Patent Application
20150071696
The invention relates to a simplified sealing cap, as well as a cosmetic applicator equipped therewith.
Sealing caps of this kind for cosmetic applicators, which are composed of a tubular cap body whose interior is divided into two regions by a plate to which is attached a wand or shaft that in turn holds the actual applicator, are widely used in the cosmetics industry.
As a rule, the plate also performs the task of providing a sealing surface, which, when the sealing cap is completely closed, is pressed against the bottle neck or against the rim of the stripper protruding from this neck, in order to reliably seal the cosmetic receptacle.
In order to be able to exert the sealing pressure required for this as conveniently as possible, the cap body is provided, usually on its inner circumferential surface, with a thread profile that protrudes relatively far in the radial direction into the open space encompassed by the cap body. The thread profile constitutes a holding projection: with the aid of this thread profile, the sealing cap can be screwed onto a receptacle provided with a complementary thread groove until the plate rests with the pressure required for a reliable seal against the end surface of the receptacle neck or the stripper that encompasses this end surface.
It has, however, long been known that the thread stands in the way of a truly efficient manufacture of the sealing cap. The problem is that as a rule, these sealing caps are manufactured by means of injection molding. To this end, an injection mold is used, which is composed of two parts, between which is formed the mold cavity that produces the sealing cap. To remove the completed injection molded sealing cap from the mold, the two mold halves are pulled apart from each other in the direction parallel to the longitudinal axis of the sealing cap. However, the sealing cap is not yet completely free, even when the two mold halves are pulled all the way apart from each other. Instead, it remains attached at first to the mold half that provides the core that has produced the internal thread on the inner circumference of the cap body. In order to remove the sealing cap, it must then be unscrewed from this core in a subsequent work step. Since this problem has already existed for a long time, corresponding robots have already long ago been developed, which perform this unscrewing in a fully automated fashion. Nevertheless, the necessity for such an unscrewing increases the cycle time and necessarily incurs an additional equipment expense.
A similar problem arises in the manufacture of a sealing cap that does not in fact have a thread profile, but instead has a bayonet closure. Such a closure likewise functions with a holding projection that protrudes relatively far in the radial direction into the open space encompassed by the cap body.
In the low-budget sector, therefore, sealing caps are consistently used, which instead of an internal thread, use an elastic detent bead, which does indeed also protrude inward, but only so slightly that the sealing cap, with the aid of the linear movement of a correspondingly strong ejector, can be slid downward by the core that forms the detent mechanism, because it can expand elastically enough for the detent bead to be pulled out of the recess in the mold in which it has been formed. Such detent closures often do not remain really leak-proof over the long term since with the aid of such a detent closure, it is difficult over the long term to exert relatively powerful forces that act in the direction of the longitudinal axis L and prestress the sealing surfaces against each other with sufficient force.
In light of this, the object of the invention is to create a sealing cap that can be efficiently manufactured, even though it is provided with a holding projection that protrudes farther in the radial direction into the open space encompassed by the cap body than a mere detent bead.
According to the invention, an injection-molded plastic sealing cap is provided with a tubular cap body that has a longitudinal axis, which in many instances (but not always) will simultaneously be the symmetry axis of the sealing cap.
The cap body transitions integrally into a plate that extends at least predominantly in a radial direction.
In this case, the inner circumference of the tubular cap body is provided with at least one holding projection, which, in relation to the longitudinal axis of the tubular cap body, protrudes more than just slightly in an essentially radial direction into the open space that is circumferentially encompassed by the cap body—as a rule, the holding projection is part of a form-fitting holding mechanism by means of which it is possible to exert a holding force that is more than just insignificant in the direction of the longitudinal axis of the cap or of the receptacle associated with it. This holding mechanism is most often a thread or a bayonet closure, but in other embodiments, can be another holding mechanism that locks tight in a form-fitting manner so that the sealing cap cannot be unlocked again by purely tensile forces in the direction of the longitudinal axis.
According to the invention, the plate has a window that is associated with the at least one holding projection and is aligned with the holding projection with which it is associated, viewed in the direction of the longitudinal axis of the sealing cap. Via this window, the space situated between the holding projection and the plate, viewed in the direction of the longitudinal axis, is accessible from the side of the plate oriented away from the holding projection. This has quite a considerable advantage during the injection molding of the sealing cap because the injection mold used for this can be designed so as to significantly facilitate the removal of the completed injection-molded cap from the mold.
