A method for manufacturing glass articles by adding recycled glass to a feeder

Abstract

The present invention is a method for manufacturing glass articles from external cullet and in which the external cullet is added to a molten glass composition present in a feeder.

Description

Title of the invention: Method for manufacturing glass articles by adding recycled glass to a feeder Technical field

[0001] The present disclosure relates to the field of manufacturing glass articles comprising a portion of recycled glass, in particular molded glass articles, more particularly glass perfume bottles. Prior art

[0002] The manufacture of glass articles is a well-known process that uses different thermal equipment including a glass furnace, a feeder and a forming machine. The glass furnace, which operates continuously during a manufacturing cycle that can last six months, ensures the production of the glass by melting a glass composition. The feeder is a conditioning channel that conveys the molten glass composition from the glass furnace to the forming machine. The forming machine shapes a drop of glass obtained from the molten glass composition to manufacture the glass article.

[0003] Processes for manufacturing glass articles introducing into the glass furnace a glass composition comprising virgin raw materials, internal cullet and external cullet are known. EP 3 252 021 describes such a process. These processes make it possible to recycle glass. Since glass is potentially infinitely recyclable, these processes therefore make it possible to limit the environmental impact of glass manufacturing.

[0004] Nevertheless, the manufacturing cost of glass articles manufactured by these processes may be higher than the manufacturing cost of glass articles manufactured by processes not using external cullet. Indeed, the iron content in the external cullet gives the glass article from which it is manufactured a greenish tint which may not be compatible with the use of the glass article. For example, the perfume industry wants a white, colorless, transparent and shiny glass to highlight the fragrance contained in the bottle. To solve this problem, it is necessary to select white external cullet, or even semi-white external cullet, which have the lowest iron contents. This selection increases the production costs of glass articles obtained from external cullet.

[0005] For some glass items, such as perfume bottles, this additional cost may be acceptable. For other glass items, this additional cost may not be acceptable. To adjust the impact of this additional cost, it is possible to adjust the external cullet content in glass items. This nevertheless requires the glassmaker to modify the operating conditions of the glass furnace easily and quickly according to changes in the glass composition recipe.

[0006] The manufacturing process for glass articles, in particular molded glass articles, must meet strict specifications. From the molten glass composition, it must make it possible to reproducibly obtain glass articles that are mechanically resistant and that do not have any appearance defects (e.g., air bubbles). It must also not generate any color drift during the six-month manufacturing cycle. However, various complex physicochemical processes are implemented in the glass furnace, which operates continuously. Any change made to the glass composition recipe alters these various complex physicochemical processes, so that the process no longer meets the specifications. In order for the process to meet the specifications again, it is then necessary to determine the operating conditions of the glass furnace adapted to the modification of the recipe for the molten glass composition. This process is long, complex and requires stopping the glass furnace, which is not possible.

[0007] Thus, the operating conditions of the glass furnace cannot be easily and quickly adapted according to changes in the recipe for the glass composition.

[0008] There is therefore a need for a method of manufacturing, from external cullet, a white, colorless, transparent, shiny glass compatible with use in the cosmetics and perfumery industry, said method being able to adapt quickly and easily to different contents of external cullet in the glass composition.

[0009] It is to the credit of the inventors that they found that it was possible to meet this need by adding a portion of external cullet to the feeder. Summary

[0010] A first aspect of the invention is a method of manufacturing a glass article, in particular a molded glass article, more particularly a glass bottle, from a glass composition, said method comprising the following steps: (a) introducing the glass composition into a glass furnace, the glass composition comprising virgin raw materials for mineral glass, b) melting the glass composition in the glass furnace to obtain a molten glass composition, (c) conveying the molten glass composition from the glass furnace to a forming machine using a feeder, and d) shaping the molten glass composition using the machine forming to obtain the glass article, in particular the molded glass article, more particularly the glass bottle, characterized in that external cullet debris is added to the molten glass composition in the feeder during step c).

[0011] Advantageously, the method of the present invention can be readily adapted to manufacture glass articles over an extremely wide range of external cullet contents, ranging from 0.5% to 50% by weight of the glass articles. Indeed, different external cullet contents can be achieved by only changing the amount of external cullet debris added to the molten glass composition, and therefore without changing the recipe of the glass composition introduced into the glass furnace. Thus, the furnace operating conditions do not have to be adapted during the manufacturing cycle to manufacture glass articles with different external cullet contents.

