EP1755804A1

EP1755804A1 - Method for making decorated bottle caps with improved mechanical strength and device for implementing said method

Info

Publication number: EP1755804A1
Application number: EP05763703A
Authority: EP
Inventors: Jean De Guerry; Raymond Guicheney
Original assignee: Alcan Packaging Capsules SAS
Current assignee: Amcor Flexibles Capsules France SAS
Priority date: 2004-05-06
Filing date: 2005-05-02
Publication date: 2007-02-28
Anticipated expiration: 2025-05-02
Also published as: DE602005004783D1; FR2869820B1; DE602005004783T2; CA2564640A1; EP1755804B1; AU2005251969B2; AU2005251969A1; ZA200609232B; PL1755804T3; CA2564640C; MXPA06012814A; US20070107190A1; WO2005120743A1; ATE385864T1; FR2869820A1; US7832075B2; NZ550928A; ES2301034T3

Abstract

A method comprising: a) providing sheet or format metal; b) swaging said metal by means of a swaging lubricant, so as to form a swaged blank; c) degreasing said swaged blank, so as to typically remove the remains of the swaging lubricant, to form a degreased blank capable of being lacquer coated; d) lacquer coating said degreased blank, said resulting lacquer coated blank being then optionally decorated; e) an optional finishing step. The method is characterized in that during the degreasing at step c), said swaged blank is subjected to an energetic radiation emission treatment of selected intensity and duration to eliminate or decompose said remains of lubricant, said treatment being wholly carried out at a metal temperature less than 150 degree C., and for a duration typically less than 1 second, so as to obtain, following said treatment, a surface tension not less than 34 dynes/cm.

Description

PROCESS FOR MANUFACTURING DECORATED CAPSULES WITH IMPROVED MECHANICAL RESISTANCE

FIELD OF THE INVENTION

The invention relates to the field of closure capsules or overcap capsules, and typically metal capsules based on aluminum or tin. The invention relates more particularly to a method of manufacturing these capsules.

STATE OF THE ART

Metal corking caps, typically made of aluminum, are typically manufactured as follows:

a stamping press forms blanks of capsules made from varnished strip metal on its two faces, with a typical thickness ranging from 0.21 to 0.25 mm,

these blanks are degreased in an oven at a high temperature, typically from 180 ° to 210 ° C., for a time ranging from 3 to 5 minutes, in order to eliminate the drawing lubricant,

- These blanks are then lacquered on their entire outer surface and are passed in an oven to cook the lacquer,

these lacquered blanks are printed on the skirt, typically in offset, with a final drying of the inks in an oven, an overprint varnish is finally applied to the printing in order to protect it, said varnish being dried during a transition to oven

the blank thus obtained is provided with a seal and / or a threaded internal plastic insert.

PROBLEMS POSED Regarding metal caps, whether capping or overcapping, there is a permanent demand both to reduce production costs, under penalty of seeing these capsules replaced by other capsules more economical under the same conditions. 'another technology and another material, and to improve the sets and their wear of use. The invention aims to solve both problems simultaneously.

DESCRIPTION OF THE INVENTION

According to the invention, the method of manufacturing metal capsules, typically made of aluminum, comprises: a) a supply of metal in strips or in format, typically coated on both sides with a layer of stamping varnish, b) a step of stamping, in one or more passes, said metal strip or format, typically using a stamping lubricant, so as to form a stamped blank comprising a head and a skirt, typically axi-symmetric in an axial direction (10), c) a degreasing step of said stamped blank, intended to typically eliminate the residues of stamping lubricant, to form a defatted preform to be lacquered, d) a step of lacquering said blank degreased, said lacquered blank thus obtained being then optionally decorated, e) a possible finishing step, and is characterized in that, during said degreasing step c), said blank blank ie is subjected to a treatment of emission of an energetic radiation chosen in intensity and duration to eliminate or degrade said residues of lubricant, said treatment being carried out entirely with a metal temperature lower than 150 ° C, and for a time typically less than 1 s, so as to obtain, after said treatment, a surface tension at least equal to 33 dynes / cm, and typically at least 34 dynes / cm. Generally, on the one hand, said treatment is carried out at ambient temperature, which is extremely advantageous both with regard to energy savings and with regard to the disadvantages of softening the metal, and other on the other hand, it is realized in masked time insofar as it can be implemented while being associated with all or part of a decoration step, and this without slowing down the rate of said decorating step, so that said step of degreasing is not in itself a step, so it is a very economical implementation operation.

