RU2799011C2 - Hiss-stimulating container - Google Patents

Abstract

FIELD: containers for liquids.

SUBSTANCE: invention relates to products in the form of glasses. The present invention discloses a beverage container (1) and a method for manufacturing a beverage container (1) having surface irregularities inside the container. The beverage container (1) is made of glass or ceramic and has surface irregularities inside the container. Irregularities form bubble formation zones inside the container upon contact with a carbonated drink, said zone contains an enamel layer (10) covering the selected area, enamel granules (12) located on the surface of said enamel layer (10) and attached to said enamel layer (10), and a hydrophobic layer (13) located on the surface of said enamel granules (12) to cover at least partially the surface of said enamel granules (12).

EFFECT: present invention makes it possible to supply a carbonated beverage to containers which results in effervescence or bubble formation phenomena and foam accumulation on the surface.

14 cl, 5 dwg

Description

The present invention relates to the field of containers for liquids, in particular to products in the form of glasses.

In the production of beverage containers such as glass goblets, the surfaces to be created are usually made as smooth as possible, in particular for good transparency and for aesthetic reasons.

The supply of a carbonated beverage in containers results in effervescence or bubble formation and accumulation of foam on the surface. For example, for serving beer or sparkling wine, it is desirable to create and maintain effervescence. The areas where bubbles form in a glass container are called nucleation sites.

It has been found that the presence of irregularities on the surfaces of the container upon contact with a carbonated beverage contributes to the formation of bubbles from the gas dissolved in said carbonated beverage. Therefore, in order to promote the formation of bubbles, internal surfaces with rough relief were created in the containers. When filling a container with a liquid containing carbon dioxide, such as a carbonated drink, the irregularities on the inner surface trap air pockets. The interfaces between liquid and air pockets provide better gas exchange. Thus, irregularities form nucleation zones.

European patent EP 0703743 issued to Charles Glassware describes a method of applying material to a surface to create nucleation sites and improve bubble formation. Darkening of the bottom of the glass container was sometimes observed. Patent application FR 2531891 describes a method for removing material that contributes to the formation of an outgassing zone. Application examples are given in international application WO 2010/048488.

FR 3008295 proposes to create nucleation sites within a beverage container by surface irregularities in a selected area of the container, which is then coated with a hydrophobic layer in the selected area.

Application FR No. 1753464 will be published after the filing date of this document.

The Applicant has identified a need to further improve the quality of bubble formation in order to cater to the broader market for low alcohol and/or low dissolved carbon dioxide beers. The quality of the bubble formation includes the consistency of the bubble formation and hence the reproducibility of the manufacture of the container. It required simple fabrication.

Prof. Liger-Belair and his team at UMR CNRS 7331 - University of Reims Champagne-Ardenne published a paper on effervescence:

Liger-Belair, G. “The physics behind the fizz in champagne and sparkling wines” European Physical Journal: Spécial Topics 201, 1–88, 2012.

Liger-Belair, G. “La physique des bulles de champagne” Annales de Physique (Paris) 27(4), 1–106, 2002.

Liger-Belair, G.; Conreux, A.; Villaume, S.; Cilindre, C. “Monitoring the losses of dissolved carbon dioxide from laser-etched champagne glasses” Food Research International, 54, 516–522, 2013.

Liger-Belair, G.; Voisin, C.; Jeandet, P. “Modeling non-classical heterogeneous bubble nucléation from cellulose fibers: Application to bubbling in carbonated beverages” Journal of Physical Chemistry B 109, 14573–14580, 2005.

Liger-Belair, G.; Parmentier, M.; Jeandet, P. “Modeling the kinetics of bubble nucleation in champagne and carbonated beverages” Journal of Physical Chemistry B 110, 21145–21151, 2006.

Liger-Belair, G. “How many bubbles in your glass of bubbly?” Journal of Physical Chemistry B 118, 3156–3163, 2014.

Liger-Belair, G.; Bourget, M.; Villaume, S.; Jeandet, P.; Pron, H.; Polidori, G. “On the losses of dissolved CO2 during champagne serving” Journal of Agricultural and Food Chemistry 58, 8768–8775, 2010.

