WO2023046696A1 - Cullet for flat glass - Google Patents

Abstract

The invention relates to a method for preparing a cullet suitable for the manufacture of flat glass, characterised in that it implements a step of grinding an entire multiple glazing unit (1) suitable for the building industry, said multiple glazing unit (1) comprising at least two glass panes (3) separated at the periphery by a non-metallic spacer frame (4) and at least one polymer-based sealing gasket (5A, 5B).

Description

Description

Title of the invention: CALCINE FOR FLAT GLASS

The present invention relates to the field of glazing for vehicles or buildings for interior and exterior applications and more specifically, to the recycling of used multiple glazing (glazing for vehicles, single, double or triple glazing for buildings, etc.). ). The invention relates in particular to a process for the preparation of a cullet suitable for the manufacture of flat glass. The invention also relates to a cullet obtained via this preparation, a composition of raw materials incorporating such a cullet, and a process for manufacturing flat glass from such a composition of raw materials.

[0002] The recycling of multiple glazing is today a problem of primary importance, having in particular for stakes the reduction of the costs of vitrifiable raw material and the reduction of the environmental footprint of the newly manufactured products.

Such multiple glazing is generally in the form of double glazing or triple glazing. The term “double glazing” means a set of two glazing units spaced apart and separated by a gas or vacuum layer and by “triple glazing” a set of three glazing units spaced apart and separated by two respective layers of gas or vacuum. Traditionally, the single glazing units are separated two by two by an intermediate frame (spacer) made of metal, generally aluminum, as well as by sealing joints to ensure the tightness of the gas gaps.

[0004] In known manner, glass is entirely recyclable. However, the same is not true of non-glass materials (as opposed to the glass of the glazing) and in particular of the metal spacer frame which, when introduced into a glass furnace, significantly impairs the quality of the glass produced. For this reason at least, the recycling in the state of such multiple glazing for the manufacture of flat glass is currently prohibited. In practice, such waste glass is diverted to glass wool or bottle manufacturing lines, which are relatively more tolerant of defects that may be caused in the glass, compared to the flat glass industry. [0005] In a problem of recycling for the manufacture of flat glass, it is now necessary to separate the glass from the other components (non-glass) of the multiple glazing. Such a separation is traditionally carried out mechanically, that is to say via a direct contact action, and necessarily involves the destruction of one or more of the components of said glass function assembly, and in particular of the glazing(s). Evidenced by the patent document WO2020/002640 which relates to the fragmentation of used windows, with a view to their recycling. During the entire stage of this process, there is a risk of the multiple glazing breaking and of the cullet being polluted by non-vitreous materials. The implementation of such a recycling circuit also involves transporting the used multiple glazing to a site equipped with a dedicated recycling installation, which constitutes an additional logistical constraint.

[0006] The proposed technique makes it possible to respond to the aforementioned drawbacks and relates more particularly, in at least one embodiment, to a process for preparing a cullet suitable for the manufacture of flat glass, characterized in that it implements a step of grinding all of a multiple glazing suitable for the building, for example a triple glazing, preferably a double glazing, said multiple glazing comprising at least two glazing separated at the periphery by a non-metallic spacer frame and at least one sealing joint of a polymeric nature, said cullet being obtained directly after said grinding step.

[0007] Throughout the description, cullet designates glass debris from flat glass production lines and/or (de)construction sites. According to the invention, such a cullet is obtained directly after grinding or in other words, subsequently, without any intermediate cullet treatment step being implemented. By definition, "grinding" means the reduction of cullet to powder, by shock or by pressure.

[0008] Such a cullet is suitable for the manufacture of flat glass in that it has a very low content of non-glass materials, in order to meet the particularly demanding glass quality criteria in this specific field.

The invention is based on a new and inventive concept consisting in manufacturing cullet from multiple glazings which can be completely reintroduced in a glass furnace for flat glass, including the spacer frame and the sealing joints. The logistical management of the recycling circuit for such multiple glazings is therefore greatly simplified.

