

The process according to claim 1, characterized in that the enamel particles in the frit have a dimension of approximately 5 microns and the density is approximately 1.6 - 1.7.

3. The process according to claims 1 and 2, characterized in that the enamel particles in the frit are individually coated with silicone.

The process according to claims 1 to 3, characterized in that during the passage of the object in the apparatus for the electrostatic deposition of the powder enamel composition, the composition is pneumatically projected towards the electrostatic field by a nozzle forming one of the electrodes created by such a field, namely the cathode, the other electrode, namely the anode, is introduced during the passage, into the object, and then removed from the object after the passage.

The process according to claims 1 to 3, characterized in that before its passage to the apparatus for the electrostatic deposition of the enamel composition, the object has been subjected to an additional surface treatment comprising the coating with a film of a composition that creates a layer of surface electrostatic charges and, during the passage of the object in the apparatus, the composition is projected towards the electrostatic field by a nozzle that creates one of the electrodes that create such a field, namely the cathode, while The second electrode, namely the anode, is formed by the object itself, which contains the electrostatic surface layer.

The process according to claim 5, characterized in that the composition of the additional film comprises a polyethylene wax.

The process according to any of claims 1 to 6, characterized in that the container glass composition is: Si02: 70 to 74% Na20 and K20: 13 to 16% CaO and MgO: 10 to 13% BaO: 6 to 6.5% A1203: 1.5 to 2.5%

8. The process according to any of claims 1 to 7, characterized in that the portion of the powder enamel composition that has not been deposited and retained by the object is collected by a suction filtration system and recycled to the electrostatic deposition apparatus.

9. The process according to any of claims 1 to 8, characterized in that the firing or baking temperature after electrostatic deposition is 600-650 ° C.

10. The objects, and particularly bottles and flasks, characterized in that they include a decoration obtained by implementing the process according to any of claims 1 to 9. The objects according to claim 10, characterized in that they consist for example of bottles or jars, which include visual effects for decorative and / or informative purposes, such as, on the one hand, satiny, white or colored bottles and, on the other hand, bottles that include deposits that form graphics and / or information related to a product contained in those bottles, or bottles that include such a satin and such deposits simultaneously.