The injection mold can then be designed specifically so that for the removal procedure, the at least two parts of the mold can be moved away from each other in the direction of the longitudinal axis L and this action also releases the sealing cap. This is possible because the region in the sealing cap—which region is situated between the holding projection and the plate, viewed in the direction along the longitudinal axis, and which region actually represents a so-called undercut in the eyes of a mold designer—does not have to be produced by the mold part oriented toward the holding projection, but can instead be produced by the mold part oriented away from the holding projection, which latter mold part has a protruding extension for this purpose that protrudes through the window into the undercut between the holding projection and the plate.
In a somewhat more general way, it can be said that the invention is comprised of the fact that the sealing cap is provided with a tubular cap body with a longitudinal axis, which cap body transitions integrally into a plate that extends at least predominantly in a radial direction, and the inner circumference of the tubular cap body has at least one holding projection that protrudes radially inward into the inner space (8) that is circumferentially encompassed by the cap body and as a result, forms an undercut when viewed from the end opening of the tubular cap body oriented toward the holding projection, characterized in that the plate has a window that is associated with the at least one holding projection and through which it is possible to access the undercut from the end opening of the tubular cap body oriented away from the holding projection so that during production, from the end opening oriented away from the holding projection, a mold part can be slid into the region of the undercut in order to fill it, specifically so that no undercut is produced for the other mold part.
Preferably, the window is designed so that the cross-sectional area of the window is greater than the projected area of the holding projection with which it is associated, viewed in the direction of the longitudinal axis. This makes it possible for the extension that protrudes through the window to become thicker from its free end to its base because it is beveled, for example on the sides, in a conical or pyramid-shaped fashion, which improves its sealing action, for example.
Preferably, the plate is positioned in the tubular cap body so that it divides the latter into two sections, each of which has the shape of a tube that is open at the end. Particularly in cosmetic applicators, this improves handling significantly because the part of the tubular cap body protruding beyond the plate and oriented away from the applicator constitutes a counterweight to the applicator, which is fastened to the plate via a shaft or wand, so that the center of gravity of the whole system is shifted more in the direction of the middle of the cap (“middle” in relation to the longitudinal axis).
Preferably, the plate transitions into a shaft, which supports an applicator or has a coupling for the attachment of a shaft that supports an applicator.
The invention also relates to a particularly efficient-to-produce applicator with a handle, a wand, and a set of bristles as well as a method for manufacturing such an applicator. In the prior art up to now, the systematic approach has been for cosmetic applicators to be manufactured by separately producing a handle, a wand, and a bristle support with bristles extending radially out from it; these were then assembled in a subsequent step.
This approach is laborious. At the same time, this approach is also not without hygiene-related problems because particularly in the region in which the coupling section of bristle support is affixed in the wand, a narrow gap remains, which cannot in practice be completely sealed. Left-over cosmetic can collect in this gap and under unfavorable conditions, can encourage fungal or bacterial infection.
Another object of the invention is to ameliorate this situation.
This object is attained by means of a cosmetic applicator of the kind described herein.
Such a cosmetic applicator, which is in particular embodied in the form of a mascara applicator, is provided with a sealing cap whose outside is embodied in the form of a gripping surface. The sealing cap serves to tightly close a cosmetic receptacle and is embodied according to the invention in that its plate has at least one window that is aligned with the at least one holding projection, viewed in the direction of the longitudinal axis. The sealing cap transitions integrally into a shaft protruding from it. The shaft comprises a wand section and, integrally joined to it, a bristle-supporting section, i.e. the wand section and the bristle-supporting section transition seamlessly into each other and are embodied as a one-piece component. In addition, bristles protrude from the bristle-supporting section, which are embodied as an integral component of the bristle-supporting section in that they are connected to the bristle-supporting section in an undetachable, form-fitting way by means of welding. This connection is achieved through the particular embodiment of the bristle-supporting section. As such, the bristle-supporting section is specifically embodied as hollow on the inside and supports injection-molded bristles, which are integrally connected through the wall of the bristle-supporting section to a plastic core that lines the interior of the bristle-supporting section. The sealing cap and the shaft (made up of the wand section and bristle support) in this case are preferably composed of a different plastic material than the plastic core and the bristles. Ideally, these two plastic materials are selected so that they weld to each other during the injection molding of the bristles.
According to the invention, the bristles, the wand, and the cap consequently form a one-piece component. Embodying the cap according to the invention makes a significant contribution to the efficient manufacture of the applicator according to the invention since it makes the applicator, which has been produced as a single piece, significantly easier to remove from the mold. The previously required work step of inserting a coupling piece of a bristle support provided with bristles into a hollow wand and the subsequent permanent bonding of these two individual parts to each other is no longer necessary. This significantly reduces the price of the applicator according to the invention because it can be produced by means of two successive injection-molding procedures, which can be performed one after the other in a fully automatic way.
