A coating roller for applying a liquid
The coating roller with a polymeric layer of specific hardness and flexible foam material addresses the issue of foam generation, ensuring uniform and effective application of heat-sealing primer on glass containers.
Patent Information
- Authority / Receiving Office
- EP · EP
- Patent Type
- Applications
- Current Assignee / Owner
- VERALLIA PACKAGING
- Filing Date
- 2024-12-20
- Publication Date
- 2026-06-24
AI Technical Summary
Existing coating rollers for applying heat-sealing primer on glass containers generate foam between the coating and pressing rollers, leading to non-uniform and unusable coatings due to friction with tubular knit materials, which compromises the application of a homogeneous primer layer.
A coating roller with an outer surface layer of polymeric material having a hardness between 5 ShA and 100 ShA, preferably 20 ShA to 50 ShA, and a flexible layer of foam material, which prevents foam formation and ensures uniform application of the primer.
Prevents foam formation and ensures a homogeneous, uniform coating of the heat-sealing primer on the glass container rims, adhering to food regulations and maintaining primer integrity.
Smart Images
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Abstract
Description
[0001] The present invention relates to a coating roller for applying a liquid (such as a heat-sealing primer, an adhesion promoter or a varnish) onto the rim of a container made of glass (such as a jar, a bottle, a flask or a decanter) and a method of applying the liquid which involves the use of said coating roller.
[0002] The present invention will be here below explained in the reference to the example of the heat-sealing primer without limiting the scope of the present invention. Indeed, the present invention may have an application for other liquids than a heat-sealing primer.
[0003] During glass containers manufacturing, the rim of the glass containers may be coated with a liquid which is called "heat-sealing primer" and which aims to allow the container to be airtight after sealing. The rim is the upper part of a container where aluminum or thermoplastic foil is latter affixed. Indeed, depending on the product it contains, the container undergoes different treatments (for example: steaming, cooling, freezing, pasteurization and sterilization) after being sealed. The application of the heat-sealing primer is carried out to large runs of containers on industrial scale.
[0004] The geometry of the surface of the rim is arbitrary, being often annular, but also oval, substantially rectangular or of some other kind. For technical and economic interests, the aim is to form coatings of heat-sealing primer with a uniform thickness. Indeed, a heat-sealing primer is an auxiliary agent in the heat-sealing of a foil composed of an aluminum foil or a thermoplastic foil and a thermoplastic resin layer.
[0005] It is known that the alkaline constituents of glass are capable of migrating through the coating of heat-sealing primer to its surface, in such a way as to cause leakage problems after heat-sealing. This migration takes place throughout the time for which the containers are stored priorto their use; the longer its duration is, the greater the minimum thickness of primer has to be. Accordingly, an aim is to increase this minimum thickness.
[0006] In so doing, however, it is appropriate to prevent as far as possible nonuniformities in the thickness of the coatings of heat-sealing primer. The aim is therefore to obtain, from this heat-sealing primer, a barrier of relatively large and uniform thickness.BRIEF DESCRIPTION OF THE DRAWINGS
[0007] Fig. 1 is a schematic block diagram of a device for applying a heat-sealing primer on the rim of a glass container. Fig. 2 shows a perspective view of a no-crush wheel.
[0008] As shown in Fig. 1, a device 1 for applying a heat-sealing primer 4 on the rim 9 of a glass container 7 usually comprises a coating roller 2, a pressing roller 3, a scraper 5 and a collecting tray 6. Thanks to a pump (not visible in Fig. 1), the heat-sealing primer 4 is poured between the coating roller 2 and the pressing roller 3 which rotate each other in an opposite direction. More precisely, the heat-sealing primer 4 is evenly distributed by the pressing roller 3 that exerts a pressure on the coating roller 2. There will also be an accumulation of product called a "bead" at the junction between the coating roller 2 and the pressing roller 3, which serves as an in-situ primer reservoir. The excess of heat-sealing primer 4 is poured in the collecting tray 6 thanks to the scraper 5. When the glass container 7, which moves on a conveying apparatus 8 according to the direction shown by the horizontal arrow, comes into contact with the coating roller 2, a determined amount of the heat-sealing primer 4 is applied on the rim 9 of the glass container 7. The conveying apparatus 8 and the coating roller 2 are mechanically driven at the same speed.
