Abstract:
A pen includes a shank that has a reservoir and an applicator tip for an application fluid that includes a solvent that is volatile at room temperature. The pen also includes a closure cap that is fitted onto the shank. The closure cap has a cavity that accommodates the applicator tip. The closure cap includes a storage chamber for accommodating a sacrificial liquid that is volatile at room temperature. The closure cap also has a connecting channel that communicates with the storage chamber and the cavity.

Description:
BACKGROUND OF THE INVENTION 
     Field of the Invention 
     The invention relates to a pen having a closure cap. 
     Such pens comprise a reservoir for storing an application fluid and also an applicator tip for applying the fluid to a surface. The application fluid contains a solvent which is volatile at room temperature and, following application, evaporates and thus makes it possible for the application fluid to dry on or form a film. The pens comprise a closure cap which can be removed from the pen in order for the latter to be used and which has a cavity intended for accommodating the applicator tip. 
     Such pens are known today in a variety of different embodiments, e.g. in the form of writing implements such as fountain pens, touch-up pens or multimarker pens for applying ink or paint, but also, recently, in the form of implements used for cosmetics purposes, such as nail-polish or mascara applicators for applying, for example, a paste. The applicator is, for example, a brush, a sponge or a fiber or sintered tip. Examples of conceivable solvents are water, but also solvents such as ethyl acetate, butyl acetate, propyl acetate, ethanol, isopropanol, butyl alcohol or diacetone alcohol, for example for nail polishes. 
     Solvents are divided up in accordance with volatility or evaporation number, which describes the tendency of a solvent to evaporate. High-volatility solvents are those with an evaporation number of less than 10, medium-volatility solvents are those with an evaporation number of 10 to less than 35 and low-volatility solvents are those with an evaporation number of 35 or more. The present patent application deals with solvents with evaporation numbers of less than 35, in particular of less than 10. 
     The problem with the pens described is that, despite a closure cap being fitted, drying out of the applicator tip can be observed. This is due, on the one hand, to the fact that it is not possible, with reasonable outlay, for the closure cap to be fitted in a fully gas-tight manner on the pen. On the other hand, in particular in the case of closure caps produced from plastic, it is also possible for solvents to diffuse through the material of the closure cap. 
     DE 19 01 668 U discloses a drawing pen which has a water-filled storage element in the cap region for safeguarding against drying out. 
     It is known from DD 206 548 for the storage element, when the cap has been pulled off, to be closed by a valve which is actuated by the drawing tip. 
     BRIEF SUMMARY OF THE INVENTION 
     It is an object of the present invention to improve a pen of the type mentioned above. 
     The invention is based on the general concept of the closure cap of a pen of the type mentioned in the introduction containing a storage chamber and a connecting channel, which connects the storage chamber fluidically to the cavity, the storage chamber serving to accommodate a sacrificial liquid which is volatile at room temperature. The sacrificial liquid here contains at least one solvent which evaporates from the liquid phase into the gaseous phase. The gaseous phase of the sacrificial liquid will be referred to hereinbelow, for short, as a sacrificial solvent. 
     The sacrificial liquid thus evaporates to form a sacrificial solvent and passes through the connecting channel into the cavity, where, with the closure cap fitted, the sacrificial solvent encloses the applicator tip and impregnates the cavity. In other words, instead of the solvent of the application fluid, the sacrificial liquid then evaporates to form a sacrificial solvent. This configuration of the closure cap prevents the applicator tip, or the application fluid thereon, from drying out. 
     The vapor pressures of the solvent of the application liquid and the vapor pressure of the sacrificial liquid are thus added to one another in the cavity. The gas phase or vapor phase in the cavity of the closure cap is thus made up both of the sacrificial liquid and from the solvent of the application liquid. Accordingly, leakage on account of a lack of sealing between the closure cap and pen shank takes place at the expense of the solvent of the application liquid and of the sacrificial liquid. As a result, the applicator tip itself cannot dry out, or drying out is delayed. In addition, thickening of the application liquid on account of loss of solvent is prevented or delayed. 
     The sacrificial liquid may be the solvent of the application fluid, or may contain the same. When the covering cap is in the plugged-on state, the application fluid is thus enclosed by its own solvent, although the latter comes, in part, from the storage chamber. Evaporation of solvent from the application fluid or drying out of the applicator tip is thus avoided in a particularly effective manner. 