Even from a hygiene standpoint, the applicator according to the invention is advantageous because there are no assembly-related seams anywhere on it into which the cosmetic compound could penetrate, remain permanently, and then over the course of time, potentially constitute an incubator for infection.
Preferably, wherever two different plastics have been mentioned above, the first plastic compound that constitutes the bristles is composed of a plastic that in the chilled state, is more flexible and/or has a better “bend recovery capacity” than the plastic of which the second plastic compound is composed, which preferably constitutes the cap and/or the shaft. A plastic that is particularly well-suited for producing the first plastic compound is the plastic type that is marketed under the brand name “Grilflex”®. Polypropylene (PP) is particularly well-suited for the second plastic compound.
There are no serious gaps in the region of the bristle set either.
In this case, this is also true where the bristles are integrally connected to a plastic core that lines the interior of the bristle-supporting section and extend locally through the wall of the bristle-supporting section. Overall, there is an especially intimate connection between the second plastic material, which forms the bristles and is the same plastic material that fills the inside of the bristle-supporting section, and the tubular bristle-supporting section. There are no gaps anywhere that can be colonized by bacteria or fungi. Preferably, the cosmetic applicator is embodied so that the cavity of the bristle-supporting section is open toward the outside at the end surface of the bristle-supporting section oriented away from the cap. This enables a particularly favorable, bubble-free injection of the plastic compound, which is intended to locally penetrate the wall of the bristle-supporting section and form the bristles.
Ideally, the bristle-supporting section is embodied so that it has at least essentially constant wall thickness, which is ideally ≦1 mm and even better, ≦0.75 mm.
According to a preferred embodiment, the wand section is at least partially hollow and on its interior, has a dividing section that divides its cavity from the cavity of the bristle-supporting section in a pressure-tight way so that even under the influence of an injection molding pressure of several hundred bar, no perforation occurs.
Ideally, the end of the wand section oriented away from the handle is solid and thus constitutes a dividing section that represents approximately ⅕ to ½ of the total length of the wand section and provides for a reliable seal. In this way, the wand section provides a reliable seal even if the cycle times are kept relatively short and the wand section that is injection molded together with the cap in a first step has not yet completely cooled by the time the bristles are injection molded into it in a second step.
In a design that is particularly reliable and stable, the wall thickness of the bristle-supporting section increases just before the transition of the bristle-supporting section into the wand section. In this case, the wall thickness of the bristle-supporting section preferably increases toward the inside.
In a particularly advantageous embodiment, the shaft is alternatively hollow all the way through and during manufacture, constitutes a conduit through which the plastic compound, which is injected into the inside of the bristle supporting section in order to produce the bristles, can flow into the region of the cap, preferably into the region of the outer circumference of the cap. This makes it possible in a particularly efficient manner, namely in one work step with the injection molding of the bristles, to achieve a particular embodiment of the cap, preferably in the region of its gripping surface. Typically, this is done to provide the gripping surface of the cap with one or more surface regions that are composed of the softer material of the bristles (compared to the plastic material shared by the cap and the wand section) and to thus improve the haptics of the gripping surface—for example making the gripping surface more non-slip so that it is not as easy for it to accidentally slip out of the hand, for example because the applicator is being guided with fingers that are still wet/damp after showering.
It has turned out to be particularly advantageous if the outer diameter AS of the wand section is essentially or continuously greater than the outer diameter AB of the bristle-supporting section. In this case, the ratio AB/AS is preferably ≦0.8 and ideally ≦0.7. This reliably prevents the bristle set from being overstressed as it passes through the stripper and thus being damaged sooner or later.
An alternative embodiment for attaining the above-stated object is described below:
A cosmetic applicator, particularly in the form of a mascara applicator, has a sealing cap that is provided with a gripping surface and is for tightly closing the cosmetic receptacle. The sealing cap is embodied in the way explained at the beginning. The sealing cap transitions into a shaft protruding from it that ends in a bristle support, which has bristles protruding out from it. By contrast with the embodiment mentioned first, in this embodiment, the bristle-supporting section is embodied in the form of a stabilizing core. It is then encased with a second plastic compound in a second injection molding step so that a sleeve is produced, which encloses the bristle-supporting section, is welded to the entire surface thereof, and at the same time, forms the bristles protruding from its outer surface. According to the invention, the cap and the shaft, which includes the wand section and the bristle-supporting section, are composed of a first plastic material in a one-piece, one-material embodiment, while the sleeve and the bristles protruding out from it as an integral component thereof are composed of a second plastic material, also in a one-piece, one-material embodiment. The whole applicator is thus composed of only a single piece.