[0012] Furthermore, unexpectedly, the inventors also observed that this choice of adding the external cullet debris to the glass composition melted in the feeder does not disrupt the process, in particular the shaping step d), and does not cause alterations in the manufactured glass article, such as appearance defects (air bubbles, tint, optical characteristics) or low mechanical strength of the glass article.

[0013] The method of the invention is also simple and economical to implement on an industrial scale. Indeed, the method of the invention does not require heavy investment in equipment since it can be implemented in a conventional glass article production unit, known and mastered by the person skilled in the art.

[0014] By manufacturing glass articles with a high external cullet content, the process of the invention also has a reduced environmental impact. Indeed, it allows for the consumption of less virgin raw materials and is advantageously less energy-intensive. Indeed, the melting of external cullet debris is less energy-intensive and emits less CO2 than the melting of virgin raw materials. Typically, the energy gain is 2.5% per 10% of external cullet debris, the CO2 gain is 580 kg per tonne of external cullet debris and the gain in virgin raw materials is 1.2 tonnes per tonne of external cullet debris.

[0015] The process of the invention also contributes to the circular economy because it allows the recovery of all types of glass, for example: - household glass deposited by residents in containers located near their homes, or collected by a specific door-to-door collection service, - glass from cafes, hotels and restaurants collected using specific containers called barrels, - so-called “industrial hollow” glass or bottles from industrial waste from glass producers, bottlers and distributors. More specifically, the process of the invention makes it possible to recover waste specific to unpolluted bottling and to recycle premium white glass which would have been less recovered in the traditional recycling sector. Description of the embodiments

[0016] A first aspect of the invention is a method of manufacturing a glass article, in particular a molded glass article, more particularly a glass bottle, from a glass composition, said method comprising the following steps: (a) introducing the glass composition into a glass furnace, the glass composition comprising virgin raw materials for mineral glass, b) melting the glass composition in the glass furnace to obtain a molten glass composition, (c) conveying the molten glass composition from the glass furnace to a forming machine using a feeder, and (d) shaping the molten glass composition using the forming machine to obtain the glass article, in particular the molded glass article, more particularly the glass bottle, characterized in that external cullet debris is added to the molten glass composition in the feeder during step c).

[0017] For the purposes of the present application, "external cullet" means used glass typically collected, for recycling, via collection channels. In the method of the present invention, the external cullet is used in the form of debris.

[0018] A frit, a bead and a pellet commonly used to color a glass are not external cullet debris within the meaning of the present application.

[0019] In particular, unlike frits, beads or pellets, commonly added to the molten glass composition in the feeder to color the glass, the external cullet debris of the process of the present invention may be devoid of a fluxing agent. The fluxing agent is used to facilitate the melting of the frit, bead or pellet in the molten glass composition. The melting of the external cullet debris in the molten glass composition is sufficiently good that the addition of a fluxing agent is not necessary.

[0020] The external cullet debris may have a size of 0.1 mm to 50 mm, in particular 0.1 mm to 20 mm, more particularly 0.5 mm to 20 mm, most particularly 1 mm to 6 mm. Depending on the circumstances, the size may be 1 mm to 3 mm or 3 mm to 6 mm.

[0021] Advantageously, a size in these value ranges makes it possible to obtain an article made of glass that does not have any visual defects. Indeed, the inventors have found that if the size of the external cullet debris is smaller than these value ranges then air bubbles are formed in the glass of the article. Without wishing to be bound by any theory, the inventors are of the opinion that these air bubbles are the consequence of bubbles generated in the molten glass composition during the addition of external cullet debris having a size smaller than these value ranges in the molten glass composition. The inventors are also of the opinion that if the size is greater than these value ranges then: - external cullet debris may not have time to melt before the molten glass composition reaches the forming machine. Thus, the glass article cannot be manufactured, and / or - the temperature of the molten glass composition can be lowered to "freeze" the feeder, i.e. create a barrier of cold glass blocking the flow of molten glass composition into the feeder and stopping the process.

[0022] The person skilled in the art can determine the size ranges of the external cullet debris mentioned above by sieving using sieves of suitable opening.

[0023] To obtain external cullet debris having such a size, the external cullet may undergo a prior grinding step.

[0024] Such a grinding step is conventional. The person skilled in the art will know how to implement it to obtain the desired size.

[0025] The external cullet debris may be obtained from post-consumer mineral recycled glass, pre-consumer mineral recycled glass or a mixture thereof, in particular post-consumer mineral recycled glass.

[0026] For the purposes of this application, "post-consumer mineral recycled glass" means the external cullet generated by the end user of the product including the distribution chain in accordance with the ISO 14021 standard (July 2016).