It is desirable to have a container for drinking beer that provides satisfactory bubble formation for the large number of types of beer it can hold and is stable during use of the container, whether the container is dry or damp, in particular at the outlet of the dishwasher or during the time of subsequent filling, to obtain an equivalent formation of bubbles.

The present invention improves the situation in particular with regard to the applicant's last two aforementioned patents.

Applicant proposes a container based on glass or ceramics for beverages having surface irregularities in a selected area. The irregularities form nucleation sites within the container, with the nucleation sites contributing to the formation of bubbles upon contact with a carbonated beverage. The container contains an enamel layer covering a selected area, a plurality of enamel granules located on the surface of said enamel layer and attached to said enamel layer, and a hydrophobic compound located on part of the surface of said enamel granules.

Enamel grains coated with a hydrophobic coating, bonded to the enamel layer to which they are attached, form nucleation sites. Wash resistance is excellent, in particular over 500 dishwasher cycles with bubble retention in a dry or wet container.

In one embodiment, said enamel layer has a melting point lower than the melting point of the enamel granules. The enamel granules at least partially retain the shape they had prior to being attached to said enamel layer.

In one embodiment, said enamel layer has a thickness of 5 to 100 µm, preferably 10 to 25 µm. At a thickness of less than 5 µm, there is a risk of attaching an insufficient amount of enamel granules, in particular, insufficient surface density of the enamel granules. At thicknesses greater than 100 µm, some enamel granules may be excessively deepened into said enamel layer. The preferred range of 10 to 25 µm results in a low content of loose enamel granules and a roughness favorable to bubble formation.

In one embodiment, said enamel granules have a particle size distribution of 1 to 500 µm, more preferably 50 to 250 µm. Enamel granules smaller than 1 µm are difficult to work with, and their surface, coated with a hydrophobic layer, is less resistant to washing in dishwashers. When the size of the granules is more than 500 microns, some of the bubbles stagnate at the bottom of the container. Therefore, less foam is produced. The appearance of the container differs from those used for carbonated drinks, in particular,

roughness is visible to the naked eye. The preferred range of 50–250 µm results in the correct surface density of the enamel granules and the percentage of area occupied by the enamel granules that promotes blistering.

In one embodiment, said enamel granules are sized such that D10 is 30 to 90 µm, where D10 is the diameter below which 10% of the granules by volume are, D50 is 100 to 145 µm, where D50 is the diameter , below which are 50% of the granules by volume, and D90 is from 150 to 250 μm, while D90 is the diameter below which are 90% of the granules by volume. The proportion of small particles and the proportion of large granules is low. The attachment observed is of good quality and strength.

In one embodiment, D10 is 35 to 50 microns, D50 is 105 to 120 microns, and D90 is 160 to 190 microns. Reduced loss of enamel granules upon attachment.

In one embodiment, said enamel granules have a distributed size with a peak in the range of 80 to 200 µm, preferably 100 to 130 µm. This peak is unique. The roughness ensures satisfactory bubble formation.

In one embodiment, the container is made of soda-lime glass.

In one embodiment, the container is made of crystal. The crystal contains PbO, BaO, K ₂ O and ZnO, in the amount of more than or equal to 10% by weight.

In one embodiment, the hydrophobic compound contains Si. The hydrophobic compound is resistant to temperatures over 600 °C.

In one embodiment, the enamel of the enamel granules is substantially free of Pb, preferably without intentional addition of Pb. Enamel granules have high hardness and melting point.

The Applicant proposes a method for making glass of a beverage container having surface irregularities in a selected area, the irregularities forming nucleation sites within the container, the nucleation sites promoting bubble formation upon contact with a carbonated beverage, comprising applying a layer of enamel covering the selected area, then applying a plurality of enamel granules on the surface of said enamel layer, and baking said enamel layer, and attaching enamel granules to said enamel layer by the same heat treatment, wherein the enamel granules contain a hydrophobic compound placed on a portion of the surface of said enamel granules.

In one embodiment, the maximum temperature reached during the heat treatment is between the melting temperature of the enamel layer and the melting temperature of said enamel granules. The maximum temperature that can be reached is 700 °C.

In one embodiment, the enamel granules consist of a refractory glaze.

