FR2817175A1 - Method of spray painting small packaging capsules uses spray nozzle with slot shaped outlet to project line of paint onto capsule - Google Patents

Abstract

The method of spray painting uses a single to spray nozzle (2) to project the paint. The nozzle has a slot shaped outlet with a length (Fl) much greater than the maximum width f the pair flow, to form a laminar flow which projects the paint onto the surface in a line. The spray nozzle is positioned so that the paint line extends over the whole of the generatrix (G) of the surface. An Independent claim is also included for a package made using the method

Description

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METHOD FOR LAMINATING SMALL DIMENSION PACKAGING ELEMENTS SUCH AS CAPSULES
FIELD OF THE INVENTION The invention relates to the field of lacquering small packaging elements such as capsules, and more particularly the lacquering of metal capsules, typically aluminum, tin, complex or polymer.

STATE OF THE ART The capsules, in particular the metal overcaping capsules made of aluminum, are manufactured by stamping or stamping and drawing of metal blanks followed by annealing of the aluminum, then decorated, and finally subjected to a heat treatment of decor The decoration consists of exterior lacquering, then the impression of a decoration or various indications.

As regards the step of lacquering the capsules, it is carried out using four lacquering heads, two of which are movable parallel to the longitudinal axis of the capsules, and two in stationary position and facing the capsule placed on a support rotating on itself: a first head sending a lacquer cone on the head of the capsule, two other heads each sending a cone of lacquer on the skirt of the capsule, and a fourth head ensuring the connection between the lacquer deposited on the head and lacquer deposited on the skirt.

Each head is constituted by a nozzle nozzle with a circular orifice, nozzle through which is projected the lacquer driven by compressed air in a cone of lacquer dispersed or micronized in pressurized air serving as a propellant.

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PROBLEMS POSED The problems posed by the nozzle guns used are of several types: on the one hand, the lacquering installation is complex, given the presence of four lacquering heads per lacquering station. This complexity is reflected both by a high initial investment, especially in view of the lacquers fog collection facilities, also by high maintenance costs, and also by high labor costs for the adjustment, monitoring the proper functioning of these heads and cleaning the lacquer installation.

 - On the other hand, the yield of lacquer deposited on the capsule is low, much less than 50%, this yield being defined by the ratio of the amount of lacquer actually deposited on the capsule / amount of spray applied. The consequences are twofold: in the first place, the material cost in lacquer consumed is very high in view of the losses, and secondly, very large quantities of lacquer are projected and deposited elsewhere than on the capsule, which results in high costs to first clean the lacquering stations, to recover these residues of lacquer and then to eliminate them.

- Finally, the capsules lacquered according to this process may have quality problems, the technique of compressed air projection does not sometimes exclude the clogging of a nozzle and thus leading to an uneven lacquer thickness from one end to the other. other of the capsule.

The invention aims to solve all of these problems.

DESCRIPTION OF THE INVENTION According to the invention, the method of lacquering the surface of a packaging element, non-planar, of small dimension, and having an axis of symmetry, typically of a capsule or a cap, metal, metalloplastic or polymer, formed of a head and a skirt, comprises the projection under pressure, thanks to at least one nozzle typically mounted on a lacquering gun, a lacquer flow on the surface of said element d packaging for forming a lacquer layer, said nozzle and said packaging member

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étant en mouvement relatif soit de rotation d'au moins un tour ou 3600 selon ledit axe de symétrie, soit de translation selon la longueur dudit élément ou de ladite surface à laquer, puis le séchage éventuel de ladite couche de laque, de manière à recouvrir la totalité de la surface dudit élément à laquer, et est caractérisé en ce que : a) on utilise une seule buse projetant un flux de laque sur ladite surface, ladite surface étant une surface intérieure ou extérieure, b) ladite buse présente un orifice en forme de fente, de longueur FL plus grande que sa largeur ou épaisseur maximale FEM, ledit flux de laque projeté formant un flux lamellaire ou un rideau, de manière à ce que ledit flux de laque soit projeté sur ladite surface intérieure ou extérieure à laquer selon une ligne dite de balayage, c) la fente de ladite buse et ledit élément d'emballage sont orientés et positionnés l'un par rapport à l'autre de manière à ce que ladite ligne de balayage s'étende sur la totalité d'une génératrice G de ladite surface à laquer, la totalité de cette surface étant laquée en la balayant par déplacement relatif de ladite buse ou dudit rideau et dudit élément d'emballage.