[0027] For the purposes of this application, "pre-consumer mineral recycled glass" means, in accordance with ISO 14021 (July 2016), glass or cullet diverted from the waste stream during a manufacturing step such as the decoration step or the packaging step. Excluded is the reuse of glass or cullet such as those resulting from reprocessing of regrinding, or residues generated during a given process and which can be recovered (for recovery) within the same process which generated them.

[0028] Independently of each other, post-consumer mineral recycled glass and pre-consumer mineral recycled glass may in particular be soda-lime glass such as glass from a molded glass article, solar panel glass, household glass, automotive glass or mixtures thereof, in particular soda-lime glass. calcium such as glass from a molded glass article.

[0029] The external cullet debris may be obtained from post-consumer recycled bottle glass, pre-consumer recycled bottle glass, post-consumer recycled bottle glass, pre-consumer recycled bottle glass or mixtures thereof, in particular post-consumer recycled bottle glass, pre-consumer recycled bottle glass or mixtures thereof.

[0030] This is particularly advantageous because the inventors have found that the fluxing agent can impair the quality of the glass by generating air bubbles in the glass. Without wishing to be bound by any theory, the inventors are of the opinion that these air bubbles are the consequence of bubbles generated in the molten glass composition during the addition of the fluxing agent to the molten glass composition.

[0031] Boron oxide, lithium oxide, sodium oxide, potassium oxide, lithium carbonate, sodium carbonate, and potassium carbonate are examples of commonly used fluxing agents.

[0032] The mass ratio between the external cullet debris and the molten glass composition may be from 0.1:100 to 25:100, in particular from 1:100 to 20:100, more particularly from 2:100 to 10:100.

[0033] The external cullet debris may be added to the molten glass composition in the feeder such that the external cullet weight content in the glass article is from 0.5% to 50% by weight of said article, in particular from 5% to 40%, more particularly from 10% to 25%.

[0034] Since these ranges of external cullet content in the glass article are wide, the method of the invention can manufacture glass articles over a wide range of external cullet contents. Thus, the method of the invention can be adapted depending on the acceptability of the additional cost linked to the introduction of external cullet into the manufactured glass article.

[0035] The external cullet debris may not include internal cullet as defined below.

[0036] For the purposes of the present application, "glass composition" means a vitrifiable mixture of solid components intended to be brought to its melting temperature to change said mixture from the solid state to a liquid state for the purpose of manufacturing the glass article.

[0037] For the purposes of the present application, "molded glass article" means a glass article manufactured by blowing, pressing or a combination of these two techniques and using a mold. For example, the molded glass article may be hollow such as a container or solid such as a stopper or a cabochon. Typically the container may have a narrow neck such as a flask, a bottle, an ampoule, a carafe or a demijohn. The container may alternatively have a wide neck such as a pot or a jar. The container can notably be a perfume bottle or a jar for a cosmetic product.

[0038] For the purposes of the present application, "virgin raw materials" means the materials which are the basis of soda-lime glass, borosilicate glass or opal glass, in particular the basis of soda-lime glass. Typically these materials can be chosen from silica, sodium carbonate, calcium carbonate (also called limestone), barium carbonate, hydrated alumina, sodium sulfate and mixtures thereof, in particular mixtures thereof.

[0039] The virgin raw materials may comprise an iron level less than or equal to 160 ppm, preferably less than or equal to 150 ppm, 140 ppm, 130 ppm or 120 ppm.

[0040] Advantageously, such an iron content in the virgin raw materials makes it possible to manufacture, from external cullet, a glass article which is white, colorless, transparent, shiny and which is compatible with use, for example, as a perfume bottle or a jar for a cosmetic product. Indeed, this iron content makes it possible to maintain an iron level in the manufactured glass article below 250 ppm, a limit value above which the inventors have noted that the greenish tint of the glass appears.

[0041] The temperature of the molten glass composition in the feeder, during step c), may be from 1000°C to 1500°C, in particular from 1050°C to 1400°C, more particularly from 1100°C to 1300°C.

[0042] Such temperatures are common to the conventional method of manufacturing glass articles. The person skilled in the art will therefore be able to simply implement the method of the present invention without having to modify the conventional method of manufacturing glass articles.

[0043] The feeder may include an agitator (“stirrer” according to English terminology).

[0044] The agitator facilitates the homogeneous dispersion of the external cullet debris in the molten glass composition.

[0045] Typically, the agitator may comprise different blades.