Preferably, wherever two different plastics have been mentioned above, the first plastic compound that constitutes the bristles is composed of a plastic that in the chilled state, is more flexible and/or has a better “bend recovery capacity” than the plastic of which the second plastic compound is composed, which preferably constitutes the cap and/or the shaft. A plastic that is particularly well-suited for producing the first plastic compound is the plastic type that is marketed under the brand name “Grilflex”®. Polypropylene (PP) is particularly well-suited for the second plastic compound.
This applicator is also very efficient to produce because it is composed of a single piece, including the bristles.
Such an applicator also has significantly improved properties from a hygiene standpoint. There is no gap between the wand and the coupling piece of a support that is equipped with the bristles. In addition, there are no serious gaps in the region of the bristle set because the sleeve equipped with the bristles and its stabilizing core are in fact welded to each other over their entire surface.
In a preferred exemplary embodiment, in this second equipping alternative just like in the first, the end of the wand section oriented away from the handle is solid and thus constitutes a dividing section that represents approximately ⅕ to ½ of the total length of the wand section. The mold, which is placed around the stabilizing core in a second injection molding step in order to encase this core with the second plastic compound that forms the sleeve from which the bristles protrude, can be pressed against this solid wand section with the pressure required to produce a reliable seal.
Another alternative embodiment for attaining the above-stated object is described below:
The cosmetic applicator, which is in particular embodied in the form of a mascara applicator, includes a sealing cap that forms a gripping surface and that is embodied in the way described at the beginning. The sealing cap transitions integrally into a shaft protruding outward from it, which in turn integrally comprises a wand section and a bristle-supporting section. In this case, the bristle-supporting section transitions integrally into bristles protruding outward from it and the whole cosmetic applicator has been injection molded in a single work step.
In the context of this alternative embodiment, the expression “injection molding in a single step” is understood to include any type of manufacture that can take place inside one and the same injection mold, without first injection molding a blank that is then entirely or partially removed from the mold in order to continue the injection molding process in another mold device.
At first, the requirement for the cosmetic applicator to be injection molded in one work step might look like a method feature that is actually irrelevant for a device claim. In this case, however, this supposed method feature constitutes an indirect property specification that stipulates a particular property for the bristles: specifically in the region of the bristles, it is of fundamental importance that in the course of being shot into the bristle-forming cavities, the plastic chains disentangle and are aligned in a direction parallel to the longitudinal axis of the respective bristle. Only then do the bristles exhibit a good bend recovery capacity similar to that of the well-known bristles, which are cut from filaments that are extruded and possibly then stretched and conventionally held between twisted wires in order to thus obtain a set of bristles. The injection molding causes an alignment of the polymer chains to occur specifically in the region of the bristles, which is why injection molded bristles clearly differ physically and in terms of their use properties from bristles that have been produced, for example, using the “rapid prototyping” method.
If one approaches the idea of injection molding a whole applicator in one step or with one shot, then the initial expectation is for there to be significant problems since it is necessary to produce relatively coarse structures (cap, plate, wand) and extremely fine structures at the same time. It has surprisingly turned out that with the inherently delicate injection molding of the cap, wand, and bristles, unexpectedly good results are achieved if an injection pressure is used that is significantly higher than the injection pressure customarily used for the injection molding of fine bristles, for example at least 900 bar or better still, at least 1200 bar. With this approach, it is apparently possible to compensate for the fact that when injection molding a whole applicator in one piece, the plastic compound that is injected into the comparatively large-volume mold cavity must travel longer distances therein before it can travel into the bristle-forming mold cavities and is then already cooled too much to still be able to form bristles therein that have truly good mechanical properties.
It should be noted that it is particularly advantageous if the outer diameter of the wand section is essentially or continuously greater than the outer diameter AB of the bristle-supporting section. In this case, the ratio AB/AS is preferably ≦0.8 and ideally ≦0.7.
At the transition to the bristle-supporting section, the outer diameter of the wand section advantageously decreases relative to the outer diameter of the wand section elsewhere.
For each of the three alternative embodiments mentioned above, it is advantageous to provide the sealing cap with one or more holding projections, which is/are embodied so that in cooperation with one or more holding projections provided on the receptacle, it/they produce(s) a quick acting closure for the applicator, which closure is embodied as a bayonet closure or preferably as a multi-start short thread and is laid out so that with a rotating movement ≦⅜ of a turn and better still, with a rotating movement ≦¼ of a turn, the holding elements can be moved from a completely closed position into a position in which they are no longer attached to each other in a direction along the longitudinal axis of the applicator.