DESCRIPTION OF THE FIGURES

Figure la is a perspective view schematically showing a device for implementing the method according to the invention. FIG. 1b is an axial sectional view of an electrode used in the method according to the invention.

FIGS. 2a and 2b schematically and partially illustrate the degreasing station (53) of the skirt (12) of the blank (1) of FIG. Figure 2a is a section along the axis of rotation (530) of the support (53 ') of the blank (1). Figure 2b is a section in a plane perpendicular to the axis of rotation (530).

Figures 3a and 3b schematically and partially illustrate the station (52) for degreasing the head (11) of the blank (1) of Figure la. Figure 3a is a section along the axis of rotation (520) of the support (52 ') of the blank (1).

Figure 3b is a top view of the head (11), the electrode (40, 40 ') having been shown in dashed lines.

In FIGS. 2a to 3b, the arrows between the electrodes (40, 40 ', 40 ") and the blank (1) represent the plasma (58) formed, the distance d between the electrodes and the blank having been exaggerated by to be able to represent the plasma (58). DETAILED DESCRIPTION OF THE INVENTION

According to the invention, said energy radiation treatment may be a treatment comprising the formation of a plasma or an ionic or electronic efflux.

Said treatment may be a treatment typically using a high electric field, typically at least 5 kV, and a high frequency current, typically at least 10 kHz. Preferably, and as illustrated in FIG. 1a, said treatment can be carried out using two strips or electrodes (40) for transmitting said corona, a lateral electrode (40 "), typically parallel to said skirt (12) , intended to reach and process said skirt (12), and a front electrode (40 '), substantially perpendicular to said lateral electrode (40 ") and parallel to said head (11), for reaching and treating said head (11) ). As illustrated in FIG. 1b, said electrodes (40, 40 ', 40 ") may comprise an electrically conductive metal core (41) covered with a dielectric ceramic layer (42).

It has been found that this type of electrode (40) is particularly adapted to treat the outer metal surface of the stamped blanks (1), to remove its residues of shaping lubricant, and then to allow the attachment of a lacquer.

The Applicant has been able to observe that the treatment according to the invention, both under high voltage and at a high frequency, carried out at ambient temperature and at ambient air, was both economical with the low energy consumed, the installed power being about 500 W, reliable, not very dangerous in its implementation, and not very aggressive for the metal because, with the electrodes used, the emission emitted is regularly distributed over the whole length of the electrode in view of the capsule (1), so that there is no risk of "breakdown" with a point of passage of a localized current that could punctually damage said blank (1). Typically, said treatment can be performed by virtue of a potential difference between said electrodes (40, 40 ', 40 ") and said stamped blank (1), typically ranging from 10 at 30 kV, so as to form said high electric field, said electrodes (40, 40 ', 40 ") being brought to a potential of 10-30 kV and said blank (1) being grounded or at a zero potential, said potential difference serving to regulate said intensity of said treatment, said electrodes (40, 40 ', 40 ") being at a distance d from the surfaces of said blank (1) to be treated less than 4 mm.

As illustrated in FIG. 1a and in FIG. 2a, said lateral electrode (40 ") can be arranged parallel to a generatrix of said skirt (12), so that, by rotation of said blank (1), the entire said skirt (12) is subjected to the energy radiation emitted by said lateral electrode (40 "), in a constant manner over the entire height of said skirt (12).

Said rotation of said blank (1) can extend over 1 to 2 turns, for a time at most equal to 1 second, said blank rotating on itself, having been placed on an arm or stud (52 ', 53' ) rotating on itself along an axis of rotation (520, 530).