[0010] Such multiple glazings have in particular the specificity of implementing, on the one hand, glazings whose composition is close to that of the flat glass to be produced, effectively excluding complex glazings rich in non-glass materials - such as by example electrochromic glazing - and on the other hand spacers which, due to their non-metallic composition, significantly limit the risks of contamination of the glass bath. The invention thus makes it possible to recycle multiple glazings without sacrificing the quality of the flat glass manufactured.

[0011] According to a particular embodiment, said spacer frame is at least partly coated with a metal sheet, preferably aluminum, with a thickness of between 1 nanometer and 10 micrometers.

[0012] The finer the metal sheet, the less the destabilization of the glass bath.

According to a particular embodiment, said spacer frame belongs to the group comprising polyethylene (PE), polycarbonates, polypropylene (PP), polystyrene, polyesters, polyurethanes, polymethylmethacrylates, polyacrylates, polyamides, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), and preferably acrylonitrile-butadiene-styrene (ABS), acrylic ester-styrene-acrylonitrile (ASA), PET/PC, PBT/PC and/or copolymers or mixtures thereof, and is reinforced with fiberglass in a content of between 20% and 50%, preferably between 30% and 40%.

According to a particular embodiment, said spacer frame is at least partially filled with desiccant balls whose diameter is less than 2.0 millimeters, preferably equal to 0.7 millimeters.

[0015] The use of desiccant balls makes it possible to reduce the humidity within the layer of inert gas. The smaller the size of the beads, the easier their disintegration within the glass bath. The risk of faults appearing is therefore reduced. According to a particular embodiment, said desiccant beads belong to the group comprising silica gels, molecular sieves, CaCl2, Na2SO4, activated carbon, silicates, bentonite, zeolites and mixtures thereof .

[0017]According to a particular embodiment, said multiple glazing comprises an interior polyisobutylene seal and an exterior polyurethane, polysulphide and/or silicone seal.

[0018] The invention also relates to a cullet obtained by such a preparation process, characterized in that it comprises non-glass materials resulting from the grinding of said non-metallic spacer frame and of said sealing joint of a polymeric nature.

[0019] According to a particular embodiment, the mass concentration of non-glass materials is less than 100,000 ppm, preferably less than 10,000 ppm, preferably less than 5,000 ppm, preferably less than 2,500 ppm.

[0020] According to a particular embodiment, the non-glass materials have a grain size of less than 20 millimeters, preferably less than 10 millimeters.

What is called the size of a grain is in fact its "equivalent diameter" (De). In a known manner, such a grain size is measured by means of a sedimentation particle sizer.

According to a particular embodiment, the concentration of metallic materials is less than 6.000 ppm, preferably less than 0.024 ppm.

In practice, a concentration of metallic materials between 0.024 ppm and 6 ppm corresponds to the implementation of metal sheets with a thickness between 30 nm and 7 microns. The value of 6 ppm is the upper concentration limit above which the quantity of metallic materials tends to destabilize the glass bath in a prohibitive manner. In order to preserve the glass bath, it is preferable for the concentration of metallic materials to be as low as possible. [0024] According to a particular embodiment, the metallic materials have a grain size of less than 20,000 micrometers, preferably less than 10,000 micrometers, preferably less than 5,000 micrometers.

What is called the size of a grain is in fact its “equivalent diameter” (De). In a known manner, such a grain size is measured by means of a sedimentation particle sizer. The smaller the grain size, the better its absorption by the glass bath.

The invention also relates to a composition of raw materials suitable for the manufacture of flat glass, characterized in that it comprises such a cullet.

According to a particular embodiment, the cullet has a mass concentration less than or equal to 100%, preferably less than or equal to 70%, preferably less than or equal to 40%, preferably less than or equal to 25%, preferably less than or equal to equal to 10%, preferably less than or equal to 8%, preferably less than or equal to 6%.

The choice of such a mass concentration of cullet according to the invention depends on the content of the latter in non-glass materials, and in particular in metallic materials. A research program conducted by the inventors has made it possible to demonstrate that the quality of the flat glass obtained remains unchanged (and therefore optimal) if the mass concentration within the glass bath of the assembly comprising the spacers, the desiccant and the sealing joints remains below 0.25%.

The invention also relates to a process for manufacturing flat glass, characterized in that it comprises a step of melting such a composition of raw materials.