Preferably, the short thread provided as a wand thread is embodied with a pitch angle μ of preferably greater than 5°. With the aid of such a short thread, despite the fact that the thread is only turned a short distance in the closing direction until it has reached its closed position, a reliably sufficient sealing pressure can be produced between the applicator and the cosmetic receptacle with which it is associated (in the direction parallel to the longitudinal axis of the applicator).
In all three embodiments, it has turned out to be advantageous if the plate has an opening, which connects the cavity of the wand section to the adjacent cavity that is encompassed in the circumference direction by the cap. This is because a wand that is solid all the way through has turned out to be disadvantageous due to the high consumption of material and the long cooling times.
Other possible embodiments, operating methods, and advantages ensue from the following description of exemplary embodiments based on the figures.
As shown in
As shown in
The holding projections 6 on the sealing cap protrude radially inward into the inner space 8 enclosed by the cap body 3. In a way similar to the holding projections 5 on the receptacle, the holding projections 6 on the sealing cap have only a locally limited span, whose radian measure is preferably less than 1/10 and ideally less than 1/15 of a full circle. In this exemplary embodiment as well, the holding projections 6 on the sealing cap do not have a thread pitch.
In this exemplary embodiment, the holding projections 5 and 6 are matched to each other so that each of the holding projections 6 on the sealing cap engages under the holding projection 5 on the receptacle currently associated with it and preferably engages with it in a form-fitting way as soon as the closed position is fully achieved, see
In this way, the cooperation of the receptacle neck with the sealing cap shown in
The one-piece sealing cap 2 with its tubular cap body 3 is shown with a continuous black color and is thus clearly visible. The inner space 8 of the sealing cap enclosed by the tubular cap body 3 is divided by a plate 4 into two sections that are separate from each other. The plate 4 is used for fastening the wand or shaft, not shown, or even transitions integrally into it.
The injection mold to be used for the one-piece manufacture is composed of a first mold half 9 and a second mold half 10, as indicated by the different cross hatchings. To remove the injection molded part after it has cooled sufficiently, the two mold halves must be moved away from each other in the direction of the arrows P, parallel to the longitudinal axis L of the sealing cap. In this case, the problem arises that the projections 6 on the sealing cap form an undercut H, which makes it impossible to remove the sealing cap from the second mold half 10, see
For each holding projection 6, the plate has a window 11 that is aligned with the associated holding projection 6, viewed in the direction of the longitudinal axis L of the sealing cap. The free cross-sectional area of the window 11 in the direction of the longitudinal axis L is at least as large as the projected area of the holding projection with which it is associated, viewed in the direction of the longitudinal axis L. In the present case, the free cross-sectional area of the window 11 is also larger for the reasons to be explained in greater detail below.
At this point, it should be noted that each of the windows 11 actually has only a locally limited span in both the radial and circumferential directions so that wherever there is no window 11, the plate 4 is integrally joined to the cap body 3.
As is clear from
Upon closer inspection of
For the same reason, it is particularly advantageous (even if not absolutely required) to also embody the side surfaces of each tongue oriented in the circumference direction as conical or wedge-like.
It is clear that as a result, the free cross-sectional area of the windows 11 is greater than the projected area of the holding projections 6 at least in the radial direction, while ideally, it is in fact greater than the projected area of the holding projections 6 in both the radial and circumference directions.
It is also important for the window 11 not to extend too far in the radially inward direction so that despite the presence of the window or windows, an uninterrupted sealing section 15 remains that is completely closed in the circumference direction. This sealing section 15 can be pressed against a corresponding counterpart surface on the neck of the cosmetic receptacle or on the collar of the stripper that overlaps the neck, and thus tightly seals the cosmetic receptacle.
Preferably, this sealing section 15 is embodied in the form of a closed annular disk that is situated between the shaft lug of the plate 4 and the projection of the holding projections 6, in a plane or set of planes extending orthogonal to the longitudinal axis (L) of the sealing cap.
Based on the above explanations of
The drawing clearly shows the holding projections 5 and 6, which engage behind each other in a form-fitting way and thus press the remaining sealing section 15 on the plate 11 snugly against the collar 17 of the stripper 16 that extends beyond the end surface 18 of the receptacle neck.
The drawing also clearly shows the windows 11, two of which are preferably provided on diametrically opposing sides.
This drawing shows even more clearly the interplay of a holding projection 5 on the receptacle with a holding projection 6 on the sealing cap. The drawing also shows how the holding projection 6 on the sealing cap forms a detent recess into which the convex contact surface of the holding projection 5 on the receptacle snugly fits so that a form-fitting detent engagement is produced.