[0009] Nowadays, the coating rollers which are used for applying a heat-sealing primer on a glass container comprise the following elements: a guide roller (often made of polyvinyl chloride or steel) for rotatably mounting the coating roller about an axle that is rotatably driven by a conventional drive means; a layer of a foam of ethylene propylene diene monomer (hereafter "EPDM") surrounding said guide roller; a tubular warp or weft knit made of a para-aramid fiber (for example Kevlar ®< fiber) surrounding said layer of a foam of EPDM.
[0010] Thus, in the coating rollers of the prior art, the tubular knit applies the heat-sealing primer on the rim of the glass container.
[0011] The heat-sealing primer is a liquid solution which may comprise different compounds.
[0012] The well-known heat-sealing primers may have one of the following compositions: an inorganic primer and a chromium or aluminum or zirconium salts base (aqueous solution); an organic primer with a polyethylene or polypropylene based aqueous alkaline dispersion stabilized by nonionic surfactant.
[0013] The choice of the different compounds of the formulations of heat-sealing primers may evolve with time.
[0014] Recently, it has been observed that with the above-mentioned coating rollers of the prior art, for some formulations of heat-sealing primer, important amounts of foam of heat-sealing primer may occur between the coating roller and the pressing roller. Indeed, as explained above, in a device for applying a heat-sealing primer on the rim of a glass container, said heat-sealing is poured between the coating roller and the pressing roller.
[0015] More precisely, it was found that the tubular knit of the coating roller contributes to the formation of a foam of the heat-sealing primer between the coating roller and the pressing roller. The formation of foam can be explained in view of the specific texture of the tubular knit which may generate some foam when it comes into contact with some compositions of heat-sealing primer. Indeed, when the coating roller and the pressing roller, which are close to each other, rotate in an opposite direction, said coating roller comprising a tubular knit may generate a foam of heat-sealing primer induced by this specific feature of the tubular knit and the frictions between the coating roller and the pressing roller, like a sponge impregnated with a cleaning-product and subjected to some frictions.
[0016] This foam renders the heat-sealing primer totally unusable for applying it on the rim of a glass container. Indeed, the generated foam does not allow the application of a layer of heat-sealing primer on the rim of the container with an appropriate and perfectly homogeneous (i.e. without any aggregates) thickness around the full circumference of said rim.
[0017] Thus, there is a need to overcome this problem of the foam which is generated between the coating roller and the pressing roller.
[0018] The inventors found that a coating roller having specific features which are here below detailed overcomes this problem.
[0019] The present invention is to provide a coating roller for applying a liquid (for example a heat-sealing primer, an adhesion promoter or a varnish) on the rim of a container (preferably a glass container) that prevents the formation of foam between the coating roller and the pressing roller, said coating roller is characterized in that the outer surface of the coating roller is a layer of a polymeric material having a hardness between 5 Sh A and 100 Sh A, preferably between 20 Sh A and 50 Sh A, most preferably between 25 Sh A and 35 Sh A, the hardness being measured in accordance with ISO 868 and ISO 7619 standards and where "Sh A" is the unit of the measurement of the Shore scale testing hardness of the polymeric material.
[0020] Thanks to the selection of the hardness of the polymeric material, the inventors demonstrated that no foam occurs between the coating roller and the pressing roller during the application of a heat-sealing primer on the rim of a glass container. Unlike the tubular knit of para-aramid fiber of the coating rollers of the prior art, the selected polymeric material prevents from the formation of foam regardless of the composition of the heat-sealing primer.
[0021] The polymeric material may be selected in the group consisting of natural rubber, silicone, polyurethane and EPDM.