[0030] Such a process allows the manufacture of flat glass while reducing the associated costs of vitrifiable raw materials, and reducing the environmental footprint of the newly manufactured flat glass.

[0031] Other characteristics and advantages of the invention will appear on reading the following description of particular embodiments, given by way of simple illustrative and non-limiting examples, and of the appended figure, for which:

[0032] [Fig. 1] Figure 1 is a schematic sectional representation of a multiple glazing adapted to be crushed, during the implementation of a cullet manufacturing process according to a particular embodiment of the invention,

[0033] [Fig. 2] figure 2 is a schematic representation of a curve of variation of the RedOx of the glass bath, as a function of the mass concentration of non-glass components,

[0034] [Fig. 3] figure 3 is a schematic representation of a curve of variation of the mass percentage of sulfur trioxide (SO3) in the glass bath, as a function of the mass concentration of non-glass components.

The various elements illustrated by the figures are not necessarily represented on a real scale, the emphasis being more on the representation of the general operation of the invention. In Figure 1, unless otherwise indicated, reference numerals which are identical represent similar or identical elements. A particular embodiment of the invention is described below. It is understood that the present invention is in no way limited by this particular embodiment and that other embodiments can be perfectly implemented.

[0036] Figure 1 illustrates a multiple glazing (1) adapted to be crushed, during the implementation of a cullet manufacturing process according to a particular embodiment of the invention. Such a multiple glazing is a double glazing (1) which comprises a layer of inert gas (argon) (2) partitioned between two substrates (3) by means of a non-metallic spacer frame (4), primary sealing joints (5A) and secondary sealing joints (5B) arranged on the periphery of the two substrates (3). Due to their composition of polymeric nature, and therefore non-metallic, the spacers forming the intermediate frame (4) significantly limit the risks of contamination of the glass bath.

[0037] In order to assess the impact of the mass concentration of non-glass components on the stability of the glass bath, a test campaign was implemented on an experimental furnace, during which non-glass components glassmakers were introduced into the glass bath, according to predetermined mass proportions. So that the results obtained best correspond to the industrial reality of a flat glass production furnace into which cullet would be introduced including crushed insulating glazing units with their non-glass components, these non-glass components were made up of 50% by mass of sealing polyurethane secondary, 27% by mass of a polymeric interlayer called Swisspacer®, which is marketed by the Saint-Gobain group and comprises in particular a thin aluminum strip, 20% by mass of desiccant beads, and 3% by mass of polyisobutylene primary sealing gasket. Such a distribution corresponds to that usually observed in a double glazing equipped with such a Swisspacer® spacer and having a cavity 16 mm thick.

[0038] Figure 2 illustrates the variation of the RedOx of the glass bath, as a function of the mass concentration of non-glass components. Here, “RedOx” is defined as the molar content of ferrous iron in the glass relative to its molar content of total iron. This term reflects the redox state of the glass, which greatly influences the physico-chemical properties of the glass. This RedOx has an influence on the kinematics of the glass bath, as well as on the color of the glass obtained. A range of maximum variation of this RedOx is determined beforehand, taking as a reference a glass bath from a composition not presenting any particular impurity. This reference range is illustrated in Figure 2 by two horizontal lines corresponding to RedOx values of 0.19 (lower limit) and 0.24 (upper limit).

Figure 3 illustrates the variation of the mass percentage of sulfur trioxide (SO3) in the glass bath, depending on the mass concentration of non-glass components. As for RedOx, a range of maximum variation in the mass content of SO3 is determined beforehand, taking as a reference a glass bath resulting from a composition not presenting any particular impurity. This reference range is illustrated in Figure 3 by two horizontal lines corresponding to SO3 mass contents of 0.31% (lower limit) and 0.36% (upper limit). Outside this range of values, foam is generated in the glass bath, which is a source of possible defects in the glass produced. The exploitation of the results obtained makes it possible to conclude that the mass proportion of non-glass products that can be introduced into the glass bath without destabilizing the latter, and therefore without causing any damage to the quality of the glass produced, is 0 .25% by mass. The introduction of non-glass materials in higher mass proportions could be envisaged, but this would result in an increasing deterioration in the quality of the glass obtained.