     Generally the vapor pressure of the sacrificial liquid or of the sacrificial solvent should be comparable to, or higher than, the corresponding value of the application fluid or of the components thereof, that is to say the boiling point should be lower. 
     According to the invention, the closure cap contains a sealing element, which can be moved between a sealing position, in which it closes the connecting channel, and an opening position, in which it frees the connecting channel. The sealing element here, for movement between the opening position and sealing position, is coupled for movement to a portion of the pen shank which projects into the cavity of the closure cap. In other words, when the covering cap is being fitted or pulled off, this shank portion, as a result of the movement coupling, moves the sealing element and respectively frees the connecting channel or closes the same. Thus, when the closure cap is in the fitted state, the connecting channel is open, in which case—as has been described above—the sacrificial liquid can evaporate and pass to the applicator tip. When the closure cap has been removed, the cavity is in connection with the surroundings. In this case, however, there is no sacrificial solvent passing through the closed connecting channel to the cavity and, from there, into the surroundings. Unnecessary release of evaporating sacrificial liquid into the surroundings is thus prevented. This sacrificial liquid or the sacrificial solvent remains in the storage chamber, which is now closed off from the exterior surroundings. Since actuation takes place by way of the pen shank, the pen tip remains free of mechanical loading. This is important, for example, for fine fiber tips which must not be subjected to deformation. 
     In a preferred embodiment, the sealing element is mounted in an axially displaceable manner in the cap. The axial movement is a basic movement which generally takes place when the pen cap is being fitted or pulled off. If the sealing element is likewise mounted in an axially displaceable manner in the closure cap, the plug-on or pulling-off movement or relative movement between the pen shank and closure cap can easily be converted, by straightforward movement coupling, into the axial movement of the sealing element in the closure cap. 
     In a further preferred embodiment of the invention, the sealing element comprises a wall segment which delimits the storage chamber from the cavity. The wall segment here leaves free merely at least one longitudinal portion of the connecting channel in order for it to be possible for this to extend through the wall segment or to extend past the same. The sealing element also comprises a driver element, which interacts with the shank portion and is directed toward the cap opening in order to come into engagement there with the shank portion. In other words, that is to say that, during the operation of plugging on or pulling off the closure cap, the driver element is moved by the shank portion, which, in turn, actuates the closure mechanism of the sealing element, e.g. in the form of a movement of the wall segment. The wall segment, as part of the sealing element, may likewise be mounted in an axially displaceable manner in the closure cap. 
     In a further preferred embodiment, a gap is present between the inside of the closure cap and the wall segment, and this gap forms at least one longitudinal portion of the connecting channel. The gap here may be, in particular, an annular gap encircling the wall segment. The annular gap may then be of such a small width that, for example, liquid sacrificial medium is retained in the storage chamber by the annular gap and only vaporous medium, that is to say evaporated sacrificial liquid or sacrificial solvent, can pass through the annular gap to the cavity. The annular gap then forms a diffusion section. 
     In particular here it is possible for the flow cross section of the gap to be smaller than that of the rest of the connecting channel. The gap then essentially determines the flow behavior of the connecting channel. It is thus possible to ensure, for example by dimensioning of the gap, that the correct quantity of sacrificial solvent passes into the cavity precisely quickly enough in order to protect the applicator tip from drying out. 
     In a preferred embodiment, the gap may be an annular gap. This is easy to achieve in particular for rotationally symmetrical pens. 
     In a further preferred embodiment, in the event of a corresponding gap being present, a closure element is arranged on the inside of the closure cap and closes the gap in the closing position of the sealing element. In other words, when it moves, the sealing element moves with sealing action against the closure element. 
     In a particularly preferred embodiment, this closure element may be an encircling annular protrusion. Such an annular protrusion interacts for example particularly straightforwardly with an annular gap encircling the wall segment in that the wall segment slides in the manner of a piston, leaving free the annular gap in the cylindrical covering cap in the process, until it meets the annular protrusion, which then closes the annular gap. 
     A particularly compact configuration of the pen is achieved if the sealing element is at least part of an inner cap arranged within the closure cap. A corresponding inner cap may be produced particularly straightforwardly and cost-effectively for example by injection molding, is stable and forms the cavity on its inside and can be straightforwardly mounted in particular in an axially displaceable manner in the closure cap. The connecting channel, or at least part thereof, may then be formed particularly straightforwardly as a through-passage in the inner cap. 