In one embodiment, raw enamel granules are mixed with polysilazane, the mixture is baked to a solid, and the solid is broken up to substantially return to the size of the original enamel granules. The term "raw" here is understood as not containing a hydrophobic compound.

In one embodiment, a mixture of raw enamel granules and polysilazane is obtained in a ratio of 8/1 to 15/1.

In one embodiment, the mixture is prepared at 150 to 200°C for a period of 30 to 150 minutes.

In one embodiment, the solid is broken down by grinding. Grinding allows you to separate the solid. Pre-baking may cause agglomeration into a massive solid.

In one embodiment, the ground material is passed through at least one sieve. The size of the granules is controlled.

In one embodiment, the pulverized material, preferably screened, is applied to the enamel layer.

In one embodiment, the application of the ground material to the enamel layer is carried out by pad printing. Carry out the hardening step.

In one embodiment, the hydrophobic compound is derived from a polysilazane.

The container, among other things, may contain a glass body. Transparency allows you to visualize the appearance and movement of bubbles from the place of origin to the surface of the drink.

Other features, details and advantages of the present invention will become apparent upon reading the detailed description below and the accompanying drawings, in which:

- in Fig. 1 shows a sectional view of the container,

- in Fig. 2 is a detailed view of FIG. 1,

- in Fig. 3 is a view similar to that of FIG. 1, in the presence of carbonated beverage,

- in Fig. 4 is a top view at high magnification, and

- in Fig. 5 is a comparative photograph of an embodiment of the present invention and a glass container provided with only a layer of enamel.

The drawings and the following description essentially contain elements with certain reference numbers. Thus, they can not only serve to better understand the present invention, but also contribute to its definition, if necessary.

In the food liquid, the carbon dioxide (CO ₂ ) dissolved in the liquid phase is the carrier gas for the effervescence phenomenon. The frequency of bubble emission during tasting, the size of the bubbles in the container, and the number of bubbles that can form are related to a number of physico-chemical parameters of the liquid phase and the container in which the tasting is carried out.

When a gas contacts a liquid, some of that gas dissolves into the liquid. The solubility of a gas in a liquid is affected by various factors, in particular temperature and pressure. At equilibrium, there is a proportionality between the concentration in the liquid phase of a chemical i, denoted C _i , and its partial pressure in the gas phase P _i . Henry's law is written as:

The coefficient of proportionality k _H is called Henry's constant. It depends strongly on the gas and liquid under consideration, as well as on the temperature.

At normal atmospheric pressure P _o ≈ 1 bar, taking into account the solubility of CO ₂ in beer at 4 °C, which is k _H ≈ 2.6 g/l/bar, while this beer is able to dissolve approximately 2.6 g/l CO ₂ .

When a chemical i is in equilibrium on both sides of the gas/liquid interface, its concentration in the liquid follows Henry's law. Thus, we can say that the liquid is saturated with respect to this substance. In this case, saturation means balance.

When the concentration c _l of chemical i in a liquid is higher than expected from Henry's law, the liquid is supersaturated with respect to that substance. To quantify this out-of-equilibrium situation, the supersaturation factor S _i is defined as the relative excess of the liquid concentration of substance i with respect to a reference concentration, denoted c _o (chosen as the equilibrium concentration for this substance at a partial pressure equal to the liquid pressure P _l ). Therefore, the supersaturation coefficient Si is determined in the following form:

When a liquid is supersaturated with respect to a chemical, S _i > 0. The liquid removes some of its content in that chemical in order to restore a new state of equilibrium, which is in accordance with Henry's law.

Under tasting conditions in a container, the pressure that is established in the liquid is nearly identical to atmospheric pressure. Given the low height of the liquid, which does not exceed 20–25 cm, the effect of hydrostatic overpressure, which is established at the bottom of the container, is insignificant compared to atmospheric pressure. Thus, at a temperature of 4 °C, the concentration at equilibrium can be derived as:

Not all beers have the same concentration of dissolved CO ₂ . Some of them have a low gas content of 3–4 g/l, while others have a high content, up to 7–8 g/l. Their respective supersaturation coefficients in relation to dissolved CO ₂ ,

therefore, they will not be the same. In the case of an average beer, the gas content is approximately 5 g/l. Its supersaturation coefficient (at 4 °C) according to the formula [2]:

In comparison (also at 4°C) highly carbonated water (such as Badoit Rouge) has a supersaturation factor of around 1.3, while champagnes (still young) have much higher ratios of around 3.4. In general, the higher the supersaturation factor of a liquid containing dissolved CO ₂ , the more intense will be the kinetics of escape of dissolved carbon dioxide to restore Henry's equilibrium. However, it has been observed that supersaturation of a liquid with dissolved gas is not necessarily synonymous with bubble formation and hence effervescence.