According to the invention, said treatment can also be a so-called "cold" plasma treatment, typically carried out at atmospheric pressure.

It is indeed advantageous that the treatment can be carried out at ambient temperature, typically on the run, and without requiring a particular gaseous atmosphere, so as to limit investment costs and operating costs.

Said lubricant may comprise a volatile organic solvent and a lubricating compound capable of rapidly degrading under the action of said treatment. Said compound may be a paraffin oil.

As illustrated in FIG. 1a, said lacquering step may comprise a so-called spraying step in which the entire surface of said degreased blank is spray-covered or lacquered by spraying or spray application, so as to form a lacquered blank (3). Said spraying step may be followed by a first so-called "dust-off" drying, at a temperature below 100 ° C., and typically at a temperature of 80 ° C, for a time typically less than 2 minutes, so that said lacquered blank (3) can then be directly decorated or printed. Between said degreasing step and said spraying step, a time Δt shorter than 15 minutes, typically less than one minute, and possibly less than 10 seconds, may have elapsed.

According to the invention, said lacquered blank (3) can be printed, typically by screen printing but possibly by offset or flexography, on its skirt (12) and possibly on the head (11), then subjected to a second drying, typically at a temperature of 140 ° C, for a time typically less than four minutes, so as to obtain a printed capsule.

Advantageously, to increase the richness of the decor of the final capsule, a raised pattern can be formed on said head (11) of said blank (1, 2, 3) or said printed capsule, said relief pattern being typically formed in using a punch and die set bearing said pattern.

Said strip or format metal may be aluminum, typically of the 8000 series, in a state typically ranging from the 1/4 hard state to a 3/4 hard state, and at a thickness of 0 , 18 mm to 0.30 mm, and preferably from 0.21 mm to 0.25 mm.

Said finishing step may include, typically in the case where said capsule is a closure cap, at least one of the following complementary means:

the incorporation of a seal, the incorporation of a screwing insert,

- The formation of means for facilitating a first opening, typically comprising at least one weakening line.

As illustrated in FIGS. 1b, 2a to 3b, said electrode (40, 40 ', 40 ") can be a cylindrical electrode with an outside diameter typically ranging from 15 mm to 20 mm, and length ranging from 100 to 150 mm. with a metal core (41) of length 50 to 90 mm, said electrode (40, 40 ', 40 ") comprising an outer sheath or layer of dielectric ceramic (42) having a thickness of 0.5 to 3 mm.

According to the invention, said electrode (40, 40 ', 40 ") can be placed at said distance d from said blank (1), that is to say, either of said head (11), or of a generatrix of said skirt (12), said distance d ranging from 0.2 to 4 mm, and typically from 1 mm to 2 mm The tests were generally carried out with d = 1.5 mm.

Another object of the invention is formed by capping capsules formed by the process according to the invention.

Another object of the invention is formed by overcap capsules formed by the process according to the invention.

Another object of the invention is constituted by a use of the process according to the invention for forming capping capsules or caps for overcoupling.

Another object of the invention is formed by a device (5) for implementing, continuously, the degreasing process of blanks (1) according to the invention. As illustrated in FIG. 1a, this device (5) can comprise a mobile support for said blanks, typically a plate (50) rotating about an axis of rotation (50), typically step by step, and provided with a plurality of stations. or stations with levitation means or arms (51 ', 52', 53 ', 54', 55 ') of said blanks (1), said plurality of stations or stations comprising:

a loading station (51) downstream of a feeder (8) made of blanks (1) to be degreased,

- a degreasing station (51, 52) of said blanks (1), said blanks (1) being rotated on themselves facing fixed degreasing electrodes (40, 40 ', 40 ") at a distance d predetermined, said electrodes (40, 40 ', 40 ") being supplied with a current of predetermined frequency and voltage capable of generating a destructive emanation of the residues or residues of lubricant, said blanks (1) being grounded, so as to obtain stamped and degreased blanks (2), an ejection or unloading station (56) of said degreased blanks (2).