     According to a development of the abovementioned embodiment with wall segment and driver element, the inner cap may then comprise these two components. It is possible here for the inner-cap base, which is directed away from the cap opening, to constitute the wall segment. In this region, the annular gap may then be formed between the inner cap and closure cap. The inner-cap wall which extends away from the base can then form the driver element, or contain the same. 
     In a further preferred embodiment of the invention, the pen comprises a first axially effective form fit, which restricts the relative movement between the sealing element and closure cap when the latter is removed from the shank. A second form fit, which brings about the movement coupling between the sealing element and shank portion when the closure cap is pulled off, is formed between these two elements. The first form fit here, as seen in the axial direction, has a higher level of strength than the second. 
     A corresponding configuration of the pen makes it possible to realize the following movement sequence when the pen cap is being removed: a user grips the closure cap and begins to unscrew, or pull off, the same from the pen. The sealing element here is still held firmly on the shank via the second form fit, as a result of which the pulling-off movement of the closure cap results, in the first instance, in a relative movement between the closure cap and sealing element. It is only when the closure cap has been pulled off the pen and/or sealing element to the extent that the first form fit engages that any further relative movement between the closure cap and sealing element is prevented. When the closure cap is subjected to further force during the pulling-off movement, however, in the first instance the second form fit is disengaged, i.e. the sealing element releases its movement coupling to the shank. In other words, the entire closure cap is released from the shank. 
     The corresponding relative movement between the closure cap and sealing element in this case results first of all in the connecting channel being closed, in which case the latter is already closed when the sealing element is detached from the shank. When the closure cap is plugged onto the pen, in the first instance the sealing element is pushed back again into the closure cap and, finally, the sealing element latches on the shank. 
     In a preferred embodiment, the two form fits are respectively formed in each case by radially overlapping protrusions on the closure element and sealing element, on the one hand, and on the sealing element and shank portion, on the other hand. 
     It is conceivable to use, for example for the first form fit, a stop element, which bounds the relative movement between the sealing element and closure cap when the closure cap is being removed from the pen, and, for the second form fit, a latching element, which retains the sealing element in the first instance on the shank when the closure cap is being removed. The latching force of the latching element here is smaller than the stopping force of the stop element, for which reason, when the closure cap is being pulled off, only the second form fit releases when the first is subjected to stopping action. 
     The first form fit may be formed, in particular, by a stop arranged on the closure cap and by a protrusion arranged on the sealing element. The second form fit may be formed by a latching nose on the shank portion and a latching protrusion on the sealing element. Such a solution is easy to realize, for example, by injection molding. 
     In a further preferred embodiment, the closure cap has a covering which is coupled for movement to the sealing element and, when the closure cap is in the released state, conceals a portion of the closure cap which adjoins the opening. The closure cap, in this portion, usually has a retaining element, e.g. a screw thread, a bayonet closure or a frictional or snap-fit connection, which arrests the closure cap on the shank. The covering then conceals this retaining element when the closure cap is in the released state. In other words, when the closure cap is being pulled off the pen, as explained above, the sealing element moves, and this sealing element in turn, via movement coupling, guides the covering into a position in which it conceals the retaining element. When the closure cap is later fitted onto the pen, the retaining element is thus concealed in a first instance, for which reason the retaining element, that is to say for example the thread, cannot be soiled by application fluid. As a result of the plug-on movement and the corresponding movement coupling to the sealing element, the covering is moved away from the retaining element as the closure cap is being plugged on, in which case the retaining element, finally, can grip on the pen in order to arrest the closure cap thereon. 
     In a further preferred embodiment of the invention, the storage chamber contains a storage element for the sacrificial liquid. This storage element may be, for example, a fiber element or sintered element. Within the storage chamber, the sacrificial liquid is then stored in the storage element. 
     However, it is also conceivable for the storage chamber to be closed by a semipermeable membrane, in order thus to create a retaining volume for the sacrificial liquid. The membrane could also fill, for example, the abovementioned diffusion gap or channel, or form the same. The membrane may then also serve for metering the quantity of solvent dispensed per unit of time, or be configured accordingly. 