being in relative motion or rotation of at least one turn or 3600 along said axis of symmetry, or translation along the length of said element or said surface to be lacquered, then the possible drying of said lacquer layer, so as to cover the entire surface of said element to be lacquered, and is characterized in that: a) using a single nozzle projecting a lacquer flow on said surface, said surface being an inner or outer surface, b) said nozzle has an orifice in slot shape, of length FL greater than its width or maximum thickness FEM, said projected lacquer flow forming a lamellar flow or a curtain, so that said lacquer flow is projected onto said inner or outer surface to lacquer according to a so-called scanning line, c) the slot of said nozzle and said packaging element are oriented and positioned relative to each other so that said scanning line is tends over an entire generatrix G of said surface to be coated, all of which surface is lacquered in the scanning by relative movement of said nozzle or of said curtain and of said package member.

This combination of means solves all the problems posed.

Indeed, on the one hand, a single nozzle is sufficient where 4 traditional spray nozzles were used, at least in the case where it is a question of applying a lacquer on the entire external surface of the element of packaging.

On the other hand, it has been verified that this process allows substantial savings in lacquer, consumption being reduced by at least 30%, as well as significant savings in production costs: less cleaning time, less waste , etc ...

Finally, the invention allows a production of constant quality as regards the regularity of thickness and appearance of the deposited lacquer layer.

Overall, it is estimated that the overall cost of lacquering (material, labor, equipment depreciation) will decrease by approximately 20%.

DESCRIPTION OF THE FIGURES

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 All the figures relate to the invention and are axial sections. As a packaging element (1), an over-capping capsule having an axis of symmetry (10) formed of a head (11) and a skirt (12) has been taken.

 Figures 1 to 5 are schematic views, in axial section, illustrating the relative position of the spray nozzle (2) with its axial slot (20) greatly enlarged relative to the capsule (1).

FIG. 1 shows the lacquering of the entire external surface (13), the axial slot (2) being fixed and the capsule (1) placed on a rotating support (6). along the axis of symmetry (10).

Figure 2, similar to Figure 1, differs in that it shows the lacquering of the entire inner surface.

Figures 3 to 5 relate to three methods of lacquering the portion of the inner surface of the capsule corresponding to the opening area (18) of the capsule (1).

In Figure 3, the nozzle (2) comprises an axial slot (20) forming a flow (30), the entire surface to be lacquered being obtained by a relative rotation of a lathe along the axis (10).

In FIG. 4, the nozzle (2) comprises an annular slot (31) of annular profile 8 <5 thus forming a narrow annular flow (31, 310), so that, if said rotation is optional, the relative translation of the Nozzle is required for the stream (310) to sweep the entire opening area (18).

On the other hand, in FIG. 5, the nozzle (2) comprises an annular slot (31) with an annular profile 8 close to 450 eut thereby forming a wide annular flux (31, 31), so that, said rotation being optional, the relative translation Nozzle is no longer needed for the stream (310) to sweep the entire opening area (18).

FIG. 6 schematically illustrates, in the case of FIG. 1, the variation of the angle α, in ordinate, angle formed by the inclination of a flow element (300) on the surface encountered, as a function of a angular coordinate psi, on the abscissa, spotting each

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élément de flux (300), l'angle a étant maximum et noté aM lorsque P,, vaut ssM, c'est- à-dire pour l'élément de flux (301) projeté sur la ligne de jonction (120) de la tête (11) et de la jupe (12), jonction qui forme le sommet d'un angle y égal à 90 . Lorsque cet élément de flux (301) est également la bissectrice de l'angle y, alors il n'y a pas de discontinuité dans l'épaisseur de la fente FE, comme illustré sur la figure 7 où l'épaisseur FE est portée en ordonnée en fonction de l'angle a en abscisse, cet angle

variant dans le cas de la figure 1 entre une valeur minimum ap et une valeur maximum aM.