Indeed, at supersaturation values of beer, the formation of bubbles requires the presence of gas pockets in the medium, the radius of curvature r _C of which exceeds the so-called critical value, defined as follows:

where γ is the surface tension of the liquid, P _o is the ambient pressure, and S is the supersaturation coefficient of the liquid phase with CO ₂ .

At normal atmospheric pressure of 1 bar and 4 °C for beer, which typically has a surface tension of 45 mN/m and a supersaturation factor of about 0.9, the previous equation shows a critical radius of the order of 1 µm, below which bubble formation does not occur.

In order for CO ₂ bubbles to appear and grow in beer, the medium contains gas microbubbles inside, the radii of which exceed this critical radius of the order of 1 µm. We are talking about non-classical heterogeneous nucleation (in contrast to the so-called classical nucleation, which refers to the spontaneous formation, ex nihilo, of bubbles in a highly supersaturated liquid). Conventional nucleation requires very high dissolved gas supersaturation factors (>100) incompatible with carbonated beverages.

The question then arises as to the origin of the rudimentary gas bubbles that are catalysts for the effervescence in the container.

The Applicant has observed in situ the manner in which bubbles of various beers appear, served in smooth glass containers, which thus have not been subjected to any special treatment. In the vast majority of cases, air pockets trapped by particles adsorbed on the glass surface act as a nucleation site. The radius of these gas pockets, trapped in the thick particles (most often cellulose fibers), usually exceeds the critical radius required for the diffusion of dissolved CO ₂ and hence the repeated formation of bubbles in the glass container.

The critical nucleation radius takes into account the concentration of dissolved CO ₂ dissolved in beer, see equations [4] and [5]. However, after application, the indicated concentration is no longer the same as initially. Submission is a critical step. Indeed, pouring into a container creates significant turbulence that accelerates the escape of dissolved carbon dioxide. The colder the beer, the more dissolved carbon dioxide remains dissolved at the time of serving. Indeed, the colder the beer, the more viscous it is. However, the rate of diffusion of dissolved CO ₂ from the beer is higher the lower the viscosity of the beer. In addition, the more viscous the beer, the more effectively turbulence is reduced during pouring. Therefore, the colder the beer is served, the better the dissolved carbon dioxide is retained during serving.

- For St Omer beer served at 4°C in a smooth glass container, the critical radii are 1.02 ± 0.02 µm.

- For Carlsberg beer served at 4°C in a smooth glass container, the critical radius is 1.05 ± 0.02 µm.

In addition, it was found that the flow of bubbles, that is, the number of bubbles per second, is proportional to the square of the temperature, the concentration of CO ₂ dissolved in the liquid, and inversely proportional to the dynamic viscosity of the liquid (in kg/m/s).

On a container filled with beer, according to one embodiment, it was observed that the head height was essentially the same regardless of whether the container was dry at room temperature or wet at dishwasher exit temperature.

In addition, the Applicant has conducted tests comparing a glass container according to one embodiment and a glass container according to FR 3 008 295. three times the diameter. Glass of this shape was used for Amstel®, Kronenbourg®, Heineken®, Foster’s® or Carlsberg® brands, etc. Each room temperature dry glass container was filled with beer at 4–5°C. The beer was left in it for 10 minutes. Then each glass container was emptied, rinsed with clean water and placed in the same dishwasher.

Each clean glass container was removed from the washer and filled with the same volume of Saint Omer® beer for which it was intended, in continuous motion. The foam height was monitored for 5 minutes after filling. As shown in FIG. 5, the foam height in the glass container provided with only the enamel layer on the right side is lower than in the glass containers according to one embodiment. In three glass containers according to one embodiment, located on the left side, the foam height is satisfactory. Shown in order on the left is the glass container after 300 washes, the glass container after 100 washes and the new glass container. The three foam heights are approximately the same, showing the good washability of the glass container of the present invention.