     In a preferred embodiment, the storage element may be a cartridge, that is to say a receptacle filled with sacrificial liquid. Rather than the entire closure cap, it is therefore only the cartridge which need be suitable for storing the sacrificial liquid, e.g. configured in an appropriately material-compatible manner. This also gives rise to the advantage that the cartridge can be filled prior to completion of the pen as a whole and, in the filled state, can be inserted into the closure cap or the storage chamber during assembly. The cartridge here is, for example, a liquid cartridge with wick. 
     The organic solvents which are possible as the sacrificial liquid here have a high vapor pressure, often pose a health hazard and, in particular, are highly flammable. Appropriate precautions, in particular fire protection measures or explosion protection measures, have to be put in place for handling such substances. The advantage with using a cartridge is that the cartridge can be filled in a separate method step. It is only during production of the cartridge, and only in that area, that the precautions then also have to be taken, this being easier to manage than providing precautionary measures throughout the production of the pen. For the actual assembly of the pen, there is then no longer any need for precautions because the cartridge can be supplied in the closed state to the assembly line. The operation of assembling the pen can then be carried out easily and straightforwardly. The cartridge has to be closed such that the sacrificial solvent can pass in a controlled manner into the closure cap. Conceivable here for example is a membrane or a sintered disk. 
     The cartridge should thus be closed when it is supplied to the assembly line. Either the wall thickness of the cartridge, at least at one location, is selected to be thin enough to allow it to be pierced, with a small opening then being formed, when it is fitted in the pen. Sacrificial liquid then can escape through this opening not in the free-flowing state, but probably in the form of liquid vapor. As an alternative, it is conceivable for the cartridge wall to contain an opening which is closed, for example by a plastic film or the like, following filling. The closure element can likewise be pierced, or pulled off, at a later stage. A further option is for the opening of the cartridge to be closed by a material which is permeable for the liquid vapor. Such an opening, of course, likewise has to be closed, for example using an adhesively attached film or in some other way. 
     A further advantage of a cartridge is that a relatively large quantity of sacrificial liquid can be accommodated in the closure cap. This is because the cartridge—for example in contrast to a storage element being used—need not contain any storage material with capillary action, since the sacrificial liquid is already retained by the cartridge. 
     The cartridge can be introduced into the closure cap, or the storage chamber thereof, through the customary single opening of the closure cap, which also serves to fit the latter onto the pen. It is also conceivable however, in an alternative embodiment, for the closure cap, in the region of the storage chamber, to have a through-passage in which the cartridge is accommodated with sealing action. In other words, the cartridge thus forms part of the closure cap or continues the latter in the region of the through-passage. During assembly of the pen, the cartridge can then easily be inserted into the closure cap from the inside or outside. It is also, for example, possible to provide a viewing window in the cartridge itself, this viewing window then being visible as part of the closure cap and allowing the quantity of sacrificial liquid which is still present to be checked. 
     In an alternative embodiment, at least part of the cartridge is integral with the abovementioned inner cap. This is easily possible, for example, by injection molding; there is then no need for a separate component to be produced for the cartridge. 
     In an alternative embodiment, at least part of the connecting channel is designed in the form of a capillary channel. It is then not absolutely necessary for the channel to be closed by a sealing element. A seal between the inner and outer caps may then be, for example, fixed, that is to say non-displaceable. The inner cap also has to be mounted, for example, in a non-displaceable manner in the closure cap. Capillary channels which open out into the storage chamber are then located between the inner and closure caps and between a seal, accommodated therebetween, and the cap. The capillary channels, at the same time, open out into the cavity, in which case sacrificial solvent can evaporate out of the storage chamber, through the channels, into the cavity. 
     The capillary channels here can also narrow in the direction of the storage chamber. It is not then possible, on account of the directed capillary force, for sacrificial liquid to run out of the storage chamber. 
     The capillary channels may be formed by grooves or flattenings on the outside of the seal or the inside of the closure cap or the outside of the inner cap. 
     For further description of the invention, reference is made to the exemplary embodiments in the drawings, in which, schematically in each case: 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         FIG. 1  shows a pen with fitted closure cap, 
         FIG. 2  shows the detail II from  FIG. 1 , 
         FIG. 3  shows the detail III from  FIG. 1 , 
         FIG. 4  shows the pen from  FIG. 1  as the closure cap is being pulled off, 
         FIG. 5  shows the detail V from  FIG. 4 , 
         FIG. 6  shows the closure cap from  FIG. 1  pulled all the way off the pen, 
         FIG. 7  shows the detail VII from  FIG. 6 , 
         FIGS. 8-10  show sections through VIII, IX and X in  FIG. 4 , 
         FIG. 11  shows a pen with a cartridge as storage element, 
         FIG. 12  shows a cartridge integrally formed on the inner cap, 
         FIG. 13  shows a closure cap with a through-passage and a cartridge inserted from the outside, and 
         FIG. 14  shows a cartridge inserted from the inside. 