[0046] For example, the rotation speed of the agitator blades may be from 5 rpm to 50 rpm, in particular from 10 rpm to 30 rpm, most particularly from 13 rpm to 21 rpm.

[0047] Typically, the proportion of virgin raw materials in the glass composition may be from 20% to 99% by weight of the glass composition, in particular from 30% to 80% by weight, more particularly from 40% to 75% by weight, more particularly still from 55% to 75% by weight, from 65% to 75% by weight or from 40% to 65% by weight. It may, for example, be 40%, 45%, 50%, 53%, 55%, 58%, 60%, 65% by weight.

[0048] The glass composition may further comprise external cullet, cullet internal or both.

[0049] Advantageously, having external cullet in the glass composition facilitates the manufacture of glass articles with a high external cullet content. This is because it reduces the amount of external cullet debris to be added to the molten glass composition in the feeder.

[0050] Typically, the proportion of external cullet in the glass composition may be from 1% to 50% by weight of the glass composition, in particular from 1% to 40%, more particularly from 5% to 40%, more particularly still from 10% to 30%. It may, for example, be equal to 10%, 11%, 12%, 13%, 14%, 15%, 16%, 17%, 18%, 19%, 20%, 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29% or 30% by weight.

[0051] For the purposes of the present application, "internal cullet" means the waste generated by a process for manufacturing glass articles, in particular molded glass articles, carried out on the same industrial site, said glass articles possibly having an appearance defect, air bubbles, a colored tint and / or mechanical fragility.

[0052] Advantageously, the use of internal cullet makes it possible to increase the recycled glass content, and therefore to reduce the virgin raw material content, in the glass composition of the invention. Thus, the consumption of mineral resources by the process of the invention is reduced.

[0053] Typically, the proportion of internal cullet in the glass composition may be from 1% to 50% by weight of the glass composition, in particular from 1% to 40%, in particular from 10% to 50%, more particularly from 25% to 40%.

[0054] The sum of the shares of the constituent elements of the glass composition cannot exceed 100% by weight of the glass composition.

[0055] The glass composition may further comprise a bleaching agent.

[0056] For the purposes of the present application, "bleaching agent" means a powdered agent which modifies the optical properties of the glass, in particular its tint under given lighting and observation conditions.

[0057] The bleaching agent may be chosen from cobalt oxide, cerium oxide, erbium oxide, neodymium oxide, selenium oxide and mixtures thereof, in particular cerium oxide, erbium oxide, neodymium oxide and mixtures thereof, more particularly being a mixture of cerium oxide, erbium oxide and optionally neodymium oxide.

[0058] Advantageously, cerium oxide facilitates the manufacture of a glass article that is as colorless as possible by oxidizing the iron present in the glass composition to its highest oxidation level.

[0059] Erbium oxide, selenium oxide and neodymium oxide advantageously prevent the glass from having a pinkish tint.

[0060] According to a specific embodiment, the bleaching agent is devoid of cobalt oxide, selenium oxide or both. Indeed, selenium oxide can be unstable under the operating conditions of step b) of melting in the glass furnace and give the glass article an unwanted yellow tint.

[0061] The glass composition may comprise, relative to the proportion of virgin raw materials, between 500 ppm and 3000 ppm of bleaching agent.

[0062] Unless otherwise stated, reference is made to ppm (parts per million) by weight.

[0063] Step a) of introducing the glass composition into the glass furnace of the process of the invention can be carried out by any techniques known to those skilled in the art, such as, for example, using a furnace hopper.

[0064] The glass furnace may be any type of furnace capable of carrying out the melting step of the process of the invention, i.e. of bringing the glass composition to its melting temperature to obtain molten glass.

[0065] According to one embodiment, the glass furnace may be a continuous furnace, such as for example a basin furnace continuously supplied with glass composition upstream so as to continuously obtain the molten glass downstream.

[0066] Step c) of conveying the glass composition can be carried out by any techniques known to those skilled in the art using a feeder. Indeed, the addition of the external cullet debris to the molten glass composition can be carried out using a system conventionally used for adding colored pigments to the molten glass composition.

[0067] Step d) of shaping the molten glass to obtain the glass article may, for example, be carried out by any conventional forming machine suitable for manufacturing a glass article, for example, by molding, blowing, pressing and combinations thereof.

[0068] The molten glass composition obtained at the end of melting step b) may not have the appropriate characteristics enabling it to undergo the shaping step. In the process according to the invention, the molten glass composition which does not have the appropriate characteristics to undergo the shaping step can be recycled as internal cullet. Advantageously, this makes it possible to recover waste from the process of the invention. This also makes it possible to maintain the iron content of the manufactured glass article below 250 ppm, the limit value above which the inventors noted that the greenish tint of the glass appeared.