[0022] Preferably, the polymeric material complies with food regulations. Indeed, the glass container may be intended to contain some food products.
[0023] Most preferably, the polymeric material is natural rubber. Indeed, this material perfectly complies with food regulations.
[0024] The thickness of the layer of the polymeric material may be comprised between 2.5 mm and 50 mm, preferably between 2.5 mm and 20 mm, and most preferably between 2.5 mm and 7.5 mm.
[0025] In preferred embodiments of the invention, the layer of the polymeric material is textured. The texturation of the layer of the polymeric material provides the advantage of allowing the calibration of the amount of the liquid (for example the heat-sealing primer) which is applied on the rim of the glass container. Moreover, the texturation allows to apply a higher amount of the liquid (for example the heat-sealing primer) on the rim of the glass container. It prevents from leaking and spilling of the heat-sealing primer.
[0026] The shape of the texturation of the layer of the polymeric material may be any kind of shape (for examples pyramids, squares, lines).
[0027] In preferred embodiments of the invention, the coating roller has a flexibility comprised between 10 µm / N and 65 µm / N, the flexibility being determined according the following equation (1): Flexibility = L / F wherein "L" is the depth of crushing of the coating roller when a force "F" of 100 N is applied on said coating roller.
[0028] The inventors found that a coating roller having a flexibility comprised between 10 µm / N and 65 µm / N is perfectly appropriate for preventing the risk of splashes on the container and for increasing the mass of liquid (such as heat-sealing primer) which is applied onto the rim of the container.
[0029] In some embodiments of the invention, the coating roller according to the present invention may comprise: a guide roller (preferably made of polyvinyl chloride or steel) for rotatably mounting the coating roller about an axle that is rotatably driven by a conventional drive means; a layer of a foam material surrounding said guide roller; a layer of the above detailed polymeric material surrounding said layer of a foam material.
[0030] In the coating roller according to the invention, the layer of the foam material allows to overcome the possible deviation of parallelism between the rim of the glass container and its bottom. Moreover, the layer of the foam material allows to adapt the coating roller to several kind of glass containers having different heights according to their respective technical specifications.
[0031] The foam material may be a foam of EPDM, silicone, polyurethane, polyethylene or epoxy. Preferably, the foam material is a foam of EPDM.
[0032] In these embodiments of the invention, the diameter of the coating roller may be comprised between 105.2 mm and 800 mm, preferably between 160.5 mm and 465 mm.
[0033] The thickness of the layer of the foam material may be comprised between 0.1 mm and 100 mm, preferably between 0.25 mm and 50 mm, and most preferably between 0.5 mm and 20 mm.
[0034] The layer of the foam material may be glued on the guide roller.
[0035] The layer of the above detailed polymeric material may be glued on the layer of the foam material.
[0036] In these embodiments of the invention, the thickness of the above detailed layer of the polymeric material may be comprised between 2.5 mm and 50 mm, preferably between 2.5 mm and 20 mm, and most preferably between 2.5 mm and 7.5 mm.
[0037] In these embodiments of the invention, the guide roller is a hollow cylinder having: an inner diameter which may be comprised between 10 mm and 80 mm, preferably between 25 mm and 45 mm; an outer diameter which may be comprised between 100 mm and 500 mm, preferably between 155 mm and 325 mm.
[0038] In most preferred embodiments of the invention, the coating roller according to the present invention may comprise: a guide roller (preferably made of polyvinyl chloride or steel) for rotatably mounting the coating roller about an axle that is rotatably driven by a conventional drive means; a no-crush wheel surrounding said guide roller; a layer of the above detailed polymeric material surrounding said no-crush wheel.
[0039] Fig. 2 shows a perspective view of an example of a no-crush wheel 10 which has: a rim 11; soft spokes 12 that give flexibility and resiliency to the rim 11.