The drawing also clearly shows the window 11 associated with the holding projection 6 on the sealing cap.
In this case, the drawing clearly shows the uninterrupted plate 4, which has no windows in this region.
Finally,
In this case, the drawing clearly shows the one of the preferably two windows 11 and its alignment with the holding section 6 situated beneath it in the direction of the longitudinal axis (L), while the other window has been eliminated by the section. The drawing also clearly shows the sealing section 15 and the fact that the plate 4 is uninterrupted, i.e. not interrupted by a window, across other regions.
In principle,
The preferred embodiment of the holding projections 6 on the sealing cap are shown with particular clarity here. Unlike the holding projections 5 on the receptacle, the holding projections 6 on the sealing cap are preferably not embodied as wings that are completely free on all sides and are only attached on a single side. Instead, the holding projections 6 on the sealing cap preferably transition on their one side into a stop 19 for the stop projections on the receptacle, thus preventing an overtightening that would cause the already fastened sealing cap 3 from coming loose again. The stop 19 predetermines a defined closing position of the sealing cap 3 relative to the receptacle 7 so that when in the fully closed position, the sealing cap 3 and the receptacle 7 have a visually attractive appearance, even if they are not round.
Ideally, the holding projections 6 on the sealing cap essentially form the shape of an L that is bonded with its one side flank to the inner surface of the sealing cap 3, with its one leg constituting the actual holding projection that engages beneath the holding projection 5 of the receptacle and with its other leg constituting the above-mentioned stop projection 19.
The second exemplary embodiment differs from the first exemplary embodiment in that here, the holding projections on the sealing cap and on the receptacle are each provided with an inclination so that they function in a manner similar to a screw. Apart from this fact, it is functionally identical to the first exemplary embodiment so that statements made regarding the first exemplary embodiment also apply to this second exemplary embodiment, provided that nothing to the contrary is stated below.
It is important that even though they have an inclination, the holding projections each extend over only a small part of the circumference, preferably within the limits that have already been described for the first exemplary embodiment.
The design described in detail above, in which the sealing surface 15 is embodied in the form of an annular disk, which is preferably also implemented in this embodiment as well, can be made smaller or even be eliminated if the plate transitions into a sealing cone D, which the thread action of the holding projections 6 presses firmly into the correspondingly embodied inner circumference of the stripper, as illustrated in
The Applicators According to the Invention that can be Efficiently Manufactured Through Involvement of the Sealing Cap According to the Invention
The sealing cap according to the invention is ideally suited for use in the construction of one-piece applicators in which the sealing cap, whose plate, the adjoining wand or shaft, and the bristle support including its bristle set are composed of a single piece, which is injection molded in a single step or in two successive steps.
First Applicator Type
First, a description will be provided below in conjunction with
The one-piece applicator according to the invention is composed of a sealing cap 2 embodied according to the invention, which is integrally joined to a shaft 20, see
As
In this case, a plate 4 preferably serves as a connecting element between the shaft 20 or its wand section 21 and the sealing cap 2. This plate extends essentially in the radial direction relative to the longitudinal axis L and is embodied in the way already described above. The plate is preferably positioned so that it divides the tubular cap body composing the sealing cap 2 into two sections, with the length of the section oriented toward the applicator preferably representing approximately ⅓ the length of the section oriented away from the applicator. In this case, the plate 11 preferably has a plate opening 32 in the middle. The plate opening 32 permits the plate to be penetrated by a molding core, which ensures that the shaft 20, in the region of its wand section 21, can be embodied as hollow on the inside, and can possibly form a sealing cone for producing a seal relative to the stripper; the corresponding cavity is labeled with the reference numeral 32.
The wand section 21, however, does not absolutely have to be embodied as hollow over its entire length. Instead, it is preferably embodied so that its distal end, i.e. the end oriented away from the sealing cap 2, is embodied as solid. Preferably, the wand section 21 is embodied as solid at least to a length LL (see
Ideally, the outer diameter of the wand section 21 decreases in the region of its distal end, i.e. the end oriented away from the sealing cap 2; this is also visible in the figures.
The distal end of the wand section 21 is integrally joined by the bristle-supporting section 22, as is clearly shown in particular by
Bristles 23 oriented outward in an essentially radial direction protrude from the bristle-supporting section 22, as schematically depicted in
The bristles 23 are injection molded bristles, i.e. bristles that have been given their shape by the corresponding cavity of an injection mold into which they have been shot at high pressure, as a rule, which will be discussed in greater detail below. The injection molding according to the invention also gives the bristles their definitive physical use properties because in injection molded bristles that have been manufactured using the method that defines the invention, the polymer chains that constitute the bristles demonstrate a special orientation parallel to the longitudinal axis of the bristle.