flow element (300), the angle a being maximum and noted aM when P ,, is ssM, that is to say for the flow element (301) projected on the connecting line (120) of the head (11) and the skirt (12), junction which forms the vertex of an angle y equal to 90. When this flow element (301) is also the bisector of the angle y, then there is no discontinuity in the thickness of the slot FE, as illustrated in FIG. 7 where the thickness FE is carried by ordinate as a function of the angle α on the abscissa, this angle

varying in the case of Figure 1 between a minimum value ap and a maximum value aM.

FIGS. 8a to 11b are diagrammatic illustrations of variants of the method according to the invention, FIGS. 8a, 9a, 10a and 11 diagrammatically the process and FIGS. 8b, 9b, 10b and 11b schematizing the corresponding product obtained.

FIGS. 8a and 8b correspond to the modality of FIG. 1, the scanning line of the flow (3, 30) merging with the generatrix G of the capsule according to rotation R.

FIGS. 9a and 9b correspond to FIG. 4, the generatrix G being in this case the circle which, by its translation T over a distance h parallel to the axis of symmetry (10), will generate the inner surface (14) of height h.

FIGS. 1 Oa and 1 Ob correspond to FIG. 5, and are a variant of FIGS. 9a and 9b, the presence of a nozzle), the neighboring annular profile of 450 being large enough for a translation T to be no longer necessary , an optional rotation R, which may however be advantageous.

FIGS. 11a and 11b correspond to FIG. 3, the line segment of height h being in this case the generator G, of the portion to be lacquered, according to the rotation R, which generator merges with the line of scanning of the stream ( 3.30) emitted by the axial slot (20).

DETAILED DESCRIPTION OF THE INVENTION According to a first process modality according to the invention illustrated in FIGS. 1, 2, 8a and 11a: - said slot is an axial slot (20),

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 said lamellar flow (3) has an angular aperture p less than 120, said lamellar flux (3) has a mean plane comprising said axis of symmetry (10), and projects on the distance Lo separating the extreme points (16, 17) of said generator, so that essentially only the surface (13,14) of said packaging element (1) is covered by a thin layer (130, 140) of said lacquer, - said relative displacement of said nozzle ( 2) and said packaging element (1) is a rotation R of at least one turn, in order to lacquer the entire inner (14) or outer (13) surface of said packaging element (1).

Thus, as said scan line extends over a whole generatrix G of said surface to be lacquered, the lamellar flux (3) sweeps, thanks to the rotation R, the entire surface to be lacquered.

In this embodiment, said lamellar flow (3) is projected on said inner (14) or outer (13) surface with a variable angle α according to the point of impact of said flow on said element, and, consequently, the width or thickness FE of said axial slot (20) varies with said angle α according to a function f (a), just as, consequently, the width or thickness RE of any flow element EF, (300) of the lamellar flow (3) passing through by a slit fraction of thickness FEi, said function f (a) being substantially proportional to 1 / sin a, so as to ensure a lacquer layer (130, 140) of constant thickness whatever the angle a.

Preferably, when said function f (a) has a cusp, which is frequent in particular because said package comprises two parts, typically the head (11) and the skirt (12), connecting along a connecting line ( 120) at an angle y, said nozzle (2) and said packaging member (1) are positioned relative to each other so that the EFM flow element (301) lacquer encountering said junction line (120) is oriented along the bisector of the angle y, and thus, the function f (a) being a continuous function, the variable width FE = f (a) of the slot or also, and therefore has no discontinuity, which is clearly advantageous for the manufacture by machining of said slot (20).

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Comme illustré sur le figure 1, ledit flux lamellaire (3) peut présenter, dans son plan moyen, une ouverture angulaire d'angle P au moins égal à l'angle ssr correspondant à l'angle sous lequel la distance Lo est vue depuis ladite fente (20).