Said degreasing station may comprise two treatment stations, a first station (51) for treating said head (11) of said preform (1) to be degreased (1) and a second station (52) for treating said skirt (12). ) with typically a separate treatment of said head (11) and said skirt (12) of said blank (1) to degrease (1). Said plurality of stations or stations further comprises, after said degreasing station or said degreasing stations, a lacquering station (54) and a drying station (55).

EXAMPLE OF REALIZATION

The continuous processing device (5) according to FIGS. 1a and 1b has been developed. Upstream, this device was fed, at the station (51), blanks (1) such as outputs of the stamping press. These stamped blanks (1) were formed from aluminum strip varnished on both sides, the stamping having been made with a lubricant forming a solution of a mineral oil in an alcoholic medium.

The degreasing treatment was carried out either with STT (type SG2) fixed frequency (40 kHz) and variable power from 0 to 715 W, or with a Softal (type 3003) device with a variable frequency between 16 kHz and 40 kHz, and 4 power positions (366 W, 426 W, 493 W and 500). The STT device was used at 50% of its power, ie 350W, while the Softal device was used with a power of 500 W.

An electrode (40, 40 ', 40 ") with a useful length of 70 mm was used, as illustrated in FIG.

The degreasing device (4) comprises, as illustrated in FIG. 1a, a high-voltage, high-frequency current generator (44), a fixed support (45) for the electrodes (40), and the electrodes (40 ', 40). ") arranged so that at each fraction of a turn or not the turntable (50), a blank (1) is positioned at the distance d of the electrodes.

Typically, the degreasing treatment time was 0.55 seconds, the blank (1) making from 1 to 2 turns on itself. In these tests, the distance d was set at 1.5 mm.

As illustrated in FIGS. 2a to 3b, a plasma (58) is formed on the surface of the blank (1) to be treated, and this at room temperature and ambient air. Such a plasma can be observed visually laterally by the presence of a light emission forming a homogeneous blue layer covering the treated metal surface. The blanks (1) are placed on studs (51 ', 52', 53 ', 54', 55 ', 56') rotating on themselves at certain stations (52, 53, 54, 55) about axis rotation (520, 530, 540, 550). Taking into account the experimental parameters, it was calculated that the electrical energy received by the blanks (1) amounted to 7.8 J / cm ² with the STT device and 4 J / cm 2 with the Softal device.

Downstream of this device (5), the degreased and lacquered blanks (3) ejected from the station

(55), were directed to a screen printing machine, so as to obtain printed capsules.

Downstream of this device (5), the blanks have also been subjected to different types of finishing: formation of a relief, typically on the head (11), but possibly on the skirt (12) of the blank (2, 3) or the final capsule, or formation of means for facilitating a first opening, means comprising at least one weakening line.

This device (6) has been used to manufacture caps and caps closure caps closure caps having a seal or a threaded insert.

Results of the tests:

On the defatted blanks (2), the surface tension was measured and observed that it ranged from 34 dynes / cm to 36 dynes / cm, the starting blanks (1) having a surface tension ranging from 30 to 32 dynes / cm. Lacquered blanks (3) were subjected to abrasion tests and tear-off tests on adhesive tape.

All these tests showed the excellent adhesion of the lacquer on the degreased metal according to the invention.

ADVANTAGES OF THE INVENTION

The invention has great advantages. Indeed, firstly, the method according to the invention avoids expensive treatments in investment and operating costs, particularly with regard to the energy consumed.

On the other hand, this method avoids any adoûcissëme fù ^~ metaf constituting the initial metal blank and any loss of its mechanical characteristics. In view of this, it has thus been possible to reduce the thickness of the metal blank by 5 to 10%.

Finally, the invention makes it possible to avoid bulky equipment, so that the treatment according to the invention corresponds to both an investment cost, and to a minimal occupied volume, which makes it possible to have a very large production workshop. compact, besides said processing can be performed in masked time and continuously, so that it does not introduce specific production costs, the cost of energy consumed being negligible.