The term “bristles” refers preferably to application elements of the kind shown in
The bristles 23 are injection molded so that the plastic compound that forms the bristles is injected at a correspondingly high pressure into the cavity 24 of the bristle-supporting section 22. This bristle-forming plastic compound, which is preferably a plastic compound that is different from the one of which the main component 31 has been produced, penetrates the wall of the bristle-supporting section 22 at all of the points at which, viewed in the radial direction, an empty, bristle-forming cavity is situated behind the bristle-supporting wall of the section 22. In this way, it shoots into the above-mentioned cavity. This produces bristles that extend through the wall of the bristle-supporting section 22 and are integrally connected to the solid core that fills the cavity 24 of the bristle-supporting section 22 in a completed brush and are welded to it, see
The sequence of the manufacturing method for the applicator according to the invention can best be seen in
In a first method step, the main component 31 is injection molded as a one-piece component; the injection molding of the sealing cap 2 is carried out as described in the beginning in conjunction with
As soon as this plastic compound has sufficiently cooled, preferably the second slider 28 is withdrawn first and then the first mold end piece 27 is removed, see
Preferably, the components of the injection mold, which at this point still contain the main component, are turned in order to bring the bristle-supporting section 22 to the side of the injection point in order to subsequently be able to connect the mold encompassing it to the injection point.
The region of the main component that is freed by the removal of the first mold end piece 27 is then inserted into a second mold end piece 29, as shown in
These cavities 30 are empty at first and their mouths are initially covered by the wall of the bristle-supporting section 22. In a next step, the bristle-forming plastic compound is injected from the side of the arrow E into the cavity 24 of the bristle-supporting section 22. The plastic compound exerts a powerful pressure against the wall of the bristle-supporting section 22 from the inside so that ultimately, the plastic compound breaks through the wall of the bristle-supporting section 22 wherever the wall is covering the mouth of a bristle-forming cavity 30. In this way, the plastic compound shoots into the bristle-forming cavities. Once this has happened, a pause occurs until this second plastic compound has hardened enough to retain its shape. Then the finished applicator is completely removed from the mold.
In this exemplary embodiment, the second mold end piece 29 is segmented like pieces of cake so that the individual parts of the mold end piece 29 can be moved away from one another in the radial direction in order to thus be able to remove the bristles from the mold without tearing them. Then the first slider 26, which is embodied according to
The key point is that this method produces a completely finished applicator in one cycle, without having to remove individual components from the injection molding unit and convey them to another station in order to assemble them there.
This exemplary embodiment corresponds in its entirety to the first exemplary embodiment described in detail above so that statements made regarding the first exemplary embodiment also apply to this second exemplary embodiment, provided that nothing to the contrary is indicated by the differences described below.
The second exemplary embodiment features the fact that in it, the shaft 20 is hollow inside along its entire length. Unlike the first exemplary embodiment, the second exemplary embodiment therefore has no dividing section that is embodied as solid.
Otherwise, as shown by
The elimination of the solid dividing section makes it possible to provide a conduit through which the second plastic compound K, which is injected in order to form the bristles, flows through the shaft 20 into the region of the sealing cap 2. Preferably, the second plastic compound K also flows into the region of the outer circumference of the sealing cap and for example forms a gripping surface that is especially haptically and/or visually attractive.
This makes it possible in a particularly efficient manner, namely in one work step with the injection molding of the bristles, to produce a particularly advantageous gripping surface on the sealing cap 2. In this case, care must absolutely be taken that the slider 31—which is inserted instead of the first slider 26 in order to carry out the second injection molding step in which the bristles are produced—covers the windows 11 so that the second plastic compound cannot penetrate into the region of the undercut that is opened up upon withdrawal of the first slider 26, also see
Second Applicator Type
The above-described one-piece applicator and the above-described “two-shot” injection molding method for manufacturing an applicator that is composed of one piece overall are not the only possibility for the beneficial use of the sealing cap explained at the beginning.
On the contrary, there is alternatively also the possibility of a modified two-shot injection molding method that is carried out in the sequence explained below and that produces a corresponding applicator. Since the above-described applicator and the modified applicator described below only differ in details relating to their bristle sets, statements made with regard to the above-described exemplary embodiment also apply to the additional exemplary embodiment, provided that nothing to the contrary is indicated by the differences described below.