[0069] Thus, according to one embodiment, a portion of the molten glass composition obtained at the end of the melting step may undergo a recycling step as internal cullet of the glass composition. For example, less than 50% by weight, in particular 30% to 40% by weight, of the molten glass composition obtained at the end of the melting step may undergo this recycling step. Examples

[0070] Glass perfume bottles are manufactured from a glass composition whose composition is shown in Table 1 below.

[0071] [Tables 1] Elements introduced into the furnace Content External cullet 9.89% Internal cullet 26.98% Virgin raw materials 63.13% Bleaching agent 1700 ppm % by weight calculated in relation to the total mass introduced into the furnace ppm by weight expressed in relation to virgin raw materials

[0072] The glass composition is melted in a glass furnace and then conveyed using a feeder to a forming machine to manufacture the glass perfume bottles.

[0073] The feeder includes 3 batteries of 2 agitators.

[0074] Two 7-hour tests are carried out with two types of external cullet debris.

[0075] The first external cullet debris is added to the molten glass composition in the feeder under the conditions indicated in Table 2 below.

[0076] The second external cullet debris is added to the molten glass composition in the feeder under the conditions indicated in Table 3 below.

[0077] Regardless of the external cullet debris added to the molten glass composition, glass perfume bottles are continuously manufactured during the two 7-hour tests. The manufactured bottles are compatible with use by the cosmetics and perfumery industry. Size of external cullet debris Mass of molten glass composition fed into a feeder per day Mass ratio of external cullet debris: molten glass composition Agitator speed Temperature Feeder inlet Agitators Feeder middle Before feeder from 2 mm to 4 mm 14 tonnes 2:100 1st battery: 19 2nd battery: 21 3rd battery: 19 1300°C 1300° C 1200°C 1170°C Size of external cullet debris Mass of molten glass composition fed into a feeder per day Mass ratio of external cullet debris: molten glass composition Agitator speed Feeder temperature Agitators Feeder medium Before feeder from 4 mm to 5 mm 14 tonnes 2:100 1st battery: 19 2nd battery: 21 3rd battery: 19 1300°C 1300° C 1200°C 1170° C

Claims

Claims

1. A method of manufacturing a glass article from a glass composition, said method comprising the following steps: a) introducing the glass composition into a glass furnace, the glass composition comprising virgin raw materials for mineral glass, b) melting the glass composition in the glass furnace to obtain a molten glass composition, c) conveying the molten glass composition from the glass furnace to a forming machine using a feeder, and d) shaping the molten glass composition using the forming machine to obtain the glass article, characterized in that external cullet debris is added to the molten glass composition in the feeder during step c).

2. The method of claim 1 wherein the external cullet debris has a size of 0.1 mm to 50 mm.

3. A method according to claim 1 or claim 2 wherein the external cullet debris is free of fluxing agent.

4. A method according to any one of claims 1 to 3 wherein the external cullet debris is added so that the external cullet content in the glass article is 0.5% to 50% by weight of said article.

5. A method according to any one of claims 1 to 4 wherein the temperature of the molten glass composition during step c) is from 1000°C to 1500°C.

6. A method according to any one of claims 1 to 5 wherein the feeder comprises an agitator comprising different blades.

7. A method according to any one of claims 1 to 6 wherein the speed of the agitator blades is from 5 rpm to 50 rpm.

8. A process according to any one of claims 1 to 7 wherein the proportion of virgin raw materials in the glass composition is from 20% to 99% by weight.

9. A method according to any one of claims 1 to 8 wherein the glass composition further comprises external cullet, internal cullet or both.

10. A method according to claim 9 wherein the proportion of external cullet in the glass composition is from 1% to 50% by weight of the glass composition.

11. A method according to claim 9 or claim 10 wherein the portion of internal cullet in the glass composition is from 1% to 50% by weight of the glass composition.

12. A method according to any one of claims 1 to 11 wherein the glass composition further comprises a bleaching agent.

13. A method according to claim 12 wherein the composition comprises, relative to the proportion of virgin raw materials, from 500 ppm to 3000 ppm of bleaching agent.

14. A method according to any one of claims 1 to 13 wherein the glass article is a flask, bottle, ampoule, carafe, demijohn, pot or jar.

15. A method according to any one of claims 1 to 13 wherein the glass article is a stopper or a cabochon.