     
    
    
     DESCRIPTION OF THE INVENTION 
       FIG. 1  shows a pen  2  having a shank  4 , of which only the front part is shown. A cap  6  has been fitted onto the shank  4  by way of its opening  24  since the pen is not currently being used, that is to say is located in a closure or storage position. The shank  4  here closes the opening  24 . The shank  4  essentially comprises a container  8  which forms the basic body, or grip body, of the pen  2  and has a reservoir  10  for an application fluid  12  with a solvent  13 . The shank also comprises a shank portion  14  which is fitted onto the container  8  on the end side, acts as an adapter and carries an applicator tip  16 . The applicator tip  16  is connected to the reservoir  10  via a transporting channel  18  and serves for applying the application fluid  12  when the pen  2  is in use. The pen is constructed in an essentially rotationally symmetrical manner about a center longitudinal axis  20 . 
     The cap  6 , in the exemplary embodiment, is configured as an outer cap  30  and contains an inner cap  32  accommodated therein. In the axial direction of the center longitudinal axis  20  of the pen  2 , the inner cap  32  is approximately a third shorter than the outer cap  30 . In  FIG. 1 , the inner cap  32  is located in the position in which it has been advanced all the way to the front end  34  of the outer cap  30 . Remaining between the base  36  of the outer cap and the base  38  of the inner cap, then, is a storage chamber  40 , in which a storage element  42  is accommodated. The storage element  42  is impregnated with a sacrificial liquid  44  from which evaporates, at room temperature, a sacrificial solvent  45 , which is distributed in the storage chamber  40 . The inner cap  32  is formed essentially by a wall portion in the form of a base  38  and by a sleeve-like wall which adjoins the wall portion and, in turn, constitutes a driver element  39  for the base  38 . 
     The storage element  42  is retained in the interior of the outer cap  30 , i.e. in the storage chamber  40 , by three—or, in an alternative embodiment, a plurality of—clamping webs  46  distributed over the circumference of the cap  6 , only two of these clamping webs being visible in  FIG. 1 . Those ends  48  of the clamping webs  46  which are oriented in the direction of the opening  24  form, at the same time, a stop for the inner cap  32  in the direction of the arrow  50  in that relative position between the inner cap  32  and outer cap  30  which is shown in  FIG. 1 . 
     The cap  32 , in a head region which acts as a sealing element  52 , has the external diameter d a  of its outside  53  dimensioned somewhat smaller than the internal diameter d i  of the outer cap  30  on its inside  51 . Along a longitudinal portion  54 , an annular gap  56  thus remains free between the outer cap  30  and inner cap  32 . The annular gap  56 , a gap  58  which adjoins the same, and a bore  60 —or, in an alternative embodiment, a plurality of bores  60 —in the inner cap  32  form a channel  72  which connects the storage chamber  40  to the cavity  22 . 
       FIG. 2  illustrates the corresponding conditions on an enlarged scale. In the open position  47  of the channel  72  shown, sacrificial solvent  45  passes out of the storage chamber  40  through the annular gap  56 . In contrast, sacrificial liquid  44  is held back on account of the small dimensioning of the inside width of the annular gap  56 . Sacrificial solvent  45  thus encloses the applicator tip  16  in the cavity  22  in order to safeguard this applicator tip against drying out. 
     In order to maintain the annular gap  56 , or in order to mount the inner cap  32  concentrically in the outer cap  30 , the latter is centered via three—or, in an alternative embodiment, a plurality of—noses  62  distributed over its circumference and via an annular seal  64  fitted on the inside  51  of the outer cap  30 . The individual noses  62 , moreover, leave space between them for forming the channel  72 . The annular seal  64  here also bounds the gap  58 , in the open position  47  shown, in the direction of the opening  24 . The cavity  22 , in turn, is sealed by an annular seal  66  which is fitted on the inside  63  of the inner cap  32  and acts on the shank portion  14 . In addition, the outer cap  30  is also sealed in relation to the shank  4  or container  8  by a further annular seal  68 . In order for the cap  6  to be fastened securely on the shank  4 , the two components are provided with a portion  70  which, in the exemplary embodiment, is configured as a screw thread. 