As illustrated in FIG. 1, said lamellar flow (3) may have, in its mean plane, an angular aperture with an angle P at least equal to the angle ssr corresponding to the angle at which the distance Lo is seen from said slot (20).

The difference between the angles PT and ss can be between 1 and 5, so as to guarantee the deposition of said lacquer on all of said surface (13, 14) of said packaging element (1), while limiting the loss. lacquer.

The difference between the angles PT and P must be as small as possible provided that it does not lead to a production defect due to lack of lacquer at the ends of the generator G, at points (16) and (17), so as to to minimize the loss of lacquer.

The form factor FL / FE of the axial slot (20), and consequently that of the section of the laminar flow (3), is at least equal to the form factor of said surface (13, 14) of said packaging element , taken equal to Lo / Eo, Lo and Eo being the distances, respectively axial and radial along said axis, between end points of said surface to be lacquered (13,14), this in particular in order to be sure of not having a loss Lateral lacquer.

The FIFE form factor is at least 3.

It is advantageous, although not obligatory, for said nozzle (2) to be stationary and for said packaging element (1) to be carried by a support (6) rotating about the axis of symmetry (10), as illustrated in FIG. Figure 1.

According to the method of the invention, it is possible to lacquer only all or part of the inner (14) or outer (13) surface of said skirt (12) of said packaging element (1).

It is possible to project said lacquer only on a fraction of the inside of said skirt, typically that which corresponds to an opening zone of said capsule, fraction of cylindrical or frustoconical shape of height h, typically between 5 mm and 50 mm. , so that, in this opening zone, said capsule has a lacquer layer over a height h, said opening zone possibly comprising an easy opening means.

For this purpose, it is possible to implement a first variant of the method according to the invention in which:

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 said slit is an axial slit (20), and projects said lacquer onto the inner surface (14) of said capsule over a height h, said lamellar flux (3) has an angular opening ss less than 120, said relative displacement said nozzle (2) and said packaging element (1) is a rotation R of at least one turn, in order to lacquer the entire inner surface (14) over a height h.

This process variant has been illustrated in FIGS. 3, 11a and 11b. In this case, the inner surface to be lacquered and of height h may be generated by a generator G corresponding to a segment of height h and by a rotation R of a lathe, as illustrated in FIGS. 1a and 11b, FIG. scanning line of lamellar flux merging with this segment of height h.

It is also possible to implement a second variant of the method according to the invention in which: said slot is an annular slot (21), centered with respect to said axis of symmetry or rotation, and forming an annular beam of annular profile 8 typically <5, - said lamellar flow (3) has an angular aperture P of 360, - said relative displacement of said nozzle (2) and said packaging element (1) is a translation T on the distance h parallel to said axis of symmetry (10) to lacquer the entire inner surface (14) to a height h.

This process variant has been illustrated in FIGS. 4, 9a and 9b. In this case, the inner surface to be lacquered and of height h can be generated by a generatrix G forming a circle, in the case of a cylindrical capsule, and a translation T over a distance h parallel to the axis of symmetry ( 10), as illustrated in FIGS. 9a and 9b, the scanning line of the lamellar flux merging with the circle of the generator G.

However, this second variant can have a modality according to which said slot (21) can form an annular beam (ss = 360) of annular profile 8 greater than 50 so that said scanning line is in fact a projection surface. extending on said height h, and thus one can do without any translational movement T. However, it is possible in this case to have a rotational movement

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R, so as to obtain an equalizing effect of the surface of the lacquer layer formed.
According to the invention, it is possible to implement all the modalities and variants of the invention with the axis of symmetry (10) in any position, in particular in a horizontal or vertical position. In the latter case, the packaging element can be oriented with its head up or down.

In the process according to the invention, said projection under lacquer pressure is preferably of the airless type, the lacquer itself being in this case sprayed under pressure, without compressed air.

Whenever a rotational movement of at least one turn is required, said rotational movement may comprise at most 5 turns, and typically 2 to 4 turns, which contributes to forming a lacquer layer of regular thickness and constant.