Claims

-9- Claims [Claim 1] 1 . Process for the preparation of a cullet suitable for the manufacture of flat glass, characterized in that it implements a step of grinding the entirety of a multiple glazing (1) suitable for the building, for example a triple glazing , preferably double glazing (1), said multiple glazing (1) comprising at least two glazings (3) separated at the periphery by a non-metallic spacer frame (4) and at least one sealing joint (5A, 5B) of polymer, said cullet being obtained directly after said grinding step. [Claim 2] 2. Process for preparing a cullet according to one of the preceding claims, characterized in that said intermediate frame (4) is at least partly coated with a metal sheet, preferably aluminum, of a thickness between 1 nanometer and 10 micrometers. [Claim 3] 3. Process for preparing a cullet according to one of the preceding claims, characterized in that said intermediate frame (4) belongs to the group comprising polyethylene (PE), polycarbonates, polypropylene (PP), polystyrene, polyesters, polyurethanes, polymethylmethacrylates, polyacrylates, polyamides, polyethylene terephthalate (PET), polybutylene terephthalate (P BT), and preferably acrylonitrile-butadiene-styrene (ABS), ester acrylic-styrene-acrylonitrile (ASA), PET/PC, PBT/PC and/or copolymers or mixtures thereof, and is reinforced with fiberglass in a content of between 20% and 50%, preferably between 30% and 40 %. [Claim 4] 4. A process for preparing a cullet according to one of the preceding claims, characterized in that said spacer frame (4) is at least partially filled with desiccant balls whose diameter is less than 2.0 millimeters , preferably equal to 0.7 millimeters. [Claim 5] 5. Process for preparing a cullet according to claim 4, characterized in that said desiccant beads belong to the group comprising silica gels, molecular sieves, CaCl2, Na2SO4, activated carbon, silicates, bentonite, zeolites and mixtures thereof. [Claim 6] 6. Process for preparing a cullet according to one of the preceding claims, characterized in that said multiple glazing (1) comprises an interior seal (5A) made of polyisobutylene and a seal (5B) exterior in polyurethane, polysulphide and/or silicone. [Claim 7] 7. Cullet obtained by a preparation process according to one of the preceding claims, characterized in that it comprises non-glass materials resulting from the grinding of said non-metallic spacer frame (4) and of said sealing joint ( 5A, 5B) of polymeric nature. [Claim 8] 8. Cullet according to claim 7, characterized in that the mass concentration of non-glass materials is less than 100,000 ppm, preferably less than 10,000 ppm, preferably less than 5,000 ppm, preferably less than 2,500 ppm. [Claim 9] 9. Cullet according to one of claims 7 to 8, characterized in that the non-glass materials have a grain size of less than 20 millimeters, preferably less than 10 millimeters. [Claim 10] 10. Cullet according to one of claims 7 to 9, characterized in that the spacer frame (4), from which the non-glass materials are obtained by grinding, is at least partly coated with a metal sheet , preferably aluminum, with a thickness of between 1 nanometer and 10 micrometers, and in that said non-glass materials have a concentration of metallic materials of less than 6.000 ppm, preferably less than 0.024 ppm. [Claim 11] 11. Cullet according to one of claims 7 to 10, characterized in that the intermediate frame (4), from which the non-glass materials are obtained by grinding, is at least partly coated with a metal sheet , preferably aluminum, with a thickness of between 1 nanometer and 10 micrometers, and in that said non-glass materials comprise metallic materials whose grain size is less than 20,000 micrometers, preferably less than 10,000 micrometers, preferably less than 5000 micrometers. [Claim 12] 12. Composition of raw materials suitable for the manufacture of flat glass, characterized in that it comprises a cullet according to one of claims 7 to 11. -11- [Claim 13] 13. Composition of raw materials according to claim 12, characterized in that the cullet has a mass concentration less than or equal to 100%, preferably less than or equal to 70%, preferably less than or equal to 40%, preferably less or equal to 25%, preferably less than or equal to 10%, preferably less than or equal to 8%, preferably less than or equal to 6%. [Claim 14] 14. Process for manufacturing flat glass, characterized in that it comprises a step of melting a composition of raw materials according to one of claims 12 and 13.