     In order for the pen  2  to be used, the cap  6  is released in the first instance by being unscrewed from the portion  70 . As a result, the annular seal  64  negotiates an inwardly projecting shoulder  69  of the inner cap  32 , for which reason the frictional resistance between the outer cap  30  and inner cap  32  decreases abruptly. The outer cap  30  is then pulled off further in the direction of the arrow  50 . In the first instance here, a relative movement takes place between the outer cap  30  and inner cap  32 , since the inner cap  32  is retained in the first instance on the shank portion  14 , that is to say remains initially in an unchanged position in relation to the shank  4 . This is brought about by latching noses  80  which are arranged on the outside of the shank portion  14  and engage behind a correspondingly latching protrusion  82  on the inner cap  32 .  FIG. 3  shows the corresponding detail III in this respect. 
     The outer cap  30  thus continues to move away from the inner cap  32  in the direction of the arrow  50  until the sealing element  52  leaves the longitudinal portion  54  and runs with sealing action onto a closure element  84  which is arranged on the inside  51  of the outer cap  30  and, in the exemplary embodiment, is configured as an annular seal. The corresponding situation is illustrated in  FIG. 4  and, in detail form, in  FIG. 5 . By virtue of the closure element  84 , the annular gap  56 , and thus the entire channel  72 , is closed and/or the storage chamber  40  is hermetically sealed. Solvent  44  cannot evaporate needlessly via the gap  58 , which is no longer sealed in relation to the surroundings. In the situation which is shown in  FIGS. 4 and 5 , the relative movement between the outer cap  30  and inner cap  32  terminates since the nose  62  strikes against the annular seal  64 . In addition to performing its sealing function, the annular seal  64  thus fulfills a double purpose as a stop  65 . Further pulling on the outer cap  30  in the direction of the arrow  50  causes the latching force of the latching noses  80  from the latching protrusions  82  to be overcome and thus results in them disengaging and thus in the cap  6  as a whole being released from the shank  4  or shank portion  14 . Although the force to which the outer cap  30  is exerted overcomes the latching force here, it does not overcome the higher force with which the noses  62  strike against the stop  65 .  FIGS. 4  and  5  thus show the channel  72  and the cap  6  as a whole in the sealing position  49  which has now been reached. 
       FIG. 6  shows the cap  6  in its fully released state.  FIG. 6  also clearly shows that the storage chamber  40  is closed off with sealing action by the annular seal  84 , in conjunction with the sealing element  52  of the inner cap  32 , in relation to the gap  58 , or the cavity  22  communicating with the surroundings, in order to prevent the sacrificial liquid  44  from evaporating unnecessarily. At the opening  24 , the end portion of the inner sleeve  32  forms a skirt  86 . Upon release of the cap  6 , by the relative movement between the outer sleeve  30  and inner sleeve  32 , this skirt is pushed over the inside of the portion  70  of the outer sleeve  30 . The screw thread is thus safeguarded, for example, against contact with the applicator tip  16  and thus against soiling, e.g. by the application fluid  12 . 
       FIG. 7  shows once again, in the detail VII, the nose  62  striking against the annular seal  64 . 
       FIG. 8  shows a cross section through the cap  6  and, in particular, the storage element  42  accommodated concentrically in the clamping webs  46  of the outer cap  30 . 
       FIG. 9  shows the outer cap  30  accommodated with sealing action in the closure element  84  when the inner cap  32  is pulled out of the outer cap  30  counter to the direction of the arrow  50 . 
       FIG. 10  shows the noses  62  which are distributed over the circumference of the inner cap  32  and serve for engaging behind the annular seal  64 . 