[0040] The length of the soft spokes may be comprised between 10 mm and 130 mm, preferably between 30 mm and 100 mm and most preferably between 50 mm and 80 mm.
[0041] The no-crush wheel comprises multiple voids which gives flexibility and resiliency.
[0042] The outer diameter of the no-crush wheel (i.e. the dotted arrow referenced as "d2" in Fig. 2) may be comprised between 100 mm and 500 mm, preferably between 175 mm and 325 mm.
[0043] The inner diameter of the no-crush wheel (i.e. the arrow referenced as "d1" in Fig. 2) may be comprised between 10 mm and 80 mm, preferably between 25 mm and 60 mm.
[0044] The inner diameter d1 of the no-crush wheel corresponds to the outer diameter of the guide roller.
[0045] The no-crush wheel may be made of a malleable material.
[0046] The no-crush wheel may be made of a material selected in the group consisting of polyurethane, polyvinyl chloride, silicone, rubber or polyamide.
[0047] The no-crush wheel may be glued on the guide roller.
[0048] The layer of the above detailed polymeric material may be glued on the no-crush wheel.
[0049] It is well-known to use no-crush wheel in the technical field of packaging production, in particular for the production of cardboard during the step of folding. More precisely, it is known to use no-crush as a transfer element in a device for folding cardboard. The no-crush wheel can press cartons without causing physical damage or visual marking.
[0050] Thus, the present invention discloses a novel use of a no-crush wheel.
[0051] As the layer of the foam material, the no-crush wheel allows to : overcome the possible deviation of parallelism between the rim of the glass container and its bottom; overcome the possible deviation of flatness of the rim of the glass container; adapt the coating roller to several kind of glass containers having different heights according to their respective technical specifications.
[0052] The no-crush wheel is more flexible than the layer of the foam material (for example a foam of EPDM).
[0053] Moreover, the no-crush provides the advantage of avoiding liquid splashes.
[0054] In these most preferred embodiments of the invention, the diameter of the coating roller may be comprised between 105 mm and 600 mm, preferably between 180 mm and 365 mm.
[0055] In these most preferred embodiments of the invention, the thickness of the above detailed layer of the polymeric material may be comprised between 2.5 mm and 50 mm, preferably between 2.5 mm and 20 mm, and most preferably between 2.5 mm and 7.5 mm.
[0056] In these most preferred embodiments of the invention, the guide roller is a hollow cylinder having : an inner diameter which may be comprised between 5 mm and 75 mm, preferably between 25 mm and 45 mm ; an outer diameter which may be comprised between 10 mm and 80 mm, preferably between 25 mm and 60 mm.
[0057] The present invention is to provide a method for applying a liquid to a rim of a container (preferably a glass container), the method comprising contacting the rim of the container with a coating roller according to the invention comprising the liquid, thereby transferring the liquid to the rim of the container.
[0058] The liquid may be a heat-sealing primer or an adhesion promoter or a varnish.
[0059] The liquid is preferably a heat-sealing primer.
[0060] The container (preferably the glass container) may be selected in the group consisting of a jar, a bottle, a flask and a decanter.EXPERIMENTAL PART:
[0061] 3 different coating rollers according to the present were tested.
[0062] The first coating roller according to the invention comprised: a guide roller made of polyvinyl chloride for rotatably mounting the coating roller about an axle that is rotatably driven by a conventional drive means; a layer of a foam of EPDM surrounding said guide roller; a layer of silicone having a hardness of 24 Sh A (measured in accordance with ISO 868 and ISO 7619 standards) with macroscopic roughness and which was glued on said layer of foam of EPMD by surrounding it.
[0063] The second coating roller according to the invention comprised: a guide made of polyvinyl chloride for rotatably mounting the coating roller about an axle that is rotatably driven by a conventional drive means; a no-crush wheel surrounding said guide roller; a layer of natural rubber having a hardness of 30 Sh A (measured in accordance with ISO 868 and ISO 7619 standards) with macroscopic roughness and which was glued on said no-crush wheel.