To implement the airless type projection, said pressure can be kept constant and between 20 and 100 bar, or between 2 and 10 MPa.

According to the invention, the length FL of said axial slot (20) can be typically between 200 μm and 500 μm, and the ratio LO / FL is at least 50, so that said lamellar flow forms an angular sector of angle ss between 20 and 60.

Whatever the method variant of the invention, said spray nozzle (2) can be supplied with thermostatically controlled lacquer and / or air-conditioned, so that said lacquer has a constant viscosity, as illustrated in FIG.

Thus, said lacquer may be maintained, depending on its nature and the desired viscosity, at a temperature of between 30 and 65 ° C. and preferably between 35 and 45 ° C.

According to the invention, said packaging element may be a cap, a closure cap or metal overcap, aluminum or tin, metalloplastic, or polymer.

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Said lacquer may be a basecoat or hook, a wax, or a layer intended to mask the outer surface of said element, and possibly to form the layer on which a decoration will be printed.

 Said lacquer may be an overprint varnish applied to the outer surface of said element previously comprising a decoration or printing, so as to protect said decoration or said printing.

Said lacquer can a varnish applied to the inner surface of said element.

Said lacquer or the interior varnish may be in the form of a solution or an emulsion, aqueous or in a solvent medium, of a thermoplastic or thermosetting material, which leads to the formation of a layer or a film after drying .

Said lacquer may have a viscosity, measured at 35 ° C. and at a shear rate of 103 s -1, of between 0.001 Pa · s and 0.01 Pa · s, and has a solids content of between 20% and 45%.

The method according to the invention applies to small packaging elements, such as capsules, in which the distance Lo between the end points of the generatrix G of said element is between 20 mm and 120 mm.

The applicant has observed that, thanks to the means of the invention, it was possible to solve all the problems posed even with lacquered surfaces of such a small size.

In particular, with this method, the thickness of said lacquer, typically measured along a generatrix of said element, can be in the range EM 0.3. EM, EM being the average thickness of between 5 μm and 35 μm.

Another object of the invention relates to a cap, or a closure cap or over-capping, typically aluminum, coated with lacquer on the entire outer surface, and manufactured according to the method of the invention.

Another object relates to overcaping capsules, typically made of aluminum, coated with lacquer or varnish on an annular portion of its inner surface forming the opening zone of said capsule, of height h typically between 5 and 30mm.

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 These last overcaping capsules can also be coated with lacquer on their entire outer surface, and be manufactured according to the method of the invention.

Another object of the invention relates to the use of the lacquer or varnish projection method of the airless type for applying it to all or part of the outer and / or inner surface of a cap or a closure cap. or over-coating, the lacquer itself, or the varnish, being in this case projected under pressure, without compressed air.

More specifically, the invention relates to the use of this process for lacquering small packaging elements, typically 120 mm in length or height in the case of caps for over-capping for Champagne wines, from 50 to 60 mm length or height for capping or over-capping capsules.

TESTS OF EMBODIMENT FIGS. 1 to 1 lb correspond to embodiments of the invention.

All the tests were carried out on blanks of overcaping capsules made of bare aluminum, in the annealed state, of 50 mm length or height and frustoconical with a diameter of head or skirt top of 29.5 mm. diameter, and a bottom opening aperture diameter of 31 mm, a maximum distance Lo between the end points (16,17) of the generator G of about 65 mm in the process variant according to FIG.

In this process variant, the nozzle was placed at a distance X of 50 mm, and at a height Y of 60 mm, the capsule blank being placed on a rotating mandrel (6) at 2000 rpm.

The lamellar flow (3) had an angular aperture p of about 45, the angle PT corresponding to an angle of about 40.

The lacquer that has been used is a commercial polyamide-based red wax usually used to externally coat the overcap capsules.

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La projection de laque a été réalisée avec une buse du commerce de marque Nordson (R) fonctionnant sous une pression de 4, 3 MPa.

The lacquer spray was performed with a Nordson (R) brand commercial nozzle operating at a pressure of 4.3 MPa.