Once again, the main component 31 shown in
In this case, care is taken that the main component 31 has a sufficient jump in diameter between its bristle-supporting section 22 and its wand section 21. As a rule of thumb, the diameter of the bristle-supporting section should be less than 0.5 times the diameter of the wand section before the injection molding of the bristles.
In the finished applicator, the bristle-supporting section 22 is preferably enclosed by a sleeve composed of plastic that is injection molded onto it and welded to its entire surface—i.e. the plastic that forms the bristles. Consequently, bristles 32 that are oriented outward in an essentially radial direction protrude from the finished applicator, as schematically depicted in
The bristles 23 are injection molded bristles, in other words bristles that have been given their shape by the corresponding cavity of an injection mold into which they have been shot at high pressure, as a rule, which will be discussed in greater detail below. The injection molding according to the invention also gives the bristles their definitive use properties because in injection molded bristles that have been manufactured using the method that defines the invention, the polymer chains that constitute the bristles demonstrate a special orientation parallel to the longitudinal axis of the bristle. As a rule, this requires the bristles to be injection molded using a correspondingly high injection pressure. Preferably, the injection pressure is ≧900 bar. In this case, each of the bristle-forming cavities is ventilated, preferably at several points, to be specific, ideally not only at the end of the bristle-forming conduit, but also between the beginning and end of each bristle-forming conduit.
The manufacturing method described above for the first applicator type is used to manufacture this second one-piece applicator type, but using a first mold end piece 27, which as a rule does not have a slider, and a modified mold end piece 29. In this regard, reference is hereby made to
Third Applicator Type
Finally, there is also a third possibility for manufacturing a novel applicator using the sealing cap according to the invention.
This applicator is continuously composed of a single plastic material, from the sealing cap to the bristles.
In this regard, reference is hereby made to
In this specific embodiment, it has turned out to be particularly advantageous to select an elevated injection pressure of ≧900 bar. In addition, the bristle cavities should also be embodied correspondingly; their greatest diameter should be smaller by at least a factor of 10, or better still a factor of 15 than their maximum length in the direction of the longitudinal axis of a bristle. Preferably, each of the bristle-forming cavities is ventilated at several different points spaced apart from one another.
The injection molding according to the invention, in particular at the above-mentioned elevated injection pressure, also gives the bristles their definitive use properties because in injection molded bristles that have been manufactured using the method that defines the invention, the polymer chains that constitute the bristles demonstrate a special orientation parallel to the longitudinal axis of the bristle.
As has already been mentioned above, method protection is also claimed at the relevant time, in fact particularly in the form of the following claims:
A method for manufacturing a cosmetic applicator 1 according to one of the claims in which, in a first method step, preferably through the use of an injection molding method, a blank is manufactured, which is constituted by a sealing cap 2 that forms a gripping surface on its outer circumference and is for tightly closing the cosmetic receptacle, which cap transitions integrally into a shaft 20 that protrudes from it and forms a wand section 21 and a bristle-supporting section 22, and in a second manufacturing step, the bristles 23 are injection molded onto the bristle-supporting section 22 either so that the bristle-forming plastic compound is injected into the hollow interior/cavity 24 of the bristle-supporting section 22, where the injection pressure is on the one hand selected to be high enough that the bristle-forming plastic compound breaks through the wall of the bristle-supporting section 22 in the radially outward direction wherever the wall is hollow because it is covering a bristle-forming cavity that is not yet filled at the beginning, and on the other hand is selected to be low enough that the bristle-forming plastic compound does not break through the still-warm, solid dividing section of the shaft 20 that prevents the bristle-forming plastic compound from being shot in the direction of the sealing cap 2 or so that the bristle-supporting section 22 is enclosed by and welded to a sleeve from which the bristles protrude.
A method according to the description provided in the above paragraph, characterized in that after the injection molding of the blank, the bristle-supporting section 22 is removed from the mold in which it is produced, while the rest of the blank remains in the mold cavity of the main mold used to manufacture it and is then inserted into a second mold that fully encloses its outer circumference, which has bristle-forming cavities and is brought into sealed contact with the shaft 20.
A method according to the claims and according to the description provided in the above paragraphs, in which—after the bristle-supporting section 22 is removed from the mold forming it—the main mold is rotated and only then is the bristle-supporting section 22 inserted into the mold that forms the bristles 23.
A method according to the description provided in the three preceding paragraphs, in which the parting line between the main mold and the mold that produces the bristle-supporting section lies in a plane that intersects the solid dividing section of the shaft 20.
The above-mentioned methods can include other method features or device features taken from the part of the description preceding them or from the claims.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202013006927.9 | Aug 2013 | DE | national |