LIST OF REFERENCES

Degreased draft to degrease 1 Axial direction 10 Head 11 Skirt 12 Degreased stamped roughing 2

Degreased and lacquered roughing 3 Degreasing treatment device 4

Barrette or emission electrode 40

Front electrode - parallel bar at 11 40 '

Side electrode - parallel bar at 12 40 "Metallic shaft 41

Dielectric ceramic sheath 42

Power supply cable 43

High Voltage & High Frequency Generator 44

Electrode holder 40, 40 ', 40 "45 Processing device 5 Turning tray stepping 50 Axis of rotation 500 Station or loading station of 1 51 Plot support of 1 51' Station or processing station of 11 52 Plot support of 1 52 'Rotating axis 520 Substation or processing station 12 53 Plot bearing 1 53' Rotating axis 530 Substation or lacquering station 2 54 Plot bearing 2 54 'Rotating axis 540 Substation or drying station 55 Plot support 2 55 'Rotation axis 550 Station or ejection station 3 56 Plot support 3 56' Ground 57 Plasma 58

Lacquering device 6 Spray nozzle 60 Feed pipe 61

Drying device 7

Blank feed device (1) 8

Transfer device (to print line) 9

Claims

1. A method of manufacturing metal caps, typically aluminum, comprising: a) a supply of metal strip or format, typically coated on both sides with a layer of stamping lacquer, b) a stamping step in one or more passes of said strip or size metal, typically with a drawing lubricant, to form a stamped blank (1) comprising a head (11) and a skirt (12) typically axi-symmetrical in an axial direction (10), c) a degreasing step of said stamped blank (1), intended to typically remove the residues of stamping lubricant, to form a degreased blank

(2) suitable for being lacquered, d) a step of lacquering said degreased blank (2), said lacquered blank (3) thus obtained being then optionally decorated, e) a possible finishing step, characterized in that, during said step c) of degreasing, said stamped blank (1) is subjected to a treatment of emission of energy radiation chosen in intensity and duration to eliminate or degrade said lubricant residues, said treatment being made entirely with a metal temperature less than 150 ° C, and for a time typically less than 1 s, so as to obtain, after said treatment, a surface tension at least equal to 33 dynes / cm, and typically at least 34 dynes / cm.

2. The method of claim 1 wherein said energy radiation treatment is a treatment comprising the formation of a plasma or an ionic or electronic efflux.

3. Method according to claim 2 wherein said treatment is a treatment typically using a high electric field, typically at least 5 kV, and a high frequency current, typically at least 10 kHz.

4. The method of claim 3 wherein said treatment is performed using two bars or electrodes (40) for transmitting said corona, a lateral electrode (40 "), typically parallel to said skirt (12), for reaching and treating said skirt (12), and a front electrode (40 '), substantially perpendicular to said lateral electrode (40 ") and parallel to said head (11), for reaching and treating said head (11).

The method of claim 4 wherein said electrodes (40, 40 ', 40 ") comprise an electrically conductive metallic core (41) covered with a dielectric ceramic layer (42).

6. Method according to any one of claims 4 to 5 wherein said treatment is performed through a potential difference between said electrodes (40 ^~ 40 ^r , 40 ") èf said stamped blank (1), typically ranging from 10 to 30 kV to form said high electric field, said electrodes (40, 40 ', 40 ") being brought to a potential of 10-30 kV and said blank (1) being grounded or at zero potential, said difference in potential for regulating said intensity of said treatment, said electrodes (40, 40 ', 40 ") being at a distance from the surfaces of said blank (1) to be treated less than 4 mm.

7. The method of claim 6 wherein said lateral electrode (40 ") is disposed parallel to a generatrix of said skirt (12), so that by rotation of said blank (1), all of said skirt (12) ) is subjected to the energy radiation emitted by said lateral electrode (40 "), in a constant manner over the entire height of said june (12).

8. The method of claim 7 wherein said rotation of said blank (1) extends over 1 to 2 revolutions, for a time at most equal to 1 second.

9. The method of claim 1 wherein said treatment is a so-called "cold" plasma treatment, typically carried out at atmospheric pressure.