This nozzle had an axial slot (20) of length FL equal to 500 u. m and maximum width FEM equal to 250! lm. Tests were also carried out with a nozzle for which the length FL was equal to 270 μm and the maximum width FEM was equal to 160 μm.

The tests were carried out at room temperature at 18-20 ° C., with a relative humidity of 70 to 80%.

The lacquering was carried out during 2.3 or 4 turns, each turn corresponding to a lacquering time of 30 ms, and at a deposit of 25 mg of lacquer, the lacquer flow rate is adjusted so that the nominal value of the thickness (or weight per capsule) to achieve corresponds to 3 or 4 rounds.

The blanks of capsules were then dried, the whole outer surface of which was covered with a layer of lacquer, with the following drying cycle: 75 s at 50 ° C., then 75 s at 75 ° C., then 75 ° C. at 95 ° C., finally 75 ° C. at 110OC.

It has been observed that with 3 turns, ie a lacquer projection for 90 ms, a deposit of 70 mg of lacquer was obtained which completely homogeneously covered said capsule blank.

Measurements of thicknesses made at different points of the capsule showed that a low dispersion of the thickness was obtained, with a mean thickness EM equal to 10.8 μm, all values being in EM +/- 0 3. EM.

These tests have confirmed the possibility of reducing the consumption of lacquer by at least 30%.

ADVANTAGES OF THE INVENTION

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L'invention constitue pour l'homme du métier un grand bouleversement dans la mesure où elle va changer considérablement les ateliers ou lignes de laquage, en divisant par quatre le nombre de pistolets et buses de laquage et donc les investissements et les frais de fonctionnement, en réduisant considérablement à la fois les pertes de laque en tant que telles et les dépenses afférentes au nettoyage et au traitement de toute la fraction de laque non déposée sur les capsules.

The invention is for the skilled person a great upheaval in that it will significantly change the workshops or lacquering lines, dividing by four the number of spray guns and nozzles and therefore the investment and operating costs, by considerably reducing both the losses of lacquer as such and the expense of cleaning and treating all the lacquer fraction not deposited on the capsules.

In addition, the method according to the invention makes it possible to ensure a lacquering of constant quality, the thickness of lacquer, its tension and its gloss remaining unchanged over time, which further improves the quality of the capsules compared to those of the state of the art.

Ultimately, the process according to the invention considerably reduces the cost of coating the capsules while improving their quality.

LIST OF NOTES Packing element ......................................... 1 Axis of symmetry ................................................. 10 Head ... .................................................. ......... 11 Skirt 12 Junction line 11 and 12 ........... 120 Outside surface ................. ...................... 13 Thin layer of lacquer or varnish 130 Inner surface ................. ...................... 14 Thin layer of lacquer or varnish. 140 Fraction of interior surface height h .. 15 Layer of lacquer or varnish .............. 150 Extreme points of the generator ............. .. 16, 17 Opening area ....................................... 18 Line of weakening 19 Projection nozzle ........................................... .. 2 Axial slot ............................................. ... 20

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Fente annulaire............................................

Annular slot ............................................

21 Lamellar curtain flow ...................................

3 Flux forming an angle sector ss <120 ...

Flow element ..................................

300 Annular flux (ss = 360) ..........................

31 Narrow ring flow 310 Wide ring flow 311 Lacquer or varnish thermostatic ...........................

4 Compression medium for airless projection 5 Packing element support .....................

6 Lacquering gun ............................................ 7

Claims (31)

