Field of Invention

The invention relates to a plastic cap for a container and to an assembly comprising a container and a plastic cap.

Prior art

From the prior art, a classic cap is known which has a cylindrical wall that is provided on the inside with a thread which can engage an outer thread formed on the neck of the container. An example of such a cap is known from U.S. Pat. No. 4,402,415 A. A disadvantage of such a cap is that, in the worst case, it is necessary to fully rotate the cap on the neck of the container before the inner thread of the cap engages the outer thread on the neck of the container, and then more rotations are needed for the cap to take its closed position and this is time consuming.

US RE37 243 E discloses a container cap that is provided with a plurality of circumferentially spaced thread-shaped gaps that can engage a plurality of circumferentially spaced thread-shaped ridges on the neck of the container. In this variant, a full rotation is no longer required to bring the grooves into engagement with the ridges, and the number of turns of the cap on the neck of the container required to bring the cap into the closed position is smaller.

In recent times, the problem of plastic waste has become increasingly acute. For both ecological and economic reasons, the desire is to reduce the amount of plastic needed to make a cap. Technical problem

The technical problem is how to provide a plastic cap for a container, which will be easy to position on the neck of the container, which can be quickly moved to the closed position (with a small twist on the neck of the container) and which will require a small amount of plastic for the production.

Solution to the technical problem

The relative expressions such as above, below, vertically, etc. are defined with respect to the container, when it is vertically oriented, i.e. the bottom of the container is below and the neck of the container is above and the cap is oriented so that it can be arranged on the neck of the container.

The technical problem is solved with a plastic cap comprising: an outer cylindrical wall, a bottom closing the outer cylindrical wall at one end, an inner cylindrical wall extending from the bottom in the same direction as the outer cylindrical wall and arranged coaxially with the outer cylindrical wall, and at least two cylindrical pins, preferably at least three cylindrical pins, which are arranged on the inner side of the inner cylindrical wall proximal to its outer edge at the same height and are evenly spaced around the circumference.

The advantage of the cap according to the invention is that less plastic is needed for its production. If the cylindrical pins were arranged on the outer wall, this wall should be formed rigidly to prevent deformation of the cap when it is mounted on the container shoulder, as deformation makes it difficult to position the cap on the container shoulder. In fact, the rigidity of the wall is achieved with a greater wall thickness. In the cap according to the invention, the outer wall can be formed thin, since its deformation does not affect the positioning of the cap on the container shoulder. Material savings can be up to 30%. This means lower material consumption and thus greater economy on the one hand and less waste on the other.

Figure 1: Cap in perspective view

Figure 2: Cap in cross-section

Figure 3: Assembly of parts in cross-section

Figure 4: Container shoulder and neck in perspective view

Figure 5: Container shoulder and neck in side view

The invention is described in more detail in the following.

The technical problem is solved with a plastic cap 10 comprising: an outer cylindrical wall 11, a bottom 12 closing the outer cylindrical wall 11 at one end, an inner cylindrical wall 13 extending from the bottom 12 in the same direction as the outer cylindrical wall and arranged coaxially with the outer cylindrical wall 11, and at least two cylindrical pins 14, preferably at least three cylindrical pins, which are arranged on the inner side of the inner cylindrical wall 13 proximal to its outer edge at the same height and are evenly spaced around the circumference.

The cap according to the invention can be provided with two cylindrical pins, but this embodiment does not ensure a plane-parallel arrangement of the cap on the container shoulder. According to a preferred embodiment, the cap has at least three cylindrical pins, thus providing for a plane-parallel arrangement of the cap on the container shoulder. The cap 10 may be further provided with an annular ridge 15 arranged on the inner side of the bottom 12 of the cap coaxially with the cylindrical walls. The purpose of the ridge is to press against the upper surface of the container neck in the position when it is mounted on the container, thus ensuring a good seal of the cap.

Examples of suitable plastic materials for producing the cap are polypropylene (PP) and high-density polyethylene (PE HD).

A further subject of the invention is an assembly of parts comprising said plastic cap 10 and a container 20, in particular a tube, comprising: a container body 21 for receiving a medium, a neck 22 for dispensing the medium and a shoulder 23 connecting the container body 21 to the neck 22, wherein the shoulder portion is formed of solid portions 24 and gaps 25 evenly spaced in alternations around the circumference of the shoulder, the number of solid portions 24 or gaps 25 respectively corresponding to the number of cylindrical pins 14 of the cap, and wherein a groove 24a is made in the solid portion from the outer direction of the circumference to receive the cylindrical pin of the cap, the groove descending slightly from a lower surface 25a of the gap downwards. The inclination of surfaces 24c of the groove is 8 to 12° with respect to the horizontal, preferably about 9.5°. An end portion 24d of the groove may be formed horizontally oriented. The horizontally oriented groove section makes it easier to control the height of fit of the cap on the shoulder and the force with which the cap presses on the container neck when the cap is in the closed position.

It is sufficient for the groove to extend beyond a circumferential angle of 15 to 25° when viewed from the central axis of the container. Consequently, when closing the container with the cap, only a 15 to 25° twist of the cap is required once the cylindrical pins engage the grooves for the cap to reach its final closed position. At least one groove may be further provided with a protrusion 24b arranged in a way to fix the cylindrical pin 14 in the closed position of the cap. The protrusion keeps the cap in the closed position. At the same time, the "click" caused by the passage of the cylindrical pin 14 past the protrusion 24b when closing the container with the cap is an indication to the user that the cap is in the final, i.e. closed position.

Circumferential vertical surfaces 25c of the gaps may be provided at the upper end with a first chamfer or with a first rounding 25b. The purpose of the first chamfer or the first rounding is to make it easier to centre the cap on the container shoulder.

Also, upper surfaces 24e of the solid parts at the end facing the grooves are provided with a second chamfer or with a second rounding 24f. The purpose of this second chamfer or second rounding is to make the cap slide into the depth more smoothly when the cylindrical pins first abut the upper surfaces of the solid parts when closing the container and only slide into the gap after the cap has been twisted.