The process of any one of claims 1 to 8 wherein said lubricant comprises a volatile organic solvent and a lubricating compound capable of rapidly degrading under the action of said treatment.

The method of claim 10 wherein said compound is a paraffin oil.

12. Method according to any one of claims 1 to 11 wherein said lacquering step comprises a so-called spraying step in which typically covers the entire outer surface of said degreased blank, a lacquer spray or spray application , so as to form a lacquered blank (3).

13. The method of claim 12 wherein said step of spraying is followed by a first drying called "dusting", at a temperature below 100 ° C, and typically at a temperature of 80 ° C, for a time typically less than 2 minutes, so that said lacquered blank (3) can then be directly decorated or printed.

14. A method according to any one of claims 12 to 13 wherein between said degreasing step and said spraying step has elapsed a time Δt less than 15 minutes, typically less than one minute, and possibly less than 10 seconds.

15. Method according to any one of claims 1 to 14 wherein said lacquered blank (3) is printed, typically by screen printing, on its skirt (12) and optionally on the head (11), then subjected to a second drying, typically at a temperature of 140 ° C, for a time typically less than four minutes, so as to obtain a printed capsule.

16. The method according to any one of claims 1 to 15 wherein a raised pattern is formed on said head (11) of said blank (1, 2, 3) or said capsule printed, said relief pattern being typically formed using a set of punch and die carrying said pattern.

The method of any one of claims 1 to 16 wherein said strip or format metal is aluminum, typically from the 8000 series, to a state typically ranging from 1/4 hard state to a state 3/4 hard, and at a thickness ranging from 0.18 mm to 0.30 mm, and preferably from 0.21 mm to 0.25 mm.

18. Method according to any one of claims 1 to 17 wherein said finishing step comprises in particular, typically in the case where said capsule is a closure cap, at least one of the following complementary means:

the incorporation of a seal,

- The incorporation of a screw insert, ^{"~" ~}

The method of any one of claims 4 to 18 wherein said electrode (40, 40 ', 40 ") is a cylindrical electrode with an outside diameter typically ranging from 15 mm to 20 mm, and ranging in length from 100 to 150. mm, with a metal core (41) of length ranging from 50 to 90 mm, said electrode (40, 40 ', 40 ") comprising a sheath or outer layer of dielectric ceramic (42) having a thickness of 0.5 at 3 mm.

20. A method according to any one of claims 1 to 19 wherein said electrode (40, 40 ', 40 ") is placed at a distance d from said blank (1), that is to say, either of said head ( 11), or a generatrix of said skirt (12), said distance d ranging from 0.2 to 4 mm, and typically from 1 mm to 2 mm.

21. Use of the method according to any one of claims 1 to 20 to form capping capsules or caps for overcoupling.

22. Device (5) for implementing, continuously, the degreasing process of blanks (1) according to any one of claims 1 to 20 comprising a movable support for said blanks, typically a plate (50) rotating along an axis rotation device (50), typically stepwise, and provided with a plurality of stations or stations with levitation means or arms (51 ', 52', 53 ', 54', 55 ') of said blanks (1), said plurality comprising:

- a degreasing station (51, 52) of said blanks (1), said blanks (1) being rotated on themselves opposite fixed degreasing electrodes (40, 40 ',

40 ") at a predetermined distance d, said electrodes (40, 40 ', 40") being supplied with a current of predetermined frequency and voltage capable of generating a destructive emanation of the residues or residues of lubricant, said blanks (1) being to the ground, so as to obtain stamped and degreased blanks (2), - an ejection or unloading station (56) of said degreased blanks (2).

Apparatus according to claim 22 wherein said degreasing station comprises two treatment stations, a first station (51) for treating said head (11) of said preform (1) to be degreased (1) and a second station (52) for treating said skirt (12) with typically separate treatment of said head (11) and said skirt (12) of said preform (1) to be degreased (1).

24 Apparatus according to any one of claims 22 to 23 wherein said plurality further comprises, after said degreasing station or said degreasing stations, a lacquering station (54) and a drying station (55).