[0064] The third coating roller according to the invention comprised: a guide made of polyvinyl chloride for rotatably mounting the coating roller about an axle that is rotatably driven by a conventional drive means; a no-crush wheel surrounding said guide roller; a layer of natural rubber having a hardness of 30 Sh A (measured in accordance with ISO 868 and ISO 7619 standards) with microscopic roughness and which was glued on said no-crush wheel.
[0065] By using them in a standard device for applying a heat-sealing primer on the rim of a glass container as above detailed, the 3 coating rollers according to the invention complied with the following requirements: absence of foam and projections between the coating roller and the pressing roller; absence of solidification of the heat-sealing primer; homogeneity of the coating of the heat-sealing primer on the rim of the glass container.
Claims
1. A coating roller (2) for applying a liquid (4) on the rim (9) of a container (7), preferably a glass container, characterized in that the outer surface of the coating roller (2) is a layer of a polymeric material having a hardness between 5 Sh A and 100 Sh A, preferably between 20 Sh A and 50 Sh A, the hardness being measured in accordance with ISO 868 and ISO 7619 standards.
2. A coating roller (2) according to claim 1, characterized in that the polymeric material is selected in the group consisting of natural rubber, silicone, polyurethane and ethylene propylene diene monomer (EPDM).
3. A coating roller (2) according to claim 2, characterized in that the polymeric material is natural rubber.
4. A coating roller (2) according to any one of claims 1 to 3, characterized in that the thickness of the layer of the polymeric material is comprised between 2.5 mm and 50 mm, preferably between 2.5 mm and 20 mm.
5. A coating roller (2) according to any one of claims 1 to 4, characterized in that the polymeric material is textured.
6. A coating roller (2) according to any one of claims 1 to 5, characterized in that the coating roller comprises: - a guide roller, preferably made of polyvinyl chloride or steel, for rotatably mounting the coating roller about an axle that is rotatably driven by a conventional drive means; - a layer of a foam material surrounding said guide roller; - a layer of the polymeric material surrounding said layer of a foam material.
7. A coating roller (2) according to claim 6, characterized in that the foam material is a foam of EPDM, silicone, polyurethane, polyethylene or epoxy.
8. A coating roller (2) according to claim 6 or claim 7, characterized in that the thickness of the layer of the foam material is comprised between 0.1 mm and 100 mm, preferably between 0.25 mm and 50 mm.
9. A coating roller (2) according to any one of claims 1 to 5, characterized in that the coating roller comprises: - a guide roller, preferably made of polyvinyl chloride or steel, for rotatably mounting the coating roller about an axle that is rotatably driven by a conventional drive means; - a no-crush wheel (10) surrounding said guide roller; - a layer of the polymeric material surrounding said no-crush wheel.
10. The coating roller (2) of claim 9, characterized in that the no-crush wheel (10) is made of a material selected in the group consisting of polyurethane, polyvinyl chloride, silicone, rubber or polyamide.
11. A coating roller (2) according to any one of claims 1 to 10, characterized in that the flexibility of the coating roller (2) is comprised between 10 µm / N and 65 µm / N, the flexibility being determined according the following equation (1): Flexibility = L / F wherein "L" is the depth of crushing of the coating roller when a force "F" of 100 N is applied on said coating roller (2).
12. A method for applying a liquid (4) to a rim (9) of a container (7), preferably a glass container, the method comprising contacting the rim (9) of the container (7) with a coating roller (2) according to any one of claims 1 to 11 comprising the liquid (4), thereby transferring the liquid to the rim (9) of the container (7).
13. The method for applying a liquid to a rim (9) of a container (7) according to claim 12, characterized in that the liquid is a heat-sealing primer (4) or an adhesion promoter or a varnish.
14. The method for applying a liquid (4) to a rim (9) of a container (7) according to claim 12 or 13, characterized in that the container (7) is selected in the group consisting of a jar, a bottle, a flask and a decanter.