 1. A method of lacquering the surface (13, 14, 15) of a packaging element (1), non-planar, small in size, and having an axis of symmetry (10), typically a capsule or a cap, metal, metalloplastic or polymer, formed of a head (11) and a skirt (12), comprising the projection under pressure, with at least one nozzle (2), typically mounted on a gun lacquering (7), a lacquer flux (3) on the surface of said packaging member (1) to form a lacquer layer (130, 140, 150), said nozzle (2) and said d packaging (1) being in relative movement or rotation of at least one turn or 3600 along said axis of symmetry (10), or translation along the length of said element or said surface to be lacquered, so as to cover the entire of the surface of said element to be lacquered, then the possible drying of said lacquer layer, and characterized in that: a) a single projecting nozzle (2) is used; t a lacquer flow on said surface, said surface being an inner or outer surface, b) said nozzle (2) has a slot-shaped orifice (20,21), of length FL greater than its width or maximum thickness FEM said projected lacquer flow forming a lamellar flow or a curtain (3), so that said lacquer flow is projected onto said inner or outer surface to be lacquered along a so-called scanning line, c) the slot of said nozzle (2) and said packaging element (1) are orientated and positioned with respect to each other so that said scanning line extends over the whole of a generatrix G of said surface to be lacquered (13, 14, 15), the entire surface being lacquered by scanning it by relative movement of said nozzle (2) or said curtain (3) and said packaging element. 2. Method according to claim 1, in which: said slit is an axial slit (20), said lamellar flux (3) has an angular opening ss less than 120, said lamellar flux (3) has a mean plane comprising said axis of symmetry (10), and projects on the distance Lo separating the extreme points (16,17) of said <Desc / Clms Page number 16>  generative, so that essentially only the surface (13, 14) of said packaging element (1) is covered by a thin layer (130, 140) of said lacquer, - said relative displacement of said nozzle (2) and said packing element (1) is a rotation R of at least one turn, in order to lacquer the entire inner (14) or outer (13) surface of said packaging element (1). 3. Method according to claim 2 wherein, said lamellar flow (3) projecting on said inner surface (14) or outer (13) with a variable angle a depending on the point of impact of said flow on said element, the width or thickness FE of said axial slot (20) varies with said angle a according to a function f (a), just as, consequently, the width or thickness RE of any flow element EF, (300) of the lamellar flux (3) corresponding passing through a fraction of slot of thickness Fa ,, said function f (a) being substantially proportional to 1 / sin a, so as to ensure a layer of lacquer (130, 140) of constant thickness whatever the angle at. 4. The method of claim 3 wherein, when said function f (a) has a cusp, in particular because said package comprises two parts, typically the head (11) and the skirt (12), connecting in a line junction (120), at an angle y, said nozzle (2) and said packaging member (1) are positioned relative to each other so that the EFM flow element (301) lacquer encountering said junction line (120) is oriented along the bisector of the angle y, and thus, the function f (a) being a continuous function, the variable width FE = f (a) of the slot is too, and therefore does not present discontinuity. 5. Method according to any one of claims 2 to 4 wherein said flow