The quality of bubble formation was examined. The foam lasted approximately 10 minutes.

The presence of a hydrophobic layer prevents water from entering the irregularities and therefore allows the nucleation sites to function just as if the glass container were dry.

What has been tested above with beer containing mainly carbon dioxide also applies to beer containing mainly nitrogen, such as Guinness® Draught, or beer supplied under nitrogen pressure.

One of the advantages is that the application of the hydrophobic layer is carried out on enamel glazes, i.e. before the glass is touched. Reduced interference with the normal glass production process. In other words, a batch of coated enamel glaze can be prepared in advance and used for glass containers of different shapes and sizes for different beers.

Such a container 1 is shown in the figures. The container 1 is here in the form of a glass drinking container. In embodiments, container 1 is in the form of a beer mug, champagne glass, or any other container suitable for holding a carbonated beverage. The method described below is applicable to most carbonated beverage containers or carbonated beverages where fizz control is important, see FIG. 3.

The container 1 here consists of a substantially flat bottom 3 and a side wall 5 essentially shaped like a truncated cone. Container 1 in this case is axisymmetric. In the example described here, the bottom 3 and the wall 5 form an integral main body. The main part has an inner bottom surface and an inner edge surface. The inner surfaces are intended to be in contact with the beverage when container 1 is used.

The container 1 can be obtained by known methods of manufacture, such as pressing, blowing and/or centrifugation. At the outlet, the interior of the container 1 is substantially smooth and uniform. Container 1 is called raw.

In the example described below, the inner surface of the bottom 3 is covered with a layer 10 of enamel. Other parts may be covered in a similar manner, depending on the desired arrangement of the bubbles in the finished container 1, or the bottom 3 may be only partially covered. The inner surface of the edge is usually uncoated.

In one embodiment, the enamel layer 10 is a refractory enamel. The enamel is practically lead-free, more precisely, no lead is intentionally added. The enamel of the enamel layer 10 may correspond to FR 2 825 999, which the reader is requested to refer to.

Optionally, a maximum of 4% by weight of pigment may be added to the mixture prior to hardening. For example, an Iriodin® pigment based on mica and titanium oxide can be added. A pigment containing 51 to 58% mica, 42 to 48% TiO ₂ and not more than 1% SnO ₂ or 66 to 74% mica, 26 to 33% TiO ₂ may be suitable, iron oxide may be present and not more 1% SnO ₂ . The presence of mica and titanium oxide in the form of fine, very refractory particles increases the roughness of the enamel layer 10 .

The enamel layer 10 has a thickness of 5 to 100 µm, preferably 10 to 25 µm.

The enamel layer 10 is attached to the inner surface of the bottom 3. Attachment is achieved by maintaining an elevated temperature of the glass in a temperature range of approximately 600 to 700°C. The enamel layer 10 may have a transformation temperature range of 460 to 500°C, a softening temperature range of 500 to 540°C, with the softening temperature being higher than the transformation temperature.

On the enamel layer 10, the enamel glaze 11 is fixed. Glaze 11 of enamel is granular. The enamel glaze 11 is applied to the enamel layer 10, in particular by pad printing. Hardening causes the enamel layer 10 to soften and the enamel glaze 11 to adhere to the enamel layer 10 . It is possible to slightly dip the enamel glaze 11 into the enamel layer 10 .

The enamel glaze 11 consists of enamel granules 12 coated with a hydrophobic layer 13. The enamel granules 12 consist of enamel which is more fire resistant than the enamel layer 10 . Enamel granules 12 may consist of enamel commonly used for coating food ceramics, the enamel melting to form a clear layer. The granule enamel may be of the trade name Ferro®. On the contrary, according to the present invention, the pellet enamel does not melt. The shape of the enamel granules 12 is usually retained. The granular character remains. The enamel granules 12 are heated during the treatment time at a treatment temperature lower than the temperature at which said enamel granules soften or adhere to each other during the same treatment time.