     When the cap  6  is being fitted on the shank  4 , in the first instance the shank portion  14  comes into contact with the inner cap  32  and subjects the latter to a force in the direction of the arrow  50 , for which reason a relative movement takes place in this direction between the inner cap  32  and outer cap  30 . The sealing element  52  slides off from the closure element  84  and frees the annular gap  56  and/or the channel  72 . The relative movement is continued until engagement of the thread, now freed again from the skirt  86 , in the portion  70 . By virtue of the cap  6  being screwed onto the shank  4 , finally, the inner cap  32  slides into the outer cap  30  again until its base  38  reaches the ends  48  of the clamping webs  46  and strikes against the same. Finally, the latching noses  80  then latch behind the latching protrusions  82 , and at the same time the cap  6 , with the aid of the screw thread, reaches its definitive position with sealing action, and engagement of all the seals  64 ,  66  and  68 , on the shank  4 . 
     Since the driver element  39  of the inner sleeve  32  carries both the latching noses  62 , which are used for the pulling-off operation, and the latching protrusions  82 , it causes the base  38  to move. 
       FIG. 11  shows part of an alternative cap  6 . Instead of the storage element  42 , with the aid of the clamping webs  46 , a cartridge  90  has been clamped in the storage chamber  40  at the base  36 . The cartridge  90  has a diffusion-sealed wall  94  which encloses a reservoir  92  for sacrificial liquid  44 . On the side which is directed away from the base  36 , the reservoir  92  is closed by a membrane  96 —or, as an alternative, by a sintered disk. This allows sacrificial solvent  45  to pass through, but holds the sacrificial liquid  44  back. The membrane or sintered disk is welded with sealing action, for example, to the wall  94 . During assembly of the pen  2 , the cartridge is introduced into the cap  6  in the direction of the arrow  50 . 
     In an alternative embodiment of a cap  6 , the latter does not contain any cartridge  90 . The storage chamber  40  is then filled solely with sacrificial liquid  44 . In this embodiment, the inner cap  32  is arranged in a fixed state, that is to say in a non-displaceable manner, in the outer cap  30 . This is achieved for example by a suitable clamping device (not illustrated), between the two sub-caps. The channel  72  then subjects the sacrificial liquid  44  to a capillary force and tapers in the direction of the arrow  50 . This prevents sacrificial liquid  44  from passing out of the storage chamber  40 , but ensures that it evaporates. 
       FIG. 12  shows an alternative embodiment of a cartridge  90  in which the wall  94  is integral with the inner cap  32  or the base  38  thereof. The membrane  96  in this case, in contrast to  FIG. 11 , is directed toward the base  36 . Since, as in  FIG. 11 , it is also the case in  FIG. 12  that the cartridge  90  does not completely fill the storage chamber  40 , it is once again possible for sacrificial solvent  45  to pass in a known manner through the channel  72  into the cavity  22 . 
     It is also conceivable in accordance with  FIG. 12  to have an alternative embodiment of the cap  6  in which the inner cap  32  is mounted in a fixed state, that is to say in a non-displaceable manner, in the outer cap  30 . In this case however—in contrast to the corresponding embodiment according to FIG.  11 —the two sub-caps are sealed in relation to one another in the region of the sealing element  52 . It is thus not possible for any sacrificial solvent  45  or any sacrificial liquid  44  to pass through there. There is no longer any channel  72  present there. Instead of this, the base  38  has incorporated into it a capillary channel  106  which forms the channel  72  for the diffusion of sacrificial solvent  45  and/or sacrificial liquid  44 . The latter then passes through the channel  106  into the cavity  22  directly from the storage chamber  40 . In this embodiment, the membrane  96 , which is no longer required, has been replaced by a sealing wall portion  108 . 
       FIG. 13  shows a further alternative embodiment of a cartridge  90 . In this case, the base  38  of the cap  6  is provided with a through-passage  98 , although this has been closed again by the cartridge  90 . The cartridge  90  here, during assembly of the pen  2 , is pressed into the outer cap  30  counter to the direction of the arrow  50  until it strikes with sealing action against a stop  102  by way of a protrusion  100 . 
     In an alternative embodiment, the wall  94  contains a through-passage in the region of the base  38  and a see-through window  104  is inserted here. This allows a visual check to be made in respect of the filling level of sacrificial liquid  44  in the cartridge  90 . It is also conceivable for the entire receptacle, that is to say in particular the entire wall  94 , to be transparent. 
       FIG. 14  shows a cartridge  90  in an alternative configuration to  FIG. 13 , the only difference being that the protrusion  100  and stop  102  are facing in the opposite direction, in which case, during assembly of the pen  2 , the cartridge  90  is inserted into the outer cap  30  in the direction of the arrow  50 .