 lamellar (3) has, in its mean plane, an angular aperture angle P at least equal to the angle PT corresponding to the angle at which the distance Lo is seen from said slot (20). <Desc / Clms Page number 17>  6. The method of claim 5 wherein the difference between the angles ssT and ss is between 1 and 5, so as to ensure the deposition of said lacquer on all of said surface (13,14) of said packaging element ( 1), while limiting the loss of lacquer. 7. Method according to any one of claims 2 to 6 wherein the form factor FL / FEM of the axial slot (20), and therefore that of the section of the laminar flow (3), is at least equal to the form factor said surface (13,14) of said packaging element, taken equal to Lo / Eo, Lo and Eo being the distances, respectively axial and radial along said axis, between end points of said surface (13,14). The method of claim 7 wherein said FL / FE form factor is at least 3. 9. Method according to any one of claims 1 to 8 wherein said nozzle (2) is fixed station and wherein said packaging element (1) is carried by a support (6) rotating along the axis of symmetry (10). ). 10. The method of claim 1 wherein it lacquered all or part of the inner surface (14) or outer (13) of said skirt (12) of said packaging element (1). 11. The method of claim 10 wherein said lacquer is projected on a fraction of the interior of said skirt which corresponds to an opening zone of said capsule, fraction of cylindrical or frustoconical shape of height h, typically between 5 mm and 50 mm, so that, in this opening area, said capsule has a layer of lacquer over a height h, said opening area may comprise an easy opening means. 12. The method of claim 11 wherein: - said slot is an axial slot (20), and projects said lacquer on the inner surface (14) of said capsule to a height h, <Desc / Clms Page number 18>  said lamellar flow (3) has an angular aperture P less than 120, said relative displacement of said nozzle (2) and said packaging element (1) is a rotation R of at least one turn, in order to lacquer the all of the inner surface (14) over a height h.  13. The method of claim 11 wherein: said slot is an annular slot (21), centered with respect to said axis of symmetry or rotation, and forming an annular ring of annular profile typically <5, - said lamellar flow ( 3) has an angular opening ss 360, - said relative displacement of said nozzle (2) and said packaging element (1) is a translation T on the distance h parallel to said axis of symmetry (10), in order to lacquer the all of the inner surface (14) over a height h. 14. The method of claim 13 wherein said slot forms an annular beam of annular profile δ greater than 50 so that said scan line extends over said height h, and thus to be able to do without said translation movement T . 15. Method according to any one of claims 1 to 14 wherein said projection under pressure is of the airless type, the lacquer itself being in this case projected under pressure, without compressed air. 16. A method according to any one of claims 1 to 15 wherein said rotational movement comprises at most 5 turns, and typically 2 to 4 revolutions. 17. Method according to any one of claims 1 to 16 wherein said pressure is kept constant and between 20 and 100 bar, or between 2 and 10 MPa. 18. The method according to any one of claims 1 to 12 and 15 to 17 wherein the length FL of said axial slot (20) is typically between 200 um and 500 <Desc / Clms Page number 19>  um, and the ratio Lo / FL is at least equal to 50, so that said lamellar flow forms an angular sector of angle P between 20 and 60.  19. Method according to any one of claims 1 to 18 wherein said spray nozzle (2) is supplied with thermostatically controlled lacquer and / or air-conditioned, so that said lacquer has a constant viscosity. 20. The method of claim 19 wherein said lacquer (4) is maintained, depending on its nature and the desired viscosity, at a temperature between 30 and 65OC and preferably between 35 and 45OC. 21. A method according to any one of claims 1 to 20 wherein said packaging element is a cap, a plugging cap or overcapping metal, aluminum or tin, metalloplastic, or polymer. 22. Method according to any one of claims 1 to 21 wherein said lacquer is a basecoat or hooking, a wax, or a coating for masking the outer surface of said element, and optionally to form the layer on which a decoration will be printed. 23. A method according to any one of claims 1 to 22 wherein said lacquer is an overprint varnish applied to the outer surface of said element previously comprising a decoration or printing, so as to protect said decor or said impression. 24. Method according to any one of claims 1 to 23 wherein said lacquer is a varnish applied to the inner surface of said element. 25. The method of claim 24 wherein said inner varnish is a solution or an emulsion, aqueous or in a solvent medium, a thermoplastic or thermosetting material. <Desc / Clms Page number 20>

 26. A method according to any one of claims 19 to 25 wherein said lacquer 31 has a viscosity, measured at 35 C and a shear rate of 103 sl, between 0.001 Pa. S and 0.01 Pa. S, and has a solids content between 20% and 45%. 27. Method according to any one of claims 2 to 26 wherein the distance Lo between the end points of the generatrix of said element is between 20 mm and 120 mm. 28. Packing element, coated with a lacquer applied by the method according to any one of claims 1 to 27 wherein the thickness of said lacquer, typically measured along a generator of said element, is in the range EM 0.3 . EM, EM being the average thickness between 5u. m and 35 μm. 29. A packaging element according to claim 28 corresponding to a capping or cap capping or over-capping, typically aluminum, coated with lacquer on the entire of its outer surface. 30. A packaging element according to claim 29 corresponding to an overcap, typically aluminum, coated with lacquer or varnish on an annular portion of its inner surface forming the opening zone of said capsule, typically of height h between 5 and 30mm.  31. Use of a method of spraying lacquer or varnish of the airless type to apply it to all or part of the outer surface and / or interior of a cap or a closure cap or overcap, lacquer itself, or the varnish, being in this case projected under pressure, without compressed air.