Enamel glaze 11 may contain by weight: SiO ₂ from 40 to 60%, Al ₂ O ₃ from 2 to 6%, B ₂ O ₃ from 15 to 30%, Li ₂ O from 2 to 6%, Na ₂ O from 5 to 10%, K ₂ O from 2 to 6%, MgO less than 1%, CaO less than 1%, ZrO ₂ from 2 to 6%. Other elements may be present as traces.

In one embodiment, the enamel glaze 11 may contain by weight: SiO ₂ from 40 to 60%, Al ₂ O ₃ not more than 10%, B ₂ O ₃ from 15 to 40%, Li ₂ O from 2 to 6%, Na ₂ O not more than 10%, K ₂ O not more than 6%, MgO less than 1%, BaO not more than 6%, CaO not more than 10%, ZrO ₂ not more than 6%, La ₂ O ₃ not more than 6%, F ₂ less 2%. Other elements may be present as traces. More specifically, in the first embodiment, the enamel glaze 11 contains, by weight:

SiO ₂ from 40 to 60%, Al ₂ O ₃ from 2 to 6%, B ₂ O ₃ from 15 to 30%, Li ₂ O from 2 to 6%, Na ₂ from 5 to 10%, K ₂ O from 2 up to 6%, MgO less than 1%, without intentional addition of BaO, CaO not more than 1%, ZrO ₂ from 2 to 6%, without intentional addition of La ₂ O ₃ , without intentional addition of F ₂ .

In the second embodiment, the enamel glaze 11 contains by weight: SiO ₂ from 40 to 60%, Al ₂ O ₃ not more than 2%, B ₂ O ₃ from 20 to 40%, Li ₂ O from 2 to 6%, Na ₂ O not more than 1%, K ₂ O not more than 1%, no intentional addition of MgO, no intentional addition of BaO, CaO 5 to 10%, no intentional addition of ZrO ₂ , no intentional addition of La ₂ O ₃ , no intentional addition of F ₂ .

In the third embodiment, the enamel glaze 11 contains by weight: SiO ₂ 40 to 60%, Al ₂ O ₃ 5 to 10%, B ₂ O ₃ 15 to 30%, Li ₂ O 2 to 6%, Na ₂ O 1 to 5%, K ₂ O 2 to 6%, MgO less than 1%, BaO 2 to 6%, CaO less than 1%, ZrO ₂ 2 to 6%, La ₂ O ₃ 2 to 6 %, F ₂ less than 2%.

The transformation temperature range is from 450 to 550 °C. In the range of transformation temperatures, the transition of glass from a viscoelastic state to a solid glassy state occurs. The transformation temperature can be estimated using a dilatometer. The softening temperature range is 600 to 680°C, more specifically 640 to 650°C. The transformation temperature can be assessed using heated stage microscopy. The transformation temperature can be from 500 to 520 °C.

The enamel glaze 11 is brought to a temperature well below the normal use temperature to enamel a portion of the pottery. Hardening can be carried out at a temperature at which the enamel layer 10 noticeably softens or even begins to melt, while the enamel glaze 11 retains its shape, being far from the melting point. Hardening can be carried out at temperatures between 600 and 700 °C, e.g. 650 °C, within +/- 20 °C.

The difference between the softening temperatures or between the transformation temperatures of the enamel glaze 11 and the enamel layer 10 may be at least 20°C, preferably the difference may be at least 100°C between the softening temperatures.

The hydrophobic layer 13 partially or even completely covers the enamel granules 12. The enamel granules 12 may have uncovered zones 14. The hydrophobic layer 13 contains a polysilazane. In this case, the original product is applied to the enamel granules 12 in the form of a powder. The original product may contain Durazane® 1800 from Merck. The initial product is mixed with the glaze in a weight ratio of the order of 1/10, in particular from 1/8 to 1/15. Thus, the original product is on the surface of the glaze enamel granules. The mixture is brought to 150–200 °C, for example 180 °C. Roasting can last from 30 to 150 minutes, for example 1 hour. Roasting can be done in a baking oven. At the outlet, the mixture has the form of an agglomerated plate. The plate is crushed. Grinding allows you to get a powdery product. Then the enamel granules 12 are covered with a hydrophobic layer 13, some completely, others partially.

The ground material is screened to remove unground material and any fine particles. The unground material can be regrinded or returned to the enamel production line. Fine particles can be returned to the enamel production line. A fine sieve of 40 µm, preferably 50 µm, and a coarse sieve of 500 µm, preferably 250 µm, may be provided. The sieved ground material can be prepared in advance. The screened ground material is suitable for various glass or ceramic containers.

The screened pulverized material is applied to a selected area of the container 1, typically the bottom of the container 1. The application can be done by pad printing. The container 1 is then transferred to a hardening furnace. Hardening attaches the screened ground material to the enamel layer 10 . The crushed material attached to the enamel layer 10 forms surface irregularities. The resulting roughness depends on the amount of glaze, expressed in mass per unit surface or in the number of granules per unit surface, as well as on the size of the granules of the glaze. The hydrophobic layer is preserved during hardening.

In FIG. 4, a sample of enamel layer 10, visible in the background, is covered with glaze 11. Hydrophobic and non-hydrophobic zones are not visible in the selected representation type. The magnification is about 100 times.

The surface irregularities form nucleation sites within the container, in this case at the bottom 3. The nucleation sites promote the formation of bubbles upon contact with the beverage, carbonated carbon dioxide and/or nitrogen.

On a glass container treated in this way, dry beer bubble formation and hot and wet beer bubble formation are nearly identical. The present invention relates in particular to containers made of soda-lime glass or crystal, in particular crystal, without the intentional addition of Pb. Such crystal typically has a Pb content of less than 0.5% by weight.

The present invention is not limited to the examples of methods and containers described above solely by way of example, but it embraces all variations that a person skilled in the art can envision within the scope of the following claims.

Claims (14)

1. A container (1) for drinks made of glass or ceramics, having surface irregularities inside the container, while the irregularities form bubble formation zones inside the container when in contact with a carbonated drink, characterized in that the specified zone contains a layer (10) of enamel covering selected area, enamel granules (12) located on the surface of said enamel layer (10) and attached to said enamel layer (10), and a hydrophobic layer (13) located on the surface of said enamel granules (12) to cover at least partially the surface of said enamel granules (12). 2. Container according to claim 1, characterized in that said enamel layer (10) has a melting point lower than that of enamel granules (12). 3. Container according to claim 1 or 2, characterized in that the enamel layer (10) has a thickness of 5 to 100 µm. 4. Container according to claim 3, characterized in that said enamel layer (10) has a thickness of 10 to 25 µm. 5. A container according to claim 1, characterized in that said enamel granules (12) have a granulometric composition from 1 to 500 µm. 6. A container according to claim 5, characterized in that said enamel granules (12) have a granulometric composition of 50 to 250 µm. 7. Container according to claim 1, characterized in that said enamel granules (12) have such a size that D10 is from 30 to 90 µm, while D10 is the diameter below which 10% of the granules by volume are located, D50 is from 100 to 145 µm, where D50 is the diameter below which 50% of the granules by volume are located, and D90 is from 150 to 250 µm, while D90 is the diameter below which 90% of the granules by volume are below. 8. The container according to claim 7, characterized in that D10 is from 35 to 50 microns, D50 is from 105 to 120 microns, and D90 is from 160 to 190 microns. 9. Container according to claim 1, characterized in that said enamel granules (12) have a distributed size with a peak in the range from 80 to 200 µm. 10. Container according to claim 9, characterized in that said enamel granules (12) have a distributed size with a peak in the range from 100 to 130 µm. 11. Container according to claim 1, characterized in that the container (1) is made of soda-lime glass or crystal. 12. The container according to claim 1, characterized in that the hydrophobic layer contains Si. 13. A method for manufacturing a beverage container (1) having surface irregularities inside the container, wherein the irregularities form bubble formation zones inside the container upon contact with a carbonated beverage, in which an enamel layer (10) is applied covering a selected area, then granules (12) are applied enamel on the surface of said enamel layer (10), and said enamel layer (10) is baked, and enamel granules (12) are attached to said enamel layer (10) by heat treatment, moreover, enamel granules (12) contain a hydrophobic layer (13) placed on part of the surface of said enamel granules (12). 14. Method according to claim 13, characterized in that the heat treatment is carried out at a temperature between the melting temperature of the enamel layer (10) and the melting temperature of said enamel granules (12).

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